研究者情報

マスター

アカウント（マスター）

• 氏名

  青木　芳尚(アオキ　ヨシタカ), アオキ　ヨシタカ

所属（マスター）

• 工学研究院　応用化学部門　機能材料化学分野

所属（マスター）

• 工学研究院　応用化学部門　機能材料化学分野

独自項目

syllabus

• 2021, 応用物質化学（電子材料化学特論）, Applied Materials Chemistry (Physical Chemistry of Electronic Materials), 修士課程, 総合化学院, エネルギーデバイス，半導体，イオン伝導体，ヘテロ界面，欠陥熱力学
• 2021, 物理化学Ⅰ, Physical Chemistry Ⅰ, 学士課程, 工学部, 熱力学，気体の運動，物質の状態，エネルギー，自発反応，熱力学関数，平衡
• 2021, 物理化学演習, Exercise on Physical Chemistry, 学士課程, 工学部, 平衡計算，数値計算，作図
• 2021, 応用化学学生実験Ⅰ, Applied Chemistry Laboratory Ⅰ, 学士課程, 工学部, 実験技術、安全、酸化還元滴定、キレート滴定、酸塩基平衡、錯形成平衡、吸光光度法、クラジウス－クラペイロンの式、蒸発エンタルピー、電荷移動錯体、分子間相互作用、電極反応、計測制御、吸収・蛍光スペクトル、分子軌道論、反応速度、アレニウスの式
• 2021, 英語演習, English Seminar, 学士課程, 全学教育, 英語，化学，工学
• 2021, 物質変換工学, Applied Chemistry and Biochemistry, 学士課程, 工学部, 有機合成，有機材料，化学プロセス，反応器設計，生体材料，高分子材料，分子機能，無機材料，複合材料，電子材料，光機能材料

researchmap

プロフィール情報

学位

• 博士（工学）（北海道大学）

プロフィール情報

• 姓

  青木, Aoki

• 名

  芳尚, Yoshitaka

• ID各種

  201301019491039772

対象リソース

http://labs.eng.hokudai.ac.jp/labo/elechem/

業績リスト

研究キーワード

• Ammonia electrolysis synthesis by protonic solid oxide cells   Protonic solid oxide fuel cells   Protonic solid oxide electrolysis cells   電気化学   固体イオニクス   

研究分野

• ナノテク・材料 / 無機材料、物性 / イオン伝導体
• ナノテク・材料 / エネルギー化学 / 固体イオニクス

経歴

• 2010年06月 - 現在 北海道大学 准教授
• 2013年10月 - 2017年03月 JST さきがけ「再生可能エネルギーからのエネルギーキャリアの製造とその利用のための革新的基盤技術の創出」 さきがけ研究員
• 2011年01月 - 2012年06月 RWTH-Aachen 博士研究員
• 2008年07月 - 2010年05月 北海道大学 助教
• 2002年04月 - 2008年07月 理化学研究所 博士研究員
• 2003年07月 - 2005年06月 Massacusetts University 博士研究員

学歴

• 1997年04月 - 2002年03月   北海道大学大学院
• 1993年04月 - 1997年03月   北海道大学

委員歴

• 2023年04月 - 現在   SOFC研究会   常任幹事
• 2011年07月 - 現在   電気化学会北海道支部   常任幹事
• 2018年04月 - 2023年03月   文部科学省 科学技術予測センター   NISTEP専門調査員
• 2015年04月 - 2018年03月   北海道大学工学部国際連携委員
• 2014年04月 - 2016年03月   北海道大学安全衛生委員
• 2014年04月 - 2016年03月   日本電気化学会   編集委員
• 2015年04月 - 2015年12月   第41回固体イオニクス討論会実行委委員
• 2015年04月 - 2015年06月   第31回ライラックセミナー・第21回若手研究者交流会・産官学フォーラム講演会合同大会
• 2014年04月 - 2014年09月   2014年電気化学秋季大会実行委員

受賞

• 2021年03月 日本電気化学会 学術賞
   プロトン固体酸化物セルの体系的研究 

  受賞者: 青木芳尚
• 2009年01月 日本化学会北海道支部奨励賞
  

論文

• Systematic combination of palladium facets and monolayer metal hydroxide nanosheets for promotion of ethanol oxidation reaction

  Sho Kitano, Hiroya Motohashi, Mana Iwai, Koji Fushimi, Yoshitaka Aoki, Hiroki Habazaki

  Applied Surface Science 2024年10月
• Preparation of highly active and durable electrodes for alkaline water electrolysis by anodizing of commercial FeNi and FeNiCo alloys

  Xiong Zetao, David Quintero, Sho Kitano, Tomoya Nagao, Mana Iwai, Yoshitaka Aoki, Koji Fushimi, Hiroki Habazaki

  Electrochimica Acta 491 2024年07月01日 

  Anodizing is gaining popularity as a binder-free fabrication route for obtaining catalyst materials directly on the current collector without using noble metals, binders, or conductive carbon additives. Here, we fabricate promising highly active electrodes for alkaline water electrolysis by anodizing commercial FeNi and FeNiCo alloys (%wt. Fe range between 22 and 63) in an ethylene glycol-based fluoride electrolyte. Anodizing forms metal fluoride coatings, which are converted to OER active compounds (γ-NiOOH:Fe) during potential cycling in an alkaline aqueous solution (1 mol L−1 (M) KOH at 293 K) as a result of leaching of fluoride ions. The morphology, thickness, and number of active sites are influenced by the amount of Fe in the alloy, and the electrode with the highest electrochemical active surface area (Kovar alloy with a 54 %wt. Fe) shows the largest OER activity enhancement by anodizing. The performance evaluation in practical conditions (7 mol L−1 KOH at 343 K) demonstrated a highly active performance with an OER potential as low as 1.52 V at a current density of 600 mA cm−2 even for electrodes obtained in alloys with a low amount of Fe (78-Permalloy with a 22 %wt. Fe), demonstrating that anodizing is an effective way to develop highly active OER electrodes from commercially available alloys. On the other hand, anodizing is a good fluoridation route for transition metals with good results in the formation of F-enriched precursors that efficiently promote active phase formation during the catalytic process, offering the possibility of obtaining catalysts directly on the current collector in a one-step process, easily implemented in industrial applications.
• Unveiling the Origin of Fast Hydride Ion Diffusion at Grain Boundaries in Nanocrystalline TiN Membranes

  Yuji Kunisada, Chiharu Kura, Norihito Sakaguchi, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  ACS Omega 2024年03月26日
• Vanadium Nitride Is an Efficient Hydrogen-Diffusive Cathode for Green Ammonia Electrochemical Synthesis by Protonic Solid Oxide Electrolysis Cells

  Naoki Kamitani, SeongWoo Jeong, Hiroki Habazaki, Yoshitaka Aoki

  ACS Sustainable Chemistry & Engineering 2024年02月05日
• Boosting high-performance in Zr-rich side protonic solid oxide electrolysis cells by optimizing functional interlayer

  Chunmei Tang, Ning Wang, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki, Siyu Ye

  Green Energy and Environment 2024年 

  Protonic solid oxide electrolysis cells (P-SOECs) are a promising technology for water electrolysis to produce green hydrogen. However, there are still challenges related key materials and anode/electrolyte interface. P-SOECs with Zr-rich electrolyte, called Zr-rich side P-SOECs, possess high thermodynamically stability under high steam concentrations but the large reaction resistances and the current leakage, thus the inferior performances. In this study, an efficient functional interlayer Ba0.95La0.05Fe0.8Zn0.2O3−δ (BLFZ) in-between the anode and the electrolyte is developed. The electrochemical performances of P-SOECs are greatly enhanced because the BLFZ can greatly increase the interface contact, boost anode reaction kinetics, and increase proton injection into electrolyte. As a result, the P-SOEC yields high current density of 0.83 A cm−2 at 600 °C in 1.3 V among all the reported Zr-rich side cells. This work not only offers an efficient functional interlayer for P-SOECs but also holds the potential to achieve P-SOECs with high performances and long-term stability.
• Green hydrogen production by intermediate‐temperature protonic solid oxide electrolysis cells: Advances, challenges, and perspectives

  Chunmei Tang, Yao Yao, Ning Wang, Xiaohan Zhang, Fangyuan Zheng, Lei Du, Dongxiang Luo, Yoshitaka Aoki, Siyu Ye

  InfoMat 2023年12月20日 [査読有り][通常論文]
   

  Abstract Protonic solid oxide electrolysis cells (P‐SOECs) operating at intermediate temperatures, which have low costs, low environmental impact, and high theoretical electrolysis efficiency, are considered promising next‐generation energy conversion devices for green hydrogen production. However, the developments and applications of P‐SOECs are restricted by numerous material‐ and interface‐related issues, including carrier mismatch between the anode and electrolyte, current leakage in the electrolyte, poor interfacial contact, and chemical stability. Over the past few decades, considerable attempts have been made to address these issues by improving the properties of P‐SOECs. This review comprehensively explores the recent advances in the mechanisms governing steam electrolysis in P‐SOECs, optimization strategies, specially designed components, electrochemical performance, and durability. In particular, given that the lack of suitable anode materials has significantly impeded P‐SOEC development, the relationships between the transferred carriers and the cell performance, reaction models, and surface decoration approaches are meticulously probed. Finally, the challenges hindering P‐SOEC development are discussed and recommendations for future research directions, including theoretical calculations and simulations, structural modification approaches, and large‐scale single‐cell fabrication, are proposed to stimulate research on P‐SOECs and thereby realize efficient electricity‐to‐hydrogen conversion.image
• Lithiation of Anodic Magnetite–Hematite Nanotubes Formed on Iron

  Laras Fadillah, Damian Kowalski, Mewin Vincent, Chunyu Zhu, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki

  ACS Applied Materials & Interfaces 2023年11月06日
• Biomass derived porous carbon for superior electrocatalysts for oxygen reduction reaction

  Chunyu Zhu, Bo Zhao, Manami Takata, Yoshitaka Aoki, Hiroki Habazaki

  Journal of Applied Electrochemistry 53 7 1379 - 1388 2023年07月 

  The preparation of porous carbon from biomass flour as high-performance electrocatalysts for oxygen reduction reaction (ORR) was reported in this paper. The fast and vigorous pyrolysis of flour was induced in the presence of magnesium nitrate, by which MgO nanoparticles were introduced as nano-template to create numerous nanopores and to increase the specific surface area (SSA). The pore structure, SSA and elemental dopant were influenced by the ratio of biomass to magnesium nitrate and calcination temperature. A highly hierarchical micro-meso-macroporous carbon, which was calcined at 1000 °C and had a high SSA of 1880 m2 g−1, exhibited the best ORR performance in terms of fast ORR kinetic, superior stability and excellent methanol tolerance. Graphical Abstract: [Figure not available: see fulltext.]
• Highly enhanced photocatalytic activity of nanotubular Fe2O3/Fe2WO6 nanocomposite film formed by anodizing FeW alloy

  Laras Fadillah, Damian Kowalski, Sho Kitano, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  Electrochemistry Communications 149 2023年04月 

  This study demonstrates the highly enhanced photocatalytic activity of Fe2O3 nanotubes by making a heterojunction with Fe2WO6 and doping of W6+ ions into the α-Fe2O3 phase for water splitting and decomposition of an organic pollutant. Both nanotubular and compact Fe2O3/Fe2WO6 films are formed by anodizing the magnetron-sputtered Fe-9 at% W alloy in fluoride-containing ethylene glycol electrolyte and subsequent annealing at 450 °C. Their photocatalytic activities are compared with W-free nanoporous Fe2O3 film formed on high-purity Fe. The nanotubular Fe2O3/Fe2WO6 film exhibits a markedly enhanced photoelectrochemical oxygen evolution reaction and photocatalytic degradation of methylene blue compared with the nanoporous W-free Fe2O3 film. Because of the larger surface area, the nanotubular Fe2O3/Fe2WO6 film reveals further increased activity than the compact Fe2O3/Fe2WO6 film. The STEM study discloses the dispersion of Fe2WO6 nanoparticles in the α-Fe2O3 phase after annealing at 450 °C, and XRD analysis shows the possible doping of W species into α-Fe2O3. The formation of the W-doped α-Fe2O3/Fe2WO6 heterojunction likely promotes the separation of photogenerated electron-hole pairs, enhancing photocatalytic activity. Hence, the nanotubular Fe2O3/Fe2WO6 film is a possible candidate for visible-light-driven photocatalysts.
• Studies on Protonic Solid Oxide Cells

  Yoshitaka AOKI

  Electrochemistry 2023年
• Sustainable high-energy aqueous zinc-manganese dioxide batteries enabled by stress-governed metal electrodeposition and fast zinc diffusivity

  Huijun Yang, Ruijie Zhu, Yang Yang, Ziyang Lu, Zhi Chang, Ping He, Chunyu Zhu, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki, Haoshen Zhou

  Energy and Environmental Science 2023年 

  The re-evaluation of zinc (Zn)-based energy storage systems satisfies emerging demands in terms of safety and cost-effectiveness. However, the dendritic Zn morphology and resulting short circuits within the cell remain long-standing challenges. Moreover, diverse Zn dendrite propagation exacerbates the situation, particularly during high-capacity battery operation. The high-capacity Zn deposition/dissolution process involves numerous sites and interfaces, which leads to disordered Zn dendrite growth because of the inherent diffusion-limited aggregation mechanism. Here, we demonstrate a robust polymer separator that serves as both a physical barrier to stress-governed metal electrodeposition and an ionic charge carrier for fast Zn2+ diffusivity. These insights enable an ultra-high Zn reversibility (99.97%) for 2000 cycles at 20.0 mA cm−2 and 4.0 mA h cm−2, and a high-energy-density (115 W h kg−1 based on pouch cell) Zn-MnO2 full battery with an aggressive N/P capacity ratio (1.35). The abundant and environmentally friendly cell components make it a sustainable battery technology for global electrification.
• Facile synthesis approach of bifunctional Co–Ni–Fe oxyhydroxide and spinel oxide composite electrocatalysts from hydroxide and layered double hydroxide composite precursors

  Sho Kitano, Yuki Sato, Reiko Tagusari, Ruijie Zhu, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  RSC Advances 13 16 10681 - 10692 2023年 

  Simple and durable: the multi-metal oxyhydroxide and spinal oxide composite catalyst containing Co, Fe and Ni are synthesized from hydroxide and layered double hydroxide composite precursors and shows excellent bifunctional ORR/OER activities.
• Machine-Learning-Accelerated Development of Efficient Mixed Protonic–Electronic Conducting Oxides as the Air Electrodes for Protonic Ceramic Cells

  Ning Wang, Baoyin Yuan, Chunmei Tang, Lei Du, Ruijie Zhu, Yoshitaka Aoki, Weibo Wang, Lixin Xing, Siyu Ye

  Advanced Materials 34 51 2022年12月22日 

  Currently, the development of high-performance protonic ceramic cells (PCCs) is limited by the scarcity of efficient mixed protonic–electronic conducting oxides that can act as air electrodes to satisfy the high protonic conductivity of electrolytes. Despite the extensive research efforts in the past decades, the development of mixed protonic–electronic conducting oxides still remains in a trial-and-error process, which is extremely time consuming and high cost. Herein, based on the data acquired from the published literature, the machine-learning (ML) method is introduced to accelerate the discovery of efficient mixed protonic–electronic conducting oxides. Accordingly, the hydrated proton concentration (HPC) of 3200 oxides is predicted to evaluate the proton conduction that is essential for enhancing the electrochemical performances of PCCs. Subsequently, feature importance for HPC is evaluated to establish a guideline for rapid and accurate design and development of high-efficiency mixed protonic–electronic conducting oxides. Thereafter, screened (La0.7Ca0.3)(Co0.8Ni0.2)O3 (LCCN7382) is prepared, and the experimental HPC adequately corresponds with the predicted results. Moreover, the PCC with LCCN7382 exhibits satisfactory electrochemical performances in electrolysis and fuel cell modes. In addition to the development of a promising air electrode for PCC, this study establishes a new avenue for ML-based development of mixed protonic–electronic conducting oxides.
• Advanced Cathode Materials for Protonic Ceramic Fuel Cells: Recent Progress and Future Perspectives

  Ning Wang, Chunmei Tang, Lei Du, Ruijie Zhu, Lixin Xing, Zhongqian Song, Baoyin Yuan, Lei Zhao, Yoshitaka Aoki, Siyu Ye

  Advanced Energy Materials 12 34 2022年09月08日 [査読有り][通常論文]
   

  Intermediate-temperature proton ceramic fuel cells (PCFCs)–a promising power generation technology–have attracted significant attention in recent years because of their unique advantages over conventional high-temperature solid oxide fuel cells and low-temperature proton exchange membrane fuel cells. The cathodes of PCFCs simultaneously require efficient channels for proton, oxide-ion, and electron transfer; therefore, designing and engineering cathode materials with tailorable H+, O2−, and e− conductivities are crucial for improving PCFC performance. Despite significant efforts and critical progress in this field, exploring the desired cathode materials remains challenging. This review provides a comprehensive and critical overview of oxide materials for PCFC cathodes, particularly triple H+/O2−/e− conductors. Their proton uptake, conduction mechanisms, and structure–property relationships are focused on to guide future material design. In addition, the electrochemical performance of these cathode materials in PCFCs is discussed and the electrochemical performance gaps among PCFCs with different types of cathode materials are defined. Finally, perspectives on the development of high-performance PCFCs are proposed.
• Functionality of the Cathode-Electrolyte Interlayer in Protonic Solid Oxide Fuel Cells

  Katsuya Akimoto, Ning Wang, Chunmei Tang, Kai Shuto, SeongWoo Jeong, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  ACS APPLIED ENERGY MATERIALS 2022年09月 

  Efficient power generation with protonic solid oxide fuel cells (H-SOFCs) remains challenging because the mismatch between the primary ion carriers of the electrolyte and the cathode limits the effective cathode reaction area to the gas-electrolyte-cathode triple-phase boundary (TPB), resulting in large cathodic overpotentials at low operating temperatures. Herein, we report the role of functional layers between an electrolyte and a cathode in reducing the cathodic reaction resistance at the TPB. Thin-film fuel cells with BaZr0.1Ce0.7Y0.1Yb0.1O3-delta (BZCYYb1711) electrolytes were fabricated using a dense La0.5Sr0.5Co0O3-delta (LSC) nanofilm (approximately 100 nm) as a cathode functional layer (CFL) with the typical oxide ion/electron mixed conductor La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF), LSC, and the less-active Sb0.1Sn0.9O2 (ATO). The peak power densities of the cells increased by >100% when using a CFL, and cells having an LSC cathode and CFL achieved power densities of 500 mW cm(-2) at 500 degrees C. The distribution of relaxation times in the impedance spectra revealed the CFL's effect on the ohmic and polarization resistances. Crucially, cells without a CFL had large ohmic resistances because the proton-accessible electrode areas were confined to the gas-cathode-electrolyte TPB. However, the resistance decreased with the CFL because coupled partial proton conductivity and electrocatalytic activity of the LSC nanofilms increased the proton-accessible electrode area. The cells without a CFL showed a large polarization resistance because of the sluggish diffusion of O adatoms over the cathode resulting from the increased TPB length. This resistance decreased by >70% with an LSC CFL because the cells did not require long-range O diffusion because of the significantly extended proton-accessible reaction area near the gas-CFL-cathode TPB. Thus, using interfacial layers is an alternative way to design new cathode materials having low cathodic polarization for H-SOFCs.
• The effect of anodizing temperature on the oxygen evolution reaction activity of anodized FeNiCo alloy in alkaline electrolyte

  Masahiro Nishimoto, Zetao Xiong, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki

  ELECTROCHIMICA ACTA 427 2022年09月 

  This study investigates the oxygen evolution reaction (OER) activity of the FeNiCo alloy anodized at several temperatures in a fluoride-containing ethylene glycol electrolyte. When the alloy is anodized at 10 V, the OER activity in KOH electrolyte is highly enhanced on the alloy anodized at 15 and 20 degrees C, at which non-uniform film growth proceeds. The fraction of the locally thick film regions increases with anodizing time, enhancing the OER activity. Only thin porous films are formed at >= 30 degrees C even though the anodizing current is high because of the promotion of film dissolution at high electrolyte temperatures. Because of the thickness limitation, the OER activity is relatively low when the anodic films are formed at >= 30 degrees C. A good correlation is found between the OER activity and the electric double-layer capacitance; thicker porous anodic films enhance the OER activity. The anodic film formed at each temperature consists of a rutile-type (FeNiCo)F-2 phase, but in KOH electrolyte, it is converted readily to an oxyhydroxide phase, which is OER active. A similar to 2 mu m-thick film obtained under the optimum anodizing condition reduces the overpotential of OER to 245 mV at 10 mA cm(-2) in 1.0 mol dm(-3) KOH electrolyte.
• Raman and glow discharge optical emission spectroscopy studies on structure and anion incorporation properties of a hydrated alumina film on aluminum

  Tatsuyuki Takano, Hisato Matsuya, Damian Kowalski, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki

  Applied Surface Science 592 2022年08月01日 

  Hydration treatment of aluminum in hot water is important for its corrosion protection, and also this treatment is a crucial pretreatment in forming dielectric crystalline alumina films on the aluminum anode in aluminum electrolytic capacitors. In this study, a two-layer hydrated film formed on high purity aluminum by hot water treatment was examined using a combination of glow discharge (GD) sputtering and Raman spectroscopy. In addition, the anion penetration behavior through the hydrated alumina layer during anodizing aluminum in several electrolytes was investigated. The results indicate that the outer layer, with a nanosheet-like morphology, consists of a crystalline pseudo-boehmite phase, whereas the relatively compact inner layer is amorphous or poorly crystalline. The inner amorphous layer plays a crucial role in the incorporation of the anions, which is found for the first time. When hydrated aluminum is anodized in phosphate, silicate, and tungstate electrolytes, the inner hydrated alumina layer impedes the penetration of these electrolyte anion species. In contrast, boron species readily penetrate the hydrated alumina layer into the barrier layer formed by anodization in boric acid. This anion-specific incorporation behavior is discussed in terms of ion-selective permeation in the amorphous hydrated alumina layer.
• Barium Indate-Zirconate Perovskite Oxyhydride with Enhanced Hydride Ion/Electron Mixed Conductivity

  Hajime Toriumi, Genki Kobayashi, Takashi Saito, Takashi Kamiyama, Takaaki Sakai, Takahiro Nomura, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  CHEMISTRY OF MATERIALS 34 16 7389 - 7401 2022年08月 

  Oxyhydrides have excellent potential as electrochemical and catalytic materials owing to the synergistic effects of the conductivity and redox activity of the hydride (H-) ion. However, harsh preparation conditions and their pyrolytic nature limit their applications. Herein, we discover highly durable oxyhydride perovskite BaZr0.5In(II)(0.5)O2.25H0.5 with enhanced H- ion-electron mixed conductivity. BaZr0.5In-(III)O-2.75, as the parent phase, was reductively hydrogenated to BaZr(0.5I)n(II)(0.5)O2.25H0.5 as via simple H-2 gas annealing at 800 degrees C under an ambient pressure with the incorporation of H- ions with simultaneous oxygen vacancy formation. Membrane devices comprising dense BaZr0.5In0.5O2.25H0.5 films on porous Ni-cermet supports were fabricated by conventional sintering and postreduction because low lattice contraction (-0.07%) following hydrogenation allowed for the bulk hydrogenation of BaZr0.5In0.5O2.75 sinters without structural collapse. The resulting devices exhibited higher hydrogen permeability than protonic ceramic ones at 500 degrees C because BaZr0.5In(II)(0.5)O2.25H0.5, allows H- ion hopping between the nearest-neighbor anion sites due to the significantly high oxygen deficiency (25% of O sites are vacant), giving rise to a H- ion conductivity of 10(-3) S cm(-1). Given their superior H- ion conductivity and ease of manufacturing, the synthesized materials have great potential for applications in mixed conducting electrodes and hydrogen-permeable membrane supports of ceramic electrochemical cells.
• Design of anode functional layers for protonic solid oxide electrolysis cells

  Chunmei Tang, Ning Wang, Ruijie Zhu, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  Journal of Materials Chemistry A 10 29 15719 - 15730 2022年07月04日 

  Protonic solid oxide electrolysis cells (P-SOECs) are one of the most efficient devices for hydrogen production from renewable electricity, but the lack of suitable anodes has led to serious concerns in terms of high anodic overpotentials and low conversion efficiencies. Herein, we demonstrated that both the steam electrolysis performances and efficiency of P-SOECs based on a BaZr0.6Ce0.2Y0.1Yb0.1O3−δ electrolyte can be significantly improved by employing a Ba0.95La0.05Fe0.8Zn0.2O3−δ (BLFZ) H+/O2−/e− triple-conductor thin film at the anode/electrolyte interface as an anode functional layer (AFL). A broad survey of electrolysis performances was conducted for cells with various AFLs, including H+/O2−/e− triple conductors and O2−/e− double conductors. This investigation clarified that BLFZ can significantly decrease the ohmic and polarization resistances, and thus, greatly increase the electrolysis current. Because of the high proton conductivity and excellent electrochemical kinetics, the BLFZ AFL can allow the anodic reactions to occur over the surfaces of the BLFZ AFL without the long-range diffusion of oxygen species over the anode. Moreover, the BLFZ AFL can depress the hole injection in the electrolyte because the water partial pressure remained relatively high in comparison to the oxygen partial pressure at the AFL/electrolyte interface due to the excellent proton conductivity. Hence, the BLFZ cell offered a high electrolysis current of 570 mA cm−2 at 1.3 V, and an increased efficiency of 75% from 46% for a cell without the BLFZ AFL at 500 °C. These results reveal that an effective AFL can boost the anodic reaction and optimize the efficiency of obtaining P-SOECs with excellent performances and outstanding ability for hydrogen production. Transition metal oxides combining high proton and low oxide ion conductivities could be promising AFLs for highly efficient P-SOECs.
• A low-cost and non-corrosive electropolishing strategy for long-life zinc metal anode in rechargeable aqueous battery

  Ruijie Zhu, Zetao Xiong, Huijun Yang, Tianhong Huang, Seongwoo Jeong, Damian Kowalski, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki, Chunyu Zhu

  Energy Storage Materials 46 223 - 232 2022年04月
• Enhanced Performance of Protonic Solid Oxide Steam Electrolysis Cell of Zr-Rich Side BaZr_0.6Ce_0.2Y_0.2O_3−δ Electrolyte with an Anode Functional Layer

  Hajime Toriumi, SeongWoo Jeong, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  ACS Omega 2022年03月09日
• Development of Hydrogen-Permeable Metal Support Electrolysis Cells

  Yoshitaka Aoki, Shinichi Nishimura, SeongWoo Jeong, Sho Kitano, Hiroki Habazaki

  ACS Applied Energy Materials 2022年01月18日
• Anode/Cathode Dual-Purpose Aluminum Current Collectors for Aqueous Zinc-Ion Batteries

  Zhu, R., Xiong, Z., Yang, H., Wang, N., Kitano, S., Zhu, C., Aoki, Y., Habazaki, H.

  Advanced Functional Materials 33 8 2022年 

  Rechargeable aqueous zinc (Zn)-ion batteries (RAZIBs), which use non-flammable aqueous electrolytes and low-cost electrode materials, show great potential to boost the development of safe, cost-effective, and highly efficient energy storage systems. The adoption of lightweight and inexpensive aluminum (Al) as current collectors seems to be a good vision, but Al exhibits an easily-corroded nature and a high impedance in aqueous electrolytes, making it a challenge to realize the utilization of Al current collector in RAZIBs. In this study, through the direct current magnetron sputtering, niobium (Nb) coated Al (Al-Nb) foils are prepared, which shows superior corrosion-resistance in an aqueous solution, while maintaining a satisfying electronic conductivity. Moreover, the Al-Nb foils can be adopted to both anode and cathode current collectors while exhibiting high coulombic efficiency and good cycling stability even when they are tested under a condition that can meet the real-world application demands, e.g., the Zn||Al-Nb half-cell shows an average coulombic efficiency of 99.17% in 320 cycles under a current density of 25 mA cm−2 and a galvanizing capacity of 6.25 mAh cm−2. The superior performance of the modified Al current collectors may mark a significant step toward the development of high-energy-density aqueous batteries.
• High-corrosion-resistance mechanism of graphitized platelet-type carbon nanofibers in the OER in a concentrated alkaline electrolyte

  Yuki Sato, Naohito Yamada, Sho Kitano, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  Journal of Materials Chemistry A 10 15 8208 - 8217 2022年 

  This study revealed excellent corrosion resistance of the highly graphitized platelet-type carbon nanofibers due to hydroxyl passivation of the carbon edge plane.
• High strength hydrogels enable dendrite-free Zn metal anodes and high-capacity Zn–MnO2 batteries via a modified mechanical suppression effect

  Ruijie Zhu, Huijun Yang, Wei Cui, Laras Fadillah, Tianhong Huang, Zetao Xiong, Chunmei Tang, Damian Kowalski, Sho Kitano, Chunyu Zhu, Daniel R. King, Takayuki Kurokawa, Yoshitaka Aoki, Hiroki Habazaki

  Journal of Materials Chemistry A 10 6 3122 - 3133 2022年 

  Although shear modulus of gel electrolytes is generally far less than that of Zn metal, a modified mechanical suppression effect of hydrogel on the growth of Zn dendrites still can be confirmed, and a Zn–MnO₂ cell with high capacity is achieved.
• Catalytic activity of graphene-covered non-noble metals governed by proton penetration in electrochemical hydrogen evolution reaction

  Kailong Hu, Tatsuhiko Ohto, Yuki Nagata, Mitsuru Wakisaka, Yoshitaka Aoki, Jun-ichi Fujita, Yoshikazu Ito

  Nature Communications 12 1 2021年12月 

  Graphene-covering is a promising approach for achieving an acid-stable, non-noble-metal-catalysed hydrogen evolution reaction (HER). Optimization of the number of graphene-covering layers and the density of defects generated by chemical doping is crucial for achieving a balance between corrosion resistance and catalytic activity. Here, we investigate the influence of charge transfer and proton penetration through the graphene layers on the HER mechanisms of the non-noble metals Ni and Cu in an acidic electrolyte. We find that increasing the number of graphene-covering layers significantly alters the HER performances of Ni and Cu. The proton penetration explored through electrochemical experiments and simulations reveals that the HER activity of the graphene-covered catalysts is governed by the degree of proton penetration, as determined by the number of graphene-covering layers.
• Highly Active and Durable FeNiCo Oxyhydroxide Oxygen Evolution Reaction Electrocatalysts Derived from Fluoride Precursors

  Masahiro Nishimoto, Sho Kitano, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  ACS Sustainable Chemistry & Engineering 9 28 9465 - 9473 2021年07月19日 

  Developing highly active and durable electrocatalysts, consisting of earth-abundant elements, for oxygen evolution reaction (OER) is pivotal for large-scale water splitting for hydrogen production. Herein, we report that the commercially available FeNiCo alloy can be converted to a highly active electrocatalyst for OER by galvanostatic anodizing in a fluoride-containing ethylene glycol electrolyte. Anodizing of the alloy develops a porous film consisting of the (FeNiCo)F2 phase, which is readily converted to a highly active porous oxyhydroxide during anodic polarization in a KOH electrolyte. The anodized alloy exhibits high activity and high durability for OER with an overpotential as low as 0.26 V at a current density of 10 mA cm-2. The present study demonstrates that a simple and cost-effective anodizing process can be used to form a highly active OER electrode from a low-cost, practical, iron-based alloy. In addition, we found that fluorides containing Fe, Ni, and Co are excellent precursors for the formation of oxyhydroxides exhibiting high OER activity and durability.
• In Situ Activation of a Manganese Perovskite Oxygen Reduction Catalyst in Concentrated Alkaline Media

  Yoshitaka Aoki, Kentaro Takase, Hisao Kiuchi, Damian Kowalski, Yuki Sato, Hajime Toriumi, Sho Kitano, Hiroki Habazaki

  Journal of the American Chemical Society 143 17 6505 - 6515 2021年05月05日 [査読有り][通常論文]
  
• La0.8Sr0.2Co1-xNixO3-δ as the Efficient Triple Conductor Air Electrode for Protonic Ceramic Cells

  Ning Wang, Hajime Toriumi, Yuki Sato, Chunmei Tang, Takashi Nakamura, Koji Amezawa, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  ACS Applied Energy Materials 4 1 554 - 563 2021年01月25日 [査読有り]
   

  Highly efficient mixed H+/e(-)/O2- triple conducting air electrodes are indispensable for improving the electrochemical performance of protonic ceramic fuel cells and electrolysis cells (PCFC/ECs) operating at intermediate temperatures. This study demonstrates that single perovskite-type La0.8Sr0.2Co1-xNixO3-delta families (LSCN, x = 0-0.3) are efficient H+/e(-)/O2- triple conductors due to a pronounced hydration ability at elevated temperatures with a related enthalpy of -107 kJ mol(-1). Thermogravimetry confirmed that the oxides were capable of a 0.01 mole fraction proton uptake at 600 degrees C and p(H2O) of 0.023 atm. Reversible protonic ceramic cells were fabricated using these oxides as an air electrode and exhibited promising performance with a peak power density of 0.88 W cm(-2) in fuel cell mode and an electrolysis current of 1.09 A cm(-2) at a thermal neutral voltage in electrolysis cell mode at 600 degrees C. Impedance analysis confirmed that the polarization resistance of the La0.8Sr0.2Co0.2Ni0.3O3-delta cell was 0.09 Omega cm(2) under an open circuit potential at 600 degrees C, which is much smaller than the polarization resistances reported for cells with a single or double perovskite-type triple conductor. The current results indicate that mixed H+/e(-)/O2- triple phase conducting LSCN oxides are promising air electrodes for protonic ceramic cells operating in the intermediate temperature region at approximately 600 degrees C.
• Metal/Oxide Heterojunction Boosts Fuel Cell Cathode Reaction at Low Temperatures

  Seong Woo Jeong, Ning Wang, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  Advanced Energy Materials 2021年 

  Among several types of low-temperature solid oxide fuel cells, hydrogen-permeable metal-supported fuel cells (HMFCs) are devices that can achieve outputs of approximately 1.0 W cm−2 at 400 °C. This work clarifies the mechanism for promoting the cathode reaction on proton-conducting ceramics at such low temperatures. Combined numerical and electrochemical analyses demonstrate that blocking minor oxide ion conduction at metal/oxide heterojunctions promotes proton transfer at the cathode/electrolyte interfaces, thereby enhancing the turnover frequency of the cathode reaction at the triple-phase boundary. The electrolyte membrane in HMFCs is forced to gain extra protons to compensate for the charge of oxide ions that accumulate because of the blocking, resulting in an increment of the proton concentration gradients near the cathode/electrolyte interfaces so as to eject the excess amount of proton. The interfacial proton concentration gradient increases and thus the cathode polarization resistance of HMFCs decrease with the cell bias. An HMFC with a highly oxygen-deficient BaZr0.5Sc0.5O3−δ electrolyte accumulates a large amount of oxide ions, thereby developing large concentration gradients. Thus, it achieves a cathode reaction resistance of 0.54 Ω cm2 at 400 °C with conventional cathode materials, La0.6Sr0.4Co0.2Fe0.8O3−δ. These findings demonstrate that HMFCs can efficiently utilize overpotential.
• Formation of Mobile Hydridic Defects in Zirconium Nitride Films with n-Type Semiconductor Properties

  Miku Saito, Chiharu Kura, Hajime Toriumi, Satoshi Hinokuma, Toshiaki Ina, Hiroki Habazaki, Yoshitaka Aoki

  ACS Applied Electronic Materials 2021年 

  The incorporation of mobile hydridic defects was demonstrated for low-crystalline zirconium nitride (Zr3N4-?) films deposited by radio frequency reactive sputtering under a flow of nitrogen-rich reactive gases. Extended X-ray adsorption fine structure analysis confirmed that the local coordination environment around the Zr atoms was very close to that of the orthorhombic Eu3O4 phase. Pristine Zr3N4-? films exhibited n-type semiconductor behavior due to the presence of nitrogen vacancy donors with a carrier concentration of 1.4 × 1020 cm-3 and an electron mobility of 2.2 × 10-3 cm2 V-1 s-1 at room temperature. Electrochemical and spectroscopic measurements confirmed that Zr3N4-? was readily hydrogenated upon exposure to H2 gas at 300 °C to form hydridic defects via electron donation to hydrogen adatoms. Hence, the hydrogenated film exhibited H- ion/electron mixed conductor behavior in a H2 atmosphere. These findings open the possibility for exploring new hydride ion conductors based on thermodynamically stable transition metal nitrides.
• Slippery Liquid-Infused Porous Surfaces on Aluminum for Corrosion Protection with Improved Self-Healing Ability

  Kensuke Sakuraba, Sho Kitano, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  ACS Applied Materials and Interfaces 2021年 

  Slippery liquid-infused porous surfaces (SLIPSs) can be formed by impregnating lubricants in porous surfaces with low surface energy. In this study, SLIPSs have been obtained on practically important aluminum with a porous anodic alumina layer by impregnating lubricants containing organic additives. The additive-containing lubricants change the surface slippery even without prior organic coating of the porous alumina surface. The additive-containing SLIPSs reveal a low water sliding angle of <5° and markedly improved corrosion resistance in an acetic acid solution containing chloride. The SLIPSs are formed by the in situ adsorption of the organic additives on the porous alumina surface. The scratched defects induce corrosion of the organic coating-type SLIPSs, whereas the additive-containing SLIPSs sustain high corrosion resistance even after introducing scratch defects. The adsorption of the organic additive in lubricants and refilling of the lubricant are responsible for the self-healing of the corrosion resistance. Thus, the additive-containing SLIPSs are promising self-healing corrosion-resistant surfaces.
• Fabrication of superhydrophobic copper metal nanowire surfaces with high thermal conductivity

  Ryota Yamamoto, Damian Kowalski, Ruijie Zhu, Keisuke Wada, Yuki Sato, Sho Kitano, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  APPLIED SURFACE SCIENCE 537 2021年01月 

  Copper is an important practical metal with a high thermal conductivity that is widely used as a heat exchanger material. However, a liquid film often forms on the Cu surface through water vapor condensation, causing a large resistance to heat transfer. To address this issue, a superhydrophobic Cu metal nanowire surface is developed herein via Cu anodizing in a KOH electrolyte to form Cu(OH)(2) nanowires, followed by hydrogen reduction at an elevated temperature and the application of a wet organic coating. The hydrogen treatment reduces the hydroxide to the metal while maintaining the nanowire morphology. The superhydrophobic Cu metal nanowire surface exhibits effective removal of water droplets formed through water vapor condensation. Furthermore, the metal nanowire surface exhibits highly improved heat transfer compared with the Cu(OH)(2) nanowire surface. Therefore, the combined process of anodizing and hydrogen reduction is a simple approach that forms an effective superhydrophobic Cu surface with high thermal conductivity.
• The effect of an anode functional layer on the steam electrolysis performances of protonic solid oxide cells

  Chunmei Tang, Katsuya Akimoto, Ning Wang, Laras Fadillah, Sho Kitano, Hiroki Habazaki, Yoshitaka Aoki

  Journal of Materials Chemistry A 9 24 14032 - 14042 2021年 

  Protonic solid oxide steam electrolysis cells (P-SOECs) based on BaZrxCe0.8−xYb0.1Y0.1O3−δproton conductors are promising to produce “green” hydrogen from renewable energy at intermediate temperatures. Herein, we demonstrate that the electrolysis performances of a cell with a high-Zr-content electrolyte, BaZr0.6Ce0.2Y0.1Yb0.1O3−δ(BZCYYb6211), can be significantly improved by using a La0.5Sr0.5CoO3−δ(LSC) thin film (∼90 nm) as an anode functional layer (AFL). Electrochemical measurements indicated that LSC-AFL significantly reduced the barrier height for the electrochemical proton incorporation reaction at the gas-electrolyte-electrode triple-phase boundary. Hence, both the ohmic and polarization resistances of the BZCYYb6211 cell decreased from 0.52 and 0.98 Ω cm2to 0.26 and 0.57 Ω cm2, respectively, with the LSC-AFL at 600 °C. In addition, the BZCYYb6211 cell achieved a high electrolysis current of 1.22 A cm−2at 1.3 V with a Faraday efficiency of approximately 80%, which was equivalent to that (1.13 A cm−2) of the cell with a state-of-the-art electrolyte BaZr0.1Ce0.7Y0.1Yb0.1O3−δ(BZCYYb1711). BZCYYb6211 with LSC-AFL showed good durability at 500 °C under high steam conditions with an applied current of 1 A cm−2for 100 h. These results revealed that the introduction of an AFL is an effective method to obtain P-SOECs with excellent performances and durability.
• A lithiophilic carbon scroll as a Li metal host with low tortuosity design and “Dead Li” self-cleaning capability

  Ruijie Zhu, Huijun Yang, Laras Fadillah, Zetao Xiong, Damian Kowalski, Chunyu Zhu, Sho Kitano, Yoshitaka Aoki, Hiroki Habazaki

  Journal of Materials Chemistry A 9 22 13332 - 13343 2021年 

  On the way to achieve a practical lithium (Li) metal anode for next-generation batteries, the formation and accumulation of inactive “Dead Li” is an unavoidable issue. The accumulation of “Dead Li” leads to increased internal mass-transfer resistance which seriously deteriorates the performance of Li metal batteries during long-term cycling. In this study, by accommodating Li metal into a copper oxide coated carbon scroll host with a vertically aligned framework which possesses a unique low-tortuosity structure, the cycling stability of the Li anode can be significantly improved. It is demonstrated that the mass-transfer resistance and the concentration polarization near the Li metal surface can be greatly alleviated by using this low-tortuosity anode structure design. “Dead Li” that is formed on the electrode surface can automatically fall into the inner tunnel of the carbon host, endowing the anode with the capability of “Dead Li” self-cleaning. As a result, our new Li electrode can remain electrochemically active even after 1000 h in a symmetric cell measurement from 1 mA cm−2to 1 mA h for 500 cycles. The as-reported structure design of the Li anode in this work is compatible with most of the modification technologies that have been applied to conventional Li foil electrodes, providing this new Li anode with a great potential to be applied in subsequent Li anode studies.
• In Situ Activation of Anodized Ni–Fe Alloys for the Oxygen Evolution Reaction in Alkaline Media

  Naohito Yamada, Sho Kitano, Yuya Yato, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  ACS Applied Energy Materials 3 12 12316 - 12326 2020年12月28日 [査読有り]
   

  A simple anodizing technique has been employed to develop highly active electrocatalysts that can be applied to the oxygen evolution reaction (OER) in alkaline media. NiFe alloys were electrodeposited and anodized to form a porous electrocatalytic layer. This approach produces highly active electrodes without the need for noble metals, binders, or conductive carbon additives. The as-anodized electrode initially exhibits poor OER activity in 1.0 mol dm(-3) KOH; however, the effects of potential cycling improve the OER activity to an extent that an overpotential as low as 0.26 V at 10 mA cm(-2) is observed for the anodized Ni-11.8 at. % Fe electrode. Although significant in situ activation is achieved with anodized NiFe electrodes, this activation is less significant for as-deposited NiFe or anodized Ni electrodes. Furthermore, OER activity is observed to be composition-dependent, with the Ni-11.8 at. % Fe electrode exhibiting the greatest activity. A porous fluoride-rich, Fe-doped Ni oxyfluoride layer produced by anodizing is converted via potential cycling to an amorphous or poorly crystalline Fe-doped Ni(OH)(2) layer with a nanoflake-like morphology. The high activity is maintained even after the removal of most of the fluoride. Thus, the F-rich, Fe-doped Ni oxyfluoride is a promising precursor to develop a highly active OER electrode.
• Compositional variations in anodic nanotubes/nanopores formed on Fe 100, 110 and 111 single crystals

  Laras Fadillah, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  Electrochimica Acta 364 137316 - 137316 2020年12月 

  Anodizing of iron (100), (110) and (111) single crystals in mono-ethylene-glycol electrolyte containing 1.5 mol dm−3 water and 0.1 mol dm−3 ammonium fluoride leads to formation of anodic iron nanopores/nanotubes where the nanopores are essentially composed of oxide nanotubes separated by iron fluoride matrix. It was found that electrochemical thermodynamics for nanoporous/nanotubular film formation apparently depends on the index number of facet on which the anodic film is formed. The film formation on (100) facet is associated with extended gas evolution upon anodizing and consequently corresponds to a shift of current-time curve towards higher current density values comparing with those formed on higher index number facets. The nanotubes formed on (100) facet have a general chemical formula of Fe2O3.FeF2, whereas those formed on higher index number are composed of Fe3O4.FeF2. The anodic films formed on Fe (110) and Fe (111) are essentially amorphous whereas the one formed on (100) facet shows high degree of crystallinity. The results are discussed in view of anisotropic properties of iron.
• Spinel-type metal oxide nanoparticles supported on platelet-type carbon nanofibers as a bifunctional catalyst for oxygen evolution reaction and oxygen reduction reaction

  Yuki Sato, Sho Kitano, Damian Kowalski, Yoshitaka Aoki, Naoko Fujiwara, Tsutomu Ioroi, Hiroki Habazaki

  Denki Kagaku 88 6 566 - 573 2020年11月05日 

  Development of highly active bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is required for air electrodes of zinc-air secondary batteries (ZAB). In this study, we synthesize spinel-type MnCo2O4 (MCO) nanoparticles on highly graphitized platelet-type carbon nanofibers (pCNF) via a solvothermal method. The pCNF is selected as carbon support in this study because of the excellent stability against anodic degradation under the OER condition. The MCO nanoparticles of 2–5 nm in diameter are uniformly dispersed on pCNF and the catalyst exhibits high activities for ORR due to strong interaction pCNF and MCO, in addition to the improvement of OER activities. The MCO/carbon hybrids show comparable electrocatalytic performances to state-of-the-art bifunctional electrodes for OER and ORR.
• Formation of quasi-spherical Au48-198 clusters in anodic titania nanotubes grown on Ti-Au alloys

  M. Sepúlveda, J.G. Castaño, F. Echeverría, Y. Aoki, D. Kowalski, H. Habazaki

  Electrochemistry Communications 120 106847  2020年11月 [査読有り]
   

  The effect of alloying sputter-deposited Ti with 2 at.% of Au on the growth of anodic nanotubes was studied in monoethylene glycol electrolyte containing 1.0 mol dm−3 of water and 0.1 mol dm−3 of ammonium fluoride. The classic shape of nanotubes modified with quasi-spherical clusters of Au48-198 was obtained on Ti-Au (2 at.%). The results were compared to the formation of a barrier-type anodic film which suggested that gold located at the alloy/anodic film interface is enriched as a consequence of the preferential oxidation of titanium during the prior anodizing period and transported to the cell boundary region of the nanotubular film in the form of quasi-spherical clusters of Au48-198. A consequence of the inclusion of Au48-198 in the structure of the nanotubes was a reduction in the rate of nanotubular film growth due to the generation of oxygen catalysed on the clusters. A further increase in gold content up to 8 at.% in the alloy resulted in the formation of sponge-like or nanoporous anodic layers, with the structure depending on electrolyte composition.
• Fluorine‐Free Slippery Liquid‐Infused Porous Surfaces Prepared Using Hierarchically Porous Aluminum

  T. Inoue, A. Koyama, D. Kowalski, C. Zhu, Y. Aoki, H. Habazaki

  Phys. Status Solidi A 217 13 1900836  2020年10月 [査読有り]
   

  Slippery liquid-infused porous surfaces (SLIPS) have been receiving increased attention. Fluorinated compounds have been used to prepare SLIPS, but because of bioaccumulation and ecological impact of perfluoroalkyl building blocks, the fluorine-free SLIPS (F-free SLIPS) system is preferable for practical applications. Herein, SLIPS are prepared from a hierarchically porous aluminum substrate, tetradecylphosphonic acid monolayer coating, and silicone lubricant oil. The several properties of the SLIPS, including durability against lubricant loss, ice adhesion, and corrosion resistance, are compared with those with a fluoroalkyl monolayer coating and fluorinated lubricant oil. The findings demonstrate that the F-free SLIPS show higher durability against the removal of lubricant in air and also in water. Both fluorinated SLIPS (F-SLIPS) and F-free SLIPS samples exhibit extremely reduced ice adhesion compared with superhydrophobic surfaces obtained using the same hierarchically porous aluminum substrate with fluorinated or fluorine-free monolayer coating. The SLIPS samples have very high corrosion resistance in NaCl solution but not in alkaline solution. The solution-dependent corrosion resistance is discussed in terms of the stability of monolayer coating.
• Highly Durable Oxygen Evolution Reaction Catalyst: Amorphous Oxyhydroxide Derived from Brownmillerite-Type Ca2FeCoO5

  Yuki Sato, Yoshitaka Aoki, Kentaro Takase, Hisao Kiuchi, Damian Kowalski, Hiroki Habazaki

  ACS Applied Energy Materials 3 6 5269 - 5276 2020年06月22日 [査読有り][通常論文]
  
• Spinel-type metal oxide nanoparticles supported on platelet-type carbon nanofibers for OER/ORR

  Y. Sato, S. Kitano, D. Kowalski, Y. Aoki, N. Fujiwara, T. Ioroi, H. Habazaki

  Electrochemistry (Tokyo) 88 6 566 - 573 2020年06月 [査読有り]
  
• Characterization of Dark-Colored Nanoporous Anodic Films on Zinc

  R. Masuda, D. Kowalski, S. Kitano, Y. Aoki, T. Nozawa, H. Habazaki

  Coatings 10 11 1014 - 1021 2020年05月 [査読有り]
  
• A widely applicable strategy to convert fabrics into lithiophilic textile current collector for dendrite-free and high-rate capable lithium metal anode

  Ruijie Zhu, Chunyu Zhu, Nan Sheng, Zhonghao Rao, Yoshitaka Aoki, Hiroki Habazaki

  CHEMICAL ENGINEERING JOURNAL 388 15 2020年05月 [査読有り]
   

  Hindered by dendrite growth, unceasing volume change and repeated regeneration of solid-state electrolyte interface, the practical application of lithium (Li) metal anode is still facing challenges from low Coulombic efficiency (CE), insufficient safety performance and poor cyclic stability. Current collector plays a key role in regulating Li deposition and suppressing dendrite growth. In this report, through a simple bio-template method, a textile-structured nickel (Ni) framework is fabricated as current collector for Li metal anode, whose unique micro-nano hierarchical structure is adequate for accommodating Li. A good performance after more than 200 cycles at 3 mA cm(-2) during repeated Li plating/stripping is remained in virtue of this unique structure design. By further introducing Ag2S nanoparticles uniformly to the current collector, a dendrite-free and high reversible Li metal anode is achieved, showing low over-potential (similar to 24 mV at 1 mA cm(-2)), high CE (similar to 98%) and excellent quick charging/discharging stability (up to 350 cycles at 10 mA cm(-2) in symmetric cell). Furthermore, this new strategy for constructing textile-structured metallic framework opens a foreground for various applications of porous metals.
• Long-term durability of platelet-type carbon nanofibers for OER and ORR in highly alkaline media

  Yuki Sato, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  Applied Catalysis A: General 597 117555 - 117555 2020年05月 [査読有り][通常論文]
  
• Anisotropically enhanced heat transfer properties of phase change material reinforced by graphene-wrapped carbon fibers

  Nan Sheng, Ruijie Zhu, Takahiro Nomura, Zhonghao Rao, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki, Tomohiro Akiyama

  Sol. Energy Mater Sol. Cells 206 110280 - 110280 2020年03月 [査読有り]
   

  Organic phase change materials (PCM, such as paraffin) are broadly used in thermal energy storage systems, especially for the efficient utilization of solar energy and industrial waste heat, whereas their low shape-stability and poor heat transfer performance have hindered the practical applications. In this work, we aim at producing high-performance phase change composites (PCCs) with high, anisotropic thermal conductivity and good shape-stability. The PCCs are supported by a biomass-derived porous carbon scaffolds, which are constructed with graphene-wrapped and vertically aligned hollow carbon fibers. The PCC with a filler content of 8.5 wt% exhibits a high lateral thermal conductivity of 1.36 W m(-1) k(-1) and an even higher thermal conductivity of 2.68 W m(-1) K-1 along the axial fiber direction which is 10.7-fold higher than pure paraffin. The PCCs also show satisfactory shape stability, high latent heat, good thermal cycling and chemical stability. These results demonstrate the potential for fast thermal energy conversion and management using our novel carbon scaffold supported PCCs with tailored anisotropic thermal transfer properties.
• Proton Pumping Boosts Energy Conversion in Hydrogen-Permeable Metal-Supported Protonic Fuel Cells

  SeongWoo Jeong, Tomoyuki Yamaguchi, Mamoru Okamoto, Chunyu Zhu, Hiroki Habazaki, Masaharu Nagayama, Yoshitaka Aoki

  ACS Applied Energy Materials 3 1 1223 - 1234 2020年01月27日 [査読有り][通常論文]
   

  Protonic ceramic fuel cells (PCFCs) have limited application below 500 degrees C owing to their high ohmic and polarization resistances. Hence, efforts are ongoing to develop advanced fuel cells based on semiconductor device science as well as material interfacial engineering. Here, we demonstrate that hydrogen-permeable metal-supported fuel cells (HMFCs) exhibit improved energy conversion efficiency at relatively lower temperatures due to the retardation of secondary conduction (that of the oxide ions) at the oxide/metal heterointerface. The electrolyte membrane in HMFCs is forced to gain extra protons to compensate for the charge from the oxide ions accumulating via blocking, resulting in extremely high proton conductivity. Simultaneously, the heavily hydrated membrane pumps protons out of the cathode side during cell operation. This significantly promotes interfacial proton diffusion for cathode reactions. Hence, HMFCs can operate at high efficiency even at temperatures lower than the operational temperature of PCFCs and will help improve the power generation performance of protonic oxide fuel cells at temperatures lower than 500 degrees C.
• Prognostic impact of sustained new-onset atrial fibrillation in critically ill patients

  Takuo Yoshida, Shigehiko Uchino, Yusuke Sasabuchi, Yasuhiro Hagiwara, Tomonao Yoshida, Hiroshi Nashiki, Hajime Suzuki, Hiroshi Takahashi, Yuki Kishihara, Shinya Nagasaki, Tomoya Okazaki, Shinshu Katayama, Masaaki Sakuraya, Takayuki Ogura, Satoki Inoue, Masatoshi Uchida, Yuka Osaki, Akira Kuriyama, Hiromasa Irie, Michihito Kyo, Nozomu Shima, Junichi Saito, Izumi Nakayama, Naruhiro Jingushi, Kei Nishiyama, Takahiro Masuda, Yasuyuki Tsujita, Masatoshi Okumura, Haruka Inoue, Yoshitaka Aoki, Takashiro Kondo, Isao Nagata, Takashi Igarashi, Nobuyuki Saito, Masato Nakasone

  INTENSIVE CARE MEDICINE 46 1 27 - 35 2020年01月 

  Purpose The development of new-onset atrial fibrillation (AF) in critically ill patients may be associated with poor outcomes. However, it is unknown whether sustained new-onset AF contributes to worse outcome. The aim of this study was to assess whether sustained new-onset AF is associated with stroke and death and to look for a possible dose-response relationship between AF duration and death. Methods In a prospective cohort study conducted in 32 intensive care units in Japan from 2017 to 2018, we enrolled adult patients with new-onset AF. We compared patients with AF duration longer than 48 h with those with AF duration shorter than 48 h. To assess a dose-response relationship between AF duration and hospital mortality, we conducted landmark analysis and time-dependent Cox regression analysis. Results Among a total of 423 new-onset AF patients, hospital mortality was 25%, and the incidence of in-hospital stroke was 4.6%. AF duration longer than 48 h was not independently associated with hospital mortality (adjusted odds ratio: 1.52; 95% Confidence Interval: 0.87-2.64). The incidence of in-hospital stroke was 7.6% in patients with AF duration longer than 48 h and 3.8% in those with AF duration shorter than 48 h (p = 0.154). When analyzing time more continuously, we observed a time-dependent association between AF duration and hospital mortality (p = 0.005 by landmark analysis and p = 0.019 by Cox analysis). Conclusions Sustained new-onset AF was time-dependently associated with hospital mortality in ICU patients, albeit with some uncertainty since AF duration longer than 48 h was not independently associated with in-hospital death or stroke.
• Mixed proton–electron–oxide ion triple conducting manganite as an efficient cobalt-free cathode for protonic ceramic fuel cells

  Ning Wang, Satoshi Hinokuma, Toshiaki Ina, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Journal of Materials Chemistry A 8 21 11043 - 11055 2020年 [査読有り][通常論文]
   

  Cubic La_0.7Sr_0.3Mn_1−xNiyO_3−δ undergoes the hydration reaction with the charge disproportionation between Mn and O atoms, and thus, can reduce the interfacial polarization of protonic solid oxide cells due to the H⁺/O²⁻/e⁻ triple conductivity.

• Employing a T-shirt template and variant of Schweizer's reagent for constructing a low-weight, flexible, hierarchically porous and textile-structured copper current collector for dendrite-suppressed Li metal

  Ruijie Zhu, Nan Sheng, Zhonghao Rao, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  JOURNAL OF MATERIALS CHEMISTRY A 7 47 27066 - 27073 2019年12月 

  The utilization of a Li metal anode is necessary in the development of next generation high energy density Li batteries, which is still hindered by problems of dendrite growth, volume change and electrolyte depletion. To overcome these difficulties, the employment of 3D porous current collectors has been demonstrated to be an effective strategy. However, the widely used porous metallic current collectors, such as commercial Cu foam, are always too heavy to meet the demand for high energy density. In this work, we develop a low-weight, flexible, hierarchically porous and textile-structured Cu current collector via a smart cotton T-shirt template method. By employing a variant of Schweizer's reagent as the Cu source, the T-shirt moulded Cu framework can inherit the textile morphology. The hierarchically porous structure and high surface area can lower the local current density, and the unique 3D structure can confine the growth of Li crystals, all of which can endow the novel textile-structured Cu with superior performance as a current collector for Li metal anodes. Furthermore, this strategy provides a convenient route for designing template-structured frameworks, which is useful not only for the development of a current collector, but also for the preparation of numerous structure-oriented materials.
• Ultra-rapid formation of crystalline anatase TiO2 films highly doped with substrate species by a cathodic deposition method

  Yuki Sato, Hikaru Kobayashi, Damian Kowalski, Akira Koyama, Chunyu Zhu, Yoshitaka Aoki, Mikito Suto, Hiroki Habazaki

  Electrochemistry Communications 108 106561 - 106561 2019年11月 

  The formation of crystalline anatase films having important applications such as photocatalysis, solar cells, electrochromic applications, and bio-implants requires time-consuming multiple processes including heat treatments. In this paper, ultra-rapid formation of a crystalline anatase film on a tin substrate is realized by a cathodic deposition method, which is performed only for 3 s in an aqueous solution containing TiF62- at 60 degrees C without any heat treatment. The deposited nanocrystalline anatase film of similar to 90 nm thickness contains high concentration of tin species derived from the substrate metal and shows superhydrophilicity after UV light irradiation. The process utilized in this study provides a novel annealing-free approach for the rapid formation of a photoactive crystalline anatase film on heat-labile substrates.
• Incorporation of Bulk Proton Carriers in Cubic Perovskite Manganite Driven by Interplays of Oxygen and Manganese Redox

  Ning Wang, Satoshi Hinokuma, Toshiaki Ina, Hajime Toriumi, Misaki Katayama, Yasuhiro Inada, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Chemistry of Materials 31 20 8383 - 8393 2019年10月22日 [査読有り][通常論文]
   

  Mixed proton-electron conductors (MPECs) are indispensable for the efficient operation of proton conducting ceramic fuel cells and electrolyzer cells at intermediate temperatures (below 500 degrees C), but robust guidelines for their material design are still missing. Here, this study for the first time reports on the massive uptake of proton carriers in cubic perovskite type La0.7Sr0.3MnO3-delta at intermediate temperatures through the hydration reaction triggered by the coupled oxygen and manganese redox reaction. La0.7Sr0.3MnO3-delta undergoes decline of antibonding O 2p states hybridized with Mn 3d orbitals together with oxidation of Mn3+ to Mn4+ by hydration and thus retains bulk protons in the concentrations of 0.14 in wet air at around 420 degrees C, which is corresponding to the concentration of the well-known proton conductor BaZrxCe0.8-xY0.2O3-delta. The current results offer a general concept to design MPECs operating in air conditions, namely, that transition metal oxides possessing many oxygen vacancies and oxygen hole carriers could be promising candidates.
• Vertically aligned carbon fibers as supporting scaffolds for phase change composites with anisotropic thermal conductivity and good shape stability

  Nan Sheng, Ruijie Zhu, Kaixin Dong, Takahiro Nomura, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki, Tomohiro Akiyama

  Journal of Materials Chemistry A 2019 7 4934 - 4940 2019年09月 [査読有り][通常論文]
   

  The wide application of organic phase change materials for thermal energy storage and management is limited by their low thermal conductivity and poor shape stability. In this work, anisotropic thermally conductive and shape-stabilized phase change composites (PCCs) were successfully prepared with vertically aligned carbon fibers as supporting scaffolds. The aligned and hollow carbon fiber scaffolds with different densities were facilely fabricated by the direct carbonization of rolled cotton sheets with aligned and hollow cellulose fibers. PCCs were obtained by vacuum impregnation of paraffin wax. Because of the interconnected hollow carbon fiber frameworks with vertically aligned fibers and high porosity, PCCs present enhanced anisotropic thermal conductivity and good shape stability against leakage. The thermal conductivity in the axial direction along the fibers is higher than that in the lateral direction, since the aligned fiber scaffolds act as the thermal conduction pathway. The thermal conductivity of a PCC with a carbon ratio of 8.8 wt% is 0.77 W K-1 m(-1) (>3 times that of pure paraffin) in the axial direction, while the value in the lateral direction is 0.58 W K-1 m(-1). This work provides a novel strategy for designing anisotropic thermally conductive and shape-stabilized PCCs with potential applications in advanced thermal management and storage.
• Activation of Catalytically Active Edge-Sharing Domains in Ca2FeCoO5 for Oxygen Evolution Reaction in Highly Alkaline Media

  Damian Kowalski, Hisao Kiuchi, Teruki Motohashi, Yoshitaka Aoki, Hiroki Habazaki

  ACS Applied Materials & Interfaces 11 32 28823 - 28829 2019年08月14日 

  Rechargeable zinc-air batteries are considered as one of the possible candidates to replace conventional lithium-ion batteries. One of the requirements for effective battery operation is an oxygen evolution reaction (OER) that needs to be generated in a highly alkaline electrolyte. The A(2)BB'O-5 brownmillerite-type Ca2FeCoO5 electrocatalyst having a 57 Pbcm symmetry exhibits very high electrocatalytic activity toward OER in 4 mol dm(-3) KOH. Our studies show that the electrocatalyst undergoes bulk amorphization upon OER and adequately activates catalytically active domains. The synchrotron radiation studies using the extended X-ray absorption fine structure (EXAFS) technique show that the central structural unit found in the polarized Ca2FeCoO5 is a cluster of edge-sharing CoO6 octahedra. The OER preferentially takes place on the edge-sharing CoO6 octahedra catalytic centers reconstructed in the brownmillerite-type electrocatalyst. The EXAFS second shell peaks at an interatomic distance of 2.8 angstrom are the fingerprints of the catalytically active domains.
• Heteroatom-doped porous carbon with tunable pore structure and high specific surface area for high performance supercapacitors

  Cheong Kim, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  Electrochimica Acta 314 173 - 187 2019年08月10日 [査読有り][通常論文]
   

  © 2019 Elsevier Ltd Biomass-derived porous carbons with very high specific surface area (SSA) and heteroatom-doping are important for obtaining high performance supercapacitor. In this study, we report a simple and straightforward strategy, which involves the efficient and exothermic pyrolysis of Mg/K/Mg·K-nitrate-urea-cellulose mixture with subsequent high temperature carbonization and washing treatment, to produce N-doped porous carbon with tunable pore structure. The vigorous exothermic pyrolysis of Mg/K/Mg·K-nitrate-urea-cellulose induces the formation of large macropores. The subsequent high temperature carbonization and washing treatments remove Mg,K compounds and facilitate the creation of numerous micro and mesopores. The pore size distribution of the obtained carbon is quite dependent on the Mg·K ratio in the precursors. In this manner, the three-dimensional hierarchical porous carbon with SSA larger than 2700 m2 g−1 is obtained. The obtained porous carbon as the electrodes for supercapacitor in two-electrode measurement shows high specific capacitance (279 F g−1 at 1 A g−1 in a 6 M KOH electrolyte), excellent cycling stability (larger than 89% capacitance retention after 10,000 cycles at 2 A g−1) and good rate capability (235 F g−1 at even 30 A g−1). These results indicate that biomass cellulose-derived heteroatom-doped hierarchical porous carbon is a promising material for supercapacitor.
• The role of tungsten species in the transition of anodic nanopores to nanotubes formed on iron alloyed with tungsten

  Fadillah Laras, Takase Kentaro, Kobayashi Hikaru, Turczyniak-Surdacka Sylwia, Strawski Marcin, Kowalski Damian, Zhu Chunyu, Aoki Yoshitaka, Habazaki Hiroki

  ELECTROCHIMICA ACTA 309 274 - 282 2019年06月20日 [査読有り][通常論文]
   

  The effect of alloying of sputter-deposited Fe with 9 at.% tungsten on the growth of nanoporous anodic oxide was studied in ethylene glycol electrolyte containing 0.1 mol dm(-3) ammonium fluoride and 1.5 mol dm(-)(3) water. The classic nanoporous anodic film (Al2O3-like) was developed on pure Fe while the transition of nanopores to nanotubes (TiO2-like) was observed for anodizing of Fe-W alloy. The pores/ nanotubes having average diameter 50-110 nm and 30-60 nm on pure Fe and Fe-W alloy anodized at voltage 40-60 V, respectively. Both nanoporous/nanotubular anodic films grow in line with the field assisted flow model with a few fundamental details: i) transition of nanopores to nanotubes is observed upon anodizing of Fe-W alloy, ii) significant reduction of the cell size (nanotube diameter) is obtained on Fe-W alloy, iii) relatively thick layer is produced at Fe-W alloy/oxide interface. The primary reason of this transition to nanotubes as well as chemical changes is discussed in view of effective modification of the cell boundary region with tungsten species, probably WF6 compound, upon growth of anodic film under influence of high electric field strength. The possible reason of developing the space in between nanotubes is faster kinetics of WF6 reaction with water over the presence of low solubility FeFx species. Alloying of iron is one of the effective ways to modify the nanostructure of the anodic film on iron. (C) 2019 Elsevier Ltd. All rights reserved.
• Exothermically Efficient Exfoliation of Biomass Cellulose to Value-Added N-Doped Hierarchical Porous Carbon for Oxygen Reduction Electrocatalyst

  Cheong Kim, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  Industrial & Engineering Chemistry Research 58 8 3047 - 3059 2019年02月27日 [査読有り][通常論文]
   

  © 2019 American Chemical Society. In this work, high-value-added N-doped hierarchical porous carbon (NHPC) for oxygen reduction reaction (ORR) electrocatalysis was prepared using biomass cellulose as the raw material. The pyrolysis of cellulose is accelerated by a redox combustion reaction of magnesium nitrate-carbohydrates (urea and cellulose) as absorbed in cellulose fibers, which endows doping with nitrogen, exfoliates the cellulose to highly porous particles, and creates numerous pores simultaneously. After being further carbonized at high temperature and washed with acid, NHPCs were produced that have hierarchical porous structure and large specific surface area. These features are beneficial to the ORR. The influence of four preparation parameters, including species of magnesium salt, carbonization temperature, urea amount, and magnesium salt amount, on the porous characteristics and ORR performance is comprehensively investigated.
• Fabrication of superoleophobic surface on stainless steel by hierarchical surface roughening and organic coating

  Atsushi Kasuga, Akira Koyama, Katsutoshi Nakayama, Damian Kowalski, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  ISIJ International 59 2 345 - 350 2019年02月01日 [査読有り][通常論文]
   

  © 2019 ISIJ. Stainless steels is practically important corrosion-resistant metallic materials, and additional surface functionalities including self-cleaning, anti-fouling, anti-ice and snow sticking and fluid drag reduction by the introduction of superhydrophobic and superoleophobic surfaces are of recent interest. Here, we report the micro-/nano-hierarchical roughening of type 304 stainless steel surface by chemical and electrochemical etching and anodizing. Chemical etching in HCl + FeCl 3 aqueous solution containing a surfactant introduces surface roughness of several tens micrometers scale and the electrochemical etching in HCl + HNO 3 aqueous solution produces a number of etch pits of ~1 μm in size. Then, a porous anodic layer of the pore size of ~20 nm is formed on the etched surface by anodizing in ethylene glycol electrolyte containing 0.1 mol dm −3 NH 4 F and 0.1 mol dm −3 H 2 O. After fluoroalkylsilane (FAS) coating of the hierarchically rough surface to reduce the surface energy, the surface becomes superhydrophobic and superoleophobic; the advanced contact angle for hexadecane (surface tension of 27.6 mN m −1 ) is ~160° and the contact angle hysteresis is less than 10°. Since the FAS-coated flat surface is oleophilic, so that such hierarchically rough surface is of significant importance to achieve the superoleophobicity even for low surface tension liquids.
• Origins of high power outputs in hydrogen permeable metal-support fuel cells

  Y. Aoki, S. Jeong, M. Nagayama, C. Zhu, H. Habazaki

  ECS Transactions 91 1 917 - 920 2019年 

  In general, protonic ceramic fuel cells (PCFCs) have structure of porous anode support composed of proton-conducting ceramic and metallic Ni. The porous anode type PCFCs have much lower power outputs than expected from the proton conductivity of electrolyte materials. Meanwhile, PCFCs with hydrogen-permeable dense metal anode, hydrogen-permeable metal-supported fuel cells (HMFCs), have reported outstanding power outputs even at 400oC with significantly lowered ohmic resistances despite the analogous electrolyte materials. Obscure is, however, what makes such different cell properties. In this study, we examined the electrochemical performances of both type of cells at around 500oC.
• Intermediate temperature H+-SoEC with proton conducting BaZr0.6Ce0.2Y0.2O3-δ electrolyte

  H. Toriumi, C. Zhu, H. Habazaki, Y. Aoki

  ECS Transactions 91 1 2669 - 2672 2019年 

  BaCe0.8Y0.2O3-δ (BCY) has high proton conductivity but is less stable against CO2 and steam. The solid solution BaZrxCe1-x-yYyO3-δ (BZCY) tend to be more tolerant to CO2 and steam with increasing Zr contents. In this work, cathode-supported thin film cell was fabricated using BaZr0.6Ce0.2Y0.2O3-δ with higher Zr contents for the electrolyte of proton conducting solid oxide steam electrolysis cell (H+-SOEC). The cell composed of LSCF|BZCY622|Ni-BZCY622 yielded electrolysis currents of 330 and 200 mA cm-2 at 700 and 600ºC, respectively, at 1.5 V bias.
• High dispersion and oxygen reduction reaction activity of Co3O4 nanoparticles on platelet-type carbon nanofibers

  Naohito Yamada, Damian Kowalski, Akira Koyama, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  RSC Advances 9 7 3726 - 3733 2019年 [査読有り][通常論文]
   

  © The Royal Society of Chemistry. In this study, platelet-type carbon nanofibers prepared by the liquid phase carbonization of polymers in the pores of a porous anodic alumina template were used to prepare the Co 3 O 4 /carbon electrocatalysts. For comparison, Co 3 O 4 nanoparticles were also deposited on multiwall carbon nanotubes (MWCNTs). Both the nitrogen-free platelet-type carbon nanofibers (pCNFs) and the nitrogen-containing analogue (N-pCNFs) exhibited better dispersion and higher amount of deposited Co 3 O 4 nanoparticles compared to the MWCNTs. In addition, many individual Co 3 O 4 nanoparticles were deposited separately on pCNF and N-pCNF, whereas aggregated deposition was commonplace on MWCNTs. The results indicated that the side wall of the pCNFs, which consisted of carbon edge planes, was the preferential nucleation site of Co 3 O 4 nanoparticles rather than the basal planes of carbon that predominated the surface of the MWCNTs. The oxygen reduction reaction (ORR) activity of the Co 3 O 4 /pCNF composite in 0.1 mol dm −3 KOH solution was better than that of Co 3 O 4 /MWCNTs. The N-pCNF further enhanced the ORR activity of the Co 3 O 4 /pCNFs even though the dispersion and supported amount of Co 3 O 4 nanoparticles were negligibly affected by the presence of the nitrogen species. Synergistic interactions of the Co 3 O 4 nanoparticles with N-doped CNFs contributed to the increased ORR activity.
• High-valence-state manganate(v) Ba3Mn2O8 as an efficient anode of a proton-conducting solid oxide steam electrolyzer

  Hajime Toriumi, Taisei Kobayashi, Satoshi Hinokuma, Toshiaki Ina, Takashi Nakamura, Koji Amezawa, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Inorganic Chemistry Frontiers 6 6 1587 - 1597 2019年 [査読有り][通常論文]
   

  Herein, high-valence-state Mn(v) oxide, barium manganate(v) (Ba-3(MnO4)(2)), is examined as an anode electrocatalyst of a H+-conducting solid oxide steam electrolysis cell (H-SOEC). Ba-3(MnO4)(2) comprises C-3v-symmetric MnO43- oxo-anions with three long Mn-O bonds and one short Mn-O bond at room temperature. Ba-3(MnO4)(2) caused a conductivity jump by one order of magnitude at approximately 600 degrees C owing to the antiferromagnetic/paramagnetic phase transition, accompanied by a shape change of the tetrahedral MnO43- anions from C-3v to T-d symmetry, as confirmed by the electrical conductivity measurements and the extended X-ray absorption fine structure at an elevated temperature. Hence, the Ba-3(MnO4)(2) base anode of the H-SOEC exhibited improved performance, with anode polarization resistances being lower than those of Sm0.5Sr0.5CoO3, a well-known H-SOEC anode material. Impedance analysis in terms of oxygen and water partial pressure revealed that the superior performance of the Ba-3(MnO4)(2) base anode can be attributed to the extended reaction area. Since abundant unoccupied 3d states of the high-valence-state Mn5+ cations are favorable for charge transfer interactions with water electron donors, thereby facilitating water adsorption, the oxygen evolution reaction could occur directly over the electrode surface, and thus the reaction sites were not limited to the gas-electrode-electrolyte triple phase boundary.
• La0.7Sr0.3Mn1−xNixO3−δ electrocatalysts for the four-electron oxygen reduction reaction in concentrated alkaline media

  Y. Aoki, E. Tsuji, T. Motohashi, D. Kowalski, H. Habazaki

  Journal of the Physical Chemistry C 122 39 22301 - 22308 2018年10月04日 [査読有り][通常論文]
   

  Electrocatalytic activity for the four-electron-transfer oxygen reduction reaction (ORR) was examined with perovskite-type La0.7Sr0.3Mn1-xNixO3-delta (x = 0-0.5) compounds in concentrated KOH. Electrochemical measurements by means of a rotating ring-disk electrode technique revealed that 10% substitution of Mn by Ni atoms significantly improved ORR activity whereas further Ni substitution significantly decreased the catalytic performance. Moreover, La0.7Sr0.3Mn0.9Ni0.1O3-delta could achieve the ideal reaction electron number (similar to 4) without the aid of carbon additives, whereas compounds with x > 0.1 achieved a number less than 4 in the absence of carbon cocatalysts, attributed to lowered reaction rates related to two-electron reduction from oxygen to peroxide. Combined with the results of X-ray photoelectron spectroscopy, the pronounced catalytic activity of La0.7Sr0.3Mn0.9Ni0.1O3-delta could be correlated with the population of Mn3+ states with (e(g))(1) configuration.
• Nitrogen-doped porous carbon as-mediated by a facile solution combustion synthesis for supercapacitor and oxygen reduction electrocatalyst

  Chunyu Zhu, Manami Takata, Yoshitaka Aoki, Hiroki Habazaki

  CHEMICAL ENGINEERING JOURNAL 350 278 - 289 2018年10月 [査読有り][通常論文]
   

  Porous carbon has attracted great interest because of its distinctive structure and superior properties for designing electrochemical energy storage devices. In this work, we report a novel and facile method to fabricate nitrogen-doped porous carbon (NPC) with designed hierarchical multi-porous structure. The NPC is prepared using a facile and scalable MgO template method as-mediated by a magnesium nitrate-glycine solution combustion synthesis (SCS), in which the preparation conditions of calcination temperature and glycine-nitrate ratio are carefully studied. The NPC shows a high specific surface area up to 1958 m(2) g(-1) and contains hierarchical multi-pores of interconnected macro-, meso-and micro-pores. When applied as ORR electrocatalyst, the NPC-n2-1000 sample shows the highest activity, good durability and high tolerance against methanol, which is among the best reported carbon-base catalysts. The NPC samples also shows great potential as the active electrode material for supercapacitors. NPC-n2-900 sample exhibits a high specific capacitance of 232 F g(-1) at 1 A g(-1) in 6 M KOH electrolyte, a superior rate capability (205 F g(-1) at 10 A g(-1)) and a good cycling performance. The present work demonstrates that the combination of glycine-nitrate SCS and template introduction in one-step can turn the carbohydrate fuel to advanced porous carbon with prospective applications in high-performance energy storage devices.
• Starch-Derived Hierarchical Porous Carbon with Controlled Porosity for High Performance Supercapacitors

  Jinhui Cao, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  ACS Sustainable Chemistry & Engineering 6 6 7292 - 7303 2018年06月04日 [査読有り][通常論文]
   

  The development of green and clean synthetic techniques to produce carbon materials for energy storage and conversion applications has motivated researchers to use sustainable biomass. In this study, hierarchical porous carbon (HPC) with very high specific surface area and controlled porosity is synthesized by a novel and facile method, which employs an exothermic pyrolysis process of starch-magnesium nitrate raw materials with subsequent high temperature thermal treatment and acid washing. The biomass starch acts as both a reductant and carbon source, while magnesium nitrate is an oxidant and provides MgO template as pore creator. The vigorous exothermic pyrolysis of starch-magnesium nitrate mixture introduces MgO@C precursor with a highly 3D porous network containing meso- and macropores. After MgO template is removed, plenty of micro- and mesopores are further created. Experimental parameters including calcination temperature, starch-nitrate ratio, and magnesium salt species are comprehensively evaluated. The HPC shows a very large specific surface area up to about 2300 m2 g-1 and a hierarchical porous architecture composed of interconnected micro-, meso- and macropores. As an electrode material for supercapacitors, the HPC exhibits high specific capacitance (229 F g-1 at 1 A g-1 in a 6 M KOH electrolyte), good rate capability (211 F g-1 at even 10 A g-1) and outstanding cycling stability (94% capacitance retention after 10.000 cycles at 2 A g-1). The superior electrochemical performance of the HPC stems from both high surface area and the hierarchical multiporous structure, which provides an accessible pathway for electrolyte transport. These results demonstrate a very effective and low-cost method for scalable preparation of HPC using green biomass carbon source for supercapacitors, which also has potential applications such as adsorbent for water/gas treatment.
• 常温でも働く水素分離膜の開発

  青木芳尚

  クリーンエネルギー 27 6 44 - 51 2018年06月 [査読有り][招待有り]
  
• Electrochemical Oxidation of Hf–Nb Alloys as a Valuable Route to Prepare Mixed Oxides of Tailored Dielectric Properties

  A. Zaffora, F. D. Quarto, C. Kura, Y. Sato, Y. Aoki, H. Habazaki, M. Santamaria

  Adv. Electron. Mater. 4 5 1800006  2018年05月 [査読有り][通常論文]
   

  Metal oxides with high dielectric constant are extensively studied in the frame of substituting SiO2 as gate dielectric in nanoelectronic devices. Here, high-k mixed HfO2/Nb2O5 oxides are prepared by a facile electrochemical route starting from sputtering-deposited Hf-Nb alloys with several compositions. Transmission electron microscopy, grazing incidence X-ray diffraction, and glow discharge optical emission spectroscopy are employed to study the oxide structures, disclosing a crystalline-amorphous transition of the electrochemically prepared oxides by increasing the Nb content. Photo-electrochemical measurements allow the observation of optical transitions ascribed to localized states inside oxide bandgap induced by the presence of oxygen vacancies for Hf-rich oxides. Impedance measurements, coupled with withstand voltage and leakage current estimates, provide a comprehensive view of the real dielectric properties of the oxides. The highest epsilon is estimated for the anodic oxide grown on Hf-39 at% Nb (i.e., 45) but thin film grown on Hf-57 at% Nb alloy shows the best dielectric properties, revealing high dielectric constant, high withstand voltage, and low leakage current. Promising equivalent oxide thickness (down to 0.38 nm) is estimated for the oxide thin layers. The electrochemical oxidation represents a valuable and reliable way to prepare high-k thin oxide films with tailored and controlled dielectric properties.
• Strong Lanthanoid Substitution Effect on Electrocatalytic Activity of Double-Perovskite-Type BaLnMn2O5 (Ln = Y, Gd, Nd, and La) for Oxygen Reduction Reaction

  Etsushi Tsuji, Teruki Motohashi, Hiroyuki Noda, Yoshitaka Aoki, Hiroki Habazaki

  The Journal of Physical Chemistry C 122 13 7081 - 7087 2018年04月05日 [査読有り][通常論文]
   

  The oxygen reduction reaction (ORR) catalytic activity was systematically studied on the BaLnMn2O5 series (Ln = Y, Gd, Nd, and La) with a layered double-perovskite-type structure in an alkaline aqueous solution. The onset ORR potential and the number of electrons involved in ORR were found to be strongly Ln-dependent: both values were significantly higher for larger Ln = La and Nd than for smaller Ln = Gd and Y, despite similarities in their chemical compositions and crystal structures. The enhanced ORR activity of the Ln = La and Nd compounds is likely attributed to their stronger affinity to oxygen species, consistent with the greater oxygen storage capability of these compounds, as revealed by the water dissolution reaction at elevated temperatures.
• Front Cover: Ex Situ Evidence for the Role of a Fluoride‐Rich Layer Switching the Growth of Nanopores to Nanotubes: A Missing Piece of the Anodizing Puzzle (ChemElectroChem 4/2018)

  Khurram Shahzad, Damian Kowalski, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  ChemElectroChem 5 4 566 - 566 2018年02月16日
• Ex Situ Evidence for the Role of a Fluoride‐Rich Layer Switching the Growth of Nanopores to Nanotubes: A Missing Piece of the Anodizing Puzzle

  K. Shahzad, D. Kowalski, C. Zhu, Y. Aoki, H. Habazaki

  ChemElectroChem 5 4 570 - 570 2018年02月16日 [査読有り][通常論文]
   

  Anodizing involves a high-voltage electrochemical conversion process that forms barrier-type oxide layers or self-organized nanoporous/nanotubular structures. So far, Al2O3-like nanopores and TiO2-like nanotubes could be successfully synthesized on many metals and alloys. The proposed models of anodic oxide nanotubes growth, however, sacrifice from lack of evidence of the transition from nanopores to nanotubes. The present study demonstrates a missing piece of this anodizing puzzle, which is responsible for the formation of nanotubes in fluoride-containing organic electrolytes. For this purpose, we choose an anodic oxide formed on iron, as a model case, because both nanotubes and nanopores can be formed and slow kinetics of transition between those two forms allows us to observe, ex situ, a fluoride-rich-layer upon nanopores/nanotubes transition. The compositional fingerprints of this transition shed a light on the general mechanism of nanotubes growth in fluoride-containing electrolytes.
• High efficiency direct ammonia fuel cells based on BaZr0.1Ce0.8Y0.2O3-/Pd meta-oxide junction

  Y. Aoki, T. Yamaguchi, S. Kobayashi, D. Kowalski, C. Zhu, H. Habazak

  Global Challenge 2 2 1700088 - 1700088 2018年01月14日 [査読有り][通常論文]
   

  A direct ammonia-type intermediate temperature fuel cell is examined by means of a hydrogen membrane fuel cell (HMFC) comprising 1-mu m-thick BaZr0.1Ce0.7Y0.2O3-delta (BZCY) thin-film electrolyte and Pd solid anode. It generates the maximum power density of 0.58 W cm(-2) at 600 degrees C with ammonia fuels, and this value is found to be three times larger than the champion data of the recently reported direct ammonia-type proton-conducting ceramic fuel cells (PCFCs). AC impedance spectroscopy is performed to determine the interfacial polarization resistances, disclosing that the anodic overpotentials of HMFCs are at least one order of magnitude smaller than those of anode-supported PCFC under relatively high DC outputs. The anode reactions are driven by the oxidation of monoatomic hydrogen dissolving at the BZCY/Pd solid-solid interface, mediated via proton transfer from Pd to BZCY. The electrochemical analysis reveals that the BZCY/Pd junction forms Ohmic contact without growth of wide depletion layer and thus facilitates the proton transfer reactions because the interfacial region beneath Pd electrode can accommodate amounts of protonic defects as well as the bulk of BZCY due to the small depletion of holes under hole-proton thermodynamic equilibrium.
• Analysis of the Anode Reaction of Solid Oxide Electrolyzer Cells with BaZr0.4Ce0.4Y0.2O3-δElectrolytes and Sm0.5Sr0.5CoO3-δAnodes

  Taisei Kobayashi, Kosuke Kuroda, SeongWoo Jeong, Hyuna Kwon, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Journal of The Electrochemical Society 165 5 F342 - F349 2018年 [査読有り][通常論文]
   

  Anodic reaction pathways in proton-conducting solid oxide electrolyzer cells (H+−SOECs) were investigated using electrochemical impedance spectroscopy with a cell structure of Sm0.5Sr0.5CoO3 (anode) | BaZr0.4Ce0.4Y0.2O3-δ | Pt (cathode). Densely sintered BaZr0.4Ce0.4Y0.2O3-δ ceramics (> 97% relative density) were fabricated by a reactive sintering process with a 2 mol% Zn(NO3)2 additive and were applied as the electrolyte. The impedance spectra were measured while the oxygen (pO2) and water partial pressures (pH2O) in the anode side were systematically varied, which revealed that the SOECs have two polarization resistances at the anode side, one proportional to pO2 −1/4 and pH2O 0 and another insensitive to pO2 and pH2O. A comparison between the experimental results and elementary step modeling revealed that the actual anode reactions could be described by the reverse mode H+-SOFC cathode reactions, and, thus, the elementary steps dominating the anodic polarization resistance were assigned.
• Evaluation of thin film fuel cells with Zr-rich BaZrxCe0.8−xY0.2O3−δ electrolytes (x ≥ 0.4) fabricated by a single-step reactive sintering method

  Seongwoo Jeong, Taisei Kobayashi, Kosuke Kuroda, Hyuna Kwon, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  RSC Advances 8 46 26309 - 26317 2018年 [査読有り][通常論文]
   

  This paper reports a survey of power generation characteristics of anode-supported thin film fuel cells with Zr-rich BaZrxCe0.8-xY0.2O3-delta (x = 0.4, 0.6, 0.7, and 0.8) proton-conducting electrolytes, which were fabricated by single step co-firing with Zn(NO3)(2) additives at a relatively low temperature (1400 degrees C). The grain sizes significantly increased to several mu m for x = 0.4 and 0.6, whereas the grain sizes remained in the sub-mu m ranges for x = 0.7 and 0.8, which resulted in large gaps of the fuel cell performances at x over and below 0.6. The cells for x = 0.4 and 0.6 exhibited efficient power generation, yielding peak powers of 279 and 336 mW cm(-2) at 600 degrees C, respectively, which were higher than those of the corresponding cells previously reported. However, the performances abruptly deteriorated with the increasing x to more than 0.7 because the electrolyte films were highly resistive due to the coarse-grained microstructures. Impedance spectroscopy for the dense sintered BaZrxCe0.8-xY0.2O3-delta discs confirmed that the total proton conductivity of BaZr0.6Ce0.2Y0.2O3-delta was higher than that of BaZr0.4Ce0.4Y0.2O3-delta at temperatures above 500 degrees C despite relatively small grain sizes. In addition, BaZr0.6Ce0.2Y0.2O3-delta cells could gain a stable current throughout a continuous run for a few days under CO2-containing fuel supply, which was due to high fraction of thermodynamically stable BaZrO3 matrices. It was demonstrated that BaZr0.6Ce0.2Y0.2O3-delta is a promising electrolyte for proton-conducting ceramic fuel cells with excellent proton conductivity and CO2 tolerance at intermediate temperatures.
• Diffusion-controlled growth of TiO2 mesoporous anodic films in hot phosphate/glycerol electrolytes

  Etsushi Tsuji, Shiki Matsuura, Yoshitaka Aoki, Hiroki Habazaki

  Electrochemistry 86 4 184 - 189 2018年01月01日 [査読無し][通常論文]
   

  © The Electrochemical Society of Japan, All rights reserved. This paper reports unusual diffusion-controlled growth of TiO2 mesoporous anodic films on titanium in hot phosphate/glycerol electrolytes. The formation behavior was investigated by cyclic voltammetry (CV) between 0 and 5 V vs. Pt at 433 K. The current density became almost constant above 1.5 V vs. Pt during the positive potential sweep, and was maintained even during the negative potential sweep. This is contrast to a drastic decrease in current density in changing the direction of potential sweep from the positive to negative in fluoride-containing ethylene glycol electrolyte. The constant current density between 1.5 and 5 V vs. Pt increased with an increase in the basicity of the hot phosphate electrolyte, suggesting that the rate-determining step of the film formation in the hot phosphate electrolyte was diffusion process of oxygen sources in the electrolyte, not the ion migration in the thin barrier layer under the high electric field. When CV measurements were conducted to higher potentials up to 20 V vs. Pt, anatase was developed above 7 V vs. Pt, leading to generate oxygen gas. The film morphology was also potential-dependent and the diffusion current was also influenced by the film morphology as well as oxygen gas generation.
• Enhanced hydrogen permeability of hafnium nitride nanocrystalline membranes by interfacial hydride conduction

  Chiharu Kura, Sho Fujimoto, Yuji Kunisada, Damian Kowalski, Etsushi Tsuji, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Journal of Materials Chemistry A 6 6 2730 - 2741 2018年 [査読有り][通常論文]
   

  Hydrogen permeability based on mixed hydride ion electron conduction was demonstrated for hafnium nitride HfNx (film thickness of 100-500 nm, x = 0.8 and 1.0) nanocrystalline membranes. Nanocrystalline films with a (100) orientation and crystallite sizes of a few tens of nanometers were prepared on porous alumina supports by radio frequency (RF) reactive sputtering. Combined spectroscopic, permeability, and microbalance analysis suggests that the nanocrystalline matrices were readily hydrogenated by the formation of Hf-H terminal groups on the internal grain surfaces at ambient temperature and thus efficient hydrogen permeation took place due to an enhanced diffusion of hydridic defects through the grain boundaries this was further aided by the Hf-H bond exchange process. Hence, membranes with an average crystallite size of 11 nm yielded a hydrogen flux of 6 × 10-7 mol cm-2 s-1 at 25 °C at an applied hydrogen partial pressure of 50 kPa this value is higher than those exhibited by the current state-of-the-art Pd membranes. These findings establish a new concept for Pd alternatives based on the pronounced hydric conductivity of transition metal nitride nanomaterials.
• Anode reaction analysis of solid oxide electrolyzer cells at BaZr0.4Ce0.4Y0.2O3-/Sm0.5Sr0.5CoO3- interfaces

  T. Kobayashi, K. Kuroda, S. W. Jeong, H. Kwon, C. Zhu, H. Habazaki, Y. Aoki

  Journal of the Electrochemical Society 165 5 F342 - F349 2018年 [査読有り][通常論文]
  
• Rapid and Repeatable Self‐Healing Superoleophobic Porous Aluminum Surface Using Infiltrated Liquid Healing Agent

  K. Nakayama, A. Koyama, C. Zhu, Y. Aoki, H. Habazaki

  Adv. Mater. Interface 5 19 1800566  2018年 [査読有り][通常論文]
   

  This paper reports rapid self-healing on superoleophobic hierarchically porous aluminum surfaces within 1 h even at room temperature. This self-healing surface is prepared by infiltration of a liquid fluoroalkylsilane (FAS) coating into the substrate pores. The FAS-infiltrated dual-pore superoleophobic surface becomes superoleophilic after oxygen plasma treatment due to the damage done to the organic coating. However, the superoleophobicity is completely recovered by exposure to normal atmosphere at room temperature, and this rapid self-healing is repeatable. The FAS liquid appears to coat the nanopore walls, rather than filling the nanopores. The high wettability of FAS on surfaces induces the rapid recoating of the plasma-damaged surface, contributing to the self-healing of the superoleophobicity.
• Highly increased breakdown potential of anodic films on aluminum using a sealed porous layer

  J.H. Cao, Y. Sato, D. Kowalski, C. Zhu, Y. Aoki, H.Habazaki

  J. Solid State Electrochem. 22 7 2073 - 2081 2018年 [査読有り][通常論文]
   

  The growth of a uniform barrier-type anodic film on aluminum is usually terminated by electric breakdown, which is controlled by the resistance of electrolyte or anion concentration. In this study, highly resistive porous layers have been introduced by anodizing aluminum in sulfuric acid electrolyte followed by boiling water treatment to examine their influence on the electric breakdown potential. The pores of the porous alumina film are sealed by forming hydrated alumina (pseudo-boehmite) after the boiling water treatment. The breakdown potential increases to over 1500 V for the pore-sealed aluminum specimens on anodizing in sodium tungstate electrolyte. The electrochemical impedance spectroscopy measurements revealed an increased resistance of the porous layer after the pore-sealing treatment. GDOES depth profile analysis disclosed that the sealed porous layer impedes the incorporation of tungsten species into the barrier layer. The introduction of a highly resistive layer that also suppresses the anion incorporation on aluminum is effective in increasing the breakdown potential of anodic films.
• Evaluation of thin film fuel cells with Zr-rich side BaZrxCe0.8-xY0.2O3- electrolytes fabricated by single step cofiring process

  S. W. Jeong, T. Kobayashi, K. Kuroda, H. Kwon, C. Zhu, H. Habazaki, Y. Aoki

  RSC Advances 8 7 26309 - 26317 2018年 [査読有り][通常論文]
   

  This paper reports a survey of power generation characteristics of anode-supported thin film fuel cells with Zr-rich BaZrxCe0.8-xY0.2O3-delta (x = 0.4, 0.6, 0.7, and 0.8) proton-conducting electrolytes, which were fabricated by single step co-firing with Zn(NO3)(2) additives at a relatively low temperature (1400 degrees C). The grain sizes significantly increased to several mu m for x = 0.4 and 0.6, whereas the grain sizes remained in the sub-mu m ranges for x = 0.7 and 0.8, which resulted in large gaps of the fuel cell performances at x over and below 0.6. The cells for x = 0.4 and 0.6 exhibited efficient power generation, yielding peak powers of 279 and 336 mW cm(-2) at 600 degrees C, respectively, which were higher than those of the corresponding cells previously reported. However, the performances abruptly deteriorated with the increasing x to more than 0.7 because the electrolyte films were highly resistive due to the coarse-grained microstructures. Impedance spectroscopy for the dense sintered BaZrxCe0.8-xY0.2O3-delta discs confirmed that the total proton conductivity of BaZr0.6Ce0.2Y0.2O3-delta was higher than that of BaZr0.4Ce0.4Y0.2O3-delta at temperatures above 500 degrees C despite relatively small grain sizes. In addition, BaZr0.6Ce0.2Y0.2O3-delta cells could gain a stable current throughout a continuous run for a few days under CO2-containing fuel supply, which was due to high fraction of thermodynamically stable BaZrO3 matrices. It was demonstrated that BaZr0.6Ce0.2Y0.2O3-delta is a promising electrolyte for proton-conducting ceramic fuel cells with excellent proton conductivity and CO2 tolerance at intermediate temperatures.
• Enhanced hydrogen permeability of hafnium nitride nanocrystalline membranes by interfacial hydride conduction

  Chiharu Kura, Sho Fujimoto, Yuji Kunisada, Damian Kowalski, Etsushi Tsuji, Chunyu Zhu, Hiroki Habazaki, Yoshitaka Aoki

  Journal of Materials Chemistry A 6 6 2730 - 2741 2018年 [査読有り][通常論文]
   

  Hydrogen permeability based on mixed hydride ion electron conduction was demonstrated for hafnium nitride HfNx (film thickness of 100-500 nm, x = 0.8 and 1.0) nanocrystalline membranes. Nanocrystalline films with a (100) orientation and crystallite sizes of a few tens of nanometers were prepared on porous alumina supports by radio frequency (RF) reactive sputtering. Combined spectroscopic, permeability, and microbalance analysis suggests that the nanocrystalline matrices were readily hydrogenated by the formation of Hf-H terminal groups on the internal grain surfaces at ambient temperature and thus efficient hydrogen permeation took place due to an enhanced diffusion of hydridic defects through the grain boundaries this was further aided by the Hf-H bond exchange process. Hence, membranes with an average crystallite size of 11 nm yielded a hydrogen flux of 6 × 10-7 mol cm-2 s-1 at 25 °C at an applied hydrogen partial pressure of 50 kPa this value is higher than those exhibited by the current state-of-the-art Pd membranes. These findings establish a new concept for Pd alternatives based on the pronounced hydric conductivity of transition metal nitride nanomaterials.
• 窒化チタン微結晶膜におけるヒドリドイオン伝導の発現とそれによる常温水素膜分離

  青木芳尚

  真空技術協会誌 132 32 - 41 2017年12月 [査読有り][招待有り]
  
• Co9S8 Nanoparticles Incorporated in Hierarchically Porous 3D Few-Layer Graphene-Like Carbon with S,N-Doping as Superior Electrocatalyst for Oxygen Reduction Reaction

  Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki

  PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION 34 11 1700296/1 - 1700296/7 2017年11月 [査読有り][通常論文]
   

  Electrochemical oxygen reduction reaction (ORR), using nonprecious metal catalysts, has attracted great attention due to the importance in renewable energy technologies, such as fuel cells and metal-air batteries. A simple and scalable synthetic route is demonstrated for the preparation of a novel 3D hybrid nanocatalyst consisting of Co9S8 nanoparticles which are incorporated in N, S-doped carbon (N, S-C) with rational structure design. In particular, the hybrid catalyst is prepared by direct pyrolysis and calcination of a gel mixture of Mg, Co nitrate-thiourea-glycine under Ar atmosphere, with subsequent HCl washing. The properties of obtained hybrid catalyst are quite dependent on calcination temperature and added glycine amount. Under a molar ratio of Co5-Mg15-tu10-gl45 and a calcination temperature of 900 degrees C, Co9S8 nanoparticles are embedded in a well-developed carbon matrix which shows a porous 3D few-layer graphene-like N, S-C with open and hierarchical micro-meso-macro pore structure. Because of the synergistic effect between Co9S8 nanoparticles and well-developed carbon support, the composite exhibits high ORR activity close to that of commercial Pt/C catalyst. More importantly, the composite displays superior long-term stability and good tolerance against methanol. The strategy developed here provides a novel and efficient approach to prepare a cost-effective and highly active ORR electrocatalyst.
• Facile preparation of self-healing superhydrophobic CeO2 surface by electrochemical processes

  Katsutoshi Nakayama, Takuya Hiraga, Chunyu Zhu, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  APPLIED SURFACE SCIENCE 423 968 - 976 2017年11月 [査読有り][通常論文]
   

  Herein we report simple electrochemical processes to fabricate a self-healing superhydrophobic CeO2 coating on Type 304 stainless steel. The CeO2 surface anodically deposited on flat stainless steel surface is hydrophilic, although high temperature-sintered and sputter-deposited CeO2 surface was reported to be hydrophobic. The anodically deposited hydrophilic CeO2 surface is transformed to hydrophobic during air exposure. Specific accumulation of contaminant hydrocarbon on the CeO2 surface is responsible for the transformation to hydrophobic state. The deposition of CeO2 on hierarchically rough stainless steel surface produces superhydrophobic CeO2 surface, which also shows self-healing ability; the surface changes to superhydrophilic after oxygen plasma treatment but superhydrophobic state is recovered repeatedly by air exposure. This work provides a facile method for preparing a self-healing superhydrophobic surface using practical electrochemical processes. (C) 2017 Elsevier B.V. All rights reserved.
• Nitrogen‐Doped Hierarchical Porous Carbon Architecture Incorporated with Cobalt Nanoparticles and Carbon Nanotubes as Efficient Electrocatalyst for Oxygen Reduction Reaction

  C. Zhu, C. Kim, Y. Aoki, H. Habazaki

  Advanced Materials Interfaces 4 19 1700583/1 - 1700583/8 2017年10月 [査読有り][通常論文]
   

  Hierarchical porous carbon has attracted great interest because of its distinctive structure and superior properties for designing electrochemical energy storage and conversion devices. In this work, a novel method to fabricate nitrogen-doped hierarchical porous carbon (NHPC) is reported, which is incorporated with Co nanoparticles and carbon nanotubes (CNTs). The NHPC is prepared using a facile and scalable MgO-Co template method. Metal nitrate-glycine solution combustion synthesis, followed by a high temperature calcination, is used to prepare MgO-Co/N-doped carbon precursor. CNTs are formed by the in situ Co-catalytic growth during heat treatment; at the same time, localized graphitic layers are also formed around the Co nanoparticles. After acid washing, NHPC with hierarchical multipores and ultrafine Co nanoparticles is obtained. When applied as oxygen reduction reaction (ORR) catalyst, the NHPC displays high catalytic activity not only in terms of onset potential and current density, but also superior durability and tolerance to methanol crossover in alkaline electrolyte. The remarkable ORR activity is originated from the cooperative effects of high specific surface area, hierarchical pore structure, ultrasmall Co nanocrystals, localized graphitic layers, CNTs, and N-doping.
• Highly increased capacitance and thermal stability of anodic oxide films on oxygen-incorporated Zr-Ti alloy

  H. Habazaki, K. Kobayashi, E. Tsuji, C. Zhu, Y. Aoki, S. Nagata

  JOURNAL OF SOLID STATE ELECTROCHEMISTRY 21 10 2807 - 2816 2017年10月 [査読有り][通常論文]
   

  Heat treatment of Zr-24 at% Ti alloy with barrier-type dielectric anodic oxide films was conducted at 473 K in air to examine the thermal stability of the dielectric oxide films for possible electrolytic capacitor application. The anodic oxide film was formed by anodizing of the alloy at 50 V for 30 min in 0.1 mol dm(-3) ammonium pentaborate electrolyte. The anodic oxide film of 125 nm thickness was crystalline, containing both monoclinic and tetragonal ZrO2 phase. It was found that marked thickening of the oxide film with generation of cracks occurred during heat treatment at 473 K. Thus, the dielectric loss was largely increased along with the capacitance increase. In contrast, the anodic oxide film formed on the oxygen-incorporated alloy remained uniform, and no significant increase in dielectric loss was observed even after the heat treatment. The capacitance of the anodic film became as high as 4.8 mF m(-2), which was nearly twice that on Ta. The high capacitance was associated with the preferential formation of tetragonal ZrO2 phase in the anodic oxide film on the oxygen-incorporated alloy. Findings indicated that the oxygen-incorporated Zr-Ti alloy is a promising novel material for capacitor application.
• Hydrogen separation by nanocrystalline titanium nitride membranes with high hydride ion conductivity

  Chiharu Kura, Yuji Kunisada, Etsushi Tsuji, Chunyu Zhu, Hiroki Habazaki, Shinji Nagata, Michael P. Mueller, Roger A. De Souza, Yoshitaka Aoki

  NATURE ENERGY 2 10 786 - 794 2017年10月 [査読有り][通常論文]
   

  The production of pure hydrogen for use in energy applications and related industries often relies on the permeation of hydrogen through palladium-based membranes. However, the scarcity of Pd reserves necessitates the development of affordable alternatives with high hydrogen permeability. Here we report room-temperature hydrogen permeability of titanium nitrides (widely used as tough and inert coating materials) enabled by mixed hydride ion-electron conductivity. Combined spectroscopic, permeability and microgravimetric measurements reveal that nanocrystalline TiNx membranes feature enhanced grain-boundary diffusion of hydride anions associated with interfacial Ti cations on nanograins. Since the corresponding activation energies are very low (<10kJmol(-1)), these membranes yield a considerably higher room-temperature hydrogen flux than Pd membranes of equivalent thickness. Overall, the current study establishes general guidelines for developing hydride ion transport membranes based on a simple transition metal nitride for hydrogen purification, membrane reactors and other applications.
• Low temperature oxygen storages of CrIV-CrV mixed valence YCr1-xPxO4- driven by local condensation around oxygen-deficient orthochromit

  Y. Aoki, K. Kuroda, S. Hinokuma, C. Kura, C. Zhu, E. Tsuji, A. Nakao, M. Wakeshima, Y. Hinatsu, H. Habazaki

  Journal of the American Chemical Society 139 32 11197 - 11206 2017年08月 [査読有り][通常論文]
   

  The oxygen storage capability and related defect structure of tetrahedral orthochromite(V) compound YCr1-xPxO4 (x = 0, 0.3, 0.5, and 0.7) were investigated by employing thermal gravimetry and in situ X-ray spectroscopy for reversible oxygen store/release driven by healing-cooling cycles in the temperature range from 50 to 600 degrees C. YCr1-xPxO4 started releasing oxygen as heated from 50 degrees C under ambient atmosphere, with reduction of Cr-V to Cr-IV, while the reduced YCr1-xPxO4-delta phase was significantly reoxidized via absorbing oxygen by cooling to 50 degrees C under ambient atmosphere, recovering the original stoichiometric phase. Operando X-ray adsorption spectroscopy and first-principles calculations demonstrate that nonstoichiometric YCr1-xPxO4-delta phases were stabilized by forming linking polyhedral (Cr2O76-)-O-IV via corner sharing between oxygen-deficient (CrO32-)-O-IV and adjacent (CrO44-)-O-IV. YCr1-xPxO4 was found to have an extremely low reduction enthalpy of about 20 kJ mol(-1) probably due to the relatively high reduction potential of high-valence-state Cr(V)/Cr(IV) redox pairs, thereby resulting in reversible oxygen storage in such a low-temperature region.
• Brownmillerite-type Ca2FeCoO5 as a Practicable Oxygen Evolution Reaction Catalyst

  Etsushi Tsuji, Teruki Motohashi, Hiroyuki Noda, Damian Kowalski, Yoshitaka Aoki, Hajime Tanida, Junji Niikura, Yukinori Koyama, Masahiro Mori, Hajime Arai, Tsutomu Ioroi, Naoko Fujiwara, Yoshiharu Uchimoto, Zempachi Ogumi, Hiroki Habazaki

  CHEMSUSCHEM 10 14 2864 - 2868 2017年07月 [査読有り][通常論文]
   

  Here, we report remarkable oxygen evolution reaction (OER) catalytic activity of brownmillerite (BM)-type Ca2FeCoO5. The OER activity of this oxide is comparable to or beyond those of the state-of-the-art perovskite (PV)-catalyst Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and a precious-metal catalyst RuO2, emphasizing the importance of the characteristic BM structure with multiple coordination environments of transition metal (TM) species. Also, Ca2FeCoO5 is clearly advantageous in terms of expense/laboriousness of the material synthesis. These facts make this oxide a promising OER catalyst used in many energy conversion technologies such as metal-air secondary batteries and hydrogen production from electrochemical/photocatalytic water splitting.
• High efficiency direct ammonia type fuel cells based on BaZrxCe0.8-xY0.2O3/Pd oxide-metal junctions

  Y. Aoki, T. Yamaguchi, S. Kobayashi, C. Zhu, H. Habazaki

  ECS Transactions 78 1 1511 - 1515 2017年05月30日 [査読有り][通常論文]
   

  Hydrogen membrane fuel cells, HMFC, were fabricated by RF sputtering deposition of BaZr0.1Ce0.7Y0.2O3-δ thin films on Pd solid anode. The HMFC can give OCV of 1.0 V and peak power density of 0.8 W cm-2 at 600°C by using H2 fuels. The direct NH3 fueled HMFC reveals OCV of 0.92 V and peak power density of 0.58 W cm-2 at 600°C. These performances are superior to the best data of direct ammonia PCFC.
• A facile one-pot synthesis of FeOx/carbon/graphene composites as superior anode materials for lithium-ion batteries

  Cheng-Gong Han, Chunyu Zhu, Nan Sheng, Yoshitaka Aoki, Hiroki Habazaki, Tomohiro Akiyama

  ELECTROCHIMICA ACTA 235 88 - 97 2017年05月 [査読有り][通常論文]
   

  Iron oxide has been considered as one of the most promising anode materials due to its high theoretical capacity, low cost and environmental friendliness. However, few simple and effective method is explored for preparing iron oxides with high electrochemical performance via alleviating the volume change and agglomeration of active particles. In this work, FeOx/carbon/graphene composites are fabricated by a facile solution combustion synthesis within several minutes in one step. Characterization demonstrates that FeOx nanoparticles are well-dispersed in the graphene matrix. The presence of graphene effectively alleviates the agglomeration of FeOx nanoparticles, and accommodates the volume changes during the cycling process, thereby resulting in the excellent electrochemical performance. FeOx/carbon/graphene (31.4 wt.% graphene) delivers a higher discharge capacity of 824 mAh g (1) after 100 cycles at 0.4 A g (1), in comparison to the value of 301 mAh g (1) for the composite without graphene. This easily prepared FeOx/carbon/graphene composite with excellent electrochemical performance can be considered as one promising anode material used for lithium-ion batteries. (C) 2017 Elsevier Ltd. All rights reserved.
• 金属/酸化物ヘテロ接合からなる中温作動燃料電池の分極挙動」，「環境・エネルギーに関わるセラミックスの界面設計

  青木芳尚

  セラミックス協会誌 52 2 82 - 86 日本セラミックス協会 2017年02月 [査読有り][招待有り]
  
• Formation of Nanoporous NiFe2O4 Oxide Films by Anodizing of Fe-Ni Alloy

  R. Tomizawa, C. Zhu, E. Tsuji, Y. Aoki, H. Habazaki

  OXIDE FILMS: A SYMPOSIUM IN HONOR OF MASAHIRO SEO 75 27 67 - 75 2017年 [査読有り][通常論文]
   

  In this study, a nanoporous anodic film was successfully formed on Fe-41 mass% Ni alloy at a constant voltage of 40 V in ethylene glycol electrolyte containing 0.1 mol dm-(3) NH4F and 0.5 mol dm(-3) H2O. The resultant anodic film contained fluoride species and was rather soluble even in de-ionized water. The heat treatment in an argon atmosphere at and above 673 K converted a poorly crystalline anodic film to a crystalline film with a (FeNi)(3)O-4 spinel phase with the nanoporous morphology remaining unchanged. The activity of the heattreated specimens for oxygen evolution reaction (OER) was examined and the results were compared with the anodized iron specimens after heat treatment. The Fe-Ni alloy specimen heattreated at optimized temperature showed the improved activity in comparison with the corresponding iron specimen. Anodizing is promising to form a highly porous electrode directly on metal substrate.
• MnO/NC anode materials for lithium-ion batteries prepared by cotton-templated combustion synthesis

  C. G. Han, C. Zhu, Y. Aoki, H. Habazaki, T. Akiyama

  Green Energy & Environment 2 4 377 - 386 2017年 [査読有り][通常論文]
   

  We herein report a facile one-pot synthesis of MnO/N-doped carbon (N-C) composites via a sustainable cotton-template glycine-nitrate combustion synthesis to yield superior anode materials for Li+ ion batteries. MnO nanoparticles with several nanometers were well-embedded in a porous N-doped carbon matrix. It displays the unique characteristics, including the shortened Lition transport path, increased contact areas with the electrolyte solution, inhibited volume changes and agglomeration of nanoparticles, as well as good conductivity and structural stability during the cycling process, thereby benefiting the superior cycling performance and rate capability. This favorable electrochemical performance of obtained MnO/N-C composites via a one-pot biomass-templated glycine/nitrate combustion synthesis renders the suitability as anode materials for Li-ion batteries. (C) 2017, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.
• Anodic films obtained on Ti6Al4V in aluminate solutions by spark anodizing: Effect of OH- and WO4-2 additions on the tribological properties

  D. Quintero, M. A. Gomez, J. G. Castano, E. Tsuji, Y. Aoki, F. Echeverria, H. Habazaki

  SURFACE & COATINGS TECHNOLOGY 310 180 - 189 2017年01月 [査読有り][通常論文]
   

  Spark anodizing of Ti6A14V alloy has been performed in alkaline electrolytes containing aluminate to form wear resistant coatings. Coatings obtained under potentiostatic conditions exhibit a better wear resistance, with a wear rate approx. 10 times lower than galvanostatic coatings, due to the formation of coatings with low porosity since potentiostatic mode controls the size of the micro-discharges. The coatings consist mainly of gamma-Al2O3, whilst Al2TiO5 is present in minor proportions. For some coatings, the formation of Al6KO5,5 is observed due to the incorporation of potassium into the coating. EDS analysis shows that aluminum is the main constituent of the coatings, being mainly incorporated from the anodizing solution and homogeneously distributed into the coating. A decrease in pore density between 15 and 30% and roughness reduction of 10 to 60% was obtained with KOH and Na2WO4 additions, improving the coating wear resistance in pin-on-disc wear tests, especially by Na2WO4 addition. (C) 2016 Elsevier B.V. All rights reserved.
• High-efficiency hydrogen membrane fuel cells with BaCe0.8Y0.2O3- electrolyte thin films and Pd1-xAgx solid anode

  Y. Aoki, T. Yamaguchi, E. Tsuji, H. Habazaki

  Journal of the Electrochemical Society 164 6 F577 - F581 2017年 [査読有り][通常論文]
   

  Fuel cell performances at intermediate temperature 600 degrees C were examined for the hydrogen membrane fuel cell (HMFC) designed by rf sputter deposition of a BaCe0.8Y0.2O3-delta thin film electrolyte (1 mu m thickness) on a Pd1-xAgx (x = 0, 0.2 and 0.4) solid anode. The maximum power density reached to 1.2 W cm(-2) at 600 degrees C with the Pd0.8Ag0.2 anodes, and this value was much higher than the champion data of the recent anode-supported proton-conducting ceramic fuel cells (PCFCs). By electrochemical impedance analysis, it was demonstrated that the hydrogen permeability was crucial to the anode polarization losses of the HMFC because the charge transfer resistances and concentration overpotentials at BaCe0.8Y0.2O3-delta/Pd oxide-metal interfaces are simultaneously improved with the alloys having higher hydrogen permeability. (C) 2017 The Electrochemical Society. All rights reserved.
• Electrochemical impedance analysis of high efficiency hydrogen membrane fuel cells based on sputter deposited BaCe0.8Y0.2O3- thin films

  Y. Aoki, S. Kobayashi, T. Yamaguchi, E. Tsuji, H. Habazaki, K. Yashiro, T. Kawada, T. Ohtsuka

  The Journal of Physical Chemistry C 120 29 15976 - 15985 2016年07月 [査読有り][通常論文]
   

  A hydrogen membrane fuel cell (HMFC) consisting of a Pd solid anode, 1 mu m thick BaCe0.8Y0.2O3-delta thin-film electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3 cathode was examined. A single-phase BaCe0.8Y0.2O3-delta thin film was successfully deposited by radio frequency cosputtering with BaCe0.8Y0.2O3 and Ce0.9Y0.1O2 double targets, as checked by X-ray diffraction, transmission electron microscopy, and wavelength dispersive X-ray analysis. The maximum power density reached 1.05 W cm-(2) at 600 degrees C, and this value was higher than the champion data of the recently reported proton-conducting ceramic fuel cells (PCFCs). Electrochemical impedance analysis was performed to characterize the anode and cathode polarization behavior. The impedance responses of HMFC were explicable with an equivalent circuit built by a series connection of cathode charge-transfer elements and anode mass-transfer elements. The contribution of the mass transfer in Pd bulk was found to be relatively small in comparison to cathode polarization and ohmic loss in normal fuel cell atmosphere. Moreover, the cathodic charge-transfer resistance of HMFC was found to be 25 times smaller than those of the recent PCFC systems. The current results demonstrated that the HMFC retained relatively large gas-proton-electron triple-boundary zones near the interface between the BaCe0.8Y0.2O3-delta electrolyte and porous La0.6Sr0.4Co0.2Fe0.8O3-delta cathode.
• Control of Surface Wettability of Aluminum Mesh with Hierarchical Surface Morphology by Monolayer Coating: From Superoleophobic to Superhydrophilic

  Katsutoshi Nakayama, Etsushi Tsuji, Yoshitaka Aoki, Soo-Gil Park, Hiroki Habazaki

  JOURNAL OF PHYSICAL CHEMISTRY C 120 29 15684 - 15690 2016年07月 [査読有り][通常論文]
   

  This paper reports the formation of hierarchically structured aluminum mesh by a combination of simple chemical etching and anodizing. The former introduced micrometer-sized etch pits, and the latter produced nanopores of the order of 10 nm on the mesh with 150 mu m mesh openings. Coating the mesh with a monolayer of fluoroalkyl phosphate made the surface superoleophobic to practically any liquid, including hexane with a surface tension as low as 18.4 mN m(-1). The hierarchical triple similar to 100 mu m/similar to 1 mu m/similar to 10 nm pore surface morphology improved the superoleophobicity compared to the dual similar to 100 mu m/similar to 10 nm and similar to 1 mu m/similar to 10 nm pore structures. When the aluminum mesh was coated with a fluorine-free alkylphosphate monolayer, the surface was superhydrophobic, but superoleophilic. The noncoated aluminum mesh was superhydrophilic and superoleophilic with a liquid contact angle close to 0 degrees. Using the aluminum mesh with an alkylphosphate coating, a water/oil mixture was successfully separated by allowing only the oil to pass through the mesh. In addition, the mixture was separated using noncoated mesh wetted with water, since oil was not able to pass through the mesh in this case.
• Characterization of Corrosion-resistant, Nanometer-thick, Layer-by-layer Aluminosilicate Coatings Prepared on Stainless Steel

  H. Habazaki, T. Kimura, Y. Aoki, E. Tsuji, T. Yano, K. Shimizu, A. W. Hassel

  ELECTROCHIMICA ACTA 201 311 - 319 2016年05月 [査読有り][通常論文]
   

  Highly corrosion-resistant, similar to 65-nm-thick, layer-by-layer aluminosilicate coatings have been prepared by multiple spin casting on Type 430 stainless steel. These coatings have been characterized by field emission scanning electron microscopy, transmission electron microscopy, conductive atomic force microscopy, and micro-electrochemical measurements using a microcapillary cell. The coatings annealed at 400 degrees C are non-uniform and contain fine iron oxide nodules, which are formed in high densities on the {111} grain surface of the steel. The iron oxide nodules arise from the outward diffusion of the oxidized iron from the substrate through the coating. The coatings annealed at 400 degrees C are more insulating compared with those before annealing; however, the nodule sites are less insulating owing to the development of more conductive iron oxide channels in the coatings. A microcapillary cell study reveals that the coated specimens prepared from diluted precursor solutions by a layer-by-layer process exhibit higher pitting potential in 3.5 wt% NaCl solution compared with those prepared through a single-layer process. Moreover, the coated specimen obtained from the layer-by-layer process exhibits similarly high pitting potential even at the flaw sites in the coating; in contrast, the pitting potential in the flaw-containing regions of the coated specimen obtained from a single-layer process shifts towards the less noble direction. The layer-by-layer coating is also effective in suppressing the corrosion of the scratched region of the coated specimens, owing possibly to the excellent adhesion between the coating and the substrate. (C) 2015 Elsevier Ltd. All rights reserved.
• Redox-induced proton insertion and desertion of zircon-type neodymium chromate(V)

  Yoshitaka Aoki, Kosuke Kuroda, Etsushi Tsuji, Hiroki Habazaki

  Solid State Ionics 285 175 - 179 2016年02月01日 [査読有り][通常論文]
   

  Redox transformation of NdCrVO4 involved by insertion/desertion of protons was examined by XRD, XPS, in situ FT-IR and fuel cell tests. It was found that NdCrO4 caused bulk reduction with H2 gas at around 400 °C, changing to amorphous Nd(III)-Cr(III) hydroxide phase. This hydroxide phase, however, could recover to the original zircon type oxide phase by air oxidation at the same temperature region. Proton-conducting ceramic fuel cells having NdCrO4 film as an interlayer between cathode and electrolyte was fabricated and the cell was confirmed to exhibit remarkable power generation giving rise to OCV of more than 1.0 V at 500 °C. It was speculated that the interlayer facilitates proton transfer from electrolyte to cathode because redox cycling of NdCrO4 and the corresponding hydroxide was driven by the high proton chemical potential at the interface with electrolyte and plenty of oxygen in cathode gases.
• Formation of porous anodic films on carbon steels and their application to corrosion protection composite coatings formed with polypyrrole

  Yoshiki Konno, Ahmed A. Farag, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  Journal of the Electrochemical Society 163 7 C386 - C393 2016年 [査読有り][通常論文]
   

  The growth behavior of nanoporous anodic films on carbon steel containing 0.213 mass% carbon has been examined. The films were grown by anodizing in an ethylene glycol (EG) electrolyte containing 0.1 mol dm-3 NH4F and 0.5 mol dm-3 H2O. The steel contains carbide precipitates with sizes in the range 50-800 nm. The anodic film formed on the carbide phase grew more slowly and was more chemically soluble during anodizing, resulting in submicrometer pits on the anodic film. The nanoporous morphology of the anodic films formed on an á-Fe matrix resembled those formed on iron. Heat treatment of the anodized specimens caused transformation of the chemically soluble fluoride-containing amorphous or poorly crystalline anodic films to crystalline oxide films containing α-Fe2O3 and Fe3O4. Polypyrrole (PPy)was electropolymerized on the transformed surfaces to form a corrosion-protective composite coating. The resultant specimens coated with the composite coating showed improved durability compared to passivated steel with a PPy coating.
• Growth of barrier type anodic film on magnesium in ethylene glycol-water mixed electrolytes containing fluoride and phosphate

  Khurram Shahzad, Chunyu Zhu, Etsushi Tsuji, Yoshitaka Aoki, Shinji Nagata, Hiroki Habazaki

  Materials Transactions 57 9 1552 - 1559 2016年 [査読有り][通常論文]
   

  In this study, we report the formation of barrier-type anodic films on magnetron-sputtered magnesium films at a constant current density of 10 A m-2 in ethylene glycol (EG)-H2O electrolytes containing 0.1 mol dm-3 ammonium fluoride and 0.1 mol dm-3 dipotassium hydrogen phosphate. The growth efficiency is close to 100% up to 10 vol% H2O, but decreases to 52% in the EG-free aqueous electrolyte. Even at such a low efficiency in the aqueous electrolyte a uniform barrier-type anodic film with flat and parallel metal/film and film/electrolyte interfaces is developed over 100 V. This is contrast to the non-uniform film growth and low breakdown voltage in the phosphate-free aqueous electrolyte containing ammonium fluoride. The anodic films appear to be amorphous regardless of H2O concentration in the phosphate-containing electrolytes, and consist of phosphate-incorporated oxy fluoride. The phosphate incorporation is suppressed by an increase in H2O concentration. In addition, the anodic films consist of two layers with an inner layer containing less amount of phosphate. The outer layer is probably formed at the film/electrolyte interface by the migration of Mg2+ ions outwards, while the inner layer is formed at the metal/film interface. The film formation at the former interface even in the aqueous electrolyte at low efficiency is likely to contribute to the formation of barrier films, not porous anodic films.
• Fabrication of a resistive switching gallium oxide thin film with a tailored gallium valence state and oxygen deficiency by rf cosputtering process

  Chiharu Kura, Yoshitaka Aoki, Etsushi Tsuji, Hiroki Habazaki, Manfred Martin

  RSC ADVANCES 6 11 8964 - 8970 2016年 [査読有り][通常論文]
   

  Resistive switching gallium oxide base thin films with tailored oxygen deficiency were fabricated by rf cosputtering of Ga2O3 and Cr. XPS and STEM-EDX analyses were used to determine that the resultant film was made of a homogeneous oxide glass layer with mixed valance states of Ga(III)-Ga(I). The amount of Ga(I) and the corresponding oxygen deficiency was precisely controlled because the following redox reaction subsequently progresses within the deposited films: 3Ga(III) + 2Cr(0) -> 3Ga(I) + 2Cr(III). The on/off resistance ratio was largely varied by changing the Ga(I) fraction in relation to the oxide ion conductivity, and Ga0.82Cr0.18O1.2 thin film was found to exhibit an optimal switching performance. The film resistance state was tunable by 100's of ms pulse biasing and was incrementally changed by increasing the applied pulse numbers. The strongly time-dependent switching events and area dependent current level of Cr-GaOx films were distinct from the abrupt switching behavior of the filamentary mechanism TiOx thin film devices. It was demonstrated that rf cosputtering of the metal oxides and the corresponding oxygen scavenging metals was a powerful technique to design the bulk state resistive switching devices based on nonstoichiometric metal oxide thin films.
• Reversible redox reaction of high valence state neodymium chromate(V) by insertion and desertion of hydrogen

  Y. Aoki, K. Kuroda, E. Tsuji, H. Habazaki

  Solid State Ionics 285 175 - 179 2016年 [査読有り][通常論文]
  
• Growth of barrier-type anodic films on magnesium in ethylene glycol electrolytes containing fluoride and water

  Hiroki Habazaki, Fumitaka Kataoka, Khurram Shahzad, Etsushi Tsuji, Yoshitaka Aoki, Shinji Nagata, Peter Skeldon, George E. Thompson

  ELECTROCHIMICA ACTA 179 402 - 410 2015年10月 [査読有り][通常論文]
   

  This study demonstrates the formation of uniform barrier-type anodic films on magnetron-sputtered magnesium films at high current efficiency in ethylene glycol electrolytes containing 0.1 mol dm (3) NH4F and various concentrations (0.1-28 mol dm (3)) of H2O. The anodic films containing a crystalline MgF2 phase develop both at the metal/film and film/electrolyte interfaces due to simultaneous migrations of anions inwards and cations outwards, respectively. When a Mg - 1.2 at% Au/Mg bilayer film is anodized, initial prior oxidation of magnesium proceeds with gold atoms accumulating in a thin layer beneath the anodic film. The accumulated gold atoms are incorporated into the anodic film as a band when the alloy layer is completely anodized. Fluoride-containing gold species are formed by the incorporation and the gold species migrate outwards at a rate of 0.4 times the rate of Mg2+ ions. The addition of phosphate in the electrolyte results in the formation of an amorphous anodic film, and the phosphate incorporated into the anodic film is distributed throughout the film thickness. The transport number of cations is also influenced by the phosphate incorporation. (C) 2015 Elsevier Ltd. All rights reserved.
• Highly durable platelet carbon nanofiber-supported platinum catalysts for the oxygen reduction reaction

  Etsushi Tsuji, Takenori Yamasaki, Yoshitaka Aoki, Soo-Gil Park, Ken-ichi Shimizu, Hiroki Habazaki

  CARBON 87 1 - 9 2015年06月 [査読有り][通常論文]
   

  We report the preparation and characterization of highly durable platinum catalysts supported on platelet-structure carbon nanofibers (Pt/p-CNFs) for the oxygen reduction reaction. The p-CNFs were prepared by liquid phase carbonization of polyvinyl chloride using a porous anodic alumina template at 600 degrees C; their degree of graphitization was increased by the subsequent heat treatment at higher temperatures of up to 1400 degrees C. The platinum nanoparticles with similar to 3 nm diameter were deposited more uniformly on the p-CNFs compared with those on the commercial Ketjen black (KB). The catalytic activity and durability of the Pt/p-CNFs for the oxygen reduction reaction (ORR) in H2SO4 solution were improved by increasing the heat-treatment temperature of p-CNFs. The durability of the Pt/p-CNFs was much higher than that of Pt/KB; in particular, a loss of less than 10% was observed in the ORR activity of Pt/p-CNF heat-treated at 1400 degrees C after potential cycling from 0.5 to 1.5 V vs. RHE for 200 cycles in an argon-saturated H2SO4 aqueous solution. (C) 2015 Elsevier Ltd. All rights reserved.
• Development of direct ammonia fueled hydrogen membrane fuel cell

  Y. Aoki, S. Kobayashi, T. Yamaguchi, E. Tsuji, H. Habazaki

  ECS Transactions 68 1 2735 - 2738 2015年 [査読有り][通常論文]
   

  Hydrogen membrane fuel cells, HMFC, were fabricated by RF sputtering deposition of BaCe< sup> 0.8< /sup> Y< sup> 0.2< /sup> O< sup> 3-δ< /sup> thin films on Pd solid anode. The HMFC can give OCV of 1.1 V and peak power density of 300 mW cm< sup> -2< /sup> at 600°C with H< inf> 2< /inf> fuels. On the other hand, the direct NH< inf> 3< /inf> fueled HMFC reveals OCV of 0.95 V and peak power density of 80 mW cm< sup> -2< /sup> at 600°C. The impedance spectroscopy reveals that anodic polarization is the main contribution to the loss in HMFC.
• Formation of self-organized porous anodic films on iron and stainless steels

  H. Habazaki, K. Shahzad, T. Hiraga, E. Tsuji, Y. Aoki

  ECS Transactions 69 2 211 - 223 2015年 [査読無し][通常論文]
   

  High purity iron and commercial Type 304 and 430 stainless steels were anodized in ethylene glycol electrolytes containing fluoride and water. When iron was anodized in the electrolytes containing relatively high water concentrations (≥1.5 mol dm-3) at 50 V, porous anodic films with scalloped metal/film interface were developed. In contrast, the anodic films formed in the electrolytes with low water concentrations (≤0.5 mol dm-3) resulted in the flat metal/film interface. In addition, the interpore distance became smaller with respect to the thickness of barrier layer when the water concentration is reduced. These morphological changes may be associated with the change in the composition of the anodic films. Anodizing of stainless steels was dependent upon the type of stainless steel a steady-state current continued up to ~160 V on Type 430 stainless steel, while exponential current increase occurred above ~50 V on Type 304 stainless steel during potentiodynamic anodizing. The thickness of the barrier layer and the morphology of the porous layer were largely dependent upon the type of stainless steel. Based on such findings, the mechanism of film growth was discussed.
• GDOES Depth Profile Analysis of Interfacial Enrichment of Copper during Anodizing of Al-Cu Alloy

  H. Habazaki, M. Uemura, K. Fushimi, E. Tsuji, Y. Aoki, S. Nagata

  Journal of The Surface Finishing Society Japan 66 12 670 - 672 一般社団法人 表面技術協会 2015年 [査読有り][通常論文]
  
• Formation and field-assisted dissolution of anodic films on iron in fluoride-containing organic electrolyte

  Khurram Shahzad, Etsushi Tsuji, Yoshitaka Aoki, Shinji Nagata, Hiroki Habazaki

  ELECTROCHIMICA ACTA 151 363 - 369 2015年01月 [査読有り][通常論文]
   

  Magnetron-sputtered iron films were potentiodynamically anodized at two different sweep rates to 50 V in an ethylene glycol electrolyte containing ammonium fluoride and water. At a high sweep rate of 1.0 V s(-1), a barrier-type anodic film was formed even though the current efficiency was as low as similar to 50%. In contrast, a nanoporous anodic film developed at a low sweep rate of 0.05 V s(-1), and the film-formation efficiency reduced to 37%. The main part of the anodic films consists of iron (III) hydroxyfluoride with a thin inner layer composed of FeF3. The inner fluoride layer is formed owing to the faster inward migration of fluoride ions compared to that of the oxygen species. During immersion or re-anodizing of the iron specimen with an approximately 100-nm-thick, barrier-type anodic film at and below 15 V, thinning of the anodic film proceeded uniformly and film dissolution was enhanced by applying an electric field. The impact of the electric field on film formation and dissolution is discussed. (C) 2014 Elsevier Ltd. All rights reserved.
• Corrosion protection of iron using porous anodic oxide/conducting polymer composite coatings

  Yoshiki Konno, Etsushi Tsuji, Yoshitaka Aoki, Toshiaki Ohtsuka, Hiroki Habazaki

  FARADAY DISCUSSIONS 180 479 - 493 2015年 [査読有り][通常論文]
   

  Conducting polymers (CPs), including polypyrrole, have attracted attention for their potential in the protection of metals against corrosion; however, CP coatings have the limitation of poor adhesion to metal substrates. In this study, a composite coating, comprising a self-organized porous anodic oxide layer and a polypyrrole layer, has been developed on iron. Because of electropolymerization in the pores of the anodic oxide layer, the composite coating showed improved adhesion to the substrate along with prolonged corrosion protection in a NaCl aqueous corrosive environment. The anodic oxide layers are formed in a fluoride-containing organic electrolyte and contain a large amount of fluoride species. The removal of these fluoride species from the oxide layer and the metal/oxide interface region is crucial for improving the corrosion protection.
• Electrochemical Analysis of Hydrogen Membrane Fuel Cells with Amorphous Zirconium Phosphate Thin Film Electrolyte

  Ryo Nonaka, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

  ELECTROCHEMISTRY 82 10 859 - 864 2014年10月 [査読有り][通常論文]
   

  An electrochemical analysis was conducted with respect to a hydrogen membrane fuel cell (HMFC) comprising proton-conducting, amorphous zirconium phosphate, a-ZrP2.5O8.9H1.3, thin film electrolyte supported on a dense Pd anode. The HMFC gave rise to an OCV of 1.0 V, but the maximum power density was limited and was about 1 mW cm(-2) at 400 degrees C. The impedance spectroscopy revealed that the interfacial polarizations were decreased by two orders of magnitude when the cell configuration was changed from the fuel cell setup to the hydrogen concentration cell with an anode symmetric configuration. These results indicated that the polarization losses at the solid-solid anode interface are not a main contribution to the voltage loss of the HMFC. The large cathode polarization might be attributed to the lessened conductivity of amorphous zirconium phosphate electrolyte thin film formed on a precious metal electrode. (C) The Electrochemical Society of Japan, All rights reserved.
• Efficient growth of anodic films on magnesium in organic electrolytes containing fluoride and water

  Hiroki Habazaki, Fumitaka Kataoka, Etsushi Tsuji, Yoshitaka Aoki, Shinji Nagata, Peter Skeldon, George E. Thompson

  ELECTROCHEMISTRY COMMUNICATIONS 46 30 - 32 2014年09月 [査読有り][通常論文]
   

  The present study reports, for the first time, the highly efficient formation of barrier-type anodic films, with flat and parallel metal/film and film/electrolyte interfaces, on magnesium in ethylene glycol electrolytes containing ammonium fluoride and water. The anodizing voltage increases linearly with time during galvanostatic anodizing at 10Am(-2) up to 350 V.The anodic film formed to 200V is 247 nm thick, containing a crystalline MgF2 phase. Analysis by Rutherford backscattering spectroscopy discloses the film composition of MgF1.8O0.1 and Pilling-Bedworth ratio (PBR) of 1.67. The PBR value greater than unity and the formation of chemically stable fluoride-based films may contribute to the film growth at high current efficiency. (C) 2014 Elsevier B.V. All rights reserved.
• Morphological control of anodic crystalline TiO2 nanochannel films for use in size-selective photocatalytic decomposition of organic molecules

  E. Tsuji, Y. Taguchi, Y. Aoki, T. Hashimoto, P. Skeldon, G. E. Thompson, H. Habazaki

  APPLIED SURFACE SCIENCE 301 500 - 507 2014年05月 [査読有り][通常論文]
   

  We report the size-selective photocatalytic decomposition of organic molecules using crystalline anodic TiO2 nanochannel films as the photocatalyst. The porous TiO2 films were formed by anodizing titanium at 20 V in glycerol electrolyte containing various amounts of K3PO4, K2HPO4, and KH2PO4 at 433K. Regardless of the electrolyte composition, the as-formed TiO2 films had a crystalline anatase structure. The basicity of the electrolyte markedly influenced the morphology of the TiO2 nanochannel films; more regular nanochannels developed with increasing basicity of the electrolyte. Because the diameter of the nanochannels in the films formed in a basic electrolyte was as small as similar to 10 nm, the anodic TiO2 nanochannel films with a thickness of 5 mu m revealed a selective photocatalytic decomposition of methylene blue (MB) in a mixture of MB and direct red 80 (DR) kept under UV irradiation. The importance of the diameter of the nanochannels and their uniformity for size-selective decomposition of organic molecules were investigated. (C) 2014 Elsevier B.V. All rights reserved.
• Bulk mixed ion electron conduction in amorphous gallium oxide causes memristive behaviour

  Yoshitaka Aoki, Carsten Wiemann, Vitaliy Feyer, Hong-Seok Kim, Claus Michael Schneider, Han Ill-Yoo, Manfred Martin

  NATURE COMMUNICATIONS 5 3 3473/1 - 3473/9 2014年03月 [査読有り][通常論文]
   

  In thin films of mixed ionic electronic conductors sandwiched by two ion-blocking electrodes, the homogeneous migration of ions and their polarization will modify the electronic carrier distribution across the conductor, thereby enabling homogeneous resistive switching. Here we report non-filamentary memristive switching based on the bulk oxide ion conductivity of amorphous GaOx (x similar to 1.1) thin films. We directly observe reversible enrichment and depletion of oxygen ions at the blocking electrodes responding to the bias polarity by using photoemission and transmission electron microscopies, thus proving that oxygen ion mobility at room temperature causes memristive behaviour. The shape of the hysteresis I-V curves is tunable by the bias history, ranging from narrow counter figure-eight loops to wide hysteresis, triangle loops as found in the mathematically derived memristor model. This dynamical behaviour can be attributed to the coupled ion drift and diffusion motion and the oxygen concentration profile acting as a state function of the memristor.
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• Fabrication of superoleophobic hierarchical surfaces for low-surface-tension liquids

  Katsutoshi Nakayama, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  RSC ADVANCES 4 58 30927 - 30933 2014年 [査読有り][通常論文]
   

  This study demonstrates the fabrication of hierarchical surfaces with super-repellency even for low-surface-tension liquids, including octane (surface tension of 21.7 mN m(-1)). Dual-pore surfaces were prepared by a combination of practical wet processes on an aluminium substrate: chemical etching, anodizing, and organic monolayer coating. The size of the larger pores formed by the chemical etching of aluminium is controlled by the concentration of HCl in the CuCl2/HCl etching solution. The etched aluminium is then anodized to introduce nanopores, followed by a pore-widening treatment that controls the nanopore size and porosity. The repellency for low-surface-tension liquids is enhanced by increasing the size of the larger pores as well as the porosity of the walls of the larger pores in this dual-pore morphology. Under optimized morphology with a fluoroalkyl-phosphate monolayer coating, an advancing contact angle close to 160 degrees, a contact angle hysteresis of less than 5 degrees and a sliding angle of 10 degrees is achieved even for octane.
• Highly Enhanced Corrosion Resistance of Stainless Steel by Sol-Gel Layer-by-Layer Aluminosilicate Thin Coatings

  Hiroki Habazaki, Taiki Kimura, Yoshitaka Aoki, Etsushi Tsuji, Takayoshi Yano

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 161 1 C57 - C61 2014年 [査読有り][通常論文]
   

  In this study, aluminosilicate sol-gel coatings were deposited on Type 430 stainless steel by multiple spin casting cycles. Amorphous aluminosilicate coatings, 65 nm thick, were prepared from precursor solutions with 50, 100, and 500 mmol dm(-3) total concentrations of aluminum and silicon species (molar ratio of Al/Si = 1/4) by 10, 5, and 1 spin casting cycles, respectively. Although the obtained coatings had a similar composition with a molar ratio of Al/Si = 25/75, the coatings with increased density were formed by reducing the concentration of precursor solution. The pitting potentials of the coated stainless steels, measured by potentiodynamic polarization in 3.5% NaCl solution, increased remarkably (to 1.1 V vs Ag/AgCl) with a decrease in the concentration of precursor solution. Cyclic corrosion tests, consisting of 30 cycles of spraying of 5% NaCl solution at 35 degrees C for 2 h, drying at 60 degrees C for 4 h, and wetting at 50 degrees C and >95% relative humidity for 2 h, revealed highly improved corrosion resistance. Layer-by-layer sal-gel deposition using diluted precursor solutions is an effective way to obtain highly protective coatings. (C) 2013 The Electrochemical Society.
• Mixed Proton Electron Conductivity of Calcium Chromate(V) Apatite

  Yoshitaka Aoki, Kazumasa Kikutani, Etsushi Tsuji, Hiroki Habazaki

  ECS ELECTROCHEMISTRY LETTERS 3 10 F61 - F64 2014年 [査読有り][通常論文]
   

  This is the first report to investigate on the electrical conductivity of unusual high valence state pentavalent chromium oxides in terms of defect thermodynamics. Calcium chromium(V) apatite was prepared as a single phase, and the electrical conductivity was examined as a function of oxygen partial pressure p(O2). The conductivity was increased at higher p(O2) in wet atmosphere but it was not dependent on p(O2) in dry atmosphere. The water concentration cell gives stable electromotive force. The features disclosed that the chromium(V) apatite reveals proton electron mixed conductivity under wet oxidative condition. (C) 2014 The Electrochemical Society. All rights reserved.
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• Formation and dielectric properties of anodic films formed on ta-w alloys at various formation voltages

  Masatoshi Ishizuka, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  Electrochemistry 81 10 840 - 844 2013年10月 [査読有り][通常論文]
   

  Barrier-type anodic films are formed on magnetron sputtered Ta-W alloy films to various formation potentials in 0.1 moldm-3 ammonium pentaborate electrolyte. The anodic films consist of two layers, comprising an outer thin Ta2O5 layer free from tungsten species and an inner layer containing both tantalum and tungsten species. Slower migration of W6+ ions with respect to Ta5+ ions results in the formation of the two-layered films. Because of the absence of more soluble tungsten species in the outer layer, the anodic films grow at high current efficiency. The reciprocal of capacitance of the anodic films changes linearly with formation voltage, as a consequence of linear thickening of the anodic films with the formation potential. The capacitance is enhanced by the addition of tungsten, particularly at low formation potential. The shift of the potential, at which the anodic film growth commences, to the noble direction, contributes to the enhanced capacitance at the low formation voltages. © The Electrochemical Society of Japan, All rights reserved.
• Observation of self-assembled layers of alkyl phosphonic acid on aluminum using low-voltage scanning electron microscopy and AFM

  H. Sato, T. Fujii, E. Tsuji, Y. Aoki, K. Shimizu, P. Skeldon, G. E. Thompson, H. Habazaki

  SURFACE AND INTERFACE ANALYSIS 45 10 1441 - 1445 2013年10月 [査読有り][通常論文]
   

  Self-assembled alkyl phosphate layers have been formed on a flat, anodized aluminum substrate in dilute ethanol solution containing 2wt% n-tetradecylphosphonic acid (TDP) and examined by low-voltage scanning electron microscopy as well as atomic force microscopy and X-ray photoelectron spectroscopy. Locally, multi-layered alkyl phosphate films have been formed on aluminum, being clearly observed by a low-voltage scanning electron microscope operated at less than 1kV. Atomic force microscopy observations disclosed that bilayers of tetradecylphosphonic acid are stacked on the substrate to form multilayers. The present study revealed that the uniform self-organized monolayer is not always formed readily on an oxidized aluminum surface. Copyright (c) 2013 John Wiley & Sons, Ltd.
• Characterization of self-assembled monolayer on anodized aluminum by XPS, AFM and low-voltage SEM

  H. Habazaki, H. Sato, E. Tsuji, Y. Aoki, K. Shimizu

  ECS Transactions 58 41 75 - 83 2013年 [査読有り][通常論文]
   

  Organic layers of tetradecylphosphonic acid (TDP) and octadecyltrietoxysilane (OES) are formed on flat anodized aluminum surfaces by a simple immersion process. The organic layers are characterized by dynamic contact angle measurements for water, AFM, low-voltage SEM and angle-resolved XPS. The results indicate that a self-assembled monolayer is formed using TDP, but not for OES. Plasma surface treatment prior to the coating was found to significantly influence the formation of organic layers. © 2014 The Electrochemical Society.
• High Proton Conductivity in Anodic ZrO2-WO3-SiO2 Nanofilms

  Ke Ye, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

  SOLID STATE IONIC DEVICES 9 - ION CONDUCTING THIN FILMS AND MULTILAYERS 50 27 193 - 201 2013年 [査読有り][通常論文]
   

  The proton conductivity of the anodic ZrO2-WO3-SiO2 nanofilms prepared by anodizing of sputter-deposited Zr37W47Si16 alloy at several formation voltages for 1.8 ks in 0.1 mol dm(-3) phosphoric acid electrolyte at 20 degrees C has been examined below 250 degrees C in various environments. The proton conductivity activated by thermal treatment at 250 degrees C is not influenced by the presence of O-2 and H2O in the atmosphere. However, the conductivity is enhanced by one order of magnitude in H-2-containing atmosphere. The H-2-induced conductivity enhancement is reversible; the enhanced conductivity is returned to an original value by exposing again in an O-2-containing atmosphere.
• Influence of Yttrium Addition on the High Capacitance of ZrO2-SiO2 Nanocomposite Anodic Oxide Films.

  Ishizuka M, Tsuji E, Aoki Y, Hyono A, Ohtsuka T, Sakaguchi N, Nagata S, Habazaki H

  ELECTROCHEMICAL CAPACITORS 50 43 245 - 254 2013年 [査読有り][通常論文]
   

  The sputter-deposited Zr-Si-Y film was anodized to form a high capacitance composite anodic film, comprising a tetragonal ZrO2 nanocrystalline phase and a silicon-enriched amorphous phase. It was found that the nanocomposite anodic film, as well as the yttrium-free ZrO2-SiO2 anodic film, showed markedly increased capacitance compared with the anodic film ZrO2 film on zirconium. The incorporation of yttrium species to the anodic ZrO2-SiO2 film did not change the thickness and permittivity of the anodic oxide film, although a thicker anodic film was formed on zirconium by the incorporation of yttrium, which may introduce oxygen vacancies in the crystalline ZrO2. The findings suggest that in the composite ZrO2-SiO2 anodic films the film thickness is mainly controlled by the silicon-enriched amorphous phase.
• Hydrogen membrane fuel cells with metal/insulator/metal structure

  Y. Aoki, R. Nonaka, H. Habazaki

  ECS Transactions 57 1 911 - 916 2013年 [査読有り][通常論文]
   

  Novel thin film fuel cell based on the 100 nm-thick electrolyte of amorphous ZrP2.5Ox, working at 400°C, was demonstrated. The hydrogen permeable membrane fuel cell (HMFC) using a Pd foil as a nonporous solid anode was fabricated. Ni interlayer of several hundreds nm thickness was introduced between the Pd anode and the ZrP2.5O x electrolyte in order to suppress the deterioration of the electrolyte nanofilm by the deformation of the Pd anode during hydrogen absorption. In the ZrP2.5Ox electrolyte the transport number of proton was unity at 400°C as determined by an EMF measurement. The modification of the Ni anode surface by an ultrathin Pt or Pd layer effectively decreased the anode/electrolyte interfacial polarization. Consequently, the HMFC revealed the OCV of 1.0 V and the maximum power density of 3.6 mW cm -2 at 400°C. © The Electrochemical Society.
• Compositional Dependence of the Proton Conductivity of Anodic ZrO2-WO3-SiO2 Nanofilms at Intermediate Temperatures

  Ke Ye, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 160 9 F1096 - F1102 2013年 [査読有り][通常論文]
   

  Novel proton-conducting ZrO2-WO3-SiO2 nanofilms of various compositions and thicknesses (similar to 50 to similar to 300 nm) have been prepared by anodizing of magnetron-sputtered Zr-W-Si alloys in 0.1 mol dm(-3) phosphoric acid electrolyte at 20 degrees C. All the anodic oxide nanofilms examined reveal efficient proton conductivity after post-annealing at 250 degrees C. Further increase in the post-annealing temperature results in the conductivity degradation for the anodic oxide nanofilms on the alloy containing only 5 at% silicon, while the high conductivity is maintained even after post-annealing at 300 degrees C for those containing 15 at% or more silicon. The proton conductivity is dependent upon tungsten content; the conductivity of 5 x 10(-6) S cm(-1) for the similar to 100 nm-thick films on the Zr31W55Si14 at 100 degrees C is approximately 10 times that on the Zr48W37Si15. The anodic oxide nanofilms consist of two layers, comprising a thin outer ZrO2 layer and an inner ZrO2-WO3-SiO2 layer. Both layers show thickness-dependent conductivity and the proton conductivity of the two-layer anodic films is enhanced one order of magnitude by reducing the film thickness from similar to 300 nm to similar to 100 mu. Different mechanisms are proposed for the thickness dependence of the conductivity of the outer and inner layers. (C) 2013 The Electrochemical Society. All rights reserved.
• Preparation of non-annealed anatase TiO2 film on ITO substrate by anodizing in hot phosphate/glycerol electrolyte for dye-sensitized solar cells

  Etsushi Tsuji, Naoto Hirata, Yoshitaka Aoki, Hiroki Habazaki

  MATERIALS LETTERS 91 39 - 41 2013年01月 [査読有り][通常論文]
   

  In this study, mesoporous TiO2 films were formed on ITO conductive glasses by anodizing of titanium thin films without post-annealing. The titanium thin films, similar to 200 nm thick, sputter-deposited on to the ITO substrates were anodized at 20 V in a phosphate/glycerol electrolyte at 433 K. A completely. transparent TiO2 specimen was obtained by anodizing for 60 s. The as-anodized mesoporous,TiO2 films consisted of anatase, even without post-annealing. The transparent mesoporous TiO2 films anodized for a suitable time showed much better photoelectrochemical performance than the post-annealed TiO2 nanotubular film. (C) 2012 Elsevier B.V. All rights reserved.
• Important Role of Nanopore Morphology in Superoleophobic Hierarchical Surfaces

  Takashi Fujii, Hina Sato, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  JOURNAL OF PHYSICAL CHEMISTRY C 116 44 23308 - 23314 2012年11月 [査読有り][通常論文]
   

  This work reports the importance of nanopore morphology in designing super liquid-repellent submicropillar/nanopore hierarchical surfaces. The hierarchical surfaces were fabricated using a combined process of oblique angle sputter deposition of aluminum with subsequent anodizing, and the surfaces were coated with a fluorinated alkyl phosphate layer to reduce the surface energy. The size of the nanopores, the interpore distance, and the porosity of the anodic films on the submicrometer pillars were controlled by varying the anodizing and pore-widening conditions. The present study demonstrates that super liquid repellency can be achieved on intrinsically oleophilic surfaces by introducing hierarchical submicropillar/nanopore morphology even for oils with surface energies as low as similar to 25 mN m(-1). The porosity in the submicrometer pillars was a key factor in influencing the contact angle hysteresis; higher porosity is needed to reduce the contact angle hysteresis.
• Photo-induced properties of non-annealed anatase TiO2 mesoporous film prepared by anodizing in the hot phosphate/glycerol electrolyte

  Yoshiaki Taguchi, Etsushi Tsuji, Yoshitaka Aoki, Hiroki Habazaki

  APPLIED SURFACE SCIENCE 258 24 9810 - 9815 2012年10月 [査読有り][通常論文]
   

  In this study, anatase crystalline TiO2 mesoporous film was formed by anodizing of titanium specimens without annealing procedures. The specimens were anodized at 3 and 20 V in 0.6 mol dm(-3) K2HPO4 and 0.2 mol dm(-3) K3PO4/glycerol electrolyte at 433 K. The obtained films had mesoporous structures with pore diameters as small as similar to 10 nm. The mesoporous film formed at 20 V without annealing (MP-20V) was a mixture of amorphous phase and nanograined anatase, which clearly showed strong < 0 0 1 > preferred orientation, whereas that at 3 V was completely amorphous. Even without annealing, the MP-20V showed high photocatalytic activities for decomposition of water and methylene blue. In contrast, the anodic TiO2 nanotube film formed in NH4F/ethylene glycol electrolyte revealed photocatalytic activities only after annealing at 723 K, because of the amorphous nature of the as-anodized nanotube film. The MP-20V film also showed superhydrophilicity with UV light irradiation. (C) 2012 Elsevier B. V. All rights reserved.
• Thickness dependence of proton conductivity of anodic ZrO2–WO3–SiO2 nanofilms

  K. Ye, Y. Aoki, E. Tsuji, S. Nagata, H. Habazaki

  Journal of Power Sources 205 194 - 200 2012年05月 [査読有り][通常論文]
   

  Amorphous ZrO2-WO3-SiO2 nanofilms are simply prepared by anodizing of sputter-deposited Zr37W47Si16 alloy at several formation voltages for 1.8 ks in 0.1 mol dm(-3) phosphoric acid electrolyte at 20 degrees C. Efficient proton conductivity was observed after thermal treatment at 250 degrees C with the conductivity enhanced by reducing the film thickness. The conductivity is enhanced more than one order of magnitude by reducing the thickness from 300 to 140 nm. The anodic oxide films consist of two layers, comprising a thin outer ZrO2 layer free from silicon and tungsten species and an inner main layer containing all zirconium, silicon and tungsten species. The thickness-dependent conductivity of the anodic ZrO2-WO3-SiO2 films is associated with the conductivity of the outer ZrO2 layer, which increases exponentially with reducing the film thickness. The area-specific resistivity of 0.14 Omega cm(2), which is below the minimum requirement (0.2 Omega cm(2)) for a practical electrolyte membrane in commercial fuel cells, is achieved at a temperature at 225 degrees C for 100 nm-thick anodic ZrO2-WO3-SiO2 films. (C) 2012 Elsevier B.V. All rights reserved.
• Growth and field crystallization of anodic films on Ta–Nb alloys

  S. Komiyama, E. Tsuji, Y. Aoki, H. Habazaki

  Journal of Solid State Electrochemistry 16 4 1595 - 1604 2012年04月 [査読有り][通常論文]
   

  The growth behavior of amorphous anodic films on Ta-Nb solid solution alloys has been investigated over a wide composition range at a constant current density of 50 A m(-2) in 0.1 mol dm(-3) ammonium pentaborate electrolyte. The anodic films consist of two layers, comprising a thin outer Nb2O5 layer and an inner layer consisting of units of Ta2O5 and Nb2O5. The outer Nb2O5 layer is formed as a consequence of the faster outward migration of Nb5+ ions, compared with Ta5+ ions, during film growth under the high electric field. Their relative migration rates are independent of the alloy composition. The formation ratio, density, and capacitance of the films show a linear relation to the alloy composition. The susceptibility of the anodic films to field crystallization during anodizing at constant voltage increases with increasing niobium content of the alloy.
• In situ X-ray absorption spectroscopy for identification of lead species adsorbed on a nickel surface in acidic perchlorate solution

  Masahiro Seo, Koji Fushimi, Yoshitaka Aoki, Hiroki Habazaki, Masayuki Inaba, Mitsutoshi Yokomizo, Takazumi Hayakawa, Takenori Nakayama

  JOURNAL OF ELECTROANALYTICAL CHEMISTRY 671 7 - 15 2012年04月 [査読有り][通常論文]
   

  In situ X-ray absorption spectroscopy (XAS) using a synchrotron radiation was applied to identify the Pb species adsorbed on Ni surface in acidic perchlorate solution containing 10(-4) M Pb2+ with relation to the Pb-induced stress corrosion cracking (Pb-SCC) of Ni-base alloys used as tubing materials of steam generators in nuclear power plants. The periodical emersion method under potentiostatic polarization, using the Ni plate with large specific surface area (surface roughness, S-r = 78.3) as a working electrode, was developed to detect sensitively the sub-monolayer coverage of Pb on Ni. The Pb L-III absorption spectra in a scanning XAS mode were measured by monitoring the Pb L alpha fluorescence line. The Pb L-III absorption near-edge structure (XANES) at the potential more positive than -0.245 V (SHE) corresponding to the equilibrium potential of Pb-electrodeposition in 10(-4) M Pb2+ solution has revealed that the Pb species adsorbed on the Ni surface are metallic, providing the clear evidence of underpotential deposition (UPD) of Pb on the Ni surface. Moreover, the extended X-ray absorption fine structure (EXAFS) analysis was performed with a two-shell fit involving Pb-Ni and Pb-Pb interactions assuming that the Ni (1 1 1) plane is mainly exposed to the solution. The EXAFS results were convincingly explained in terms of the Pb-UPD model which represents the coexistence of the surface alloy phase and the adlayer with the same p(2 x 2) structure in the narrow potential range of -0.185 V (SHE) to -0.245 V (SHE). (C) 2012 Elsevier B.V. All rights reserved.
• Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation

  S. P. Sah, E. Tsuji, Y. Aoki, H. Habazaki

  Corrosion Science 55 90 - 96 2012年02月 [査読有り][通常論文]
   

  Sequential anodic and cathodic pulse voltages were applied on anodised Al micro-electrodes in alkaline silicate electrolyte to explore the role of cathodic pulse in AC or bipolar plasma electrolytic oxidation (PEO) process. SEM observation was carried out to observe the sites of anodic and cathodic breakdown and their morphologies. The prior anodic breakdown accelerated the cathodic breakdown at -50 V, and the acceleration was associated with the preferential cathodic breakdown at the anodic breakdown sites. However, the succeeding anodic breakdown during applying anodic pulse of 420 V for 2 ms was highly suppressed at the cathodic breakdown sites. This would randomise the anodic breakdown sites. Such role may contribute to the formation of rather uniform coatings on aluminium in this electrolyte without large discharge channels when larger cathodic current is applied with respect to the anodic current in AC PEO. (C) 2011 Elsevier Ltd. All rights reserved.
• Evaluation of Simplified Repeated Resistance Training System for Severe Hemiplegic Stroke Patient

  Michito Yasukita, Yuki Iida, Kazunori Yamazaki, Noritaka Sato, Yoshifumi Morita, Hiroyuki Ukai, Yoshiaki Takagi, Yoshitaka Aoki, Hirofumi Tanabe, Rumi Tanemura

  2012 12TH INTERNATIONAL CONFERENCE ON CONTROL, AUTOMATION AND SYSTEMS (ICCAS) 1566 - 1569 2012年 

  We have developed a three-dimensional force display robot (3D robot) to discover and embody needs in rehabilitation site. Then we have exchanged opinions with therapists by using the 3D robot together in rehabilitation site. From a therapist' needs we have developed repeated resistance training system by using the 3D robot as one of the application of the 3D robot. On the basis of the results we have developed a simplified repeated resistance training system equipped with a user interface for easy operation for therapists. Moreover, we have developed a brace for fixation as the attachment between the training system and the patient's arm. In this paper, we perform the functional evaluation of the simplified repeated resistance training system and the brace in the clinical site. These results are based on the opinions from the therapist and the patient. Moreover, we verify the therapeutic effects of the repeated resistance training using the simplified system for a hemiplegic stroke patient. The AROMs of pronation and supination of the patient were improved after repeated resistance training using the simplified system.
• Fabrication of super-oil-repellent surfaces by two-step anodizing of aluminum

  H. Habazaki, T. Fujii, E. Tsuji, Y. Aoki

  ECS Transactions 50 37 217 - 224 2012年 [査読有り][通常論文]
   

  In this study, hierarchical dual pore surfaces have been developed by two-step anodizing of aluminum. The first anodizing has been carried out at 390 V in 2 wt% citric acid, and then, the resultant anodic film has been dissolved to disclose the scalloped aluminum substrate with a cell size of ∼900 nm. Subsequently, the second anodizing has been carried out at 25 V in 0.3 mol dm-3 sulfuric acid electrolyte to generate smaller nanopores. The size of nanopores has been further controlled by pore-widening treatment in 5 wt% phosphoric acid at 303 K. After coating with a fluoroalkyl phosphate monolayer to reduce the surface energy, the dual pillar surfaces with enlarged nanopores show super-repellency even for rapeseed oil as well as for water. © The Electrochemical Society.
• Formation of self-organized nanoporous anodic films on carbon steel

  Y. Konno, S. Yang, E. Tsuji, Y. Aoki, P. Skeldon, G. E. Thompson, H. Habazaki

  ECS Transactions 50 37 183 - 190 2012年 [査読有り][通常論文]
   

  The growth behavior of nanoporous anodic films on carbon steel containing 0.213 mass% carbon has been examined during anodizing in ethylene glycol containing 0.1 mol dm-3 NH4F and 0.5 mol dm-3 H2O. The nanopores in the anodic films are generated preferentially along with steps and at "kink-like" sites of the steel surface generated by rf-GD sputtering. The steel contains carbide precipitates with a size of 50-800 nm. The anodic oxide formed on the carbide phase is more chemically soluble during anodizing, producing pits in the anodic films. © The Electrochemical Society.
• Percolative proton conductivity of sol-gel derived amorphous aluminosilicate thin films

  Yoshitaka Aoki, Akihisa Harada, Aiko Nakao, Toyoki Kunitake, Hiroki Habazaki

  PHYSICAL CHEMISTRY CHEMICAL PHYSICS 14 8 2735 - 2742 2012年 [査読有り][通常論文]
   

  The finite size effect of proton conductivity of amorphous aluminosilicate thin films, a-AlnSi1-nOx (n = 0.07, 0.1, 0.2, 0.3 and 0.45), prepared by a sol-gel process was investigated by experimental and numerical techniques. High-resolution TEM clarified that a-AlnSi1-nOx films had the heterogeneous nanoscale microstructures comprised of the ion-conducting, condensed glass microdomain and the poor-conductive, uncondensed glass microdomain. s of the films with n <= 0.1 exponentially increased upon decreasing thickness in the sub-100 nm range because the volume fraction of conductive domains was less than the percolation threshold and cluster size scaling of the conductive domain was operative. The numerical simulation suggested that conductance of the condensed domain was higher than that of the uncondensed domain by 2 orders of magnitude. Volume fractions of the condensed domain increased with increasing Al/Si molar ratio and were over the percolation threshold (24.5%) with n >= 0.2. However, conductance of the condensed domain decreased with increasing Al/Si ratio with n >= 0.2 because the aluminosilicate glass framework made of 4-fold-connected MO4 tetrahedra was deformed by forming the octahedral AlO6 moieties, as checked by Al K-edge XAS. It was found that the optimal Al/Si composition in terms of the conductance of the condensed domain is not in coincidence with that in terms of the average conductivity of the films.
• Formation and dielectric properties of anodic oxide films on Zr-Al alloys

  Shun Koyama, Yoshitaka Aoki, Shinji Nagata, Hiroki Habazaki

  JOURNAL OF SOLID STATE ELECTROCHEMISTRY 15 10 2221 - 2229 2011年10月 [査読有り][通常論文]
   

  Zr-Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm(-3) ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy, and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO(2) with the former being a major phase. Two-layered anodic oxide films, comprising an outer thin amorphous layer and an inner main layer of crystalline tetragonal ZrO(2) phase, are formed on the Zr-Al alloys containing 5 to 16 at.% aluminum. Further increase in the aluminum content to 26 at.% results in the formation of amorphous oxide layer throughout the thickness. The anodic oxide films become thin with increasing aluminum content, while the relative permittivity of anodic oxide shows a maximum at the aluminum content of 11 at.%. Due to major contribution of permittivity enhancement, the maximum capacitance of the anodic oxide films is obtained on the Zr-11 at.% Al alloy, being 1.7 times than on zirconium at the formation voltage of 100 V.
• Fabrication of Super-Oil-Repellent Dual Pillar Surfaces with Optimized Pillar Intervals

  Takashi Fujii, Yoshitaka Aoki, Hiroki Habazaki

  LANGMUIR 27 19 11752 - 11756 2011年10月 [査読有り][通常論文]
   

  Hierarchical dual pillar surfaces with optimized pillar intervals are fabricated by a novel combined process of the c oblique angle magnetron sputtering deposition of Al-Nb alloys and their anodizing. The pillar intervals are controlled by the deposition angle and cell size of a scalloped substrate for oblique angle deposition. Anodizing of the deposited pillar surfaces develops a nanopillar oxide layer, producing the hierarchical dual pillar surfaces. After being coated with a fluoroalkyl phosphate layer to reduce the surface free energy, hierarchical surfaces with submicrometer pillar intervals greater than 400 nm show super liquid repellency even for hexadecane with a low surface tension of 27.5 mN m(-1), although the submicrometer pillar surfaces with smaller submicrometer pillar intervals and without nanopillars were not super-oil-repellent. In contrast, the dual pillar surfaces show superhydrophobicity regardless of the submicrometer pillar intervals. Thus, the present study demonstrates the importance of the pillar intervals (gap size between pillars) to realize the superoleophobicity.
• Urethral Sensations are Related to the Development of Detrusor Overactivity

  Osamu Yokoyama, Yoshiji Miwa, Nobuyuki Oyama, Yoshitaka Aoki, Hideaki Ito, Kazuya Tanase, Hirokazu Ishida, Yosuke Matsuta, Naoya Kusukawa, Hiroki Yamauchi, Noriko Takahara, Nozomu Watanabe, Katsuki Tsuchiyama, Satoshi Yokoi, Hironobu Akino

  LUTS-LOWER URINARY TRACT SYMPTOMS 3 2 59 - 63 2011年09月 

  Urgency is the core symptom of the overactive bladder symptom complex, but the underlying mechanisms are not fully understood. Clinical findings have led to the assumption that bladder outlet obstruction (BOO) caused by benign prostatic enlargement (BPE) induces storage symptoms and detrusor overactivity. Presumably, BOO by BPE accounts for urgency; however, urgency is not always caused by BOO. Sensory nerves in the wall of the urethra fire in response to urethral fluid flow, and this activity initiates bladder contractions in the quiescent bladder and augments ongoing contractions in the active bladder. In humans, prostatic urethral anesthesia results in significant increases in bladder capacity among BPH patients without neurological diseases, therefore sensory stimuli from an anatomically altered prostatic urethra has the possibility to induce urgency and detrusor overactivity. Studies in animals demonstrate the basis for an excitatory urethra to bladder reflex. Urethral stimulation by prostaglandin E(2) induces an excitatory effect on micturition reflex by activation of C-fiber afferent nerves. alpha(1A)-adrenoceptor blocker has an inhibitory effect on the micturition reflex, suggesting excitatory urethra to bladder reflex is mediated by alpha(1A)-adrenoceptor. Even if there is no obstruction, increase in urethral sensory due to BPE may induce the development of the detrusor overactivity.
• Control of morphology and surface wettability of anodic niobium oxide microcones formed in hot phosphate-glycerol electrolytes

  Shu Yang, Hiroki Habazaki, Takashi Fujii, Yoshitaka Aoki, Peter Skeldon, George E. Thompson

  ELECTROCHIMICA ACTA 56 22 7446 - 7453 2011年09月 [査読有り][通常論文]
   

  We report the fabrication of superhydrophobic surfaces with a hierarchical morphology by self-organized anodizing process. Simply by anodizing of niobium metal in hot phosphate-glycerol electrolyte, niobium oxide microcones, consisting of highly branched oxide nanofibers, develop on the surface. The size of the microcones and their tip angles are controlled by changing the applied potential difference in anodizing and the water content in the electrolyte. Reduction of the water content increases the size of the microcones, with the nanofibers changing to nanoparticles. The size of microcones is also reduced by increasing the applied potential difference, without influencing the tip angle. The hierarchical oxide surfaces are superhydrophilic, with static contact angles close to 0 degrees. Coating of the anodic oxide films with a monolayer of fluoroalkyl phosphate makes the surfaces superhydrophobic with a contact angle for water as high as 175 degrees and a very small contact angle hysteresis of only 2 degrees. The present results indicate that the larger microcones with smaller tip angles show the higher contact angle for water. (C) 2011 Elsevier Ltd. All rights reserved.
• Effect of electrolyte temperature on the formation of self-organized anodic niobium oxide microcones in hot phosphate-glycerol electrolyte

  S. Yang, Y. Aoki, H. Habazaki

  APPLIED SURFACE SCIENCE 257 19 8190 - 8195 2011年07月 [査読有り][通常論文]
   

  Nanoporous niobium oxide films with microcone-type surface morphology were formed by anodizing at 10 V in glycerol electrolyte containing 0.6 mol dm(-3) K(2)HPO(4) and 0.2 mol dm(-3) K(3)PO(4) in a temperature range of 428-453 K. The microcones appeared after prolonged anodizing, but the required time was largely reduced by increasing electrolyte temperature. The anodic oxide was initially amorphous at all temperatures, but crystalline oxide nucleated during anodizing. The anodic oxide microcones, which were crystalline, appeared on surface as a consequence of preferential chemical dissolution of initially formed amorphous oxide. The chemical dissolution of an initially formed amorphous layer was accelerated by increasing the electrolyte temperature, with negligible influence of the temperature on the morphology of microcones up to 448 K. (C) 2011 Elsevier B. V. All rights reserved.
• Superhydrophobic hierarchical surfaces fabricated by anodizing of oblique angle deposited Al-Nb alloy columnar films

  Takashi Fujii, Yoshitaka Aoki, Hiroki Habazaki

  APPLIED SURFACE SCIENCE 257 19 8282 - 8288 2011年07月 [査読有り][通常論文]
   

  A combined process of oblique angle magnetron sputtering and anodizing has been developed to tailor superhydrophobic surfaces with hierarchical morphology. Isolated submicron columns of single-phase Al-Nb alloys are deposited by magnetron sputtering at several oblique deposition angles on a scalloped substrate surface, with the gaps between columns increasing with an increase in the deposition angle from 70 degrees to 110 degrees. Then, the columnar films have been anodized in hot phosphate-glycerol electrolyte to form a nanoporous anodic oxide layer on each column. Such surfaces with submicron-/nano-porous structure have been coated with a fluoroalkyl phosphate layer to reduce the surface energy. The porous surface before coating is superhydrophilic with a contact angle for water is less than 10 degrees, while after coating the contact angles are larger than 150 degrees, being superhydrophobic. The beneficial effect of dual-scale porosity to enhance the water repellency is found from the comparison of the contact angles of the submicron columnar films with and without nanoporous oxide layers. The larger submicron gaps between columns are also preferable to increase the water repellency. (C) 2011 Elsevier B. V. All rights reserved.
• Dielectric properties of anodic films on sputter-deposited Ti-Si porous columnar films

  M. Tauseef Tanvir, T. Fujii, Y. Aoki, K. Fushimi, H. Habazaki

  APPLIED SURFACE SCIENCE 257 19 8295 - 8300 2011年07月 [査読有り][通常論文]
   

  For electrolytic capacitor application of the single-phase Ti alloys containing supersaturated silicon, which form anodic oxide films with superior dielectric properties, porous Ti-7 at% Si columnar films, as well as Ti columnar films, have been prepared by oblique angle magnetron sputtering on to aluminum substrate with a concave cell structure to enhance the surface area and hence capacitance. The deposited films of both Ti and Ti-7 at% Si have isolated columnar morphology with each column revealing nanogranular texture. The distances between columns are similar to 500 nm, corresponding to the cell size of the textured substrate and the gaps between columns are 100-200 nm. When the porous Ti-7 at% Si film is anodized at a constant current density in ammonium pentaborate electrolyte, the growth of a uniform amorphous oxide film continues to similar to 35 V, while it is limited to less than 6 V on the porous Ti film. The maximum voltage of the growth of uniform amorphous oxide films on the Ti-7 at% Si films is similar for both the flat and porous columnar films, suggesting little influence of surface roughness on the amorphous-to-crystalline transition of growing anodic oxide under the high electric field. Due to the suppression of crystallization to sufficiently high voltages, the anodic oxide films formed on the porous Ti-7 at% Si film shows markedly improved dielectric properties, in comparison with those on the porous Ti film. (C) 2011 Elsevier B. V. All rights reserved.
• Enhanced capacitance of composite anodic ZrO₂ films comprising high permittivity oxide nanocrystals and highly resistive amorphous oxide matrix.

  Habazaki H, Koyama S, Aoki Y, Sakaguchi N, Nagata S

  ACS applied materials & interfaces 3 7 2665 - 2670 7 2011年07月 [査読有り][通常論文]
   

  Anodic oxide films with nanocrystalline tetragonal ZrO2 precipitated in an amorphous oxide matrix were formed on Zr-Si and Zr-Al alloys and had significantly enhanced capacitance in comparison with those formed on zirconium metal. The capacitance enhancement was associated with the formation of a high-temperature stable tetragonal ZrO2 phase with high relative permittivity as well as increased ionic resistivity, which reduces the thickness of anodic oxide films at a certain formation voltage. However, there is a general empirical trend that single-phase materials with higher permittivity have lower ionic resistivity. This study presents a novel material design based on a nanocrystalline-amorphous composite anodic oxide film for capacitor applications.
• Antimuscarinics Suppress Adenosine Triphosphate and Prostaglandin E2 Release From Urothelium With Potential Improvement in Detrusor Overactivity in Rats With Cerebral Infarction

  Osamu Yokoyama, Ippei Tanaka, Naoya Kusukawa, Hiroki Yamauchi, Hideaki Ito, Yoshitaka Aoki, Nobuyuki Oyama, Yoshiji Miwa, Hironobu Akino

  JOURNAL OF UROLOGY 185 6 2392 - 2397 2011年06月 

  Purpose: Antimuscarinics improve detrusor overactivity. We evaluated the effects and action mechanisms of imidafenacin (Kyorin Pharmaceutical, Tokyo, Japan), a novel therapeutic agent for overactive bladder with antimuscarinic activity, on mediator release from urothelium and detrusor overactivity induced by cerebral infarction.Materials and Methods: Bladder hydrodistention was achieved by intravesical infusion of Krebs solution. Bladder adenosine triphosphate and prostaglandin E-2 were measured in the presence and absence of anticholinergics using luciferin-uciferase assay and enzyme-linked immunoassay, respectively. Cerebral infarction was induced in rats by occluding the left middle cerebral artery. The effects of intravenous imidafenacin on bladder function were examined using cystometry in rats with cerebral infarction and in those pretreated with resiniferatoxin.Results: Increased intravesical adenosine triphosphate and prostaglandin E-2 were shown by induced distention of isolated rat bladders. Imidafenacin and darifenacin (Kemprotec, Middlesbrough, United Kingdom) significantly suppressed the increases in adenosine triphosphate and prostaglandin E-2. Decreased bladder capacity was observed in rats with cerebral infarction. Detrusor overactivity was suppressed with a minimum intravenous dose of 0.001 mg/kg imidafenacin. The effects of imidafenacin were not noted in rats pretreated with resiniferatoxin.Conclusions: Results support the hypothesis or suggest that imidafenacin improves cerebral infarction induced detrusor overactivity by suppressing peripheral C-fibers. This effect is thought to be associated with suppression of the release of adenosine triphosphate and prostaglandin E-2 from the urothelium.
• Two-step plasma electrolytic oxidation of Ti-15V-3Al-3Cr-3Sn for wear-resistant and adhesive coating

  S. Tsunekawa, Y. Aoki, H. Habazaki

  SURFACE & COATINGS TECHNOLOGY 205 19 4732 - 4740 2011年06月 [査読有り][通常論文]
   

  Ti-15V-3Al-3Cr-35n (Ti-15-3) is one of the important practical titanium alloys with high cold deformability and high mechanical strength, but its wear resistance is poor. This paper reports the formation of wear-resistant and adhesive ceramic coatings on Ti-15-3 by two-step plasma electrolytic oxidation (PEO). The PEO of Ti-15-3 has been carried out first in alkaline aluminate electrolyte to form a wear-resistant oxide layer and then in acid electrolyte containing both phosphoric acid and sulfuric acid to improve adhesion of the coating. The coating formed in the alkaline aluminate electrolyte is more than 10 mu m thick, and highly crystalline. The main phase is Al(2)TiO(5). This coating shows high wear resistance, but is not adherent to substrate due to the development of a number of voids and pores in the oxide layer close to the substrate. A new oxide layer with amorphous structure is formed next to the substrate in the subsequent PEO in the acid electrolyte, during which the voids are filled with a new oxide formed in the acid electrolyte, reducing the porosity. As a consequence, the adhesion of the coating is markedly improved without deteriorating the high wear resistance. (C) 2011 Elsevier B.V. All rights reserved.
• Power-law scaling of proton conductivity in amorphous silicate thin films

  Yoshitaka Aoki, Hiroki Habazaki, Toyoki Kunitake

  SOLID STATE IONICS 192 1 93 - 96 2011年06月 [査読有り][通常論文]
   

  Amorphous hafnium silicate, a-Hf0.1Si0.9Ox, thin film with thickness of 32, 41, 55, 80, 110, 120, 180 and 320 nm was prepared by multiple spin-cast process and the proton conductivity across the films was measured at intermediate temperatures (100-400 degrees C) in dry atmosphere. The morphologically- and compositionally-uniform films were prepared on a substrate as confirmed by SEM. RBS and XPS measurements. a-Hf0.1Si0.9Ox thin film clearly revealed the H/D isotope effect on ionic conductivity, indicating that protonic conduction is dominant in the measured temperature range. The films did not reveal thickness-dependent proton conductivity in dry air and the sigma at given temperatures is almost constant at any thickness. No increment of sigma in a-Hf0.1Si0.9Ox thin films by reduction of thickness might be related to the absence of the highly-conductive acid network with mesoscopically-sized length because of the relatively low concentration of Bronsted acid sites inside films. (C) 2010 Elsevier B.V. All rights reserved.
• Dielectric breakdown and healing of anodic oxide films on aluminium under single pulse anodizing

  Santosh Prasad Sah, Yasuhiro Tatsuno, Yoshitaka Aoki, Hiroki Habazaki

  CORROSION SCIENCE 53 5 1838 - 1844 2011年05月 [査読有り][通常論文]
   

  Single pulse anodizing of aluminium micro-electrode has been employed to study the behaviour of dielectric breakdown and subsequent oxide formation on aluminium in alkaline silicate and pentaborate electrolytes. Current transients during applying pulse voltage have been measured, and surface has been observed by scanning electron microscopy. Two types of current transients are observed, depending on the electrolyte and applied voltage. There is a good correlation between the current transient behaviour and the shape of discharge channels. In alkaline silicate electrolyte, circular open pores are healed by increasing the pulse width, but such healing is not obvious in pentaborate electrolyte. (C) 2011 Elsevier Ltd. All rights reserved.
• alpha(1)-Adrenoceptor blocker naftopidil improves sleep disturbance with reduction in nocturnal urine volume

  Osamu Yokoyama, Yoshitaka Aoki, Akira Tsujimura, Tetsuya Takao, Mikio Namiki, Akihiko Okuyama

  WORLD JOURNAL OF UROLOGY 29 2 233 - 238 2011年04月 

  To examine the mechanism underlying improvements in nocturia by alpha(1)-blockers, we investigated whether the alpha(1)-blocker naftopidil acts on nocturia with sleep disturbance using a frequency/volume chart (FVC).A total of 56 male patients with lower urinary tract symptoms were enrolled. The inclusion criteria were as follows: eight or more points on the I-PSS; three or more points on the I-PSS score for nocturia; and prostate volume larger than 20 ml. Patients received 50 mg of naftopidil once daily for 4 weeks, and non-responders received 75 mg for another 4 weeks. All patients were examined, and their data entered into FVC for 2 days before and after administration of naftopidil. Quality of sleep was also evaluated using modified Pittsburgh sleep quality index (PSQI).Patients with sleep quality scores of three or four were assigned to sleep disturbance group (n = 33), while those with scores of less than three were assigned to non-disturbance group (n = 23). After administration of naftopidil, total I-PSS decreased and nocturia score decreased from 3.5 to 2.6 (P < 0.01). Total mean score of modified PSQI in sleep disturbance group became significantly lower after administration of naftopidil (from 16.9 to 14.0; P < 0.01). Naftopidil significantly decreased nocturnal urine volume, resulting in a decrease in the nocturnal polyuria index in both sleep disturbance and non-disturbance groups.These results suggest that alpha(1)-blockers have the ability to normalize sleep disorders. Naftopidil improved nocturnal polyuria regardless of the presence of sleep disturbance, meaning that it might directly reduce nocturnal urine production.
• Growth of porous anodic alumina films in hot phosphate-glycerol electrolyte

  S. Yang, Y. Aoki, P. Skeldon, G. E. Thompson, H. Habazaki

  JOURNAL OF SOLID STATE ELECTROCHEMISTRY 15 4 689 - 696 2011年04月 [査読有り][通常論文]
   

  Growth of porous anodic alumina films has been examined at 10 V in hot phosphate-containing glycerol electrolyte containing 0.1 to 0.57 mass% water. The growth rate of the films is highly dependent upon the water content of the electrolyte, reducing markedly at a water content of 0.1 mass%, an opposite trend to that found previously for the formation of porous films on titanium and niobium. Chemical dissolution of the anodic alumina is also suppressed in electrolyte of low water content. GDOES depth profiles revealed that an increased water content of the electrolyte promoted the incorporation of phosphorus species into the films, although chemical dissolution reduced the amounts of phosphorus in the outer regions. Carbon species also appeared to be present in films, particularly at lower water content. Using a niobium oxide outer layer to suppress chemical dissolution resulted in films that were about 1.2 times the thickness of the consumed aluminium for an electrolyte containing 0.25 mass% water. The expansion suggests a possible contribution of field-assisted flow of film material in the growth of the porous anodic film.
• Finite Size Effect of Proton-Conductivity of Amorphous Silicate Thin Films Based on Mesoscopic Fluctuation of Glass Network

  Yoshitaka Aoki, Hiroki Habazaki, Shinji Nagata, Aiko Nakao, Toyoki Kunitake, Shu Yamaguchi

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 10 3471 - 3479 2011年03月 [査読有り][通常論文]
   

  The finite size effect of proton conductivity of amorphous silicate thin films, a-M0.1Si0.9Ox (M = Al, Ga, Hf, Ti, Ta, and La), was investigated. The proton conductivity across films, sigma, was measured in dry air by changing the thickness in the range of 10-1000 nm. sigma of the films with M = Al, Ga, and Ta was elevated in a power law by decreasing thickness into less than a few hundred nanometers, and the increment was saturated at a thickness of several 10's of nanometers. On the other hand, a of the films with M = Hf, Ti, and La was not related to the decrease of the thickness in the range of >10 nm. Thickness-dependent conductivity of the former could be numerically simulated by a percolative resistor network model that involves the randomly distributed 3 4 5 6 7 8 2 3 4 5 6 7 8 array of two kinds of resistors R-1 and R-2 (R-1 > R-2) in the form of a simple cubic-type lattice. High-resolution TEM clarified that a-M0.1Si0.9Ox films involved heterogeneous microstructures made of the condensed domain and the surrounding uncondensed matrix due to the fluctuation of glass networks on the nanometer scale. The condensed domain had a wormlike shape with an average length of several 10's of nanometers and performed the role of the proton conduction pathway penetrating through the poorly conducting matrix. It was concluded that the thickness-dependent conductivity could be identical to finite-size scaling of the percolative network of the interconnected domains in the nanometer range.
• Improved Thermal Stability of Efficient Proton-Conducting Anodic ZrO2-WO3 Nanofilms by Incorporation of Silicon Species

  Ke Ye, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 158 11 C385 - C390 2011年 [査読有り][通常論文]
   

  Novel proton-conducting amorphous anodic ZrO2-WO3-SiO2 films, 200 nm thick, are prepared by anodizing of sputter-deposited Zr37W47Si16 at 100 V with current decay for 1.8 ks in 0.1 mol dm(-3) phosphoric acid electrolyte at 20 degrees C. The resultant anodic films have been characterized using electrochemical impedance spectroscopy, transmission electron microscopy, glow discharge optical emission spectroscopy and Rutherford backscattering spectroscopy. The addition of silicon species to the anodic ZrO2-WO3 film significantly enhanced the thermal stability. Even after thermal treatment at 300 degrees C in dry Ar atmosphere, the anodic ZrO2-WO3-SiO2 films revealed stable proton conductivity in the temperature range of 50-225 degrees C, while the anodic ZrO2-WO3 on the Zr43W57 loses the proton conductivity by annealing at 250 degrees C. The anodic film on the Zr37W47Si16 consisted of two layers, comprising an outer thin ZrO2 layer, free from tungsten and silicon species, and an inner main layer containing all zirconium, tungsten and silicon species. The results in this study suggest that the conductivity deterioration at high annealing temperatures is associated with the diffusion-induced formation of a poorly-conducting layer near the alloy/anodic oxide interface. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.068111jes] All rights reserved.
• Proton-Conductivity of Amorphous Aluminum Phosphate Thin Films under Anhydrous Conditions

  Y. Aoki, S. Hirata, H. Habazaki

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 158 4 P41 - P44 2011年 [査読有り][通常論文]
   

  The proton conductivity sigma across 100 nm thick, amorphous aluminum phosphate thin films under anhydrous conditions was investigated. The densely packed glass films were uniformly formed without formation of pinholes and clacks over the electrode substrate by multiple spin-coating with a mixed precursor sol, as checked by transmission electron microscopy. X-ray absorption spectroscopy, and Fourier transform infrared indicated that the Al-rich films were mainly composed of alumina and phosphate mixed glass phase, but the P-rich films involved a large amount of the aluminum metaphosphate glass moiety. sigma abruptly changed with Al/P ratio owing to this variation of glass network structure. The Al-rich films revealed the large activation energy E-a of about 1.0 eV, but the P-rich films revealed the small E-a of about 0.2 eV above 200 degrees C and they kept the value on the order of 10(-5) S cm(-1) at the temperatures. Consequently, the sigma of P-rich films were one order of magnitude higher than that of the others at around 300 degrees C. (C) 2011 Electrochemical Society. [DOI: 10.1149/1.3551572] All rights reserved.
• Thin Film Fuel Cell Based on Nanometer-Thick Membrane of Amorphous Zirconium Phosphate Electrolyte

  Y. Aoki, Y. Fukunaga, H. Habazaki, T. Kunitake

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 158 8 B866 - B870 2011年 [査読有り][通常論文]
   

  Novel thin film fuel cell based on the 100 nm-thick electrolyte of amorphous ZrP(2.6)O(x), working at 400 degrees C, was demonstrated. The hydrogen permeable membrane fuel cell (HMFC) using a Pd foil as a nonporous solid anode was fabricated. Ni interlayer of several hundreds nm thickness was introduced between the Pd anode and the ZrP(2.6)O(x) electrolyte in order to suppress the deterioration of the electrolyte nanofilm by the deformation of the Pd anode during hydrogen absorption. In the ZrP(2.6)O(x) electrolyte the transport number of proton was unity at 400 degrees C as determined by an EMF measurement. The modification of the Ni anode surface by an ultrathin Pt or Pd layer effectively decreased the anode/electrolyte interfacial polarization. Consequently, the HMFC revealed the OCV of 1.0 V and the maximum power density of 1.8 mW cm(-2) at 400 degrees C. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3595388] All rights reserved.
• Galvanostatic Growth of Nanoporous Anodic Films on Iron in Ammonium Fluoride-Ethylene Glycol Electrolytes with Different Water Contents

  Hiroki Habazaki, Yoshiki Konno, Yoshitaka Aoki, Peter Skeldon, George E. Thompson

  JOURNAL OF PHYSICAL CHEMISTRY C 114 44 18853 - 18859 2010年11月 [査読有り][通常論文]
   

  The growth of porous anodic films on iron has been examined at a constant current density of 50 A m(-2) in 0.1 mol L(-1) NH(4)F-elhylene glycol electrolytes containing 0.1-1.5 mol L(-1) water. Nanoporous films are formed in all the electrolytes, with the growth rate increasing with the decrease in the water content of the electrolyte. A barrier layer, in which a high electric field is applied during anodizing, thickens in proportion to the formation voltage at a ratio of 1.9 nm V(-1), regardless of the water content of the electrolyte. However. there is a transition water content between 0.3 and 0.5 mol L(-1). at which growth behavior changes. Above the transition level, the formation voltage is constant after an initial voltage rise, with the constant voltage slightly rising with a decrease in water content. In contrast, the formation voltage increases continuously to more than 150 V when the water contents are below the transition level. The anodic films are poorly crystalline and contain a significant amount of fluoride species. A high enrichment of fluoride species occurs near the metal/film interface when the water content in the electrolyte is below the transition level. Such enrichment is not as significant, or possibly absent, in electrolytes of increased water content.
• Selective alpha(1A)-blocker improves bladder storage function in rats via suppression of C-fiber afferent activity

  Osamu Yokoyama, Hideaki Ito, Yoshitaka Aoki, Nobuyuki Oyama, Yoshiji Miwa, Hironobu Akino

  WORLD JOURNAL OF UROLOGY 28 5 609 - 614 2010年10月 

  In the present study, we used animal models to investigate whether the selective alpha(1A)-blocker silodosin exerts inhibitory effects on detrusor overactivity by modulating C-fiber afferent activity.To desensitize C-fiber afferents, 0.3 mg/kg of resiniferatoxin (RTX) was subcutaneously injected into some female Sprague-Dawley rats 2 days before creation of each model. (1) Left middle cerebral artery occlusion was performed to create a cerebral infarction (CI) model (CI rats). The effects of intravenous (i.v.) and intrathecal (i.t.) administrations of silodosin on cystometrography parameters were evaluated in conscious rats. (2) Rhythmic bladder pressure was recorded in rats under urethane anesthesia. Prostaglandin (PG) E-2 (0.4 mg/mL) was continuously administered intraurethrally, and the effects of intra-arterial (i.a.) silodosin on the micturition reflex (MR) were investigated.(1) Silodosin (i.v.) dose-dependently increased bladder capacity (BC) in CI rats without decreasing bladder contraction pressure, but had no effects on BC in RTX-CI rats. Silodosin (i.t.) markedly increased BC in CI rats, but not in RTX-CI rats. (2) After intraurethral administration of PGE(2), the bladder contraction interval (BCI) was markedly reduced in non-RTX rats, but unchanged in RTX rats. Silodosin (i.a.) significantly prolonged BCI in non-RTX rats receiving intraurethral PGE(2).These results suggest that the alpha(1A)-AR subtype activates C-fiber afferents, and that consequently alpha(1A)-blockade can improve bladder storage function.
• Thickness-Induced Proton-Conductivity Transition in Amorphous Zirconium Phosphate Thin Films

  Yoshitaka Aoki, Kota Ogawa, Hiroki Habazaki, Toyoki Kunitake, Yuanzhi Li, Shinji Nagata, Shu Yamaguchi

  CHEMISTRY OF MATERIALS 22 19 5528 - 5536 2010年10月 [査読有り][通常論文]
   

  Amorphous zirconium phosphate thin films, a-ZrP2.5Ox, revealed unique proton conductivity transition induced by reducing thickness due to the formation of highly conductive, hydrated nanolayer. The dense films made of a metaphosphate glass phase were uniformly formed over the electrode substrate by multiple spin-coating with a mixed precursor sol. as checked by TEM and RBS. When thickness d was larger than 60 nm, the proton conductivity across film and the activation energy E were not variable with d. sigma abruptly increased 200 times and E-a decreases from 0,9 to 0.7 eV when d decreased from 60 to 40 nm. and it became thickness-independent again in d < 40 nm. a of 100 mm-thick film is increased to the similar value as that of the 40 nm thick by annealing at 400 degrees C in H2O/air. It was concluded that the conductivity transition could be associated with the hydration of metaphosphate nanolayer. The hydrated. high-conductive phase was very stable Only when the thickness was less than 100 nm. Therefore, the films of more than hundreds nm thickness cannot change to the high-conducting hydrated phase throughout the film thickness. These unprecedented behaviors could not be explicable with a simple model based on the core space charge or continuum structural relaxation at hetrointerface.
• Controlled morphology of aluminum alloy nanopillar films: from nanohorns to nanoplates

  Takashi Fujii, Yoshitaka Aoki, Koji Fushimi, Takeshi Makino, Shoji Ono, Hiroki Habazaki

  NANOTECHNOLOGY 21 39 395302  2010年10月 [査読有り][通常論文]
   

  Nanopillar films of Al-Nb alloys have been fabricated on substrates with a regular concave cell structure by oblique angle physical vapor deposition. The concave cell structure of the substrate increases the shadow region for the flux of depositing atoms, assisting the formation of an isolated nanopillar on each cell. Depending upon the alloy composition and deposition angle, the pillar shape changes from horn-like nanopillars through triangular nanoprisms to nanoplates. The Al-Nb alloy nanoplate films with wide gaps between plates are of interest as electrodes for capacitor applications. The dielectric oxide film formed on the nanoplate film showed a capacitance more than ten times larger than that on the respective flat film, due to the enlarged surface area.
• Formation of porous anodic titanium oxide films in hot phosphate/glycerol electrolyte

  H. Habazaki, M. Teraoka, Y. Aoki, P. Skeldon, G. E. Thompson

  ELECTROCHIMICA ACTA 55 12 3939 - 3943 2010年04月 [査読有り][通常論文]
   

  The present study reveals the formation of porous anodic films on titanium at an increased growth rate in hot phosphate/glycerol electrolyte by reducing the water content. A porous titanium oxide film of 12 mu m thickness, with a relatively low content of phosphorus species, is developed after anodizing at 5 V for 3.6 ks in 0.6 mol dm(-3) K(2)HPO(4) +0.2 mol dm(-3) K(3)PO(4)/glycerol electrolyte containing only 0.04% water at 433K. The growth efficiency is reduced by increasing the formation voltage to 20V, due to formation of crystalline oxide, which induces gas generation during anodizing. The film formed at 20V consists of two layers, with an increased concentration of phosphorus species in the inner layer. The outer layer, comprising approximately 25% of the film thickness, is developed at low formation voltages, of less than 10 V, during the initial anodizing at a constant current density of 250 A m(-2). The pore diameter is not significantly dependent upon the formation voltage, being similar to 10 nm. (C) 2010 Elsevier Ltd. All rights reserved.
• Amorphous-to-crystalline transition of silicon-incorporated anodic ZrO2 and improved dielectric properties

  S. Koyama, Y. Aoki, S. Nagata, H. Kimura, H. Habazaki

  ELECTROCHIMICA ACTA 55 9 3144 - 3151 2010年03月 [査読有り][通常論文]
   

  Sputter-deposited zirconium and Zr-16 at.% Si alloy have been anodized to various voltages at several formation voltages in 0.1 mol dm(-3) ammonium pentaborate electrolyte at 298 K for 900 s. The resultant anodic films have been characterized using X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy, and electrochemical impedance spectroscopy. The anodic oxide films formed on Zr-16 at.% Si are amorphous up to 30 V, but the outer part of the anodic oxide films crystallizes at higher formation voltages. This is in contrast to the case of sputter-deposited zirconium, on which the crystalline anodic oxide films, composed mainly of monoclinic ZrO2, are developed even at low formation voltages. The outer crystalline layer on the Zr-16 at.% Si consists of a high-temperature stable tetragonal phase of ZrO2. Due to immobile nature of silicon species, silicon-free outermost layer is formed by simultaneous migrations of Zr4+ ions outwards and O2- ions inwards. An intermediate crystalline oxide layer, in which silicon content is lower in comparison with that in the innermost layer, is developed at the boundary of the crystalline layer and amorphous layer. Capacitances of the anodic zirconium oxide are highly enhanced by incorporation of silicon due to reduced film thickness, even though the permittivity of anodic oxide decreases with silicon incorporation. (C) 2010 Elsevier Ltd. All rights reserved.
• Ion-conducting, sub-100 nm-thick film of amorphous hafnium silicate

  Yoshitak Aoki, Hiroki Habazaki, Toyoki Kunitake

  SOLID STATE IONICS 181 3-4 115 - 121 2010年02月 [査読有り][通常論文]
   

  Ceramic electrolytes operating in the temperature range of 200 to 500 degrees C under dry atmosphere are a key material for the next-generation fuel cell and related applications. We discovered that nanometer-thick films of amorphous hafnium silicate (Hf(n)Si(1-n)O(x)) exhibited efficient ionic conduction at 100-400 degrees C in dry air. When the fraction of hafnium doping was around 0.1, the nanofilm showed a low area-specific-resistance (<0.15 Omega cm(2)) at around 350 degrees C that was small enough for the practical fuel cell application. The sub-100 nm-thick membranes of Hf(0.13)Si(0.87)O(x), could be fabricated on porous Pt/alumina substrate to provide gas concentration cells. The electromotive force observed with H(2) concentration cell indicated that the ceramic nanomembrane acted as predominant proton conductor without permeation of H(2) gas. In addition, the Hf(0.13)Si(0.87)O(x) and Zr(0.11)Si(0.89)O(x) membranes responded to the change of O(2) pressures in O(2) concentration cells, while the Al(0.16)Si(0.84)O(x) and Ce(0.06)Si(0.94)O(x) membranes did not produce the electrical voltage by gradient of O(2) pressure. We conclude that Hf(0.13)Si(0.87)O(x) nanomembrane is promising as electrolyte material for fuel cells and related ionics devices. (C) 2009 Published by Elsevier B.V.
• Influence of Phosphate Concentration on Plasma Electrolytic Oxidation of AZ80 Magnesium Alloy in Alkaline Aluminate Solution

  Santosh Prasad Sah, Yoshitaka Aoki, Hiroki Habazaki

  MATERIALS TRANSACTIONS 51 1 94 - 102 2010年01月 [査読有り][通常論文]
   

  Plasma electrolytic oxidation of AZ80 magnesium alloy in alkaline aluminate electrolytes develops MgAl2O4-based highly crystalline oxide coatings with the morphology changing largely with phosphate concentration in electrolyte. The thickness of the coatings increases with phosphate concentration from 5 mu m in phosphate-free electrolyte to similar to 70 mu m in the electrolyte containing 0.1 mol.dm(-3) phosphate after anodizing for 900 s. The formation of the latter thick coating is associated with intense sparking during, anodizing. The thick coatings formed in the electrolytes containing 0.075 and 0.1 mol.dm(-3) phosphate are highly cracked. In contrast, the coating formed in the electrolyte containing 0.05 mol.dm(-3) phosphate is relatively uniform, showing the highest corrosion protection in 0.5 mol.dm(-3) NaCl solution. The coatings consist of two layers, comprising an outer thick layer with high concentration of aluminum and an inner thin magnesium-rich layer. [doi:10.2320/matertrans.M2009226]
• Intermediate-Temperature, Proton-Conducting Membranes of Hafnium Phosphate and Zirconium Phosphate/Borate/Sulfate

  Yuanzhi Li, Emi Muto, Yoshitaka Aoki, Toyoki Kunitake

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 157 8 B1103 - B1108 2010年 [査読有り][通常論文]
   

  Uniform, defect-free nanofilms (around 100 nm thick) of hafnium phosphate were prepared via layer-by-layer deposition of precursor solution of metal alkoxides and were shown to give practically useful proton conductivity at 300-400 degrees C as fuel cell electrolyte membrane. Annealing of the deposited precursor film at 500 degrees C gave a lower area specific resistance (R(AS)) than that at 400 degrees C, and this effect was coincident with the formation of the pyrophosphate unit. The best (lowest) R(AS) value of less than 0.1 Omega cm(2) for hafnium phosphate membrane (annealing at 500 degrees C, 291 nm thick, conductivity of 3 x 10(-4) S cm(-1) at 320 degrees C) was comparable to that of a nanofilm of an yttrium-doped zirconium phosphate. The RAS values of nanofilms of zirconium sulfate and zirconium borate were 2-3 orders higher than that of the corresponding zirconium phosphate. It is clear from these results that nanofilms of various solid acids are promising candidates for the electrolyte membrane of fuel cells operating at the intermediate temperatures of 300-400 degrees C. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3432600] All rights reserved.
• Phase Transformation and Capacitance Enhancement of Anodic ZrO2-SiO2

  S. Koyama, Y. Aoki, N. Sakaguchi, S. Nagata, H. Habazaki

  JOURNAL OF THE ELECTROCHEMICAL SOCIETY 157 12 C444 - C451 2010年 [査読有り][通常論文]
   

  Capacitance enhancement of anodic oxide films on zirconium by adding silicon is reported here with correlation to the phase transformation of the oxide. The anodic oxide film formed on zirconium consists mainly of monoclinic ZrO2, which changes to tetragonal ZrO2 phase on the Zr-5.5 atom % Si. Further increase in the silicon contents to 10 and 16 atom % results in the formation of amorphous oxide up to 30 V, above which two-layered films, comprising an outer crystalline tetragonal-phase oxide layer and an inner amorphous layer, are developed. The relative thickness of the outer crystalline layer to the total film thickness increases with formation voltage. The highest capacitance of the anodic oxide films is obtained on the Zr-10 atom % Si. The changes in capacitance, permittivity and formation ratio of anodic oxide films with alloy composition are discussed with phase transformation and growth process of anodic oxides. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3503592] All rights reserved.
• Formation of porous niobium films by oblique angle deposition: Influence of substrate morphology

  M. Tauseef Tanvir, Y. Aoki, H. Habazaki

  THIN SOLID FILMS 517 24 6711 - 6716 2009年10月 [査読有り][通常論文]
   

  The present work demonstrates the formation of porous niobium films with separated columnar structures by oblique angle magnetron sputtering for capacitor application. The mobium films deposited on textured aluminium substrates, which had concave cell structures with the cell sizes ranging from 125 nm to 550 nm, consist of isolated columns of niobium with wider gaps between columns developing on the substrates with larger cell sizes. The surface areas of the deposited films. evaluated by the capacitance of the anodic films formed at several voltages, increased with an increase in the cell size of substrate. The surface area decreases with an increase in the formation potential of anodic films from 2 V to 10 V vs Ag/AgCl, because the gaps are filled with anodic oxide as a consequence of the large Pilling-Bedworth ratio of 2.6 for the Nb/Nb(2)O(5) system. The reduction of the surface area is suppressed when the substrate with larger cell size is used, due to the formation of niobium columns with wider gaps, which are not filled with anodic oxide. The high surface area even at higher formation voltages of the anodic films is a requisite for capacitor application. (C) 2009 Elsevier B.V. All rights reserved.
• Size-Scaling of Proton Conductivity in Amorphous Aluminosilicate Acid Thin Films

  Yoshitaka Aoki, Hiroki Habazaki, Toyoki Kunitake

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 40 14399 - 14406 2009年10月 [査読有り][通常論文]
   

  Amorphous aluminosilicate nanofilms, a-Al(0.1)Si(0.9)O(x), exhibit unique size-enhancement of the proton conductivity along the thickness direction because of the presence of the zeolite-like, acid site network with the mesoscopically sized dimension inside glass matrix. The dense films with the thickness of 22-1400 nm were uniformly formed over the electrode substrate in nanometer thickness precision by multiple spin-coating with a mixed precursor Sol. XANES measurements indicated that the basic framework of a-Al(0.1)Si(0.9)O(x) films was similar to the zeolitic one, consisting of the corner-linkage Of SiO(4) and AlO(4) tetrahedral units. These films revealed the complex temperature- and humidity-dependency of proton conductivity by the existence of two kinds of protonic carriers: Bronsted acidic protons and Lewis acidic protons. The Bronsted acidic protons could be persistent in amorphous films at around 500 degrees C, as checked by thermal desorption spectroscopy, so that the film exhibited the humidity-independent proton conductivity at temperatures above 300 degrees C. Furthermore, the conductivity across the film a increased in a power low by reduction of the film thickness of to less than 120 nm as sigma proportional to d-(tau), and it was saturated when the thickness become less than 40 nm. The observed scaling index tau was 2.2 in agreement with the value of the theoretical index (2.3) of cluster size scaling in a three-dimensional percolation system. This conduction behavior is explicable by finite size-scaling of the highly conductive pathway based on the interconnected Bronsted acid centers in the range of a few tens to hundreds of nanometers.
• Preparation of self-organized porous anodic niobium oxide microcones and their surface wettability

  Y. Oikawa, T. Minami, H. Mayama, K. Tsujii, K. Fushimi, Y. Aoki, P. Skeldon, G. E. Thompson, H. Habazaki

  ACTA MATERIALIA 57 13 3941 - 3946 2009年08月 [査読有り][通常論文]
   

  Porous anodic niobium oxide with a pore size of similar to 10 nm was formed at 10 V in glycerol electrolyte containing 0.6 mol dm(3) K(2)HPO(4) and 0.2 mol dm(-3) K(3)PO(4) at 433 K. After prolonged anodizing for 5.4 ks, niobium oxide microcones develop on the surface. X-ray diffraction patterns of the anodized specimens revealed that the initially formed anodic oxide is amorphous, but an amorphous-to-crystal-line transition occurs during anodizing. As a consequence of the preferential chemiccal dissolution of the initially formed amorphous oxide, due to different solubility of the amorphous and crystalline oxides, crystalline oxide microcones appear on the film surface after prolonged anodizing. The surface is superhydrophilic. After coating with fluorinated alkylsilane, the surface becomes superhydrophobic with a contact angle of 158 degrees for water. The surface is also oil repellent, with a contact angle as high as 140 degrees for salad oil. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
• Depth profile analysis of thin passive films on stainless steel by glow discharge optical emission spectroscopy

  M. Uemura, T. Yamamoto, K. Fushimi, Y. Aoki, K. Shimizu, H. Habazaki

  CORROSION SCIENCE 51 7 1554 - 1559 2009年07月 [査読有り][通常論文]
   

  Thin passive films formed on highly corrosion-resistant type-312L stainless steel, containing 20 mass% chromium and 6 mass% molybdenum, in 2 mol dm(-3) HCl solution at 293 K have been analyzed by glow discharge optical emission spectroscopy (GDOES). The stainless steel does not suffer pitting corrosion even in this aggressive solution, showing a wide passive potential region. The depth profiles obtained clearly show a two-layer structure of the air-formed and passive films: an outer iron-rich layer and an inner layer highly enriched in chromium. Alloy-constituting molybdenum is deficient in the inner layer of the passive films and is enriched in the outer layer, particularly at the active dissolution potential. The molybdenum species in the outer layer may retard the active dissolution of stainless steel, promoting the formation of stable passive films highly enriched in chromium. Chloride ions are present only at the outermost part of the passive films, not penetrating into the interior part. (C) 2008 Elsevier Ltd. All rights reserved.
• Improved electrical properties of silicon-incorporated anodic niobium oxide formed on porous Nb–Si substrate

  M. T. Tanvir, Y. Aoki, H. Habazaki

  Applied Surface Science 255 20 8383 - 8389 2009年07月 [査読有り][通常論文]
   

  In the present study, porous Nb-Si alloy films with isolated nano-column morphology have been successfully developed by oblique angle magnetron sputtering on to aluminum substrate with concave cell structure. The deposited films are amorphous with the 15 at% silicon supersaturated into niobium. The porous Nb-15 at% Si films, as well as niobium films with similar morphology, are anodized at several voltages up to 50 V in 0.1 mol dm (3) ammonium pentaborate electrolyte. Due to the presence of sufficient gaps between neighboring columns, the gaps are not filled with anodic oxide, despite the large Pilling-Bedworth ratio (for instance, 2.6 for Nb/Nb(2)O(5)) and hence, a linear correlation between the reciprocal of capacitance and formation voltage is obtained for the Nb-15 at% Si. From the comparison with the anodic films formed on porous niobium films, it has been found that silicon addition improves the thermal stability of anodic niobium oxide; the change in capacitance and increase in leakage current become small for the Nb-Si. The findings indicate the potential of oblique angle deposition to tailor porous non-equilibrium niobium alloy films for high performance niobium-base capacitor. (C) 2009 Elsevier B.V. All rights reserved.
• Electronic transport and magnetic properties of the perovskites La0.8Sr0.2Co1-xFexO3; x <= 0.3

  Jozsef Hakl, F. Peter de Chatel, Sandor Meszaros, Kalman Vad, Zoltan Klencsar, Zoltan Nemeth, Erno Kuzmann, Zoltan Homonnay, Attila Vertes, Athanassios Simopoulos, Eamonn Devlin, Yoshitaka Aoki, Hidetaka Konno, Subodh Kumar De

  SOLID STATE SCIENCES 11 4 852 - 860 2009年04月 [査読有り][通常論文]
   

  Transport and magnetic properties of LaCoO3-based compounds, doped with 20% Sr and 2.5, 5,10,15, 20 and 30% Fe, were investigated by means of magnetization, resistivity and magnetoresistance measurements as well as by Fe-57 Mossbauer spectroscopy. While the temperature dependence of the dc and ac magnetic susceptibilities reveals the presence of magnetic phase separation accompanied by spin-glass and cluster-glass behavior, the electrical resistivity and magnetoresistance characteristics indicate that the mesoscopic structure of the present compounds is rather well described as consisting of ferromagnetic, metallic grains embedded in an insulating matrix. The effect of the partial Co -> Fe substitution on the bulk magnetic and transport properties, as well as on the local state of Co and Fe ions is discussed. (C) 2009 Elsevier Masson SAS. All rights reserved.
• Importance of water content in formation of porous anodic niobium oxide films in hot phosphate-glycerol electrolyte

  H. Habazaki, Y. Oikawa, K. Fushimi, Y. Aoki, K. Shimizu, R. Skeldon, G. E. Thompson

  ELECTROCHIMICA ACTA 54 3 946 - 951 2009年01月 [査読有り][通常論文]
   

  Niobium has been anodized at a constant current density to 10 V with a current decay in 0.8 mol dm(-3) K(2)HPO(4)-glycerol electrolyte containing 0.08-0.65 mass% water at 433 K to develop porous anodic oxide films. The film growth rate is markedly increased when the water content is reduced to 0.08 mass%; a 28 mu m-thick porous film is developed in this electrolyte by anodizing for 3.6 ks, while the thickness is 4.6 and 2.6 mu m in the electrolytes containing 0.16 and 0.65 mass% water respectively. For all the electrolytes, the film thickness changes approximately linearly with the charge passed during anodizing, indicating that chemical dissolution of the developing oxide is negligible. SIMS depth profiling analysis was carried for anodic films formed in electrolyte containing similar to 0.4 mass% water with and without enrichment of H(2) (18)O. Findings disclose that water in the electrolyte is a predominant source of oxygen in the anodic oxide films. The anodic films formed in the electrolyte containing 0.65 mass% water are practically free from phosphorus species. Reduction in water content increased the incorporation of phosphorus species. (c) 2008 Elsevier Ltd. All rights reserved.
• Formation of porous aluminum films with isolated columnar structure using physical vapor deposition for medium-voltage and high-voltage capacitors

  T. Fujii, Y. Aoki, K. Fushimi, T. Makino, S. Ono, H. Habazaki

  Hyomen Gijutsu 60 3 166 - 169 2009年 [査読有り][通常論文]
  
• High Proton Conductivity in Anodic ZrO2/WO3 Nanofilms

  Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 48 41 7582 - 7585 2009年 [査読有り][通常論文]
  
• Efficient Proton-Conductivity of Gas-Tight Nanomembranes of Silica-Based Double Oxides

  Yoshitaka Aoki, Emi Muto, Aiko Nakao, Toyoki Kunitake

  ADVANCED MATERIALS 20 23 4387 - 4393 2008年12月 [査読有り][通常論文]
   

  Nanometer-thick membranes of a large variety of silica-based double oxides commonly show gas-tightness (H(2) and O(2)) and efficient proton conduction at 100-400 degrees Cunder dry atmosphere.
• Determination of Surface Area and Porosity of Small, Nanometer-Thick Films by Quartz Crystal Microbalance Measurement of Gas Adsorption

  Yoshitaka Aoki, Mineo Hashizume, Shinya Onoue, Toyoki Kunitake

  JOURNAL OF PHYSICAL CHEMISTRY B 112 46 14578 - 14582 2008年11月 [査読有り][通常論文]
   

  The Brunauer-Emmett-Teller (BET) Surface area of 15 nm-thick films made of TiO2,/polyelectrolyte bilayer was determined by quartz crystal microbalance (QCM) measurement of N-2 and Ar adsorption isotherms at 77 K. The measurements were carried out using a home-built vacuum chamber that includes built-in 9 MHz QCM and cryostat units. As little as 1 ng of the adsorbed gas could be detected, and the BET surface area of a flat Au film (ca. 0.5 cm(2)) on an oscillator was determined within an experimental error of +/- 5%. The titania/polymer composite film gives N-2 and Ar adsorption isotherms consisting of a less-pronounced type-I curve and a break at around p/p(0) = 0.7. This behavior is ascribed to the presence of irregular micropores and 6 nm (phi-mesopores in the composite film. An analysis of the isotherms shows that the porosity of the composite film is about 12%. which is much smaller than that of bulk titania (gel powder. The greater density appears to be related to the reported superior properties (robustness and resistance to electrical breakdown) of the organic/inorganic multilayer film. We conclude that the QCM-based, high-precision measurement of Gas adsorption is a powerful tool for investigation of the detailed morphology of nanometer-thick films.
• Oblique angle deposition of columnar niobium films for capacitor application

  M. Tauseef Tanvir, K. Fushimi, Y. Aoki, H. Habazaki

  MATERIALS TRANSACTIONS 49 6 1320 - 1326 2008年06月 [査読有り][通常論文]
   

  Niobium films with isolated columnar morphology have been prepared by oblique angle magnetron sputtering for capacitor application. Anodizing of the deposited mobium to form dielectric mobium oxide reduces the surface roughness, since the gaps between the neighboring columns are filled with the oxide due to large Pilling-Bedworth ratio for Nb/Nb2O5. To increase the gaps between neighboring columns, the influences of the angle of mobium flux to substrate and substrate surface roughness on the columnar morphology of the deposited films have been investigated using scanning electron microscopy and the electrochemical measurements. The deposition on the textured rough substrate surface and at higher angle of the mobium flux from normal to the substrate surface fabricates the mobium films with higher surface roughness.
• Efficient, anhydrous proton-conducting nanofilms of Y-doped zirconium pyrophosphate at intermediate temperatures

  Yuanzhi Li, Toyoki Kunitake, Yoshitaka Aoki, Emi Muto

  ADVANCED MATERIALS 20 12 2398 - + 2008年06月 [査読有り][通常論文]
   

  composition of Y(0.9)5/Y-0.05/P-2.64, exhibit high proton conductivities with an area-specific resistance of 0.085 Omega cm(2). The films are very stable, even when operating in the flow of dry air at 340 degrees C for a prolonged period of time (see figure).
• Facile fabrication of silver nanofin array via electroless plating

  Kentaro Miyoshi, Yoshitaka Aoki, Toyoki Kunitake, Shigenori Fujikawa

  LANGMUIR 24 8 4205 - 4208 2008年04月 [査読有り][通常論文]
   

  The fabrication of metallic nanostructures is one of the main issues in nanotechnology. This article describes the fabrication of a silver nanofin array by combining microlithography, electroless plating, and an etching technique. Fabricated Ag nanofins have a high aspect ratio (height/width = 10, width = 60 nm, height = 600 nm), and their widths and heights can be controlled by the period of electroless plating and the height of the original line pattern. An isolated Ag nanofin was proven to show metallic electrical conductivity. The current process provides a rapid and shape-designable fabrication method of metallic nanostructures.
• Enhanced proton conductivity of amorphous silicate nanofilms

  Y. Aoki, H. Habazakia, T. Kunitake

  ECS Transactions 16 51 407 - 412 2008年 [査読有り][通常論文]
   

  AlxSi1-xOn, films exhibit a drastic change of proton conductivity across the film by reducing its thickness to less than 100 nm. The temperature- and humidity-dependence of conductivity of the sub-100 nm films is quite different from those of the thicker films. Furthermore, in the former thickness range, the value of conductivity markedly increases with reducing the film thickness, and its thickness dependence follows a power law with a fixed index of -2.1. This size-scaling effect can be explained by the percolation conductivity model that the probability for percolating of the conductive moiety in AlxSi1-xOn, films increases with decreasing the thickness. ©The Electrochemical Society.
• Growth of porous anodic films on niobium in hot phosphate-glycerol electrolyte

  Y. Oikawa, K. Fushimi, Y. Aoki, H. Habazaki

  ECS Transactions 16 3 345 - 351 2008年 [査読有り][通常論文]
   

  Porous anodic films have been developed on niobium at constant formation voltages between 5 and 50 V in glycerol electrolyte containing 0.8 mol dm -3 dibasic potassium phosphate at 433 K. Except at the formation voltage of 5 V, at which the current density is approximately constant during anodizing, the current shows the minimum and then maximum. After the current maximum, the current density decreases gradually, which follows the Cottrell equation. Thus, diffusion of some species in the pores should control the growth rate of the anodic films. The porous films developed are practically Nb 2O5 with a small amount of carbon contamination. Incorporation of phosphorus species, which often occurs in aqueous electrolytes, is negligible at all the formation voltages in the present electrolyte. Based on the results obtained, the growth process of the porous anodic films on niobium in this hot organic electrolyte is discussed. © The Electrochemical Society.
• Thickness dependence of proton conductivity of amorphous aluminosilicate nanofilm

  Yoshitaka Aoki, H. Habazaki, Toyoki Kunitake

  ELECTROCHEMICAL AND SOLID STATE LETTERS 11 11 P13 - P16 2008年 [査読有り][通常論文]
   

  AlxSi1-xOn films exhibit a drastic change of proton conductivity across the film by reducing their thickness to less than 100 nm. The temperature and humidity dependence of conductivity of the sub-100 nm films is quite different from those of the thicker films. Furthermore, in the former thickness range, the value of conductivity markedly increases with reducing the film thickness, and its thickness dependence follows a power law with a fixed index of -2.1. This size-scaling effect can be explained by the percolation conductivity model that the probability for percolating of the conductive moiety in AlxSi1-xOn films increases with decreasing the thickness.
• Effects of antimuscarinics on voiding function after cerebral infarction in a rat model of overactive bladder

  Anwar Yusup, Hironobu Akino, Yoshiji Miwa, Nobuyuki Oyama, Yoshitaka Aoki, Hideaki Ito, Kazuya Tanase, Yosuke Matsuta, Masaharu Nakai, Osamu Yokoyama

  EUROPEAN JOURNAL OF PHARMACOLOGY 577 1-3 143 - 149 2007年12月 

  Muscarinic receptor antagonists are used clinically for their therapeutic peripheral effects on bladder function. However, these agents may also act on central muscarinic receptors, especially in individuals with compromised blood-brain barrier function. We compared the effects of atropine and tolterodine, agents that do and do not readily cross the blood-brain barrier, respectively, administered peripherally (intravenous [i.v.]) and centrally (intracerebroventricular [i.c.v.]) on cystometrography in conscious rats after cerebral infarction induced by middle cerebral artery occlusion or sham surgery. We hypothesized that tolterodine would produce greater improvement in bladder capacity and less impairment in bladder contractility and that the effects of both agents would be greater in rats with cerebral infarction and sham-operated rats after peripheral administration, but that tolterodine and atropine would exert similar effects after central administration. Bladder capacity was markedly reduced following cerebral infarction. Low-dose i.v. tolterodine (<= 20 nmol/kg) significantly reversed this effect without altering residual volume or bladder contraction pressure. Low-dose i.v. atropine (2 nmol/kg) had no effect on bladder capacity but significantly decreased bladder contraction pressure. Higher doses of i.v. atropine (>= 20 nmol/kg) significantly increased bladder capacity but also significantly increased residual volume and decreased bladder contraction pressure. Tolterodine was significantly more efficacious than atropine in increasing bladder capacity, whereas atropine produced significantly greater increases in residual volume and reductions in bladder contraction pressure; these treatment group differences were also observed in sham-operated animals. Tolterodine and atropine administered i.c.v. significantly increased bladder capacity following cerebral infarction or sham surgery; however, this was accompanied by significantly increased residual volume and decreased bladder contraction time. The decrease in bladder contraction time was significantly smaller after tolterodine vs atropine. Peripherally acting muscarinic receptor antagonists may be preferable to centrally acting agents for minimizing adverse events, such as incomplete bladder emptying, even in individuals with compromised blood-brain barrier function. (c) 2007 Elsevier B.V. All rights reserved.
• Antimuscarinic drug inhibits detrusor overactivity induced by topical application of prostaglandin E-2 to urethra with decrease in urethral pressure

  Osamu Yokoyama, Yoshiji Miwa, Nobuyuki Oyama, Yoshitaka Aoki, Hideaki Ito, Hironobu Akino

  JOURNAL OF UROLOGY 178 5 2208 - 2212 2007年11月 

  Purpose: Antimuscarinic drugs increase bladder capacity without prominent side effects such as urinary retention even when administered to patients with mild to moderate bladder outlet obstruction. Some mechanisms might exist in the urethra to compensate for the emptying function of the detrusor after the administration of antimuscarinic drugs. We investigated the influence of the antimuscarinic drug propiverine (Taiho Pharmaceutical, Tokyo, Japan) on urethral function.Materials and Methods: Urethral pressure and rhythmic bladder pressure were simultaneously monitored in urethane anesthetized female Sprague-Dawley rats. Prostaglandin E-2 was continuously administered intravesically or intraurethrally to induce detrusor overactivity. To eliminate the influence of bladder activity and monitor urethral baseline pressure isovolumetric pressure of the urethra was then recorded after cystectomy and ligation of the external urethral meatus. Furthermore, in vitro contractile responses of the urethral circular smooth muscle to field stimulation were examined in the presence of propiverine, tamsulosin (Taiho Pharmaceutical), verapamil, omega-conotoxin and atropine (Sigma(R)).Results: Intravesical or intraurethral administration of prostaglandin E-2 significantly decreased the bladder contraction interval by 10.7% and 36.0%, respectively. Intra-arterial administration of 2 x 10(2) nM/kg propiverine significantly increased the bladder contraction interval in rats receiving intraurethral prostaglandin E-2 by 81.8% but it had no marked effect on rats receiving intravesical prostaglandin E-2. Significant decreases in urethral baseline pressure were found after propiverine administration. Field stimulation induced contraction was inhibited by propiverine and verapamil but not by tamsulosin, omega-conotoxin or atropine. Conclusions: These results suggest that the inhibitory effects of propiverine are more prominent in rats with detrusor overactivity induced by intraurethral prostaglandin E-2 than by intravesical prostaglandin E-2. Propiverine may compensate for detrusor function by decreasing urethral resistance in the voiding phase.
• Response of La0.8Sr0.2CoO3  to perturbations on the CoO3 sublattice

  Z. Németh, Z. Homonnay, F. Árva, Z. Klencsár, E. Kuzmann, A. Vértes, J. Hakl, S. Mészáros, K. Vad, P. F. de Châtel, G. Gritzner, Y. Aoki, H. Konno, J. M. Greneche

  The European Physical Journal B 57 3 257 - 263 2007年06月 [査読有り][通常論文]
   

  Emission and transmission Mossbauer studies of La0.8Sr0.2CoO3-delta perovskites doped with similar to 0.02 stoichiometric units of oxygen vacancy or 2.5% iron corroborate the occurrence of electronic phase separation in these systems. The effect of the small perturbation of the CoO3 sublattice with either iron ions or oxygen vacancies on the bulk magnetization as well as on the Mossbauer spectra is in good agreement with the double exchange based cluster model. The magnetoresistance does not show any peak near the Curie temperature, but reaches -84% in a field of 7.5 T at T = 8 K. Below T-C approximate to 180 K the Mossbauer spectra distinctly include the contribution from paramagnetic and ferromagnetic regions, providing direct evidence for phase separation. No contribution to the spectra from Fe4+ ions can be observed, which is an unambiguous evidence that at low concentration iron (either directly doped or formed from Co-57 by nuclear decay) is accommodated in the cobaltate lattice as Fe3+ ion.
• Improvement in bladder storage function by tamsulosin depends on suppression of C-fiber urethral afferent activity in rats

  Osamu Yokoyama, Anwar Yusup, Nobuyuki Oyama, Yoshitaka Aoki, Yoshiji Miwa, Hironobu Akino

  JOURNAL OF UROLOGY 177 2 771 - 775 2007年02月 

  Purpose: alpha(1)-Blockers improve voiding symptoms by decreasing prostatic and urethral smooth muscle tone. However, to our knowledge the mechanism underlying improvements in storage symptoms is not known. Topical application of prostaglandin E, to the rat lower urinary tract stimulates the micturition reflex. Using an animal model we investigated whether the alpha(1)-blocker tamsulosin (Astellas Pharma, Tokyo, Japan) acts on C-fiber afferent activity and, if so, the location of this effect.Materials and Methods: To induce desensitization of C-fiber afferent activity resiniferatoxin (0.3 mg/kg) was subcutaneously injected in female Sprague-Dawley rats 2 days before experiments. Simultaneous recordings of urethral pressure and rhythmic bladder pressure were made with the rats under urethane anesthesia. Prostaglandin E-2 (0.4 mg/ml) was continuously administered intravesically or intraurethrally to rats pretreated with resiniferatoxin (resiniferatoxin rats) or rats without pretreatment (nonresiniferatoxin rats). We investigated the effects on the micturition reflex of intravenous (2.2 x 10(-1) to 2.2 x 10(3) nM/kg) or intrathecal (0.001 to 0.1 nmol) administration of tamsulosin.Results: The bladder contraction interval was markedly decreased after intravesical or intraurethral administration of prostaglandin E-2 in nonresiniferatoxin rats but it was unchanged in resiniferatoxin rats. This effect was antagonized by the EP1 receptor antagonist ONO-8711 (6-[(2S,3S)-3-(4-chloro-2-methylphenylsulfonylaminomethyl)-bicyclo[2.2.2]octan-2-yl]5Z-hexenoic acid). Intravenous administration of tamsulosin significantly increased the bladder contraction interval in nonresiniferatoxin rats receiving intraurethral prostaglandin E2 but it had no effect on nonresiniferatoxin rats receiving intravesical prostaglandin E,. Intrathecal administration of tamsulosin produced a slight and insignificant increase in the bladder contraction interval in nonresiniferatoxin rats receiving intraurethral prostaglandin E-2.Conclusions: These results suggest that prostaglandin E-2 enhances the micturition reflex through C-fiber afferents and tamsulosin had an inhibitory effect on the C-fiber urethral afferent nerves, thereby improving bladder storage function.
• Synthesis and Li+ intercalation/extraction in ultrathin V2O5 layer and freestanding V2O5/Pt/PVA multilayer films

  Yuanzhi Li, Toyoki Kunitake, Yoshitaka Aoki

  CHEMISTRY OF MATERIALS 19 3 575 - 580 2007年02月 [査読有り][通常論文]
   

  A uniform V2O5 nanostructured ultrathin film has been prepared by spin-coating followed by heat treatment. This V2O5 nanostructured ultrathin film is composed of 4 nm closely connected V2O5 domains and has lamellar structure. Compared with a thicker V2O5 film (78 nm), the 17 nm V2O5 film showed a very good electrochemical performance of fast charge/discharge and excellent electrochemical stability. The excellent electrochemical performance of the V2O5 nanostructured ultrathin film is attributed to its nanostructure, which results in short Li+ diffusion distance and free Li+ accessibility to intercalation active sites. A facile approach to preparing a freestanding V2O5/Pt/PVA multilayer film on a large scale was developed. The thicknesses of the V2O5, Pt, and PVA are 22, 57, and 704 nm, respectively. The freestanding multilayer is stable in air, flexible, and robust and exhibits excellent electrochemical performance.
• Efficient proton conduction in dry nanofilms of amorphous aluminosilicate

  Yoshitaka Aoki, Emi Muto, Shinya Onoue, Nakao Aiko, Toyoki Kunitake

  CHEMICAL COMMUNICATIONS 23 2396 - 2398 2007年 [査読有り][通常論文]
   

  Amorphous aluminosilicate nanofilms as prepared by a sol-gel process and post-annealing exhibit proton conduction at a wide temperature range in dry air with a lowest area specific resistance of 0.24 Omega cm(2) at 400 degrees C.
• Improvement of bladder storage function by alpha 1-blocker depends on the suppression of C-fiber afferent activity in rats

  Osamu Yokoyama, Anwar Yusup, Nobuyuki Oyama, Yoshitaka Aoki, Kazuya Tanase, Yosuke Matsuta, Yoshiji Miwa, Hironobu Akino

  NEUROUROLOGY AND URODYNAMICS 25 5 461 - 467 2006年 

  Aims: alpha 1-blockers improve voiding symptoms through the reduction of prostatic and urethral smooth muscle tone; however, the underlying mechanism of improvement of storage symptoms is not known. Using a rat model of detrusor overactivity caused by cerebral infarction (CI), we undertook the present study to determine whether the effect of an alpha 1-blocker, naftopidil, is dependent on the suppression of C-fiber afferents. Methods: To induce desensitization of C-fiber bladder afferents, we injected resiniferatoxin (0.3 mg/kg, RTX) sub-cutaneously to female Sprague-Dawley rats 2 days prior to left middle cerebral artery occlusion (MCAO) (RTX-CI rats). As controls we used rats without RTX treatment (CI rats). MCAO and insertion of a polyethylene catheter through the bladder dome were performed under halothane anesthesia. We investigated the effects on cystometrography (CMG) of intravenous (i.v.), intracerebroventricular (i.c.v.), or intrathecal (i.t.) administration of naftopidil in conscious Cl rats. Results: Bladder capacity (BC) was markedly reduced after MCAO in both RTX-CI and CI rats. I.v. administration of naftopidil significantly increased BC in Cl rats without an increase in residual volume, but it had no effects on BC in RTX-Cl rats. I.t. administration of naftopidil significantly increased BC in Cl but not in RTX-Cl rats. Conclusions: These results suggest that naftopidil has an inhibitory effect on C-fiber afferents in the lumbosacral spinal cord, improving BC during the storage phase.
• Electro-conductive nanotubular sheet of indium tin oxide as fabricated from the cellulose template

  Y Aoki, JG Huang, T Kunitake

  JOURNAL OF MATERIALS CHEMISTRY 16 3 292 - 297 2006年01月 [査読有り][通常論文]
   

  Free-standing, nanotubular ITO sheet with different In/Sn ratios was fabricated by the surface sol-gel process using cellulose filter paper as template. The resulting materials have a hierarchical structure originating from the morphology of cellulosic paper, and the ITO nanotubes are composed of interconnected layers of ITO nanocrystals of a few nanometres. Semiconducting behavior was observed at temperatures above room temperature, probably because electronic migration is strongly affected by the scattering at the boundary between nanocrystals. The ITO sheet with In/Sn ratio of 93.5/6.5 showed an intrinsic electronic conductivity (0.53 S cm(-1)) that is higher than those of other nanostructured ITO, and a very low apparent density (3.3% of neat ITO). These features indicate that the nanotubular ITO sheet has a potential use for chemical sensors and other devices.
• ポリマー混合溶液を用いた金属酸化物エピタキシャル薄膜の形成 : ポリマーアシスト析出法

  青木 芳尚

  化学と工業 = Chemistry and chemical industry 58 12 1458 - 1458 2005年12月01日 [査読無し][通常論文]
  
• Sol-gel fabrication of dielectric HfO2 nano-films; Formation of uniform, void-free layers and their superior electrical properties

  Y Aoki, T Kunitake, A Nakao

  CHEMISTRY OF MATERIALS 17 2 450 - 458 2005年01月 [査読有り][通常論文]
   

  Solution-based fabrication of a high-quality metal oxide nano-film (similar to10-nm thickness) by the surface sol-gel process and postannealing is reported. Hafnium(IV) n-butoxide in toluene-ethanol was chemisorbed onto hydroxylated Si wafer to give a uniform gel layer, of which alkoxide group was then hydrolyzed and subjected to a second cycle of chemisorption/hydrolysis. Annealing of a 10-cycle film at 500 degreesC produced uniform, void-free HfO2 layer of 5.7-nm thickness. Its electrical properties, dielectric constant, leakage current, and dielectric breakdown were comparable to the HfO2 film as prepared by the conventional vapor deposition method. On the other hand, a similar HfO2 nano-film prepared by spin-coating provided a less homogeneous layer in a high-resolution TEM image. The electrical properties of the latter film were much inferior to those of the surface sol-gel film. We concluded that the solution-based method is suitable for fabrication of dielectric nanofilms of metal oxide.
• Reducing gas sensing based on the redox interconversion of neodymium(III) chromate(V)

  Y Aoki, H Habazaki, H Konno

  CHEMISTRY LETTERS 33 8 992 - 993 2004年08月 [査読有り][通常論文]
   

  The novel sensing property of neodymium (III) chromate(V), NdCrO4, to methanol has been demonstrated. The electrical response of this compound did not rely on the surface potential change by the interaction with methanol gas, but was instead due to the redox interconversion of zircon-type (NdCrO4)-O-V to KDP-type (NdH2CrO4)-O-III. The NdCrO4 film prepared on alumina substrates with 2.5-mum thickness could respond to methanol of ppm order concentration with an apparent increase in electrical resistance.
• Solution-based fabrication of high- gate dielectrics for next-generation metal-oxide semiconductor transistors

  Y. Aoki, T. Kunitake

  Advanced Materials 16 2 118 - + 2004年01月 [査読有り][通常論文]
   

  The layer-by-layer adsorption of precursor metal alkoxides in solution and post-annealing at 400degreesC affords an alternate technique to the atomic layer chemical vapour deposition method for fabrication of next-generation high-kappa gate dielectrics. A void-free TiO(2)-La(2)O(3) composite film (see Figure) with 18 nm thickness is readily fabricated, and shows a dielectric constant higher than 30.
• Interconversion between rare-earth metal(III) chromates(V) and low-crystalline phases by reduction with methanol and oxidation in air

  Y Aoki, H Habazaki, H Konno

  CHEMISTRY OF MATERIALS 15 12 2419 - 2428 2003年06月 [査読有り][通常論文]
   

  Rare-earth metal(III) chromates(V), LaCrO(4), NdCrO(4), and Y(0.9)CrO(3.85), were found to show reversible structural changes by reduction with methanol and oxidation in air. This anomalous behavior was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, in situ Raman spectroscopy, and other methods. After less than 30 min of reduction at 543 K, zircon-type NdCrO(4) in the bulk scale changed to the low-crystalline II-KDP-type phase, which has the same arrangement of metal atoms as zircon. The reduced phase was quickly reverted to the zircon-type phase by air oxidation at 543 K for a few minutes. NdCrO(4) was reduced by hydrogen from methanol by forming hydrogen bonds between CrO(4) units, which caused the oxygen displacement and the formation of pseudo-octahedral CrO(6-m)(OH)(m) units, leading to the distorted II-YDP-type structure. Defect zircon-type Y(0.9)CrO(3.85) changed more quickly to the low-crystalline II-KDP-type phase than NdCrO(4), and the structure was not completely restored by the oxidation at 543 K for 1 h, because of the formation of small amounts of YCrO(3) and Cr(2)O(3). Monazite-type LaCrO(4) changed to an amorphous phase with the formation of the Schottky defects of oxide ions because of the structural differences between the monazite-type and II-KDP-type phases and was restored by air oxidation at 723 K.
• Solution-based fabrication of high-k gate dielectrics

  Y. Aoki, T. Kunitake

  Extended Abstracts of International Workshop on Gate Insulator, IWGI 2003 40 - 41 2003年 [査読有り][通常論文]
   

  In this paper, we conducted fabrication of ultrathin films from conventional dielectric materials MOx (M=Ti, Zr) as well as from binary oxide composites MOx-MOy (M=Ta, La).
• Synthesis of C/B4C composites from sugar-boric acid mixed solutions

  H Konno, A Sudoh, Y Aoki, H Habazaki

  MOLECULAR CRYSTALS AND LIQUID CRYSTALS 386 15 - 20 2002年 [査読有り][通常論文]
   

  B/C composites containing crystalline B4C particles were synthesized at 1400degreesC from the precursor composed of sugar-borate complexes. The precursors prepared from aqueous solutions of glucose and boric acid were found to be advantageous to the formation of B4C at low temperatures.
• Structure of EuCrO4 and its electronic and magnetic properties

  H Konno, Y Aoki, Z Klencsar, A Vertes, M Wakeshima, K Tezuka, Y Hinatsu

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 74 12 2335 - 2341 2001年12月 [査読有り][通常論文]
   

  Single phase zircon type EuCrO4 (S.G. I4(1)/amd) was synthesized and the structure including atomic positions was precisely determined by X-ray Rietveld refinement. The electronic and magnetic properties of the compound were studied based on the electric conductivity, Seebeck coefficient, Raman spectroscopy, Mossbauer spectroscopy, magnetic susceptibility, and specific heat. The CrO43- tetrahedra in EuCrO4 were slightly elongated compared with that in NdCrO4, which caused splitting of the degenerated vibration modes of CrO43-, nu(2) and nu(3), in the Raman spectra. The Eu-151 Mossbauer spectra showed not a trace of the Eu(II) species in the compounds measured in the present work. The Debye temperature, Theta(D), estimated from Mossbauer spectra suggested that the vibrational state of Eu(III) in EuCrO4 was similar to that in the perovskite-type EuCrO3. However, the isomer shift of Mossbauer spectra revealed that the electron density of the 6s orbital of Eu(III) in EuCrO4 was very low and almost the same as that in the zircon type EuVO4, that is, Eu(III) in these compounds has highly ionic character, whereas the electron density of the 6s orbital of Eu(III) in EuCrO3 was higher and nearly the same as that in Eu2O3. EuCrO4 was found to be an n-type semiconductor similar to NdCrO4, while zircon type REMO4 (RE: rare earth metal(III); M: V, P, As, etc.) are insulators. Magnetic susceptibility and specific heat measurements showed that antiferromagnetic transitions took place at around 15 K and was solely due to Cr(V) from the magnetic entropy value of 5.54 J mol(-1) K-1.
• Synthesis and structure of novel Cr-V-Cr-VI mixed valence compounds, Nd1-xCaxCrO4 (x=0.02-0.20)

  Y Aoki, H Konno

  JOURNAL OF SOLID STATE CHEMISTRY 156 2 370 - 378 2001年02月 [査読有り][通常論文]
   

  Single phase Nd1-xCaxCrO4 (x = 0-0.20) oxides were synthesized by the pyrolysis of precursors prepared from Nd-III-Ca-II-Cr-VI mixed solutions. Nd1-xCaxCrO4 having x greater than or equal to 0.25 was not obtained as a single phase. All Nd1-xCaxCrO4 were zircon type (tetragonal, I4(1)/amd), and the composition was almost stoichiometric without any essential defects, which was determined by chemical analyses. The lattice constants and atomic positions was refined by the X-ray Rietveld method. The calculated densities of Nd1-xCaxCrO4 (x = 0-0.20) were in good agreement with the ones measured by the picnometry. XPS and Raman spectra indicated that Nd1-xCaxCrO4 (x = 0.02-0.20) are mixed valence oxides containing two types of tetrahedra, (CrO43-)-O-V and (CrO42-)-O-VI) having D-2d symmetry in the structure, and this compensates the decrease of positive charges introduced by Ca-II ions. Though two types of tetrahedra were not distinguishable by XRD, lattice constants a and c decreased almost linearly with x. The values for x = 0.02-0.20, however, were not on the line expected by Vegard's law between NdCrO4 and CaCrO4 but larger. The calculated O-Cr-O bond angles, however, did not change monotonously as lattice constants and other crystallographic parameters such as Cr-O bond length did, indicating that CrO4 tetrahedra in Nd1-xCaxCrO4 (x = 0.02-0.20) are more elongated than in NdCrO4 and CaCrO4. It was deduced that the limit of x (about 0.25) may be determined by the difference in geometry between (CrO42-)-O-IV and (CrO43-)-O-V tetrahedra, (C) 2001 Academic Press.
• The electronic and magnetic properties of LaCrO4 and Nd1-xCaxCrO4 (x=0-0.2) and the conduction mechanism

  Y Aoki, H Konno, H Tachikawa

  JOURNAL OF MATERIALS CHEMISTRY 11 4 1214 - 1221 2001年 [査読有り][通常論文]
   

  The electric conductivity of monazite-type LaCrO4 and zircon-type Nd1-xCaxCrO4 (x = 0-0.2) were characterized by measurements of dc electric conductivity and the Seebeck coefficient in the 300-600 K range. The LaCrO4 and NdCrO4 were found to be n-type semiconductors, while commonly known monazite- or zircon-type oxides are insulators. In mixed valence compounds of Cr-V and Cr-VI, Nd1-xCaxCrO4 (x = 0.1, 0.2), hole hopping conduction arising from the mixed valency was also observed. The Nd1-xCaxCrO4 (x = 0.1, 0.2) compounds obeyed Curie-Weiss behavior above the Neel temperature, and the observed magnetic moments for the Cr-V ions were in good agreement with the theoretical values. Experimental results and the calculated spin densities by the UHF method indicated that most of the unpaired electrons from Cr-V were localized on Cr atoms. The ab initio MO calculations for CrO43- clusters in NdCrO4 revealed that the SOMO is the degenerate d pi* state and that the LUMO is the p sigma* state (O 2p origin): the SOMO forms the degenerate states at the top of the valence band and the LUMO forms a wide conduction band. For NdCrO4 and LaCrO4 the electronic conduction mechanism as semiconductors was explained by the band model. For Nd1-xCaxCrO4 (x = 0.1, 0.2) electronic conduction was described by the band model combined with hopping conduction of holes in degenerate d pi* states. It is concluded that the electronic conductivity of these compounds is caused by an intermixing of the ligand-to-metal charge-transfer (LMCT) state into the ionic configuration.
• Synthesis, structure and defects of rare earth chromates(V), RE0.9CrO3.85 (RE = Gd, Yb and Y)

  Y Aoki, H Konno

  JOURNAL OF MATERIALS CHEMISTRY 11 5 1458 - 1464 2001年 [査読有り][通常論文]
   

  Single phase zircon type rare earth (REIII) chromates(v), containing Gd-III, Yb-III and Y-III ions, were synthesized by pyrolysis of the precursors prepared from the mixed solutions of REIII and Cr-VI in the ratio of RE/Cr = 0.90/1.00. With other RE/Cr ratios, RE/Cr greater than or equal to 0.95 or RE/Cr less than or equal to 0.85, the pyrolysis products contained a secondary phase of RE2O3 or Cr2O3. The composition of the compounds was determined to be RE0.9CrO3.85 by chemical analyses, with small standard deviations. The ESR spectrum of Y0.9CrO3.85 was typical of Cr-V ions in solids with g = 1.968 and DeltaH = 140 mT, and did not show the signals of Cr-II or Cr-III. These compounds have a defect structure which differs from other zircon type compounds containing REIII of larger ionic radius than Gd-III. The detailed structure was determined by the powder X-ray Rietveld method. The measured densities suggested that the defect structure is RE0.9(CrO4)(0.85)(CrO3)(0.15) (RE = Gd, Yb and Y). Apparently this structure contains CrO3. with a dangling bond. Based on the structural analyses and ab initio MO calculations, these species might be stabilized by forming Cr2O7 (CrO3-O-CrO3) units in RE0.9CrO3.85 due to the oxygen sharing between CrO3. and the neighboring CrO4 tetrahedron. The present results conclude that the phase diagram of rare earth chromate(v) series reported so far should be corrected so that the compounds containing Gd-III and smaller ions have the defect zircon type structure.
• Formation of B/C composites containing B4C from sugar-organoborane complexes

  H Konno, T Erata, K Fujita, Y Aoki, K Shiba, N Inoue

  CARBON 39 5 779 - 782 2001年 [査読有り][通常論文]
  
• Characterization of LaCrO4 and NdCrO4 by XRD, Raman spectroscopy, and ab initio molecular orbital calculations

  Y Aoki, H Konno, H Tachikawa, M Inagaki

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 73 5 1197 - 1203 2000年05月 [査読有り][通常論文]
   

  Single phase LnCrO(4) (Ln = La-Nd) compounds were attempted to synthesize by the pyrolysis of precursors prepared from Ln(III)-Cr-VI mixed solutions. Only LaCrO4 and NdCrO4 were obtained as a single phase. LaCrO4 was monazite type (monoclinic, P2(1)/n), as reported, and the cell parameters were refined to be a = 0.70369, b = 0.72348, c = 0.66918 nm and beta = 104.950 degrees by an X-ray Rietveld method. NdCrO4 was zircon type (tetragonal, I4(1)/amd) and the eel parameters were a = 0.73107 and c = 0.66999 nm. It was found that CrO43- tetrahedra in LaCrO4 have C-1 symmetry and the four Cr-O bond lengths are different, whereas those in NdCrO4 have D-2d symmetry and all Cr-O bond lengths are 0.1702 nm. Detailed Raman spectra of LaCrO4 and NdCrO4 were measured and assigned to the vibrational modes of the CrO(4)(3-)tetrahedra. Molecular orbital calculations indicated that the charge density on the chromium ions in the tetrahedra is much less than the nominal 5+ due to the migratory electrons from oxygen atoms, and nearly the same irrespective of the symmetry of tetrahedron, suggesting that the Cr-O bonds are strongly covalent in nature.

MISC

• Corrosion Division Executive committee

  Laras Fadillah, Damian Kowlaski, Chunyu Zhu, Yoshitaka Aoki, Hiroki Habazaki Denki Kagaku 89 (1) 71 -72 2021年
• 酸素発生反応における高活性ブラウンミラーライト型Ca₂FeCoO₅触媒の開発

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• ブラウンミラーライト型Ca₂Fe_2-xCo^xO₅の酸素発生電極触媒活性

  野田裕之, 辻悦司, 辻悦司, 本橋輝樹, 青木芳尚, 小山幸典, 森正弘, 谷田肇, 内本喜晴, 荒井創, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2016 2016年
• Aサイトの一部を部分置換したLa-Mn-Ni系ペロブスカイト型酸化物の酸素還元・酸素発生電極触媒活性

  井上佳士, 辻悦司, 辻悦司, 本橋輝樹, 青木芳尚, 谷田肇, 内本喜晴, 荒井創, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2016 2016年
• 亜鉛‐空気二次電池の実用化に向けた酸素発生電極用高活性コバルト酸化物触媒の探索

  野田裕之, 辻悦司, 本橋輝樹, 青木芳尚, 小山幸典, 森正弘, 内本喜晴, 荒井創, 幅崎浩樹 電池討論会講演要旨集 56th 472 2015年11月10日 [査読無し][通常論文]
  
• コバルト系酸化物の遷移金属部分置換による構造変化と酸素発生触媒活性

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• RFスパッタ法によるBaCe_0.8Y_0.2O_3-δ電解質薄膜の作製とそれを用いた水素膜燃料電池の評価

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• マグネシウムアノード酸化皮膜の生成挙動

  片岡文崇, 辻悦司, 青木芳尚, 幅崎浩樹, 永田晋二 東北大学金属材料研究所新素材共同研究開発センター共同利用研究報告書 2014 72 -73 2015年06月 [査読無し][通常論文]
  
• RFスパッタ法によるBaCe_0.8Y_0.2O_3-δ電解質薄膜の作製と,それを用いた水素膜燃料電池の評価

  小林昌平, 青木芳尚, 辻悦司, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.1C24 2015年03月09日 [査読無し][通常論文]
  
• 異なる希土類元素を有するダブルペロブスカイト型Mn酸化物の酸素還元触媒活性

  野田裕之, 辻悦司, 本橋輝樹, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.3K20 2015年03月09日 [査読無し][通常論文]
  
• RFスパッタ法により作製したTiN_x薄膜の水素透過性

  倉千晴, 青木芳尚, 辻悦司, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.3H28 2015年03月09日 [査読無し][通常論文]
  
• 高温塩基性有機電解液中でのチタンのアノード酸化に与える無機塩添加の影響

  岡崎有杜, 辻悦司, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.PS84 2015年03月09日 [査読無し][通常論文]
  
• 高原子価Mn^V酸化物Ba₃(Mn_1-xV_xO₄)₂の中性水溶液中における電気化学的挙動

  小林泰星, 青木芳尚, 國貞雄治, 辻悦司, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.PS73 2015年03月09日 [査読無し][通常論文]
  
• Y(CrO₄)_1-x(PO₄)_xにおけるプロトン挿入脱離反応とそのPCFCカソードへの応用

  黒田孝亮, 青木芳尚, 辻悦司, 幅崎浩樹 電気化学会大会講演要旨集(CD-ROM) 82nd ROMBUNNO.PFC22 2015年03月09日 [査読無し][通常論文]
  
• アルミニウムメッシュの超撥水・超撥油化とその応用

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 131st 267 2015年02月20日 [査読無し][通常論文]
  
• フッ化物系マグネシウムアノード酸化皮膜生成のトレーサー研究

  片岡文崇, SHAHZAD Khurram, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹 表面技術協会講演大会講演要旨集 131st 265 2015年02月20日 [査読無し][通常論文]
  
• ステンレス鋼のフッ化物含有有機電解液中におけるアノード酸化挙動

  平賀拓也, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 131st 51 2015年02月20日 [査読無し][通常論文]
  
• LaCaMnNi系ペロブスカイト型酸化物の酸素還元・酸素発生電極触媒活性

  井上佳士, 辻悦司, 本橋輝樹, 青木芳尚, 谷田肇, 内本喜晴, 荒井創, 幅崎浩樹 電気化学秋季大会講演要旨集(CD-ROM) 2015 2015年
• 酸素不定比性を有するコバルト酸化物の酸素還元/酸素発生触媒活性

  辻悦司, 野田裕之, 本橋輝樹, 青木芳尚, 幅崎浩樹 電池討論会講演要旨集 55th 466 2014年11月19日 [査読無し][通常論文]
  
• スパッタ法により作成したBaCe_0.8Y_0.2O₃/水素膜燃料電池の発電性能

  青木芳尚, 小林昌平, 辻悦司, 幅崎浩樹, 八代圭司, 川田達也 固体イオニクス討論会講演要旨集 40th 187 -188 2014年11月16日 [査読無し][通常論文]
  
• 化学エッチング/アノード酸化によるAlメッシュの超撥油化とその応用

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹 日本学術会議材料工学連合講演会講演論文集 58th 460 -461 2014年10月27日 [査読無し][通常論文]
  
• Ti‐Zr合金のアノード酸化皮膜の誘電的性質に及ぼす予備酸化・熱処理の影響

  小林康平, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹 電気化学秋季大会講演要旨集 2014 90 2014年09月27日 [査読無し][通常論文]
  
• サイクリックボルタンメトリーによる結晶性アノード酸化チタニア膜の生成挙動の解明

  松浦志紀, 辻悦司, 青木芳尚, 幅崎浩樹 電気化学秋季大会講演要旨集 2014 13 2014年09月27日 [査読無し][通常論文]
  
• 結晶性多孔質アノード酸化TiO₂薄膜におけるスパッタチタン薄膜構造の影響と色素増感太陽電池特性

  辻悦司, 衡田直人, 青木芳尚, 永田晋二, 幅崎浩樹 表面技術協会講演大会講演要旨集 130th 212 2014年09月10日 [査読無し][通常論文]
  
• Annealing-free Electrochemical Preparation of Mesoporous Anatase Films for Application to Dye-sensitized Solar Cells

  HABAZAKI Hiroki, TSUJI Etsushi, AOKI Yoshitaka 応用物理学会秋季学術講演会講演予稿集(CD-ROM) 75th ROMBUNNO.19A-A4-3 2014年09月01日 [査読無し][通常論文]
  
• アルマイト皮膜の機能化技術 陽極酸化を利用した金属表面の超撥水・超撥油化

  幅崎浩樹, 藤井隆志, 中山勝利, 辻悦司, 青木芳尚 表面技術 65 (9) 426 -431 2014年09月01日 [査読無し][通常論文]
  
• マグネシウムアノード酸化皮膜の生成挙動

  幅崎浩樹, 片岡文崇, 辻悦司, 青木芳尚, 永田晋二 東北大学金属材料研究所新素材共同研究開発センター共同利用研究報告書 2013 70 -71 2014年06月 [査読無し][通常論文]
  
• 鉄上への多孔質アノード酸化皮膜/ポリピロール複合膜の形成と耐食性

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• 酸素不定比性を有する遷移金属酸化物の高濃度アルカリ水溶液中での酸素還元・酸素発生触媒活性

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• Ti‐Zr合金のアノード酸化皮膜の構造に及ぼす予備真空熱処理の影響

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• プロトン伝導性アモルファスZrP_2.5Ox薄膜のアニーリングによる微細構造変化

  菊谷和正, 青木芳尚, 辻悦司, 幅崎浩樹 電気化学会大会講演要旨集 81st 43 2014年03月29日 [査読無し][通常論文]
  
• アモルファスZrP_2.5O_x薄膜からなる水素膜燃料電池のカソード材料最適化

  小林昌平, 青木芳尚, 辻悦司, 幅崎浩樹 日本化学会講演予稿集 94th (2) 636 2014年03月12日 [査読無し][通常論文]
  
• アモルファスTiO_x薄膜のメモリスタ特性における酸素不定比性の影響

  倉千晴, 青木芳尚, 辻悦司, 永田晋二, 幅崎浩樹 日本化学会講演予稿集 94th (3) 1000 2014年03月12日 [査読無し][通常論文]
  
• マイクロドロップレットセルを用いたステンレス鋼上への耐食ゾル‐ゲルコーティングの評価

  木村大樹, 辻悦司, 青木芳尚, 矢野孝宜, HASSEL A. W, 幅崎浩樹 表面技術協会講演大会講演要旨集 129th 145 2014年03月03日 [査読無し][通常論文]
  
• 動電位アノード酸化法によるシュウ酸溶液中でのポーラスアノード酸化アルミナ皮膜の生成挙動の研究

  中山雄貴, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 129th 236 2014年03月03日 [査読無し][通常論文]
  
• ウェットプロセスを用いたAlメッシュの超撥油化

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 129th 239 2014年03月03日 [査読無し][通常論文]
  
• 多孔質アノード酸化アルミナを鋳型として合成したプレートレット構造カーボンナノファイバーへの白金担持と酸素還元電極特性

  山崎壮矩, 辻悦司, 青木芳尚, PARK Soo‐Gil, 幅崎浩樹 表面技術協会講演大会講演要旨集 129th 211 2014年03月03日 [査読無し][通常論文]
  
• フッ化物含有エチレングリコール溶液中におけるバリヤー型マグネシウムアノード酸化皮膜の生成

  片岡文崇, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹 表面技術協会講演大会講演要旨集 129th 250 2014年03月03日 [査読無し][通常論文]
  
• Ti‐Zr合金上に生成するアノード酸化皮膜のキャラクタリゼーション

  小林康平, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.2C10 2014年01月28日 [査読無し][通常論文]
  
• リン酸塩含有高温有機電解液中でのTiアノード酸化における基板構造の影響

  衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.2C19 2014年01月28日 [査読無し][通常論文]
  
• Al表面に生成する自己組織化単分子膜の構造解析

  佐藤妃奈, 辻悦司, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.1C19 2014年01月28日 [査読無し][通常論文]
  
• 金属水酸化物カソードを用いた水素膜燃料電池の発電特性

  小林昌平, 青木芳尚, 辻悦司, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.P45 2014年01月28日 [査読無し][通常論文]
  
• 燃料電池用水素透過膜アノード/プロトン伝導性ZrO₂‐WO₃電解質膜接合体の作製

  大庭博司, 青木芳尚, 辻悦司, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.2C12 2014年01月28日 [査読無し][通常論文]
  
• 電気化学的手法によるステンレス鋼表面の階層構造化と撥水・撥油特性

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.2C11 2014年01月28日 [査読無し][通常論文]
  
• リン酸塩含有高温有機電解液中における結晶性アノード酸化チタニア膜の生成機構

  松浦志紀, 辻悦司, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.1C20 2014年01月28日 [査読無し][通常論文]
  
• 酸素不定比性を有する金属酸化物の酸素還元/酸素発生電極触媒活性

  野田裕之, 辻悦司, 本橋輝樹, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集(CD-ROM) 2014 ROMBUNNO.1C07 2014年01月28日 [査読無し][通常論文]
  
• ウェットプロセスを用いたマイクロ‐ナノ形態制御による超撥油表面の創製

  幅崎浩樹, 中山勝利, 辻悦司, 青木芳尚 日本学術会議材料工学連合講演会講演論文集 57th 215 2013年11月25日 [査読無し][通常論文]
  
• 電気化学的手法によるステンレス鋼表面の階層構造化

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹 電気化学秋季大会講演要旨集 2013 64 2013年09月27日 [査読無し][通常論文]
  
• 液相鋳型炭素化法により作製した窒素含有カーボンナノファイバーの焼成温度と酸素還元特性

  辻悦司, 掛田興, 桐生雅彦, 青木芳尚, 幅崎浩樹 電気化学秋季大会講演要旨集 2013 243 2013年09月27日 [査読無し][通常論文]
  
• 多層スピンキャスト法によるステンレス鋼上への耐食ゾル‐ゲルコーティング

  木村大樹, 辻悦司, 青木芳尚, 幅崎浩樹, 矢野孝宜 表面技術協会講演大会講演要旨集 128th 158 2013年09月10日 [査読無し][通常論文]
  
• 化学エッチング/アノード酸化によるアルミニウム表面の超撥水・超撥油化

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 128th 162 -163 2013年09月10日 [査読無し][通常論文]
  
• Proton conductivity of amorphous anodic ZrO2-WO3-SiO2 nanofilms

  YE Ke, AOKI Yoshitaka, NAGATA Shinji, HABAZAKI Hiroki 東北大学金属材料研究所金属ガラス総合研究センター共同利用研究報告書 2012 15 -16 2013年06月 [査読無し][通常論文]
  
• 炭素鋼上でのアノード酸化における炭素種の皮膜生成に及ぼす影響

  紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹 材料と環境講演集 2013 275 -276 2013年04月30日 [査読無し][通常論文]
  
• フッ化物フリー電解液中でのアノード酸化メソ多孔質TiO₂皮膜の構造制御と結晶化

  辻悦司, 田口宜瑛, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 80th 359 2013年03月29日 [査読無し][通常論文]
  
• ジルコニアナノ結晶分散アノード酸化皮膜の形成とその誘電的性質

  幅崎浩樹, 石塚雅敏, 辻悦司, 青木芳尚, 坂口紀史, 永田晋二 電気化学会大会講演要旨集 80th 147 2013年03月29日 [査読無し][通常論文]
  
• ステンレス鋼表面のアノード酸化による超撥水化・撥油化

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 127th 192 2013年03月06日 [査読無し][通常論文]
  
• 熱処理を必要としない結晶性アノード酸化TiO₂薄膜の透明導電性ガラス上への作製と色素増感太陽電池への応用

  衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 127th 200 -201 2013年03月06日 [査読無し][通常論文]
  
• アルミニウム表面への自己組織化単分子膜形成に及ぼす基板前処理の影響

  佐藤妃奈, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 127th 189 -190 2013年03月06日 [査読無し][通常論文]
  
• アモルファス電解質膜/水素透過合金接合からなる薄膜燃料電池の中温発電特性

  野中亮, 青木芳尚, 辻悦司, 幅崎浩樹 電池討論会講演要旨集 53rd 438 2012年11月13日 [査読無し][通常論文]
  
• アノード酸化によるメソポーラスチタニア膜の形成とその機能

  田口宜瑛, 衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹 日本学術会議材料工学連合講演会講演論文集 56th 369 2012年10月29日 [査読無し][通常論文]
  
• YとSiを同時添加したZrアノード酸化皮膜の生成挙動とその誘電的性質

  石塚雅敏, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 126th 69 2012年09月12日 [査読無し][通常論文]
  
• プロトン伝導性アモルファス酸化物薄膜のキャラクタリゼーション

  YE Ke, 青木芳尚, 幅崎浩樹, 永田晋二 東北大学金属材料研究所金属ガラス総合研究センター共同利用研究報告書 2011 12 -13 2012年06月 [査読無し][通常論文]
  
• アルミニウム金属上へのアノード酸化による超撥水・超撥油表面の作製

  藤井隆志, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 125th 188 2012年03月01日 [査読無し][通常論文]
  
• 有機電解液を用いた各種金属上への多孔質アノード酸化皮膜の形成

  田口宜瑛, YANG Shu, 紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹 材料と環境討論会講演集 58th 181 -182 2011年09月16日 [査読無し][通常論文]
  
• Study on the Role of Cathodic Breakdown in AC PEO of Al in Alkaline Silicate Electrolyte

  SAH Santosh Prasad, TSUJI Etsushi, AOKI Yoshitaka, HABAZAKI Hiroki 電気化学秋季大会講演要旨集 2011 230 2011年09月09日 [査読無し][通常論文]
  
• βチタン合金のプラズマ電解酸化中の発光解析

  恒川聡, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 124th 106 2011年09月09日 [査読無し][通常論文]
  
• メソポーラスアノード酸化TiO₂皮膜の作製とその光触媒活性

  田口宜瑛, 辻悦司, 青木芳尚, 川喜多仁, 幅崎浩樹 表面技術協会講演大会講演要旨集 124th 105 2011年09月09日 [査読無し][通常論文]
  
• 鉄上への多孔質アノード酸化皮膜の生成に及ぼすアノード酸化条件の影響

  紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹 電気化学秋季大会講演要旨集 2011 229 2011年09月09日 [査読無し][通常論文]
  
• 撥水・撥油性に及ぼすナノ/サブマイクロ階層構造の表面形態の影響

  藤井隆志, 辻悦司, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 124th 103 2011年09月09日 [査読無し][通常論文]
  
• 表面ゾル‐ゲル法によるAl基板上への誘電体TiO₂超薄膜の形成

  三澤貴浩, 幅崎浩樹, 青木芳尚, 辻悦司, 小野昭二 電気化学秋季大会講演要旨集 2011 197 2011年09月09日 [査読無し][通常論文]
  
• 高容量ジルコニア系ナノコンポジットアノード酸化皮膜の形成

  小山瞬, 青木芳尚, 永田晋二, 幅崎浩樹 電気化学秋季大会講演要旨集 2011 198 2011年09月09日 [査読無し][通常論文]
  
• Cathodic Breakdown of Anodized Al-a Fundamental Study for AC PEO

  SAH Santosh Prasad, TSUJI Etsushi, AOKI Yoshitaka, HABAZAKI Hiroki 日本化学会北海道支部夏季研究発表会講演要旨集 2011 104 2011年07月01日 [査読無し][通常論文]
  
• プロトン伝導性アモルファスリン酸スズ薄膜の作製

  野中亮, 青木芳尚, 辻悦司, 幅崎浩樹 日本化学会北海道支部夏季研究発表会講演要旨集 2011 86 2011年07月01日 [査読無し][通常論文]
  
• プロトン伝導性アモルファス酸化物薄膜のキャラクタリゼーション

  FAN Ye, YE Ke, 青木芳尚, 幅崎浩樹, 永田晋二 東北大学金属材料研究所金属ガラス総合研究センター共同利用研究報告書 2010 50 -51 2011年06月 [査読無し][通常論文]
  
• 吸着単分子層検出のためのin‐situ XAFSの改良とPb‐UPDへの適用

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 稲葉雅之, 横溝臣智, 早川敬済, 中山武典 材料と環境講演集 2011 185 -188 2011年05月20日 [査読無し][通常論文]
  
• メソポーラスアノード酸化TiO₂皮膜の結晶性制御

  田口宜瑛, 青木芳尚, 幅崎浩樹, 川喜多仁 電気化学会大会講演要旨集 78th(CD-ROM) ROMBUNNO.1H29 2011年03月29日 [査読無し][通常論文]
  
• 異種元素添加によるジルコニウムアノード酸化皮膜の誘電特性の改善

  小山瞬, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 123rd 125 -126 2011年03月07日 [査読無し][通常論文]
  
• チタンおよびチタン合金への火花放電アノード酸化皮膜の形成と応用

  幅崎浩樹, 恒川聡, 三浦吉幸, SAH S. P, 青木芳尚, 伏見公志 表面技術協会講演大会講演要旨集 123rd 330 -333 2011年03月07日 [査読無し][通常論文]
  
• チタン合金へのプラズマ電解酸化による耐摩耗性コーティングの形成に及ぼす電解液温度の影響

  恒川聡, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 123rd 95 2011年03月07日 [査読無し][通常論文]
  
• タンタルアノード酸化皮膜の電気的性質に及ぼすニオブおよびタングステン添加の影響

  小宮山正造, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2011 78 2011年02月01日 [査読無し][通常論文]
  
• メソポーラスアノード酸化TiO₂皮膜の結晶配向制御

  田口宜瑛, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2011 155 2011年02月01日 [査読無し][通常論文]
  
• Pdアノード/アモルファスリン酸ジルコニウム電解質‐ヘテロ接合からなる薄膜燃料電池の発電特性

  福永悠希, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2011 53 2011年02月01日 [査読無し][通常論文]
  
• アモルファスリン酸ジルコニウム電解質薄膜とPdアノードからなる薄膜燃料電池の発電特性

  福永悠希, 青木芳尚, 幅崎浩樹 電池討論会講演要旨集 51st 315 2010年11月08日 [査読無し][通常論文]
  
• 斜め蒸着/アノード酸化による超撥水・超癈油表面の形成

  藤井隆志, 青木芳尚, 幅崎浩樹 日本学術会議材料工学連合講演会講演論文集 54th 364 2010年10月25日 [査読無し][通常論文]
  
• 斜め蒸着法による電解キャパシタ用非平衡合金ナノピラー膜の作製

  幅崎浩樹, TANVIR M.T, 青木芳尚 日本学術会議材料工学連合講演会講演論文集 54th 363 2010年10月25日 [査読無し][通常論文]
  
• アモルファスアルミノシリケート薄膜のAl/Si組成比によるプロトン伝導率スケーリング変化

  青木芳尚, 原田明寿, 幅崎浩樹 電気化学秋季大会講演要旨集 2010 75 2010年09月02日 [査読無し][通常論文]
  
• 表面ゾル‐ゲル法によるAl基板上への金属酸化物誘電体超薄膜の形成

  青木芳尚, 三澤貴浩, 幅崎浩樹 電気化学秋季大会講演要旨集 2010 183 2010年09月02日 [査読無し][通常論文]
  
• チタン合金上に生成したプラズマ電解酸化皮膜の構造解析

  恒川聡, 青木芳尚, 幅崎浩樹 電気化学秋季大会講演要旨集 2010 67 2010年09月02日 [査読無し][通常論文]
  
• 多孔質アノード酸化チタニア皮膜からハイブリッドキャパシタ用チタン酸リチウム電極の作製

  寺岡匡伸, 青木芳尚, PARK Soo‐Gil, 幅崎浩樹 表面技術協会講演大会講演要旨集 122nd 110 -111 2010年08月20日 [査読無し][通常論文]
  
• 鉄上への多孔質アノード酸化皮膜の形成

  紺野祥岐, 青木芳尚, 永田晋二, 幅崎浩樹 表面技術協会講演大会講演要旨集 122nd 112 2010年08月20日 [査読無し][通常論文]
  
• ゾルーゲル法によるAl上への誘電体酸化膜の形成

  三澤貴浩, 青木芳尚, 幅崎浩樹 日本化学会北海道支部夏季研究発表会講演要旨集 2010 45 2010年06月25日 [査読無し][通常論文]
  
• シリコン添加ジルコニアアノード酸化皮膜の電気特性

  小山瞬, 青木芳尚, 幅崎浩樹, 永田晋二, 木村久道 東北大学金属材料研究所金属ガラス総合研究センター共同利用研究報告書 2009 13 -14 2010年06月 [査読無し][通常論文]
  
• 微量のPb²⁺を含む酢酸緩衝水溶液中におけるNiの分極挙動

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 中山武典 材料と環境講演集 2010 345 -346 2010年04月26日 [査読無し][通常論文]
  
• フッ化物含有エチレングリコール中における鉄の多孔質アノード酸化皮膜の生成挙動

  紺野祥岐, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹 材料と環境講演集 2010 357 -358 2010年04月26日 [査読無し][通常論文]
  
• アモルファスアルミノシリケート薄膜におけるプロトン伝導度の組成依存性

  原田明寿, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 77th 457 2010年03月26日 [査読無し][通常論文]
  
• アモルファスリン酸ジルコニウム薄膜のプロトン伝導性

  小川幸太, 青木芳尚, 幅崎浩樹, 山口周 電気化学会大会講演要旨集 77th 310 2010年03月26日 [査読無し][通常論文]
  
• アモルファスシリケート薄膜の伝導率スケーリング挙動

  青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 77th 311 2010年03月26日 [査読無し][通常論文]
  
• β‐Ti合金上に生成するPEOコーティングの耐摩耗性と密着性の改善

  恒川聡, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 77th 453 2010年03月26日 [査読無し][通常論文]
  
• ジルコニウム合金に生成するアノード酸化皮膜の構造と誘電的性質

  小山瞬, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹 電気化学会大会講演要旨集 77th 277 2010年03月26日 [査読無し][通常論文]
  
• Pd合金とアモルファス電解質薄膜のヘテロ接合からなる中温作動用薄膜燃料電池の作製

  福永悠希, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 77th 483 2010年03月26日 [査読無し][通常論文]
  
• Nb‐Ta合金に生成するアノード酸化皮膜の生成挙動と誘電的性質

  小宮山正造, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹 表面技術協会講演大会講演要旨集 121st 238 -239 2010年02月26日 [査読無し][通常論文]
  
• スパッタ法により作製したカラム状アルミニウム合金膜の表面濡れ性に及ぼす表面形態の影響

  藤井隆志, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 121st 236 -237 2010年02月26日 [査読無し][通常論文]
  
• アルミニウムにシングルパルス電圧を印加して生成する火花放電皮膜の解析

  立野靖博, SAH S. P, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 121st 252 2010年02月26日 [査読無し][通常論文]
  
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼすAl添加の影響

  小山瞬, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹 表面技術協会講演大会講演要旨集 121st 240 -241 2010年02月26日 [査読無し][通常論文]
  
• アモルファスリン酸鉄水素透過膜の作製

  堀口匠, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 37 2010年01月26日 [査読無し][通常論文]
  
• アモルファスアルミノシリケート薄膜のプロトン伝導挙動

  原田明寿, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 113 2010年01月26日 [査読無し][通常論文]
  
• アモルファスAl_nP_mO_x薄膜のイオン伝導性

  平田周平, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 112 2010年01月26日 [査読無し][通常論文]
  
• 水素透過合金/アモルファス電解質薄膜―ヘテロ接合に基づく中温作動燃料電池の作製

  福永悠希, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 36 2010年01月26日 [査読無し][通常論文]
  
• シングルパルスアノード酸化によるアルミニウムの火花放電皮膜の生成挙動の解析

  立野靖博, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 21 2010年01月26日 [査読無し][通常論文]
  
• フッ化物を含むエチレングリコール中における鉄の多孔質アノード酸化皮膜の生成挙動

  紺野祥岐, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2010 114 2010年01月26日 [査読無し][通常論文]
  
• アモルファスシリケートM_0.1Si_0.9O_x薄膜における伝導率サイズスケーリングの添加元素M依存性

  青木芳尚, 幅崎浩樹 固体イオニクス討論会講演要旨集 35th 168 -169 2009年12月07日 [査読無し][通常論文]
  
• pHの異なる水溶液中におけるPbのUPDとNiの分極特性

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 中山武典 材料と環境討論会講演集 56th 157 -158 2009年09月11日 [査読無し][通常論文]
  
• タンタルアノード酸化皮膜の低電圧化成時の結晶化

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹 電気化学秋季大会講演要旨集 2009 254 2009年09月10日 [査読無し][通常論文]
  
• 10nm以下のポアサイズを有する多孔質アノード酸化チタニア皮膜の形成

  寺岡匡伸, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 120th 60 2009年09月07日 [査読無し][通常論文]
  
• アモルファスアノード酸化ZrO₂‐WO₃皮膜のプロトン伝導挙動

  KOWALSKI Damian, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 120th 68 2009年09月07日 [査読無し][通常論文]
  
• Ni電極上にUPDしたPbのin‐situ XAFS解析

  瀬尾眞浩, 青木芳尚, 伏見公志, 幅崎浩樹, 稲葉雅之, 横溝臣智, 早川敬済, 中山武典 材料と環境講演集 2009 243 -244 2009年05月08日 [査読無し][通常論文]
  
• アモルファスZrP₃O_x薄膜におけるプロトン伝導率の膜厚依存性

  小川幸太, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 76th 298 2009年03月29日 [査読無し][通常論文]
  
• 高温グリセリン溶液を用いたチタン上への二層多孔質アノード酸化皮膜の形成

  寺岡匡伸, 青木芳尚, 幅崎浩樹 電気化学会大会講演要旨集 76th 461 2009年03月29日 [査読無し][通常論文]
  
• アモルファスHf_nSi_1-nO_x薄膜における伝導率スケーリング挙動

  青木芳尚, 幅崎浩樹, 国武豊喜 電気化学会大会講演要旨集 76th 298 2009年03月29日 [査読無し][通常論文]
  
• 低化成電圧におけるタンタルアノード酸化皮膜の誘電的性質

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹 表面技術協会講演大会講演要旨集 119th 40 -41 2009年03月02日 [査読無し][通常論文]
  
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼすSi添加量の影響

  小山瞬, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 119th 105 -106 2009年03月02日 [査読無し][通常論文]
  
• 酸化還元能と自己支持性を有する金属酸化物‐高分子コンポジットナノ膜の合成

  堀口匠, 青木芳尚, 伏見公志, 幅崎浩樹 表面技術協会講演大会講演要旨集 119th 299 -300 2009年03月02日 [査読無し][通常論文]
  
• スパッタ法による多孔質AlおよびAl‐Nb膜の作製

  藤井隆志, 青木芳尚, 牧野猛, 小野昭二, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 32 2009年01月26日 [査読無し][通常論文]
  
• アモルファスZr‐P‐O薄膜のドライプロトン伝導挙動

  小川幸太, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 166 2009年01月26日 [査読無し][通常論文]
  
• Zr‐Si合金に生成するアノード酸化皮膜の誘電的性質

  小山瞬, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 36 2009年01月26日 [査読無し][通常論文]
  
• リン酸塩を含むグリセリン溶液を用いた多孔質アノード酸化チタニア皮膜の形成

  寺岡匡伸, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 167 2009年01月26日 [査読無し][通常論文]
  
• チタン合金に生成する耐摩耗性火花放電アノード酸化皮膜の密着性改善の試み

  三浦吉幸, 青木芳尚, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 28 2009年01月26日 [査読無し][通常論文]
  
• 低化成電圧時のタンタルアノード酸化皮膜の誘電特性に及ぼす大気酸化皮膜の影響

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹 化学系学協会北海道支部冬季研究発表会講演要旨集 2009 165 2009年01月26日 [査読無し][通常論文]
  
• アモルファスAl_nSi_1-nO_x薄膜におけるプロトン伝導率の膜厚依存性

  青木芳尚, 幅崎浩樹, 国武豊喜 固体イオニクス討論会講演要旨集 34th 57 -58 2008年12月03日 [査読無し][通常論文]
  
• リン酸塩を含む高温グリセリン溶液中におけるニオブアノード酸化皮膜の生成挙動に及ぼす水分量の影響

  及川祐樹, 伏見公志, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 118th 214 2008年08月20日 [査読無し][通常論文]
  
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼす添加元素の影響

  小山瞬, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 118th 215 2008年08月20日 [査読無し][通常論文]
  
• 電圧パルスの印加によるアルミニウムアノード酸化皮膜の絶縁破壊挙動の解析

  立野靖博, 伏見公志, 青木芳尚, 幅崎浩樹 表面技術協会講演大会講演要旨集 118th 224 -225 2008年08月20日 [査読無し][通常論文]
  
• アルミニウム微小電極を用いた火花放電アノード酸化プロセスの解析

  立野靖博, 伏見公志, 青木芳尚, 幅崎浩樹 日本化学会北海道支部研究発表会講演要旨集 2008 131 2008年07月19日 [査読無し][通常論文]
  
• V₂O₂/polymer複合層からなる自己支持性ナノ膜の合成

  堀口匠, 青木芳尚, 伏見公志, 幅崎浩樹 日本化学会北海道支部研究発表会講演要旨集 2008 130 2008年07月19日 [査読無し][通常論文]
  
• アモルファスシリケートナノ薄膜におけるドライプロトン伝導

  青木芳尚, 幅崎浩樹, 国武豊喜 電気化学会大会講演要旨集 75th 235 2008年03月29日 [査読無し][通常論文]
  
• GDOESによる耐食合金に生成する不働態皮膜の解析

  植村元宣, 青木芳尚, 伏見公志, 幅崎浩樹 表面技術協会講演大会講演要旨集 117th 111 2008年02月29日 [査読無し][通常論文]
  
• マイクロコーン型多孔質ニオブアノード酸化皮膜の形成とその撥水・撥油特性

  及川祐樹, 南貴之, 眞山博幸, 辻井薫, 青木芳尚, 伏見公志, 幅崎浩樹 表面技術協会講演大会講演要旨集 117th 268 -269 2008年02月29日 [査読無し][通常論文]
  
• スパッタ法によって生成する多孔質アルミニウム膜の形態に及ぼす雰囲気ガスの影響

  藤井隆志, 青木芳尚, 伏見公志, 幅崎浩樹, 牧野猛, 小野昭二 表面技術協会講演大会講演要旨集 117th 270 2008年02月29日 [査読無し][通常論文]
  
• チタンおよびチタン合金に生成する火花放電アノード酸化膜の密着性

  三浦吉幸, 青木芳尚, 伏見公志, 幅崎浩樹, 高沢祐之 表面技術協会講演大会講演要旨集 117th 271 -272 2008年02月29日 [査読無し][通常論文]
  
• Platelet構造を持つカーボンナノファイバーおよびナノチューブの作製とその電気化学キャパシタ特性

  桐生雅彦, 青木芳尚, 伏見公志, 金野英隆, 幅崎浩樹 三学協会北海道支部研究発表会講演要旨集 2008 41 2008年01月21日 [査読無し][通常論文]
  
• GDOESによる耐食合金の表面分析の最適化

  植村元宣, 青木芳尚, 伏見公志, 幅崎浩樹 三学協会北海道支部研究発表会講演要旨集 2008 29 2008年01月21日 [査読無し][通常論文]
  
• リン酸塩を含む高温グリセリン溶液中における多孔質ニオブアノード酸化皮膜の生成挙動

  及川祐樹, 青木芳尚, 伏見公志, 幅崎浩樹 三学協会北海道支部研究発表会講演要旨集 2008 40 2008年01月21日 [査読無し][通常論文]
  
• Characterization of amorphous anodic Nb2O5 nanofilm for gas sensing

  Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki ECS Transactions 16 (48) 57 -65 2008年 [査読無し][通常論文]
   

  Amorphous Nb2O5 film of 167 nm thickness was fabricated by anodic oxidation of sputter deposited niobium and characterized by TEM, GD-OES and AFM. The electric properties of the anodic films with sputter-deposited circular gold electrodes were studied by AC impedance spectroscopy in ambient gas atmospheres of air, argon, oxygen or hydrogen in the temperature range of 25 - 200°C. The amorphous Nb2O5 showed the character of n-type semiconductor. The conductivity of the film, following the Arrhenius behaviour, was independent of the oxygen partial pressure, but was largely dependent on hydrogen partial pressure. The conductivity of the Nb2O5 film at room temperature in dry hydrogen was 2.2 orders of magnitude as high as that in air. The enhanced conductivity could be associated with partial reduction of Nb5+ in dry hydrogen atmosphere. The addition of water vapor to hydrogen atmosphere reduced conductivity probably due to suppressing the reduction of Nb 2O5. ©The Electrochemical Society.
• リン酸塩を含む高温グリセリン溶液中における多孔質ニオブアノード酸化皮膜の生成挙動

  及川祐樹, 青木芳尚, 伏見公志, 幅崎浩樹 アルミニウム研究会誌 (5) 92 2008年 [査読無し][通常論文]
  
• 液相炭素化法による配向および形態を制御したナノカーボンの作製

  桐生雅彦, 青木芳尚, 伏見公志, 金野英隆, 幅崎浩樹 炭素材料学会年会要旨集 34th 370 -371 2007年11月28日 [査読無し][通常論文]
  
• フォトニック結晶を利用した色素増感型太陽電池効率向上の試み

  松下祥子, 玉木浩一, 礒島隆史, 青木芳尚, 東山祐太, 藤原良, 下村政嗣 電気化学会大会講演要旨集 74th 22 2007年03月29日 [査読無し][通常論文]
  
• アモルファスシリケートナノ薄膜におけるプロトン伝導性

  青木芳尚, 国武豊喜 電気化学会大会講演要旨集 74th 499 2007年03月29日 [査読無し][通常論文]
  
• 複合金属酸化物薄膜のイオン伝導

  青木芳尚, 国武豊喜 電気化学会大会講演要旨集 73rd 363 2006年04月01日 [査読無し][通常論文]
  
• 酸化チタンフォトニック結晶電極の電気化学特性

  松下祥子, 青木芳尚, 礒島隆史, 玉木浩一, 原正彦, 国武豊喜, 下村政嗣 日本化学会講演予稿集 86th (1) 294 2006年03月13日 [査読無し][通常論文]
  
• 色素増感型フォトニック結晶電極の粒径依存性

  松下I祥子, いそ島隆史, 青木芳尚, 玉木浩一, 国武豊喜, 原正彦, 下村政嗣 高分子学会予稿集(CD-ROM) 54 (2 Disk1) 2O04 2005年09月05日 [査読無し][通常論文]
  
• ナノ薄膜のガス吸着法による構造解析

  青木芳尚, 橋爪峰雄, 尾上慎弥, 国武豊喜 日本化学会講演予稿集 85th (1) 217 2005年03月11日 [査読無し][通常論文]
  
• 酸化物ナノ薄膜のBET法による構造評価

  青木芳尚, 橋爪峰雄, 尾上慎弥, 国武豊喜 高分子学会予稿集(CD-ROM) 53 (1) IIIPC045 2004年05月10日 [査読無し][通常論文]
  
• 液相法によるHigh‐k HfO₂超薄膜の作成

  青木芳尚, 国武豊喜 応用物理学関係連合講演会講演予稿集 51st (2) 880 2004年03月28日 [査読無し][通常論文]
  
• 液相法による酸化物誘電体ナノ薄膜の作成

  青木芳尚, 国武豊喜 第2回ナノテクノロジー総合シンポジウム講演予稿集 文部科学省ナノテクノロジー総合支援プロジェクト 平成16年 230 -231 2004年 [査読無し][通常論文]
  
• 表面ゾル‐ゲル法による酸化物超薄膜の作成とその誘電特性

  青木芳尚, 国武豊喜 応用物理学関係連合講演会講演予稿集 50th (2) 898 2003年03月27日 [査読無し][通常論文]
  
• 酸化還元によるジルコン型Nd^IIICr^VO₄の可逆的構造変化とその機構

  金野英隆, 青木芳尚 電気化学会大会講演要旨集 69th 161 2002年03月25日 [査読無し][通常論文]
  
• 希土類クロメイト(V)の可逆的形態変化

  青木芳尚, 幅崎浩樹, 金野英隆 固体の反応性討論会講演予稿集 12th 37 -39 2001年11月13日 [査読無し][通常論文]
  
• n‐ブタン/空気混合ガスとの反応によるNdCrO₄の可逆的構造変化と電気特性

  青木芳尚, 金野英隆, 幅崎浩樹 電気化学会大会講演要旨集 68th 171 2001年03月25日 [査読無し][通常論文]
  
• 糖類‐オルガノボラン錯体の熱分解によるB/C系複合材料の合成

  井上奈緒美, 恵良田知樹, 青木芳尚, 金野英隆 日本化学会北海道支部研究発表会講演要旨集 2001 84 2001年01月19日 [査読無し][通常論文]
  
• zircon型Cr^V‐Cr^VI混合原子価化合物の電気伝導性

  青木芳尚, 金野英隆 日本セラミックス協会年会講演予稿集 2000 170 2000年03月21日 [査読無し][通常論文]
  
• Zircon型LnCrO₄の電気伝導性とそのメカニズム

  青木芳尚, 金野英隆 日本化学会北海道支部研究発表会講演要旨集 2000 80 2000年01月21日 [査読無し][通常論文]
  
• Cr^V‐Cr^VI混合原子価化合物の合成,構造および電気伝導性

  青木芳尚, 金野英隆, 稲垣道夫 固体の反応性討論会講演予稿集 10th 17 -20 1999年09月 [査読無し][通常論文]
  
• 異常原子価Cr^vを含む希土類クロマイトの合成と電気伝導性

  青木芳尚, 金野英隆, 稲垣道夫 電気化学会大会講演要旨集 66th 345 1999年03月24日 [査読無し][通常論文]
  
• 異常原子価状態化合物LnCrO₄(Ln=La‐Nd)の合成と構造

  青木芳尚, 金野英隆, 田地川浩人, 稲垣道夫 日本化学会北海道支部研究発表会講演要旨集 1999 12 1999年02月02日 [査読無し][通常論文]
  
• 異常原子価状態の化合物LnCrO₄(Ln=La,Nd)の合成と構造

  青木芳尚, 金野英隆, 稲垣道夫 電気化学会大会講演要旨集 65th 325 1998年03月 [査読無し][通常論文]
  
• 異常原子価状態Cr(V)を含む化合物の合成とラマンスペクトルによる識別

  青木芳尚, 金野英隆, 稲垣道夫 日本化学会北海道支部研究発表会講演要旨集 1997 88 1997年08月 [査読無し][通常論文]
  
• 異常原子価化物LaCrO₄およびその置換型化合物の合成

  金野英隆, 青木芳尚, 稲垣道夫 電気化学会大会講演要旨集 64th 167 1997年03月 [査読無し][通常論文]
  

講演・口頭発表等

• プロトニック固体酸化物薄膜セルの発電特性(学術賞受賞講演)  [招待講演]

  日本電気化学会第88回大会 2021年03月 口頭発表（招待・特別）
• Incorporation of Bulk Proton Carriers in Manganese Perovskites Triggered By Charge Disproportionation between Metal and Oxygen Atoms  [招待講演]

  PRiME2020 2020年10月 口頭発表（招待・特別）
• Enhanced grain boundary hydride ion conduction of nanocrystalline metal nitride membranes  [招待講演]

  Y. Aoki

  5th Japan-Korea Joint Symposium on Hydrogen in Materials 2019年11月 口頭発表（招待・特別）
• Proton pumping boosts power generation of hydrogen permeable metal support fuel cells  [招待講演]

  Y. Aoki

  DAICHI Workshop on Proton Ceramics Fuel Cells/Electrolysis Cells 2019年09月 シンポジウム・ワークショップパネル（指名）
• Proton Pumping Boosts Power Generation of Hydrogen Permeable Metal Support Fuel Cells  [招待講演]

  第7回東北イオニクス合同ゼミ合宿 2019年08月 口頭発表（招待・特別）
• Enhanced Grain Boundary Diffusion of Hydride Ion in Nanocrystalline Metal Nitride Membranes  [招待講演]

  Y. Aoki

  Forums of Diffusion in Solids and Liquids (DSL 2019) 2019年07月 口頭発表（招待・特別）
• Enhanced Hydride Ion Conduction in Nanocrystalline Metal Nitride Membranes  [招待講演]

  Y. Aoki

  The 22nd International Conferences on Solid State Ionics 2019年06月 口頭発表（招待・特別）
• Direct Ammonia Type Fuel Cells Based on a Heterojunctions of Proton Conducting Oxide Electrolytes and Hydrogen Permeable Metal Anode  [招待講演]

  Y. Aoki

  World Hydrogen Technology Conferences WHTC 2019 2019年06月
• Manganese oxide base electrocatalysts for proton-conducting ceramic cells  [招待講演]

  Y. Aoki

  Nonstoichiometric Compounds VII 2019年03月 口頭発表（招待・特別）
• 中温領域で作動する直接アンモニア形水素膜型燃料電池の創製  [招待講演]

  青木芳尚

  水素エネルギー協会（HESS）第158回定例研究会 2019年03月 口頭発表（招待・特別）
• Enhanced grain boundary diffusion of hydrogen defects in metal nitrides  [招待講演]

  青木芳尚

  MS&T-18 2018年10月 口頭発表（招待・特別）
• Demonstration of fast hydride ion transport in nanocrystalline TiNx  [招待講演]

  青木芳尚

  19th International Conferences of Solid State Proton Conductors (SSPC-19) 2018年09月 口頭発表（招待・特別）
• 金属窒化物による常温水素膜の開発  [招待講演]

  青木芳尚

  表面技術協会 第138回研究会 2018年09月 口頭発表（招待・特別）
• Intermediate temperature solid electrolysis cells with BaZr0.6Ce0.2Y0.2O3-d electrolytes  [招待講演]

  青木芳尚

  MCARE2018 2018年08月 口頭発表（招待・特別）
• 水素分離膜/プロトン伝導体接合からなる中温作動型燃料電池の開発  [招待講演]

  青木芳尚

  FCH部会第250回定例研究会 2018年03月 シンポジウム・ワークショップパネル（指名）
• 窒化チタン微結晶膜におけるヒドリドイオン伝導の発現とそれによる常温水素膜分離  [招待講演]

  青木芳尚

  真空技術協会プラズマプロセス部会 第32回研究会 2017年10月 シンポジウム・ワークショップパネル（指名）
• Resistive switching triggered by bulk ion conduction of amorphous gallium oxide thin films  [招待講演]

  青木芳尚

  21th International Conferences of Solid State Ionics, 2017年07月 口頭発表（招待・特別）
• Electrochemical devices based on mixed conducting BaCe1-xYxO3/Pd hetrojunctions  [招待講演]

  青木芳尚

  Int. Symp. Rare Earth 2016 2016年09月 口頭発表（招待・特別）
• Design of ionics devices based on ion-electron mixed conducting oxide/metal heterojunctions  [招待講演]

  青木芳尚

  4th Int. Symp. Frontier Chemical Research Center 2016年02月 シンポジウム・ワークショップパネル（指名）
• Hydrogen permeability in Group IV transition metal nitride  [招待講演]

  青木芳尚

  MS&T-15 2015年09月 口頭発表（招待・特別）
• Thermochemical and electrochemical redox behavior of high valence state metal oxides  [通常講演]

  青木芳尚

  Petite workshop 2015 2015年02月 シンポジウム・ワークショップパネル（指名）
• Reversible redox behavior of NdCrO4 by insertion/desertion of proton through gas-solid reaction  [招待講演]

  青木芳尚

  Solid State Proton Conductors-17 (SSPC-17) 2014年09月 口頭発表（招待・特別）
• Bulk Mixed Ion Electron Conduction in Amorphous Gallium Oxide Causes Memristive Behaviour  [招待講演]

  青木芳尚

  7th Nagoya Univ.-Tsinghua Univ.-Toyota Motor Corp.-Hokkaido Univ. Joint Symposium ― Materials Science and Nanotechnology for the 21st Century ― 2014年07月 シンポジウム・ワークショップパネル（指名）
• Joint Japan-German research using the ‘French element’ Gallium for next generation electronics  [招待講演]

  青木芳尚

  German JSPS Meeting in Chitose 2014年05月 シンポジウム・ワークショップパネル（指名）
• プロトン伝導性アモルファスZrP_2.5Ox薄膜のアニーリングによる微細構造変化  [通常講演]

  菊谷和正, 青木芳尚, 辻悦司, 幅崎浩樹

  電気化学会第81回大会 2014年03月 口頭発表（一般）
• アモルファスZrP_2.5O_x薄膜からなる水素膜燃料電池のカソード材料最適化  [通常講演]

  小林昌平, 青木芳尚, 辻悦司, 幅崎浩樹

  日本化学会第94春季年会 2014年03月 ポスター発表
• アモルファスTiO_x薄膜のメモリスタ特性における酸素不定比性の影響  [通常講演]

  倉千晴, 青木芳尚, 辻悦司, 永田晋二, 幅崎浩樹

  日本化学会第94春季年会 2014年03月 ポスター発表
• 鉄上への多孔質アノード酸化皮膜/ポリピロール複合膜の形成と耐食性  [通常講演]

  紺野祥岐, 辻悦司, 青木芳尚, 大塚俊明, 幅崎浩樹

  電気化学会第81回大会 2014年03月 口頭発表（一般）
• 酸素不定比性を有する遷移金属酸化物の高濃度アルカリ水溶液中での酸素還元・酸素発生触媒活性  [通常講演]

  野田裕之, 辻悦司, 本橋輝樹, 青木芳尚, 竹口竜弥, 幅崎浩樹

  電気化学会第81回大会 2014年03月 ポスター発表
• Ti‐Zr合金のアノード酸化皮膜の構造に及ぼす予備真空熱処理の影響  [通常講演]

  小林康平, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹

  電気化学会第81回大会 2014年03月 口頭発表（一般）
• マイクロドロップレットセルを用いたステンレス鋼上への耐食ゾル‐ゲルコーティングの評価  [通常講演]

  木村大樹, 辻悦司, 青木芳尚, 矢野孝宜, HASSEL A. W, 幅崎浩樹

  表面技術協会第129回講演大会 2014年03月 口頭発表（一般）
• 多孔質アノード酸化アルミナを鋳型として合成したプレートレット構造カーボンナノファイバーへの白金担持と酸素還元電極特性  [通常講演]

  山崎壮矩, 辻悦司, 青木芳尚, PARK Soo‐Gil, 幅崎浩樹

  表面技術協会第129回講演大会 2014年03月 口頭発表（一般）
• 動電位アノード酸化法によるシュウ酸溶液中でのポーラスアノード酸化アルミナ皮膜の生成挙動の研究  [通常講演]

  中山雄貴, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第129回講演大会 2014年03月 口頭発表（一般）
• フッ化物含有エチレングリコール溶液中におけるバリヤー型マグネシウムアノード酸化皮膜の生成  [通常講演]

  片岡文崇, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹

  表面技術協会第129回講演大会 2014年03月 口頭発表（一般）
• ウェットプロセスを用いたAlメッシュの超撥油化  [通常講演]

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2014年03月 口頭発表（一般）
• Ti‐Zr合金上に生成するアノード酸化皮膜のキャラクタリゼーション  [通常講演]

  小林康平, 辻悦司, 青木芳尚, 永田晋二, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 ポスター発表
• リン酸塩含有高温有機電解液中でのTiアノード酸化における基板構造の影響  [通常講演]

  衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• Al表面に生成する自己組織化単分子膜の構造解析  [通常講演]

  佐藤妃奈, 辻悦司, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• 金属水酸化物カソードを用いた水素膜燃料電池の発電特性  [通常講演]

  小林昌平, 青木芳尚, 辻悦司, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 ポスター発表
• 燃料電池用水素透過膜アノード/プロトン伝導性ZrO₂‐WO₃電解質膜接合体の作製  [通常講演]

  大庭博司, 青木芳尚, 辻悦司, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• 電気化学的手法によるステンレス鋼表面の階層構造化と撥水・撥油特性  [通常講演]

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• リン酸塩含有高温有機電解液中における結晶性アノード酸化チタニア膜の生成機構  [通常講演]

  松浦志紀, 辻悦司, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• 酸素不定比性を有する金属酸化物の酸素還元/酸素発生電極触媒活性  [通常講演]

  野田裕之, 辻悦司, 本橋輝樹, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2014年冬季研究発表会 2014年01月 口頭発表（一般）
• Size effect of proton conductivity in disordered thin films  [招待講演]

  青木芳尚

  DJMM Workshop 2013 2013年12月 シンポジウム・ワークショップパネル（指名）
• ウェットプロセスを用いたマイクロ‐ナノ形態制御による超撥油表面の創製  [通常講演]

  幅崎浩樹, 中山勝利, 辻悦司, 青木芳尚

  第57回日本学術会議材料工学連合講演会 2013年11月 口頭発表（招待・特別）
• 電気化学的手法によるステンレス鋼表面の階層構造化  [通常講演]

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹

  2013年電気化学秋季大会 2013年09月 口頭発表（一般）
• 液相鋳型炭素化法により作製した窒素含有カーボンナノファイバーの焼成温度と酸素還元特性  [通常講演]

  辻悦司, 掛田興, 桐生雅彦, 青木芳尚, 幅崎浩樹

  2013年電気化学秋季大会 2013年09月 口頭発表（一般）
• 多層スピンキャスト法によるステンレス鋼上への耐食ゾル‐ゲルコーティング  [通常講演]

  木村大樹, 辻悦司, 青木芳尚, 幅崎浩樹, 矢野孝宜

  表面技術協会第128回講演大会 2013年09月 口頭発表（一般）
• 化学エッチング/アノード酸化によるアルミニウム表面の超撥水・超撥油化  [通常講演]

  中山勝利, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第128回講演大会 2013年09月 口頭発表（一般）
• Finite size effect of proton conductivity of amorphous oxide thin film  [招待講演]

  青木芳尚

  2013 International Joint Symposium between HU & HEU 2013年09月 シンポジウム・ワークショップパネル（指名）
• Finite size effect of proton conductivity of amorphous oxide thin films  [招待講演]

  青木芳尚

  7th International Conference on Science and Technology of Advanced Ceramic 2013年06月 口頭発表（招待・特別）
• 炭素鋼上でのアノード酸化における炭素種の皮膜生成に及ぼす影響  [通常講演]

  紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹

  材料と環境2013 2013年05月 口頭発表（一般）
• フッ化物フリー電解液中でのアノード酸化メソ多孔質TiO₂皮膜の構造制御と結晶化  [通常講演]

  辻悦司, 田口宜瑛, 青木芳尚, 幅崎浩樹

  電気化学会第80大会 2013年03月 ポスター発表
• ジルコニアナノ結晶分散アノード酸化皮膜の形成とその誘電的性質  [通常講演]

  幅崎浩樹, 石塚雅敏, 辻悦司, 青木芳尚, 坂口紀史, 永田晋二

  電気化学会第80大会 2013年03月 口頭発表（一般）
• 熱処理を必要としない結晶性アノード酸化TiO₂薄膜の透明導電性ガラス上への作製と色素増感太陽電池への応用  [通常講演]

  衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第127回講演大会 2013年03月 口頭発表（一般）
• アルミニウム表面への自己組織化単分子膜形成に及ぼす基板前処理の影響  [通常講演]

  佐藤妃奈, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第127回講演大会 2013年03月 口頭発表（一般）
• ステンレス鋼表面のアノード酸化による超撥水化・撥油化  [通常講演]

  呉冠文, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第127回講演大会 2013年03月 ポスター発表
• Finite size effect of proton conductivity of amorphous oxide thin film  [招待講演]

  青木芳尚

  International Joint Symposium between HU & CNU on Advanced Material Science & Technology 2012年12月 シンポジウム・ワークショップパネル（指名）
• アモルファス電解質膜/水素透過合金接合からなる薄膜燃料電池の中温発電特性  [通常講演]

  野中亮, 青木芳尚, 辻悦司, 幅崎浩樹

  第53回電池討論会 2012年11月 口頭発表（一般）
• アノード酸化によるメソポーラスチタニア膜の形成とその機能  [通常講演]

  田口宜瑛, 衡田直人, 辻悦司, 青木芳尚, 幅崎浩樹

  第56回日本学術会議材料工学連合講演会 2012年10月 口頭発表（一般）
• YとSiを同時添加したZrアノード酸化皮膜の生成挙動とその誘電的性質  [通常講演]

  石塚雅敏, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第126回講演大会 2012年09月 口頭発表（一般）
• Finite size effect of proton conductivity of sol-gel derived amorphous aluminosilicate thin films  [招待講演]

  青木芳尚

  Solid State Proton Conductors-16 (SSPC-16) 2012年09月 口頭発表（招待・特別）
• Switching behavior of highly-nonstoichiometeric GaOx thin films  [招待講演]

  青木芳尚

  2nd All Hands Meeting of SFB-917 ’Nanoswitches’ 2012年09月 口頭発表（招待・特別）
• Finite size effect of proton conductivity of sol-gel derived amorphous thin films  [招待講演]

  青木芳尚

  13th Asian Conference on Solid State Ionics 2012年07月 口頭発表（招待・特別）
• アルミニウム金属上へのアノード酸化による超撥水・超撥油表面の作製  [通常講演]

  藤井隆志, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第125回講演大会 2012年03月 口頭発表（一般）
• 有機電解液を用いた各種金属上への多孔質アノード酸化皮膜の形成  [通常講演]

  田口宜瑛, YANG Shu, 紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹

  第58回材料と環境討論会 2011年09月 口頭発表（一般）
• βチタン合金のプラズマ電解酸化中の発光解析  [通常講演]

  恒川聡, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第124回講演大会 2011年09月
• メソポーラスアノード酸化TiO₂皮膜の作製とその光触媒活性  [通常講演]

  田口宜瑛, 辻悦司, 青木芳尚, 川喜多仁, 幅崎浩樹

  表面技術協会第124回講演大会 2011年09月 口頭発表（一般）
• 撥水・撥油性に及ぼすナノ/サブマイクロ階層構造の表面形態の影響  [通常講演]

  藤井隆志, 辻悦司, 青木芳尚, 幅崎浩樹

  表面技術協会第124回講演大会 2011年09月 口頭発表（一般）
• 鉄上への多孔質アノード酸化皮膜の生成に及ぼすアノード酸化条件の影響  [通常講演]

  紺野祥岐, 辻悦司, 青木芳尚, 幅崎浩樹

  2011年電気化学秋季大会 2011年09月 口頭発表（一般）
• 表面ゾル‐ゲル法によるAl基板上への誘電体TiO₂超薄膜の形成  [通常講演]

  三澤貴浩, 幅崎浩樹, 青木芳尚, 辻悦司, 小野昭二

  2011年電気化学秋季大会 2011年09月
• 高容量ジルコニア系ナノコンポジットアノード酸化皮膜の形成  [通常講演]

  小山瞬, 青木芳尚, 永田晋二, 幅崎浩樹

  2011年電気化学秋季大会 2011年09月
• プロトン伝導性アモルファスリン酸スズ薄膜の作製  [通常講演]

  野中亮, 青木芳尚, 辻悦司, 幅崎浩樹

  日本化学会北海道支部2011年夏季研究発表会 2011年07月 口頭発表（一般）
• 吸着単分子層検出のためのin‐situ XAFSの改良とPb‐UPDへの適用  [通常講演]

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 稲葉雅之, 横溝臣智, 早川敬済, 中山武典

  材料と環境2014 2011年05月 口頭発表（一般）
• メソポーラスアノード酸化TiO₂皮膜の結晶性制御  [通常講演]

  田口宜瑛, 青木芳尚, 幅崎浩樹, 川喜多仁

  電気化学会第79回大会 2011年03月 口頭発表（一般）
• 異種元素添加によるジルコニウムアノード酸化皮膜の誘電特性の改善  [通常講演]

  小山瞬, 青木芳尚, 幅崎浩樹

  表面技術協会第123回講演大会 2011年03月 口頭発表（一般）
• チタンおよびチタン合金への火花放電アノード酸化皮膜の形成と応用  [通常講演]

  幅崎浩樹, 恒川聡, 三浦吉幸, SAH S. P, 青木芳尚, 伏見公志

  表面技術協会第123回講演大会 2011年03月 口頭発表（一般）
• チタン合金へのプラズマ電解酸化による耐摩耗性コーティングの形成に及ぼす電解液温度の影響  [通常講演]

  恒川聡, 青木芳尚, 幅崎浩樹

  表面技術協会第123回講演大会 2011年03月 口頭発表（一般）
• タンタルアノード酸化皮膜の電気的性質に及ぼすニオブおよびタングステン添加の影響  [通常講演]

  小宮山正造, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2011年冬季研究発表会 2011年02月 口頭発表（一般）
• メソポーラスアノード酸化TiO₂皮膜の結晶配向制御  [通常講演]

  田口宜瑛, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2011年冬季研究発表会 2011年02月 口頭発表（一般）
• Pdアノード/アモルファスリン酸ジルコニウム電解質‐ヘテロ接合からなる薄膜燃料電池の発電特性  [通常講演]

  福永悠希, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部2011年冬季研究発表会 2011年02月 口頭発表（一般）
• アモルファスリン酸ジルコニウム電解質薄膜とPdアノードからなる薄膜燃料電池の発電特性  [通常講演]

  福永悠希, 青木芳尚, 幅崎浩樹

  電池討論会講演要旨集 2010年11月
• 斜め蒸着/アノード酸化による超撥水・超癈油表面の形成  [通常講演]

  藤井隆志, 青木芳尚, 幅崎浩樹

  日本学術会議材料工学連合講演会講演論文集 2010年10月
• 斜め蒸着法による電解キャパシタ用非平衡合金ナノピラー膜の作製  [通常講演]

  幅崎浩樹, TANVIR M.T, 青木芳尚

  日本学術会議材料工学連合講演会講演論文集 2010年10月
• アモルファスアルミノシリケート薄膜のAl/Si組成比によるプロトン伝導率スケーリング変化  [通常講演]

  青木芳尚, 原田明寿, 幅崎浩樹

  電気化学秋季大会講演要旨集 2010年09月
• 表面ゾル‐ゲル法によるAl基板上への金属酸化物誘電体超薄膜の形成  [通常講演]

  青木芳尚, 三澤貴浩, 幅崎浩樹

  電気化学秋季大会講演要旨集 2010年09月
• チタン合金上に生成したプラズマ電解酸化皮膜の構造解析  [通常講演]

  恒川聡, 青木芳尚, 幅崎浩樹

  電気化学秋季大会講演要旨集 2010年09月
• 多孔質アノード酸化チタニア皮膜からハイブリッドキャパシタ用チタン酸リチウム電極の作製  [通常講演]

  寺岡匡伸, 青木芳尚, PARK Soo‐Gil, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年08月
• 鉄上への多孔質アノード酸化皮膜の形成  [通常講演]

  紺野祥岐, 青木芳尚, 永田晋二, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年08月
• ゾルーゲル法によるAl上への誘電体酸化膜の形成  [通常講演]

  三澤貴浩, 青木芳尚, 幅崎浩樹

  日本化学会北海道支部夏季研究発表会講演要旨集 2010年06月
• シリコン添加ジルコニアアノード酸化皮膜の電気特性  [通常講演]

  小山瞬, 青木芳尚, 幅崎浩樹, 永田晋二, 木村久道

  東北大学金属材料研究所金属ガラス総合研究センター共同利用研究報告書 2010年06月
• 微量のPb²⁺を含む酢酸緩衝水溶液中におけるNiの分極挙動  [通常講演]

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 中山武典

  材料と環境講演集 2010年04月
• フッ化物含有エチレングリコール中における鉄の多孔質アノード酸化皮膜の生成挙動  [通常講演]

  紺野祥岐, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹

  材料と環境講演集 2010年04月
• アモルファスアルミノシリケート薄膜におけるプロトン伝導度の組成依存性  [通常講演]

  原田明寿, 青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2010年03月
• アモルファスリン酸ジルコニウム薄膜のプロトン伝導性  [通常講演]

  小川幸太, 青木芳尚, 幅崎浩樹, 山口周

  電気化学会大会講演要旨集 2010年03月
• アモルファスシリケート薄膜の伝導率スケーリング挙動  [通常講演]

  青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2010年03月
• β‐Ti合金上に生成するPEOコーティングの耐摩耗性と密着性の改善  [通常講演]

  恒川聡, 青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2010年03月
• ジルコニウム合金に生成するアノード酸化皮膜の構造と誘電的性質  [通常講演]

  小山瞬, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹

  電気化学会大会講演要旨集 2010年03月
• Pd合金とアモルファス電解質薄膜のヘテロ接合からなる中温作動用薄膜燃料電池の作製  [通常講演]

  福永悠希, 青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2010年03月
• Nb‐Ta合金に生成するアノード酸化皮膜の生成挙動と誘電的性質  [通常講演]

  小宮山正造, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年02月
• スパッタ法により作製したカラム状アルミニウム合金膜の表面濡れ性に及ぼす表面形態の影響  [通常講演]

  藤井隆志, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年02月
• アルミニウムにシングルパルス電圧を印加して生成する火花放電皮膜の解析  [通常講演]

  立野靖博, SAH S. P, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年02月
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼすAl添加の影響  [通常講演]

  小山瞬, 青木芳尚, 永田晋二, 木村久道, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2010年02月
• アモルファスリン酸鉄水素透過膜の作製  [通常講演]

  堀口匠, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• アモルファスアルミノシリケート薄膜のプロトン伝導挙動  [通常講演]

  原田明寿, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• アモルファスAl_nP_mO_x薄膜のイオン伝導性  [通常講演]

  平田周平, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• 水素透過合金/アモルファス電解質薄膜―ヘテロ接合に基づく中温作動燃料電池の作製  [通常講演]

  福永悠希, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• シングルパルスアノード酸化によるアルミニウムの火花放電皮膜の生成挙動の解析  [通常講演]

  立野靖博, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• フッ化物を含むエチレングリコール中における鉄の多孔質アノード酸化皮膜の生成挙動  [通常講演]

  紺野祥岐, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2010年01月
• アモルファス金属酸化物薄膜におけるプロトン伝導率スケーリング現象の発  [招待講演]

  青木芳尚

  平成21年度日本化学会北海道支部冬季研究発表会 2010年01月 口頭発表（招待・特別）
• アモルファスシリケートM_0.1Si_0.9O_x薄膜における伝導率サイズスケーリングの添加元素M依存性  [通常講演]

  青木芳尚, 幅崎浩樹

  固体イオニクス討論会講演要旨集 2009年12月
• pHの異なる水溶液中におけるPbのUPDとNiの分極特性  [通常講演]

  瀬尾眞浩, 伏見公志, 青木芳尚, 幅崎浩樹, 中山武典

  材料と環境討論会講演集 2009年09月
• タンタルアノード酸化皮膜の低電圧化成時の結晶化  [通常講演]

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹

  電気化学秋季大会講演要旨集 2009年09月
• 10nm以下のポアサイズを有する多孔質アノード酸化チタニア皮膜の形成  [通常講演]

  寺岡匡伸, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2009年09月
• アモルファスアノード酸化ZrO₂‐WO₃皮膜のプロトン伝導挙動  [通常講演]

  KOWALSKI Damian, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2009年09月
• Power-law scaling of proton conductivity of amorphous silicate thin films  [招待講演]

  青木芳尚

  17th International Symposium on Solid State Ionics 2009年07月 口頭発表（招待・特別）
• Ni電極上にUPDしたPbのin‐situ XAFS解析  [通常講演]

  瀬尾眞浩, 青木芳尚, 伏見公志, 幅崎浩樹, 稲葉雅之, 横溝臣智, 早川敬済, 中山武典

  材料と環境講演集 2009年05月
• アモルファスZrP₃O_x薄膜におけるプロトン伝導率の膜厚依存性  [通常講演]

  小川幸太, 青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2009年03月
• 高温グリセリン溶液を用いたチタン上への二層多孔質アノード酸化皮膜の形成  [通常講演]

  寺岡匡伸, 青木芳尚, 幅崎浩樹

  電気化学会大会講演要旨集 2009年03月
• アモルファスHf_nSi_1-nO_x薄膜における伝導率スケーリング挙動  [通常講演]

  青木芳尚, 幅崎浩樹, 国武豊喜

  電気化学会大会講演要旨集 2009年03月
• 低化成電圧におけるタンタルアノード酸化皮膜の誘電的性質  [通常講演]

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2009年03月
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼすSi添加量の影響  [通常講演]

  小山瞬, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2009年03月
• 酸化還元能と自己支持性を有する金属酸化物‐高分子コンポジットナノ膜の合成  [通常講演]

  堀口匠, 青木芳尚, 伏見公志, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2009年03月
• スパッタ法による多孔質AlおよびAl‐Nb膜の作製  [通常講演]

  藤井隆志, 青木芳尚, 牧野猛, 小野昭二, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• アモルファスZr‐P‐O薄膜のドライプロトン伝導挙動  [通常講演]

  小川幸太, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• Zr‐Si合金に生成するアノード酸化皮膜の誘電的性質  [通常講演]

  小山瞬, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• リン酸塩を含むグリセリン溶液を用いた多孔質アノード酸化チタニア皮膜の形成  [通常講演]

  寺岡匡伸, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• チタン合金に生成する耐摩耗性火花放電アノード酸化皮膜の密着性改善の試み  [通常講演]

  三浦吉幸, 青木芳尚, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• 低化成電圧時のタンタルアノード酸化皮膜の誘電特性に及ぼす大気酸化皮膜の影響  [通常講演]

  小宮山正造, 青木芳尚, 泉知夫, 幅崎浩樹

  化学系学協会北海道支部冬季研究発表会講演要旨集 2009年01月
• アモルファスAl_nSi_1-nO_x薄膜におけるプロトン伝導率の膜厚依存性  [通常講演]

  青木芳尚, 幅崎浩樹, 国武豊喜

  固体イオニクス討論会講演要旨集 2008年12月
• リン酸塩を含む高温グリセリン溶液中におけるニオブアノード酸化皮膜の生成挙動に及ぼす水分量の影響  [通常講演]

  及川祐樹, 伏見公志, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2008年08月
• ジルコニウムアノード酸化皮膜の誘電特性に及ぼす添加元素の影響  [通常講演]

  小山瞬, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2008年08月
• 電圧パルスの印加によるアルミニウムアノード酸化皮膜の絶縁破壊挙動の解析  [通常講演]

  立野靖博, 伏見公志, 青木芳尚, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2008年08月
• アルミニウム微小電極を用いた火花放電アノード酸化プロセスの解析  [通常講演]

  立野靖博, 伏見公志, 青木芳尚, 幅崎浩樹

  日本化学会北海道支部研究発表会講演要旨集 2008年07月
• V₂O₂/polymer複合層からなる自己支持性ナノ膜の合成  [通常講演]

  堀口匠, 青木芳尚, 伏見公志, 幅崎浩樹

  日本化学会北海道支部研究発表会講演要旨集 2008年07月
• アモルファスシリケートナノ薄膜におけるドライプロトン伝導  [通常講演]

  青木芳尚, 幅崎浩樹, 国武豊喜

  電気化学会大会講演要旨集 2008年03月
• GDOESによる耐食合金に生成する不働態皮膜の解析  [通常講演]

  植村元宣, 青木芳尚, 伏見公志, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2008年02月
• マイクロコーン型多孔質ニオブアノード酸化皮膜の形成とその撥水・撥油特性  [通常講演]

  及川祐樹, 南貴之, 眞山博幸, 辻井薫, 青木芳尚, 伏見公志, 幅崎浩樹

  表面技術協会講演大会講演要旨集 2008年02月
• スパッタ法によって生成する多孔質アルミニウム膜の形態に及ぼす雰囲気ガスの影響  [通常講演]

  藤井隆志, 青木芳尚, 伏見公志, 幅崎浩樹, 牧野猛, 小野昭二

  表面技術協会講演大会講演要旨集 2008年02月
• チタンおよびチタン合金に生成する火花放電アノード酸化膜の密着性  [通常講演]

  三浦吉幸, 青木芳尚, 伏見公志, 幅崎浩樹, 高沢祐之

  表面技術協会講演大会講演要旨集 2008年02月
• Platelet構造を持つカーボンナノファイバーおよびナノチューブの作製とその電気化学キャパシタ特性  [通常講演]

  桐生雅彦, 青木芳尚, 伏見公志, 金野英隆, 幅崎浩樹

  三学協会北海道支部研究発表会講演要旨集 2008年01月
• GDOESによる耐食合金の表面分析の最適化  [通常講演]

  植村元宣, 青木芳尚, 伏見公志, 幅崎浩樹

  三学協会北海道支部研究発表会講演要旨集 2008年01月
• リン酸塩を含む高温グリセリン溶液中における多孔質ニオブアノード酸化皮膜の生成挙動  [通常講演]

  及川祐樹, 青木芳尚, 伏見公志, 幅崎浩樹

  三学協会北海道支部研究発表会講演要旨集 2008年01月
• リン酸塩を含む高温グリセリン溶液中における多孔質ニオブアノード酸化皮膜の生成挙動  [通常講演]

  及川祐樹, 青木芳尚, 伏見公志, 幅崎浩樹

  アルミニウム研究会誌 2008年
• 液相炭素化法による配向および形態を制御したナノカーボンの作製  [通常講演]

  桐生雅彦, 青木芳尚, 伏見公志, 金野英隆, 幅崎浩樹

  炭素材料学会年会要旨集 2007年11月
• フォトニック結晶を利用した色素増感型太陽電池効率向上の試み  [通常講演]

  松下祥子, 玉木浩一, 礒島隆史, 青木芳尚, 東山祐太, 藤原良, 下村政嗣

  電気化学会大会講演要旨集 2007年03月
• アモルファスシリケートナノ薄膜におけるプロトン伝導性  [通常講演]

  青木芳尚, 国武豊喜

  電気化学会大会講演要旨集 2007年03月
• 複合金属酸化物薄膜のイオン伝導  [通常講演]

  青木芳尚, 国武豊喜

  電気化学会大会講演要旨集 2006年04月
• 酸化チタンフォトニック結晶電極の電気化学特性  [通常講演]

  松下祥子, 青木芳尚, 礒島隆史, 玉木浩一, 原正彦, 国武豊喜, 下村政嗣

  日本化学会講演予稿集 2006年03月
• 色素増感型フォトニック結晶電極の粒径依存性  [通常講演]

  松下I祥子, いそ島隆史, 青木芳尚, 玉木浩一, 国武豊喜, 原正彦, 下村政嗣

  高分子学会予稿集(CD-ROM) 2005年09月
• ナノ薄膜のガス吸着法による構造解析  [通常講演]

  青木芳尚, 橋爪峰雄, 尾上慎弥, 国武豊喜

  日本化学会講演予稿集 2005年03月
• Wet Fabrication of Metal Oxide Gate Insulator  [招待講演]

  青木芳尚

  5th Japan-France Workshop on Nanomaterials Research 2004年10月 口頭発表（招待・特別）
• Solution-based Fabrication of the Metal Oxide Nanofilm by Surface Sol-Gel Process.  [招待講演]

  青木芳尚

  ALD2004 2004年08月 シンポジウム・ワークショップパネル（指名）
• 酸化物ナノ薄膜のBET法による構造評価  [通常講演]

  青木芳尚, 橋爪峰雄, 尾上慎弥, 国武豊喜

  高分子学会予稿集(CD-ROM) 2004年05月
• 液相法によるHigh‐k HfO₂超薄膜の作成  [通常講演]

  青木芳尚, 国武豊喜

  応用物理学関係連合講演会講演予稿集 2004年03月
• 液相法による酸化物誘電体ナノ薄膜の作成  [通常講演]

  青木芳尚, 国武豊喜

  第2回ナノテクノロジー総合シンポジウム講演予稿集 文部科学省ナノテクノロジー総合支援プロジェクト 平成16年 2004年
• 表面ゾル‐ゲル法による酸化物超薄膜の作成とその誘電特性  [通常講演]

  青木芳尚, 国武豊喜

  応用物理学関係連合講演会講演予稿集 2003年03月
• 酸化還元によるジルコン型Nd^IIICr^VO₄の可逆的構造変化とその機構  [通常講演]

  金野英隆, 青木芳尚

  電気化学会大会講演要旨集 2002年03月
• 希土類クロメイト(V)の可逆的形態変化  [通常講演]

  青木芳尚, 幅崎浩樹, 金野英隆

  固体の反応性討論会講演予稿集 2001年11月
• n‐ブタン/空気混合ガスとの反応によるNdCrO₄の可逆的構造変化と電気特性  [通常講演]

  青木芳尚, 金野英隆, 幅崎浩樹

  電気化学会大会講演要旨集 2001年03月
• 糖類‐オルガノボラン錯体の熱分解によるB/C系複合材料の合成  [通常講演]

  井上奈緒美, 恵良田知樹, 青木芳尚, 金野英隆

  日本化学会北海道支部研究発表会講演要旨集 2001年01月
• zircon型Cr^V‐Cr^VI混合原子価化合物の電気伝導性  [通常講演]

  青木芳尚, 金野英隆

  日本セラミックス協会年会講演予稿集 2000年03月
• Zircon型LnCrO₄の電気伝導性とそのメカニズム  [通常講演]

  青木芳尚, 金野英隆

  日本化学会北海道支部研究発表会講演要旨集 2000年01月
• 異常原子価Cr^vを含む希土類クロマイトの合成と電気伝導性  [通常講演]

  青木芳尚, 金野英隆, 稲垣道夫

  電気化学会大会講演要旨集 1999年03月
• 異常原子価状態化合物LnCrO₄(Ln=La‐Nd)の合成と構造  [通常講演]

  青木芳尚, 金野英隆, 田地川浩人, 稲垣道夫

  日本化学会北海道支部研究発表会講演要旨集 1999年02月
• 異常原子価状態の化合物LnCrO₄(Ln=La,Nd)の合成と構造  [通常講演]

  青木芳尚, 金野英隆, 稲垣道夫

  電気化学会大会講演要旨集 1998年03月
• 異常原子価状態Cr(V)を含む化合物の合成とラマンスペクトルによる識別  [通常講演]

  青木芳尚, 金野英隆, 稲垣道夫

  日本化学会北海道支部研究発表会講演要旨集 1997年08月
• 異常原子価化物LaCrO₄およびその置換型化合物の合成  [通常講演]

  金野英隆, 青木芳尚, 稲垣道夫

  電気化学会大会講演要旨集 1997年03月

担当経験のある科目（授業）

化学英語北海道大学工学部応用化学
電子材料特論北海道大学大学院総合化学院
創造工学演習北海道大学総合理工
熱力学演習北海道大学工学部応用化学
物理化学I北海道大学工学部応用化学

所属学協会

• ヨーロッパ材料学会   アメリカ電気化学会   固体イオニクス学会   日本電気化学会   

共同研究・競争的資金等の研究課題

• バイポーラー固体電解セルの基盤技術創製

  日本学術振興会：科学研究費助成事業

  研究期間 : 2024年04月 -2027年03月 

  代表者 : 青木 芳尚
• 低温作動水素透過膜支持型燃料電池の研究開発

  NEDO：燃料電池等利用の飛躍的拡大に向けた共通課題解決型産学官連携研究開発事業／水素利用等高度化 先端技術開発

  研究期間 : 2021年11月 -2025年03月
• 表面水素工学の学理構築と活用に関する研究総括

  日本学術振興会：科学研究費助成事業

  研究期間 : 2021年08月 -2024年03月 

  代表者 : 森 浩亮, 青木 芳尚, 日沼 洋陽, 本倉 健, 三輪 寛子

   

  気相の水素分子が、酸化物表面上に吸着した金属を介して高活性な単原子として流れ出し、高速に拡散する『水素スピルオーバー』現象の原理原則は未だブラックボックスである。本領域では、スピルオーバーにより生成した活性水素種を使いこなすための制御因子を正しく理解し、またその画期的な活用法の提案に取り組んだ。 実験班の森(A01)、本倉(A02)、青木(A03)は、それぞれ革新材料合成、新触媒プロセス、電気化学セルの開発に取り組み、水素スピルーバーの新たな利用法を提案した。同じく実験班の三輪(A05)は、水素様素粒子であるミュオンをプローブにスピルオーバー水素の動的な挙動を直接観察するための予備的な基礎情報取得に努めた。理論計算班の日沼(A04)は、スピルオーバーメカニズムの理論的・系統的理解を独自に進め、さらに実験班に対し理論的裏付けの提供、あるいは理論的な提言を行った。また、総括班では、全体領域会議を3 回開催し、班員間の連携の場を提供した。また、班員の研究支援として、SPring-8、KEK-PF、大阪大学超高圧電子顕微鏡センターの共同利用機器を利用できるように便宜を図った。
• プロトンポンピング効果によるセラミックス燃料電池の作動温度低減

  日本学術振興会：科学研究費助成事業

  研究期間 : 2021年04月 -2024年03月 

  代表者 : 青木 芳尚

   

  水素透過膜支持型燃料電池(HMFC)は水透過合金/電解質膜－ヘテロ界面での酸化物イオンブロッキングにより発現するプロトンポンピング効果を発現し、高い出力を生むことが知られている。水素透過膜支持型燃料電池(HMFC)における、プロトンポンピング効果の最大化を目標に以下の検討を行った。第一に電解質酸化物の酸素欠損量がプロトンポンピングに及ぼす影響を実証するために，異なる酸素の非化学量論比をもつBaZr1－xScxO3－2/x (x = 0.2 and 0.5)を電解質としたHMFCについて実験とシミュレーションによる解析を行った。これらの解析によって，酸素欠損量の多いBaZr0.5Sc0.5O3－δではプロトンポンピング効果がより顕著に発現されるため，カソード近傍のプロトンの界面移動がより促進されることがわかった。さらに，プロトンポンピング効果によって促進されたプロトンの界面移動は，水の生成および脱離反応を促進することで三相界面における触媒活性サイトを速やかに再生させて酸素の表面交換反応を促進し，それによってカソード反応が吸着酸素種の拡散を伴わない経路を辿った結果，カソード分極抵抗が著しく小さくなることがわかった。従って，BaZr0.5Sc0.5O3－δからなるHMFCは，400 °Cの低い作動温度でも0.54 Ω cm2の小さな分極抵抗を実現し，0.4 W cm－2を超えるピーク出力を達成できた。この値は，従来のPCFCの性能を大きく上回るものである。これらの結果は，HMFCがカソード分極における過電圧をより効率的に活用できるシステムであることを示している。
• 表面水素工学：水素スピルオーバーに基づく新規イオニクスデバイスの開発

  日本学術振興会：科学研究費補助金 学術変革領域(B)

  研究期間 : 2021年10月 -2024年03月 

  代表者 : 青木 芳尚
• ヒドリド伝導性電極を使ったCO2還元再資源化反応の開拓

  日本学術振興会：科学研究費助成事業

  研究期間 : 2021年07月 -2023年03月 

  代表者 : 青木 芳尚

   

  金属酸水素化物は、水素化物（H-）イオンの導電率と酸化還元活性の相乗効果により、電気化学エネルギー材料および触媒的材料として注目されている。一方で、多くの酸水素化物は過酷な調製条件と高温熱分解性により、エネルギーデバイスなどへの応用が制限される。本研究では、高いH-イオン電子混合導電率と、高温耐久性の高いペロブスカイト酸水素化物BaZr0.5In（II）0.5O2.25H0.5を発見した。母相であるBaZr0.5In（III）0.5O2.75は、大気圧下H2中で800°Cでアニーリングすると、In原子が還元され、また2つのIn間架橋O原子(O-InIn)の欠損とH-イオンを挿入が起こり、トポタクティック水素化反応を生じることがわかった。水素化に伴う格子収縮は非常に小さく（-0.05%）従ってBaZr0.5In0焼結体を破壊することなくバルク水素化し、BaZr0.5In（II）0.5O2.25H0.5緻密焼結体を作製することができる。このようにして多孔質Niサーメット支持体上に高密度のBaZr0.5In0.5O2.25H0.5薄膜をもつ膜デバイスを、簡単な焼結プロセスによって作製することができた。また得られたデバイスは、500°Cで10-3 S cm-2相当のH-イオン伝導率により顕著な水素透過性を示した。本研究で得られた材料は、セラミック電気化学セルの混合導電性電極および水素透過膜支持体への応用することで、H2O-CO2共電解プロセス、およびCO2再資源化プロセスの効率を飛躍的に向上させると期待される。
• 実用的中温作動型水素膜燃料電池の開発

  科学技術振興事業団：未来社会創造事業 「地球規模での低炭素社会の実現」領域探索加速型

  研究期間 : 2017年11月 -2022年03月 

  代表者 : 青木芳尚
• ヒドリド伝導性水素膜とそれに基づくメンブレンリアクターの基盤技術創成

  日本学術振興会：科学研究費助成事業（基盤(B)）

  研究期間 : 2018年04月 -2021年03月 

  代表者 : 青木芳尚
• 亜鉛空気電池用実用的空気極触媒の開発

  新エネルギー・産業技術開発機構：革新型実用蓄電池基盤技術開発(RISING2)

  研究期間 : 2016年10月 -2021年03月 

  代表者 : 幅崎浩樹, 青木芳尚, 北野翔
• 高原子価Mn(V)酸化物による水の酸化反応の開拓

  日本学術振興会：科学研究費助成事業（萌芽研究）

  研究期間 : 2015年04月 -2017年03月 

  代表者 : 青木芳尚
• 中温領域で作動する直接アンモニア形水素膜燃料電池の創製

  JST：さきがけ再生可能エネルギーからのエネルギーキャリアの製造とその利用のための革新的基盤技術の創製」領域

  研究期間 : 2014年10月 -2017年03月 

  代表者 : 青木芳尚
• プロトン伝導性アノード酸化膜を新規電解質とする中温燃料電池の創製

  日本学術振興会：科学研究費助成事業(基盤(B))

  研究期間 : 2012年04月 -2015年03月 

  代表者 : 幅崎浩樹
• 水素透過膜燃料電池におけるアモルファス電解質膜/金属電極―ヘテロ界面の設計

  東京応化財団：研究助成

  研究期間 : 2013年04月 -2014年03月 

  代表者 : 青木芳尚
• 中温域新規プロトン伝導性酸化物ナノ薄膜の電気化学合成

  日本学術振興会：科学研究費助成事業（萌芽研究）

  研究期間 : 2011年04月 -2013年03月 

  代表者 : 幅崎浩樹
• Investigation of size-scaling behavior in insulator-metal transition of highly-nonstoichiometric, amorphous gallium oxide thin film

  Alexander von Humbold Fundation：AvH Fellowship

  研究期間 : 2011年02月 -2012年05月 

  代表者 : 青木芳尚
• 電子―プロトン混合パーコレーション伝導体の創製と電極触媒能

  日本学術振興会：科学研究費補助金（若手研究(A)）

  研究期間 : 2010年04月 -2012年03月 

  代表者 : 青木 芳尚

   

  Brφnsted酸性電子-プロトン混合伝導体(EPmix)薄膜を創出するのための検討課題は以下の2点である。第一に高い酸性度と混合伝導率をもつEPmix複合酸化物薄膜の合成方法を最適化すること。第二に高いシート伝導度と垂直水素透過速度を同時に満たす、混合パーコレーション伝導体の設計方法を確立することである。本研究ではNb-P-Co混合アルコキシド溶液を用いた多層スピンキャスト法により、400℃ドライ雰囲気下で高い垂直混合伝導率を示すNb_<1.2>Co_<1.4>P_2O_x-アモルファス複合酸化物薄膜を合成することに成功した。この薄膜(100nmd)は明らかな水素透過能を示し、水素輸送に関する活性化エネルギーは約0.4eVと比較的小さな値を示した。また400℃における水素透過率は約10^<-7>molm^<-2>Pa^<-0.5>オーダーであり、これは燃料電池において2.0Acm^2の電流密度を生成するのに十分な値である。水素透過Pd合金をアノード基板、アモルファスZrP_<2.6>O_x薄膜(130nmd)を電解質膜、およNb_<1.2>Co_<1.4>P_2O_x-EPmix薄膜(200nmd)をカソードに用いた薄膜燃料電池を作製し、出力特性を調べた。薄膜燃料電池は350℃において理論値に匹敵する開回路電圧1.05V、最高出力2mWcm^<-2>を示した。セル抵抗の主な原因はアノードにおける分極であることが分かった。来年以降は、電極界面における分極抵抗低減とセル発電効率のさらなる向上を目指し研究を進める予定である。
• 中温作動型薄膜燃料電池のための電解質薄膜/金属アノード接合技術の開発

  JST：シーズ発掘試験A（発掘型）

  研究期間 : 2009年06月 -2010年03月 

  代表者 : 青木芳尚
• アモルファス酸化物ナノ膜におけるパーコレーションイオン伝導のサイズ効果

  文部科学省：科学研究費補助金（若手研究(B)）

  研究期間 : 2008年04月 -2010年03月 

  代表者 : 青木 芳尚

   

  a-M_nSi_<1-n>O_x薄膜の膜厚が100nm以下に減少すると、プロトン伝導率がべき乗則で増加する、いわゆるサイズスケーリング現象が発見された。a-M_nSi<1-n>O_xは、低伝導マトリクスと高伝導パス(Bronsted 酸点:-O-Si^<4+>-O-M^-O-ヘテロ結合)からなる不均一構造を有している。この高伝導パスのつながり、いわゆる'クラスター'がプロトンチャンネルとして働く。膜厚dが最大クラスターのサイズζより大きい場合(バルク状態)、伝導パスのパーコレーションは起こらない。dがζにほぼ等しくなると(臨界点)、伝導パスのパーコレーションが起こり、σは増加する。更にdが減少すると、より小さなクラスターもパーコレーションするためその数N_p はd_<-μ>に従い増加し、こうしてσのスケーリングが起こる。本研究の結果は、アモルファスイオン伝導体にはバルク平均値より高いコンダクタンスの微細構造(伝導パス)が存在することを示唆しており、a-Al_<0.1>Si^<0.9>O_x薄膜の場合、伝導パスは平均長約20nmのアルミノシリカ鎖であることが示された。本研究の結果は、アモルファス酸化物の分子組成などを変えることにより、さらに新しい伝導率増強効果が発見される可能性が示唆された。
• 軽金属表面のプラズマ電気化学コーティングによる機能化とそのプロセスの解明

  日本学術振興会：科学研究費助成事業

  研究期間 : 2007年 -2010年 

  代表者 : 幅崎 浩樹, 伏見 公志, 青木 芳尚

   

  プラズマ電気化学プロセスは,高温プロセスが使えないアルミニウム,マグネシウムやチタンなどの軽金属の表面に,常温の水溶液中において10～100μm厚さのセラミックスコーティングを形成することが可能なプロセスである。本研究では,酸化膜にできた放電ポアの修復にケイ酸塩水溶液が優れていることを微小電気化学手法を用いて初めて明らかにした。また,高強度で冷間加工性に優れたチタン合金への耐摩耗性・高密着性セラミックスコーティングの形成法を確立した。
• フォトニック結晶による光エネルギー変換効率向上の取り組み

  日本学術振興会：科学研究費助成事業

  研究期間 : 2005年 -2006年 

  代表者 : 松下・I 祥子, 磯島 隆史, 玉木 浩一, 青木 芳尚

   

  本申請は、フォトニック結晶を利用して色素増感型太陽電池の効率向上を試みるものである。フォトニック結晶とは光波長程度の周期構造体で、規則構造表面の光近接場が共鳴することにより光を閉じ込めることができる光デバイスである。 色素増感型太陽電池では、まず色素の電子が入射光hν_1により励起される。励起された電子が酸化チタンに移ることにより電気が流れる。しかしこのとき、励起された電子のすべてが酸化チタンへ移るのではなく、何割かの電子は色素内の発光hν_2に使われる。申請者は、この色素の発光をフォトニック結晶で抑制することにより、一色素あたりの光電変換効率が向上するのではないかと考え、色素増感型フォトニック結晶電極の作製を行い光電変換効率を測定したところ、一色素あたりの光電変換効率が向上するという結果を得た。 フォトニック結晶としては、化学的修飾が容易な自己集積型フォトニック結晶を使用している。本年度は特に、光機能界面における近接場共鳴を見るため、表面凹凸が極端に少ない機能性フォトニック結晶の作製を行った(BCSJ, in press.)。特に、良い再現性を得るために自己集積化技術の向上を試み、依頼総説の執筆および4件の招待講演を行わせていただいた。また、本フォトニック結晶を利用して、化学吸着した色素のみを残して色素増感型太陽電池の効率、全散乱スペクトル、光音響スペクトルの測定、さらにフォトニックバンドダイアグラムの計算を行い、国内外発表7件、また下記業績以外に論文2報をsubmitした。
• 導電性アモルファス酸化物の超薄膜からなる規則多孔体の作成

  日本学術振興会：科学研究費補助金（若手研究(B)）

  研究期間 : 2003年04月 -2005年03月 

  代表者 : 青木 芳尚

   

  本研究は表面ゾル-ゲル法とテンプレート合成法を組み合わせることにより、導電性金属酸化物のナノ構造体により骨格形成された、規則多孔体を作成することを目的としている。前年度までの研究において、我々はセルロース繊維(ろ紙).をテンプレートに用いて表面ゾル-ゲル法をおこなうことにより、壁厚:10-20nm、直径:100-300nm、長さ:2-15μmのチューブ状インジウム-スズ複合酸化物(ITO)が3次元的に絡み合った多孔質構造体を生成することに成功した。これらのITO多孔質構造体は、高い気孔率(>80vol%)であるにもかかわらず室温において高い導電率を示し、中でもインジウムとスズの元素比(In/Sn)が9/1のものは最も高い導電率、0.53Scm^<-1>を示した。In/Sn=9/1の試料に対し、空間充填率を用いて理論密度100%のときの見かけの伝導率を計算したところ、20Scm^<-1>となり、これはスパッタリング法で作成した厚さ20nmの高品質ITO薄膜の導電率とほぼ等しいことがわかった。本研究で作成したITO多孔質材料では、セルロース繊維におけるマクロスケールのネットワーク構造がそのままITOネットワークとして転写されている。従って、そのITOネットワーク構造が電子のパーコレーション経路を形成し、高い気候率にもかかわらず良い導電性を生み出すものと考えられる。これらのITO多孔質構造体は、その構造的・電気的特徴から、センサー、光電変換システムなど、様々な次世代デバイスへの応用が期待される。

産業財産権

• 特願2021-039946:水素透過材料  2021年03月12日

  青木芳尚  北海道大学
• 特願PCT/JP2018/047935:水素分離用膜  2018年11月21日

  青木芳尚, 倉千晴, 幅崎浩樹  北海道大学
• 特願PCT/JP2018/ 41555:酸素発生電極触媒とその利用法  2018年11月08日

  幅崎浩樹, 青木芳尚, Damian Kowalski
• 特願2018-210890:酸素発生電極用ナノクラスター触媒  2018年11月08日

  幅崎浩樹, 青木芳尚, Damian Kowalski
• 特願PCT/JP2018/ 31116:酸素発生電極用導電助剤  2018年08月23日

  幅崎浩樹, 青木芳尚, Damian Kowalski
• 特願2018-032702:プロトンセラミックス燃料電池及びその製造方法  2018年02月17日

  青木芳尚, 山口智之, 幅崎浩樹
• 特願2017-353650:窒化チタンナノ結晶膜による水素分離膜  2017年11月22日

  青木芳尚, 倉千晴, 幅崎浩樹
• 特願2017-21778:酸素発生電極触媒とその利用法  2017年11月20日

  幅崎浩樹, 青木芳尚, Damian Kowalski