Surface and Defect Engineering Coupling of Charge Shuttle and Redox Site in Cs3Bi2Br9/g-C3N4 for Efficient Photocatalytic C(sp3)–H Bond Activation

Solar-driven organic synthesis using halide perovskites (HPs) has garnered much attention, but their unsatisfactory conversion efficiency limits further applications. Addressing charge dynamics and redox site issues is a straightforward approach to improving performance. Herein, we report the synergistic charge separation and active site modulation in lead-free Cs3Bi2Br9 HP using N-vacancy reticular g-C3N4 nanosheet for selective C(sp3)–H bond activation. This regulation exhibits a strong interfacial interaction, enabling effective charge transfer with more active sites. Theoretical calculations and experimental characterizations detailed enhanced charge separation and reduced energy barriers for surface photoredox reactions. When applied to toluene oxidation under simulated solar light, the optimized photocatalyst achieves a total conversion rate of 6865.3 μmol g–1 h–1 and an outstanding benzaldehyde selectivity of over 92%, outperforming most reported HP-based photocatalysts. This work offers a universal strategy for developing efficient HP photocatalysts for solar-to-chemical energy conversion.