Fabrication of In 2 S 3 /Zn 2 GeO 4 composite photocatalyst for degradation of acetaminophen under visible light.

A novel indium trisulfide/zinc germinate (In2 S3 /Zn2 GeO4 ) 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). Zn2 GeO4 nanorods work as the main photocatalyst while In2 S3 nanoparticles deposited on them acts as the photosensitizer. The resulting In2 S3 /Zn2 GeO4 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% In2 S3 showed the best activity for APAP degradation under visible light, with performance far superior to that of In2 S3 , nitrogen-doped titanium dioxide (N-TiO2 ), Degussa P25, and Zn2 GeO4 . 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 In2 S3 /Zn2 GeO4 composite. A probable reaction mechanism of APAP degradation under visible light over In2 S3 /Zn2 GeO4 heterojunction was proposed.