Polyoxometalates in Photocatalytic CO ₂ Reduction: Multielectron Redox Regulation Across Molecular and Hybrid Architectures

The escalating concentration of atmospheric CO 2 has intensified the search for solar‐driven routes that convert carbon dioxide into value‐added fuels and chemicals. Photocatalytic CO 2 reduction offers a direct pathway toward carbon circularity; however, its realization is fundamentally constrained by inefficient charge separation, multielectron transfer requirements, competitive hydrogen evolution, and limited control over reaction selectivity. Polyoxometalates (POMs) have emerged as uniquely versatile platforms in this context due to their structurally programmable metal‐oxo frameworks and reversible multielectron redox chemistry. Acting as molecular electron reservoirs, charge‐transfer mediators, and coordination‐defined catalytic microenvironments, POMs provide an unusually direct handle over proton‐coupled electron transfer processes central to CO 2 activation and reduction. This review critically examines the roles of POMs across molecular, hybrid, and composite photocatalytic architectures. We categorize POM‐enabled systems into (i) intrinsic POM photocatalysts, (ii) photosensitizer‐assisted assemblies where POMs function as redox relays and electron buffers, (iii) POM‐metal‐organic complexes, and (iv) POM‐integrated semiconductor and MOF/COF heterostructures. By correlating structural motifs with charge‐regulation behavior, interfacial electron transport, and product distribution, we elucidate how POMs reshape reaction pathways and selectivity landscapes. Finally, we identify emerging design principles and outstanding challenges for advancing POM‐centered photocatalysts toward efficient visible‐light‐driven CO 2 conversion.