title: Spectroscopic study for photocatalytic decomposition of organic compounds on titanium dioxide containing sulfur under visible light irradiation.
abstract: Yellowish S-containing TiO2 (S-TiO2) powders were prepared by calcination of a mixture of titanium(III) chloride and ammonium thiocyanate solutions. Three kinds of S-TiO2 were prepared by varying the concentration of ammonium thiocyanate (0.5, 1 or 13 M). X-ray photoelectron spectroscopy spectra of the S-TiO2 showed that sulfur atoms existed on the surface of TiO2 powders. But the peaks assigned to S disappeared after Ar+ etching, which means that these atoms were not doped in the bulk of the TiO2 powders. While UV-visible absorption spectra of S-TiO2 showed that the absorption edges of these photocatalysts were seen to shift to a longer wavelength (lower band gap energy) than those of undoped rutile TiO2 prepared and commercial anatase type TiO2 (ST-01). The S-TiO2 (1 M) exhibited higher photocatalytic activity than ST-01 for degradation of methylene blue in aqueous solution under visible light irradiation (lambda > 400 nm). It was also confirmed by IR spectroscopy that acetaldehyde in oxygen under visible light irradiation (lambda > 400 nm) was decomposed to acetic acid by the S-TiO2 and ST-01 at the first decomposition step.
authors.affiliation: Department of Chemical Science and Technology, Faculty of Engineering, The University of Tokushima, Tokushima 770-8506, Japan. katoh@chem.tokushima-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Katoh
authors.forename: Hironori
authors.initials: H
authors.lastname: Aihara
authors.forename: Toshihide
authors.initials: T
authors.lastname: Horikawa
authors.forename: Tahei
authors.initials: T
authors.lastname: Tomida