Preparation And Catalytic Characterization Of TiO2Composite Nanospheres Based On Sol-Gel Method

Because of its unique photo physical and photochemical properties,Nano-titanium dioxide, which has aroused great interest, has a wide range ofapplication prospects in optical materials, photoelectron chemical, photovoltaic cellsand photo catalytic degradation of organic compounds. In the nature, titania mainlycontains three crystal configuration, namely the anatase, rutile and brookite.Nano-titanium dioxide particle size is1to100nm belong to the scope of themesoscopic, having more excellent physical and chemical properties thanconventional materials, such as quantum size effect, small size effect, surface effectand macroscopic quantum tunneling effect which gives nano-titanium dioxide a broaduse. The most important property of Titania is the photocatalysis, but it will fall topieces and decompose into smaller particles in the photo catalytic process, resulting ina difficulty in recycling and gathering. There is a great influence on Titania’s catalyticactivity. It largely limits its application in reality.In this study, two parts of work had been completed: in the second chapter, wefirst prepared amorphous TiO₂nanoparticles with a regular morphology by sol–gelmethod, and then modified a silane coupling agent layer with a double bond on itssurface. Finally, the polystyrene-coated TiO₂core-shell nano microspheres aresynthesized by the polymer dispersion polymerization method. In order to achieveanatase TiO₂, TiO₂@PS nano microspheres are carbonized in the conditions of800℃high temperature under nitrogen protection, one-step to achieve both TiO₂microspheres transition from amorphous to anatase, and the outer layer from PS shellto carbon. We are looking forward to the presence of stable carbon shell to preventTiO₂nanoparticles from breaking down into tiny particles in the TiO₂catalyticprocess, thus improving the photo catalytic stability of the nanoparticles. Finally, we characterized the photo catalytic properties of the prepared TiO₂@PS nanocompositemicrospheres.In the second chapter, in order to solve the defects of nano-TiO₂recovery, weadded pre-synthesized Fe3O4nanoparticles to the TiO₂precursor, synthesizedFe3O4@TiO₂composite nanoparticles by sol-gel method; we explored their synthesisroute and optimal feed ratio, TiO₂shell was changes amorphous to anatase phase byhydrothermal in not high temperature. Finally, we studied the photo catalyticproperties of Fe3O4@TiO₂nanoparticles and recycled them with magnets, then makethe secondary loop catalytic experiments. In the end the recycled Fe3O4@TiO₂nanoparticles still showed a high efficiency for methylene blue dye degradation.