Polyoxometalate electrocatalysts supported on nickel foam for enhanced oxygen evolution in alkaline media

The oxygen evolution reaction (OER) remains a major kinetic bottleneck in alkaline water electrolysis, requiring electrocatalysts that combine high activity, durability, and scalability at industrially relevant current densities. Polyoxometalates (POMs), owing to their well-defined metal–oxo architectures and rich redox chemistry, have emerged as versatile electronic modulators and functional building blocks for OER catalysis. This review summarizes recent advances in transition metal (TM)-based POMs integrated onto three-dimensional (3D) nickel foam (NF) supports (POM/NF) for the OER, including individually employed POM clusters, POM hybrids with diverse TM-based compounds such as layered double hydroxides, oxides, sulfides, and phosphides, as well as POM-based metal–organic frameworks. In these synergistic systems, TMs serve as the primary active sites, POMs enable charge delocalization and electronic modulation, and the NF scaffold offers a mechanically robust, highly conductive, and porous architecture that enables efficient charge transport. Thus, TM-based POM/NF electrocatalysts are discussed with emphasis on synthesis strategies, structural and interfacial engineering, and mechanistic insights. Key achievements include enhanced catalytic activity, improved durability in alkaline media, and stable operation at high current densities, while remaining challenges related to POM stability, synthesis reproducibility, and scale-up are critically discussed. Future perspectives highlight the concurrent optimization of robust POM chemistries and 3D NF architectures, where stable POM frameworks enable precise electronic modulation of the POM/NF materials while NF provides scalable, conductive, and mechanically resilient platforms. Then, the integration of POM/NF materials into practical OER devices, supported by advanced operando characterization and theoretical studies, is expected to guide the development of next-generation practical OER electrocatalysts.