Fabrication of In2S3/Zn2GeO4 composite photocatalyst for degradation of acetaminophen under visible light

Abstract

A novel indium trisulfide/zinc germinate (In2S3/Zn2GeO4) composite was developed via a co-precipitation hydrothermal method. The as-prepared composite was characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectroscopy (DRS). Zn2GeO4 nanorods work as the main photocatalyst while In2S3 nanoparticles deposited on them acts as the photosensitizer. The resulting In2S3/Zn2GeO4 heterogeneous photocatalyst not only has enhanced visible light absorption, but also improved photo-generated charge transfer efficiency with remarkably high efficiency in decomposing acetaminophen (APAP). The composite photocatalyst with the mass ratio of 30% In2S3 showed the best activity for APAP degradation under visible light, with performance far superior to that of In2S3, nitrogen-doped titanium dioxide (N-TiO2), Degussa P25, and Zn2GeO4. The influences of various parameters (i.e., catalyst dosage, solution pH, and initial concentration of APAP) and background interference (humic acid (HA) and bicarbonate (HCO3–)) on the photodegradation efficiency for APAP were also discussed. The mechanistic studies revealed that holes and superoxide radicals are mainly involved in the photodegradation of APAP by In2S3/Zn2GeO4 composite. A probable reaction mechanism of APAP degradation under visible light over In2S3/Zn2GeO4 heterojunction was proposed.