Synthesis Of Metal Oxide Dielectric Holes And Nano-composite Materials

Metal oxides are largely studied because of their almost limitless potential in a number of industrial applications. Among metal oxides alumina and titania are.very popular for their unique properties and diverse applications. Alumina has numerous applications ranging from catalysis, to optics, electronics and biomedicine. Titania is a chemically stable, non-toxic and environmentally friendly oxide and it has been intensely investigated in photocatalysis and dye-sensitized solar cell and so on.With the characteristics of mesoporous materials, such as highly uniform channels, large surface area, narrow pore-size distribution, tunable pore sizes over a wide range, and so on, metal oxides with a mesostructure should possess much more excellent properties for their applications.In this thesis, we studied the synthesis of ordered mesoporous alumina, mesoporous alumina-titania and gold nanoparticles/titania composites.In chapter 2, we use inorganic aluminum salt and aluminum alkoxides as precursor to synthesize highly ordered mesoporous alumina by "acid-base pair" method through the evaporation-induced self-assembly (EISA) process. By changing experiment parameter such as mol ratio of precursors, different precursors and surfactants, we successfully get mesoporous alumina with a highly ordered 2D hexagonal mesostructure, high surface area(31 1m2/g, Al(NO3)3:AlPO=5:5), large pore volume and pore size(11.5nm, AlC13:AlPO=5:5), which is resistant to high temperature up to 800℃.In chapter 3, mesoporous alumina-titania composite are synthesized by "acid-base pair" method through the evaporation-induced self-assembly (EISA) process. The effect of the mol ratio of the "acid-base pair" and EISA temperature are investigated on the mesostructures and crystalline. The series of composites have worm-like mesostructures, uniform pore size distribution(6～11nm) and higher surface area(244 m2/g) compared with pure mesoporous titania. It is found that the crystallization temperature of alumina decreases in the mesoporous alumina-titania composites(700℃). while the crystallization and crystalline transformation temperature of titania increase(>400℃and (900℃). which indicating that the thermal stability of titania is improved.In chapter 4, spherical gold nanoparticles with diameters less than 8 nm have been prepared by the photoinduced reduction via a one-step sol-gel process. The Au nanoparticles are highly dispersed in a TiO2 gel monolith with a surface plasmon resonance absorption band centered at 578 nm.. We demonstrated for the first time that the photoinduced reduction of AuCl4- ions in the sol stage instead of after the gel formation could guarantee the uniformity of the size(8nm), shape, and dispersion of Au nanoparticles in the ultimately formed TiO2 gel.