Stabilizing ZnIn2S4 via Phosphorus Doping for Efficient Photocatalytic Trifluoromethylation of Styrene

The heterogeneous semiconductor photocatalytic synthesis of organic molecules holds significant potential in green catalysis. In this work, we report the introduction of phosphorus (P) into ZnIn2S4 to achieve photocatalytic trifluoromethylation of styrene. Although P-doping does not enhance the yield of trifluoromethylacetophenone (28-30%, comparable to pristine ZnIn2S4), it significantly improves the photostability of the catalyst. Meanwhile, P-doping reduces the oxidation potential and enhances the separation efficiency of photogenerated charge carriers, radical trapping experiments and electron paramagnetic resonance confirmed the involvement of trifluoromethyl radical (•CF3), along with reactive oxygen species (ROS: •O2- and 1O2). Mechanistic investigations revealed that photogenerated holes oxidize CF3SO2Na to generate •CF3, which, together with ROS derived from electron reduction, promote the addition to styrene to form trifluoromethylacetophenone. This study provides a foundation for heterogeneous photocatalytic trifluoromethylation of unsaturated hydrocarbons in arenes.