Small ZnIn₂S₄ Nanosheets with Abundant Edge-Active Sites Modified with MoS₂ Nanosheets for Hydrogen Evolution

Due to their unique optical properties and large specific surface areas, two-dimensional (2D) layered materials hold great promise for a wide range of applications in photocatalysis. A one-step, low-temperature reflow method was employed to synthesize 2D small-sized ZnIn2S4 (S-ZIS) nanosheets with the assistance of CH3NO and C6H5Na3O7 as surfactants. The synthesized S-ZIS, consisting of preferentially exposed edge facet (102) with an average size of approximately 200 nm, exhibited a larger specific surface area and shortened carrier lifetime compared to traditional ZnIn2S4 (ZIS). Furthermore, the separation and migration of photogenerated electron–hole pairs in MoS2-modified S-ZIS (S-ZIS/MoS2) were effectively promoted due to the intimate contact between MoS2 and the S-ZIS interface. Under simulated solar light irradiation, the optimum hydrogen evolution rate was achieved for the binary S-ZIS/MoS2-3 heterostructure, reaching 21.66 mmol·g–1·h–1, which was 3 and 21 times higher than that of S-ZIS and ZIS, respectively. Additionally, an apparent quantum yield (AQY) of 76% was achieved at 400 nm. This study provides valuable insights into the reasonable design and optimization of 2D heterostructures with preferably exposed edge-active sites and offers an innovative strategy for the development of efficient composite photocatalytic systems.