Structure-Function Relationship of p-Block Bismuth for Selective Photocatalytic CO 2 Reduction.

Selective photocatalytic reduction of CO 2 to value-added fuels, such as CH 4 , is highly desirable due to its high mass-energy density. Nevertheless, achieving selective CH 4 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 CO 2 and found a volcano-type structure-function relationship for photocatalytic CO 2 -to-CH 4 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 CH 4 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 CH 4 . 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 CO 2 -to-CH 4 conversion. This work provides a new perspective on developing p-block elements for selective photocatalytic CO 2 conversion.