Advances and Challenges in Catalysts for Proton Exchange Membrane Water Electrolysis

The development of low-cost, high-stability catalysts is central to accelerating the industrialization of proton exchange membrane (PEM) water electrolysis for hydrogen production and to supporting the global carbon neutrality goal. This review provides a comprehensive overview of the latest advances in PEM water electrolysis catalysts, with particular emphasis on structural optimization of noble metal catalysts and performance breakthroughs of non-noble metal catalysts. Recent studies demonstrate that the loading of precious metals (e.g., Ir <0.3 mgcm) can be significantly reduced while intrinsic activity is enhanced through approaches such as nanoengineering and alloying. Meanwhile, non-precious metal systemsincluding transition metal phosphates, sulfides, and single-atom catalystshave shown activity approaching that of precious metals. However, their rapid dissolution and deactivation in strongly acidic anodic environments (e.g., Fe dissolution >50% within 100 h) lead to operational lifetimes far below the industrial requirement (>1000 h). This paper further summarizes the mechanisms and effects of heterojunction construction, heteroatom doping, and strain regulation on catalytic performance, and discusses the role of catalytic layer architecture and membraneelectrode integration in determining macroscopic efficiency. Finally, existing gaps in industrial-level current density validation and mechanistic understanding of degradation are highlighted, pointing to research directions for future catalyst design and system integration toward next-generation high-performance PEM electrolyzers.