Tuning the Local H-rich Microenvironment by Armorial Chromic Oxide for Robust Ampere-Level Alkaline Hydrogen Evolution

Nickel sulfide (NiSx) catalysts typically suffer from sluggish kinetics and poor stability under ampere-level current densities in the alkaline hydrogen evolution reaction (HER). To address this, we construct Cr2O3-embedded Ni7S6 nanowires on nickel foam (Ni7S6−Cr2O3/NF) with tailored work function differences. Operando analyses and theoretical calculations reveal that interfacial charge redistribution creates a hydrogen-rich microenvironment by accelerating water dissociation at electron-deficient Cr sites and optimizing H* adsorption at electron-rich Ni sites. The catalyst achieves an industrially relevant current density of −1000 mA cm−2 at an overpotential of 369 mV and maintains stability for 1000 h due to the protective Cr2O3 layer. Furthermore, the assembled anion exchange membrane electrolyzer operates at only 1.86 V to deliver 1000 mA cm−2 and remains stable for 500 h. This work highlights interface engineering of local microenvironments as an effective strategy for developing industrial grade electrocatalysts for alkaline HER.