What X-ray absorption spectroscopy can tell us about the active state of earth-abundant electrocatalysts for the oxygen evolution reaction

Implementation of chemical energy storage for a sustainable energy supply requires the rational improvement of electrocatalyst materials, for which their nature under reaction conditions needs to be revealed. For a better understanding of earth-abundant metal oxides as electrocatalysts for the oxygen evolution reaction (OER), the combination of electrochemical (EC) methods and X-ray absorption spectroscopy (XAS) is very insightful, yet still holds untapped potential. Herein, we concisely introduce EC and XAS, providing the necessary framework to discuss changes that electrocatalytic materials undergo during preparation and storage, during immersion in an electrolyte, as well as during application of potentials, showing Mn oxides as examples. We conclude with a summary of how EC and XAS are currently combined to elucidate active states, as well as an outlook on opportunities to understand the mechanisms of electrocatalysis using combined operando EC-XAS experiments.

为实现可持续能源供应所需的化学储能技术，需对电催化剂材料进行合理优化，而揭示其在反应条件下的本征特性是优化的关键前提。为更好地理解地壳储量丰富的金属氧化物作为氧析出反应（OER）电催化剂的构效关系，电化学（EC）方法与X射线吸收光谱（XAS）的联用策略虽已展现出可观的研究价值，但仍存在未被充分挖掘的应用潜力。本文首先简要介绍了EC与XAS技术，并搭建了分析框架，用于讨论电催化材料在制备、储存、浸入电解质以及施加电位过程中所发生的结构变化，同时以锰氧化物作为示例展开说明。最后，本文总结了当前EC与XAS联用技术用于阐明电催化活性位点状态的研究进展，并对采用原位（operando）EC-XAS联用实验解析电催化反应机理的未来研究方向进行了展望。