Performance and mechanism of photocatalytic tetracycline degradation by AgInS2/ZnS composites

AgInS2 quantum dots and ZnS photocatalytic materials were prepared using low temperature liquid phase and solvothermal methods, followed by the formation of their composites (AgInS2/ZnS) of different proportions with the aid of grinding method. The catalysts were characterized by various morphological and structural analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) and fluorescence spectroscopy (PL), etc. The experimental results show that the optical characteristics of ZnS can be improved by loading AgInS2. To evaluate the performance of the catalysts, tetracycline was selected as the target toxin, and its degradation was evaluated with AgInS2/ZnS materials. The results show that when the amount of AgInS2 was 5%, AgInS2/ZnS exhibited the most excellent degradation performance. Under the irradiation of the simulated solar light, the catalyst removed 46% of tetracycline (40 mg & sdot;L-1) in 120 min. Compared with the bare ZnS, the degradation rate of AgInS2/ZnS composite was significantly improved. The mechanism of tetracycline degradation by composites was verified through the experiments of energy band structure analysis, active species capture, photocurrent and electrochemical impedance and photoluminescence. The effects of pH and common interfering ions on the degradation of the antibiotic were also explored. The ecological risk of the photocatalytic degradation of tetracycline by composites was predicted. Generally speaking, the prepared AgInS2/ZnS material showed excellent photo-catalytic degradation performance, and it is a new catalyst with great potential.