| Summary: | 碩士 === 國立東華大學 === 物理學系 === 100 === In this research, phosphorus doped TiO2 nanoparticles have been prepared by sol-gel method. At first, to find the sample with best photocatalytic activity, samples have been prepared with different doping concentrations of phosphorus. Then the sample with best activity has been calcined at different temperatures in air and investigated by XPS, XRD, Raman, UV-vis and EPR techniques.
XPS results show that the phosphorous in the samples is in pentavalent oxidation state (P+5) and substitutes Ti4+ site. Uv-vis absorption spectra exhibit critical absorptions between 400nm to 430nm. MB degradation profiles indicate that the photocatalytic activity of phosphorus doped TiO2 is more enhanced than commercial titania P25 under visible light irradiation. Raman spectra show that for pure TiO2 sample phase transition occur at 700℃, where as phosphorus doped TiO2 sample heated from 400℃ to 800℃ is in anatase phase and the phase transition occur above 900℃.
Phosphorus doped TiO2 sample heated at 500℃ shows the best photocatalytic activity in MB degradation. Electron Paramagnetic Resonance (EPR) studies at 77K on phosphorus doped TiO2 nanoparticles show enhanced hole signal intensity for the sample heated at 500℃, which is due to enhanced charge separation. Based on EPR results in combination with XRD, XPS, UV-vis and Raman studies, enhanced charge separation is found to be the reason for the enhanced photocatalytic activity.
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