UC Riverside

The controllable synthesis of colloidal titanium dioxide nanomaterials can yield materials with tunable properties and morphologies. The crystal grain size in nanoscale TiO2 has been determined to be of importance to the photocatalytic activity and in my work the synthesis of anatase titania microspheres with controllable grain sizes was obtained by impregnating the porous networks of amorphous titania microspheres with silicate oligomers and calcining the composite. Controlling the degree of silicate impregnation enables the tuning of the grain size and surface area which yields and optimal sample for photocatalysis.

The optimization of coating TiO2 onto nanoparticles and microspheres was next explored to create a simplified system which can easily coat a wide range of particles. The system consists of a mixed solution of titanium n-butoxide and ethylene glycol to create a titanium-glycolate precursor which can directly coat spherical and anisotropic metal nanoparticles as well as on larger particles such as SiO2 and polymer microspheres through an extension of this method. Further, the thickness of these coatings can be tuned and this coating can be crystallized into TiO2 through refluxing in water for low crystallinity or calcination to obtain highly crystalline shells.

The titanium glycolate coating method can also incorporate additional metals into the precursor mixture to obtain a doped TiO2 shell which can extend the light absorption into the visible range. Additionally, a study of the effect of the metal dopant on the crystalline grain size of the obtained product has been done as well. An increase or decrease in grain size relative to pure TiO2 can be predicted by if the metal typically promotes or inhibits the anatase to rutile phase transition.

Hollow, metal incorporated TiO2 can be produced by utilizing a sodium titanate intermediate which readily ion exchanges with target metals. This incorporation of metals can yield doped TiO2 products with improved photocatalytic capabilities. Additionally, Fe3+ incorporated materials can be reduced to form a porous and magnetic iron oxide-TiO2 composite structure. This combination of properties allows for the composite to be applied to the separation of phosphorylated proteins from a protein mixture.