Direct Detection of Fe<sup>VI</sup> Water Oxidation Intermediates in an Aqueous Solution
Chao Feng, Xianghua She, Yequan Xiao, Yanbo Li
Abstract
Abstract In situ detection of highly‐oxidized metal intermediates is the key to identifying the active center of an oxygen evolution reaction (OER) catalyst, but it remains challenging for NiFe‐based catalysts in an aqueous solution under working conditions. Here, by utilizing the dynamic stability of the Fe VI O 4 2− intermediates in a self‐healing water oxidation cycle of NiFe‐based catalyst, the highly‐oxidized Fe VI intermediates leached into the electrolyte are directly detected by simple spectroelectrochemistry. Our results provide direct evidence that Fe is the active center in NiFe‐based OER catalysts. Furthermore, it is revealed that the incorporation of Co into NiFe‐based catalyst facilitates the formation of Fe VI active species, thus enhancing the OER activity of NiCoFe‐based catalyst. The insights into the mechanisms for the sustainable generation of Fe VI active species in these NiFe‐based catalysts lay the foundation for the design of more efficient and stable OER catalysts.