Research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts

With the increasing concerns to energy shortage and environmental problems in modern society, the development of cheap, clean, and sustainable energy alternatives has been attracting tremendous attention globally. Among various strategies of renewable energy exploration, solar-driven water splitting into its compositional elements H₂ and O₂ is an ideal approach to convert and store renewable solar energy into chemical bonds. In recent few decades, as an emerging new type of catalysts, polyoxometalates (POMs) have been widely utilized for water splitting due to their versatile synthetic methodology and highly tunable physicochemical and photochemical properties. This critical review addresses the research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts, including plenary POMs, transition-metal-substituted POMs, POM@MOF composites, and POM-semiconductor hybrids, under UV, near UV and visible light irradiation. In addition, the catalytic mechanism for each reaction system has been thoroughly discussed and summarized. Finally, a comprehensive outlook of this research area is also prospected.