A Three-in-One Integrated Cs 3 Bi 2 Br 9 @Co 3 O 4 Heterostructure with Photoinduced Self-Heating Effect for Synergistically Enhancing the Photothermal CO 2 Reduction.

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.