Construction of an S-Scheme ZnIn2S4/C3N4 Heterostructure for Photocatalytic H2O2 Generation: Performance Evaluation and Mechanistic Insights

The global demand for hydrogen peroxide (H2O2) continues to increase, and photocatalytic H2O2 production is regarded as a promising alternative technology due to its mild, safe, and environmentally friendly characteristics. ZnIn2S4 has demonstrated promising application potential in photocatalytic H2O2 production owing to its unique two-dimensional layered structure and broad spectral response. However, its performance is severely limited by rapid charge recombination and sluggish charge migration. To address this challenge, a ZnIn2S4/C3N4 S-scheme heterojunction was successfully constructed via a simple oil-bath method by assembling ZnIn2S4 nanoflowers on C3N4 nanosheets. Systematic structural characterizations and performance evaluations demonstrate that the construction of the S-scheme heterojunction effectively promotes the spatial separation and surface migration of photogenerated charge carriers, thereby significantly enhancing photocatalytic activity. Under optimal conditions, the ZIS/CN-10 sample (C3N4 to ZnIn2S4 mass ratio of 10%) achieves the highest photocatalytic H2O2 production rate of 825.8 μmol g−1 h−1. This work provides new insights and theoretical guidance for the rational design of efficient and stable ZnIn2S4-based photocatalysts.