| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === In this experiment, CuO-V2O5 heterogeneous nanostructures was synthesized by a two-stages chemical process where V2O5 nanowires were synthesized by using a hydrothermal method in the first stage, and then CuO nanoparticles were decorated on the surface of V2O5 nanowires through wet-chemical reaction in the second stage. The morphologies. compositions, and crystalline structures of the as-synthesized products were characterized by SEM, XRD, and TEM. To study the growth mechanism of V2O5 nanowires, the synthesis process was terminated at different growth times and the corresponding morphologies and structures were examined. Gas sensors based on V2O5 nanowires and CuO-V2O5 heterogeneous nanostructures were fabricated to investigate their gas sensing properties to CO and NO2 gases.
The experimental results show that the growth mechanism of V2O5 nanowires is deduced to be the oriented attachment (OA) mechanism. The V2O5 nanoparticles will first nucleate in the precursor solution and then grow into nanorods. In the meantime, the growing nanorods will rotate each other to find the orientation with the lowest surface energy and attach together to from V2O5 nanowires oriented along the [110] direction. At the aspect of gas sensing properties, the gas sensitivities of the V2O5 nanowires can be enhanced as the operation temperature is increase due to the thermal activation effect. The CuO-V2O5 heterogeneous nanostructures have a better gas sensing performance than the bare V2O5 nanowires because of their larger surface-to-volume ratios and the existence of extra p-n junctions.
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