Achieving Efficient Oxygen Evolution on High‐Entropy Sulfide Utilizing Low Electronegativity of Al

Abstract Efficient and stable catalysts are in high demand for accelerating the oxygen evolution reaction (OER). Herein, a high‐entropy sulfide (HES) of (FeCoNiCrCuAl)S@HCS with a 3D structure is successfully prepared by utilizing a simple one‐step solvothermal method and employed as catalyst toward OER. The lower electronegativity of Al compared to the other metal elements and its anti‐corrosion character enable an outstanding OER performance of (FeCoNiCrCuAl)S@HCS with an overpotential of 253 mV at 10 mA cm −2 and an excellent durability after 20 000 CV cycles, outperforming the commercial RuO 2 and most reported metal‐sulfide catalysts. Experiments coupled with theoretical calculations reveal that Al atom primarily serves as electron donor and promotes a redistribution of local electrons from Co and Cr toward adjacent Fe, Ni, and Cu sites. As a result, the Cr‐Al site possesses a lowest energy barrier during the rate‐determining step and works as the dominant active site for OER process. This study provides a novel insight and strategy into structural design and performance enhancement for HES materials.