Enhanced photocatalytic degradation of tetracycline under visible light via a novel S-scheme Zn₃V₂O₈/ZnIn₂S₄ heterostructure construction

In the context of increasingly severe environmental pollution, it is crucial to develop effective photocatalytic materials to degrade antibiotics in water. We constructed a novel S-scheme heterojunction to enhance the photocatalytic performance of ZnIn₂S₄ by using an ultrasonic-assisted deposition method to integrate two-dimensional ZnIn₂S₄ nanosheets with Zn₃V₂O₈ nanoparticles. Advanced methods were employed to analyze the physicochemical characteristics of the synthesized materials systematically. Results indicated that adding Zn₃V₂O₈ significantly improved the photocatalytic performance of ZnIn₂S₄, with the loading amount influencing activity. The 10-Zn₃V₂O₈/ZnIn₂S₄ composite demonstrated remarkable photocatalytic efficiency, achieving a tetracycline degradation of 89.7 % within 60 minutes under visible light irradiation. Compared to pure ZnIn₂S₄ and Zn₃V₂O₈, this degradation rate was 5.87 and 6.76 times higher, respectively. The construction of the S-Scheme heterojunction leads to the formation of an internal built-in electric field, thereby enhancing the photocatalytic performance. The establishment of the built-in electric field significantly promotes the separation of photogenerated carriers while maintaining relatively high redox potentials. Additionally, density functional theory (DFT) calculations elucidated the electron transfer mechanism. Trapping experiments revealed that the degradation process was initiated by the combined effects of positive holes (h⁺), superoxide anions (·O₂^-), and hydroxyl species (·OH). This study offers valuable insights into developing efficient, stable photocatalysts for water pollutant removal.