Preparation and photocatalytic performance of magnetic TiO2–Fe3O4/graphene (RGO) composites under VIS-light irradiation

Abstract

In this work, TiO2–Fe3O4/grapheme (RGO) composites with good magnetism and photocatalytic activity were prepared by a facile hydrothermal method with RGO and magnetic TiO2 as starting materials in ethanol–water solvent. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), thermogravimetric and differential thermogravimetry analysis (TG-DTG), UV–vis diffuse reflectance spectra (UV–vis/DRS) and vibrating sample magnetometry (VSM). The results showed that the TiO2 coated Fe3O4 nanoparticles with a strong response to external magnetic fields were dispersed uniformly on the surface of RGO nanosheets. The composite catalysts can cause an obvious red shift of UV–vis spectra compared with pure TiO2. The adsorption and photocatalytic activity of the composite catalysts were evaluated by choosing methylene blue (MB) as organic pollutants. The photocatalytic degradation of MB by TiO2–Fe3O4/RGO composites under visible light irradiation was examined by varying the operational parameters such as catalyst amount, irradiation time, pH and initial MB concentration. The photocatalytic reactions obeyed pseudo-first-order kinetics according to Langmuir–Hinshelwood model. The repeatability of photocatalytic activity was also tested. A plausible mechanism was proposed and discussed on the basis of experimental results.