Sep. 2024, The Society of Pure & Applied Coordination Chemistry (SPACC), The SPACC Incentive Award　　　　　　　　　　　　　　　
Development of Noble Metal-Free Electrocatalysts Inspired by Metalloenzymes
Masaru Kato

Jan. 2023, 令和４年度燃料電池開発情報センター(FCDIC) 奨励賞　　　　　　　　　　　　　　　
金属酵素に学ぶ電極触媒の役割と開発
加藤優

Sep. 2022, 2022年度 日本表面真空学会 会誌賞　　　　　　　　　　　　　　　
加藤優;八木一三

Nov. 2020, 日本化学会北海道支部奨励賞　　　　　　　　　　　　　　　
触媒–電極接合界面の設計と高活性電極触媒開発
加藤優

Feb. 2018, Symposium on Nanomaterials for Environmental Purification and Energy Conversion (SNEPEC), Best Poster Award　　　　　　　　　　　　　　　
Incorporation of multinuclear copper active sites into nitrogen-doped carbon for electrochemical oxygen reduction
Masaru Kato

Oct. 2017, International Symposium on Novel Energy Nanomaterials, Catalysts and Surfaces for Future Earth (NENCS) –Material Research, Characterization and Imaging by in situ/Operando XAFS and X-ray Techniques–, NENCS Poster Award (General)　　　　　　　　　　　　　　　
Efficient Electrochemical Oxygen Reduction Catalyzed at Multinuclear Copper Active Sites Incorporated in Nitrogen-Doped Carbon Nanosheets
Masaru Kato

May 2016, The Surface Science Society of Japan, SSSJ Rising-Researcher Lecture Award　　　　　　　　　　　　　　　
カーボン担持銅二核錯体からなる酸素還元電極触媒のin situ XAFS観察
Masaru Kato

Protein Film Electrochemistry and Spectroscopic Measurements of Transmembrane Metalloenzymes
Masaru KATO, Ichizo YAGI
Vacuum and Surface Science, 67, 10, 483, 488, Surface Science Society Japan, 10 Oct. 2024, [Invited], [Lead author, Corresponding author]
Japanese, Research society

Co-presence of PtNi Nanowires and Ionic Liquid in Carbon Mesopores Enhances Electrocatalytic Oxygen Reduction Activity
Yuta Kato, Masaru Kato, Shun Saito, Yu Zhuang, Yoshimi Iguchi, Jun Sato, Tasuku Komanoya, Kentaro Soma, Koshiro Suzuki, Ichizo Yagi
Nanoscale, 16, 20505, 20509, Oct. 2024, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Cu, Fe, N‐doped Carbon Nanotubes Prepared through Silica Coating for Selective Oxygen Reduction to Water in Acidic Media
Masaru Kato, Daiki Abe, Siqi Xie, Shun Sato, Natsuki Fujibayashi, Koki Matsumoto, Akira Onoda, Takashi Hayashi, Takaya Mitsui, Kosuke Fujiwara, Takashi Yamamoto, Yasuaki Einaga, Colin A. Tadgell, Yuta Kato, Kiyotaka Asakura, Ichizo Yagi
ChemCatChem, 16, 15, e202400017, 12 Aug. 2024, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Dependence on the crystallographic orientation of Au single crystal surfaces modified with homocysteine toward enantioselective redox reactions
Sayuki Oka, Masaru Kato, Soichiro Yoshimoto, Ichizo Yagi
Chemistry Letters, 53, 2, upad041, Feb. 2024, [Peer-reviewed]
English, Scientific journal, Effects of enantioselective interactions on redox reactions of chiral molecules were studied using Au single crystal electrodes modified with amino acids. The redox peak current densities of R(+)- or S(−)-N, N-dimethyl-1-ferrocenylethylamine on Au(111) modified with L- or D-homocysteine (L-/D-Hcy) depended on the combination of these chiralities. Hcy/Au(100) showed no dependence on redox peak current densities. The difference in the molecular arrangement of Hcy between Au(111) and Au(100) greatly affects enantioselective redox reactions at the electrode interface.

Platinum–Nickel Alloy Nanowire Electrocatalysts Transform into Pt-Skin Beads-on-Nanowires Keeping Oxygen Reduction Reaction Activity During Potential Cycling
Yu Zhuang, Yoshimi Iguchi, Tianchi Li, Masaru Kato, Yasir Arafat Hutapea, Akari Hayashi, Takeshi Watanabe, Ichizo Yagi
ACS Catalysis, 14, 3, 1750, 1758, American Chemical Society (ACS), 18 Jan. 2024, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Selective electrocatalysis of the nitrous oxide reduction reaction to nitrogen on carbon-supported Pt–Pd–Sn nanoparticles
Abinash Chandro Sarker, Masaru Kato, Mitsuki Kawamura, Takeshi Watanabe, Ichizo Yagi
Catalysis Science & Technology, 14, 15, 4137, 4141, Royal Society of Chemistry (RSC), 2024, [Peer-reviewed], [Corresponding author]
English, Scientific journal, Carbon-supported Pt–Pd–Sn nanoparticles show the electrocatalytic N₂O reduction reaction activity with almost 100% Faradaic efficiency to N₂ at ≥+0.06 V vs. RHE in acidic media under N₂O and high selectivity in the co-presence of O₂.

The pH dependence of the electrocatalytic nitrate reduction by tin-modified palladium(100) electrodes: Effects of structures of tin species and protonation of nitrite
Yang Deng, Masaru Kato, Jinhang Zheng, Chuanping Feng, Ichizo Yagi
Electrochimica Acta, 470, 143301, 143301, Elsevier BV, Dec. 2023, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Improving Oxygen Evolution Reaction Performance and Durability Using Rhombic Dodecahedral PtNiIr Nanoframes with Metal Oxide Supports in Acidic Media
Colin A. Tadgell, Masaru Kato, Keiko Miyabayashi, Ichizo Yagi
ACS Catalysis, 13, 18, 12288, 12298, 05 Sep. 2023, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Composite with a Glassy Nonporous Coordination Polymer Enhances Gas Adsorption Selectivity
Xin Zheng, Masaru Kato, Yohei Uemura, Daiju Matsumura, Ichizo Yagi, Kiyonori Takahashi, Shin-ichiro Noro, Takayoshi Nakamura
Inorganic Chemistry, 62, 3, 1257, 1263, 23 Jan. 2023, [Peer-reviewed]
Scientific journal

金属酵素に学ぶ電極触媒の設計と開発　　　　　　　　　　　　　　　
燃料電池, 23, 1, 49, 57, 2023, [Lead author, Corresponding author]
Japanese, Research society

Effects of Interfacial Interactions on Electrocatalytic Activity of Cytochrome c Oxidase in Biomimetic Lipid Membranes on Gold Electrodes
Masaru Kato, Ryoya Sano, Narumi Yoshida, Masatoshi Iwafuji, Yoshito Nishiyama, Sayuki Oka, Kyoko Shinzawa-Itoh, Yuya Nishida, Yasunori Shintani, Ichizo Yagi
The Journal of Physical Chemistry Letters, 13, 39, 9165, 9170, American Chemical Society (ACS), 06 Oct. 2022, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Electrocatalytic nitrate and nitrous oxide reduction at interfaces between Pt-Pd nanoparticles and fluorine-doped tin oxide
Abinash Chandro Sarker, Masaru Kato, Ichizo Yagi
Electrochimica Acta, 425, 140628, 140628, Elsevier {BV}, Sep. 2022, [Peer-reviewed], [Corresponding author]
English, Scientific journal, We report the preparation of Pt and/or Pd nanoparticle-deposited fluorine-doped tin oxide (FTO) electrodes by an arc-plasma deposition (APD) technique and their electrocatalytic activity for nitrate (NO3–), nitrite (NO2–), nitric oxide (NO), and nitrous oxide (N2O) reduction reactions in acidic media. Cyclic voltammetry of the electrodes revealed that the co-presence of Pt and Pd on FTO showed higher catalytic activity than Pt or Pd on FTO for the NO3– reduction reaction, where the PtPd/Sn interface acts as the catalytic active site. The PtPd/Sn interface also showed higher catalytic activity for the N2O reduction reaction to dinitrogen than the Pt/Sn or Pd/Sn interfaces, whereas it showed no drastic contribution to the electrocatalytic NO2– and NO reduction reactions. Because the NO3– and N2O reduction reaction occur in the potential region of hydrogen adsorption on Pt and Pd electrodes, the PtPd/Sn interface could enhance NO3– and N2O adsorption and/or suppress the hydrogen adsorption. Our findings will be useful for the design of interfaces between noble metal mixture/alloy nanoparticles and Sn, leading to the practical application of denitrification to harmless dinitrogen.

In situ fluorescence yield soft X-ray absorption spectroscopy of electrochemical nickel deposition processes with and without ethylene glycol
Akinobu Yamaguchi, Naoya Akamatsu, Shunya Saegusa, Ryo Nakamura, Yuichi Utsumi, Masaru Kato, Ichizo Yagi, Tomoko Ishihara, Masaki Oura
RSC Advances, 12, 17, 10425, 10430, Apr. 2022, [Peer-reviewed], [Corresponding author]
English, Scientific journal, The electrochemical Ni deposition at a platinum electrode was investigated in a plating nickel bath in the presence and absence of ethylene glycol (EG) using fluorescence yield soft X-ray absorption spectroscopy (FY-XAS) in the Ni L2,3-edge and O K-edge regions under potential control. At ≤+0.35 V vs. the reversible hydrogen electrode (RHE), the electrochemical Ni deposition was detected by the Ni L2,3-edge FY-XAS in the presence of EG whereas almost no such event was observed in the absence of EG. A drastic decrease of FY-XAS intensities in the O K-edge region was also observed in the presence of EG at >+0.35 V vs. RHE, suggesting that the nano-/micro-structured Ni deposition initiated by the removal of water molecules occurs on the Pt electrode. The complex formation of Ni2+ with EG and the adsorption of EG on the Ni surface could play an important role in the Ni deposition. This study demonstrates that the in situ FY-XAS is a powerful and surface-sensitive technique to understand (electro)chemical reactions including polyol synthesis and electrocatalysis at solid-liquid interfaces.

X-ray Absorption Spectroscopy at Platinum Group Metal (PGM) and Non-PGM Electrocatalysts
Masaru KATO, Ichizo YAGI
Denki Kagaku, 90, 1, 16, 20, The Electrochemical Society of Japan, 05 Mar. 2022, [Lead author]
Japanese, Scientific journal

One-Step Preparation of Fe/N/C Single-Atom Catalysts Containing Fe−N4 Sites from an Iron Complex Precursor with 5,6,7,8-Tetraphenyl-1,12-Diazatriphenylene Ligands
Koki Matsumoto, Masaru Kato, Ichizo Yagi, Siqi Xie, Kiyotaka Asakura, Shin-ichiro Noro, Norimitsu Tohnai, Stéphane Campidelli, Takashi Hayashi, Akira Onoda
Chemistry – A European Journal, 28, 5, e202103545, Wiley, 2022, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
English, Scientific journal

Structural Transformation of Pt–Ni Nanowires as Oxygen Reduction Electrocatalysts to Branched Nanostructures during Potential Cycles
Masaru Kato, Yoshimi Iguchi, Tianchi Li, Yuta Kato, Yu Zhuang, Kotaro Higashi, Tomoya Uruga, Takahiro Saida, Keiko Miyabayashi, Ichizo Yagi
ACS Catalysis, 12, 259, 264, American Chemical Society (ACS), 15 Dec. 2021, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We report the preparation, oxygen reduction reaction (ORR) electrocatalytic activity, and structural transformation of Pt-Ni nanowires (NWs) during potential cycles in the presence and absence of Pt-Ni nanoparticles (NPs). The ORR activity of NWs increases over 25000 potential cycles in the presence of NPs, involving the structural transformation of NWs to branched nanostructures assisted by Ostwald ripening of NPs. This structural transformation is coupled with the surface electronic structural change, as confirmed by in situ X-ray absorption spectroscopy and carbon monoxide stripping voltammetry, leading to catalytic activity improvement and Pt dissolution suppression. Although a similar structural transformation was also observed even in the absence of NPs, greater amounts of Pt were dissolved during potential cycles. These results indicate that the structural transformation is intrinsic to Pt-based NWs but the structural transformation of NWs assisted by Ostwald ripening of NPs is beneficial to suppress the Pt dissolution. The concept of the structural optimization of nanostructured catalysts assisted by Ostwald ripening of NPs under potential cycles will guide us to develop highly active and durable Pt-based electrocatalysts and phase-engineered nanomaterials.

Electrocatalytic activity and volatile product selectivity for nitrate reduction at tin-modified Pt(100), Pd(100) and Pd–Pt(100) single crystal electrodes in acidic media
Masaru Kato, Yuki Unuma, Manabu Okui, Yunteng Qu, Jinhang Zheng, Satoshi Taguchi, Fumiya Kiguchi, Mashu Torihata, Yunzhi Gao, Nagahiro Hoshi, Ichizo Yagi
Electrochimica Acta, 139281, 139281, Elsevier {BV}, Dec. 2021, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Electrochemically Driven Specific Alkaline Metal Cation Adsorption on a Graphene Interface
Satoshi Yasuda, Kazuhisa Tamura, Masaru Kato, Hidehito Asaoka, Ichizo Yagi
The Journal of Physical Chemistry C, 125, 22154, 22162, American Chemical Society (ACS), 04 Oct. 2021, [Peer-reviewed]
Scientific journal

Impact of membrane protein-lipid interactions on formation of bilayer lipid membranes on SAM-modified gold electrode
Masaru Kato, Yuya Masuda, Narumi Yoshida, Takehiko Tosha, Yoshitsugu Shiro, Ichizo Yagi
Electrochimica Acta, 373, 137888, 137888, Elsevier BV, Mar. 2021, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Impact of Heterometallic Cooperativity of Iron and Copper Active Sites on Electrocatalytic Oxygen Reduction Kinetics
Masaru Kato, Natsuki Fujibayashi, Daiki Abe, Naohiro Matsubara, Satoshi Yasuda, Ichizo Yagi
ACS Catalysis, 11, 2356, 2365, American Chemical Society ({ACS}), 19 Feb. 2021, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Terahertz Raman Spectroscopy of Ligand-Protected Au8 Clusters
Masaru Kato, Yukatsu Shichibu, Kazuya Ogura, Mitsuhiro Iwasaki, Mizuho Sugiuchi, Katsuaki Konishi, Ichizo Yagi
The Journal of Physical Chemistry Letters, 11, 19, 7996, 8001, American Chemical Society ({ACS}), 01 Oct. 2020, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Electronic Effects of Nitrogen Atoms of Supports on Pt–Ni Rhombic Dodecahedral Nanoframes for Oxygen Reduction
Masaru Kato, Ryota Nakahoshiba, Kazuya Ogura, Shoichi Tokuda, Satoshi Yasuda, Kotaro Higashi, Tomoya Uruga, Yohei Uemura, Ichizo Yagi
ACS Applied Energy Materials, 3, 7, 6768, 6774, American Chemical Society ({ACS}), 27 Jul. 2020, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal, Pt-based nanostructures immobilized on carbon supports have been widely used as electrocatalysts. Their catalytic activity can be improved by support modification including nitrogen doping and coating with nitrogen-containing polymers, where nitrogen atoms possibly interact with surface Pt atoms at a catalyst/support interface. To understand electronic effects of nitrogen-doped and polymer-coated carbon supports on the catalytic activity of Pt-based nanostructured catalysts, we prepared Pt3Ni nanoframes (NFs) supported on polybenzimidazole (PBI)-coated and uncoated carbon nanotubes for the oxygen reduction reaction (ORR), and then compared their catalytic activities and electronic properties with those of NFs immobilized on nitrogen-doped and undoped carbon supports. Although both PBI-coating and nitrogen-doping approaches improved the catalytic activity of NFs, ex situ X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy revealed that nitrogen doping showed electronic effects on NFs, whereas PBI-coating showed almost no impact on the electronic state of NFs but stabilized Pt(OH)ad species under electrochemical conditions. Our studies demonstrate that difference in microscopic environments of nitrogen atoms at the catalyst/support interface is highly sensitive to the electronic effects of supports on Pt-based electrocatalysts.

Electrocatalytic Oxygen Reduction at Multinuclear Metal Active Sites Inspired by Metalloenzymes
Masaru Kato, Ichizo Yagi
e-Journal of Surface Science and Nanotechnology, 18, 81, 93, SURFACE SCI SOC JAPAN, 14 Mar. 2020, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Polymer electrolyte fuel cells (PEFCs) are a clean, sustainable device to convert chemical energy to electricity and can provide power for automobiles, trains, and ships. In PEFCs, the oxygen reduction reaction (ORR) occurs at the cathode and is catalyzed at electrocatalysts. The activity of ORR electrocatalysts is known to limit the overall performance of PEFCs because the ORR is more sluggish than the hydrogen oxidation reaction at the anode. In the state-of-the-art PEFC, platinum group metal (PGM)-based ORR electrocatalysts are used. Since PGMs are rare and expensive, highly active and durable non-PGM ORR electrocatalysts are required for widespread applications of PEFCs. In nature, metalloenzymes such as cytochrome c oxidase and multicopper oxidases efficiently catalyze the ORR and utilize multinuclear iron and/or copper complexes as active sites. The structure of these active sites and enzyme reaction mechanisms would give us design concepts of artificial non-PGM electrocatalysts for the ORR, possibly leading us to develop next-generation non-PGM electrocatalysts. Herein, recent research progress on understanding enzymatic ORR reaction mechanisms and developing non-PGM ORR electrocatalysts is reviewed from the viewpoint of bio-inspired approaches.

Confinement of Hydrogen Molecules at Graphene–Metal Interface by Electrochemical Hydrogen Evolution Reaction
Satoshi Yasuda, Kazuhisa Tamura, Tomo-o Terasawa, Masahiro Yano, Hideaki Nakajima, Takahiro Morimoto, Toshiya Okazaki, Ryuushi Agari, Yasufumi Takahashi, Masaru Kato, Ichizo Yagi, Hidehito Asaoka
The Journal of Physical Chemistry C, 124, 9, 5300, 5307, American Chemical Society ({ACS}), 05 Mar. 2020, [Peer-reviewed]
English, Scientific journal, Confinement of hydrogen molecules at graphene-substrate interface has presented significant importance from the viewpoints of development of fundamental understanding of two-dimensional material interface and energy storage system. In this study, we investigate H-2 confinement at a graphene-Au interface by combining selective proton permeability of graphene and the electrochemical hydrogen evolution reaction (electrochemical HER) method. After HER on a graphene/Au electrode in protonic acidic solution, scanning tunneling microscopy finds that H-2 nanobubble structures can be produced between graphene and the Au surface. Defect dependence of the bubble formation suggests that intrinsic defects in graphene, which have high hydrogen permeation barrier but are permeable for protons, are involved in the fundamental mechanism of bubble formation. Strain analysis by Raman spectroscopy also shows that atomic size roughness on the graphene/Au surface originating from the HER-induced strain relaxation of graphene plays significant role in formation of the nucleation site and H-2 storage capacity. The result presented herein would provide further understanding of molecular confinement at graphene-based interface and development of novel energy material.

Real-Time Monitoring of Low Pressure Oxygen Molecules over Wide Temperature Range: Feasibility of Ultrathin Hybrid Films of Iridium(III) Complexes and Clay Nanosheets　　　　　　　　　　　　　　　
Hisako Sato, Kazuyoshi Takimoto, Masaru Kato, Shin-ichi Nagaoka, Kenji Tamura, Akihiko Yamagishi
Bull. Chem. Soc. Jpn., 93, doi:10.1246/bcsj.20190277, 194, 199, 2020, [Peer-reviewed]
English, Scientific journal

Host–guest chemistry between cyclodextrin and a hydrogen evolution catalyst cobaloxime
Masaru Kato, Keita Kon, Jun Hirayama, Ichizo Yagi
New Journal of Chemistry, 43, 25, 10087, 10092, Royal Society of Chemistry ({RSC}), 2019, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Cathodic Arc-plasma Deposition of Platinum Nanoparticles on Fluorine-doped Tin Oxide for Electrocatalytic Nitrate Reduction Reaction
Masaru Kato, Ai Araki, Yuki Hara, Satoshi Taguchi, Ichizo Yagi
Electrochemistry, 86, 5, 220, 222, Aug. 2018, [Peer-reviewed], [Lead author]
English, Scientific journal

Surface-Enhanced Infrared Absorption Spectroscopy of Bacterial Nitric Oxide Reductase under Electrochemical Control Using a Vibrational Probe of Carbon Monoxide
Masaru Kato, Shogo Nakagawa, Takehiko Tosha, Yoshitsugu Shiro, Yuya Masuda, Kou Nakata, Ichizo Yagi
The Journal of Physical Chemistry Letters, 9, 5195, 5200, American Chemical Society ({ACS}), Aug. 2018, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Enhancement of Electrocatalytic Oxygen Reduction Activity and Durability of Pt–Ni Rhombic Dodecahedral Nanoframes by Anchoring to Nitrogen-Doped Carbon Support
Masaru Kato, Kazuya Ogura, Shogo Nakagawa, Shoichi Tokuda, Kiyonori Takahashi, Takayoshi Nakamura, Ichizo Yagi
ACS Omega, 3, 8, 9052, 9059, AMER CHEMICAL SOC, Aug. 2018, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Pt-based nanostructured electrocatalysts supported on carbon black have been widely studied for the oxygen reduction reaction (ORR), which occurs at the cathode in polymer electrolyte fuel cells. Because sluggish ORR kinetics are known to govern the cell performance, there is a need to develop highly active and durable electrocatalysts. The ORR activity of Pt-based electrocatalysts can be improved by controlling their morphology and alloying Pt with transition metals such as Ni. Improving the catalyst durability remains challenging and there is a lack of catalyst design concepts and synthetic strategies. We report the enhancement of the ORR activity and durability of a nanostructured Pt-Ni electrocatalyst by strong metal/support interactions with a nitrogen-doped carbon (NC) support. Pt-Ni rhombic dodecahedral nanoframes (NFs) were immobilized on the NC support and showed higher ORR electrocatalytic activity and durability in acidic media than that supported on a nondoped carbon black. Durability tests demonstrated that NF/NC showed almost no activity loss even after 50 000 potential cycles under catalytic conditions, and the Ni dissolution from the NFs was suppressed at the NC support, as confirmed by, energy dispersive X-ray spectroscopy analysis. Physicochemical measurements including surface-enhanced infrared absorption spectroscopy of surface-adsorbed CO revealed that the strong metal/support interactions of the NF with the NC support caused the downshift of the d-band center position of the surface Pt. Our findings demonstrate that tuning the electronic structure of nanostructured Pt alloy electrocatalysts via the strong metal/support interactions with heteroatom-doped carbon supports will allow the development of highly active and robust electrocatalysts.

Incorporation of Multinuclear Copper Active Sites into Nitrogen-Doped Graphene for Electrochemical Oxygen Reduction
Masaru Kato, Marika Muto, Naohiro Matsubara, Yohei Uemura, Yuki Wakisaka, Tsubasa Yoneuchi, Daiju Matsumura, Tomoko Ishihara, Takashi Tokushima, Shin-ichiro Noro, Satoru Takakusagi, Kiyotaka Asakura, Ichizo Yagi
ACS Applied Energy Materials, 1, 5, 2358, 2364, American Chemical Society ({ACS}), May 2018, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Multinuclear metal active sites are widely used as catalytic reaction centers in metalloenzymes and generally show high catalytic activity. For example, laccases are known to catalyze the oxygen reduction reaction (ORR) to water at a multinuclear copper site with almost no energy loss. The ORR is an important reaction not only in oxygenic respiration but also in future energy generation devices such as polymer electrolyte fuel cells and metal-air batteries. For large-scale commercialization of these devices, there is a need to develop highly active ORR electrocatalysts based on nonprecious metals. Incorporation of multinuclear metal active sites in conductive materials such as carbon will allow us to develop highly active electrocatalysts like metalloenzymes. However, such methods had not been established yet. Herein, we report a copper-based ORR electrocatalyst with multinuclear copper active sites in nitrogen-doped graphene. The electrocatalyst was synthesized from the mixture of graphene oxide and a multinuclear copper complex in a short-period heating method. Electrochemical measurements revealed that the obtained electrocatalyst showed the highest electrocatalytic activity for the ORR in the Cu-based electrocatalysts in neutral aqueous solution. Physicochemical measurements including in situ X-ray absorption spectroscopy revealed the incorporation of multinuclear copper sites. Our synthetic approach will offer guidance for developing highly active electrocatalysts utilizing multinuclear metal sites not only for the ORR but also for other electrocatalytic reactions.

表面増強赤外吸収分光法による電極／溶液界面における反応計測　　　　　　　　　　　　　　　
八木一三, 加藤優, 中田耕, 中川省吾
分光研究, 67, 2, 41, 56, Apr. 2018, [Peer-reviewed]
Japanese

Bio-inorganic hybrid photoanodes of photosystem II and ferricyanide-intercalated layered double hydroxide for visible-light-driven water oxidation
Masaru Kato, Hisako Sato, Ichizo Yagi, Miwa Sugiura
Electrochimica Acta, 264, 386, 392, Elsevier Ltd, 20 Feb. 2018, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Photosynthesis converts solar energy into chemical energy. Photosystem II (PSII) oxidizes water to produce oxygen, electrons and protons under solar light irradiation. This light-driven water oxidation initiates a series of reactions in photosynthesis. Basic photoelectrochemical studies on PSII are directed toward the enzymatic applications of PSII for sustainable production of electricity or solar fuels. To maximize the photoelectrochemical catalytic activity of PSII on electrode substrates, interfacial designs between PSII and electrode substrates are important. Herein, we report bio-inorganic photoanodes of PSII and ferricyanide-intercalated layered double hydroxide (LDH) for visible-light-driven water oxidation. PSII is simply drop-cast onto a ferricyanide-intercalated cobalt–aluminum LDH and then shows a turnover frequency of 0.5 ± 0.1 s−1 and a turnover number of 920 ± 40 for 1 h at pH 6.5 at +0.5 V vs. NHE under visible light irradiation. Photoelectrochemical experiments using a PSII inhibitor or a bio-engineered PSII suggest that interfacial electron transfer from the plastoquinone QA site of PSII to ferricyanide may play an important role in improving the photo-electrocatalytic activity and stability of PSII. Our studies will open up new possibilities in fundamental or advanced photoelectrochemical studies of PSII.

Development of a spectro-electrochemical cell for soft X-ray photon-in photon-out spectroscopy
Tomoko Ishihara, Takashi Tokushima, Yuka Horikawa, Masaru Kato, Ichizo Yagi
REVIEW OF SCIENTIFIC INSTRUMENTS, 88, 10, 104101, AMER INST PHYSICS, Oct. 2017, [Peer-reviewed]
English, Scientific journal, We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag vertical bar AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation. Published by AIP Publishing.

Electrocatalytic nitrate reduction on well-defined surfaces of tin-modified platinum, palladium and platinum-palladium single crystalline electrodes in acidic and neutral media
Masaru Kato, Manabu Okui, Satoshi Taguchi, Ichizo Yagi
JOURNAL OF ELECTROANALYTICAL CHEMISTRY, 800, 46, 53, ELSEVIER SCIENCE SA, Sep. 2017, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Nitrate anion is one of the main nitrogen-containing-pollutants in groundwater and can be removed" using denitrification systems including electrocatalytic systems. Herein we report on electrocatalytic nitrate reduction catalyzed on tin-modified single crystalline electrodes of palladium, platinum and palladium-platinum alloy in acidic and neutral media. We have prepared electrodes with the (111) surface or the (100) surface and modified their surface with tin. Cyclic voltammetry of the electrodes has revealed that the tin-modified alloy (trimetallic) electrodes show higher electrocatalytic activity than the tin-modified platinum or palladium (bimetallic) electrodes, and the catalytic reaction is more efficiently catalyzed on the (100) surface rather than the (111) surface. The tin-modified PdPt(100) electrode shows the highest catalytic activity in acidic media as well as in neutral media. X-ray photoelectron spectroscopy suggests that metallic tin forms on the (100) surface, but divalent tin species on the (111) surface, indicating that a surface alloy of tin may form on the (100) surface, resulting in enhancement of the electrocatalytic activity. Our findings suggest that design and preparation of ternary metallic electrodes with the (100) surface will pave the way to the development of practical systems on electrocatalytic denitrification. (C) 2017 Elsevier B.V. All rights reserved.

Bioinspired Iron- and Copper-incorporated Carbon Electrocatalysts for Oxygen Reduction Reaction
Masaru Kato, Takeshi Murotani, Ichizo Yagi
CHEMISTRY LETTERS, 45, 10, 1213, 1215, CHEMICAL SOC JAPAN, Oct. 2016, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We report an Fe/Cu/N-doped carbon electrocatalyst for the oxygen reduction reaction to water. Pyrolysis of metal precursors supported on oxidized carbon black provides the electrocatalyst with high catalytic activity and selectivity. Detailed physical-chemical studies have revealed that the. copresence of iron and copper catalytic sites in carbon in a 1:1 mole ratio, which is the same as that of an enzyme of cytochrome c oxidase, might be the key to synthesize highly active and selective electrocatalysts.

Oxygen Reduction Reaction Catalyzed by Self-Assembled Monolayers of Copper-Based Electrocatalysts on a Polycrystalline Gold Surface
Masaru Kato, Nobuhisa Oyaizu, Katsuaki Shimazu, Ichizo Yagi
JOURNAL OF PHYSICAL CHEMISTRY C, 120, 29, 15814, 15822, AMER CHEMICAL SOC, Jul. 2016, [Peer-reviewed], [Invited], [Lead author]
English, Scientific journal, We report two-dimensional model systems to study the electrocatalytic activities of dinuclear copper complexes for various electrocatalytic reactions including the oxygen reduction reaction (ORR), where we can use electrochemical techniques as well as surface-sensitive techniques such as X-ray photoelectron spectroscopy and vibrational sum frequency generation spectroscopy. Heteroaromatic thiols, including four triazoles and a thiadiazole, are used as metal ligands as well as anchors to a polycrystalline gold electrode. The thiols are self-assembled on the polycrystalline gold electrode and then react with copper(II) ions to give monolayers of copper-based ORR catalysts on the surface. The dinuclear copper complexes of 1,2,4-triazole-3-thiol and 3-amino-1,2,4-triazole-5-thiol show ORR activity and pH-dependent catalytic behavior similar to that of counterparts supported on carbon black, suggesting that our two-dimensional systems can serve as model catalysts for carbon-supported molecular catalysts. We have also self-assembled dinuclear copper complexes with long alkyl or perfluoroalkyl chains on the surface and studied their orientation on the surface and oxygen transport.

Deprotonation of a dinuclear copper complex of 3,5-diamino-1,2,4-triazole for high oxygen reduction activity
Masaru Kato, Ken'ichi Kimijima, Mari Shibata, Hideo Notsu, Kazuya Ogino, Kiyoshi Inokuma, Narumi Ohta, Hiromitsu Uehara, Yohei Uemura, Nobuhisa Oyaizu, Tadashi Ohba, Satoru Takakusagi, Kiyotaka Asakura, Ichizo Yagi
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17, 14, 8638, 8641, ROYAL SOC CHEMISTRY, 2015, [Peer-reviewed], [Lead author]
English, Scientific journal, A dinuclear copper(II) complex of 3,5-diamino-1,2,4-triazole is one of the highly active copper-based catalysts for the oxygen reduction reaction (ORR) in basic solutions. Our in situ X-ray absorption near edge structure measurements revealed that deprotonation of the triazole ligand might cause coordination geometrical changes, resulting in the enhancement of the ORR activity.

Energy transfer in hybrid Langmuir-Blodgett films of iridium complexes and synthetic saponite: dependence of transfer efficiency on the interlayer distance
Hisako Sato, Miwa Ochi, Masaru Kato, Kenji Tamura, Akihiko Yamagishi
NEW JOURNAL OF CHEMISTRY, 38, 12, 5715, 5720, ROYAL SOC CHEMISTRY, Dec. 2014, [Peer-reviewed]
English, Scientific journal, Multi-layered hybrid films comprised of amphiphilic cationic iridium(III) complexes and the exfoliated layers of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Two iridium(III) complexes, [Ir(dfppy)(2)(dc9bpy)](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) and [Ir(dfppy)(2)(dc9bpy)(+) (piqH = 1-phenyisoquinoline), were used as blue (donor) and red emitters (acceptor), respectively. A non-luminescent hybrid layer of stearylammonium and synthetic saponite was deposited in a layer-by-layer manner to vary the distance between the donor and acceptor layers. Energy transfer was analysed according to the Forster-type mechanism with a focus on the dependence of its efficiency on the interlayer distance.

Protein film photoelectrochemistry of the water oxidation enzyme photosystem II
Masaru Kato, Jenny Z. Zhang, Nicholas Paul, Erwin Reisner
CHEMICAL SOCIETY REVIEWS, 43, 18, 6485, 6497, ROYAL SOC CHEMISTRY, Sep. 2014, [Peer-reviewed], [Lead author]
English, Photosynthesis is responsible for the sunlight-powered conversion of carbon dioxide and water into chemical energy in the form of carbohydrates and the release of O-2 as a by-product. Although many proteins are involved in photosynthesis, the fascinating machinery of Photosystem II (PSII) is at the heart of this process. This tutorial review describes an emerging technique named protein film photoelectrochemistry (PF-PEC), which allows for the light-dependent activity of PSII adsorbed onto an electrode surface to be studied. The technique is straightforward to use, does not require highly specialised and/or expensive equipment, is highly selective for the active fractions of the adsorbed enzyme, and requires a small amount of enzyme sample. The use of PF-PEC to study PSII can yield insights into its activity, stability, quantum yields, redox behaviour, and interfacial electron transfer pathways. It can also be used in PSII inhibition studies and chemical screening, which may prove useful in the development of biosensors. PSII PF-PEC cells also serve as proof-of-principle solar water oxidation systems; here, a comparison is made against PSII-inspired synthetic photocatalysts and materials for artificial photosynthesis.

Lattice Water-Induced Helical Stacking of Tartrate-Bridged Dinuclear Palladium(II) Complexes: The Role of Hydrogen Bonding
Keiji Ohno, Tomoaki Sugaya, Masaru Kato, Noriko Matsumoto, Ryoko Fukano, Yasuyo Ogino, Sumio Kaizaki, Takashi Fujihara, Akira Nagasawa
CRYSTAL GROWTH & DESIGN, 14, 8, 3675, 3679, AMER CHEMICAL SOC, Aug. 2014, [Peer-reviewed]
English, Scientific journal, Hydrous crystals of [{Pd-II(bpy)}(2)(mu-x-tart)]. nH(2)O (bpy: 2,2'-bipyridine; tartH(2)(2-): tartrate; 1a: x = L, n = 6; 2a: x = D, n = 6; 3a: x = DL, n = 4; 4a: x = meso, n = 4) and anhydrous crystals of [{Pd-II(bpy)}(2)(mu-L-tart)] (1b) were isolated from aqueous and MeOH solutions, respectively. X-ray crystallography revealed the stacked structures of clamshell-like dinuclear units in 1a-3a and 1b, where intramolecular metal metal and pi-pi stacking interactions were observed. Right- and left-handed helically stacked columns were formed in the 1a and 2a crystals, respectively. The significant role of hydrogen bonding among lattice water molecules and tartrate is suggested because 1b exhibited a zigzag arrangement only through intermolecular metal-metal interactions. In 3a, L- and D-tart units stacked alternately in a zigzag arrangement with intermolecular pi-pi interactions. In 4a, dimeric aggregates of the twisted dinuclear units further formed a 2D sheet architecture.

Comparison of photoelectrochemical water oxidation activity of a synthetic photocatalyst system with photosystem II
Yi-Hsuan Lai, Masaru Kato, Dirk Mersch, Erwin Reisner
FARADAY DISCUSSIONS, 176, 199, 211, ROYAL SOC CHEMISTRY, 2014, [Peer-reviewed]
English, Scientific journal, This discussion describes a direct comparison of photoelectrochemical (PEC) water oxidation activity between a photosystem II (PSII)-functionalised photoanode and a synthetic nanocomposite photoanode. The semi-biological photoanode is composed of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus on a mesoporous indium tin oxide electrode (mesoITO| PSII). PSII embeds all of the required functionalities for light absorption, charge separation and water oxidation and ITO serves solely as the electron collector. The synthetic photoanode consists of a TiO2 and NiOx coated nanosheet-structured WO3 electrode (nanoWO(3)|TiO2|NiOx). The composite structure of the synthetic electrode allows mimicry of the functional key features in PSII: visible light is absorbed by WO3, TiO2 serves as a protection and charge separation layer and NiOx serves as the water oxidation electrocatalyst. MesoITO|PSII uses low energy red light, whereas nanoWO(3)|TiO2|NiOx requires high energy photons of blue-end visible and UV regions to oxidise water. The electrodes have a comparable onset potential at approximately 0.6 V vs. reversible hydrogen electrode (RHE). MesoITO|PSII reaches its saturation photocurrent at 0.84 V vs. RHE, whereas nanoWO(3)|TiO2|NiOx requires more than 1.34 V vs. RHE. This suggests that mesoITO|PSII suffers from fewer limitations from charge recombination and slow water oxidation catalysis than the synthetic electrode. MesoITO|PSII displays a higher 'per active' site activity, but is less photostable and displays a much lower photocurrent per geometrical surface area and incident photon to current conversion efficiency (IPCE) than nanoWO(3)|TiO2|NiOx.

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes
Masaru Kato, Kei Unoura, Toshiyuki Takayanagi, Yasuhisa Ikeda, Takashi Fujihara, Akira Nagasawa
INORGANIC CHEMISTRY, 52, 23, 13375, 13383, AMER CHEMICAL SOC, Dec. 2013, [Peer-reviewed], [Lead author]
English, Scientific journal, Five metal complexes of 2-methylisothiazol-3(2H)-one (MIO), [Co-III(NH3)(5)(MIO)](3+), [Ru-II(NH3)(5)(MIO)](2+), [Ru-III(NH3)(5)(MIO)](3+), [ (PtCl3)-Cl-II(MIO)](-), and trans-[ (UO2)-O-VI(NO3)(2)(MIO)(2)], were synthesized, and their structures were determined by single-crystal X-ray crystallography. MIO is an ambidentate ligand and coordinates to metal centers through its oxygen atom in the cobalt(III), ruthenium(III), and uranium(VI) complexes and through its sulfur atom in the ruthenium(II) and platinum(III) complexes. This result suggests that MIO shows preferential behavior on its donating atoms. We also studied the electron-donor abilities of the oxygen and sulfur atoms of MIO. Various physical measurements on the conjugate acid of MIO and the MIO complexes allowed us to determine an acid dissociation constant (pK(a)) and donor number (DN) for the oxygen atom of MIO and Lever's electrochemical parameter (E-L) and a relative covalency parameter (k(L)) for the sulfur atom.

Covalent Immobilization of Oriented Photosystem II on a Nanostructured Electrode for Solar Water Oxidation
Masaru Kato, Tanai Cardona, A. William Rutherford, Erwin Reisner
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 135, 29, 10610, 10613, AMER CHEMICAL SOC, Jul. 2013, [Peer-reviewed], [Lead author]
English, Scientific journal, Photosystem II (PSII) offers a biological and sustainable route of photochemical water oxidation to O-2 and can provide protons and electrons for the generation of solar fuels, such as H-2. We present a rational strategy to electrostatically improve the orientation of PSII from a thermophilic cyanobacterium, Thermosynechococcus elongatus, on a nanostructured indium tin oxide (ITO) electrode and to covalently immobilize PSII on the electrode. The ITO electrode was modified with a self-assembled monolayer (SAM) of phosphonic acid ITO linkers with a dangling carboxylate moiety. The negatively charged carboxylate attracts the positive dipole on the electron acceptor side of PSII via Coulomb interactions. Covalent attachment of PSII in its electrostatically improved orientation to the SAM-modified ITO electrode was accomplished via an amide bond to further enhance red-light-driven, direct electron transfer and stability of the PSII hybrid photoelectrode.

Electron Transfer in Dye-Sensitised Semiconductors Modified with Molecular Cobalt Catalysts: Photoreduction of Aqueous Protons
Fezile Lakadamyali, Anna Reynal, Masaru Kato, James R. Durrant, Erwin Reisner
CHEMISTRY-A EUROPEAN JOURNAL, 18, 48, 15464, 15475, WILEY-V C H VERLAG GMBH, Nov. 2012, [Peer-reviewed]
English, A visible-light driven H2 evolution system comprising of a RuII dye (RuP) and CoIII proton reduction catalysts (CoP) immobilised on TiO2 nanoparticles and mesoporous films is presented. The heterogeneous system evolves H2 efficiently during visible-light irradiation in a pH-neutral aqueous solution at 25 degrees C in the presence of a hole scavenger. Photodegradation of the self-assembled system occurs at the ligand framework of CoP, which can be readily repaired by addition of fresh ligand, resulting in turnover numbers above 300 molH2 (molCoP)-1 and above 200,000 molH2 (molTiO2 nanoparticles)-1 in water. Our studies support that a molecular Co species, rather than metallic Co or a Co-oxide precipitate, is responsible for H2 formation on TiO2. Electron transfer in this system was studied by transient absorption spectroscopy and time-correlated single photon counting techniques. Essentially quantitative electron injection takes place from RuP into TiO2 in approximately 180 ps. Thereby, upon dye regeneration by the sacrificial electron donor, a long-lived TiO2 conduction band electron is formed with a half-lifetime of approximately 0.8 s. Electron transfer from the TiO2 conduction band to the CoP catalysts occurs quantitatively on a 10 mu s timescale and is about a hundred times faster than charge-recombination with the oxidised RuP. This study provides a benchmark for future investigations in photocatalytic fuel generation with molecular catalysts integrated in semiconductors.

Photoelectrochemical Water Oxidation with Photosystem II Integrated in a Mesoporous; Indium Tin Oxide Electrode
Masaru Kato, Tanai Cardona, A. William Rutherford, Erwin Reisner
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 134, 20, 8332, 8335, AMER CHEMICAL SOC, May 2012, [Peer-reviewed], [Lead author]
English, Scientific journal, We report on a hybrid photoanode for water oxidation consisting of a cyanobacterial photosystem II (PSII) from Thermosynechococcus elongatus on a mesoporous indium-tin oxide (mesoITO) electrode. The three-dimensional metal oxide environment allows for high protein coverage (26 times an ideal monolayer coverage) and direct (mediator-free) electron transfer from PSII to mesoITO. The oxidation of water occurs with 1.6 +/- 0.3 mu A cm(-2) and a corresponding turnover frequency of approximately 0.18 +/- 0.04 (mol O-2) (mol PSII)(-1) s(-1) during red light irradiation. Mechanistic studies are consistent with interfacial electron transfer occurring not only from the terminal quinone Q(B), but also from the quinone Q(A) through an unnatural electron transfer pathway to the ITO surface.

Colloidal metal oxide particles loaded with synthetic catalysts for solar H-2 production
Fezile Lakadamyali, Masaru Kato, Erwin Reisner
FARADAY DISCUSSIONS, 155, 191, 205, ROYAL SOC CHEMISTRY, 2012, [Peer-reviewed]
English, Scientific journal, This discussion describes a study of a particulate semiconductor assembly consisting of a photoactive ruthenium dye-sensitised metal oxide nanoparticle loaded with a synthetic cobaloxime proton reduction catalyst (CoP). The colloidal system evolves H-2 during visible light illumination in pH neutral aqueous solution in the presence of a sacrificial electron donor. The ruthenium photosensitiser (RuP) to cobaloxime loading ratio is simple to vary and optimise and a range of metal oxide nanoparticles were tested. A maximum photoactivity was identified with TiO2 nanoparticles modified with CoP and RuP in a 2 : 1 ratio in the colloidal reaction mixture: visible light irradiation yielded 600 +/- 32 mmol H-2 h(-1) (g TiO2)(-1). A total turnover number of 108 +/- 9 mol H-2 (mol CoP)(-1), the evolution of 4340 +/- 240 mu mol H-2 (g TiO2)(-1) and approximately 87 mu mol H-2 (m(2) TiO2)(-1) were observed after 10 h irradiation. Linkage of the catalysts to TiO2 is critical for the system to work efficiently, and CoP and RuP contain one and two phosphonic acid linker moieties, respectively. The novel phosphonate ester analogue of CoP, [CoCl(dimethylglyoximato)(2)(diethyl pyridyl-4-phosphonate)] (1) was also synthesised and studied. Complex 1 adsorbs only to a small extent to TiO2 and a reduced H-2 production rate (182 +/- 8 mmol H-2 h(-1) (g TiO2)(-1)) was observed when 1 was irradiated with RuP-modified TiO2. Thus, the lower TiO2 affinity of 1 results in a reduced photoactivity of the dispersion. The described semiconductor particles are also presented in the light of being advantageous over more established homogenous multi-component systems and supramolecular dyad complexes: the reported semi-heterogeneous system is straightforward to assemble and it works in a purely aqueous environment.

Selective Reduction of Aqueous Protons to Hydrogen with a Synthetic Cobaloxime Catalyst in the Presence of Atmospheric Oxygen
Fezile Lakadamyali, Masaru Kato, Nicoleta M. Muresan, Erwin Reisner
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 51, 37, 9381, 9384, WILEY-V C H VERLAG GMBH, 2012, [Peer-reviewed], [Lead author]
English, Scientific journal

Electronic structure calculation study of metal complexes with a phytosiderophore mugineic acid
Masaru Kato, Shinjiro Izuka, Takashi Fujihara, Akira Nagasawa, Sigenao Kawai, Tomokazu Tanaka, Toshiyuki Takayanagi
INORGANICA CHIMICA ACTA, 370, 1, 304, 310, ELSEVIER SCIENCE SA, May 2011, [Peer-reviewed], [Lead author]
English, Scientific journal, Structural and thermodynamic properties of biologically important metal-mugineic acid complexes have been studied from the theoretical side in order to understand the metal-chelating mechanism of phytosiderophore mugineic acid at an atomic level. Density-functional theory methods combined with the polarizable continuum model (PCM) have been employed to obtain free energies of complex formation and redox potentials for metal-mugineic acid complexes in solution. It has been found that the free energies of complex formation calculated at the B3LYP/PCM level of theory are in moderate agreement with available experimental results. The inclusion of explicit water molecules interacting with the carboxylic groups in deprotonated mugineic acid through strong hydrogen-bonds is found to further improve the calculated free energies of complex formation. (C) 2011 Elsevier B.V. All rights reserved.

Ferromagnetic Spin Ladder System: Stack of Chlorido-Bridged Dinuclear Copper(II) Complexes with 2-Methylisothiazol-3(2H)-one
Masaru Kato, Kazuo Hida, Takashi Fujihara, Akira Nagasawa
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, 4, 495, 502, WILEY-V C H VERLAG GMBH, Feb. 2011, [Peer-reviewed], [Lead author]
English, Scientific journal, A dinuclear copper(II) complex, [{Cu(II)Cl(O-mi)}(2)(mu-Cl)(2)] [mi = 2-methylisothiazol-3(2H)-one], has been synthesized and its molecular structure in the solid state determined by single-crystal X-ray analysis. The crystal consists of centrosymmetric dinuclear copper(II) units in which each copper(II) ion is doubly bridged by two chloride ions and has a slightly distorted square-planar geometry with a terminal chlorido ligand and a terminal mi ligand coordinated through the oxygen atom. The dinuclear units stack one on top of another to form a one-dimensional two-leg ladder structure. The magnetic susceptibility of the powder was measured in the temperature range 3.0-302 K. It was found that there are ferromagnetic interactions along the rung (in the same direction of the intramolecule; J(rung) = +5.03 +/- 0.03 cm(-1)) and the leg (in the same direction of the intermolecule; J(leg) = +1.96 +/- 0.02 cm(-1)) and an antiferromagnetic interaction along the diagonal (J(x) = -1.36 +/- 0.02 cm(-1)), the experimental data being fitted by the numerical calculation for a twelve-site ladder Hamiltonian. In addition, DFT calculations with the UB3LYP functional on the model complex [{Cu(II)Cl(O-mi)}(2)(mu-Cl)(2)] gave an intramolecular magnetic coupling constant J = +28.6 cm(-1) and indicated that the spin-density distribution on O in mi is less than that on the terminal Cl. We conclude that the O-donor ligand at the terminal position plays an essential role in the emerging intramolecular ferromagnetic interaction.

Molecular Structure and Electrochemical Behavior of Uranyl(VI) Complex with Pentadentate Schiff Base Ligand: Prevention of Uranyl(V) Cation-Cation Interaction by Fully Chelating Equatorial Coordination Sites
Koichiro Takao, Masaru Kato, Shinobu Takao, Akira Nagasawa, Gert Bernhard, Christoph Hennig, Yasuhisa Ikeda
INORGANIC CHEMISTRY, 49, 5, 2349, 2359, AMER CHEMICAL SOC, Mar. 2010, [Peer-reviewed]
English, Scientific journal, The U(VI) complex with a pentadentate Schiff base ligand (N,N'-disalicylidenediethylenetriaminate = saldien(2-)) was prepared as a starting material of a potentially stable U(V) complex without any possibility of U(V)O(2)(+)center dot center dot center dot U(V)O(2)(+) cation-cation interaction and was found in three different crystal phases. Two of them had the same composition of U(VI)O(2)(saldien)center dot DMSO in orthorhombic and monoclinic systems (DMSO = dimethyl sulfoxide, 1a and 1c, respectively). The DMSO molecule in both 1a and 1c does not show any coordination to U(VI)O(2)(saldien), but it is just present as a solvent in the crystal structures. The other isolated crystals consisted only of U(VI)O(2)(saldien) without incorporation of solvent molecules (1b, orthorhombic). A different conformation of the coordinated saldien(2-) in 1c from those in 1a and 1b was observed. The conformers exchange each other in a solution through a flipping motion of the phenyl rings. The pentagonal equatorial coordination of U(VI)O(2)(saldien) remains unchanged even in strongly Lewis-basic solvents, DMSO and N,N-dimethylformamide. Cyclic voltammetry of U(VI)O(2)(saldien) in DMSO showed a quasireversible redox reaction without any successive reactions. The electron stoichiometry determined by the UV-vis-NIR spectroelectrochemical technique is close to 1, indicating that the reduction product of U(VI)O(2)(saldien) is [U(V)O(2)(saldien)](-), which is stable in DMSO. The standard redox potential of [U(V)O(2)(saldien)](-)/U(VI)O(2)(saldien) in DMSO is -1.584 V vs Fc/Fc(+). This U(V) complex shows the characteristic absorption bands due to f-f transitions in its 5f(1) configuration and charge-transfer from the axial oxygen to U(5+).

Structural and electrochemical studies on uranyl(VI) complex with pentadentate Schiff base ligand: A guide to stable uranyl(V)
Koichiro Takao, Masaru Kato, Shinobu Takao, Akira Nagasawa, Andreas C. Scheinost, Gert Bernhard, Christoph Hennig, Yasuhisa Ikeda
ACTINIDES 2009, 9, 1, IOP PUBLISHING LTD, 2010, [Peer-reviewed]
English, International conference proceedings, A U(VI) complex with N,N'-disalicylidenediethylenetriaminate (saldien(2-)) was characterized by single crystal X-ray analysis and X-ray absorption fine structure (XAFS) spectroscopy, and its electrochemical behavior in a DMSO solution was studied. The obtained U(VI)-saldien(2-) complex recrystallized from DMSO was identified as orthorhombic (UO2)-O-VI(saldien)center dot DMSO. All coordination sites in the equatorial plane of UO22+ are occupied by coordinating O and N atoms of saldien(2-). Comparing a k(3)-weighted U L-III-edge EXAFS spectra of (UO2)-O-VI(saldien) in DMSO and DMF solutions with that in solid state, the molecular structure of (UO2)-O-VI(saldien) remains even in the solutions. Quasi-reversible redox waves of (UO2)-O-VI(saldien) were observed at E degrees = -1.582 +/- 0.005 V vs. Fc/Fc(+) (Delta E-p = 0.080-0.170 V at v = 0.010-0.500 V.s(-1)) in DMSO. UV-Vis-NIR absorption spectral change with the electrochemical reduction of (UO2)-O-VI(saldien) using the spectroelectrochemical technique shows isosbestic points clearly, indicating that the electrochemical reaction of (UO2)-O-VI(saldien) is only present. Using the absorbance change and the Nernstian equation, the electron stoichiometry in the reduction of (UO2)-O-VI(saldien) in DMSO was determined as 0.929. This quantity close to unity reveals a redox reaction, (UO2)-O-VI(saldien) + e(-) = [ (UO2)-O-V(saldien)](-), i. e., (UO2)-O-VI(saldien) without unidentate ligands results in the stable U(V) complex, [ (UO2)-O-V(saldien)](-), in DMSO. This U(V) species also shows the characteristic absorption bands of U(V) at 630, 700, 830, 1390, and 1890 nm as well as other U(V) complexes.

Linkage isomerism of pentaammine(dimethylsulfoxide)ruthenium(II/III) complexes: A theoretical study
Masaru Kato, Toshiyuki Takayanagi, Takashi Fujihara, Akira Nagasawa
INORGANICA CHIMICA ACTA, 362, 4, 1199, 1203, ELSEVIER SCIENCE SA, Mar. 2009, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Density functional theory (DFT) calculations have been performed for understanding the linkage isomerism of [Ru-II/III(NH3)(5)(dmso)](2+/3+) (dmso = dimethylsulfoxide) from a theoretical point of view. In particular, we focus on the interchange between O-bonded and S-bonded structures of the dmso ligand by oxidation/reduction. We have examined. five different exchange-correlation functionals (SVWN, BP86, mPWPW91, B3PW91, and B3LYP) in our DFT calculations and found that the relative stabilities of the O-bonded and S-bonded structures are largely dependent on the functional employed. From detailed analyses of atomic charge distributions, it has been found that the calculated atomic charges on the central metal ions are strongly correlated with the relative energies. We also studied the effect of solvation on the linkage isomerism using continuum solvation models. (C) 2008 Elsevier B. V. All rights reserved.

(-)(545)-fac-Delta-Tris(L-prolinato)cobalt(III) trihydrate
Masaru Kato, Miho Hayashi, Takashi Fujihara, Akira Nagasawa
ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, 64, M684, U621, BLACKWELL PUBLISHING, May 2008, [Peer-reviewed]
English, Scientific journal, The absolute configuration of the octahedral fac-CoN3O3 title complex, [Co(C5H8NO2)(3)]center dot 3H(2)O, has been determined by single-crystal X- ray analysis. A three-dimensional network of hydrogen bonds is observed between the proline carboxylate groups and the three uncoordinated water molecules.

Anion influence on the coordination polymer structures of silver(I) complexes with 2-methylisothiazol-3(2H)-one
Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
CRYSTENGCOMM, 10, 10, 1460, 1466, ROYAL SOC CHEMISTRY, 2008, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Silver(I) coordination polymers formed by self-assembly of ambidentate ligands, 2-methylisothiazol-3(2H)-one (MI) and 5-chloro-2-methylisothiazol-3(2H)-one (CMI), have been characterized by single crystal X-ray analysis. The structure of the cation in [Ag-I(mu-O-mi)(2)] X (X = ClO4- (1); SbF6- (2)) is a one-dimensional chain while that in the nitrate salt, [Ag-2(I)(mu-O-mi)](NO3)(2) (3), is a three-dimensional network. A silver(I) complex with CMI, [Ag-I(mu-O-cmi)(2)] ClO4 (4), has also been synthesized and the cation has a one-dimensional chain structure. Although both MI and CMI have both O-and S-donor moieties, the oxygen atom dominantly coordinates to the silver(I) centre. The anion influence on the chain structure is attributed to the competition for the coordination ability between anions and MI, and the flexibility of the coordination sphere of d(10) silver(I) ion.

5-Chloro-2-methylisothiazolin-3-one: intermolecular two-dimensional networks via unusual C-Cl...O=C interactions
Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS, 63, O3097, U2523, INT UNION CRYSTALLOGRAPHY, Jul. 2007, [Peer-reviewed], [Lead author]
English, Scientific journal, The title molecule, C4H4ClNOS, contains an essentially planar five-membered ring. The C - C(= O) bond is slightly longer than expected. In the crystal structure, two-dimensional networks are formed through intermolecular C - Cl...O = C interactions [Cl...O = 2.9811 (19) angstrom].

3-hydroxy-2-methylisothiazolium chloride monohydrate: an intermolecular three-dimensional network via O-H center dot center dot center dot O and O-H center dot center dot center dot Cl hydrogen bonds
Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, 63, O1839, O1841, BLACKWELL PUBLISHING, Apr. 2007, [Peer-reviewed], [Lead author]
English, Scientific journal, The title compound, C4H6ClNOS center dot H2O, has a planar five-membered ring, with a delocalized positive charge. A three-dimensional network is formed through intermolecular O-H center dot center dot center dot O and O-H center dot center dot center dot Cl hydrogen bonds between 3-hydroxy-2-methylisothiazolium cations and water molecules, and between water molecules and chloride anions.

Tetra-n-propylammonium perchlorate
T Fujihara, M Kato, A Nagasawa
ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE, 61, O1439, O1440, BLACKWELL MUNKSGAARD, May 2005, [Peer-reviewed]
English, Scientific journal, The crystallographic analysis of the title compound, C12H28N+• ClO4-, (I), shows that intermolecular C-H••• O interactions stabilize the crystal structure. The compound is isomorphous with tetra-n-propylammonium iodide, whose structure has been described by Yoshida et al. [ Acta Cryst. ( 1994). C50, 1758-1760].

Electrocatalysis Driven by Pt Alloy Nanoframes and Nanowires.
加藤優, 八木一三, 触媒, 66, 1, 2024

Progress and Future Challenges in Non-Platinum Electrocatalysts for the Oxygen Reduction Reaction
加藤優, 八木一三, 太陽エネルギー, 49, 274, 36, 41, 2023, [Lead author]
Japanese

Morphological change and oxygen reduction reaction activity of Pt-Ni nanowire catalysts under potential load environment
加藤優太, 井口誼美, ZHUANG Yu, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 88th, 2021

Dehydrogenation of Primary Amines at Multi-layered Photo-anodes
姉帯一樹, 永井かなえ, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 88th, 2021

Nitrate Reduction at Tin-modified Noble Metal Single Crystalline Electrodes
鵜沼佑規, 奥井学, 田口哲, 加藤優, 加藤優, 八木一三, 八木一三, 表面と真空, 64, 8, 2021

FTO上にスパッタリングしたNiによるベンジルアミンの電気化学的酸化
姉帶一樹, 永井かなえ, 加藤優, 八木一三, 日本表面真空学会東北・北海道支部学術講演会講演予稿集, 2019, 2020

Effects of catalytic supports on electrocatalytic activity of Pt-Ni nanostructures
中干場亮太, LI Tianchi, YU Zhuang, 井口誼美, 阿部大輝, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 87th, 2020

Effect of molecular grafting onto Pt/C catalyst surface on electrocatalytic activity
村松舜, ZHUANG Yu, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 87th, 2020

Oxygen Reduction Activity and Structural Conversion of Pt-Alloy Nanowires
加藤優, LI Tianchi, 井口誼美, ZHUANG Yu, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 87th, 2020

Chirality dependence of electron transfer rate on homocysteine-modified electrode
岡紗雪, 加藤優, 加藤優, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2020, 2020

Nitrate reduction reaction at well-defined surfaces of tin-modified platinum-palladium single crystalline electrodes
鵜沼佑規, 奥井学, 田口哲, 星永宏, 加藤優, 加藤優, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2020, 2020

In situ observation of metalloenzymes adsorption process and construction of lipid bilayer on SAM-Au electrode
吉田生未, 鳴海旭, 増田侑也, 當舎武彦, 加藤優, 加藤優, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2020, 2020

Oxygen reduction catalytic activity of metal-nanoparticle-free (Cu,Fe)-N doped carbon catalysts
阿部大輝, 藤林那月, 加藤優, 保田諭, 八木一三, 電池討論会PDF要旨集(CD-ROM), 61st, 2020

Synthesis and electrocatalytic activity for oxygen reduction reaction of Pt-Ni nanowires
井口誼美, LI Tianchi, 加藤優, 八木一三, 電池討論会PDF要旨集(CD-ROM), 61st, 2020

SAM修飾Au電極における金属酵素の吸着と脂質膜構築のその場観察
吉田生未, 鳴海旭, 増田侑也, 當舎武彦, 加藤優, 八木一三, 日本表面真空学会東北・北海道支部学術講演会講演予稿集, 2019, 2020

Electrochemical grafting on graphene/metal achieved by different schemes
西山佳祐, 鶴飼里菜, 丹野駿, 加藤優, 田村和久, 保田諭, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 87th, 2020

Analysis of ultrathinNafion film/Pt(111) interfacial structure
金内理矩, 齋藤僚, 加藤優, 田村和久, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 87th, 2020

白金合金ナノワイヤーの酸素還元活性と電子状態
加藤優, 井口誼美, 李天馳, 庄宇, 八木一三, 触媒討論会討論会A予稿集(CD-ROM), 126th, 2020

単層グラフェンのプロトン透過能と電気化学的手法を利用したグラフェン-金属界面への水素ナノバブル形成
保田諭, 田村和久, 矢野雅大, 寺澤知潮, 加藤優, 八木一三, 朝岡秀人, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 66th, 2019

Pt-Ni合金ナノフレーム電極触媒の酸素還元活性および耐久性に対する担体効果
加藤優, 小倉和也, 徳田翔一, LI Tianch, 中干場亮太, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

白金ナノワイヤーの調製と酸素還元触媒活性
LI Tianchi, 小倉和也, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

酸性水溶液中での酸素還元活性に対する鉄-銅共ドープ効果
藤林那月, 加藤優, 加藤優, 保田諭, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

膜電極接合体カソードにおける電極表面酸素種の軟X線分光計測
石原知子, 石原知子, 加藤優, 加藤優, 新部正人, 徳島高, 堀川裕加, 堀川裕加, 永山まゆみ, 林灯, 植野一輝, 植野一輝, 橋本由介, 大浦正樹, 大浦正樹, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

グラフェン被覆した種々の金属基板への電気化学的分子修飾
鶴飼里菜, 丹野駿, 保田諭, 田村和久, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

自己組織化単分子層を介して電極上に固定した一酸化窒素還元酵素の分光電気化学
鳴海旭, 増田侑也, 中川省吾, 當舎武彦, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 99th, 2019

グラフェン-金属界面で形成されるナノバブルの水素同位体効果
保田諭, 田村和久, 矢野雅大, 寺澤知潮, 加藤優, 八木一三, 朝岡秀人, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

Pt-Niナノ構造体の電極触媒活性に対する担体効果
中干場亮太, LI Tianchi, 小倉和也, 藤林那月, 保田諭, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 99th, 2019

触媒担体表面への分子修飾によるアイオノマー配向制御と酸素還元活性への影響
村松舜, 加藤優, 長谷川直樹, 長谷川直樹, 北野直紀, 加藤久雄, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 99th, 2019

グラフェン被覆Au(111)表面へのアニリン誘導体の修飾
西山佳祐, 鶴飼里菜, 丹野駿, 加藤優, 保田諭, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 99th, 2019

単層グラフェンへの構造規定欠陥の導入と電気化学水素ポンプ法によるプロトン透過能評価
保田諭, 寺澤知潮, 矢野雅大, 小河浩晃, 加藤優, 八木一三, 朝岡秀人, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 80th, 2019

金属電極表面におけるアイオノマーモデル電解質の挙動解析
八木一三, 加藤優, 野津英男, 田村和久, SPring-8/SACLA利用研究成果集(Web), 7, 2, 2019

窒素ドープカーボン担体による白金合金ナノワイヤの酸素還元活性と耐久性への影響
庄宇, 中干場亮太, 李天馳, 加藤優, 八木一三, 触媒討論会討論会A予稿集(CD-ROM), 124th, 2019

Pt-Ni合金ナノ構造体の酸素還元活性に対する担体効果
加藤優, 小倉和也, 徳田翔一, 中干場亮太, 李天馳, 庄宇, 八木一三, 触媒討論会討論会A予稿集(CD-ROM), 124th, 2019

Correlation between film thickness and oxygen reduction reaction activity at ionomer film coated on Pt single crystal electrode
金内理矩, 齋藤僚, 加藤優, 加藤優, 田村和久, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2019, 2019

Permeability Evaluation of Hydrogen Ion Isotope of Graphene
保田諭, 寺澤知潮, 矢野雅大, 加藤優, 八木一三, 朝岡秀人, 日本表面真空学会学術講演会要旨集(Web), 2019, 2019

Transfer of chemically modified graphene onto other metal substrates
西山佳祐, 鶴飼里菜, 丹野駿, 加藤優, 加藤優, 田村和久, 保田諭, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2019, 2019

膜電極接合体を用いたグラフェンのプロトン透過能評価
保田諭, 寺澤知潮, 矢野雅大, 加藤優, 八木一三, 朝岡秀人, 電気化学秋季大会講演要旨集(CD-ROM), 2019, 2019

白金合金ナノワイヤー触媒における酸素還元反応活性の向上
LI Tianchi, 小倉和也, 加藤優, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2019, 2019

酸素還元活性を示す白金合金ナノ構造体への担体効果
加藤優, 中干場亮太, 小倉和也, LI Tianchi, ZHUANG Yu, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2019, 2019

多層被覆CdSナノロッドによる水の光電気化学的酸化
永井かなえ, 石原由貴, 加藤優, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2019, 2019

脂質膜修飾電極における金属酵素反応の追跡
増田侑也, 加藤優, 加藤優, 當舎武彦, 中川省吾, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 86th, 2019

Tracking the formation process of an artificial bilayer lipid membrane at metalloenzyme-electrode interfaces
加藤優, 加藤優, 鳴海旭, 増田侑也, 中川省吾, 當舎武彦, 八木一三, 八木一三, 日本表面真空学会学術講演会要旨集(Web), 2019, 2019

APD法により調製したカーボン担持Pt-Niナノ粒子の酸素還元活性
原由樹, 加藤優, 八木一三, 化学系学協会北海道支部冬季研究発表会(Web), 2018, 2018

表面被覆した金属硫化物電極の調製と光電気化学特性
石原由貴, 加藤優, 八木一三, 化学系学協会北海道支部冬季研究発表会(Web), 2018, 2018

表面被覆した金属硫化物電極の調製と光電気化学性質
石原由貴, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

窒素導入カーボン担持Pt-Ni合金ナノフレームの酸素還元活性および耐久性
小倉和也, 中川省吾, 徳田翔一, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

アークプラズマ蒸着Pt-Niナノ粒子の酸素還元活性と担体効果
原由樹, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

種々の基板金属を用いたグラフェンへの電気化学的分子修飾
鶴飼里菜, 丹野駿, 保田諭, 田村和久, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

グラフェン-金属界面で形成した水素ナノバブル評価
保田諭, 田村和久, 佐藤祐輔, 加藤優, 丹野駿, 八木一三, 朝岡秀人, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

アイオノマー極薄膜を被覆したPt(111)電極の酸素還元反応
齋藤僚, 二本柳聡史, 田村和久, 田原太平, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

電気化学的に制御された一酸化窒素還元酵素の表面増強赤外吸収分光計測
中川省吾, 加藤優, 當舎武彦, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

グラフェンへの電気化学的分子修飾における基板金属の影響
鶴飼里菜, 丹野駿, 佐藤祐輔, 加藤優, 八木一三, 化学系学協会北海道支部冬季研究発表会(Web), 2018, 2018

分子プローブを用いた一酸化窒素還元酵素修飾電極の表面増強赤外吸収分光計測
中川省吾, 加藤優, 當舎武彦, 八木一三, 化学系学協会北海道支部冬季研究発表会(Web), 2018, 2018

コバルト含有カーボン電極触媒が示す二元機能触媒活性
米内翼, 菅野康仁, 加藤優, 加藤優, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

多核金属錯体担持カーボン酸素還元電極触媒のX線吸収分光法によるその場観察
松原直啓, 武藤毬佳, 加藤優, 加藤優, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 85th, 2018

軟X線分光測定による白金表面への酸素種の吸着脱離の観察
石原知子, 石原知子, 堀川裕加, 堀川裕加, 加藤優, 加藤優, 徳島高, 大浦正樹, 大浦正樹, 八木一三, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2018, 2018

単層グラフェンへの電気化学ドーピングとその電気化学的挙動の評価
保田諭, 田村和久, 佐藤祐輔, 加藤優, 丹野駿, 朝岡秀人, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2018, 2018

多核銅錯体埋込型カーボン電極触媒の酸素還元活性と活性中心構造の解明
加藤優, 加藤優, 松原直啓, 武藤鞠佳, 上村洋平, 脇坂祐輝, 松村大樹, 高草木達, 朝倉清高, 八木一三, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

Au(111)電極上に合成した単層グラフェンのプロトン透過能評価
保田諭, 中島浩司, 森本崇宏, 中島秀朗, 岡崎俊也, 田村和久, 加藤優, 丹野駿, 八木一三, 村越敬, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 64th, 2017

単層グラフェンの電気化学的プロトン透過能評価
保田諭, 中島浩司, 森本崇宏, 中島秀朗, 岡崎俊也, 田村和久, 加藤優, 丹野駿, 八木一三, 村越敬, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

Snで修飾した金属単結晶電極を用いた硝酸イオン還元
奥井学, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

Pt(111)電極におけるアイオノマー膜厚の影響評価
齋藤僚, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

カーボン担持PtNi合金ナノ構造体の酸素還元活性
小倉和也, 徳田翔一, 加藤優, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

アークプラズマ蒸着を用いて調製した金属ナノ粒子電極による硝酸イオン還元
荒木愛, 加藤優, 田口哲, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 84th, 2017

Au(111)上に成膜した単層グラフェンへの電気化学的分子修飾
丹野駿, 佐藤祐輔, 中島浩司, 田村和久, 保田諭, 村越敬, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

アイオノマーを複合した撥水性白金担持カーボン電極の酸素還元活性
矢野祥平, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

Au(111)上に成膜した単層グラフェンへの電気化学的分子修飾
丹野駿, 佐藤祐輔, 中島浩司, 田村和久, 保田諭, 村越敬, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

アークプラズマ蒸着法により調製したPt-Ni電極触媒の酸素還元活性
原由樹, 荒木愛, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

Pt-Ni合金ナノ構造体電極触媒の合成とそのORR活性評価
徳田翔一, 小倉和也, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

アイオノマー複合金属担持カーボン電極の撥水性及び酸素還元活性
矢野祥平, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

Pt-Ni合金ナノ構造体電極触媒の合成とそのORR活性評価
徳田翔一, 小倉和也, 加藤優, 八木一三, 日本化学会春季年会講演予稿集(CD-ROM), 97th, 2017

グラフェン-Au(111)界面に形成した水素ナノバブルのSTM観察
保田諭, 田村和久, 佐藤祐輔, 加藤優, 丹野駿, 八木一三, 朝岡秀人, 電気化学秋季大会講演要旨集(CD-ROM), 2017, 2017

Pt(111)電極上におけるアイオノマー膜厚の酸素還元反応に対する影響
齋藤僚, 二本柳聡史, 田村和久, 田原太平, 加藤優, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2017, 2017

表面増強赤外吸収分光法による電極表面上一酸化窒素還元酵素の反応追跡
加藤優, 中川省吾, 當舎武彦, 中田耕, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2017, 2017

コバルト含有カーボン電極触媒の調製とその酸素還元活性の評価
米内翼, 加藤優, 加藤優, 八木一三, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2017, 2017

多核金属錯体埋込型カーボン電極触媒におけるin situ XAFS測定
松原直啓, 武藤毬佳, 加藤優, 加藤優, 八木一三, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2017, 2017

表面増強赤外吸収分光による一酸化窒素還元酵素の電気化学反応追跡
中川省吾, 加藤優, 當舎武彦, 八木一三, 錯体化学会討論会講演要旨集, 67th, 2017

ナノレベルでの単層グラフェンのプロトン透過能評価
保田諭, 田村和久, 丹野駿, 佐藤祐輔, 加藤優, 八木一三, 朝岡秀人, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 78th, 2017

表面増強赤外分光法による一酸化窒素還元酵素修飾電極の反応計測
八木一三, 中川省吾, 當舎武彦, 加藤優, 分子科学討論会講演プログラム&要旨(Web), 11th, 2017

光化学系II複合体で表面修飾された層状複水酸化物電極による水の光酸化
加藤優, 佐藤久子, 杉浦美羽, 八木一三, 電気化学会大会講演要旨集(CD-ROM), 83rd, ROMBUNNO.3J23, 23 Mar. 2016
Japanese

Reduction of nitrate on tin-modified single-crystal electrodes
Okui Manabu, Kato Masaru, Yagi Ichizo, Abstract of annual meeting of the Surface Science of Japan, 36, 68, 68, 2016
近年、硝酸イオンによる地下水汚染が問題となっており、硝酸イオン除去法の開発発展が求められている。電極触媒を用いた先行研究ではSnを修飾したPtやPdが高い触媒活性を示すことが報告されてきたが、その多くは多結晶電極を用いているため表面原子配列が活性に与える影響については明確にされていない。本研究ではPtやPd、Pd-Pt合金の単結晶電極を用いて、表面原子配列がその活性に与える影響について検討する。 , The Surface Science Society of Japan, Japanese

多核銅錯体をカーボンに組み込んだ非白金系電極触媒
加藤優, 武藤毬佳, 八木一三, 電気化学秋季大会講演要旨集(CD-ROM), 2015, 2015

層状複水酸化物修飾電極を用いた光化学系IIの光電気化学
KATO MASARU, SATO HISAKO, SUGIURA MIWA, 電気化学秋季大会講演要旨集, 2014, 200, 27 Sep. 2014
Japanese

Bio-inorganic hybrid water oxidation electrodes of Photosystem II and layered double hydroxide
KATO Masaru, SATO Hisako, SUGIURA Miwa, SUGIURA Miwa, 生物物理, 54, Supplement 1-2 (Web), 2P251 (WEB ONLY), 20 Aug. 2014
The Biophysical Society of Japan General Incorporated Association, English

自然界唯一の水の酸化触媒である光化学系IIの酵素電気光化学
加藤優, 佐藤久子, 杉浦美羽, 光化学討論会要旨集(CD-ROM), 2014, ROMBUNNO.1B20, 2014
Japanese

Encyclopedia of Solid-Liquid Interfaces　　　　　　　　　　　　　　　
Bio-inspired Cu,Fe-codoped carbon electrocatalysts for oxygen reduction reaction
Elsevier, 2024, 9780323856706, [Contributor]

ヘムタンパク質の科学 : 生理機能の理解とその展開に向けて
城, 宜嗣, 青野, 重利, 齋藤, 正男, 第5章 測定解析技術 第6節 ヘムタンパク質の電気化学
エヌ・ティー・エス, May 2022, 9784860437787, 2, 8, 413, 8p, 図版34p, Japanese, [Contributor]

Development of Noble Metal-Free Electrocatalysts Inspired by Metalloenzymes　　　　　　　　　　　　　　　
Masaru Kato
The 29th International SPACC Symposium, 05 Sep. 2024, English, Invited oral presentation
[Invited]

Protein film electrochemistry and vibrational spectroscopy of metalloenzymes　　　　　　　　　　　　　　　
Masaru Kato
Japan-Korea-Taiwan Bioinorganic Chemistry Symposium 2024, 17 Jul. 2024, English, Invited oral presentation
[Invited]

タンパク質フィルム電気化学から人工電極触媒開発への展開　　　　　　　　　　　　　　　
加藤優
第132回触媒討論会, 13 Sep. 2023, Japanese, Invited oral presentation
[Invited]

電極触媒におけるその場X線吸収分光計測　　　　　　　　　　　　　　　
加藤優
第1回先端放射光活用研究会「放射光を用いた触媒キャラクタリゼーションの現在と未来」, 22 Jul. 2023, Japanese, Invited oral presentation
[Invited]

金属酵素に学ぶ電極触媒の設計と開発　　　　　　　　　　　　　　　
加藤優
FCDIC第30回燃料電池シンポジウム, 25 May 2023, Japanese, Invited oral presentation
[Invited]

Development of Pt alloy and Pt-free electrocatalysts for polymer electrolyte fuel cells　　　　　　　　　　　　　　　
International Conference on Sustainable Energy Materials, 2023 Sapporo, 10 Apr. 2023, English, Invited oral presentation
[Invited]

金属酵素に学ぶ電極触媒開発　　　　　　　　　　　　　　　
加藤優
第5回日本表面・真空学会若手部会研究会, 10 Nov. 2022, Japanese, Invited oral presentation
[Invited]

膜貫通型金属酵素の電気化学と振動分光計測　　　　　　　　　　　　　　　
2022年電気化学秋大会, 09 Sep. 2022, Japanese, Invited oral presentation
[Invited]

金属酵素に学ぶ電極触媒の設計と開発　　　　　　　　　　　　　　　
第29回FCDIC燃料電池シンポジウム, 27 May 2022, Japanese, Invited oral presentation
[Invited]

Pt–Ni合金ナノ構造体の酸素還元活性に対する担体効果　　　　　　　　　　　　　　　
加藤優
第124回触媒討論会, 18 Sep. 2019, Japanese, Invited oral presentation
[Invited]

Electrochemical Oxygen Reduction Catalyzed at Pt–Ni Nanostructured Electrocatalysts Immobilized on Nitrogen-Doped Carbon Supports　　　　　　　　　　　　　　　
Masaru Kato
The 235th Meeting of the Electrochemical Society, 28 May 2019, Japanese, Invited oral presentation
[Invited]

Oxygen Reduction Electrocatalysts Inspired by Multinuclear Metal Complex Active Sites of Metalloenzymes　　　　　　　　　　　　　　　
Masaru Kato
Bangladesh Chemical Congress 2018 (BCC 2018), 17 Oct. 2018, English, Invited oral presentation
[Invited]

Incorporation of Multinuclear Copper Active Sites into Nitrogen-Doped Graphene for Electrochemical Oxygen Reduction　　　　　　　　　　　　　　　
3rd International Symposium of Quantum Beam Science at Ibaraki University, 31 May 2018, English, Invited oral presentation
[Invited]

Bio-inspired Multinuclear Catalytic Active Sites Incorporated in Nitrogen-Doped Carbon for Oxygen Reduction Reaction　　　　　　　　　　　　　　　
Masaru Kato
International Symposium on Pure & Applied Chemistry (ISPAC) 2017, 10 Jun. 2017, English, Invited oral presentation
[Invited]

金属酵素に学ぶ電極触媒開発　　　　　　　　　　　　　　　
加藤優
錯体化学若手の会北海道支部勉強会, 27 Nov. 2015, Japanese, Invited oral presentation
[Invited]

Multinuclear copper-based electrocatalysts for oxygen reduction reaction　　　　　　　　　　　　　　　
Masaru Kato
Graduate Seminar, Department of Chemical Engineering, National Cheng Kung University, 02 Oct. 2015, English, Invited oral presentation

水の酸化反応を触媒する光合成タンパク質、光化学系II複合体の光電気化学　　　　　　　　　　　　　　　
第21回若手研究者交流会, 28 Jun. 2015, Japanese, Invited oral presentation
[Invited]

Deprotonation of a multi-nuclear copper complex for high oxygen reduction reaction activity investigated by in situ X-ray absorption fine structure spectroscopy　　　　　　　　　　　　　　　
Masaru Kato
227th Meeting of the Electrochemical Society, 27 May 2015, English, Invited oral presentation
[Invited]

Protein film photoelectrochemistry of Photosystem II　　　　　　　　　　　　　　　
8th International Symposium on Nanomedicine (ISNM2014), 04 Dec. 2014, English, Invited oral presentation
[Invited]

可視光照射下での水の光分解を目指した光合成酵素電極による酸素発生とコバルト金属錯体触媒による水素発生　　　　　　　　　　　　　　　
加藤優
2013年日本化学会中国四国支部大会, 16 Nov. 2013, English, Invited oral presentation
[Invited]

電極支持生体膜反応場を用いたタンパク質間相互作用の理解とカスケード反応への展開
科学研究費助成事業 基盤研究(C)
01 Apr. 2021 - 31 Mar. 2024
加藤 優
膜タンパク質は細胞膜を構成する脂質分子や他の可溶性タンパク質等と相互作用や電子移動することで，細胞膜を介したシグナル伝達やエネルギー生産といったタンパク質機能を発現することが知られている．膜タンパク質-脂質間やタンパク質-タンパク質間相互作用といった比較的弱い相互作用を膜タンパク質が機能している状態で直接観察することができれば，生体内反応の理解，医薬品やバイオセンサー開発等の促進が期待できる．
本研究では，膜タンパク質-脂質間やタンパク質-タンパク質間相互作用と酵素活性相関の理解を可能とする，人工生体膜固定化電極の構築を目指す．特に膜タンパク質の中でも生体内電子移動や酵素反応において重要であるヘムを含む膜貫通型金属酵素に着目する．2021年度では，ミトコンドリア内部で酸素を水へ還元する金属酵素であるチトクロムc酸化酵素の固定化電極を作製し，タンパク質の電極表面配向やリン脂質の種類の違いによる膜タンパク質-脂質間やタンパク質-タンパク質間相互作用，酵素活性への影響を調べた．酵素活性は電気化学測定により，人工脂質二分子膜形成やタンパク質間相互作用は表面敏感な分光手法である表面増強赤外吸収(SEIRA)分光測定により調べた．
日本学術振興会, 基盤研究(C), 北海道大学, 21K05124

電解をコアテクノロジーとした集積化可能なパーソナルグリッド(PG)の実現に関する調査研究　　　　　　　　　　　　　　　
ムーンショット型研究開発事業 新たな目標検討のためのビジョン策定（ミレニア・プログラム）
Jan. 2021 - Jun. 2021
長澤 兼作, 才田隆広, 加藤優, 滝本大裕, 八木裕之, 山口清
国立研究開発法人科学技術振興機構

Surface-sensitve spectro-electrochemistry on metalloenzyme electrodes
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
Apr. 2016 - Mar. 2019
KATO MASARU
In this work, we prepared gold electrodes that are active to surface-enhanced infrared absorption (SEIRA) spectroscopy and immobilized a nitric oxide reductase (NOR), which is a trans-membrane metalloenzyme and selectively catalyzes the reduction of nitric oxide (NO) to nitrous oxide (N2O). The NOR electrode showed the electro-catalytic NO reduction activity, indicating that the enzyme was active even on the gold electrode. We also performed SEIRA spectroscopy of the NOR electrode under potential control using carbon monoxide as a vibrational probe. Potential-dependent SEIRA spectra allowed us to determine the redox potentials of the heme and non-heme iron cofactors, which serve as the active site, and then gained the mechanistic insights into the enzymatic NO reduction.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 16K20882

酸化還元誘起結合異性錯体の設計、合成、および分子間光電子移動反応
科学研究費助成事業 特別研究員奨励費
2009 - 2010
加藤 優
ベンゾトリアゾール(Hbt)は配位可能な窒素原子を二つ有する両座配位子である.過去に酸化還元誘起結合異性を示すルテニウム錯体が合成されていて,Ru^の状態ではHbtが2位の窒素(N(2))で中心金属イオンに配位しているが,中心金属イオンを酸化してRu^の状態にするとHbtが3位の窒素(N(3))で配位することが知られている.そこで,Hbtを両座配位子とし,補助配位子として光受容性配位子である2,2':6',2''-terpyridine (tpy)や2,2'-bipyridine誘導体を有するルテニウム錯体[Ru^(Hbt) L (tpy)](CF_3SO_3)_2(Lは4,4'位をH,Me,OMe,tBu,Phで置換された2,2'-bipyridine誘導体)を合成し,溶液内酸化還元挙動をサイクリックボルタンメトリー測定により検討を行った.しかしながら酸化還元誘起結合異性に由来するようなピークを観測することはできず酸化還元誘起結合異性挙動が見られなかった.そこで,代替化合物として過去に我々が報告している酸化還元誘起結合異性を示す錯体[Ru(NH_3)_5(mi-S)]^(mi=2-methylisothiazol-3(2H)-One ; n=3 or 2),光増感剤ルテニウム錯体[Ru^(bpy)_3]Cl_2,そしてmethylviologen (MV)を用い,三元系分子間光電子移動反応による酸化還元結合異性を誘起するシステムの構築を目指した.その過程でRu^の状態miが硫黄で,Ru^では酸素で配位した錯体をそれぞれ合成単離し,単結晶X線構造解析によって構造を決定した。このように酸化還元結合異性体の単離例は極めて少なく,これは予期せぬ大きな成果であった.
日本学術振興会, 特別研究員奨励費, 埼玉大学, 09J07915