| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 102 === In this study, we have demonstrated that length-tunable copper nanowires and nanotubes were successfully produced by using the anodic aluminum oxide (AAO) nanotemplate combined with the electrodeposition process. As the result, the wall thickness of nano tube with a gradient variations. Field emission measurements showed daturn-on fields of Co nanowire and nanotube are 1.75 V/μm and 2.43 V/μm, respectively. Moreover, the field enhancement factor(β) of Co nanowires was found to be larger than that of Co nanotubes, the result might be attributed to the so-called screen effect.
In this study, the cobalt nanowires were treated with different thermal oxidation time under oxygen atmosphere at 450℃ and 350℃.Finally, it became bead-like nanotube with kirkendall effect. We study the morphology、crystal structure and formation mechanism of Co wire during thermal oxidation with TEM. In this observation, we can tell that the sequence of the appeared cobalt oxide phase is from CoO to Co3O4, and the CoO generated at the close to the Co , and the site of Co3O4 is outside the CoO.
In this work , we fabricated the large-area Co3O4 nanowire by air oxidation of Co film .The possible mechanisms of the growth of nanowires are discussed in the context of the stress relaxation from the oxidation layer. In addition, the surface-wetting properties of the Co3O4 nanowires were evaluated by water contact angle measurements. We found that the wetting behaviors changed from hydrophilic to hydrophobic by vacuum annealing 、 placed under a vacuum environment or atmospheric environment. We speculate that this phenomenon is related to the desorption of surface oxygen atoms.
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