顔写真

トドロキ　ナオト
轟　直人
Naoto Todoroki
所属
大学院環境科学研究科　先端環境創成学専攻　環境創成計画学講座（環境材料表面科学分野）
職名
准教授
学位

  • 博士（工学）（東北大学）

  • 修士（工学）（東北大学）

プロフィール

2014年3月：東北大学大学院工学研究科博士課程後期3年修了。2014年3月 博士(工学）（東北大学)。2014年4月：東北大学大学院環境科学研究科 助教。2020年1月：同 准教授（現職）。水電解、CO2電解、燃料電池など、カーボン・ニュートラル実現に資するエネルギー・物質変換触媒材料に関する研究に従事。

経歴 5

  • 2020年1月 ～ 継続中
    東北大学　大学院環境科学研究科　准教授

  • 2023年4月 ～ 2024年3月
    九州大学　先導物質化学研究所　研究指導者（兼任）

  • 2020年11月 ～ 2022年3月
    JSTさきがけ「反応制御」領域 研究員（兼任）

  • 2014年4月 ～ 2019年12月
    東北大学　大学院環境科学研究科　助教

  • 2010年4月 ～ 2011年5月
    昭栄化学工業株式会社

学歴 3

  • 東北大学　大学院工学研究科　知能デバイス材料学専攻 博士後期課程

    2011年10月 ～ 2014年3月

  • 東北大学　大学院工学研究科　知能デバイス材料学専攻 博士前期課程

    2008年4月 ～ 2010年3月

  • 東北大学　工学部　材料科学総合学科

    2004年4月 ～ 2008年3月

委員歴 11

  • 水素エネルギー協会　大会実行委員会

    2024年4月 ～ 継続中

  • 東北大材料科学材料科学高等研究所 水素科学GXオープンイノベーションセンター　学内アソシエイトメンバー

    2022年10月 ～ 継続中

  • 日本金属学会　講演大会委員

    2021年4月 ～ 継続中

  • 燃料電池開発情報センター　50年後FCWG 委員

    2019年4月 ～ 継続中

  • 電気化学会 電解技術委員会　委員

    2018年8月 ～ 継続中

  • 燃料電池開発情報センター　シンポジウム委員会 委員

    2018年7月 ～ 継続中

  • 燃料電池開発情報センター　学術委員

    2018年4月 ～ 継続中

  • 公益社団法人 日本金属学会　触媒材料の金属学研究会：委員

    2017年3月 ～ 継続中

  • 電池技術委員会　委員

    2015年2月 ～ 継続中

  • 電気化学会第90回大会　実行委員

    2023年3月 ～ 2023年3月

  • 日本金属学会　まてりあ編集委員

    2019年4月 ～ 2023年3月

︎全件表示 ︎最初の5件までを表示

所属学協会 7

  • ナノ学会

    2021年6月 ～ 継続中

  • 触媒学会

  • 日本鉄鋼協会

  • International Society of Electrochemistry

  • The Electrochamical Society

  • 金属学会

  • 電気化学会

︎全件表示 ︎最初の5件までを表示

研究キーワード 5

  • CO2電解

  • 水電解

  • 燃料電池

  • 分子線エピタキシ

  • 電極触媒

研究分野 4

  • 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 / 複合材料、界面 /

  • ナノテク・材料 / 材料加工、組織制御 / 電極触媒

  • ナノテク・材料 / ナノ構造化学 /

受賞 15

  1. 工業電解奨励賞

    2023年11月　電解科学技術委員会

  2. 第44回本多記念奨励賞

    2023年5月　本多記念会　表面ナノ構造制御による電気化学エネルギー・物質変換触媒の開発

  3. 第19回村上奨励賞

    2022年9月　日本金属学会　表面原子・ナノ構造制御による電極触媒材料の高機能化に関する研究

  4. 令和元年度FCDIC顕彰制度 奨励賞

    2020年5月　燃料電池開発情報センター

  5. 第19回インテリジェント・コスモス奨励賞

    2020年5月　インテリジェントコスモス学術振興財団

  6. 第8回研究開発奨励賞

    2019年10月　一般社団法人エヌエフ基金

  7. 第59回原田研究奨励賞

    2019年6月　本田記念会

  8. 日本金属学会「奨励賞」

    2018年9月　日本金属学会

  9. トーキン科学技術賞 「トーキン財団奨励賞」

    2018年3月　トーキン科学技術振興財団

  10. 電池技術委員会賞

    2014年11月20日　電池技術委員会

  11. Poster Presentation Award

    2014年3月　Annual Meeting of Excellent Graduate Schools

  12. Student Poster Awards 1st Place：Pacific Rim Meeting on Electrochemical and Solid-State Science (PRiME 2012)

    2012年10月10日　Pacific Rim Meeting on Electrochemical and Solid-State Science (PRiME 2012)

  13. ポスター賞：電気化学会第第79回大会

    2012年3月29日　日本電気化学会燃料電池研究会・SOFC研究会

  14. Outstanding Poster Presentation for Young Scientists

    2011年12月　KINKEN WAKATE 2011

  15. Outstanding Poster Presentation For Young Scientists

    2011年12月　International Symposium of Materials Integration In conjunction with the 2nd International Symposium on Advanced Synthesis and Processing Technology for Materials (ASPT2011) KINKEN WAKATE

︎全件表示 ︎最初の5件までを表示

論文 75

  1. Impact of Applied Potential Range on Corrosion Behavior of Stainless Steel Oxygen Evolution Electrode Under Potential Cycle Loading

    Naoto Todoroki, Toshimasa Wadayama

    SSRN　2024年4月

    出版者・発行元：Elsevier BV

    DOI： 10.2139/ssrn.4780625 　

  2. Oxygen Reduction Reaction Activity Enhancement of Dry-Process-Synthesized Pt(111)/Nb:SnO<sub>2</sub>(101)/Pt(111) Coherent Lattice Stacking Model Catalyst Surface 査読有り

    Yoshihiro Chida, Hikaru Kamikawa, Naoto Todoroki, Toshimasa Wadayama

    MATERIALS TRANSACTIONS　2　(65)　125-129　2024年2月

    出版者・発行元：Japan Institute of Metals

    DOI： 10.2320/matertrans.mt-m2023172 　

    ISSN：1345-9678

    eISSN：1347-5320

  3. Pt-Surface Stabilization by High-Entropy Alloys for Enhancing Oxygen Reduction Reaction Property: Single-Crystal Model Catalyst Study 査読有り

    Yoshihiro Chida, Takeru Tomimori, Naoto Todoroki, Toshimasa Wadayama

    Electrochemistry Communications　107657-107657　2023年12月

    出版者・発行元：Elsevier BV

    DOI： 10.1016/j.elecom.2023.107657 　

    ISSN：1388-2481

  4. Kinetically Controlled Direct Synthesis of B2- and A1-Structured Cu–Pd Nanoparticles

    Masanao Ishijima, Naoto Todoroki, Jhon L. Cuya Huaman, Yuto Tanaka, Jeyadevan Balachandran

    Inorganic Chemistry　62　(47)　19270-19278　2023年11月10日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acs.inorgchem.3c02766 　

    ISSN：0020-1669

    eISSN：1520-510X

  5. 再生可能エネルギーを直接利用する水電解技術：再生可能エネルギーの電力変動が電解槽の耐久性に及ぼす影響 査読有り

    小島宏一, 長澤兼作, 轟直人, 伊藤良一, 松井敏明, 中島良

    水素エネルギーシステム　48　(3)　189-213　2023年10月

  6. Suppressed Hydrogen Peroxide Generation and Enhanced Electrochemical Hydrogen Oxidation Activity for Tungsten-Oxide-Modified Platinum Surface Model Catalyst System 査読有り

    Kenta Hayashi, Hikaru Kamikawa, Naoto Todoroki, Toshimasa Wadayama

    MATERIALS TRANSACTIONS　64　(10)　2431-2439　2023年10月1日

    出版者・発行元：Japan Institute of Metals

    DOI： 10.2320/matertrans.mt-mh2022004 　

    ISSN：1345-9678

    eISSN：1347-5320

  7. Improving the Oxygen Evolution Activity and Stability of Nb-Doped TiO<sub>2</sub>-Supported RuO<sub>2</sub> by a SnO<sub>2</sub> Interlayer: A Model Catalyst Study on Single-Crystal Oxide Heterostructures 査読有り

    Naoto Todoroki, Ryutaro Kudo, Kenta Hayashi, Mizuho Yokoi, Naomi Naraki, Toshimasa Wadayama

    ACS Catalysis　(13)　11433-11440　2023年8月15日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acscatal.3c01525 　

    ISSN：2155-5435

    eISSN：2155-5435

  8. Experimental study platform for electrocatalysis of atomic-level controlled high-entropy alloy surfaces 査読有り

    Yoshihiro Chida, Takeru Tomimori, Tomoaki Ebata, Noboru Taguchi, Tsutomu Ioroi, Kenta Hayashi, Naoto Todoroki, Toshimasa Wadayama

    Nature Communications　14　(1)　2023年7月26日

    出版者・発行元：Springer Science and Business Media LLC

    DOI： 10.1038/s41467-023-40246-5 　

    eISSN：2041-1723

    詳細を見る 詳細を閉じる

    Abstract High-entropy alloys (HEAs) have attracted considerable attention to improve performance of various electrocatalyst materials. A comprehensive understanding of the relationship between surface atomic-level structures and catalytic properties is essential to boost the development of novel catalysts. In this study, we propose an experimental study platform that enables the vacuum synthesis of atomic-level-controlled single-crystal high-entropy alloy surfaces and evaluates their catalytic properties. The platform provides essential information that is crucial for the microstructural fundamentals of electrocatalysis, i.e., the detailed relationship between multi-component alloy surface microstructures and their catalytic properties. Nanometre-thick epitaxially stacking layers of Pt and equi-atomic-ratio Cr-Mn-Fe-Co-Ni, the so-called Cantor alloy, were synthesised on low-index single-crystal Pt substrates (Pt/Cr-Mn-Fe-Co-Ni/Pt(hkl)) as a Pt-based single-crystal alloy surface model for oxygen reduction reaction (ORR) electrocatalysis. The usefulness of the platform was demonstrated by showing the outperforming oxygen reduction reaction properties of high-entropy alloy surfaces when compared to Pt-Co binary surfaces.

  9. Composition sensitive selectivity and activity of electrochemical carbon dioxide reduction on Pd–Cu solid-solution alloy nanoparticles 査読有り

    Naoto Todoroki, Masanao Ishijima, Jhon L. Cuya Huaman, Yuto Tanaka, Jeyadevan Balachandran

    Catalysis Science &amp; Technology　13　(17)　5025-5032　2023年7月

    出版者・発行元：Royal Society of Chemistry (RSC)

    DOI： 10.1039/d3cy00748k 　

    ISSN：2044-4753

    eISSN：2044-4761

    詳細を見る 詳細を閉じる

    The alloy-composition-sensitive selectivity and activity of CO<sub>2</sub>RR have been demonstrated for Pd-Cu solid solution nanopaticles.

  10. Suppression of Catalyst Layer Detachment by Interfacial Microstructural Modulation of the NiCo<sub>2</sub>O<sub>4</sub>/Ni Oxygen Evolution Electrode for Renewable Energy-Powered Alkaline Water Electrolysis 査読有り

    Naoto Todoroki, Kensaku Nagasawa, Hayato Enjoji, Shigenori Mitsushima

    ACS Applied Materials &amp; Interfaces　15　(20)　24399-24407　2023年5月9日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acsami.3c01572 　

    ISSN：1944-8244

    eISSN：1944-8252

  11. Surface modification of gold by carbazole dendrimers for improved carbon dioxide electroreduction 査読有り

    Sota Yoshida, Masaki Sampei, Naoto Todoroki, Eri Hisamura, Kohei Nakao, Ken Albrecht, Toshimasa Wadayama

    Chemical Communications　(59)　3459-3462　2023年2月

    出版者・発行元：Royal Society of Chemistry (RSC)

    DOI： 10.1039/d3cc00350g 　

    ISSN：1359-7345

    eISSN：1364-548X

    詳細を見る 詳細を閉じる

    Surface modification by carbazole dendrimers, in particular, 9-phenylcarbazole, enhances electrochemical CO<sub>2</sub> conversion to CO on gold.

  12. Influence of renewable energy power fluctuations on water electrolysis for green hydrogen production 査読有り

    Hirokazu Kojima, Kensaku Nagasawa, Naoto Todoroki, Yoshikazu Ito, Toshiaki Matsui, Ryo Nakajima

    International Journal of Hydrogen Energy　48　(12)　4572-4593　2023年2月

    出版者・発行元：Elsevier BV

    DOI： 10.1016/j.ijhydene.2022.11.018 　

    ISSN：0360-3199

    詳細を見る 詳細を閉じる

    The development of renewable energy technologies is essential to achieve carbon neutrality. Hydrogen can be stably stored and transported in large quantities to maximize power utilization. Detailed understanding of the characteristics and operating methods of water electrolysis technologies, in which naturally intermittent fluctuating power is used directly, is required for green hydrogen production, because fluctuating power-driven water electrolysis processes significantly differ from industrial water electrolysis processes driven by steady grid power. Thus, it is necessary to overcome several issues related to the direct use of fluctuating power. This article reviews the characteristics of fluctuating power and its generation as well as the current status and issues related to the operation conditions, water electrolyzer configuration, system requirements, stack/catalyst durability, and degradation mechanisms under the direct use of fluctuating power sources. It also provides an accelerated degradation test protocol method for fair catalyst performance comparison and share of effective design directions. Finally, it discusses potential challenges and recommendations for further improvements in water electrolyzer components and systems suitable for practical use, suggesting that a breakthrough could be realized toward the achievement of a sustainable hydrogen-based society.

  13. Stainless Steel Anode for Alkaline Water Electrolysis: Recent Progress in Active and Durable Surface Catalyst Layer Generation 招待有り 査読有り

    Naoto Todoroki, Toshimasa Wadayama

    MATERIALS TRANSACTIONS　64　(10)　2376-2385　2023年1月20日

    出版者・発行元：Japan Institute of Metals

    DOI： 10.2320/matertrans.mt-mh2022002 　

    ISSN：1345-9678

    eISSN：1347-5320

  14. Enhanced electrochemical hydrogen oxidation reaction and suppressed hydrogen peroxide generation properties on Pt/Ir(111) bimetallic surfaces

    Kenta Hayashi, Takeru Tomimori, Riku Sato, Naoto Todoroki, Toshimasa Wadayama

    Physical Chemistry Chemical Physics　25　(4)　2770-2775　2023年

    出版者・発行元：Royal Society of Chemistry (RSC)

    DOI： 10.1039/d2cp05430b 　

    ISSN：1463-9076

    eISSN：1463-9084

    詳細を見る 詳細を閉じる

    A Pt<sub>0.3ML</sub>/Ir(111) model catalyst showed desirable properties for a polymer electrolyte fuel cell anode, including enhanced hydrogen oxidation activity and suppressed H<sub>2</sub>O<sub>2</sub> generation.

  15. Surface microstructures and oxygen evolution properties of cobalt oxide deposited on Ir(111) and Pt(111) single crystal substrates

    Naoto Todoroki, Hiroto Tsurumaki, Arata Shinomiya, Toshimasa Wadayama

    Electrochemical Science Advances　3　(6)　2022年9月11日

    出版者・発行元：Wiley

    DOI： 10.1002/elsa.202200007 　

    ISSN：2698-5977

    eISSN：2698-5977

    詳細を見る 詳細を閉じる

    Abstract We investigated the oxygen evolution reaction (OER) activity changes of cobalt oxide (CoO<sub>x</sub>) thin films on Ir(111) and Pt(111) substrates by repeated OER measurements in 0.1 M KOH. Atomic force microscopy and X‐ray photoelectron spectroscopy analysis of the as‐prepared CoO<sub>x</sub>/Ir(111) and CoO<sub>x</sub>/Pt(111) showed similar surface morphologies of the CoO<sub>x</sub> thin films and almost the same OER overpotentials, which were estimated to be around 430 mV. However, after three OER measurements, the overpotential of CoO<sub>x</sub>/Ir(111) decreased by 70 mV, whereas that of CoO<sub>x</sub>/Pt(111) increased slightly. Structural analysis showed that CoO<sub>x</sub>/Ir(111) revealed the island‐like nanostructures of CoO<sub>x</sub> dispersed on Ir(111) surface, accompanied by the generation of CoOOH. In contrast, for CoO<sub>x</sub>/Pt(111), the Pt(111) substrate remains covered by the CoO<sub>x</sub> thin film. The results suggest that the interaface at CoO<sub>x</sub> (CoOOH) nano‐islands and Ir(111) substrate are responsible for reducing the OER overpotential.

  16. Dissolution of constituent elements from various austenitic stainless steel oxygen evolution electrodes under potential cycle loadings 査読有り

    Naoto Todoroki, Toshimasa Wadayama

    International Journal of Hydrogen Energy　47　(77)　32753-32762　2022年8月

  17. Hydrogen peroxide generation and hydrogen oxidation reactions of vacuum-prepared Ru/Ir(111) bimetallic surfaces 査読有り

    Kenta Hayashi, Keisuke Kusunoki, Takeru Tomimori, Riku Sato, Naoto Todoroki, Toshimasa Wadayama

    Physical Chemistry Chemical Physics　24　(23)　14277-14283　2022年5月

    出版者・発行元：Royal Society of Chemistry (RSC)

    DOI： 10.1039/d2cp01261h 　

    ISSN：1463-9076

    eISSN：1463-9084

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    The electrochemical hydrogen oxidation reaction activity of a well-defined Ir–Ru bimetallic surface alloy is closely related to Ir/Ru atomic ratios and Ir-dimer (Ir<sub>2</sub>) and/or trimer (Ir<sub>3</sub>) ensemble probability at the topmost surface.

  18. Activity switching of Sn and In species in Heusler alloys for electrochemical CO<sub>2</sub> reduction 査読有り

    Kazuyuki Iwase, Takayuki Kojima, Naoto Todoroki, Itaru Honma

    Chemical Communications　58　(31)　4865-4868　2022年3月

    出版者・発行元：Royal Society of Chemistry (RSC)

    DOI： 10.1039/d2cc00754a 　

    ISSN：1359-7345

    eISSN：1364-548X

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    The electrochemical CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) activity of Ni<sub>2</sub>MnIn and Ni<sub>2</sub>MnSn Heusler alloys was investigated. This is the first report that shows the CO<sub>2</sub>RR activity of Heusler alloy particles.

  19. Nanostructures and Oxygen Evolution Overpotentials of Surface Catalyst Layers Synthesized on Various Austenitic Stainless Steel Electrodes 査読有り

    Naoto Todoroki, Arata Shinomiya, Toshimasa Wadayama

    Electrocatalysis　13　(2)　116-125　2022年3月

    出版者・発行元：Springer Science and Business Media LLC

    DOI： 10.1007/s12678-022-00705-x 　

    ISSN：1868-2529

    eISSN：1868-5994

  20. Abnormal Metal Bond Distances in PtAu Alloy Nanoparticles: In Situ Back-Illumination XAFS Investigations of the Structure of PtAu Nanoparticles on a Flat HOPG Substrate Prepared by Arc Plasma Deposition 査読有り

    Bing Hu, Bapurao Bharate, Juan D. Jimenez, Jochen Lauterbach, Naoto Todoroki, Toshimasa Wadayama, Kotaro Higashi, Tomoya Uruga, Yasuhiro Iwasawa, Hiroko Ariga-Miwa, Satoru Takakusagi, Kiyotaka Asakura

    The Journal of Physical Chemistry C　126　(2)　1006-1016　2022年1月10日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acs.jpcc.1c08393 　

    ISSN：1932-7447

    eISSN：1932-7455

  21. Oxygen reduction reaction properties of vacuum-deposited Pt on thermally grown epitaxial graphene layers 査読有り

    Masashi Watanabe, Takafumi Kanauchi, Yoshihiro Chida, Kenta Hayashi, Naoto Todoroki, Toshimasa Wadayama

    Journal of Vacuum Science & Technology A　40　(1)　013216-013216　2022年1月

    出版者・発行元：American Vacuum Society

    DOI： 10.1116/6.0001379 　

    ISSN：0734-2101

    eISSN：1520-8559

  22. Hydrogen Peroxide Generation and Hydrogen Oxidation Reaction Properties of Ir(111)-, (100)-, and (110)-Low-Index Single-Crystal Surfaces 査読有り

    Kenta Hayashi, Takeru Tomimori, Yoshihiro Chida, Naoto Todoroki, Toshimasa Wadayama

    The Journal of Physical Chemistry C　125　(39)　21481-21487　2021年9月29日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acs.jpcc.1c07322 　

    ISSN：1932-7447

    eISSN：1932-7455

  23. Atomically resolved interface structures of vacuum-deposited Pt on SnO2 (110), (101), and (111) 査読有り

    Yoshihiro Chida, Naoto Todoroki, Toshimasa Wadayama

    Journal of Vacuum Science & Technology A　(39)　053411　2021年9月

  24. Activity for the ORR on Pt-Pd-Co ternary alloy electrodes is markedly affected by surface structure and composition 査読有り

    Mashu Torihata, Masashi Nakamura, Naoto Todoroki, Toshimasa Wadayama, Nagahiro Hoshi

    Electrochemistry Communications　125　107007-107007　2021年3月

    出版者・発行元：Elsevier BV

    DOI： 10.1016/j.elecom.2021.107007 　

    ISSN：1388-2481

  25. Oxygen Reduction Reaction of Third Element-Modified Pt/Pd(111): Effect of Atomically Controlled Ir Locations on the Activity and Durability 査読有り

    Keisuke Kusunoki, Daisuke Kudo, Kenta Hayashi, Yoshihiro Chida, Naoto Todoroki, Toshimasa Wadayama

    ACS Catalysis　11　(3)　1554-1562　2021年2月5日

    出版者・発行元：American Chemical Society (ACS)

    DOI： 10.1021/acscatal.0c04054 　

    ISSN：2155-5435

    eISSN：2155-5435

  26. Electrochemical stability of stainless-steel-made anode for alkaline water electrolysis: Surface catalyst nanostructures and oxygen evolution overpotentials under applying potential cycle loading 査読有り

    Naoto Todoroki, Toshimasa Wadayama

    Electrochemistry Communications　122　106902-106902　2021年1月

    出版者・発行元：None

    DOI： 10.1016/j.elecom.2020.106902 　

    ISSN：1388-2481

  27. Dry synthesis of single-nanometer-scale Pt Si fine particles for electrocatalysis 査読有り

    Naoto Todoroki, Shuntaro Takahashi, Kotaro Kawaguchi, Yusuke Fugane, Toshimasa Wadayama

    Journal of Electroanalytical Chemistry　114492-114492　2020年7月

    出版者・発行元：Elsevier BV

    DOI： 10.1016/j.jelechem.2020.114492 　

    ISSN：1572-6657

  28. Online Electrochemical Mass Spectrometry Combined with the Rotating Disk Electrode Method for Direct Observations of Potential-Dependent Molecular Behaviors in the Electrode Surface Vicinity 査読有り

    Naoto Todoroki, Hiroto Tsurumaki, Hiroki Tei, Tomohiro Mochizuki, Toshimasa Wadayama

    Journal of The Electrochemical Society　167　(10)　106503-106503　2020年6月11日

    出版者・発行元：The Electrochemical Society

    DOI： 10.1149/1945-7111/ab9960 　

    eISSN：1945-7111

  29. Model building analysis – a novel method for statistical evaluation of Pt L3-edge EXAFS data to unravel the structure of Pt-alloy nanoparticles for the oxygen reduction reaction on highly oriented pyrolytic graphite 査読有り

    F. E. Feiten, S. Takahashi, O. Sekizawa, Y. Wakisaka, T. Sakata, N. Todoroki, T. Uruga, T. Wadayama, Y. Iwasawa, K. Asakura

    Physical Chemistry Chemical Physics　2020年

    出版者・発行元：None

    DOI： 10.1039/c9cp06891k 　

    ISSN：1463-9076

    eISSN：1463-9084

  30. Heterolayered Ni–Fe Hydroxide/Oxide Nanostructures Generated on a Stainless-Steel Substrate for Efficient Alkaline Water Splitting 査読有り

    Naoto Todoroki, Toshimasa Wadayama

    ACS Applied Materials & Interfaces　(11)　44161-44169　2019年10月

  31. Ligand-Effect-Induced Oxygen Reduction Reaction Activity Enhancement for Pt/Zr/Pt(111) Surfaces with Tensile Strain Relieved by Stacking Faults 査読有り

    Daisuke Kudo, Soma Kaneko, Rikiya Myochi, Yoshihiro Chida, Naoto Todoroki, Tadao Tanabe, Toshimasa Wadayama

    ACS Applied Energy Materials　2　(7)　4597-4601　2019年6月

    出版者・発行元：None

    DOI： 10.1021/acsaem.9b00873 　

    ISSN：2574-0962

  32. Electrochemical CO2 Reduction on Bimetallic Surface Alloys: Enhanced Selectivity to CO for Co/Au(110) and to H2 for Sn/Au(110) 査読有り

    Naoto Todoroki, Hiroki Tei, Taku Miyakawa, Hiroto Tsurumaki, Toshimasa Wadayama

    ChemElectroChem　6　(12)　3101-3107　2019年6月

  33. Effective Surface Termination with Au on PtCo@Pt Core-Shell Nanoparticle: Microstructural Investigations and Oxygen Reduction Reaction Properties 査読有り

    Shuntaro Takahashi, Naoto Todoroki, Rikiya Myochi, Tetsuro Nagao, Noboru Taguchi, Tsutomu Ioroi, Felix E. Feiten, Yuki Wakisaka, Kiyotaka Asakura, Oki Sekizawa, Tomohiro Sakata, Kotaro Higashi, Tomoya Uruga, YasuhiroIwasawa, Toshimasa Wadayama

    Journal of Electroanalytical Chemistry　842　(1)　1-7　2019年6月

    DOI： 10.1016/j.jelechem.2019.04.053 　

    ISSN：1572-6657

  34. Oxygen Reduction Reaction Activity of Nano-Flake Carbon-Deposited Pt75Ni25(111) Surfaces 査読有り

    Naoto Todoroki, Ren Sasakawa, Keisuke Kusunoki, Toshimasa Wadayama

    Electrocatalysis　2019年2月

    DOI： 10.1007/s12678-019-00517-6 　

  35. Surface Atomic Arrangement Dependence of Electrochemical CO2 Reduction on Gold: Online Electrochemical Mass Spectrometric Study on Low-Index Au(hkl) Surfaces 査読有り

    N. Todoroki, H. Tei, H. Tsurumaki, T.Miyakawa, T. Inoue, T. Wadayama

    ACS Catalysis　9　1383-1388　2019年1月

  36. Oxygen Reduction and Oxygen Evolution Reaction Activity on Co/Pt (111) Surfaces in Alkaline Solution 査読有り

    ECS Transactions　86　(13)　569-574　2018年10月

    DOI： 10.1149/08613.0569ecst 　

  37. Oxygen Reduction Reaction Properties for Dry-Process Synthesized Pt/TaCx Nanoparticles 査読有り

    ECS Transactions　86　(13)　519-524　2018年10月

    DOI： 10.1149/08613.0519ecst 　

  38. Rotating Disk Electrode–Online Electrochemical Mass Spectrometry for Oxygen Reduction Reaction on Pt Electrode Surfaces 査読有り

    ECS Transaction　86　(13)　447-452　2018年10月

    DOI： 10.1149/08613.0447ecst 　

  39. Oxygen Reduction Reaction Properties of Dry-Process-Synthesized Pt/Graphene/SiC (0001) Model Catalyst Surfaces 査読有り

    ECS Transactions　86　(13)　525-530　2018年10月

    DOI： 10.1149/08613.0525ecst 　

  40. Oxygen Reduction Reaction Activity for Cobalt-Deposited Pt (111) Model Catalyst Surfaces in Alkaline Solution 査読有り

    N. Todoroki, T. Wadayama

    Electrochemistry　86　(5)　243-245　2018年9月

    DOI： 10.5796/electrochemistry.18-00024 　

  41. 歪み制御した単結晶Ptシェルの酸素還元反応活性 招待有り 査読有り

    金子聡真, 妙智力也, 渡邉裕文, 番土陽平, 高橋俊太郎, 轟直人, 田邉匡生, 和田山智正

    燃料電池　18　73-79　2018年8月

  42. Alloy-composition-dependent oxygen reduction reaction activity and electrochemical stability of Pt-based bimetallic systems: a model electrocatalyst study of Pt/PtxNi100−x(111) 査読有り

    Naoto Todoroki, Ryutaro Kawamura, Masato Asano, Ren Sasakawa, Shuntaro Takahashi, Toshimasa Wadayama

    Physical Chemistry Chemical Physics　20　(17)　11994-12004　2018年

    出版者・発行元：Royal Society of Chemistry ({RSC})

    DOI： 10.1039/c8cp01217b 　

    ISSN：1463-9076

  43. Ultrahigh Vacuum Synthesis of Strain-Controlled Model Pt (111)-Shell Layers: Surface Strain and Oxygen Reduction Reaction Activity 査読有り

    S. Kaneko, R. Myochi, S. Takahashi, N. Todoroki, T. Wadayama, T. Tanabe

    The Journal of Physical Chemistry Letters　8　(21)　5360-5365　2017年10月

  44. Communication—Electrochemical Stability of Pt/Pd (111) Model Core-Shell Structure in 80° C Perchloric Acid 査読有り

    N. Todoroki, Y. Bando, Y. Tani, S. Kaneko, H. Watanabe, S. Takahashi, T. Wadayama

    Journal of The Electrochemical Society　164　(9)　F908-F910　2017年

    出版者・発行元：None

    DOI： 10.1149/2.0571709jes 　

    ISSN：0013-4651

    eISSN：1945-7111

  45. Highly Enhanced Oxygen Reduction Reaction Activity and Electrochemical Stability of Pt/Ir(111) Bimetallic Surfaces 査読有り

    Naoto Todoroki, Hirofumi Watanabe, Takayuki Kondo, Soma Kaneko, Toshimasa Wadayama

    ELECTROCHIMICA ACTA　222　1616-1621　2016年12月

    出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

    DOI： 10.1016/j.electacta.2016.11.149 　

    ISSN：0013-4686

    eISSN：1873-3859

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    We demonstrate highly enhanced ORR activity and electrochemical stability of Pt/Ir(111) model core-shell catalysts prepared by molecular beam epitaxy (MBE) in ultra-high vacuum (UHV). Reflection high-energy electron diffraction patterns for the surfaces show that Pt grew epitaxially on the clean Ir(111) substrate and the corresponding scanning tunneling microscope images collected in UHV reveal atomically flat terraces with 50-80 nm widths at a substrate temperature of 673 K. In contrast, the corresponding surfaces prepared at a substrate temperature of 303 K show island-like topmost surface structures. The two-monolayer (ML)-thick Pt grown on Ir(111) (Pt-2ML/Ir(111)) surfaces, prepared at substrate temperatures of 303 K and 673 K, show ca. 6 and 24 times higher ORR activities than clean Pt(111), respectively. The anomalous activity enhancement for the latter surface prepared at 673 K is probably caused by homogeneous surface strain acting on the Pt shells that is derived from the 2.2% lattice mismatch between the Pt and Ir. The preparation-temperature-dependent ORR activity suggests that the activity can be dominated by the topmost surface and interface structures of the Pt shell-Ir(111) bimetallic system. Furthermore, while the initial ORR activity of pristine surfaces decreases with increasing Pt shell thickness, the stability during room temperature potential cycling between 0.6 and 1.0V in a 0.1 M HClO4 solution was greatly enhanced above three ML thickness; the Pt-4ML/Ir(111) surface prepared at 673 K retained 6.5 times higher ORR activity than Pt(111), even after 5000 potential cycles. The ORR activity and electrochemical stabilities for the Pt/Ir(111) bimetallic surfaces are the highest among the MBE-prepared Pt/M(111) (M = Ir, Pd, Au) systems reported to date. The results obtained in this study show that Pt/Ir core-shell nanostructures are potential candidates for highly active and durable ORR catalysts. (C) 2016 Elsevier Ltd. All rights reserved.

  46. Dealloying of Nitrogen-Introduced Pt–Co Alloy Nanoparticles: Preferential Core–Shell Formation with Enhanced Activity for Oxygen Reduction Reaction 査読有り

    S. Takahashi, N. Takahashi, N. Todoroki, T. Wadayama

    ACS Omega　1　(6)　1247-1252　2016年12月

  47. ORR activity and electrochemical stability for well-defined topmost and interface structures of the Pt/Pd(111) bimetallic system 査読有り

    Naoto Todoroki, Yohe Bando, Hirofumi Watanabe, Yuki Tani, Toshimasa Wadayama

    ELECTROCHIMICA ACTA　212　822-827　2016年9月

    出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

    DOI： 10.1016/j.electacta.2016.07.068 　

    ISSN：0013-4686

    eISSN：1873-3859

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    We investigated oxygen reduction reaction (ORR) activity and electrochemical stability of Pt/Pd(111) model electrocatalysts having well-defined topmost and sub-surface structures. The Pt/Pd(111) bimetallic surfaces were prepared by vacuum-deposition of Pt on clean Pd(111) at substrate temperatures of x (x-Pt-ynm/Pd(111), where x = 573 K or 673 K, y = 0.6 or 1.2) in ultra-high vacuum (UHV). Reflection high-energy electron diffraction patterns and UHV scanning tunneling microscopy images revealed that Pt grew epitaxially on the Pd(111) substrate under the aforementioned Pt deposition conditions. High substrate temperatures resulted in thermal diffusion of deposited Pt with substrate Pd atoms. The Pt atomic ratio at the topmost surface of 573K-Pt-0.6nm/Pd(111) is estimated to be 95% using He-ion scattering spectroscopy (ISS), which is 8% greater than that of 673K-Pt-0.6nm/Pd(111). ORR activities of the 573K-Pt-0.6nm/Pd(111) and 673K-Pt-0.6nm/Pd(111) surfaces were 6.3 and 3.6 times higher than that of clean Pt (111), respectively, indicating that the activity is sensitive to the topmost surface Pt atomic ratios. Moreover, electrochemical stability of 573K-Pt-0.6nm/Pd(111) evaluated under potential cycle loadings (0.6V-1.0 V) is better than that of 673K-Pt-0.6nm/Pd(111). Depth profiles of the surfaces judged by corresponding ISS spectra suggest that the stability stems not only from the topmost Pt atomic ratios but also effective Pt-shell thickness determined by thermal diffusion of Pt and Pd. Furthermore, an increase in Pt-thickness from 0.6 nm to 1.2 nm improved the electrochemical stability: 573K-Pt-1.2nm/Pd(111) retained 5 times more activity vs. clean Pt(111) even after 2000 potential cycles, at which the activity of 573K-Pt-0.6nm/Pd(111) was the same as that for initial activity of clean Pt(111). The results obtained in this study demonstrate that atomic-level structures Pt-Pd bimetallic alloy surfaces determine the ORR activity and electrochemical stability of practical Pd@Pt core-shell catalysts. (C) 2016 Published by Elsevier Ltd.

  48. Oxygen Reduction Reaction Activity for Strain-Controlled Pt-Based Model Alloy Catalysts: Surface Strains and Direct Electronic Effects Induced by Alloying Elements 査読有り

    Masato Asano, Ryutaro Kawamura, Ren Sasakawa, Naoto Todoroki, Toshimasa Wadayama

    ACS CATALYSIS　6　(8)　5285-5289　2016年8月

    出版者・発行元：AMER CHEMICAL SOC

    DOI： 10.1021/acscatal.6b01466 　

    ISSN：2155-5435

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    Surface strain and electronic interactions (i.e., strain and ligand effects) play key roles in enhancing the oxygen reduction reaction (ORR) catalytic activity of Pt-based alloy catalysts. Herein, we evaluate the ORR activity enhancement factors for Pt(111)-shell layers on Pt25Ni75(111) single-crystal surfaces prepared by molecular beam epitaxy under ultrahigh vacuum (UHV). Scanning tunneling microscopy images of the pristine surfaces collected under UHV revealed periodic surface modulations, known as Moire patterns, suggesting that the topmost Pt(111)-shell layers are compressively strained by the influence of the underlying Ni atoms. The correlation between the ORR activities and estimated strains for 3-ML- and 4-ML-thick Pt shells (where ML represents monolayer), each having -1.7% and -1.2% strained Pt-shells, correspond well to the strain-based theory predictions. On the other hand, a 2-ML-thick Pt shell, with -2.8% strain, exhibits a remarkable ORR activity enhancement, i.e., 25 times higher than the pristine Pt(111): the enhancement factor anomalously deviates from the value predicted by the strain-based theory. Therefore, the activity enhancement of the 2-ML-thick Pt sample can be ascribed to a ligand effect induced by the Ni atoms just below the topmost Pt(111)-shell layer. The results obtained in this study provide a fundamental insight into the ORR activity enhancement mechanisms of Pt-based electrocatalysts.

  49. Electrochemical Reduction of CO2 on Ni- and Pt-Epitaxially Grown Cu(111) Surfaces 査読有り

    Naoto Todoroki, Naohiro Yokota, Shoko Nakahata, Hiroki Nakamura, Toshimasa Wadayama

    ELECTROCATALYSIS　7　(1)　97-103　2016年1月

    出版者・発行元：SPRINGER

    DOI： 10.1007/s12678-015-0286-6 　

    ISSN：1868-2529

    eISSN：1868-5994

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    The electroreduction of CO2 on well-defined M/Cu(111) (M= Ni and Pt) bimetallic surface systems fabricated using molecular beam epitaxy was studied. The total faradic efficiency for CO2 reduction using one-monolayer (ML)-thick Pt epitaxially grown on a Cu(111) substrate (1-ML Pt/Cu(111)) was nearly the same as that for clean Pt(111). In contrast, the 1-ML-thick Ni/Cu(111) system exhibited increased selectivity for CH4 production compared with that of clean Ni(111), which may stem from the geometric tensile strain induced by the underlying Cu(111) substrate. Notably, bimetallic surfaces consisting of 0.1-ML-thick Ni or Pt grown on Cu(111) exhibited significantly different reduction behaviors compared with those of Cu because of the presence of the a small amount of epitaxially grown metal. For the 0.1-ML-thick Ni/Cu(111) system, the total faradaic efficiency for CO2 reduction and the production rate for CO were enhanced compared with those for clean Cu(111), whereas the production of CH4 decreased. In contrast, the total faradaic efficiency was significantly suppressed for the 0.1-ML-thick Pt/Cu(111) bimetallic substrate, with only a very small amount of CH4 production. The difference in the catalytic properties is attributed to the difference in the adsorption energies for CO, which is an intermediate in the electrochemical production of CH4 and C2H4.

  50. Oxygen Reduction Reaction Activity and Durability for Model Pt Shell Layers on Ir(111) Prepared by Molecular Beam Epitaxy 査読有り

    H. Watanabe, S. Kaneko, N. Todoroki, T. Wadayama

    POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　815-820　2016年

    出版者・発行元：ELECTROCHEMICAL SOC INC

    DOI： 10.1149/07514.0815ecst 　

    ISSN：1938-5862

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    We fabricated well-defined Pt-Ir bimetallic surfaces through monolayer-thick Pt epitaxial growth on Ir(111) substrates (Pt-nML/Ir(111): n = 1-4) using molecular beam epitaxy in ultrahigh vacuum (UHV). The surface structures of Pt-nML/Ir(111) were verified using reflection high-energy electron diffraction in UHV. Electrochemical characterization tests, including evaluations of oxygen reduction reaction (ORR) activity and durability, were performed using cyclic voltammetry and rotating disk electrode techniques in 0.1 M HClO4. Regarding the initial ORR activity for Pt-nML/Ir(111) surfaces, Pt-2ML/Ir(111) surfaces exhibited the highest ORR activity (24 times that of the clean Pt(111) surfaces). Initial ORR activities declined when square-wave potential cycles (PCs) were applied between 0.6 and 1.0 V vs. reversible hydrogen electrode. The Pt-4ML/Ir(111) surface exhibited the highest ORR activity even after 5000 PC loadings (6 times that of the clean Pt(111) surfaces), suggesting that Pt-shell/Ir-core core-shell nanoparticles have potential for use as practical Pt-based bimetallic ORR catalysts.

  51. Pt-Ni Nanoparticle-Stacking Thin Film: Highly Active Electrocatalysts for Oxygen Reduction Reaction 査読有り

    Naoto Todoroki, Takashi Kato, Takehiro Hayashi, Shuntaro Takahashi, Toshimasa Wadayama

    ACS CATALYSIS　5　(4)　2209-2212　2015年4月

    出版者・発行元：AMER CHEMICAL SOC

    DOI： 10.1021/acscatal.5b00065 　

    ISSN：2155-5435

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    A novel nanoparticle-stacking thin film (NPSTF) of Pt-Ni alloy for highly active oxygen reduction reaction (ORR) electrocatalyst was synthesized. The Pt mass activity of the synthesized Pt-Ni NPSTF were 10-fold higher than commercial carbon-supported Pt catalysts. The remarkable ORR activity enhancement of the Pt-Ni NPSTF was attributed to the modified electronic properties of the surface Pt-enriched layers induced by underlying Ni atoms and to the increased active surface area achieved by stacking of Pt-Ni nanoparticles.

  52. Electrochemical structural stability of au-modified Pt nanoparticles prepared by arc-plasma deposition 査読有り

    Shuntaro Takahashi, Hiroshi Chiba, Naoto Todoroki, Toshimasa Wadayama

    ECS Transactions　69　(17)　657-661　2015年

    出版者・発行元：Electrochemical Society Inc.

    DOI： 10.1149/06917.0657ecst 　

    ISSN：1938-6737 1938-5862

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    The electrochemical structural stability of Au-modified Pt nanoparticles (Aux/Pt100 NPs, where x is the atomic ratio of Au) was investigated. Aux/Pt100 samples were fabricated on a highly oriented pyrolytic graphite substrate at 773 K through sequential arc plasma depositions of Pt followed by Au. In cyclic voltammograms of Aux/Pt100, characteristic currents correlated to the corner and edge sites of the Pt NPs (0.13 V vs. RHE) decreased with increasing x. Electrochemical surface area decay, observed after applying potential cycling between 0.6 and 1.0 V, clearly show that surface modification of the Pt NPs with appropriate amounts of Au atoms located at the corner and edge sites improved the structural stability of the Pt NPs.

  53. Effects of core-shell interface structures on ORR activities: A model catalyst study of Pt/Pd(111) 査読有り

    Naoto Todoroki, Yohe Bando, Hirofumi Watanabe, Toshimasa Wadayama

    ECS Transactions　69　(17)　315-320　2015年

    出版者・発行元：Electrochemical Society Inc.

    DOI： 10.1149/06917.0315ecst 　

    ISSN：1938-6737 1938-5862

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    We investigated surface structures and oxygen-reduction reactions (ORR) of Pt-Pd(111) model bimetallic surfaces fabricated by molecular beam epitaxy. The Pt/Pd(111) surfaces were prepared by depositing 0.6-nm-thick Pt on Pd(111) at substrate temperatures of 573 and 673 (xK-Pt0.6nm/Pd(111), where x = 573 or 673). Reflection high-energy electron diffraction patterns and ultra-highvacuum scanning tunneling microscopy images revealed that Pt grew epitaxially on the Pd(111) substrate under the deposition conditions selected for the study. However, analysis of low-energy ion scattering results suggested that the Pt and Pd atomic compositions of the topmost surfaces were different for 573KPt0.6nm/ Pd(111) and 673K-Pt0.6nm/Pd(111). The ORR activities of the 573K-Pt0.6nm/Pd(111) and 673K-Pt0.6nm/Pd(111) surfaces were 6.3 and 3.6 higher than that for Pt(111), respectively. The results indicate that alloy structures near the surface determine the ORR activity of practical Pd@Pt core-shell catalysts.

  54. Electrochemical Properties of Pt Epitaxial Layers Formed on Pd(111) in Ultra-High Vacuum 査読有り

    Y. Bando, Y. Takahashi, E. Ueta, N. Todoroki, T. Wadayama

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY　162　(4)　F463-F467　2015年

    出版者・発行元：ELECTROCHEMICAL SOC INC

    DOI： 10.1149/2.0951504jes 　

    ISSN：0013-4651

    eISSN：1945-7111

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    Electrocatalytic properties for oxygen reduction reaction (ORR) of Pt(111) epitaxial layers on a Pd(111) substrate are investigated. Scanning tunneling microscopy images of the as-prepared 0.6-nm- and 1.2-nm-thick Pt(111) epitaxial layers on Pd(111) (Pt-0.6nm/Pd(111) and Pt-1.2nm/Pd(111)) revealed that the topmost surface has atomically flat, 50-100-nm-wide terraces. Remarkable current features due to hydrogen storage and emission by the Pd(111) substrate dominated the cyclic voltammograms of Pt-0.6nm/Pd(111) in the potential range of 0.15-0.4 V vs. a reversible hydrogen electrode. In contrast, the curve of Pt-1.2nm/Pd(111) exhibited a shrinkage in the hydrogen charges (Q(H)) in the potential range of 0.25-0.4 V, accompanied by the emergence of symmetrical redox features at 15 mV on the positive potential side, relative to Pt(111) "butterfly" feature. Both Pt-0.6nm/Pd(111) and Pt-1.2nm/Pd(111) showed ca. four times higher ORR activity than clean Pt(111), although their hydrogen-related behaviors and activity changes during applying potential cycles were much different. The results suggest that shrinkage in QH and positive shift in the onset potential of hydroxyl species are common features of the CV of highly ORR-active well-defined Pt-M(111) bimetallic surfaces and that the activity enhancements and the structural stabilities fairly depend on the surface structure of the epitaxial Pt(111) lattice. (C) The Author(s) 2015. Published by ECS. All rights reserved.

  55. Oxygen reduction reaction activity and structural stability of Pt-Au nanoparticles prepared by arc-plasma deposition 査読有り

    Shuntaro Takahashi, Hiroshi Chiba, Takashi Kato, Shota Endo, Takehiro Hayashi, Naoto Todoroki, Toshimasa Wadayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS　17　(28)　18638-18644　2015年

    出版者・発行元：ROYAL SOC CHEMISTRY

    DOI： 10.1039/c5cp02048d 　

    ISSN：1463-9076

    eISSN：1463-9084

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    The oxygen reduction reaction (ORR) activity and durability of various Au-x/Pt-100 nanoparticles (where x is the atomic ratio of Au against Pt) are evaluated herein. The samples were fabricated on a highly-oriented pyrolytic graphite substrate at 773 K through sequential arc-plasma depositions of Pt and Au. The electrochemical hydrogen adsorption charges (electrochemical surface area), particularly the characteristic currents caused by the corner and edge sites of the Pt nanoparticles, decrease with increasing Au atomic ratio (x). In contrast, the specific ORR activities of the Au-x/Pt-100 samples were dependent on the atomic ratios of Pt and Au: the Au-28/Pt-100 sample showed the highest specific activity among all the investigated samples (x = 0-42). As for ORR durability evaluated by applying potential cycles between 0.6 and 1.0 V in oxygen-saturated 0.1 M HClO4, Au-28/Pt-100 was the most durable sample against the electrochemical potential cycles. The results clearly showed that the Au atoms located at coordinatively-unsaturated sites, e.g. at the corners or edges of the Pt nanoparticles, can improve the ORR durability by suppressing unsaturated-site-induced degradation of the Pt nanoparticles.

  56. Oxygen reduction reaction activities for various-monolayer-thick Pt shells on PtxNi100-x(111) 査読有り

    Masato Asano, Ryutaro Kawamura, Naoto Todoroki, Toshimasa Wadayama

    ECS Transactions　69　(17)　619-624　2015年

    出版者・発行元：Electrochemical Society Inc.

    DOI： 10.1149/06917.0619ecst 　

    ISSN：1938-6737 1938-5862

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    We studied the oxygen reduction reaction (ORR) activities for two monolayer (ML)-thick Pt on PtxNi100-x(111) (Pt2ML/PtxNi100-x(111)) model core-shell catalysts fabricated by molecular beam epitaxy (MBE). Low-energy electron diffraction patterns for all Pt2ML/PtxNi100-x(111) showed six-fold surface symmetry with longrange ordering, indicating a (111) atomic arrangement of the topmost Pt shell layers. Furthermore, scanning tunneling microscopy images of the Pt2ML/Pt50Ni50(111) and Pt2ML/Pt25Ni75(111) surfaces exhibited Moiré-like height modulations, which are likely induced by large lattice mismatches between the topmost Pt(111) shell layers and the Pt-Ni(111) substrates. The ORR activity of Pt2ML/PtxNi100-x(111) increased with the Ni composition the enhancement factors are 8-, 18-, and 25-fold vs. Pt(111) for Pt2ML/Pt75Ni25(111), Pt2ML/Pt50Ni50(111), and Pt2ML/Pt25Ni75(111), respectively. The results suggested that the Pt surface strains induced by lattice mismatches between the Pt shells and Pt-Ni substrates increased with the Ni composition, leading to a marked enhancement in ORR activity, particularly for Pt2ML/Pt25Ni75(111).

  57. Microscopic surface structures and ORR activities for vacuum-deposited Pt/Ni/Pt(111) and Pt/Ni/Pt(110) sandwich structures 査読有り

    N. Todoroki, T. Dasai, Y. Asakimori, T. Wadayama

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY　724　15-20　2014年6月

    出版者・発行元：ELSEVIER SCIENCE SA

    DOI： 10.1016/j.jelechem.2014.04.008 　

    ISSN：1572-6657

    eISSN：1873-2569

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    Pt0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 1) and Pt0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 0) atomic sandwich structures were prepared through alternating vacuum depositions of Ni followed by Pt onto clean Pt(1 1 1) and (1 1 0) substrates at room temperature under ultra-high-vacuum (UHV) conditions. After the samples were transferred from UHV to a 1-atm N-2 atmosphere, their oxygen reduction reaction (ORR) activities were evaluated in O-2-saturated 0.1 M HClO4 at 0.9V vs. reversible hydrogen electrode. Pt-0.6nm/Ni-0.6nm/Pt(1 1 1) and Pt-0.6nm/Ni-0.6nm/Pt(1 1 0) were most active among the respective Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich series: the activities of the former and latter sandwich structures were approximately five- and threefold greater than those of the corresponding clean Pt(1 1 1) and (1 1 0) substrate surfaces. Scanning tunneling microscopy images of the as-preparedPt(0.6nm)/Ni-0.6nm/Pt(1 1 1) and Pt-0.6nm/Ni-0.6nm/Pt(1 1 0) surfaces revealed three-dimensionally grown hexagonal-shaped small domains of Pt(1 1 1) (approximately 2 nm in size) and parallelogram-shape (1 1 0) terrace islands oriented along (1 1 0), respectively. The results indicate that not only the atomic arrangements of the topmost Pt layers but also the nanoscale morphologies of Pt-Ni in the surface vicinities determine the enhancement of the ORR activity of Pt-M alloy catalysts. (C) 2014 Elsevier B.V. All rights reserved.

  58. Oxygen Reduction Reaction Activities for Pt/Au(hkl) Bimetallic Surfaces Prepared by Molecular Beam Epitaxy 査読有り

    Yuki Iijima, Takayuki Kondo, Yu Takahashi, Yohe Bando, Naoto Todoroki, Toshimasa Wadayama

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY　160　(8)　F898-F904　2013年

    出版者・発行元：ELECTROCHEMICAL SOC INC

    DOI： 10.1149/2.011309jes 　

    ISSN：0013-4651

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    We investigated electrochemical properties for the Pt-Au bimetallic surfaces prepared by 0.3-nm-thick Pt depositions on Au(111), (110), and (100) substrates (Pt-0.3nm/Au(hkl)) by molecular beam epitaxy. The Pt-0.3nm/Au(111) surface prepared at the substrate temperature of 300 K (300K-Pt-0.3nm/Au(111)) showed a corrugated Pt(111) epitaxial surface on which 3-5 nm size monoatomic height Pt islands are located. Oxygen reduction reaction (ORR) activity of the surface was enhanced by a factor of ca. 2 relative to that of the clean Pt(111) surface. In contrast, the topmost surfaces of 473K-Pt-0.3nm/Au(111), 300K-Pt-0.3nm/Au(100), and 300K-Pt-0.3nm/Au(110) were composed of both Pt and Au atoms, and the ORR activities were lower than those for corresponding clean surfaces. The specific ORR activities for the Pt-0.3nm/Au(111) and Pt-0.3nm/Au(100) surfaces estimated after recording CV curves of 0.05-1.7 V were enhanced relative to the as-prepared samples, although the activity of the Pt-0.3nm/Au(110) surface was slightly decreased by the wide region CV recording. These results suggest that atomic arrangements of surface Pt atoms, particularly the most dense plane of Pt(111), determine the ORR activity enhancement for Pt-Au bimetallic surfaces. (C) 2013 The Electrochemical Society. All rights reserved.

  59. Oxygen reduction reaction activities for Pt-enriched Co/Pt(111), Co/Pt(100), and Co/Pt(110) model catalyst surfaces prepared by molecular beam epitaxy 査読有り

    Y. Yamada, K. Miyamoto, T. Hayashi, Y. Iijima, N. Todoroki, T. Wadayama

    SURFACE SCIENCE　607　54-60　2013年1月

    出版者・発行元：ELSEVIER SCIENCE BV

    DOI： 10.1016/j.susc.2012.08.016 　

    ISSN：0039-6028

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    Oxygen reduction reaction (ORR) activities for 0.3 nm thick Co deposited Pt(111), Pt(100), and Pt(110) surfaces prepared by molecular beam epitaxy (MBE) were investigated after the samples were transferred from ultra-high vacuum (UHV) to an electrochemical system without being exposed to air. The low-energy electron diffraction and IR reflection-absorption spectroscopic results for adsorbed carbon monoxide indicated that Co deposition on the low-index single-crystal Pt substrates at 753 K-773 K led to Pt-enrichment at the topmost surfaces through surface segregation of the substrate Pt atoms. The ORR activity was evaluated in O-2-saturated 0.1 M HClO4 at 0.9 V vs. reversible hydrogen electrode (RHE) for the as-prepared Pt-enriched Co-0.3 nm/Pt(111), Co-0.3 (nm)/(100), and Co-0.3 nm/(110) surfaces; the respective surfaces exhibited about 10, 2, and 1.5 times the ORR activity relative to their corresponding clean surfaces. When 1000 potential cycles between 0.6 V and 1.0 V were applied, the activities for the Pt-enriched Co-0.3 nm/Pt(111) and Co-0.3 nm/Pt(110) surfaces decreased and came close to that for as-cleaned Pt(110). These results show that the ORR activity enhancement for Pt-Co alloy surfaces significantly depends upon the atomic arrangement of the Pt-enriched topmost surfaces and the underlying Co atoms. (c) 2012 Elsevier B.V. All rights reserved.

  60. Effective shell layer thickness of platinum for oxygen reduction reaction alloy catalysts 査読有り

    Naoto Todoroki, Yu Asakimori, Toshimasa Wadayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS　15　(41)　17771-17774　2013年

    出版者・発行元：ROYAL SOC CHEMISTRY

    DOI： 10.1039/c3cp53340a 　

    ISSN：1463-9076

    eISSN：1463-9084

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    Effects of surface Pt monolayer thickness on electrochemical oxygen reduction reaction of molecular-beam-epitaxially-prepared Pt/Ni/Pt(111) were investigated. The effective thickness of Pt for stabilizing the topmost surface can be deduced to be three monolayers.

  61. Structure and electrochemical stability of Pt-enriched Ni/Pt(111) topmost surface prepared by molecular beam epitaxy 査読有り

    Naoto Todoroki, Yuki Iijima, Ryota Takahashi, Yu Asakimori, Toshimasa Wadayama

    Journal of the Electrochemical Society　160　(6)　F591-F596　2013年

    DOI： 10.1149/2.082306jes 　

    ISSN：0013-4651 1945-7111

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    We investigated the atomic-scale structure and electrochemical stability of a Pt-enriched topmost surface (Pt-enriched Ni/Pt(111)) prepared through monolayer Ni deposition on Pt(111) at 823 K using molecular beam epitaxy. Reflection high-energy electron diffraction patterns and an ultra-high vacuum scanning tunneling microscopic (UHV-STM) image of the Pt-enriched Ni/Pt(111) surface showed that the surface has long-range-ordered six-fold symmetry with atomic-scale corrugations. Although the oxygen reduction reaction (ORR) activity of the as-prepared Pt-enriched surface was eight times higher than that of clean Pt(111), the ORR activity degraded steeply during potential cycles between 0.6 and 1.0 V in O2-saturated 0.1 M HClO4. After 1000 potential cycles, the enhancement factor was estimated to be 2. An STM image collected after the potential cycles showed island-like structures (ca. 5-9 nm in diameter and 0.4-0.8 nm in height). Furthermore, the intensity of the Ni 2p core-level band for the as-prepared sample decreased after the 1000 potential cycles, revealing dissolution of the Ni atoms located at the subsurface layer. This experimental study clearly demonstrates that the underlying-Ni-induced specific surface strains and electronic state of the Pt-enriched topmost surface sorely contribute to the remarkable ORR activity of the Ni/Pt(111) surface. © 2013 The Electrochemical Society. All rights reserved.

  62. Platinum-enriched Ni/Pt(111) surfaces prepared by molecular beam epitaxy: Oxygen reduction reaction activity and stability 査読有り

    Naoto Todoroki, Ryota Takahashi, Yuki Iijima, Yoshinori Yamada, Takehiro Hayashi, Toshimasa Wadayama

    Materials Transactions　54　(9)　1735-1740　2013年

    DOI： 10.2320/matertrans.M2013061 　

    ISSN：1345-9678

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    Oxygen reduction reaction (ORR) activities and electrochemical stabilities were evaluated for Ni/Pt(111) model electrode-catalysts fabricated by molecular beam epitaxy (MBE). Exposure of clean Pt(111) to 1.0-Langmuir (i.e., fractional coverage, θ = 1.0 in the Langmuir isotherm) CO at 300K produced linear-bonded and bridge-bonded COPt IR bands at 2093 and 1858 cm-1. In contrast, 3.0-nm-thick Ni deposition onto Pt(111) at 823K (823 K-Ni 3.0nm/Pt(111)) showed broad IR bands for adsorbed CO at around 2064 cm-1 the separation of reflection high-energy electron diffraction (RHEED) streaks of the 823 K-Ni3.0nm/Pt(111) is greater than for clean Pt(111). In contrast, 923 KNi3.0nm/ Pt(111) yielded a single sharp IR band because of linear-bonded CO at 2080 cm-1, and the separation of the RHEED streaks is almost the same as that for the Pt(111). The results suggest that a Pt-enriched topmost surface is generated above 923K through surface segregation of the substrate Pt atoms during the Ni deposition. After transferring the sample from ultra-high vacuum to an electrochemical system, without being exposed to air, changes in ORR activities of the MBE-prepared 923 K-Ni3.0nm/Pt(111) were evaluated in a 0.1-mol L -1 HClO4 aqueous solution under applied potential cycles of between 0.6 and 1.0V vs. RHE. The ORR activity enhancement factor vs. clean Pt(111) for the asprepared 923 K-Ni3.0nm/Pt(111) was estimated to be twelve, and this factor was reduced to four after the application of 1000 potential cycles. However, a 943 K-Ni3.0nm/Pt(111) sample, which showed a relatively low ORR activity (an enhancement factor of eight), had the activity enhancement factor of six even after the application of 1000 potential cycles. These results reveal that the sub-surface structures and composition of Pt-based alloys determine not only initial ORR activity but also electrochemical durability of the ORR catalysts. © 2013 The Japan Institute of Light Metals.

  63. Oxygen reduction reaction activities of Pt/Au(111) surfaces prepared by molecular beam epitaxy 査読有り

    Yuki Iijima, Yu Takahashi, Ken-ichi Matsumoto, Takehiro Hayashi, Naoto Todoroki, Toshimasa Wadayama

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY　685　79-85　2012年10月

    出版者・発行元：ELSEVIER SCIENCE SA

    DOI： 10.1016/j.jelechem.2012.09.007 　

    ISSN：1572-6657

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    Pt-deposited Au(1 1 1) surfaces were prepared by molecular beam epitaxy (MBE). Surface structures of the samples were verified with reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM) and infrared reflection absorption spectroscopy (IRRAS) for adsorbed carbon monoxide in an ultra-high vacuum (UHV) condition. The UHV-results show that epitaxial growth of Pt(1 1 1) on clean Au(1 11). A 0.3-nm-thick Pt deposition found to almost cover the Au surface. In addition, mono-atomic-height Pt islands were observed on the topmost surface. Electrochemical properties were evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) using a rotating disk electrode apparatus set in an N-2-purged glove box. A CV curve of the Pt(0.3)n(m)/Au(1 1 1) recorded in the potential region of 0.05-1.0 V vs. reversible hydrogen electrode (RHE) was similar to that of clean Pt(1 1 1), except for the lack of 'butterfly' peaks at 0.8 V. Oxygen reduction reaction (ORR) activities of the samples were evaluated by kinetic controlled current densities at 0.9 V; the activity of the Pt-0.3nm/Au(1 1 1) was ca. 1.8 times higher than that of the clean Pt(1 1 1). During CV curve measurements of the Pt-0.3nm/Au(1 1 1) in the region of 0.05-1.7 V, a redox feature at 0.13 V became apparent; the ORR activity evaluated after the CV measurements was higher than the as-prepared sample. An UHV-STM image collected after re-transfer from the glove box showed two to three monoatomic-height Pt mounds whose slopes were 10-20 degrees. The results clearly showed that surface defects at the topmost Pt(1 1 1) layer such as steps contribute to the ORR enhancement of MBE-prepared Pt/Au(1 1 1). (C) 2012 Elsevier B.V. All rights reserved.

  64. ORR activity enhancement of MBE-prepared Pt monolayer on Au single-crystal substrate 査読有り

    Y. Iijima, Y. Takahashi, K. Matsumoto, N. Todoroki, T. Wadayama

    ECS Transactions　50　(36)　45-55　2012年

    DOI： 10.1149/05036.0045ecst 　

    ISSN：1938-5862 1938-6737

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    Oxygen reduction reaction (ORR) activities of Pt/Au(111) and Pt/Au(100) bimetallic surfaces prepared using molecular beam epitaxy were evaluated in this study. Surface structures of the bimetallic surfaces were verified using a scanning tunneling microscope under ultra-high vacuum conditions. The deposition of a 0.3-nm-thick Pt on a clean Au(111) at 300 K (300K-Pt0.3nm/ Au(111)) generated a corrugated Pt(111) epitaxial layer on which monoatomic-height Pt islands are present. The ORR activity estimated from the kinetically controlled current density at 0.9 V vs. RHE was ca. two times greater than that of the clean Pt(111). In contrast, the 473K-Pt 0.3nm/Au(111) as well as 300K-Pt0.3nm/Au(100) exhibited small hydrogen-related charges, thereby were less ORR active than the corresponding clean Pt substrate surfaces. These results suggest that atomic arrangements of surface Pt atoms, particularly the morphologies of the most dense plane of Pt(111), correlate with the enhancement in the ORR activity of Pt-u bimetallic nanoparticles. © The Electrochemical Society.

  65. Electrochemical stability of pt-enriched topmost surface of Ni/Pt(111) prepared by molecular beam epitaxy 査読有り

    N. Todoroki, Y. Iijima, R. Takahashi, Y. Yamada, K. Matsumoto, T. Hayashi, T. Wadayama

    ECS Transactions　50　(2)　1707-1713　2012年

    DOI： 10.1149/05002.1707ecst 　

    ISSN：1938-5862 1938-6737

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    Oxygen reduction reaction (ORR) activity and stability of a molecular beam epitaxially (MBE) prepared Pt-enriched Ni0.3nm/Pt(111) surface was investigated. Reflection high-energy electron diffraction (RHEED) patterns, and a scanning tunneling microscopic (STM) image indicated that the Pt-enriched surface has long-range-ordered six-fold symmetry with atomic-scale corrugations. ORR activity was estimated by kinetically-controlled current density at 0.9 V vs. a reversible hydrogen electrode, and the as-prepared Pt-enriched surface showed 8-times-higher ORR activity than clean Pt(111). The activity steeply reduced during potential cycling between 0.6 V and 1.0 V. After 1000 potential cycles, the enhancement factor was 2.5 and a cyclic voltammetry (CV) curve exhibited an increase in EC charge for the Haddes region accompanied by the emergence of a 0.13 V redox feature caused by (110) surface defects. These results suggest that the electrochemical stability of the underlying Ni atoms determines the durability of Pt-Ni alloy catalysts. © The Electrochemical Society.

  66. Outermost Surface Structures and Oxygen Reduction Reaction Activities of Co/Pt(111) Bimetallic Systems Fabricated Using Molecular Beam Epitaxy 査読有り

    Toshimasa Wadayama, Hirosato Yoshida, Koichiro Ogawa, Naoto Todoroki, Yoshinori Yamada, Kanji Miyamoto, Yuki Iijima, Tatsuya Sugawara, Kazuki Arihara, Seiho Sugawara, Kazuhiko Shinohara

    JOURNAL OF PHYSICAL CHEMISTRY C　115　(38)　18589-18596　2011年9月

    出版者・発行元：AMER CHEMICAL SOC

    DOI： 10.1021/jp203845u 　

    ISSN：1932-7447

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    We studied oxygen reduction reaction (ORR) activities for outermost surfaces of 0.3 nm thick Co deposited on Pt (111) (Co(0.3) (nm)/Pt(111)) bimetallic systems fabricated using molecular beam epitaxy at various Co deposition temperatures. Results show that Co(0.3) (nm)/Pt(111) fabricated at temperatures lower than 393 K displays extra low-energy electron diffraction (LEED) spots outside the integer ones, indicating incoherent epitaxial growth of Co. A new IR band that is attributed to linearly bonded carbon monoxide (CO) on the Pt site influenced by neighboring Co atoms emerges at 2052 cm(-1) for 333 K fabricated Co(0.3) (nm)/Pt(111), in addition to the CO-Pt and CO-Co bands. With increasing fabrication temperature, the new band shifts to higher frequencies and reaches 2082 cm(-1) for 773 K fabricated Co(0.3) (nm)/Pt(111), which has a diffuse (1 x 1) LEED pattern. We evaluated the dependence of the deposition temperature on the lattice parameters of the Co(0.3) (nm)/Pt(111) and ascribed the band at 2082 cm(-1) to adsorbed CO on a Pt-enriched topmost surface having 6-fold symmetry. Although the incoherent epitaxial Co layer was unstable in 0.1 MHClO(4) aqueous solution, the Pt-enriched topmost surface is rather stable and the ORR activity is 10 times higher than that for clean Pt(111). The activities for Pt(0.3 nm), (0.6 nm)/Co(0.3) nm/Pt(111) artificial sandwich (superlattice) surfaces were also evaluated. The obtained results indicate that the Co atoms located at the second atomic layer strongly modify the electrocatalysis of the topmost surface.

  67. Oxygen reduction reaction activities of Ni/Pt(111) model catalysts fabricated by molecular beam epitaxy 査読有り

    Toshimasa Wadayama, Naoto Todoroki, Yoshinori Yamada, Tatsuya Sugawara, Kanji Miyamoto, Yuki Iijama

    ELECTROCHEMISTRY COMMUNICATIONS　12　(8)　1112-1115　2010年8月

    出版者・発行元：ELSEVIER SCIENCE INC

    DOI： 10.1016/j.elecom.2010.05.042 　

    ISSN：1388-2481

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    Oxygen reduction reaction (ORR) activities were evaluated for clean Pt(111) and Ni/Pt(111) model catalysts fabricated by molecular beam epitaxy. Exposure of clean Pt(111) to 1.0 LCO at 303 K produced linear-bonded and bridge-bonded CO-Pt IR bands at 2093 and 1858 cm(-1). In contrast, 0.3-nm-thick Ni deposited on Pt(111) at 573 K (573 K-Ni(0.3 nm)/Pt(111)) produced broad IR bands for adsorbed CO at around 2070 cm(-1); the separation of reflection high-energy electron diffraction (RHEED) streaks is slightly wider for 573 K-Ni(0.3 nm)/Pt(111) than for the clean Pt(111). For 823 K-Ni(0.3 nm)/Pt(111), the separation of the RHEED streaks is the same as that for the Pt(111). and a single sharp IR band due to adsorbed CO is located at 2082 cm(-1). The results suggest that for the 823 K-Ni(0.3 nm)/Pt(111), a Pt-enriched outermost surface (Pt-skin) was formed through surface segregation of the substrate Pt atoms. ORR activities for the 573 K- and 823 K-Ni(0.3 nm)/Pt(111) as determined from linear sweep voltammetry curves were five times and eight times higher than that for clean Pt(111), respectively, demonstrating that Pt-skin generation is crucial for developing highly active electrode catalysts for fuel cells. (C) 2010 Elsevier B.V. All rights reserved.

  68. Carbon monoxide adsorption on Co deposited Pt(100)-hex: IRRAS and LEED investigations 査読有り

    T. Wadayama, H. Yoshida, K. Ogawa, N. Todoroki, Y. Yamada

    APPLIED SURFACE SCIENCE　256　(14)　4517-4521　2010年5月

    出版者・発行元：ELSEVIER SCIENCE BV

    DOI： 10.1016/j.apsusc.2010.02.039 　

    ISSN：0169-4332

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    Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on Pt(1 0 0) surfaces deposited with Co layers with different thicknesses. Pt(1 0 0) surfaces cleaned in ultrahigh vacuum showed surface reconstruction, i.e., Pt(1 0 0)-hex: two absorption bands ascribable to adsorbed CO on the 1x1 surface and hex domains emerge at 2086 and 2074cm-1, respectively, after 1.0 L CO exposure. Deposition of a 0.3-nm-thick-Co layer on Pt(1 0 0)-hex at 333K changes the low-energy electron diffraction (LEED) pattern from hex to p(1x1), indicating that the deposited Co lifts the reconstruction. The IRRAS spectrum for 1.0-L-CO-exposed Co0.3nm/Pt(1 0 0)-hex fabricated at 333K yields a single absorption band at 2059cm(-1). For Co0.3nm/Pt(1 0 0)-hex fabricated at 693 K, the LEED pattern shows a less-contrasted hex and the pattern remains nearly unchanged even after CO exposure of 11 L, although only 1.0 L CO exposure to Pt(1 0 0)-hex lifts the surface reconstruction. A Co0.3nm/Pt(1 0 0)hex surface fabricated at 753K exhibits an absorption band at 2077cm(-1), which is considered to originate from CO adsorbed on the Pt-enriched surface alloy. Co0.3nm/Pt(1 0 0)-hex surfaces fabricated above 773K show a clear hex-reconstructed LEED pattern, and the frequencies of the adsorbed CO bands are comparable to those of Pt(1 0 0)-hex, indicating that the deposited Co atoms are diffused near the surface region. The outermost surface of the 3.0-nm-thick-Co-deposited Pt(1 0 0)-hex is composed of Pt-Co alloy domains even at a deposition temperature of 873 K. Based on the LEED and IRRAS results, the outermost surface structures of Cox/Pt(1 0 0)-hex are discussed. (C) 2010 Elsevier B. V. All rights reserved.

  69. Carbon monoxide adsorption on cobalt-deposited platinum single crystal surfaces investigated by IR reflection-absorption and low-energy electron diffraction 査読有り

    Hirosato Yoshida, Koichiro Ogawa, Naoto Todoroki, Yoshinobu Yamada, Toshimasa Wadayama

    e-Journal of Surface Science and Nanotechnology　8　161-166　2010年4月17日

    DOI： 10.1380/ejssnt.2010.161 　

    ISSN：1348-0391

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    Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on Co deposited Pt(111) (Co/Pt(111)) and Pt(100) (Co/Pt(100)) (Co thickness = 0.15, 0.3 and 0.6 nm) bimetallic surfaces. The 1.0-L-CO exposure to a clean Pt(111) at room temperature yielded linear-bonded and bridgebonded CO-Pt bands at 2092 and 1850 cm-1. The Co depositions onto the Pt(111) at 333 K brought about the small hexagons of satellites on the low-energy electron diffraction (LEED) patterns, even for the Co thickness of 0.15 nm. The CO-Pt IRRAS band intensities for the 333-K-fabricated Co/Pt(111) surfaces decreased with increasing Co thickness. The CO-Pt bands almost disappeared for the 6nm-thick-Co/Pt(111) surface and the band at 2000 cm-1 that ascribable to CO-Co bonds dominated the spectra. The results indicated that the deposited Co grows epitaxially on the 333-K-Pt(111) substrate. In contrast, the 693-K-fabricated 0.3nm-thick-Co/ Pt(111) which showed a clear p(1×1) LEED pattern yielded a single absorption band at 2067 cm-1 originated from adsorbed CO on the Pt site influenced by neighbored Co atoms. As for the cleaned Pt(100) substrate surface, the LEED pattern showed a hex-reconstructed pattern and the 1.0-L-CO exposed surface arose two absorption bands at 2086 and 2076 cm-1, which can be ascribed respectively to linearly bonded CO on Pt in the 1×1 and hex domains. The Co depositions onto the 333-K-Pt(100)-hex substrate surface lift the hex reconstruction. The adsorbed CO on the 333-K-fabricated 0.3nm-thick-Co/Pt(100)-hex revealed a single absorption band at 2059 cm -1. In contrast to the 333-K-fabricated surface, the 693-K-fabricated 0.3nm-thick-Co/Pt(100)-hex showed the hex-like reconstruction: the 1.0-L-CO exposure to the 693-K-fabricated surface resulted in an adsorbed CO band at 2073 cm-1 accompanied with a shoulder at 2059 cm-1. The results obtained suggest that the deposited Co atoms are easy to incorporated into the Pt(100)-hex substrate surface in comparison to the Pt(111). © 2010 The Surface Science Society of Japan.

  70. Infrared reflection absorption spectral study for CO adsorption on Pd/Pt(111) bimetallic surfaces 査読有り

    N. Todoroki, H. Osano, T. Maeyama, H. Yoshida, T. Wadayama

    APPLIED SURFACE SCIENCE　256　(4)　943-947　2009年11月

    出版者・発行元：ELSEVIER SCIENCE BV

    DOI： 10.1016/j.apsusc.2009.05.070 　

    ISSN：0169-4332

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    Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on 0.15 nm-thick-0.6 nm-thick Pd-deposited Pt(1 1 1) bimetallic surfaces: Pd(x)/Pt(1 1 1) (where x is the Pd thickness in nanometers) fabricated using molecular beam epitaxial method at substrate temperatures of 343 K, 473 K, and 673 K. Reflection high-energy electron diffraction (RHEED) measurements for Pd(0.15-0.6) (nm)/Pt(1 1 1) surfaces fabricated at 343 K showed that Pd grows epitaxially on a clean Pt(1 1 1), having an almost identical lattice constant of Pt(1 1 1). The 1.0 L CO exposure to the clean Pt(1 1 1) at room temperature yielded linearly bonded and bridge-bonded CO-Pt bands at 2093 and 1855 cm (1). The CO-Pt band intensities for the CO-exposed Pd(x)/Pt(1 1 1) surfaces decreased with increasing Pd thickness. For Pd(0.3nm)/Pt(1 1 1) deposited at 343 K, the 1933 cm (1) band caused by bridge-bonded CO-Pd enhanced the spectral intensity. The linear-bonded CO-Pt band (2090 cm (1)) almost disappeared and the bridge-bonded CO-Pd band dominated the spectra for Pd(0.6nm)/Pt(1 1 1). With increasing substrate temperature during the Pd depositions, the relative band intensities of the CO-Pt/CO-Pd increased. For the Pd(0.3nm)/Pt(1 1 1) deposited at 673 K, the linear-bonded CO-Pt and bridge-bonded CO-Pd bands are located respectively at 2071 and 1928 cm (1). The temperature-programmed desorption (TPD) spectrumfor the 673 K-deposited Pd(0.3nm)/Pt(1 1 1) showed that a desorption signal for the adsorbed CO on the Pt sites decreased in intensity and shifted ca. 20 K to a lower temperature than those for the clean Pt(1 1 1). We discuss the CO adsorption behavior on well-defined Pd-deposited Pt(1 1 1) bimetallic surfaces. (C) 2009 Elsevier B.V. All rights reserved.

  71. Carbon monoxide adsorption on Ni/Pt(111) surfaces investigated by infrared reflection absorption spectroscopy 査読有り

    Toshimasa Wadayama, Hirosato Yoshida, Naoto Todoroki, Shogo Oda

    e-Journal of Surface Science and Nanotechnology　7　230-233　2009年4月4日

    DOI： 10.1380/ejssnt.2009.230 　

    ISSN：1348-0391

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    Infrared reflection absorption spectroscopic (IRRAS) measurements were conducted for carbon monoxide (CO) adsorption on Pt(111) bimetallic surfaces with various thicknesses of deposited Ni, i.e., Nix/Pt(111) (x, Ni thickness in nanometer units), which were fabricated using molecular beam epitaxy at substrate temperatures of 343-473 K. The reflection high-energy electron diffraction (RHEED) patterns for the 343-K-deposited Ni 0:1nm-0:6nm /Pt(111) reveal Ni epitaxial growth on Pt(111). The CO exposure to the clean Pt(111) surface at 323 K engenders linearly bonded and bridge-bonded CO-Pt bands at 2093 and 1858 cm-1. The 343-K-deposited Ni0:1nm /Pt(111) gives rise to a new band at 2070 cm-1 in addition to the CO-Pt(111) bands. T he new band is most prominent for the Ni0:3nm /Pt(111), on which the bridge-bonded CO on the Ni admetal layer appears at 1874 cm-1. For the Ni0:6nm /Pt(111), the 2070 cm-1 band decreases in intensity and the bridge-bonded CO on the Ni admetal-layerdominates the spectrum, with accompanying weak absorption at 2035 cm-1 caused by linearly adsorbed CO on the Ni layer. The low-energy electron diffraction (LEED) pattern for the 343-K-deposited Ni 0:3nm /Pt(111) shows incommensurate higher-order extra spots surrounding integer spots. In contrast, the incommensurate pattern changes to its original six-fold symmetry for the 473-K-deposited Ni0:3nm /Pt(111). In contrast, the RHEED pattern for the 473-K-deposited Ni 0:3nm /Pt(111) revealed streaks having slightly wider separations than those for the clean Pt(111). The IRRAS spectrum for the 1.0-L-CO exposed 473-K-deposited Ni0:3nm /Pt(111) reveals single-absorption at 2074 cm-1. We discuss the CO adsorption behavior of Nix/Pt(111) . © 2009 The Surface Science Society of Japan.

  72. IRRAS and TPD investigations of carbon monoxide adsorption on MBE grown Fe on Pt(100) 査読有り

    Toshimasa Wadayama, Hirosato Yoshida, Naoto Todoroki, Shogo Oda

    e-Journal of Surface Science and Nanotechnology　7　245-248　2009年4月4日

    DOI： 10.1380/ejssnt.2009.245 　

    ISSN：1348-0391

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    Infrared reflection absorption spectroscopy (IRRAS) and temperature programmed desorption (TPD) were used to investigate carbon monoxide (CO) adsorption on 0.25-1.0 monolayer (ML)-thick Fe deposited Pt(100) (Fe ∞(∞=0:25-1:0ML)/Pt(100)). The cleaned Pt(100) surface shows 5×20 reconstruction (Pt(100)-hex). The 1.0-LCO exposure to the Pt(100)-hex at 300 K yields linearly bonded CO-Pt bands at 2089 and 2081 cm -1. They are ascribable respectively to adsorbed CO on 1×1 and hex domains. Low-energy electron diffraction (LEED) patterns for the 343-K-deposited Fe∞/Pt(100) change from blurred hex (0.25 ML) to 1×1 (&gt 0.5 ML), indicating that the outermost surface structures changed through Fe thickness. Regarding the Fe0:25ML/Pt(100), two bands are located at 2082 and 2069 cm-1 for the 1.0-L-CO exposed surface. The Fe0:5ML/Pt(100), however, reveals a single absorption band at 2050 cm-1. The CO exposure to the Fe1:0ML/Pt(100) generates a broad and more red-shifted band at 2027 cm-1. In contrast, the LEED pattern for Fe0:5ML/Pt(100) fabricated at 873 K shows hex reconstruction. The IRRAS spectrum recorded after 1.0-L-CO exposure for the 873 K deposited Fe0:5ML/Pt(100) shows an absorption band at 2073 cm-1 with narrow bandwidth. The CO desorption temperature for the Pt(100)-hex (about 520 K) was shifted to a lower temperature by Fe deposition: the temperatures are about 470 and 430 K for the Fe 0:5ML/Pt(100) fabricated substrate temperatures of 343 and 873 K. Based on IRRAS and TPD results, CO adsorption behavior on the Fex/Pt(100) is discussed. © 2009 The Surface Science Society of Japan.

  73. Infrared Reflection Absorption Study for Carbon Monoxide Adsorption on Chromium Deposited Cu(100) Surfaces 査読有り

    T. Wadayama, H. Yoshida, S. Oda, N. Todoroki

    MATERIALS TRANSACTIONS　50　(4)　819-824　2009年4月

    出版者・発行元：JAPAN INST METALS

    DOI： 10.2320/matertrans.MRA2008442 　

    ISSN：1345-9678

    eISSN：1347-5320

    詳細を見る 詳細を閉じる

    This study investigates carbon monoxide (CO) adsorption and desorption behaviors on 0.1-0.6-mm-thick Cr-deposited Cu(100) surfaces using infrared reflection absorption (IRRAS) and temperature-programmed desorption (TPD) spectroscopic methods. Tire low-energy electron diffraction (LEED) pattern for the 0.1-nm-thick Cr-deposited Cu(100) surface indicates that distorted bcc-Cr(110) grows on fcc-Cu(100). The CO exposure to a clean Cu( 100) at 90 K produces a single and Sharp IR absorption hand at 2090cm(-1) that is attributable to adsorbed CO on the on-top site of the Cu atoms' on the surface. Two absorption bands are located at 2085 and 2105cm(-1) on the IRRAS spectrum for the CO-saturated 0.1-mm-thick Cr/Cu(110) surface. The former might originate from linearly hooded CO on the uncovered Cu substrate surface. with increasing Cr thickness, the latter high-frequency hand becomes prominent. For the 0.3-nm-thick Cr surface, the band at 21 17 cm(-1) dominates all spectra through CO exposure. The TPD spectra of the Cr-deposited Cu surfaces show two remarkable features at 220-250 and 320-390 K. which are ascribable respectively to Cu-CO and Cr-CO bonds, Lower desorption Peaks shift to higher temperatures with increasing Cr thickness. Based on TPD and IRRAS results. adsorption-desorption behaviors of CO on the Cr-deposited Cu(100) surfaces are discussed herein. [doi: 10.2320/matertrans.MRA2008442]

  74. Infrared reflection-absorption study of carbon monoxide adsorption on Fe/Pt(111) bimetallic surfaces 査読有り

    Toshimasa Wadayama, Hiroshi Osano, Toshiaki Maeyama, Hirosato Yoshida, Koji Murakami, Naoki Todoroki, Shogo Oda

    JOURNAL OF PHYSICAL CHEMISTRY C　112　(24)　8944-8950　2008年6月

    出版者・発行元：AMER CHEMICAL SOC

    DOI： 10.1021/jp712095w 　

    ISSN：1932-7447

    詳細を見る 詳細を閉じる

    Infrared reflection-absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on sub-monolayer (ML)-thick to 1.0 ML-thick Fe deposited Pt(111) bimetallic surfaces, that is, Fe-x/Pt(111) (x, Fe thickness in ML units), fabricated using molecular beam epitaxy at substrate temperatures of 343, 403, and 473 K. The 1.0 L CO exposure to a clean Pt(111) at room temperature yielded linearly bonded and bridge-bonded CO-Pt bands at 2093 and 1855 cm(-1). The CO-Pt band intensities for the CO-exposed surfaces of the Fex/Pt(111) decreased with increasing Fe thickness. The CO-Pt bands almost disappeared, and the bridge-bonded CO-Fe band at 1950 cm(-1) dominated the spectra for the Fe-1.0ML/Pt(111) deposited at 343 K. In addition, the Fe deposition brought about a new absorption band at around 2060 cm(-1); this band is predominant for the Fe-0.5ML/Pt(111) deposited at 473 K. The 1 ML-thick Fe deposition onto the 47 3 K Pt(111) engenders less-intense, rather broad absorption at 2050 cm-1, accompanied by a weak band attributable to bridge adsorption of CO on the surface Fe atoms. The IRRAS spectra for CO adsorption on the 0.6 nm and 0.3 nm-thick Pt grown on the Fe-1.0ML/Pt(111), that is, Pt-y/Fe-1.0ML/Pt(111) (y, Pt thickness in nm units), respectively, showed single absorption bands at 2080 and 2070 cm(-1). The reflection high-energy electron diffraction (RHEED) patterns for the Fe (1.0ML)/Pt(111) deposited at 343 K gave rise to new RHEED streaks, outside the original streaks, attributable to the substrate Pt(111). In contrast, for Pt-y/Fe-1.0ML/Pt(111) "sandwich" structures, the new streaks disappeared, leaving streaks that had slightly wider separation than that of the clean Pt(111). The Fe-0.5ML/Pt(111) deposited at 473 K showed similar streaks to those of the Pt/Fe-1.0ML/ Pt(111). The temperature-programmed desorption (TPD) spectrum of adsorbed CO on the Fe-0.5ML/Pt(111) deposited at 473 K revealed a 40% weaker and 10 K lower desorption signal than those for the clean Pt(111). We discuss the CO adsorption behavior on the well-defined Fe deposited Pt(111) bimetallic surfaces.

  75. Carbon monoxide adsorption on Pd-deposited Cu(110) surface: Infrared reflection absorption and temperature programmed desorption studies 査読有り

    T. Wadayama, H. Osano, H. Yoshida, S. Oda, N. Todoroki

    APPLIED SURFACE SCIENCE　254　(17)　5380-5384　2008年6月

    出版者・発行元：ELSEVIER SCIENCE BV

    DOI： 10.1016/j.apsusc.2008.02.061 　

    ISSN：0169-4332

    詳細を見る 詳細を閉じる

    We investigated carbon monoxide (CO) adsorption and desorption behaviors on 0.1-nm-, 0.15-nm-, and 0.3-nm-thick-Pd-deposited Cu( 1 1 0) surfaces using infrared reflection absorption (IRRAS) and temperature-programmed desorption (TPD) spectroscopic methods. CO was exposed to the 0.1-nm-thick-Pd/Cu( 1 1 0) surface at the substrate temperature of 90 K. The IR band attributable to CO bonded to Cu atoms emerged at 2092 cm (1): the band was located at 2100 cm (1) at saturation coverage, with a shoulder at 2110 cm (1). In addition to these bands, weak absorptions attributable to the Pd-CO bonds appeared at 2050 and 1960 cm (1). With increasing Pd thickness, the Pd related-bands became increasingly prominent. Particularly at the early stage of exposure, the band at 2115 cm (1) became visible. The band at 2117 cm (1) dominated the spectra all through the exposures for the 0.3-nm-thick-Pd surface. The TPD spectra of the surfaces showed two remarkable features at around 220-250 and 320-390 K, ascribable, respectively, to Cu-CO and Pd-CO. The desorption peaks shifted to higher temperatures with increasing Pd thickness. Based on the TPD and IRRAS results, we discuss the adsorption-desorption behaviors of CO on the Pd/Cu( 1 1 0) surfaces. (c) 2008 Elsevier B.V. All rights reserved.

︎全件表示 ︎最初の5件までを表示

MISC 11

  1. グリーン水素製造のための電極触媒研究

    轟直人, 和田山智正

    環境科学研究科ニュースレター　(25)　4-5　2024年3月

  2. アルカリ水電解用酸素発生電極への応用に向けた ステンレス鋼上への水酸化物ナノ構造触媒の生成 招待有り

    轟直人

    日本化学会研究会 「低次元系光機能材料研究会」 ニュースレター　(28)　11-12　2023年7月

  3. ステンレス鋼上へのナノ構造触媒層の形成とアルカリ水電解用酸素発生電極への応用 招待有り

    轟 直人

    まてりあ　62　(6)　368-374　2023年6月1日

    出版者・発行元：Japan Institute of Metals

    DOI： 10.2320/materia.62.368 　

    ISSN：1340-2625

    eISSN：1884-5843

  4. アークプラズム法でHOPG上に作成したPtAuナノ粒子の異常なAu-Au結合短縮について

    朝倉清高, HU Bing, 轟直人, 和田山智正, 東晃太朗, 宇留賀朋哉, 宇留賀朋哉, 岩澤康裕, 三輪(有賀)寛子, 高草木達

    触媒討論会講演予稿集(CD-ROM)　129th　2022年

    ISSN：2187-5928

  5. 水電解水素製造装置の高効率化に向けたステンレス鋼電極の開発 招待有り

    轟直人

    金属　92　(1)　51-59　2022年1月

  6. ドライプロセス法による表面原子構造制御に立脚した燃料電池電極触媒の開発 招待有り

    燃料電池　1　(20)　50-56　2020年7月

  7. よく規定された合金系電極触媒表面モデルのドライプロセス合成と特性評価 招待有り

    轟 直人, 和田山智正

    電気化学　87　(Autumn)　250-257　2019年8月

  8. 表面科学的視点に基づくエネルギー・物質変換触媒の開発 招待有り

    轟 直人

    まてりあ　58　(6)　328-332　2019年6月

  9. 東北大学環境材料表面科学研究室－電極触媒モデルのドライプロセス合成と評価－ 招待有り

    轟 直人, 和田山 智正

    燃料電池　18　82-86　2019年2月

  10. 光電子・共鳴Auger電子回折によるPt/Ni/Pt(111)表面の原子構造解析

    太田紘志, 轟直人, 和田山智正, 松井文彦

    日本物理学会講演概要集(CD-ROM)　72　(1)　2017年

    ISSN：2189-079X

  11. 超高真空中で作製したPt基合金モデル単結晶触媒の酸素還元反応活性 招待有り

    轟直人, 和田山智正

    Electrochemistry　83　(2)　101-105　2015年2月

    出版者・発行元：The Electrochemical Society of Japan

    DOI： 10.5796/electrochemistry.83.101 　

    ISSN：1344-3542

︎全件表示 ︎最初の5件までを表示

書籍等出版物 1

  1. グリーン水素製造に向けた水電解および周辺技術

    小島 宏一, 長澤 兼作, 轟 直人, 伊藤 良一, 松井 敏明, 中島 良

    情報機構　2023年10月

    ISBN: 9784865022582

講演・口頭発表等 53

  1. 表面・界面構造制御による水電解触媒の高機能化 招待有り

    轟直人

    日本分析化学会中国四国支部・宇部地区講演会　2024年2月7日

  2. グリーン水素製造のための触媒材料開発 招待有り

    轟直人

    第18回再生可能エネルギー世界展示会＆フォーラム　2024年1月25日

  3. 水電解装置用電極触媒の開発動向とステンレス鋼の応用可能性 招待有り

    轟直人

    技術情報協会セミナー、アニオン交換膜（AEM）型水電解技術の 展望と材料設計　2024年4月16日

  4. 電極触媒の表面・界面構造設計 招待有り

    轟直人

    HESS 第172回定例研究会　2024年2月21日

  5. 表面・界面構造制御による 電解電極触媒の高機能化 招待有り

    轟直人

    九州大学先導物質化学研究所内セミナー　2024年1月19日

  6. 水電解電極の表面界面構造制御（工業電解奨励賞 受賞講演） 招待有り

    轟直人

    第47回電解技術討論会 -ソーダ工業技術討論会-　2023年11月21日

  7. Enhanced Oxygen Evolution Activity and Stability of RuO2(110) Surface by Ti Doping

    Naoto Todoroki, Naomi Naraki, Toshimasa Wadayama

    244th ECS meeting　2023年10月8日

  8. RuO2/MO2/TiO2(110)(M=Sn, Ir)積層構造の酸素発生反応活性

    轟 直人, 工藤 龍太郎, 林 謙汰, 横井 瑞穂, 和田山 智正

    第46回電解技術討論会 -ソーダ工業技術討論会-　2022年11月17日

  9. Oxygen Evolution Activity of RuO2/MO2/TiO2(110) (M = Ir, Sn) Surfaces in Acidic Electrolyte

    Naoto Todoroki, Ryutaro Kudo, Kenta Hayashi, Mizuho Yokoi, Toshimasa Wadayama

    242nd ECS meeting　2022年10月9日

  10. ナノ構造触媒層を形成したステンレス鋼電極の水電解酸素発生特性（村上奨励賞受賞講演）

    轟 直人

    日本金属学会2022年秋季講演大会　2022年9月22日

  11. ステンレス鋼電極の水電解酸素発生特性に及ぼす鋼種の影響

    轟 直人, 四之宮 新, 和田山 智正

    第45回電解技術討論会 -ソーダ工業技術討論会-　2021年12月10日

  12. 単結晶薄膜電極を用いた高機能電極触媒表面構造の探索 招待有り

    轟直人

    2021年電気化学会東海支部-東北支部合同シンポジウム　2021年11月23日

  13. Electrochemical Stability of Stainless Steels-Made Alkaline Water Electrolysis Anodes Under Potential Cycle Loadings

    Naoto Todoroki, Shinomiya Arata, Toshimasa Wadayama

    240th ECS meeting

  14. 水電解電極への応用に向けたステンレス鋼上へのナノ構造触媒の構築 招待有り

    轟直人

    ナノ学会第19回大会　2021年5月21日

  15. 気相法により作製したIrO2/TiO2(110)表面系の酸素発生反応特性

    轟 直人, 林 謙汰, 横井 瑞穂, 和田山智正

    電気化学会第88回大会　2021年3月22日

  16. TiO2(110)基板上にアークプラズマ堆積したIrO2の酸素発生特性

    林 謙汰, 横井 瑞穂, 轟 直人, 和田山智正

    日本金属学会 第168回講演大会　2021年3月16日

  17. Electrochemical CO2 reduction on single crystal metal and alloy model catalysts 招待有り

    Naoto Todoroki, Hiroki Tei, Hiroto Tsurumaki, Taku Miyakawa, Toshimasa Wadayama

    日本化学会東北支部 化学系学協会東北大会　2020年9月27日

  18. Ni-Fe Hydroxide/Oxide Nanostructures generated on Stainless Steels for Efficient Alkaline Water Electrolysis

    Naoto Todoroki, Toshimasa Wadayama

    71st Annual Meeting of the International Society of Electrochemistry　2020年8月31日

  19. NiFe水酸化物皮膜を形成したステンレス鋼酸素発生電極の電気化学的耐久性

    轟 直人, 和田山 智正

    第43回電解技術討論会－ソーダ工業技術討論会－　2019年11月19日

  20. ステンレス鋼のアルカリ水電解電極への応用に向けた基礎検討

    轟直人, 和田山智正

    日本鉄鋼協会第178回秋季講演大会　2019年9月12日

  21. Oxygen Reduction Reaction Activity of Pt/Zr/Pt(111) model catalysts

    ECSJ Fall Meeting 2019　2019年9月6日

  22. Au基単結晶電極表面上における二酸化炭素電解還元反応

    轟 直人, 程 宏輝, 宮川 拓, 鶴巻 碩人, 和田山 智正

    2019年秋季電気化学会　2019年9月5日

  23. アルカリ水電解酸素発生電極としてのステンレス鋼の検討

    轟 直人, 和田山 智正

    電気化学会第86回大会　2019年3月29日

  24. ステンレス表面酸化皮膜のナノ構造と酸素発生特性

    轟 直人, 和田山 智正

    第42回電解技術討論会-ソーダ工業技術討論会-　2018年11月22日

  25. Oxygen Reduction and Oxygen Evolution Reaction Activity on Co/Pt(111) Surfaces in Alkaline Solution

    N. Todoroki, T. Wadayama

    AiMES2018　2018年9月30日

  26. モデルコアシェル単結晶触媒のドライプロセス構築と燃料電池電極触媒特性 招待有り

    轟 直人, 渡邊裕文, 金子聡真, 細田雅嗣, 番土陽平, 高橋俊太郎, 和田山智正

    第122回触媒討論会　2018年9月26日

  27. 物理構築モデル表面系を用いた燃料電池用Pt基触媒の材料設計 招待有り

    轟 直人

    日本金属学会2018年秋期講演大会　2018年9月21日

  28. Online Electrochemical Mass Spectrometry Study for CO2 Reduction on Co- and Sn-Deposited Au Single Crystal Surfaces

    N. Todoroki, H. Tei, H. Tsurumaki, T. Miyakawa, T. Mochizuki, T. Wadayama

    69th ISE Meeting　2018年9月3日

  29. ドライプロセスにより構築した単結晶コアシェルモデル触媒の酸素還元反応特性 招待有り

    轟 直人

    第25回燃料電池シンポジウム　2018年5月17日

  30. Au電極上におけるCO2還元生成物のオンライン質量分析

    轟 直人, 程 宏輝, 鶴巻 碩人, 望月 智裕, 宮川 拓, 和田山 智正

    第85回電気化学会　2018年3月10日

  31. 超高真空中で作製したPt基モデル単結晶合金・コアシェル触媒を用いたORR触媒設計指針構築 招待有り

    轟 直人

    第10回新電極触媒シンポジウム&宿泊セミナー　2017年10月28日

  32. 単結晶モデル触媒を用いた燃料電池電極触媒材料設計指針の構築 招待有り

    轟 直人

    電気化学会第30回東北若手の会　2017年10月28日

  33. Electrocatalytic Oxygen Reduction Reaction of Epitaxial Pt-Monolayers on Metal Single Crystal Substrates

    轟 直人

    ISSS-8　2017年10月24日

  34. アークプラズマ蒸着法により合成したPt基合金ナノ粒子の燃料電池電極触媒特性

    轟 直人, 高橋 俊太郎, 川口 浩太朗, 和田山 智正

    日本金属学会 2017年秋期講演大会　2017年9月7日

  35. Oxygen Reduction Reaction Activity for Vacuum-Deposited Pt-Monolayers on Metal Single Crystal Substrates

    轟 直人

    68th Annual Meeting of the International Society of Electrochemistry　2017年8月30日

  36. 貴金属単結晶基板上に形成したPt単原子層表面の酸素還元反応活性

    轟 直人, 渡邊 裕文, 金子 聡真, 細田 雅嗣, 番土 陽平, 和田山 智正

    第84回電気化学会　2017年3月27日

  37. 80℃電位サイクル負荷環境におけるPt/M(111)モデルコア－シェル系の酸素還元反応活性

    轟 直人, 谷 佑樹, 渡邊 裕文, 金子 聡真, 和田山 智正

    第57回電池討論会　2016年11月29日

  38. Surface Structures and Electrochemical Stabilities for Pt/Pd(111) Model Electrocatalysts

    轟 直人

    PRiME2016　2016年10月4日

  39. 二次元光電子回折法によるNi/Pt(111)モデル触媒表面の原子配列解析

    轟 直人, 松井 文彦, 太田 紘志, 和田山 智正

    3D活性サイト科学 第四回成果報告会　2016年9月10日

  40. Surface structures and electrocatalytic properties for well-defined Pt/Pd(111) surfaces

    轟 直人

    IVC-20　2016年8月22日

  41. Pt/Pd(111)モデル触媒の最表面構造と電気化学的安定性

    轟 直人, 番土 陽平, 谷 佑樹, 渡邊 裕文, 金子 聡真, 和田山 智正

    第83回電気化学会　2016年3月29日

  42. 光電子ホログラフィー法による白金基合金触媒の酸素還元反応を活性化する構成元素原子配列の解明

    轟 直人, 浅野 真仁, 高橋 俊太郎, 和田山 智正

    3D活性サイト科学 第三回成果報告会　2016年3月8日

  43. 固体高分子形燃料電池カソード用白金基合金触媒の原子レベル構造設計 招待有り

    轟 直人, 和田山 智正

    第379回電池技術委員会　2015年12月18日

  44. Pt/PtxNi1-x(111)系の最表面構造と酸素還元反応活性

    轟 直人, 川村 隆太郎, 浅野 真仁, 和田山 智正

    第56回電池討論会　2015年11月11日

  45. Oxygen reduction reaction activities for Pt-based single crystal alloy catalysts prepared by molecular beam epitaxy 招待有り

    轟 直人

    Internatioal Meeting of Fuel Cell Electrocatalysts　2015年11月10日

  46. Effects of Core-Shell Interface Structures on ORR Activities: a Model Catalyst Study of Pt/Pd(111)

    轟 直人

    228th ECS Meeting　2015年10月13日

  47. Pt基合金モデル単結晶の酸素還元反応活性に及ぼすPtシェル層厚の影響

    轟 直人, 川村 隆太郎, 番土 陽平, 浅野 真仁, 渡邊 裕文, 和田山 智正

    第82回電気化学会　2015年3月15日

  48. 規則相を有するPt基合金単結晶の酸素還元反応活性

    轟 直人, 川村 隆太郎, 浅野 真仁, 和田山 智正, “規則相を有する, 基合金単結晶の酸素還元反応活性

    第55回電池討論会　2014年11月21日

  49. ORR activity for Pt-Ni nanoparticles on HOPG prepared by arc plasma deposition

    轟 直人

    226th ECS Meeting　2014年10月8日

  50. Oxygen reduction activity of Pt-based alloy model catalysts prepared by molecular beam epitaxy

    轟 直人

    IUMRS-ICEM 2014　2014年6月11日

  51. Oxygen reduction activity of Pt-based alloy model catalysts prepared by molecular beam epitaxy 国際会議

    International Union of Materials Research Societies International Conference on Electronic Materials 2014　2014年6月10日

  52. 白金基合金モデル触媒のドライプロセス合成と燃料電池電極触媒特性 招待有り

    轟 直人

    触媒材料研究会 ミニシンポジウム「ナノ組織制御触媒の新展開」　2014年2月12日

  53. Oxygen Reduction Reaction Activities for Well-defined Pt-based Bimetallic Surfaces Prepared by Molecular Beam Epitaxy 招待有り

    轟 直人

    Local meeting for developments of fuel cell catalusts　2011年11月30日

︎全件表示 ︎最初の5件までを表示

産業財産権 4

  1. ナノ粒子およびナノ粒子の製造方法

    和田山智正, 轟直人, 高橋俊太郎

    特許7162336

    産業財産権の種類: 特許権

  2. アルカリ水電解システム、アルカリ水電解方法、及び水素の製造方法

    轟直人

    産業財産権の種類: 特許権

  3. アルカリ水電解システム、アルカリ水電解方法、及び水素の製造方法

    轟直人

    産業財産権の種類: 特許権

  4. オゾン発生用電極

    坂田 良真, 和田山 智正, 轟 直人, 石亀 弘基, 松本 聡

    産業財産権の種類: 特許権

共同研究・競争的資金等の研究課題 20

  1. ＤＡＣによるカーボンステーション開発事業

    山添誠司, 轟直人, 内田さやか

    2024年4月 ～ 2027年3月

  2. 再生可能エネルギー由来の変動電力環境で高活性を維持する非イリジウム系酸素発生触媒構造の解明

    轟直人

    2024年4月 ～ 2026年3月

  3. アルカリ電解電極の変動入力電源利用時の課題抽出

    轟直人

    2021年4月 ～ 2025年3月

  4. カルバゾールデンドリマー修飾による電気化学的二酸化炭素還元触媒の高活性・高選択化

    轟直人, アルブレヒト建

    2023年4月 ～ 2024年3月

  5. ルチルヘテロ構造を利用した異方歪みの導入による水電解触媒の高活性化

    轟直人

    2022年6月 ～ 2024年3月

  6. 水電解触媒の省貴金属化に向けたマルチフェイズ界面設計

    轟 直人

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    研究種目：Grant-in-Aid for Scientific Research (B)

    研究機関：Tohoku University

    2021年4月 ～ 2024年3月

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    本年度は、触媒-担体二相界面における相互作用を調査するためのモデルとして、Ru酸化物触媒/酸化物中間層/Ti酸化物からなる単結晶ヘテロ構造を用い、その酸素発生触媒特性を評価した。各層の作製にはアークプラズマ蒸着法を用い、構造評価には走査型電子顕微鏡、in-planeX線回折、原子間力顕微鏡、X線光電子分光法を用いた。触媒活性は窒素パージした過塩素酸溶液中で分極曲線を測定し評価した。触媒耐久性は定電流密度でのクロノポテンショメトリーにより評価した。 酸化物中間層はIr酸化物、Sn酸化物とした。初期の酸素発生触媒活性はIr酸化物を中間層とした場合は、中間層なしの場合とほとんど変わらなかったが、Sn酸化物を中間層とした場合に活性が大幅に向上した。電気化学インピーダンス測定、およびin-planeX線回折の結果から、Sn酸化物を中間層とすることにより、触媒/Ti担体間の抵抗が低減するだけでなく、Ru酸化物触媒層に加わる圧縮ひずみが緩和され、触媒活性そのものも向上することが明らかになった。また、クロノポテンショメトリーによる耐久性評価では中間層なしの場合に対し、Ir酸化物、Sn酸化物を中間層とした場合、過電圧の上昇幅が小さくなった。中間層なしの場合インピーダンス測定で評価した電極抵抗が増加していた一方、中間層ありの場合電極抵抗はほとんど変化しておらず、中間層を挿入することによりRu酸化物触媒/Ti酸化物担体間の界面が安定化することが示された。

  7. 異方歪みの能動的制御による二酸化炭素の高効率・高選択変換

    2020年11月 ～ 2024年3月

  8. 表面ドーピングによるステンレス鋼水電解電極高耐食化のための基盤技術開発

    2021年7月 ～ 2023年6月

  9. 金属/酸化物異相界面を利用した面欠陥導入による水電解触媒の高機能化

    轟直人

    2020年9月 ～ 2022年8月

  10. 水電解酸素発生触媒の高活性化に向けた積層欠陥の機能探索

    2020年7月 ～ 2021年6月

  11. CO2フリー水素大量生成のための酸化物歪みマネジメント 競争的資金

    轟 直人

    2019年4月 ～ 2021年3月

  12. ステンレス鋼を水電解触媒として高機能化する革新的表面改質技術開発 競争的資金

    轟 直人

    2018年4月 ～ 2021年3月

  13. 鉄鋼材料の水電解触媒利用に向けたアークプラズマ蒸着法による表面改質技術開発 競争的資金

    轟 直人

    2018年4月 ～ 2019年3月

  14. 鉄の電気化学的酸化還元挙動に関する表面科学的研究 競争的資金

    轟 直人

    2017年4月 ～ 2019年3月

  15. 3D活性サイト制御による高性能ナノ分子触媒の創製

    野村 琴広, 満留 敬人, 平野 雅文, 本倉 健, 高谷 光, 高尾 昭子, 和田山 智正, 轟 直人, 高谷 光, 稲垣 昭子

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research

    研究種目：Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    研究機関：Tokyo Metropolitan University

    2014年7月 ～ 2019年3月

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    新学術領域研究の連携による３Ｄ活性サイト解析の対象となる分子結晶・触媒活性種や担持ナノ触媒、特に特異な触媒作用を示す有機金属触媒やナノ粒子触媒、協奏機能触媒表面の設計・合成と反応化学や電子・構造解析に基づく活性サイト解析に取り組んだ。温和な条件下でのアミドの還元などに高活性・高選択性を発現する回収・再利用容易な高機能担持ナノ粒子触媒、既報より一桁高いオレフィンのヒドロシリル化活性を示す協奏機能表面触媒、オレフィンメタセシス重合に有効な高性能バナジウム触媒など、次世代型の革新的高性能触媒を創製した。また、今迄分析不可能なバナジウム触媒溶液の活性種解析を可能とする溶液XAFS法を確立した。

  16. ナノ構造制御合金表面系の物理構築に基づいたオンボード脱水素触媒のラボレベル開発

    和田山 智正, 田邉 匡生, 轟 直人

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research

    研究種目：Grant-in-Aid for Scientific Research (A)

    研究機関：Tohoku University

    2014年4月1日 ～ 2018年3月31日

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    エネルギーキャリア分子などの電極表面における反応特性と実触媒表面の原子配列・構造との関係を原子・分子レベルで検討するための要素技術開発、並びに脱水素反応や直接エタノール型燃料電池の電極反応、さらに二酸化炭素の電気化学還元に有効な触媒のラボレベル開発を目指したものである。具体的には、分子線エピタキシ(MBE)法によりPtやAuの基本低指数単結晶基板（M(hkl)）に第2元素Xを添加して作製したX/M(hkl)について、その表面構造解析や表面電気化学応答や反応過電圧の検討結果に基づき、過電圧の低い触媒を得る上で適切な合金最表面原子配列・組成を議論した。

  17. ナノ細孔空間を利用した革新的二酸化炭素変換触媒の創製 競争的資金

    轟 直人

    2017年4月 ～ 2018年3月

  18. 金属間化合物制御によるコア－シェル型触媒の高機能化 競争的資金

    轟 直人

    2015年4月 ～ 2017年3月

  19. 構造規制された酸化物－金属ハイブリッド触媒の創製と金属―空気電池への応用 競争的資金

    轟 直人

    2015年4月 ～ 2017年3月

  20. ナノポーラス構造を利用した高選択的高効率CO2変換触媒の開発 競争的資金

    轟 直人

    2016年1月 ～ 2016年12月

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担当経験のある科目(授業) 8

  1. 情報とデータの基礎　東北大学

  2. エネルギーや資源と持続可能性　東北大学

  3. 環境材料機能学特論　東北大学

  4. 先端環境創成学概論　東北大学

  5. 環境材料表面科学　東北大学

  6. 材料科学総合実験　東北大学

  7. 電気工学実験　東北大学

  8. 数学物理学演習Ⅰ　東北大学

︎全件表示 ︎最初の5件までを表示