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 CO₂ to value‐added solar fuels. In this work, a “shooting three birds with one stone” approach is demonstrated to significantly enhance the photothermal CO₂ reduction over the Cs₃Bi₂Br₉@Co₃O₄ (CBB@Co₃O₄) heterostructure. Initially, Co₃O₄ 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 Co₃O₄ and n‐type Cs₃Bi₂Br₉ semiconductors, which has an intrinsic built‐in electric field (BEF) to facilitate the separation of photogenerated e⁻/h⁺ pairs. Furthermore, the mesoporous Co₃O₄ matrix can afford abundant active sites for promoting adsorption/activation of CO₂ molecules. Benefiting from these synergistic effects, the as‐developed CBB@Co₃O₄ heterostructure achieves an impressive CO₂‐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 CO₂ reduction with high solar‐to‐fuel conversion efficiency.