The roles of polyoxometalates in photocatalytic reduction of carbon dioxide

As is well known, carbon dioxide (CO2) reduction reaction (CO2RR) by photocatalytic technology is a means with great promise to alleviate the crises on the global energy and the environmental fronts. It is critical to design and construct photocatalysts with high performance as catalysts are the core of the photocatalytic process. Recently, polyoxometalates (POMs) have aroused wide research interest as CO2 photoreduction-related catalysts because they possess tunable compositions, thermal stability, redox reaction and tailorable light-absorption capabilities. This review has discussed the recent progress of POMs and POM-based photocatalysts for CO2 reduction focusing on the roles of POMs as photocatalysts, cocatalysts, photocatalytic hosts (photosensitizers), and multi-electron donors in systems of CO2 photoreduction, which can provide important guides for the design of high-efficiency photocatalysts. In the end, based on summarizing the previous work, we make a prospect to the future research direction, key challenges, and possible solutions in this field.