Cobalt and sulfur co-doped TiO2 nanostructures with enhanced photo-response properties for photocatalyst

Cobalt (Co) and sulfur (S) co-doped titanium dioxide (TiO 2 ) catalysts were synthesized via sol–gel method. The structure of TiO 2 was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The valence states of elements were studied by X-ray photoelectron spectroscopy (XPS), and the optical-absorption properties of the catalysts were tested using the ultraviolet–visible (UV–Vis) spectrophotometer. The results showed that the grain sizes of Co and S co-doped TiO 2 decreased with the increase of Co and S doping concentration within a certain range, and then the catalysts had obvious red shift on the absorption of visible light. Sample (2%Co–5%S–TiO 2 ) showed excellent light absorption characteristics and the photo-response threshold increased significantly to about 760[Formula: see text]nm. Also, the further degradation test under visible light shows the 2%Co–5%S-TiO 2 sample exhibit apparently improved degradation efficiency for Rhodamine B compared to the undoped one.