Influences of various Pt dopants over surface platinized TiO2 on the photocatalytic oxidation of nitric oxide

Various surface platinized TiO2 were prepared by four different preparation methods and investigated with respect to their behaviors in UV photocatalytic oxidation of nitric oxide. The physicochemical properties of the Pt modified TiO2 were investigated by X-ray diffraction analysis, X-ray photoelectron spectrum analysis, transmission electron microscopy, and photoluminescence spectra. From the experimental results, it was found that new electronic states were observed above the valence bands of PtOx-TiO2 and PtClx-TiO2. And the lifetime of electrons and holes was found prolonged in the PtOx-TiO2 catalysts. The activity tests showed that the dopants existed as metallic Pt and platinum chloride had little contribution to the photocatalytic oxidation of NO in gas phase. However, the dopant which existed as PtOx could improve the NO photocatalytic oxidation efficiency and the reaction rate. The photocatalytic activity of the 0.05 at% PtOx-TiO2 was nearly three times higher than that of the pure Degussa P25 with an inlet NO concentration of 200 ppm.