| Summary: | 博士 === 國立中興大學 === 化學工程學系所 === 102 === Abstract
Titanium oxide (TiO2) is the most popular photocatalyst. However, the TiO2 application is restricted in the ultraviolet light (UV) irradiation. Thus, researchers are dedicated to improve the photocatalytic activity of TiO2 for the visible light application.
The purpose isof this study to synthsize the visible light responsive photocatalyst, and has been classified into three parts. In the first part, TiO2 thin films were prepared by the sol-gel method employing polyethylene glycol 1000 (PEG 1000) as an organic template. Pore sizes were adjusted by varying the concentration of PEG 1000. The optimal PEG concentration range required to form TiO2 films with a regular porous structure was investigated and was found to be 0.01–0.015 M. The results showed that the photocatalytic activity was correlated to the porous size and porous density. The TiO2 thin films possessing pore sizes in the diameter range of 35–85 nm exhibited the best conversion of 98% after 8 h of UV irradiation
In the second part, TiO2 particles are well coated on the multi-wall carbon nanotubes (MWCNT) by the directhydrolysis method. The results have been demonstratedthat MWCNT can enhance the photocatalytic activity by reducing the recombination of electron-hole pairs. The degradation of methyl orange can reach 80.0% under the UV light irradiation for 1h. There is no degradation under the visible light irradiation.
In the third part, silver bromide is added into the composite catalyst of TiO2/MWCNT by the precipitation method. The synthesized catalyst of Ag/AgBr/TiO2/MWCNT reveals the good responsive ability to visble light. The optimal synthesized parameters of catalyst in the process have been determined. The optinal amount of MWCNT is 1 wt%, and the suitable molar ratio of Ag/Ti is 10%, and the best calcined temperature is 400oC. The degradation of methyl orange can reach 82.3% under the visible light irradiation for 1h
In the forth part, the catalysts of Ag/AgBr/TiO2composite catalysts treating at hightemperature of 500oC, causing the catalysts have a smaller surface area. In order to increase the surface area, the suitable type of dispersant, the concentration of dispersnt, and the optimal synthesized pH value are determined. The Ag/AgBr/TiO2 synthesized in the pH11 solution with 0.1 M of cetyl trimethylammonium bromide (CTAB) has the best photocatalytic activity. The degradation of methyl orange can reach 89.0% under the visible light irradiation for 1h.
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