高分子電解質膜ナノ・メゾ構造内におけるプロトン輸送メカニズムの量子・分子論的解析

• Project/Area Number: 13J09722
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Fluid engineering
• Research Institution: Tohoku University
• Principal Investigator: 馬渕 拓哉 東北大学, 大学院工学系研究科, 特別研究員(DC1)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥3,600,000 (Direct Cost: ¥3,600,000); Fiscal Year 2015: ¥1,200,000 (Direct Cost: ¥1,200,000); Fiscal Year 2014: ¥1,200,000 (Direct Cost: ¥1,200,000); Fiscal Year 2013: ¥1,200,000 (Direct Cost: ¥1,200,000)
• Keywords: Grotthuss機構 / プロトン輸送 / 高分子電解質膜 / 固体高分子形燃料電池 / 分子動力学法

Outline of Annual Research Achievements

今年度は，ホッピング現象を考慮したプロトン輸送シミュレータを用いて電解質膜内におけるプロトン輸送メカニズムについて解析を行い，その成果は学術雑誌および国内・国際学会で発表した．
本研究ではホッピング現象を考慮するために，Empirical Valence Bond (EVB)法を基に改良を加えた独自の分子間相互作用のモデル関数を確立し，そのパラメータは量子化学計算の結果を基にホッピング時のエネルギー障壁を再現できるように決定した．これにより，従来は困難とされてきたホッピング現象をMD計算で扱うことを可能にした．さらに，同シミュレータを電解質膜モデルに導入し，ホッピング機構と電解質膜内部の数nm程度の大きさの水クラスター構造を同時に考慮した電解質膜内部での物質移動現象を解析し，これまで明らかにされてこなかったホッピング現象がプロトン輸送に与える影響を明確にした．同時に，得られたプロトン拡散係数は実験結果とよく一致しており，ホッピングモデルの妥当性が示された．この成果は，国際学術誌のJournal of Chemical Physicsに発表した．
また，上記シミュレータを用いて電解質膜内のプロトン伝導特性の解明と支配因子の特定を実施した．水クラスター構造に関して(i)各含水率における水クラスターサイズ分布，(ii)水分子の水素結合により形成される一連のネットワーク構造の長さ，(iii)水分子１つあたりの平均水素結合数，のデータからクラスターの大きさや連結性を定量的に評価した．また，これら構造特性の温度，圧力，含水率等のパラメータとプロトン拡散係数の関係性から，プロトン伝導特性と水クラスターの連結性（水チャンネル構造）に強い相関があることを突き止めた．さらに，この結果に基づき，効率的なプロトン輸送に必要な含水率を定量的に見積もる指標を提示することに世界で初めて成功した．この成果は，米国電気化学会雑誌のECS Transactionsに発表した．

Research Progress Status

27年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

27年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Molecular Dynamics Simulation of Proton Transport in Polymer Electrolyte Membrane (2015)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Journal Title: Journal of Nanoscience and Nanotechnology Volume: 15 Issue: 4 Pages: 2958-2963
  • DOI: 10.1166/jnn.2015.9647
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] A Modified Two-state Empirical Valence Bond Model for Proton Transport in Aqueous Solution (2015)
  • Author(s): Takuya Mabuchi, Akinori Fukushima and Takashi Tokumasu
  • Journal Title: Jounal of Chemical Physics Volume: 143 Issue: 1 Pages: 14501-14501
  • DOI: 10.1063/1.4926394
  • Peer Reviewed / Open Access
• [Journal Article] Molecular Dynamics Study of Proton Transport in Modeled Water Cluster Structure of Polymer Electrolyte Membrane (2015)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Journal Title: ECS Transactions Volume: 69 Issue: 17 Pages: 723-729
  • DOI: 10.1149/06917.0723ecst
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] An Improved EVB Model for Proton Transport in Polymer Electrolyte Membrane (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Journal Title: ECS Transactions Volume: 64 Issue: 3 Pages: 699-704
  • DOI: 10.1149/06403.0699ecst
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Effect of bound state of water on hydronium ion mobility in hydrated Nafion using molecular dynamics simulations (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Journal Title: Journal of Chemical Physics Volume: 141 Issue: 10 Pages: 1049041-1049048
  • DOI: 10.1063/1.4894813
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Large-scale Molecular Dynamics Simulations for Analyses of Transport Phenomena in Polymer Electrolyte Fuel Cell (2013)
  • Author(s): Takashi Tokumasu, Akinori Fukushima, Takuva Mabuchi, Yuta Sugaya
  • Journal Title: Journal of Computer Chemistry, Japan Volume: 12 Issue: 1 Pages: 8-15
  • DOI: 10.2477/jccj.2012-0021
  • NAID: 130003362974
  • ISSN: 1347-1767, 1347-3824
  • Peer Reviewed
• [Journal Article] ARevised EVB Model for Proton Transport in Hydrated Nafion Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Journal Title: ECS Transactions Volume: 58 Issue: 1 Pages: 261-269
  • DOI: 10.1149/05801.0261ecst
  • Peer Reviewed
• [Journal Article] Molecular Analysis of Proton and Water Transport in the Nanostructure of Polymer Electrolyte Membrane (2013)
  • Author(s): 馬渕拓哉, 徳増崇
  • Journal Title: TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B Volume: 79 Issue: 807 Pages: 2446-2455
  • DOI: 10.1299/kikaib.79.2446
  • NAID: 130003386341
  • ISSN: 0387-5016, 1884-8346
  • Peer Reviewed
• [Presentation] Reactive Molecular Dynamics Study of Proton Transport in Water Cluster Models of Polymer Electrolyte Membrane (2016)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: The First Pacific Rim Thermal Engineering Conference
  • Place of Presentation: Hawaii（USA）
  • Year and Date: 2016-03-13
  • Int'l Joint Research
• [Presentation] 高分子電解質膜内におけるプロトン輸送および水クラスター構造特性の分子論的解析 (2015)
  • Author(s): 馬渕拓哉，徳増崇
  • Organizer: 第29回数値流体力学シンポジウム
  • Place of Presentation: 九州大学（福岡県春日市）
  • Year and Date: 2015-12-15
• [Presentation] Molecular Dynamics Study of Proton Transport in Modeled Water Cluster Structure of Polymer Electrolyte Membrane (2015)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: 228th Electrochemical Society Meeting
  • Place of Presentation: Phoenix（USA）
  • Year and Date: 2015-10-11
  • Int'l Joint Research
• [Presentation] 分子動力学法を用いた高分子電解質膜内におけるプロトン輸送現象の解析 (2015)
  • Author(s): 馬渕拓哉，徳増崇
  • Organizer: 日本機械学会2015年度年次大会
  • Place of Presentation: 北海道大学（北海道札幌市）
  • Year and Date: 2015-09-13
• [Presentation] 高分子電解質膜内におけるクラスター構造がイオン伝導性に与える影響の分子論的解析 (2015)
  • Author(s): 馬渕拓哉，徳増崇
  • Organizer: 第52回日本伝熱シンポジウム
  • Place of Presentation: 福岡国際会議場（福岡県福岡市）
  • Year and Date: 2015-06-03
• [Presentation] Molecular Dynamics Study of Water Cluster Properties in Polymer Electrolyte Membrane (2015)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: 5th International Symposium on Micro and Nano Technology
  • Place of Presentation: Calgary（Canada）
  • Year and Date: 2015-05-18
  • Int'l Joint Research
• [Presentation] An Improved EVB Model for Proton Transport in Polymer Electrolyte Membrane (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: 226th Electrochemical Society Meeting
  • Place of Presentation: Cancun, Mexico
  • Year and Date: 2014-10-05
• [Presentation] A Molecular Dynamics Study of Proton Hopping in Nafion Membrane (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: 4th Micro and Nano Flows Conference
  • Place of Presentation: London, UK
  • Year and Date: 2014-09-07
• [Presentation] A Molecular Dynamics Study of Proton Transport in Hydrated Nafion membrane (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: 9th Liquid Matter Conference
  • Place of Presentation: Lisbon, Portugal
  • Year and Date: 2014-07-21
• [Presentation] A Molecular Dynamics Study of Proton and Water Diffusivity in Polymer Electrolyte Membrane (2014)
  • Author(s): T. Mabuchi and T. Tokumasu
  • Organizer: The 5th International Conference on Heat Transfer and Fluid Flow in Microscale
  • Place of Presentation: Marseille, France
  • Year and Date: 2014-04-22
• [Presentation] Molecular Dynamics Study of Proton and Water Transport in Nafion Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Organizer: 11^<th> International Conference on Nanochannels, Microchannels, and Minichannels
  • Place of Presentation: Sapporo, Japan
• [Presentation] Molecular Simulation of Proton Transport in Polyelectrolyte Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Organizer: International Soft Matter Conference 2013
  • Place of Presentation: Rome, Italy
• [Presentation] Molecular Dynamics Simulation of Proton Transport in Polyelectroly te Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Organizer: The 4th International Symposium on Micro and Nano Technology
  • Place of Presentation: Shanghai, China
• [Presentation] ARevised EVB Model for Proton Transport in Hydrated Nafion Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Organizer: 224^<th> Electrochemical Society Meeting
  • Place of Presentation: San Francisco, USA
• [Presentation] Molecular Dynamics Study of Proton and Water Transfer in Polyelectrolyte Membrane (2013)
  • Author(s): T. Mabuchi, T. Tokumasu
  • Organizer: The 12^<th> International Symposium on Fluid Control, Measurement and Visualization
  • Place of Presentation: Nara, Japan
• [Remarks] http://www.ifs.tohoku.ac.jp/nanoint/jpn/