Interface regulation of ZnIn2S4/g-C3N4 S-scheme heterojunction for revealing exciton transfer mechanism and enhancing photocatalytic performance

The synergistic interaction between materials with specific dimensional nanostructures can establish high-speed transport channels for the internal and interfacial carriers of materials, which is important for promoting effective spatial separation of photogenerated carriers and improving photocatalytic performance. We fabricated ZnIn₂S₄ nanoparticles (GZIS) loaded with specific sizes on the surface of g-C₃N₄ ultrathin nanoplates (CNNs) using the calcined hydrothermal method to fabricate ZnIn₂S₄/g-C₃N₄ S-scheme heterojunctions. The activity of hydrogen evolution and degradation of Light Green SF (Yellowish) dyes was evaluated under visible light irradiation. The results showed that the hydrogen production rate of the photocatalyst GZIS–CN–0.8 was 7.431 mmol g⁻¹ h⁻¹, which was about 5.26 times that of pure ZnIn₂S₄ and 238 times that of g-C₃N₄ nanosheets. The degradation rate of GZIS–CN–0.8 for Light Green SF (Yellowish) dyes reached 90.2% within 120 min, which was much higher than that of pure ZnIn₂S₄ and g-C₃N₄ nanosheets. In addition, the charge transfer mode between the two materials interfaces is comprehensively investigated by density functional theory study and spectral analysis. The results show that the effective separation of interfacial charges in the heterojunction is a key factor to improve the photocatalytic performance. This work can provide a reference for the synthesis and interface design of efficient S-scheme photocatalysts.