Study On Visible Light Photocatalytic Properties Of Nitrogen Or （and） Platinum Decorated TiO₂Prepared From Different Calcination Atmosphere

In the field of photocatalysis, TiO₂has been considered as a superperformance photocatalyst. Butbecause of its wide band gap （3.0³.2eV）, TiO₂can not utilize the visible light which accounts for a largeproportion of solar light energy. Therefore, it is a hotspot to extend the optical response of TiO₂to absorbvisible light. Doping TiO₂with extrinsic elements is an effective way to obtain visible-light photocatalyticactivities by narrowing its band gap. In this paper, the nanotube titanic acid （NTA） with one-dimensionaltubular structure was chosen as precursors and calcined in different atmosphere to prepare modified TiO₂doped with nonmetallic element N and metal elements Pt. Propylene was used as a target contaminant todetect photocatalytic activity of the samples. The specific content and results are as follows:（1）The N-TiO₂was synthesized by calcinating in flowing nitrogen and air through choosing NTA asprecursor, in association with urea as nitrogen source. The N-TiO₂was prepared under different calcinationconditions and the doped nitrogen was presented in different morphology and doping amount, whichthereby causes the diverse catalytic activities for the degradation of propylene. After the relevantexperimental characterization and analysis, it was revealed that the formation of SETOV in TiO₂matrixresults in visible light sensitization, while the little doped-N in interstitial sites functions to preventphotoinduced electrons and holes from recombination.（2） Pt-doped TiO₂samples were prepared by calcinating the resultant mixture which contained NTA orP25and chloroplatinic acid in flowing nitrogen and air. The results declared that Pt-doped TiO₂samplesprepared under different calcination conditions showed variant activities for degredation of propylene. Thevisible-light photocatalytic activity of Pt-TiO₂was proved to be related to the valence of Pt. The Pt²⁺ioncan boost the visible light activity, and the samples doped by Pt²⁺ion generally exhibited prominentphotocatalytic activities. While the Pt⁴⁺and Pt⁰existed in the samples are detrimental to the visible lightactivities and the corresponding samples showed no visible light activities.（3） TiO₂codoped with Pt and N was synthesized from NTA precursor, in association with urea solid asnitrogen source and chloroplatinic acid as platinum source respectively. The results indicated the existedchemical environment of Pt and N in codoped TiO₂is identical with that of samples doped by single element. It was proved that the two seperate procedures of nitrogen doping and platinum doping did notinfleunce to each other. The photocatalytic activity was evaluated by monitoring the oxidation of propyleneunder visible light irradiation. The photocatalytic activity of NPt-TiO₂was better than that of N-TiO₂andPt-TiO₂.