Fuel cell and water electrolyzer technology have been intensively investigated in the last decades toward sustainable and renewable energy conversion systems. For improved device performance and service life, nanostructured electrocatalysts on electrode have been extensively developed based on the principle of structure-activity-stability correlation. However, overall device efficiency is seriously hindered by sluggish oxygen electrocatalysis, including oxygen reduction reaction and oxygen evolution reaction. As a result, tremendous efforts have been made to construct the most active surfaces with robust durability. For knowledge-based approaches toward systematic development of highly functional nanostructures, fundamental principles within oxygen electrocatalysis should be uncovered including reaction intermediate, active site structures, and atomic dissolution from surface. However, conventional ex situ characterizations only provide a static picture of electrode surfaces without electrocatalysis. On the other hand, in situ/operando analyses allow us to directly monitor dynamics on electrode under operating conditions. In this review, we will introduce a set of in situ/operando analytical tools and summarize their contribution to fundamental researches on oxygen electrocatalysis. Taking both precious and non-precious electrocatalyst materials as examples, the most impending issues in oxygen electrocatalysis are covered with in situ/operando studies to highlight the power of in situ/operando techniques and encourage further efforts on advanced analytic techniques.

在过去的几十年中，对燃料电池和水电解技术进行了深入研究，以开发可持续和可再生能源转换系统。为了提高装置的性能和使用寿命，基于结构-活性-稳定性相关的原理，电极上的纳米结构电催化剂已经得到了广泛的开发。然而，缓慢的氧气电催化，包括氧气还原反应和氧气释放反应，严重阻碍了整个装置的效率。结果，已经做出巨大的努力来构造具有坚固耐用性的最活跃的表面。对于以知识为基础的系统化开发功能性纳米结构的方法，应该揭示氧电催化的基本原理，包括反应中间体，活性位点结构，和原子从表面溶解。但是，常规异位表征仅提供电极表面的静态图片，而无电催化作用。另一方面，原位/操作数分析使我们可以在操作条件下直接监视电极上的动态。在这篇综述中，我们将介绍一套原位/操作数分析工具，并总结它们对氧电催化基础研究的贡献。以贵金属和非贵金属电催化剂材料为例，氧气电催化中最紧迫的问题涵盖在原位/操作数研究中，以强调原位/操作数技术的力量，并鼓励在高级分析技术上作进一步的努力。