Photocatalytic activity of (sulfur, nitrogen)-codoped mesoporous TiO ₂ thin films

Nitrogen and sulfur co-doped mesoporous TiO₂ thin films were fabricated using thiourea as a doping resource by the combination of the sol-gel and evaporation-induced self-assembly (EISA) processes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption, and UV-vis spectra were performed to characterize the assynthesized mesoporous TiO₂ materials. The XPS result shows that O-Ti-N and O-Ti-S bonds in the (S, N)-codoped mesoporous TiO₂ were formed. The resultant mesoporous (S, N)-codoped TiO ₂ exhibited anatase framework with a high porosity and a narrow pore distribution. After being illuminated for 3 h, methyl orange (MO) could be degraded completely by the co-doped sample under the ultraviolet irradiation, whereas mesoporous TiO₂ film without doping could only degrade 60% MO. After being illuminated by visible light, the water contact angles of the mesoporous co-doped TiO₂ samples decreased slightly, but the pure TiO₂ mesoporous film exhibited no change in the hydrophilicity.