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 RuO2 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.