Synergistic Interface Engineering of Ni 0.2 Mo 0.8 N/MoO 2 Heterostructure Catalysts for Accelerated Hydrogen Evolution in Alkaline Water and Seawater

Abstract The development of efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) in alkaline seawater electrolytes remains a formidable challenge, hindered by sluggish reaction kinetics and chloride‐induced corrosion. Herein, a synergistic interface engineering strategy is developed to fabricate hierarchical Ni 0.2 Mo 0.8 N/MoO 2 heterostructured rod arrays composed of nanoparticle assemblies. This design integrates conductive Ni 0.2 Mo 0.8 N domains with MoO 2 phases, leveraging metal–support interactions to enhance water adsorption/dissociation kinetics and proton adsorption/activation capacity. Consequently, this catalyst achieves ultralow overpotentials of 30/212 mV (alkaline freshwater) and 44/217 mV (alkaline seawater) to drive current densities of 100/1000 mA cm −2 , respectively, outperforming commercial Pt/C and state‐of‐the‐art transition metal‐based catalysts. Notably, in chloride‐containing alkaline seawater, it demonstrates remarkable stability by sustaining 200 mA cm −2 for 550 h. Theoretical calculations reveal that the Ni 0.2 Mo 0.8 N/MoO 2 heterointerface effectively modulates the electronic structure, significantly lowering the energy barriers for water dissociation and optimizing the adsorption/desorption capacity of hydrogen intermediates, ultimately enhancing catalytic performance. This work may provide a novel design framework for in situ construction of heterojunction catalytic systems, enabling industrial‐scale energy conversion.