Targeted reactant activation and spatial charge separation for efficient photocatalytic C(sp3)–H bond oxidation

Abstract

Semiconductor-based photo-redox catalysis offers a sustainable route for green organic synthesis, yet efficient C(sp³)–H bond oxidation remains challenging due to slow charge separation and limited surface reactivity. Here, we report a CsPCN (cesium doped polymeric carbon nitride)–Cs₃Bi₂Br₉ heterojunction that promotes efficient charge separation while retaining strong hole oxidation capability of Cs₃Bi₂Br₉ and superior oxygen and reactant activation ability of CsPCN. In situ experimental and theoretical studies confirm the photoelectron transfer pathway from Cs₃Bi₂Br₉ to CsPCN driven by the interfacial electric field, empowering efficient spatial charge separation and high affinity and activation capability toward oxygen and reactants. As a result, the heterojunction exhibits efficient C(sp³)–H bond oxidation performance and broad substrate applicability under visible-light irradiation, achieving a conversion rate of ethylbenzene to acetophenone up to 8420 µmol g⁻¹ h⁻¹, 4.3 times higher than blank Cs₃Bi₂Br₉ (1950 µmol g⁻¹ h⁻¹). This work demonstrates a rational heterostructure design strategy to couple charge separation with surface reactant activation for efficient lead-free perovskite based photocatalytic C(sp³)–H functionalization.