A visible light response TiO 2 photocatalyst realized by cationic S-doping and its application for phenol degradation

Abstract

S-doped TiO 2 photocatalyst with high visible light activity was prepared by acid catalyzed hydrolysis method using thiourea (TU) as sulfur source. The catalyst was characterized by DRS, XPS, XRD, FTIR, SEM and N 2 adsorption. It was found that cation S 6+ was homogeneously incorporated into the bulk phase of TiO 2 and substitutes for some of the lattice titanium (Ti 4+). Doped S can form a new band above the valence band and narrow the band-gap of the photocatalyst, giving rise to a second absorption edge in the visible light region. The activity of the catalyst was examined by photodegradation of phenol in aqueous solution under both artificial visible light and solar light irradiation. The activity of catalyst was found to be dependent on the doping amount of S and the maximum activity was observed when the catalyst was obtained by calcinated at 600 °C with the mass ratio of TU/TiO 2 = 1. Too much of new-generated band-gap structures due to higher S-doping could act as recombination centers for electron–hole pairs. Catalyst with optimum S-doping exhibited the highest activity under both artificial light and solar irradiation for phenol degradation. In addition, doped S also beneficial for the better dispersion, large S BET and phase transformation retardation of TiO 2.