Customizing ZnIn₂S₄ photocatalysts by regulating sulfur sources for C(sp³)-H transformation

Harnessing the power of photoredox catalysis for the selective C(sp³)-H activation and oxidation of alkyl aromatics represents a cutting-edge approach to transforming petroleum-derived feedstock into value-added C(sp³)-C(sp³) coupled chemicals. Herein, we delve into the photocatalytic process that involves the selective dehydrocoupling of ethylbenzene (EB) to access 2,3-diphenylbutane (DPB) alongside H₂, employing three sulfur source-varied ZnIn₂S₄ (denoted as ZIS-x) catalysts. ZIS-TAA, with thioacetamide (TAA) as the sulfur source, exhibits exceptional photocatalytic efficiency for DPB and H₂ production. The results show that the deficiency of charge carrier recombination centers in defect-poor ZIS-TAA is conducive to the separation of photogenerated charges. Additionally, the larger specific surface area and more surface functional groups provide abundant sites for reactant adsorption and activation, facilitating redox processes aided by an ideal band-edge structure. This work illustrates a simple and cost-effective paradigm for designing semiconductor-based photocatalysts with tailored surface properties to enhance the efficiency of target cooperative photoredox reactions.