Synthesis And Application Of Oxide Nanoparticles And Their Composites

Nanooxides and their composites are important materials showing promising potentials in reinforcement and functionalization of classic materials, drug targeted delivery, separation, purification, biosensors and so on. Oxide nanocomposites possess not only the combination of the functions inherited from its contents but also novel properties resulting from the synergism among them. Developing new methods for synthesizing different nanoparticles, controlling the assembly process for periodical regular structure searching for novel functionality and even designating functional device, studying the factors affecting their mesostructure and the relationship between property and structure should be beneficial for theoretical investigation as well as the application of the oxide nanomaterials and their composites.Following the methodology above, this dissertation presents a systematic research on the relationship among the synthesis, structure, property and application for several oxide nanoparticles and their composites. The main results were summarized as follows:Chapter 2:A core-shell hybrid nonocomposite composed of silica and polydimethylsilane (PDMS) was successful synthesized by a novel solvent adjustment strategy through the direct reaction between silica nanoparticles and PDMS by using cheap commercial aqueous silica sol. The nonocomposite was characterized and a possible mechanism was discussed. A preliminary application for the nanocomposites in coating material was carried out which revealed obvious improvement in the property of the coating film.Chapter 3:Two kinds of flower-like zinc oxide nanocrystals were synthesized by mixing KOH and ZnCl2 in glycerol solution. The experimental parameters affecting the formation of the nanocrystals were optimized, and possible mechanism was discussed. The obtained products were characterized with XRD, SEM techniques and UV-Vis spectroscopy. The results indicated that the flower-like nanocrystals were hexagonal wurtzite structure. In addition, hemoglobin (Hb) was immobilized on the ZnO nanocrystals. It was found that the flower-like ZnO could enhance the direct electron transfer of Hb. The results showed that the as-fabricated biosensor had a good linear amperometric response to H2O2 in the concentration range from 1×10-6 to 1.2×10-4 mol L-1.Chapter 4:The core-shell type ZnO nanosphere/CdS nanorod and ZnO nanosphere/CdS nanoparticle composites have been selectively prepared through a simple ultrasound-assisted solution phase conversion process。using monodispersed ZnO nanospheres as a starting reactant and in situ template. The formation mechanism of the products is closely connected with the ultrasonic effect. The photoluminescence and electrogenerated chemiluminescence properties of the as-prepared core-shell structures were investigated.Chapter 5:By using hexamethylenetetramine and sodium citrate as the reaction, morphology and assembly control agents, a well dispersed hollow hexagonal ring-shaped structure of ZnO/Au nanocomposite was successfully fabricated through microwave assistant hydrothermal method. The composite is composed of layered ZnO and randomly scattered Au nanoparticles on the surface. The composite was characterized by XRD, SEM, TEM. Its optical properties were investigated according to UV and PL spectra and a possible mechanism of the formation for the as prepared composite was proposed.