Constructing RuNi‐MoO₂ Heterojunction with Optimal Built‐In Electrical Field for Efficient Hydrogen Production in Anion Exchange Membrane Water Electrolyzer

Abstract Water electrolysis in alkaline media, demonstrating robust facility and cheap electrolyzer construction, are regarded as a promising strategy for industrial green hydrogen generation. Exploring effective alkaline hydrogen evolution electrocatalysts is remained an obstacle to date, which requires additional effort to obtain active hydrogen by water dissociation and promote the following unfavorable hydrogen coupling for further H₂ release. Herein, the MoO₂ supported RuNi nanoparticle (RuNi‐MoO₂) is constructed as an efficient electrocatalyst for hydrogen evolution. Experimental and theoretical analysis demonstrate that the optimized built‐in electric field at the interface between MoO₂ and RuNi alloy simultaneously accelerates the water dissociation kinetics and hydrogen spillover. It attains the current densities of 10 and 100 mA cm⁻² at ultralow potential of −0.019 and −0.086 V versus RHE, respectively, along with rapid water cleavage kinetics, which even surpasses the commercial Pt/C. The constructing anion exchange membrane water electrolyzer adopting the RuNi‐MoO₂ as a cathode electrocatalyst attains an industrial current density of 1 A cm⁻² at a low voltage of 1.71 V and steadily operates over 1000 h with a large current density over 1 A cm⁻².