Synergistic Interface Engineering of Ni0.2Mo0.8N/MoO2 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.