In-situ synthesis of 3D microsphere-like In2S3/InVO4 heterojunction with efficient photocatalytic activity for tetracycline degradation under visible light irradiation

Semiconductor heterostructures have attracted extensive interest in photocatalytic degradation of antibiotic pollutants. In this study, a novel In2S3/InVO4 heterojunction was prepared via a simple in-situ anion exchange method by reacting pre-synthesized InVO4 microspheres with Na2S in an aqueous solution. The structures, morphologies and optical properties of the as-prepared samples were well characterized by XRD, SEM, EDS, TEM, XPS, N2 adsorption–desorption, UV–Vis absorption spectra, PL, photocurrent and electrochemical impedance spectroscopy. Benefiting from the enlarged visible light response and the formation of heterostructure, the as-prepared In2S3/InVO4 microspheres exhibit significantly promoted photocatalytic performance for the degradation of tetracycline (TC) under visible-light illumination. The optimum photocatalytic efficiency of In2S3/InVO4 composite was almost 2.26 and 11.71 times higher than that of In2S3 and InVO4, respectively. It also exhibited remarkable stability and repeatability. Radical trapping experiment and electron spin resonance results indicate that h+ and O2− are the main active species in the reaction system, and the role of OH can be ignored. The detailed photocatalytic mechanism is also proposed.