Structure‐Function Relationship of p‐Block Bismuth for Selective Photocatalytic CO2 Reduction

Abstract

Selective photocatalytic reduction of CO2 to value‐added fuels, such as CH4, is highly desirable due to its high mass‐energy density. Nevertheless, achieving selective CH4 with higher production yield on p‐block materials is hindered by non‐ideal adsorption of *CHO key intermediate and an unclear structure‐function relationship. Herein, we unlock the key reaction steps of CO2 and found a volcano‐type structure‐function relationship for photocatalytic CO2‐to‐CH4 conversion by gradual reduction of the p‐band center of the p‐block Bi element leading to formation of Bi‐oxygen vacancy heterosites. The selectivity of CH4 is also positive correlation with adsorption energy of *CHO. The Bi‐oxygen vacancy heterosites with an appropriate filled Bi‐6p orbital electrons and p band center (‐0.64) enhance the coupling between C‐2p of *CHO and Bi‐6p orbitals, thereby resulting in high selectivity (95.2%) and productivity (17.4 µmol g‐1 h‐1) towards CH4. Further studies indicate that the synergistic effect between Bi‐oxygen vacancy heterosites reduces Gibbs free energy for *CO‐‐*CHO process, activates the C‐H and C=O bonds of *CHO, and facilitates the enrichment of photoexcited electrons at active sites for multielectron photocatalytic CO2‐to‐CH4 conversion. This work provides a new perspective on developing p‐block elements for selective photocatalytic CO2 conversion.