Mesoporous titania molecular-sieve thin films have been modified by incorporating guest species either in the pores or on the walls of the structure. The incorporation was realized with the aid of sonochemical processing. The structure, morphology, texture, optical properties, and stability of the resulting nanostructures were characterized by X-ray diffraction, nitrogen adsorption, UV-vis diffuse reflectance spectroscopy, infrared spectroscopy, photoluminesent spectroscopy, scanning electron microscopy, transmission electron microscopy, thermalgravimetric and differential thermal analyses. The photocatalytic and catalytic properties of the mesoporous TiO2-based nanocomposites were evaluated by photocatalytic degradation of organic pollutants, photo-assisted killing of bacteria/cancer-cells, and catalytic oxidation of carbon monoxide. / The thesis includes seven parts. The first part describes the pore-wall chemistry and photocatalytic activity of mesoporous nanocrystalline TiO 2 molecular sieve films. The ordered mesoporous TiO2 films show better photocatalytic activities than do the conventional sol-gel-derived TiO2 films toward the degradation of volatile organic pollutants. The reasons for the high activities of the mesostructural films are also discussed. The second part of the thesis reports the incorporation of highly dispersed gold nanoparticles in the mesoporous TiO2 films by a sono- and photochemical approach. The gold nanoparticles thus obtained are well-confined and stabilized in the nanopores of the TiO2 film and therefore, the intrinsic agglomeration of gold nanoparticles is prevented. This eliminates the use of potentially catalyst-poisoning organic ligands for stabilization. This method can also be used to prepare ordered mesoporous Pt/TiO2 and Ag/TiO2 nanocomposites with catalytic and photocatalytic functions as described in the third and forth parts of the thesis. In the fifth part, solid superacid molecular sieves are prepared by the wall-functionalization of the TiO2 film by sulfate groups with the aid of sonication. The resulting 3D-ordered mesoporous sulfated TiO2 superacid molecular sieve films are found to be attractive photocatalysts for environmental applications. The sixth part the thesis reported the sonodeposition of poorly dissolved phthalocyanine dyes onto the surface of the TiO2 film. The dye molecules are attached and stabilized in the pores of the film, avoiding the aggregation of the dye molecules, and consequently achieving effective photosensitization of the TiO2 film. The final part of the thesis describes the preparation of hierarchically macro/mesoporous TiO2 nanostructural photocatalysts. The existence of macroporous channels in a mesoporous TiO2 material improves the photoabsorption efficiency and matter-transfer. These enhance the photocatalytic performance of the bimodal porous TiO2 nanocomposites toward degradation organic pollutants in gas-phase. (Abstract shortened by UMI.) / Wang Xinchen. / "July 2005." / Adviser: Jimmy C. Yu. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0293. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_343610 |
| Date | January 2005 |
| Contributors | Wang, Xinchen., Chinese University of Hong Kong Graduate School. Division of Environmental Science. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xxi, 215 p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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