Research Progress on Composite Electrocatalysts for Alkaline Hydrogen Oxidation Reaction

The commercialization of anion exchange membrane fuel cells (AEMFCs) is hindered by the sluggish kinetics of the hydrogen oxidation reaction (HOR) under alkaline conditions, necessitating the development of electrocatalysts with high activity, long-term durability, and reduced noble-metal loading. Current understanding of the reaction mechanism has evolved from the conventional binary adsorption model based on catalyst–intermediate interactions to a more comprehensive dynamic framework involving catalyst–intermediate–interfacial<em> </em>water ternary cooperation. In recent years, composite electrocatalysts have emerged as promising candidates, where strategies such as interfacial electronic modulation, oxygen-vacancy engineering, hydrogen spillover, and bifunctional-site synergy have markedly optimized intermediate adsorption behavior and tailored the interfacial water environment. These advances have significantly enhanced alkaline HOR activity and resistance to poisoning. This review classifies composite electrocatalysts by the periodic groups of their constituent elements, covering oxides (groups IVB–VIIB), non-oxides such as carbides and nitrides, as well as the emerging single-atom catalysts. Recent progress in rational design, mechanistic insights, and performance optimization is summarized, with particular emphasis on the relationship between electronic/interfacial structure and catalytic activity. Building on these advances, the key challenges are identified and future opportunities are outlined.