Improving the visible light photocatalytic activity of TiO2 by combining sulfur doping and rectorite carrier

Sulfur-doped TiO2/rectorite (STC) was prepared by an intercalation method using tetra-n-butyl titanate and dimethyl sulfoxide as the sources of Ti and S, respectively. A number of characterization methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption measurements, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis DRS) and photoluminescence spectroscopy (PL) were used to understand the properties of STC. It was found that the layer structure of rectorite was partly destroyed by intercalation, and the STC showed a looser porous lamellar structure with a large specific surface area (187.5 m2/g). By doping S into TiO2 lattice as Ti-O-S bond, the band gap of TiO2 was reduced from 3.2 to 2.8 eV. The removal of metronidazole by the STC under visible light irradiation for 240 min reached 93.8%, which was 71.8% higher than that of P25 TiO2. The improved photocatalytic activity was ascribed to the increased specific surface area, the narrowed band gap and the reduced electron-hole recombination.