Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Characterization of One-Dimensional Functional Metal Oxide Nanomaterials

Author ZhuYiNa
Tutor WangRuZuo
School Tsinghua University
Course Chemistry
Keywords two-phase system dynamics controlling nanowirescomposite nanomaterials
Type Master's thesis
Year 2011
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Owing to the unique dimensional-structure and chemical/physical properties,one-dimensional (1D) nanomaterials have exhibited potential applications in the fieldof catalysis, batteries, photoelectricity, sensing and magnetics. And investigating theproperties and applications should carry out on the basis of material preparation.Therefore, to precisely control of their dimensionalities, morphologies and sizes mayserve as an important role for understanding the relationship between structures andcorresponding properties then tailoring the properties in a controllable form. In thisdissertation, exploratory research have conducted on the new solution-based syntheticstrategies of1D metal oxides nanomaterials and new types of organization patternsfor composite nanomaterials as well as their fabrication mechanism.An indirect transformation approach has been developed to obtain1D Co3O4nanomaterials from pre-synthesized basic cobalt carbonate. Upon the anisotropicstructure of it, a control method based on dynamics assisted with a two-phase systemwas designed to synthesize nanowires of basic cobalt carbonate. The coordination ofCo2+and oleyl amine leaded a stable cobalt source; The interface because of theinsolubility of Co2+-oleyl amine in water was favorable for oriented growth ofnanocrystals; The selective absorption of oleyl amine molecule on different faces ofcrystal inhibited the growth of nanocrystals except along axial direction and avoidoriented attachment between nanowires. In addition, a solvothermal route was used toget nanowhiskers of basic cobalt carbonate, which was to demonstrate the nucleusgrowth mechanism of nanocrystals without introduction of any surfactant.Taking the as-prepared nanowires of basic cobalt carbonate as building blocks, astrategy based heterepitaxial growth and diffusion was developed for synthesizingSnO2/Co(OH)x+2ε(CO3y-εcomposite nanotubes, with tunable atomic Sn/Co ratio andwall thickness. The formation mechanism was also detailed investigated. Comparingto the traditional core/shell heterepitaxial growth or homo-doping, this organizationpattern made a uniform distribution of different components in a whole tube, and they could exist in a relatively high content within a limited extent. Besides, promotingthis mechanism could also be used to fabricate TiO2/Co(OH)x+2ε(CO3y-ε.Because the crystal characteristics of asymmetric oriented growth, it could bepredicted that ZnO tend to follow a1D growth mode. Based on systematic theoreticalanalysis, a series tactics were devised to simplify experimental procedures, a systemcomposed of PVP/H2O was used to research the controllable synthesis of ZnOnanostructures and their growth mechanism. The two-phase means developed abovewas also make used to synthesize high length-diameter ratio and quasi-monodispersedZnO nanowires.

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