Preparation and Characterization of Visible-Light-Driven Photocatalytic Powders and Thin Films
|關鍵字:||可見光;光觸媒;鈣鈦礦相;二氧化鈦;薄膜;高壓水熱;visible light;photocatalyst;perovskite;titania;thin films;high pressure||公開日期:||2006||摘要:||本論文採用溶膠-凝膠法製備BaCo0.5Ta0.5O3粉體。在經過800 oC的鍛燒後，可得到BaCo0.5Ta0.5O3之單相粉體。從紫外光-可見光吸收光譜中可以看出該粉體具有較寬廣的能隙，而從光反應實驗中可知該結構擁有紫外光光觸媒活性。將銀金屬以含浸法負載於此粉體表面後可使其展現出較為優良的光反應性。
BaCo0.5Ta0.5O3 powders were prepared via a sol-gel method. The monophasic perovskite phase was formed after calcining at 800oC. From the UV-vis spectra, this compound revealed a wide band gap and exhibited photocatalytic activity under UV light irriadiation. The photo-activity was improved through loading of silver metal on the surface of BaCo0.5Ta0.5O3 particles. A new type of photocatalyst-BaCo0.5Nb0.5O3 was successfully synthesized by a sol-gel process. After heating at 1000oC, the pure phase of this compound was formed. The particle size and the crystallinity of BaCo0.5Nb0.5O3 powders significantly depended on the calcining temperature. The band gap calculated from the UV-visible spectra was narrower than that of titania. BaCo0.5Nb0.5O3 was demonstrated to have photocatalytic activity under visible light irradiation. The photo-activity of the prepared BaCo0.5Nb0.5O3 powders significantly depended on the synthesis temperature. The 1000oC-calcined powders were found to have the highest photocatalytic activity because of their well-crystallized structure and uniform particle size. In the final part of this thesis, iron-ion doped titania powders were prepared. The XRD result showed that doping iron-ion can promote the phase transformation from anatase to rutile phase. In the UV-vis spectra, the modified Fe3+-doped TiO2 shifted the absorption edge of TiO2 to the visible light region. The relation between the doping content of iron-ion and photocatalytic activity was discussed. Iron-ion doped titania thin films, responding to visible-light irradiation, were successfully synthesized via the high-pressure crystallization (HPC) process. The monophasic anatase of TiO2 was formed at a temperature as low as 125oC under the high-pressure process. The doping content of iron-ion in TiO2 films significantly influenced the photo-activity. The particle sizes of the films were enlarged with a rise in the annealing temperatures. The Fe3+-doped TiO2 thin films prepared via the HPC had uniform surface structure. In comparison with the films prepared via the conventional annealing process, the HPC-derived films have better photo-activity.
在 IR 系統中的文件，除了特別指名其著作權條款之外，均受到著作權保護，並且保留所有的權利。