催化学报 ›› 2021, Vol. 42 ›› Issue (12): 2094-2104.DOI: 10.1016/S1872-2067(21)64088-3

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碱性介质中氢氧化反应电催化剂的开发: 从机理认识到材料设计

仇暘a, 谢小红a, 李文震b,c,#(), 邵玉艳a,*()   

  1. a西北太平洋国家实验室, 华盛顿, 美国
    b爱荷华州立大学化学与生物工程系, 爱荷华州, 美国
    c能源部艾姆斯实验室, 爱荷华州, 美国
  • 收稿日期:2021-01-18 接受日期:2021-01-18 出版日期:2021-12-18 发布日期:2021-04-25
  • 通讯作者: 李文震,邵玉艳

Electrocatalysts development for hydrogen oxidation reaction in alkaline media: From mechanism understanding to materials design

Yang Qiua, Xiaohong Xiea, Wenzhen Lib,c,#(), Yuyan Shaoa,*()   

  1. aPacific Northwest National Laboratory, Richland, Washington 99352, USA
    bDepartment of Chemical & Biological Engineering, Iowa State University, Ames, IA, USA
    cDOE’s Ames Laboratory, Ames, IA, USA
  • Received:2021-01-18 Accepted:2021-01-18 Online:2021-12-18 Published:2021-04-25
  • Contact: Wenzhen Li,Yuyan Shao
  • About author:# E-mail: wzli@iastate.edu
    * E-mail: yuyan.shao@pnnl.gov;

摘要:

阴离子交换膜(AEM)燃料电池因具有使用非贵金属作为催化剂的优点而受到广泛关注. 然而, 在碱性体系中, AEM燃料电池中氢氧化反应(HOR)的反应动力学比在酸性介质中的慢两个数量级. 针对HOR在碱中动力学缓慢的问题, 有两种主要的理论来解释, (1)pH相关的氢结合能作为主要影响因素来控制HOR动力学的理论; (2) 质子和氢氧根离子的吸附共同作为影响因子来控制HOR在碱性条件下的动力学的双功能理论.

本文首先讨论了在碱性电解质中可能的HOR反应机理及其Tafel性能变化. 除了传统的Tafel-Volmer和Heyrovsky-Volmer-HOR机理外, 还讨论了最新提出的氢氧根离子吸附参与的HOR机理来说明在酸性和碱性介质中HOR机理的差异. 然后, 总结了具有代表性的碱性HOR催化剂(如贵金属、合金、金属间化合物、镍基合金、碳化物、氮化物等), 简要介绍了它们相应的HOR反应机理, 从而进一步理解在碱性介质中不同基元反应步骤给HOR性能带来的差异. 最后, 提出了一种未来设计HOR碱性催化剂的可行性方案, 为今后碱性环境下的HOR催化剂设计提供参考.

关键词: 氢氧化反应, 碱性电解质, 燃料电池, 电催化剂, 电催化, 氢和氢氧离子结合能

Abstract:

Anion exchange membrane (AEM) fuel cells have gained great attention partially due to the advantage of using non-precious metal as catalysts. However, the reaction kinetics of hydrogen oxidation reaction (HOR) is two orders of magnitude slower in alkaline systems than in acid. To understand the slower kinetics of HOR in base, two major theories have been proposed, such as (1) pH dependent hydrogen binding energy as a major descriptor for HOR; and (2) bifunctional theory based on the contributions of both hydrogen and hydroxide adsorption for HOR in alkaline electrolyte. Here, we discuss the possible HOR mechanisms in alkaline electrolytes with the corresponding change in their Tafel behavior. Apart from the traditional Tafel-Volmer and Heyrovsky-Volmer HOR mechanisms, the recently proposed hydroxide adsorption step is also discussed to illustrate the difference in HOR mechanisms in acid and base. We further summarize the representative works of alkaline HOR catalyst design (e.g., precious metals, alloy, intermetallic materials, Ni-based alloys, carbides, nitrides, etc.), and briefly describe their fundamental HOR reaction mechanism to emphasize the difference in elementary reaction steps in alkaline medium. The strategy of strengthening local interaction that facilitates both H2 desorption and Hads + OHads recombination is finally proposed for future HOR catalyst design in alkaline environment.

Key words: Hydrogen oxidation reaction, Alkaline electrolyte, Fuel cell, Electrocatalyst, Electrocatalysis, Hydrogen and hydroxide binding energy