The ambiguous mechanism of electrocatalysts for the oxygen evolution reaction (OER) greatly hinders their industrial applications toward renewable and clean energy conversion. Here, we elaborately prepared a cobalt sulfide catalyst to perform a comprehensive study of the OER performance under neutral/alkaline conditions. The combination of synchrotron-based operando X-ray spectroscopic investigations and electron microscopy observations captured a chameleon-like structural self-optimization on the cobalt sulfide oxygen evolution electrocatalyst in both neutral and alkaline electrolytes. Driven by the actual working conditions (pH gradient, electrical potential, etc.), distinct catalytic sites could be activated dramatically. In particular, the CoOOH supported on a single-walled carbon nanotube (CoOOH-SWCNT) with residual S species was identified as the true catalyst under alkaline conditions rather than the entirely transformed CoOOH-SWCNT, while the oxygenated CoS-SWCNT (O-CoS-SWCNT) was formed as the true catalyst under neutral conditions. Undoubtedly, such a mechanism of opening different locks with different keys and its microstructural advantages together guarantee the high catalytic activity in different electrolytes. This work provides a promising catalyst as well as sheds light on the very essence of the structural self-optimization process of catalysts. It makes a significant contribution to the advancement of OER relevant studies in the future while providing new ideas for the fields of chemistry and catalysis.

中文翻译：

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Operando X射线光谱法可观察到在放氧电催化剂上类似变色龙的结构重建

电催化剂用于氧气释放反应（OER）的机制不明确，极大地阻碍了其在可再生能源和清洁能源转化方面的工业应用。在这里，我们精心制备了硫化钴催化剂，以对中性/碱性条件下的OER性能进行全面研究。基于同步加速器的操作X射线光谱研究和电子显微镜观察相结合，在中性和碱性电解质中，硫化钴氧析出电催化剂都具有类似变色龙的结构自优化。由实际工作条件（pH梯度，电势等）驱动），不同的催化位点可以被显着激活。特别是，在碱性条件下，负载在具有残留S物种的单壁碳纳米管（CoOOH-SWCNT）上的CoOOH被确定为真正的催化剂，而不是完全转化的CoOOH-SWCNT，而被氧化的CoS-SWCNT（O-CoS -SWCNT）在中性条件下形成为真正的催化剂。毫无疑问，这种用不同钥匙打开不同锁的机制及其微结构优势共同保证了在不同电解质中的高催化活性。这项工作提供了有希望的催化剂，并且阐明了催化剂结构自优化过程的本质。