A Three‐in‐One Integrated Cs3Bi2Br9@Co3O4 Heterostructure with Photoinduced Self‐Heating Effect for Synergistically Enhancing the Photothermal CO2 Reduction

Abstract Photothermal catalysis, which applies solar energy to produce photogenerated e − /h + pairs as well as provide heat input, is recognized as a promising technology for high conversion efficiency of CO 2 to value‐added solar fuels. In this work, a “shooting three birds with one stone” approach is demonstrated to significantly enhance the photothermal CO 2 reduction over the Cs 3 Bi 2 Br 9 @Co 3 O 4 (CBB@Co 3 O 4 ) heterostructure. Initially, Co 3 O 4 with photoinduced self‐heating effect serves as a photothermal material to elevate the temperature of the photocatalyst, which kinetically accelerates the catalytic reaction. Meanwhile, a p–n heterojunction is constructed between the p‐type Co 3 O 4 and n‐type Cs 3 Bi 2 Br 9 semiconductors, which has an intrinsic built‐in electric field (BEF) to facilitate the separation of photogenerated e − /h + pairs. Furthermore, the mesoporous Co 3 O 4 matrix can afford abundant active sites for promoting adsorption/activation of CO 2 molecules. Benefiting from these synergistic effects, the as‐developed CBB@Co 3 O 4 heterostructure achieves an impressive CO 2 ‐to‐CO conversion rate of 168.56 µmol g −1 h −1 with no extra heat input. This work provides an insightful guidance for the construction of effective photothermal catalysts for CO 2 reduction with high solar‐to‐fuel conversion efficiency.