Composite of lead-free halide perovskite Cs3Bi2Br9 with TiO2 as an efficient photocatalyst for C(sp3)−H bond activation

Herein, a facile anti-solvent preparation strategy is proposed to fabricate lead-free halide perovskite Cs3Bi2Br9 with TiO2, which boosts photocatalytic activation of C(sp3)−H bonds in toluene oxidation. TiO2 not only works as nucleation center to reduce the particle size of perovskite, but could form type II heterojunction with Cs3Bi2Br9, thus improving the photocatalytic performance of the TiO2/Cs3Bi2Br9 composite. Under AM 1.5 G simulated sunlight irradiation, the optimal TiO2/Cs3Bi2Br9 composite exhibits both high production rate (9692.5 μmol g−1 h−1) and selectivity (91 %) of benzaldehyde product. As verified by in-situ ESR, in-situ FT-IR and DFT calculations, •O2− and h+ are demonstrated to be the main active species in this process. This work provides a new insight into the design of high-performance lead-free perovskite photocatalysts for organic synthesis.