Photoelectrochemical and electrochemical CO2 reduction to formate on post-transition metal block-based catalysts

Photoelectrochemical or electrochemical reduction of carbon dioxide (CO2) to produce formate is a potential strategy to reduce greenhouse gases. In the past few years, various catalysts and modification strategies have been developed to improve the selectivity and solar-to-formate conversion efficiency, accelerating the practical applications of this technology. Among them, more attention was paid to the post-transition metal block-based catalysts due to their high formate selectivity. Herein, representative post-transition metal block-based (indium (In), tin (Sn), bismuth (Bi), etc.) catalysts and engineering strategies in regulating the CO2 reduction selectivity and activity toward formate are summarized. First, the advantages and fundamental mechanism of CO2 reduction to formate were discussed. After that, an overview of selectivity and stability of catalysts, and in situ/operando characterization were discussed for deepening the understanding of the reaction mechanisms and catalyst design theory. Subsequently, the photoelectrochemical CO2 reduction systems were analyzed to provide insight for designing the structure of the photoelectrochemical device or cell. To conclude, the future challenges, concerns, directions, and applications are summarized and prospected.