Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.
A TiO2 modified with PtⅣ chloride was investigated by diffuse reflectance UV-Vis spectra（DRS）,X-ray photoelectron spectroscopy（XPS）, surface photovoltage spectroscopy（SPS） and electric field-induced surface photovoltage spectroscopy（EFISPS）.XPS showed that a Ti-O-PtⅣClx surface complex between PtⅣ chloride and TiO2 appears to be responsible for visible light absorption.An electron transfer from the surface-complexed PtⅣClx to the conduction band of TiO2 upon absorbing visible light was confirmed by SPS and EFISPS.
