Spectroscopic study for photocatalytic decomposition of organic compounds on titanium dioxide containing sulfur under visible light irradiation

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 (λ>400 nmλ>400 nm). It was also confirmed by IR spectroscopy that acetaldehyde in oxygen under visible light irradiation (λ>400 nmλ>400 nm) was decomposed to acetic acid by the S–TiO2 and ST-01 at the first decomposition step.

The S-containing TiO2 (1 M) exhibited higher photocatalytic activity than the commercial anatase type TiO2 (ST-01) for degradation of methylene blue in an aqueous solution under visible light irradiation (λ>400 nmλ>400 nm).Figure optionsDownload as PowerPoint slide