Surface modification of ZnIn2S4 layers to realize energy-transfer-mediated photocatalysis

Photocatalytic selective aerobic oxidation reactions are crucial in designing advanced organic intermediates, but suffer from low conversion efficiency. Hence, activating O2 to create suitable reactive oxygen species, such as singlet oxygen (1O2), can significantly increase the yield of desired products. Herein, using ZnIn2S4 nanosheets as a model system, we build a surface-modified theoretical structure, where a surface-covered non-conductive macromolecular chain, polyvinyl pyrrolidone (PVP), is bound to ZnIn2S4 and influences the O2 adsorption process. PVP on the surface significantly changes the electronic structure and suppresses electron conduction of ZnIn2S4 nanosheets. Therefore, abundantly photogenerated and long-lived species transfer their energy to physically absorbed O2 to efficiently generate 1O2, which can oxidize sulphides into their corresponding sulphoxides. For sulphoxidation of different sulphides, surface modification brings a 3-9-fold increase in conversion efficiency and high selectivities ≥98%. This study provides a feasible way of boosting 1O2-generation-related photocatalytic reactions.