Sacrificial Cu leaching and molybdate oxoanion-induced suppression of over-oxidation for stable high-entropy-designed anode catalyst

초록

Green hydrogen production via water electrolysis is a key technology for achieving carbon neutrality. Anion exchange membrane water electrolysis (AEMWE) is particularly attractive because it enables high-current-density operation using non-precious metal catalysts. However, sluggish oxygen evolution reaction (OER) kinetics and transition-metal dissolution under high anodic potentials remain major challenges to efficiency and durability. Herein, we report a NiFeCoCuMo OER catalyst designed based on a high-entropy alloy concept and fabricated via one-step electrodeposition under ambient conditions. By introducing sacrificial Cu and electronically modulating Mo into a Ni-Fe-Co ternary alloy framework, we establish a rational strategy to simultaneously enhance OER activity and long-term stability. The NiFeCoCuMo catalyst exhibits an overpotential of 322 mV at 100 mA cm-2 in 1 M KOH and a low degradation rate of 0.21 mV h-1 over 100 h. When employed as an anode in an AEMWE single cell, it delivers 1 A cm-2 at 1.71 V, outperforming the benchmark IrO2. Mechanistic investigations suggest that sacrificial Cu leaching and the formation of molybdate oxoanion species mitigate over-oxidation of active Ni sites, thereby stabilizing the reconstructed oxyhydroxide phase under OER conditions. This work demonstrates a scalable electrodeposition-based, high-entropy-inspired compositional design strategy for developing active and durable non-precious OER anodes for green hydrogen production.

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