Efficient removal of high concentration organic pollutants by ZnIn2S4 with highly active sulfur vacancy

Metal sulfides have attracted much attention because of their wide light response range and negative conduction band (CB) position, which can generate abundant charges to participate reduction and oxidation reactions. In recent years, efforts are devoted to enhance the charge separation and transfer to improve its overall performance in photocatalytic applications. Herein, we synthesized zinc indium sulfide (ZnIn2S4, named as ZIS) with S vacancy (VS) defects via a hydrothermal method with assist of excess sulfur sources. All the as-prepared samples exhibited significant photocatalytic degradation performance on organic pollutants with high concentration. Among them, the VS-ZIS (TAA) demonstrated exceptionally high photodegradation activity under visible light (lambda > 420 nm) irradiation, achieving removal rates up to 96 % and 90 % over TC (80 mg/L) and RhB (40 mg/L), respectively. Moreover, VS-ZIS (TAA) also displayed an excellent cycling stability. Combining experimental and theoretical studies, we unveil that the introduction of VS defects broadens the light absorption range, accelerates carrier separation and transfer, and provides additional surface active sites, thus improving the photocatalytic degradation efficiency. This study suggests that creating VS can induce effective charge separation, thus enhancing the photocatalytic activity and providing a viable pathway for treating high concentration organic pollutants.