Anions-Exchange-Induced Efficient Carrier Transport at CsPbBr_xCl_3-x/TiO₂ Interface for Photocatalytic Activation of C(sp³)−H bond in Toluene Oxidation

Inspired by the unique band structure of CsPbBr₃, we have developed an asymmetric Cl-exchange strategy based on the CsPbBr_xCl_3-x/TiO₂ heterojunction-type catalyst and achieved photocatalytic activation of C(sp³)−H bond using the toluene oxidation reaction as a proof-of-concept application. The anion exchange at the supported CsPbBr₃ surface results in the CsPbBr_xCl_3-x/TiO₂ structure with an asymmetric distribution of halide. The resultant heterojunction-type catalysts exhibit significantly improved photocatalytic activity for toluene oxidation reaction with the highest benzaldehyde production rate at 1874 μmol g⁻¹ h⁻¹ (∼4 times that of the naked CsPbBr₃ nanocrystals). The remarkable photocatalytic performance can be ascribed to the improved carrier transport at CsPbBr_xCl_3-x/TiO₂ interface enabled by the unique band structure due to the asymmetric halide distribution, verified by the micro-strain discovered through the X-ray diffraction. This work demonstrates a new pathway to fabricate highly-efficient halide perovskite heterojunction-type catalysts for photocatalytic activation of C(sp³)−H bond.