Design and synthesis of two dimensional-ZnIn2S4 nanosheets with sulfur vacancies for improving photocatalytic hydrogen production performance

The remarkable properties exhibited by two-dimensional (2D) photocatalytic materials, differing from bulk materials, have captivated significant interest. In this study, a hexagonal-phase ZnIn2S4 were synthesized using thiosulfate, thioacetamide, and l-cysteine as sulfur sources (denoted as ZIS-A, ZIS-B and ZIS-C), respectively. The synthesized ZnIn2S4 exhibited varying morphologies and photocatalytic properties, which were characterized through XRD, SEM, TEM, EPR, XPS and so on. The results confirmed that ZIS-B with 2D nanosheets structures exhibited superior photocatalytic properties compared with that of the flower-like spheres and block ZnIn2S4 samples. The hydrogen evolution rate of the ZIS-B is 3653 ​μmol ​g−1 ​h−1, which is 3.1 times than that of the other samples. This improvement was attributable to that the ZIS-B have 2D nanosheets structures and sulfur vacancies. Notably, the 2D nanosheets structure endowed ZnIn2S4 with a larger surface area and abundant reactive sites for efficient evolution reaction. Additionally, the presence of sulfur vacancies served as active sites, facilitating carrier transport and ultimately promoting the rate of photocatalytic hydrogen evolution. These results present a novel method for optimizing 2D ZnIn2S4 photocatalyst to improve the photocatalytic hydrogen evolution.