S-scheme CuInS2/ZnS heterojunctions for the visible light-driven photocatalytic degradation of tetracycline antibiotic drugs

Background: In last few years, the researchers from different communities are focusing the wastewater treatment of medical and aquaculture industry. More importantly, the antibiotic released from the hospitals and aquaculture badly effecting water bodies. Methods: In this work, a series of CuInS2/ZnS (CIS/ZnS) heterojunction nanomaterials are prepared through solvothermal method and analyzed using different techniques. The photocatalytic behavior of CIS/ZnS heterojunctions in the degradation of tetracycline hydrochloride (TCH) is investigated under visible light irradiation. Significant findings: The results show that up to 86% of TCH degrades in 3 h with the optimized CIS/ZnS(1:2) sample. The enhanced photocatalytic activity is attributed to the formation of S-scheme heterojunctions, which promotes charge separation and transportation in CIS/ZnS composite materials. The photocatalytic mechanism is elucidated based on the electron paramagnetic resonance technique, optical properties and charge/radical trapping experiments. The visible-light absorption ability is enhanced, and superoxide radical (O-center dot(2)-) is confirmed to be one of the main active species according to active substance capturing experiments. The high stability of CIS/ZnS composite provides a new way to design effective photocatalysts for the eradication of hazardous materials from environment.