NAGAI Takaaki


Institute of Advanced Sciences

Job Title

Specially Appointed Assistant Professor

Education 【 display / non-display

  • 1994.4

    Yokohama National University   Doctor Course   Completed

  • 1992.4

    Yokohama National University   Master Course   Completed

  • 1988.4

    Yokohama National University   Graduated

Degree 【 display / non-display

  • Doctor of Engineering - Yokohama National University

  • Master of Engineering - Yokohama National University

Campus Career 【 display / non-display

  • 2020.3

    Duty   Yokohama National UniversityInstitute of Advanced Sciences   Specially Appointed Assistant Professor  


Papers 【 display / non-display

  • Effects of Foreign Elements Added Oxide-Based Electrocatalyst for Oxygen Reduction Reaction as Non-Precious Metel Cathodes

    K. Matsuzawa, M. Obata, Y. Takeuchi, Y. Ohgi, K. Ikegami, T. Nagai, R. Monden and A. Ishihara

    ECS Transactions   108 ( 7 )   181 - 188   2022.6  [Reviewed]

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    Language:English   Publishing type:Research paper (international conference proceedings)   Single Work  

  • Degradation Analysis of Pt/Nb–Ti4O7 as PEFC Cathode Catalysts with Controlled Arc Plasma–deposited Platinum Content

    MA Yongbing, KAJIMA Hirokata, SHIMASAKI Yuta, NAGAI Takaaki, NAPPORN Teko W., WADA Hiroaki, KURODA … Show more authors

    電気化学および工業物理化学   advpub ( 0 )   057004 - 057004   2022.5

    DOI Web of Science CiNii Research

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:公益社団法人 電気化学会   Joint Work  

    For polymer electrolyte fuel cell cathodes, highly durable supports are required to prevent catalyst degradation in supports. In this study, as model Pt catalysts, 2–10 wt% Pt was deposited on Magnéli-phase niobium-doped macroporous Ti<sub>4</sub>O<sub>7</sub> (Nb–Ti<sub>4</sub>O<sub>7</sub>) mounted on glassy carbon rods using the coaxial arc plasma deposition method. The morphologies of 2, 5, and 10 wt% Pt catalysts showed the hemisphere fine particles, islands with ca. 1.4 nm diameter and ca. 2.4 nm thickness, and films with ca. 3.3 nm thickness, respectively. During start/stop accelerated durability tests (ADTs) of 5000 cycles following the Fuel Cell Commercialization Conference of Japan protocol, Pt was slightly agglomerated; consequently, the morphologies of the 2, 5, and 10 wt% Pt catalysts were island-like with 3.5 nm thickness, chain bead-like with 4 nm thickness, and film-like with 4 nm thickness, respectively. This slight agglomeration led to good durability during the ADTs. Herein, the oxygen reduction reaction (ORR) mass activity (MA) values at 0.9 V vs. reversible hydrogen electrode (RHE) of the 2, 5, and 10 wt% Pt catalysts were 79, 60, and 36 A g<sub>Pt</sub><sup>-1</sup> after 5000 cycles ADT, respectively, which had declining ratios after 5000 cycles were 32 %, 17 %, and 0 %, respectively. The island-like and film-like Pt/Nb–Ti<sub>4</sub>O<sub>7</sub> presented activity and durability comparable to a Pt/C catalyst, which was 42 A g<sub>Pt</sub><sup>-1</sup> (0.9 V vs. RHE) with a 12 % of declining ratio after the ADTs. The durability of the MA suggested that the different affinity caused by different crystal faces led to the slight agglomeration of 2, 5, and 10 wt%_Pt/Nb–Ti<sub>4</sub>O<sub>7</sub> catalysts. These catalysts showed electrochemical surface areas (ECSAs) of 36, 27, and 29 m<sup>2</sup> g<sup>−1</sup> after the ADTs, with declining ratios as low as 20 %, 6 %, and 0 %, respectively. All Pt/Nb–Ti<sub>4</sub>O<sub>7</sub> catalysts showed higher durability of the ECSAs than the Pt/C catalyst, which was 68 m<sup>2</sup> g<sup>−1</sup> with a 30 % declining ratio after the ADT. Different from common Pt nanoparticle catalysts, which agglomerate into large spherical Pt particles, the slight agglomeration was caused by the interconnection of the deposits and supplemented by a limited increase in the diameter or thickness. The island-like morphology of Pt with a limited thickness presented both high durability and activity among the Pt/Oxide catalysts.

  • Applicability of P-doped SnO2 as an Oxide Support for PEFC Cathodes

    21 ( 3 )   79 - 88   2022.2  [Reviewed]

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Single Work  

  • Noble Metal-Added Titanate Nanosheets for PEFC Cathode

    Y. Takeuchi, K. Matsuzawa, T. Nagai, K. Ikegami, Y. Kuroda, R. Monden, and A. Ishihara

    ECS Transactions   104 ( 8 )   337 - 344   2021.10  [Reviewed]

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    Language:English   Publishing type:Research paper (international conference proceedings)   Single Work  

  • Factors Affecting ORR Activity of Nb-added TiOx Catalysts Supported on CNTs for PEFC

    21 ( 1 )   80 - 86   2021.7  [Reviewed]

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Single Work  

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Review Papers 【 display / non-display

  • 啓蒙普及の事例ー東京タワー・キッズ環境科学博士

    永井崇昭, 和田徹也

    燃料電池   17 ( 3 )   42 - 45   2018.1

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    Language:Japanese   Publishing type:Meeting report   Publisher:燃料電池開発情報センター   Joint Work  

  • 横浜国立大学グリーン水素研究センターの活動紹介と社会貢献

    太田健一郎, 石原顕光, 永井崇昭

    JETI   66 ( 1 )   121 - 125   2018.1

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    Language:Japanese   Publishing type:Rapid communication, short report, research note, etc. (bulletin of university, research institution)   Publisher:株式会社日本出版制作センター   Joint Work