Abstract
Integrating water electrolyzers with intermittent renewable energy poses critical durability challenges from dynamic load fluctuations inducing catalyst degradation. We report a zinc-mediated sacrificial protection strategy enhancing NiMo catalyst stability through in situ dendritic passivation. Zinc-decorated NiMo on nickel felt (Zn-NiMo/NF) exhibits considerable hydrogen evolution activity (94.6 mV overpotential at 50 mA cm(-2)) comparable to Pt/C. Under stringent load fluctuation cycling protocols (-500/50 mA cm(-2)), the zinc overlayer spontaneously reconstructs into laterally oriented, NiMo-enriched dendrites providing dual protection: physical barriers suppressing dissolution (order-of-magnitude reductions in metal leaching) and sacrificial buffering wherein zinc preferentially oxidizes to zincate, shielding nickel from irreversible hydroxide formation. Zn-NiMo/NF maintains stable performance while pristine NiMo/NF degrades substantially. Anion exchange membrane electrolyzer validation confirms minimal voltage escalation over 100 h cycling (1.645- 1.667 V), outperforming Pt/C (1.7028-1.857 V). This establishes sacrificial interface engineering as an effective paradigm for robust earth-abundant electrocatalysts in renewable energy-integrated hydrogen production.