CeO2-Stabilized Ni4MoAlloys as Robust Alkaline Hydrogen-Evolving Electrocatalysts for AnionExchange Membrane Water Electrolysis

Abstract The ampere-level alkaline hydrogen evolution reaction (HER) requires catalysts that combine high activity with long-term stability, yet benchmark NiMo alloys suffer from severe Mo leaching during operation. Here, we report a surface passivation strategy using CeO2-stabilized Ni4Mo alloys on MoO2 (CeO2–Ni4Mo/MoO2) for robust alkaline HER. Experimental and theoretical results reveal that surface CeO2 suppresses hydroxide-induced Mo dissolution while maintaining the reduced state of Ni4Mo and promoting interfacial water dissociation, thereby accelerating HER kinetics and increasing stability. Our catalyst delivers 1.0 A cm–2 at an overpotential of 165 mV and sustains hydrogen production for more than 3000 h with negligible decay. When used as the cathode in a platinum-group-metal-free AEM water electrolyzer, it achieves a value of 2.0 A cm–2 at 1.68 V, surpassing the DOE 2026 AEM benchmark of 2.0 A cm–2 at 1.8 V, and operates for 1200 h at 1.0 A cm–2 with a low degradation rate of 42.8 μV h–1.