Cu‐Content Engineering in FeCoNiCuAl High‐Entropy Alloy Precursors: A Pathway to Advanced HEA‐Derived Sulfide Electrocatalysts for Efficient Oxygen Evolution Reaction

Abstract This study aims to investigate the effect of copper (Cu) content in the precursor alloy on the performance of high‐entropy sulfide (HES) electrocatalysts prepared by the hydrothermal method in oxygen evolution reaction (OER). Given the unique multi‐metallic structure of high‐entropy sulfides and their potential excellent electrochemical performance, HES electrocatalysts with different Cu contents were prepared by hydrothermal synthesis in this paper, and the effect of Cu content on the catalyst performance was systematically analyzed. The results show that when the molar ratio of Cu to other metals is 0.5, the performance of the corresponding HES electrode in OER is significantly improved. Specifically, at a current density of 10 mA·cm −2 , which has a lowest overpotential of 232.54 mV with a Tafel slope of 144.85 mV·dec −1 and excellent stability. The improved performance of the HES electrocatalyst can be attributed to the surface morphology optimization, improved conductivity, and enhanced entropy stability brought about by the adjustment of Cu content. In addition, the synergistic effect between metal elements improves the intrinsic activity and active site exposure of the catalyst, and the uniformity and surface consistency of the catalyst also enhance its stability. This study not only provides a theoretical basis for the preparation and application of HES electrocatalysts but also provides a new path for the development of energy conversion and storage technologies.