Synthesis Of ZnO, MnO₂, Silica Nanostructures And Their Physical And Chemical Properties

Oxide nanomaterials have extensive potential application in many field, such as luminescence, photoelectronic, chemical sensor, catalyst, biomedical, electrochemical energy storage and others, due to their unique physical and chemical properties. In this dissertation, three kinds of oxide nanostructure materials which are silica, ZnO and MnO2 were synthesized through vapor-phase process and liqiud-phase process, and their physical and chemical properties were investigated, which could be summarized as following:1. Bud-like, brushhead-like and feather-like silica nanostructures were synthesized via vapor-phase process. It was found that the silica nanowires epitaxially grow from the silical shell coating on metal Ga partical by vapor-solid mechanism. The difference of defects type and number in silica nanowires with different morphologies cause the difference of their photoluminescence.2. ZnO nanocombs were synthesized via vapor-phase process. ZnO nanorods quasi-array and ZnO nanoparticles grown on the up and down side of one silicon substrate were also synthesized via vapor-phase process. The annealing effect in different atmospheres on morpholoy, microstructure and photoluminescence of the ZnO namocombs was studied. The photoluminescence and superphdrophobic properties of ZnO nanorods quasi-array and ZnO nanoparticles and their microstructures were studied, and the mechanism for the difference of their properties was discovered.3. Carbon nanotubes were dispersed in solution by the electrostatic repulsion between the negtive charged poly(4-styrenesulfonic acid) (PSS) moleculars, and the electrostatic attraction between PSS molecular and Mn2+ causes the MnO2 nanoparticles depositing on the surface of carbon nanotubes/polyaniline coaxial struture to form carbon nanotubes/polyaniline/MnO2 ternary coaxial materials for supercapacitor. The surface to volume ratio of MnO2 in this composite electrode material was increased considerablly, and the electronic conductivity and the electrochemical utilization of MnO2 were increased too.4. The MnO2 nanoparticles/carbon nanotubes composite mateirals for supercapacitor were synthesized in solution condition, and the electrochemical properties of this electrode material was investigated. In order to discover the effect of charge/discharge process on the morphology, structure and electrochemical properties of this composite, several electrodes with this material were charge/discharged 500 cycles at different potential scan rates.