| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 98 === In this study, the gold-loaded titanium dioxide was prepared by photodeposition and impregnation methods for the better activity. The gold nanoparticles can capture the photoexcited electron of titanium dioxide to reduce the recombination rate of electron and hole.
In this research, the effects of content of gold, particle size of gold, particle size of titanium dioxide, and preparation methods on surface plasmon resonance (SPR) phenomenon and the photocatalytic efficiency are investigated in detail. The transmission electron microscopy (TEM) , X-ray diffraction (XRD), UV-Visible-diffuse reflectance spectra (UV-VIS-DRS), X-ray photoelectron spectra (XPS), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and photoluminescence (PL) spectroscopy were applied to observe the morphology, crystal structure, light absorption, surface composition, gold content, and emission from the recombination of photoexcited electron and hole, respectively. The photocatalytic activity was evaluated by the decolorisation of methyl orange solution over the modified titania under illuminations of UV-A and UV-A/GLED.
The PL intensity decrease greatly with the presence of Au on TiO2 due to the electrons will be trapped by gold nanoparticles, resulting in the improvement of photocatalytic activity. The Au-TiO2 will have an absorption peak (530-570 nm) due to the surface plasma resonance effect. The SPR absorption increases with the increase of gold content. The results of photocatalytic experiments indicate the UV-photocatalytic reaction rate will be enhanced by using the illumination of green light simultaneously. The strong electric field, resulting from the surface plasma resonance excitation, is generated as Au-TiO2 is irradiated by green light. It then improves the generation rate of photoexcited electron and hole of titanium dioxide under UV irradiation. Therefore, the photoactivity of Au-TiO2 in the double beam system (UV/GLED) is better than that in single beam system (UV). The SPR phenomenon is affected by particle size of gold and TiO2, amount of gold, and coherence properties between TiO2 and Au. The experiment results show that synergistic effect between UV and green light for the improvement of photoactivity will be increased by increasing the SPR-absorption of Au-TiO2 and adjusting the wavelength of SPR to the green-light region.
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