Construction of Cs₂AgBiCl₆/COF Heterojunction for Boosted Photocatalytic Thioester Oxidation

Lead-free halide perovskites as a new kind of potential candidate for photocatalytic organic synthesis have attracted much attention recently. The rational heterojunction construction is regarded as an efficient strategy to delicately regulate their catalytic performances. Herein, a semi-conductive covalent organic framework (COF) nanosheet, C₄N, is employed as the functional component to construct Cs₂AgBiCl₆/C₄N (CABC/C₄N) heterojunction. It is found that the C₄N nanosheets with rich surface functional groups can serve as heterogeneous nucleation sites to manipulate the growth of CABC nanocrystals and afford close contact between each other, therefore facilitate the transfer and spatial separation of photogenerated charge carriers, as verified by in situ X-ray photoelectronic spectroscopy and Kelvin probe force microscopy. Moreover, the oxygen affinity of C₄N endows the heterojunctions with outstanding aerobic reactivity, thus improving the photocatalytic performance largely. The optimal CABC/C₄N heterojunction delivers a thioanisole conversion efficiency of 100% after 6 h, which is 2.2 and 7.7-fold of that of CABC and C₄N. This work provides a new ideal for the design and application of lead-free perovskite heterojunction photocatalysts for organic reactions.