Recent advances of metal active sites in photocatalytic CO 2 reduction.

Photocatalytic CO 2 reduction captures solar energy to convert CO 2 into hydrocarbon fuels, thus shifting the dependence on rapidly depleting fossil fuels. Among the various proposed photocatalysts, systems containing metal active sites (MASs) possess obvious advantages, such as effective photogenerated carrier separation, suitable adsorption and activation of intermediates, and achievable C-C coupling to generate multi-carbon (C 2+ ) products. The present review aims to summarize the typical photocatalytic materials with MAS, highlighting the critical role of different formulations of MAS in CO 2 photoreduction, especially for C 2+ product generation. State-of-the-art progress in the characterization and theoretical calculations for MAS-containing photocatalysts is also emphasized. Finally, the challenges and prospects of catalytic systems involving MAS for solar-driven CO 2 conversion are outlined, providing inspiration for the future design of materials for efficient photocatalytic energy conversion.