Recent Advances in Polyoxometalate‒Metal Nanocluster Hybrids

Polyoxometalates (POMs) are structurally well-defined anionic metal-oxo clusters with diverse structural forms and distinctive physicochemical properties, including acidity/basicity, redox activity, and optical behavior. Over the past two decades, POMs have garnered increasing attention in metal nanocluster synthesis owing to their ability to impart unique structural and functional characteristics to these compounds. Initially, research in this field primarily focused on hybrid materials composed of POMs and metal nanoclusters stabilized by organic ligands. However, more recently, studies have demonstrated that POMs can themselves act as effective stabilizing ligands for the synthesis of atomically precise metal nanoclusters. These POM-stabilized metal nanoclusters exhibit synergistic and cooperative properties of metal nanocluster and POM components, enabling novel applications in fields such as catalysis, photochemistry, sensing, and electrochemistry. Notably, recent investigations into POM-metal nanocluster hybrids have demonstrated their potential as atomically precise counterparts to metal nanoparticle catalysts supported on bulk metal oxides, exhibiting the unique cooperative catalysis. This review provides a concise overview of POM‒metal nanocluster hybrids, with an emphasis on recent advancements in synthetic methodologies, properties, and applications. Additionally, solid-state synthetic strategies leveraging the rigid structures and redox properties of POMs for the controlled formation of metal nanoclusters are discussed.