Studies on Group VA Elements Doped TiO2 as Photocatalysts Using Visible Light

• Main Authors: Cheng-Chao Yang, 楊政晁
• Other Authors: 鄭淑芬
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/98762500085769500833

博士 === 國立臺灣大學 === 化學研究所 === 97 === The synthesis methods of coprecipitation and deposition-precipitation were used in this thesis. The elements of P, Sb, and Bi were doped in titanium dioxide for application as photocatalyst to degrade organic pollutants. The phosphoric acid, antimony(III) chloride and bismuth nitrate were as source of P, Sb, and Bi and diluted or solved in acid, respectively. The solution was mixed with 4M TiOCl2 and refluxed together to get doped titanium dioxide. The crystal phase of titanium dioxide was affected by the dopants. The phase was changed from pure rutile to become mixed phase (anatase and rutile) if more dopant was added. The best photocatalyst is as-made Bi-doped titanium dioxide and mole ratio is 10~12% when phenol solution was photocatalyzed by doped titanium dioxide by 419nm wavelength light source. In addition, photocatalytic activity of Bi-doped TiO2 is better than commercial Degussa P25. But, the photocatalytic activity of Bi-doped titanium dioxide is less than Degussa P25 when used to degrade benzaldehyde solution. The particle size of catalyst may be larger and causes photocatalytic activity gradually decreased when treated at higher temperature. The pH effect is also an effect factor of photocatalytic activity. The photocatalytic degradation of phenol solution is helpful in acidity, but benzaldehyde is not affected by this factor. For deposition-precipitation method, the rutile and anatase phase of titanium dioxide must be made before bismuth loaded on the surface. Then, bismuth solution was added and pH adjusted between 6 and 7 by 1M sodium hydroxide solution. From the patterns of XRD, all of the catalysts are single phase, that is, the dispersion of bismuth on the surface of TiO2 is homogenerous. After Bi loaded, the UV-Vis spectra showed a shoulder between 400nm and 600nm. The absorption spectra of loaded P25 had clearly red-shift. The results of degradation of phenol solution, 1% mole ratio bismuth precipitated on rutile phase titanium dioxide which photocatalytic activity and mineralization ability are better than loaded P25 and anatase TiO2. In addition, the 1% bismuth loaed TiO2.had best photocatalytic activity when treated at 200℃ for 2 hours. Using the characteristic of high specific surface area of mesoporous materials to adsorb organic pollutants in order to increase organic pollutants degraded ratio. The Bi-doped TiO2 was supported on MCM-41 and SBA-15. The samples were measured IR, specific surface area, XRD, TEM and photocatalytic activity.