Highly selective reduction of CO2 to CH4 mediated by 2D/0D Cs3Bi2Br9/BiOBr heterojunctions with atomic-level intimate interfaces

Exploring well-designed photocatalysts with high-quality interfaces for converting CO 2 into value-added chemical fuels faces a great challenge. Herein, a 2D/0D S-scheme heterojunction of Cs 3 Bi 2 Br 9 nanosheet/BiOBr nanocrystal (CBB/BOB) photocatalysts is designed and synthesized by an in-situ growth strategy for photocatalytic CO 2 reduction. The S-scheme heterojunctions with atomic-level intimate interfaces greatly accelerate the separation and transfer efficiency of photoinduced carriers and improve the reduction ability of photogenerated electrons resulting in prominent photocatalytic activity toward CO 2 photoreduction. Consequently, the environment-friendly hybrids show impressive photocatalytic CO 2 reduction efficiency and high CH 4 selectivity with a CH 4 yield and selectivity of 12.8 μmol g −1  h −1 and 79 %, respectively, which is 43 and 2 times higher than that of pristine CBB, respectively. The detailed experimental characterization and theoretical calculations indicate that the high adsorption/activation capability of CO 2 molecules and CO* intermediates and the lowered free energy of CO 2 reduction promote the photoconversion of CO 2 to CH 4 on the CBB/BOB heterojunctions. This work provides a new strategy for constructing perovskite-based photocatalysts for solar fuel applications.