Controlled Synthesis And Photocatalytic Properties Of Semiconductor Metal Oxide Nanomaterials

In recent years, by the continuous development of the economy and theimprovement of people’s living standard, environmental problems haveattracted more and more attention in China. With the rapid development of theresidence decoration complexity, the indoor air pollution problems have beengrowing. People begin to pay high attention to the indoor air quality (IAQ)problems. Common volatile organic compounds (VOCs) emitted fromfurniture and building materials are the main pollutants which lower theindoor air quality. Photocatalytic technique is one of the most economical andefficient approaches to eliminate volatile organic compounds. Semiconductormetal oxides are believed to be the most promising materials forphotocatalytic applications.Owing to their variety of electronic structures and alterable valencestates, semiconductor metal oxides exhibit diversified physical and chemicalproperties, and have shown many applications in catalysis, solar cells and gassensors. In order to achieve the insight view of the structure-propertyrelationship, it is essential to develop simple and controllable syntheticmethods towards metal oxide nanomaterials with particular phases, sizes andmorphologies. In this dissertation, systematic explorations have been carriedout on the synthesis of some semiconductor metal oxides nanostructures suchas SnO2and TiO2. Their application on elimination of indoor air pollutionsand more detailed analysis on the relationship between the materials’structures and their photocatalytic properties have also been investigated.Based on Liquid-Solid-Solution (LSS) phase transfer and seperationmethod, various SnO2nanostructures with controllable sizes and shapes havebeen successfully prepared. The morphologies of the SnO2nanostructurescould be rationally tuned via adjusting the hydrolysis degree of Sn (IV) ionsby the pH of the reactant solution. A series of SnO2photocatalysts with different size distributions have been obtained by controllable calcination ofthe as-synthesized SnO2nanocrystals. The as-obtained SnO2photocatalystsexhibit good photocatalytic reaction activity towards volatile organiccompounds and show strongly size-dependent photocatalytic properties.Detailed studies based on the kinetic analysis of the photocatalytic processhave proven that the good photocatalytic performance is owing to the rising ofBET surface areas of our SnO2nanocrystals brought by the decreasing of theirsizes.TiO2nanocrystals have been prepared based on a solution chemistrypathway. The as-obtained nanocrystals can be organized into mesoporousTiO2colloidal nanospheres by Emulsion-based Bottom-up Self-assembly (EBS)method. The photocatalytic properties of the as-prepared TiO2colloidalnanospheres have also been investigated.