| Summary: | 博士 === 國立清華大學 === 化學工程學系 === 102 === In this dissertation, we have three themes.
First : Shape control and properties analysis of Cu nanomaterials. Cu nanowires and Cu nanocubes can be synthesized in solution phase by using CuCl as precursors with right surface ligands. Electron microscopy and UV-vis spectra were used to track the growth process of Cu nanowire and further proposed possible growth mechanism. In addition, the electrical property of single Cu nanowire and surface-enhanced Raman spectroscopy of Cu nanowire substrate had studied. The as-synthesized Cu nanocubes have a slightly truncated with an average edge length of 75.7 nm and a standard deviation of 3.87 %. Electron microscopy and Small-angle X-ray scattering characterizations were used to identify the self-assembled structures of Cu nanocubes. Based on analysis results, Cu nanocubes prefer self-assemble into 2D or 3D rhombohedral structure. Cu thin films composed of monodisperse Cu nanocubes were made by tilting the substrate in the Cu nanocube solution and controlled evaporation rate of toluene. Furthermore, the electrical properties of Cu thin films were also studied before and after thermal annealing.
Second : Shape control and properties analysis of Cu2−xTe nanomaterials. Solid and hollow structures of Cu2−xTe nanocrystals can be synthesized by injection of a Te-TOP solution at different injection time. Both types of Cu2−xTe nanostructures exhibit an intense absorption peak (localized surface plasmon resonance, LSPR) in the NIR region, arising from excess holes in the valence band, with high molar extinction coefficients of 2.6 × 107 M−1 cm−1 at 1150 nm and 2.7 × 107 M−1 cm−1 at 1200 nm for the solid-type and hollow-type Cu2−xTe nanostructures, respectively. The LSPs band of the Cu2−xTe nanostructures can be fine tuned by post processing via oxidation and reduction methods (controlling their degree of copper deficiency).
Third : Si(Ge)/Cu free standing nanowire fabric for lithium ion battery anodes. Si (Ge) based free standing nanowire fabric electrodes which are made by Si (Ge) nanowires with high theoretical capacity and Cu nanowires with high electric conductivity can be directly used as lithium ion battery anode electrodes. These special electrode structure have advantages of lighter weight than conventional electrodes fabricated by slurry process, good electron transfer offered by the Cu and the one dimensional nanostructure, and the space among the nanowires accommodating the volume contraction of Si (Ge) nanowires during alloying and dealloying process. In addition, the effect of the weight percentage of Cu nanowire and annealing temperature on the electrochemical performance had investigated.
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