Highly Active and Stable MXene-Supported High-Entropy Alloy Catalysts for the Oxygen Evolution Reaction

The depletion of fossil fuels and growing environmental concerns are accelerating the development of clean hydrogen production technologies. Anion exchange membrane water electrolysis (AEMWE) has emerged as a promising approach owing to its cost-effectiveness and improved stability of nonprecious materials. However, its efficiency is restricted by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, we report a catalyst derived from a high-entropy alloy (HEA), CuFeMnCoNi-NC/MXene, which exhibits remarkable OER activity and durability. The catalyst achieves an overpotential of 267 mV at 10 mA cm –2 and a Tafel slope of 50.9 mV dec –1 . It also exhibits low charge-transfer resistance ( R ct = 3.4 Ω) and a large double-layer capacitance ( C dl = 27.2 mF cm –2 ), thereby enhancing the overall electrochemical performance. Notably, the catalyst demonstrates excellent durability, with the overpotential increasing by only 3 mV after 10,000 cyclic voltammetry (CV) cycles. An AEMWE electrolyzer assembled with this catalyst presents 1.91 A cm –2 at 2.0 V and operates at 1.0 A cm –2 for 20 h with a low degradation rate of 0.9 mV h –1 .