Lead-Free Halide Perovskite CsAgBiBr/Bismuthene Composites for Improved CH Production in Photocatalytic CO Reduction.

CO photocatalytic conversion into value-added fuels through solar energy is a promising way of storing renewable energy while simultaneously reducing the concentration of CO in the atmosphere. Lead-based halide perovskites have recently shown great potential in various applications such as solar cells, optoelectronics, and photocatalysis. Even though they show high performance, the high toxicity of Pb along with poor stability under ambient conditions restrains the application of these materials in photocatalysis. In this respect, we developed an in situ assembly strategy to fabricate the lead-free double perovskite CsAgBiBr on a 2D bismuthene nanosheet prepared by a ligand-assisted reprecipitation method for a liquid-phase CO photocatalytic reduction reaction. The composite improved the production and selectivity of the eight-electron CH pathway compared with the two-electron CO pathway, storing more of the light energy harvested by the photocatalyst. The CsAgBiBr/bismuthene composite shows a photocatalytic activity of 1.49(±0.16) μmol g h CH, 0.67(±0.14) μmol g h CO, and 0.75(±0.20) μmol g h H, with a CH selectivity of 81(±1)% on an electron basis with 1 sun. The improved performance is attributed to the enhanced charge separation and suppressed electron-hole recombination due to good interfacial contact between the perovskite and bismuthene promoted by the synthesis method.