Shape and Size Control of Cu and Cu/Ag Composite Nanostructures by Electrochemical Methods for Biosensing Applications
| Autor: | Chia-Jung Yang, 楊家榮 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 This study focuses on the shape and size control of Cu nanoparticles by tailoring the surface morphologies of TiN thin film electrode. These Cu nanoparticles were further used to fabricate Cu/Ag composite nanostructures. TiN thin films exhibiting superior electrical and thermal conductivity, high chemical stability and hardness are of technologically important materials. The surface morphologies of TiN thin films can be varied by changing the deposition parameters during sputtering. The novelty of this research is using the surface morphologies of TiN thin films to control shape and size of Cu nanoparticles. This model system can be extended to other conductivity nitride thin films. In contrast, conventional shape and size control of metallic nanoparticles, such as variation of electrolytes and power mode was also used. The sputtering deposition parameters including the power and working pressure were varied to prepare TiN films. In this study, we obtained granular TiN films at a higher sputtering power and a lower working pressure while pyramidal TiN films at a lower sputtering power and a higher working pressure. Under the same electrodeposition conditions, smaller irregular Cu nanoparticles formed on a pyramidal TiN film and larger, octahedral Cu nanoparticles grew on a granular TiN film. In comparision, the species and concentrations of the surfactant, salts as the stabilizer, and the power mode were also varied in synthesizing Cu nanoparticles. The significant effect of the concentration of surfactant was confirmed. It contributed to the growth of the smaller, irregular Cu nanoparticles when the concentration of surfactant was higher than their critical micelle concentration (CMC). As the concentration of surfactant was lower than the CMC, cubic Cu nanoparticles were formed. Another objective for this study is to investigate the electrocatalytic abilities of Cu nanoparticles with various shapes and sizes for nonenzymatic glucose sensing. This has not been reported before. The sensitivity of the smaller, irregular Cu nanoparticles in the detection of glucose was better than that of the larger, octahedral Cu nanoparticles because of the former’s greater increase in the Cu2+-to-Cu0 ratio. We also used various sizes of Cu nanoparticles as starting materials to prepare the Cu/Ag composite nanostructures via galvanic displacement reaction. Cu/Ag core-shell structures were formed by using smaller Cu nanoparticles as the starting materials, while Cu nanoparticles/Ag nanobelts structres were made by using larger Cu nanoparticles as the starting materials. Both structures revealed the surface-enhanced Raman scattering phenomenon with Rhodamine 6G (R6G) as the probe molecule. Tailoring simply the surface morphologies of TiN thin films can control shape and size of Cu nanoparticles during electrodeposition. Different Cu/Ag composite nanostructures can be formed with various sizes of Cu nanoparticles by galvanic displacement reactions. Various shapes and sizes of Cu nanoparticles and those of Cu/Ag composite nanostructues revealed pretty good biosensing ability. This technique may be extended to other nitride thin film systems, which has great industrial applications. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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