This review focuses on the use of X-ray absorption and emission spectroscopy techniques using hard X-rays to study electrocatalysts under in situ/operando conditions. We describe the importance and the versatility of methods in the study of electrodes in contact with the electrolytes, when being cycled through the catalytic potentials during the progress of the oxygen-evolution, oxygen reduction and hydrogen evolution reactions. The catalytic oxygen evolution reaction is illustrated with examples using Co, Ni and Mn oxides, and Mo and Co sulfides are used as an example for the hydrogen evolution reaction. A bimetallic, bifunctional oxygen evolving and oxygen reducing Ni/Mn oxide is also presented. The various advantages and constraints in the use of these techniques and the future outlook are discussed.

中文翻译：

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使用硬 X 射线光谱法对电催化剂进行原位/操作研究

本综述重点介绍使用硬 X 射线的 X 射线吸收和发射光谱技术在原位/操作条件下研究电催化剂。我们描述了在氧析出、氧还原和析氢反应过程中通过催化电位循环时，研究与电解质接触的电极的方法的重要性和多功能性。以 Co、Ni 和 Mn 氧化物为例说明催化析氧反应，以 Mo 和 Co 硫化物为例进行析氢反应。还提出了双金属、双功能析氧和氧还原 Ni/Mn 氧化物。讨论了使用这些技术的各种优势和限制以及未来的前景。