Constructing high entropy alloy/MoC heterostructure as efficient and stable catalysts for oxygen evolution reaction

Abstract

Due to the expensive cost of precious metals, there is an urgent need to develop cheap and efficient catalysts for the oxygen evolution reaction (OER). As a novel catalyst, high-entropy alloy (HEA) has found widespread application in the field of hydrogen production through water electrolysis. However, a significant portion of HEA catalysts prepared by traditional solvothermal methods are challenging due to their high cost, extended compound cycle, and relatively difficult electronic structure adjustment in the catalytic center. In this study, a heterostructure catalyst composed of MoC and FeCoNiMo HEA alloy (denoted as FeCoNiMo-M) was synthesized by the microwave method. Catalysts produced via the microwave method typically exhibit MoC encloses the spherical heterostructure of the internal high entropy alloy, MoC not only protects the true active center NiOOH, but even further regulates the electronic structure of the catalyst. Notably, the FeCoNiMo-M sample synthesized using microwave demonstrates an overpotential of merely 232 mV (@10 mA cm⁻²) in 1 M KOH, nearly 20 mV lower compared to the traditional hydrothermally-synthesized FeCoNiMo-H HEA catalyst. Furthermore, the FeCoNiMo-M catalyst demonstrates impressive durability in OER with a significant current density of 100 mA cm⁻² for a duration of 240 hours. The in-situ Raman results indicate that the FeCoNiMo-M catalyst undergoes the conversion of the actual reaction intermediate NiOOH and accelerates the OER with only a very low overpotential. These findings suggest that our approach could open up possibilities for the advancement of OER catalysts that are both more convenient and efficient.