Lead-Free Halide Perovskite Cs(2)AgBiBr(6)/Bismuthene Composites for Improved CH(4) Production in Photocatalytic CO(2) Reduction

[Image: see text] CO(2) photocatalytic conversion into value-added fuels through solar energy is a promising way of storing renewable energy while simultaneously reducing the concentration of CO(2) 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(2+) 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 Cs(2)AgBiBr(6) on a 2D bismuthene nanosheet prepared by a ligand-assisted reprecipitation method for a liquid-phase CO(2) photocatalytic reduction reaction. The composite improved the production and selectivity of the eight-electron CH(4) pathway compared with the two-electron CO pathway, storing more of the light energy harvested by the photocatalyst. The Cs(2)AgBiBr(6)/bismuthene composite shows a photocatalytic activity of 1.49(±0.16) μmol g(–1) h(–1) CH(4), 0.67(±0.14) μmol g(–1) h(–1) CO, and 0.75(±0.20) μmol g(–1) h(–1) H(2), with a CH(4) 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.