| Summary: | 碩士 === 長榮大學 === 職業安全與衛生學系碩士班 === 98 === Titanium dioxide (TiO2) is an n-type semiconducting photocatalyst. It can be activated to decompose the organic pollutants under UV light of wavelengths < 387.5 nm irradiation because of its large band gap of 3.2 eV. But the solar spectrum usually contains about 4% UV light. Consequently, in this study we describe the preparation of visible-light responsed photocatalysts with non-metallic nitrogen and phosphorus modified TiO2. Three series of nitrogen and phosphorus co-doped titanium oxide nanoparticles were obtained by a simple modified sol-gel method using ammonium hydroxide and ammonium hexafluorophosphate as the N and P sources. These modified samples were then calcined in air at different temperatures for 5h. The results were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), UV-VIS spectroscopy and Scanning electron microscope (SEM). The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under visible light. From the surface chemistry investigations of XRD, Raman, XPS, UV-VIS and SEM, the results showed that the particle size of N, P co-doped TiO2 were about 19~30 nm, 17~33 nm and 10~32 nm, respectively. The samples calcined above 400 oC were all anatase structure. N atoms replaced a part of oxygen sites in the TiO2 lattice and P atoms only existed in a pentavalent-oxidation state. The samples exhibited a absorption shoulder between 390~550 nm that the calcination temperature leads to a lowering amount of visible absorption. Furthermore, compared with Hombikat UV-100, Degussa P-25, N/TiO2 and P/TiO2, the N, P/TiO2 samples have a batter response of visible light.
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