Boosting photocatalytic hydrogen evolution: Electronic redistribution of ZnIn2S4 nanosheets via halogen ion doping

Designing a visible light responsive photocatalyst is the path to enhancing the efficiency of solar power for hydrogen generation. Herein, we provide a method that makes use of doping I atoms to regulate the surface state of ZnIn2S4 (ZIS) nanosheets and enhance surface reaction processes in order to increase photocatalytic performance. The optimized I-ZIS photocatalyst achieves a high hydrogen yield of 4.73 mmol g−1 h−1, which is 29.56 folds more than pure ZIS. Experiment measurements and first-principles simulations demonstrate that the shallow energy level formed by I doping optimizes the local electronic distribution of ZIS, strengthens the electrons' delocalization capacity of S atoms for high electrical conductivity, and inhibits the regrouping of photo-generated electron and hole pairs, leading to an increase in the photocatalytic activity of the I-ZIS photocatalyst for hydrogen evolution. The research presents a novel viewpoint that a shallow energy level enhances the ability to separate photo-excited electron and hole pairs and accelerates the rate of hydrogen production.