Photocatalytic Hydrogen Production and Tetracycline Degradation Using ZnIn2S4 Quantum Dots Modified g-C3N4 Composites

In this work, ZnIn2S4/g-C3N4 (ZIS/CN) composites were synthesized by in-situ growth method, which showed excellent photocatalytic activity in the degradation of tetracycline and hydrogen production from water under visible light irradiation. ZnIn2S4 quantum dots (ZIS QDs) tightly combined with sheet g-C3N4 (CN) to accelerate the separation and transportation of photogenerated charges for enhanced photocatalytic activity. Among the prepared nanocomposites, 20%ZnIn2S4 QDs/g-C3N4 (20%ZIS/CN) delivered the highest photocatalytic activity. After 120 min of irradiation, the degradation rate of tetracycline with 20%ZIS/CN was 54.82%, 3.1 times that of CN while the rate of hydrogen production was 75.2 μmol·g-1·h-1. According to the optical and electrochemical characterization analysis, it was concluded that the excellent photocatalytic activities of the composite materials were mainly due to the following three points: enhancement in light absorption capacity, acceleration in the charge transport, and reduction in the carrier recombination rate through the formation of S-scheme heterojunction in the composite system. The high photocatalytic activity of ZIS/CN composites provides a new idea to develop highly efficient photocatalysts.