研究者データベース

研究者情報

マスター

アカウント(マスター)

  • 氏名

    北野 翔(キタノ シヨウ), キタノ シヨウ

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

  • 2020, エネルギー材料特論, Materials for Energy Conversion and Storage, 修士課程, 総合化学院, エネルギー変換,エネルギー貯蔵,イオン伝導体,水素吸蔵材料,光エネルギー変換
  • 2020, 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
  • 2020, 化学英語, English for Chemistry, 学士課程, 工学部, 化学,英語,単語,表記法
  • 2020, 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)(近畿大学)

プロフィール情報

  • 北野
  • ID各種

    201901001252319028

業績リスト

研究キーワード

  • 電気化学   光触媒   ソルボサーマル合成   ナノシート   金属酸化物   

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 触媒プロセス、資源化学プロセス
  • ナノテク・材料 / エネルギー化学

論文

  • Yoshitaka Aoki, Kentaro Takase, Hisao Kiuchi, Damian Kowalski, Yuki Sato, Hajime Toriumi, Sho Kitano, Hiroki Habazaki
    Journal of the American Chemical Society 2021年04月23日
  • Sho Kitano, Mei Lee Ooi, Tomokazu Yamamoto, Syo Matsumura, Miho Yamauchi
    Bulletin of the Chemical Society of Japan 94 4 1292 - 1299 2021年 
    Electrooxidation of NH has gained extensive attention for energy and environmental applications such as fuel cells and water purification. In this study, carbon-supported simple metal-nanoparticle, binary- and ternary-nanoalloy (NA) catalysts composed of Fe-group elements, i.e., Fe, Co and Ni, were synthesized and their catalytic performance for NH electrooxidation in alkaline media was investigated. Cyclic voltammetry and chronoamperometry revealed that Ni-containing catalysts show appropriate activities for NH electrooxidation and the catalytic performances of Fe-group catalysts depend on affinity between constituent metals and nitrogen. Each Fe-group element exhibited distinctive catalytic features for the NH electrooxidation, i.e., Ni ensured chemical stability, Fe effectively reduced overpotential and Co increased current density. The ternary NA catalyst showed excellent activities due to combination of all the catalytic features and synergetic effects exerted by the alloying. 3 3 3 3
  • 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 
    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.
  • 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.
  • Naohito Yamada, Sho Kitano, Yuya Yato, Damian Kowalski, Yoshitaka Aoki, Hiroki Habazaki
    ACS APPLIED ENERGY MATERIALS 3 12 12316 - 12326 2020年12月 
    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.
  • Ryoya Masuda, Damian Kowalski, Sho Kitano, Yoshitaka Aoki, Taisuke Nozawa, Hiroki Habazaki
    COATINGS 10 11 2020年11月 
    In this study, zinc is anodized at different voltages in 0.1 mol center dot dm(-3) KOH electrolyte to form nanoporous anodic films. Dark-colored anodic films are formed at anodizing voltages <= 6 V, whereas colorless anodic films are developed at voltages >= 7 V. The anodic films formed at all voltages consist of crystalline ZnO, which was identified by X-ray diffraction and Raman spectroscopy. The Raman spectra of the dark-colored anodic films show the enhanced intensity of the LO phonon mode due to electric-field-induced Raman scattering, which may be associated with the presence of metallic Zn nanoparticles in the anodic films. Scanning electron micrographs and transmission electron micrographs of the cross-section of the dark-colored anodized zinc reveal the formation of two-layer porous anodic films with a highly rough metal/film interface. In contrast, nanoporous anodic films of uniform thickness with a relatively flat metal/film interface are formed for the colorless anodized zinc. The transmission electron microscopy (TEM)/energy dispersive X-ray spectroscopy (EDS) analysis suggested the presence of zinc nanoparticles in the dark-colored anodic films. The non-uniform anodizing and the formation of metal-nanoparticle-dispersed porous anodic films cause the formation of dark-colored anodic films on zinc.
  • Takashi Fukushima, Manabu Higashi, Sho Kitano, Takeharu Sugiyama, Miho Yamauchi
    Catalysis Today 351 12 - 20 2020年07月01日 
    Performance of a polymer electrolyte alcohol electrosynthesis cell (PEAEC) using a glycolic acid (GC)/oxalic acid (OX) redox couple was enhanced via the multiscale approach, i.e., increase of reaction rate on an anode by employing nanometer-scale (nanoscale) IrO catalysts and increase of selectivity for GC production via optimization of cell structures, i.e., a millimeter-scale approach. We prepared nanoscale IrO anode catalyst, which is mixture of IrO nanoparticles (d = 3.7 ± 1.8 nm) and their agglomerates (d < 200 nm). The linear sweep voltammetry measurement for water oxidation revealed that the nanoscale IrO catalyst deposited on a porous carbon paper reduces overpotential for water oxidation by 196 mV from that obtained with an anode composed of commercial microscale IrO grans. Furthermore, application of the nanoscale IrO catalyst on porous titanium paper not only improved durability but also doubly enhanced water oxidation performance. We examined various PEAEC architectures composed of the nanoscale IrO applied Ti anode. Both nanometer- and millimeter-scale approaches realized the best PEAEC performance for GC production, i.e., 59.4% of energy conversion efficiency with 97.1% of Faradaic efficiency for the GC production at 1.8 V and 98.9% of conversion for 3 M OX, which is an almost saturated aqueous solution at operating temperature of the PEAEC (60 °C). 2 2 2 2 2 2 2
  • Yuki Sato, Sho Kitano, Damian Kowalski, Yoshitaka Aoki, Naoko Fujiwara, Tsutomu Ioroi, Hiroki Habazaki
    ELECTROCHEMISTRY 88 6 566 - 573 2020年 
    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. (C) The Author(s) 2020. Published by ECSJ.
  • J. F. Cheng, J. Yang, S. Kitano, G. Juhasz, M. Higashi, M. Sadakiyo, K. Kato, S. Yoshioka, T. Sugiyama, M. Yamauchi, N. Nakashima
    ACS Catalysis 9 8 6974 - 6986 2019年08月 [査読有り][通常論文]
     
    Iridium oxide (IrOx)-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrOx-TiO2-Ti (ITOT), with a high concentration of active OH species and mixed valence IrOx on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm(-2)) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm(-2) for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.
  • Hadi Razavi-Khosroshahi, Sara Mohammadzadeh, Mirabbos Hojamberdiev, Sho Kitano, Miho Yamauchi, Masayoshi Fuji
    ADVANCED POWDER TECHNOLOGY 30 7 1290 - 1296 2019年07月 [査読有り][通常論文]
     
    The accumulation of organic pollutants in surface water, groundwater, and even drinking water has raised as a serious issue in recent decades. Semiconductor-based photocatalysis has emerged as a green and sustainable approach to find remediate solutions for environmental and energy issues. However, the fast recombination rate of photogenerated charge carriers reduces the photocatalytic efficiency of photocatalysts. In this study, a hydrothermal synthesis method is proposed for preparing four types of p-n heterojunctions, BiVO4/BiOX (X = F, Cl, Br, I). BiVO4 is an n-type semiconductor and BiOX is a p-type semiconductor. Photocatalytic activity tests showed that the BiVO4/BiOF has the best photocatalytic performance under visible light, and photoluminescence spectra confirmed the lowest recombination rate of photogenerated charge carriers for BiVO4/BiOF as compared with others. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
  • Hadi Razavi-Khosroshahi, Sara Mohammadzadeh, Mirabbos Hojamberdiev, Sho Kitano, Miho Yamauchi, Masayoshi Fuji
    DALTON TRANSACTIONS 48 25 9284 - 9290 2019年07月 [査読有り][通常論文]
     
    Tantalate semiconductors are potential photocatalysts for hydrogen generation via photocatalytic water splitting reaction because the conduction band of tantalates is composed of the tantalum 5d orbital, which is located at a more negative potential than that of the H+/H-2 half reaction, i.e., 0.0 V vs. NHE. Bi3TaO7 is a stable tantalate under acidic or alkaline conditions, with a band gap suitable for visible light absorption. However, the photocatalytic properties of Bi3TaO7 are only reported based on the dye degradation reactions, probably due to the fast electron/hole recombination losses. 2D crystal-like nanosheets with a thickness of a few nanometers show unique features such as high carrier mobility, the quantum Hall effect, high specific surface area, and excellent electrical/thermal conductivity. 2D structures can also enhance the photocatalytic properties because photo-generated charge carriers in nanosheets are less prone to fast recombinations as compared to their bulk counterparts. In this study, nanosheets of Bi3TaO7 are produced by a liquid exfoliation method and the photocatalytic hydrogen generation reaction is investigated for both the as-synthesized Bi3TaO7 nanoparticles and Bi3TaO7 nanosheets.
  • Kulbir Kaur Ghuman, Kota Tozaki, Masaaki Sadakiyo, Sho Kitano, Takashi Oyabe, Miho Yamauchi
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 21 9 5117 - 5122 2019年03月 [査読有り][通常論文]
     
    Despite many advancements, an inexpensive ammonia synthesis catalyst free from hydrogen and nitrogen poisoning, and capable of synthesizing ammonia under mild conditions is still unknown and is long sought-after. Here we present an active nanoalloy catalyst, RuFe, formed by alloying highly active Ru and inexpensive Fe, capable of activating both N-2 and H-2 without blocking the surface active sites and thereby overcoming the major hurdle faced by the current best performing pure metal catalysts. This novel RuFe nanoalloy catalyst operates under milder conditions than the conventional Fe catalyst and is less expensive than the so far best performing Ru-based catalysts providing additional advantages. Most importantly, by integrating theory and experiments, we identified the underlying mechanisms responsible for lower surface poisoning of this catalyst, which will provide directions for fabricating poison-free efficient NH3 synthesis catalysts in future.
  • M. Yamauchi, S. Hata, H. Eguchi, S. Kitano, T. Fukushima, M. Higashi, M. Sadakiyo, K. Kato
    Catalysis Science & Technology 9 23 6561 - 6565 2019年 [査読有り][通常論文]
     
    © 2019 The Royal Society of Chemistry. Ti1-xZrxO2 complex oxide particles with 0.02 ≤ x ≤ 0.1 show superior catalytic performances for the direct power storage into glycolic acid via electroreduction of oxalic acid. The atomic pair distribution function analysis of X-ray total scatterings suggested that structural periodicity is the key factor for the catalytic enhancement.
  • Takashi Fukushima, Sho Kitano, Shinichi Hata, Miho Yamauchi
    Science and Technology of Advanced Materials 19 1 142 - 152 2018年12月31日 [査読有り][通常論文]
     
    We demonstrated carbon-neutral (CN) energy circulation using glycolic acid (GC)/oxalic acid (OX) redox couple. Here, we report fundamental studies on both catalyst search for power generation process, i.e. GC oxidation, and elemental steps for fuel generation process, i.e. OX reduction, in CN cycle. The catalytic activity test on various transition metals revealed that Rh, Pd, Ir, and Pt have preferable features as a catalyst for electrochemical oxidation of GC. A carbon-supported Pt catalyst in alkaline conditions exhibited higher activity, durability, and product selectivity for electrooxidation of GC rather than those in acidic media. The kinetic study on OX reduction clearly indicated that OX reduction undergoes successive two-electron reductions to form GC. Furthermore, application of TiO2 catalysts with large specific area for electrochemical reduction of OX facilitates the selective formation of GC.
  • Miho Yamauchi, Sho Kitano, Masaaki Sadakiyo
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 254 2017年08月 [査読有り][通常論文]
  • Sho Kitano, Masaaki Sadakiyo, Kenichi Kato, Miho Yamauchi, Hiroyuki Asakura, Tsunehiro Tanaka, Keiji Hashimoto, Hiroshi Kominami
    APPLIED CATALYSIS B-ENVIRONMENTAL 205 340 - 346 2017年05月 [査読有り][通常論文]
     
    For a rhodium ion-modified TiO2 (Rh3+/TiO2) photocatalyst responding to visible light, control of the structure of the Rh3+ modifier and effects of the structures of the Rh3+ modifier on photocatalytic activities were examined. A TiO2 support was pre-calcined to maintain crystallinity and specific surface area during post-calcination, and the structure of the Rh3+ modifier for Rh3+/TiO2 was changed by post-calcination without causing changes in the crystallinity and specific surface area of the TiO2 support. In mineralization of acetone under irradiation of visible light, the photocatalytic activities of the post-calcined Rh3+/TiO2 showed a volcano-like tendency as a function of post-calcination temperature. The results of this study showed that an atomically isolated structure of the Rh3+ modifier was preferable for high activities and that aggregation of the Rh species led to a decrease in the activities. (C) 2016 Elsevier B.V. All rights reserved.
  • Sho Kitano, Atsuhiro Tanaka, Keiji Hashimoto, Hiroshi Kominami
    APPLIED CATALYSIS A-GENERAL 521 202 - 207 2016年07月 [査読有り][通常論文]
     
    Metal ion-modified TiO2 photocatalysts designated by combinations of various metal ions and TiO2 powders that respond to visible light and exhibit controllable photocatalytic oxidative performances were examined. The photocatalytic oxidative performances were evaluated by selective oxidation of benzyl alcohol in water in the presence of O-2 under irradiation of visible light. The TiO2 samples modified with Ru3+, Pd2+ and Rh3+ (Ru3+/TiO2, Pd2+/TiO2 and Rh3+/TiO2) exhibited high levels of photocatalytic activity. The effects of metal ions and the kind of TiO2 on photocatalytic performances of Rh3+/TiO2 and Ru3+/TiO2 were investigated in detail. (C) 2015 Elsevier B.V. All rights reserved.
  • Sho Kitano, Miho Yamauchi, Shinichi Hata, Ryota Watanabe, Masaaki Sadakiyo
    GREEN CHEMISTRY 18 13 3700 - 3706 2016年 [査読有り][通常論文]
     
    We demonstrate the production of glycolic acid, an industrially important alcoholic compound, via the electrochemical reduction of oxalic acid, which is procurable from biomass, and electro-oxidation of water with the help of renewable light energy for the first time. In principle, this new synthesis system is achievable while minimizing the consumption of fossil resources. We built a precious-metal free electrosynthesis system by employing a TiO2 cathode for oxalic acid reduction and a WO3 photoanode for water oxidation. The alcohol production proceeds during the application of electric power above 2.1 V in the dark. Notably, UV-visible light irradiation of the WO3 photoanode enables glycolic acid electrosynthesis above 0.5 V, which is lower (by 0.6 V) than the theoretical bias, i.e., 1.1 V. Glycolic acid electrosynthesis with an 80% high Faradaic efficiency was achieved on applying a bias of 1.5 V under UV-visible irradiation (lambda > 300 nm).
  • M. Yamauchi, R. Watanabe, S. Hata, S. Kitano, M. Sadakiyo, T. Takeguchi
    ECS Transactions 75 43 17 - 21 2016年 [査読有り][通常論文]
     
    © The Electrochemical Society. We demonstrated an electric power circulation method that does not emit CO2 and is based on the glycolic acid (GC)/oxalic acid (OX) redox couple. Electric power charge in GC was achieved through OX electro-reduction with high selectivity (>98%) using purely anatase-type Ti02 spheres in the potential region of -0.5 to -0.7 V vs. RHE at 50 °C. We also realized GC production via the combination of electrochemical OX reduction and electro-oxidation of water with the help of renewable light energy for the first time. Furthermore, we succeeded in power generation via the selective electro-oxidation of GC to OX without CO2 emission. These results are the first experimental proof of the carbon-neutral power circulation involving an alcohol/carboxylic acid redox couple.
  • Takeshi Matsumoto, Masaaki Sadakiyo, Mei Lee Ooi, Sho Kitano, Tomokazu Yamamoto, Syo Matsumura, Kenichi Kato, Tatsuya Takeguchi, Miho Yamauchi
    SCIENTIFIC REPORTS 4 2014年07月 [査読有り][通常論文]
     
    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C-2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system.
  • Sho Kitano, Atsuhiro Tanaka, Keiji Hashimoto, Hiroshi Kominami
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 16 24 12554 - 12559 2014年 [査読有り][通常論文]
     
    Photocatalytic oxidation of benzyl alcohols in aqueous suspensions of rhodium ion-modified titanium(IV) oxide (Rh3+/TiO2) in the presence of O-2 under irradiation of visible light was examined. In the photocatalytic oxidation of benzyl alcohol, benzaldehyde was obtained in a high yield (97%) with >99% conversion of benzyl alcohol. Rh3+/TiO2 photocatalysts having various physical properties were prepared using commercially available TiO2 powders as supporting materials for Rh3+ to investigate the effect(s) of physical properties of TiO2 on photocatalytic activities of Rh3+/TiO2 for selective oxidation. Adsorption properties of benzyl alcohol, benzaldehyde and benzoic acid on TiO2 were also investigated to understand the high benzaldehyde selectivity over the Rh3+/ TiO2 photocatalyst. The reaction mechanism was discussed on the basis of the results of photocatalytic oxidation of various p-substituted benzyl alcohol derivatives.
  • Sho Kitano, Naoya Murakami, Teruhisa Ohno, Yasufimi Mitani, Yoshio Nosaka, Hiroyuki Asakura, Kentaro Teramura, Tsunehiro Tanaka, Hiroaki Tada, Keiji Hashimoto, Hiroshi Kominami
    JOURNAL OF PHYSICAL CHEMISTRY C 117 21 11008 - 11016 2013年05月 [査読有り][通常論文]
     
    A rhodium(III) ion (Rh3+)-modified TiO2 (Rh3+/TiO2) photocatalyst, prepared by a simple adsorption method and exhibiting high levels of photocatalytic activity in degradation of organic compounds, was investigated by using X-ray absorption fine structure (XAFS) measurements, (photo)electrochemical measurements, double-beam photoacoustic (DB-PA) spectroscopic measurements, and photoluminescence measurements. Based on the results, the features of the Rh3+ modifier and the working mechanism of the Rh3+/TiO2 photocatalyst are discussed. XAFS measurements revealed that the Rh3+ species were highly dispersed and almost atomically isolated on TiO2. The (photo)electrochemical measurements, DB-PA spectroscopic measurements, and photoluminescence showed a unique bifunction of the Rh3+ modifier as a promoter for O-2 reductions and an electron injector to the conduction band of TiO2 for response to visible light. The reasons for the Rh3+/TiO2 photocatalyst exhibiting higher levels of photocatalytic activity than those of TiO2 photocatalysts modified with other metal ions are also discussed on the basis of obtained results.
  • Sho Kitano, Keiji Hashimoto, Hiroshi Kominami
    CATALYSIS TODAY 164 1 404 - 409 2011年04月 [査読有り][通常論文]
     
    Rhodium(III) ion (Rh3+)-modified TiO2 (Rh3+/TiO2) samples having various physical properties and structures (anatase and rutile) were prepared using commercially available TiO2 samples. Thus-prepared Rh3+/TiO2 samples were used for degradation of acetaldehyde or mineralization of acetone with a constant vapor pressure under irradiation of visible light and correlations between the photocatalytic activities and physical properties were investigated. Rhodium(III) ion on the surface of TiO2 worked as an inorganic photosensitizer and the Rh3+/TiO2 samples showed a kind of volcano-like tendency against specific surface area of TiO2, indicating that the balance of surface area and crystallinity of TiO2 is important in an Rh3+/TiO2 photocatalyst. The latter reaction system was found to be a simple and convenient method to evaluate the activity of a photocatalyst in a short time. The role of Rh3+ as a catalyst for multi-electron reduction of oxygen is discussed on the basis of results obtained for Rh3+-modified rutile-type TiO2 samples. (C) 2010 Elsevier B. V. All rights reserved.
  • Sho Kitano, Keiji Hashimoto, Hiroshi Kominami
    APPLIED CATALYSIS B-ENVIRONMENTAL 101 3-4 206 - 211 2011年01月 [査読有り][通常論文]
     
    Using the adsorption method, small amounts of rhodium ion (Rh3+) or copper ion (Cu2+) were loaded on nanocrystalline titanium(IV) oxide (TiO2) with various physical properties prepared by the HyCOM (hydrothermal crystallization in organic media) method and subsequent calcination at various temperatures. In photocatalytic degradation of 2-propanol under visible light irradiation, Rh3+-modified HyCOM-TiO2 samples exhibited higher levels of activity than did Cu2+-modified HyCOM-TiO2 samples and the nitrogen-doped TiO2 sample. The Rh3+-modified HyCOM-TiO2 samples showed a volcano-like tendency with calcination temperature, suggesting that the balance of surface area and crystallinity of TiO2 is important in an Rh3+/TiO2 photocatalyst. Rutile-type TiO2 modified with Cu-2 exhibited the highest level of activity among the Cu2+/HyCOM-TiO2 samples. (c) 2010 Elsevier B.V. All rights reserved.
  • Sho Kitano, Keiji Hashimoto, Hiroshi Kominami
    CHEMISTRY LETTERS 39 6 627 - 629 2010年06月 [査読有り][通常論文]
     
    Using adsorption method, a small amount of rhodium ion (Rh3+) was loaded on nanocrystalline titanium(IV) oxide (TiO2) with various physical properties prepared by HyCOM and subsequent calcinations at various temperatures. In photocatalytic degradation of 2-propanol under visible light irradiation, Rh3+-modified HyCOM-TiO2 samples exhibited higher levels of activity than did nitrogen-doped TiO2 sample and showed a volcano-like tendency with calcination temperature, suggesting that the balance of surface area and crystallinity of TiO2 is important in an Rh3+/TiO2 photocatalyst.
  • Keiji Hashimoto, Katutoshi Sumida, Sho Kitano, Kazuto Yamamoto, Nobuaki Kondo, Yoshiya Kera, Hiroshi Kominami
    CATALYSIS TODAY 144 1-2 37 - 41 2009年06月 [査読有り][通常論文]
     
    Titanium(IV) oxide samples modified with platinum or rhodium chloride (H2PtCl6/TiO2 or RhCl3/TiO2) were prepared by an impregnation method and post-calcination at various temperatures and were used for photo-oxidation of nitrogen oxide under irradiation of visible light or UV light. Turnover numbers of both the catalysts were maintained at temperatures Lip to 350 degrees C under 24-h irradiation of visible light, although the specific surface area of the catalysts decreased greatly with increase in post-calcination temperature. The turnover number of H2PtCl6/TiO2 was about two-times larger than that of RhCl3/TiO2. Only a small amount of released NO2 was observed in the RhCl3/TiO2 catalyst, whereas in the H2PtCl6/TiO2 catalyst, the amount of NO2 released to gas phase increased with an increase in oxidation products. The small amount of released NO2 indicates that most of the NOx adsorbed on RhCl3/TiO2 as an adsorption form of nonvolatile NO3, whereas the amount of adsorbed NO2 on H2PtCl6/TiO2 was about four-times larger than that on RhCl3/TiO2. The results indicate that the oxidation rate of NO2 to NO3-over RhCl3/TiO2 was faster than that over H2PtCl6/TiO2. These results strongly suggest that the Cl radical induced by visible light was not directly related to the photo-oxidation of NO to NO2 and NO3 and that the complex species of RhCl3 and H2PtCl6 contributed to the photo-oxidation. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

共同研究・競争的資金等の研究課題

  • 単層ナノシート担体を用いた金属クラスター電極触媒の電子状態制御
    日本学術振興会:科学研究費助成事業 若手研究
    研究期間 : 2020年04月 -2022年03月 
    代表者 : 北野 翔
  • 日本学術振興会:科学研究費助成事業 若手研究
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 北野 翔
     
    本研究では、層状複水酸化物(LDH)から剥離した水酸化物ナノシートに金属ナノ粒子を担持することで、酸素発生反応(OER)に高活性な新規電極触媒を合成した。金属ナノ粒子の担持により、2価の金属イオンとしてCo2+, Ni2+を含むLDHナノシートの活性が向上することが分かった。金属ナノ粒子の担持により、OERに有効な電極構造が構築されることに加えて、ナノシートとナノ粒子間における電荷移動によって活性点の電子状態が変化し、反応性が向上することが明らかになった。
  • 可視光応答性を有するボール型チタニアナノバスケットの合成とそれを用いる光触媒反応
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    研究期間 : 2011年 -2013年 
    代表者 : 北野 翔
     
    種々の条件で合成したHyCOM-TiO_2を合成し、溶媒やカップリング剤の種類を変更してバスケット構造の構築を検討したが細孔を有するボール型のナノバスケットは構築されなかった。HyCOM-TiO_2の多くが球状のような微粒子ではなく、ある程度の厚みを有した六角板状の構造であるため、バスケット構造の構築が困難であることが原因であると考えられる。 焼成処理によって表面Rh種の状態を制御した高活性なRh^<3+>/TiO_2を用い、可視光照射下において本課題の反応の一つであるニトロベンゼンの光触媒的還元反応を行った。2-プロパノール溶媒を用いてこの反応を行ったところ、反応の進行が確認され、65%の選択率でアミノベンゼンを得ることに成功した。これは可視光照射下において金属イオン修飾TiO_2光触媒系を用いて還元的有機合成を行った初めての例である。また、この反応系はTiO_2をベースにした可視光応答型光触媒による還元反応であるため、既存の反応系への応用や他反応系との様々な組み合わせが期待できる。 金属イオン修飾TiO_2を用いたアルコールの選択酸化反応において、さらなる反応性の向上のために反応系における基質(ベンジルアルコールとその酸化生成物)の吸着特性の解析を行った。その結果、基質の酸化速度はTiO_2上への吸着量に依存することを見出した。金属イオン修飾TiO_2を用いた本反応系において基質の酸化速度は吸着量によって決定され、アルコールとアルデヒドの吸着量の差が、アルデヒド生成の高い選択性に寄与していることが明らかになった。これらの結果は、TiO_2ベースの光触媒を用いるアルコールの選択酸化反応系において、今後の触媒設計指針に大きく貢献すると考えられる。 総括すると、HyCOM-TiO_2を用いたバスケット構造の構築には至らなかったが、金属イオン修飾物の制御や、ソルボサーマル法によって合成した新規可視光応答型光触媒により、当初の計画以上の反応の多様性を得るとともに、今後の可視光応答型光触媒の発展が期待される結果を得た。


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.