| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 103 === This thesis focuses on the preparation of electrospun carbon nanofibers and their composites as supercapacitor electrodes, which involves three parts. In the first part, nanostructural carbon nanofibers are prepared through electrospinning using polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) as precursors. We investigate the effect of PMMA molecular weight on the morphology and electrochemical performance of the nanofibers. During pyrolysis, PMMA decomposition causes the nanofibers to develop from a porous structure into a hollow structure with increased PMMA molecular weight. Additionally, the removal of PMMA increases substantially the specific surface area and the pore volume of the carbon nanofibers, which results in a specific capacitance of 210 F/g and favorable cycling stability with a retention ratio of almost 100% after 2000 cycles. In the second part, we perform surface modification on electrospun carbon nanofibers using oxygen plasma and nitric acid oxidation. Both methods incorporate various oxygen functionalities, mainly carbonyl groups, onto the carbon surface, resulting in the change of fiber wettability from hydrophobic to hydrophilic. The specific capacitance of the modified carbon nanofibers is 377.0 and 365.4 F/g for oxygen plasma- and nitric acid-treated nanofibers, respectively. In the third part, we prepare Ni(OH)2/carbon nanofiber composites and study the morphological progress and the subsequent electrochemical performance of the composite fibers. Electrochemical measurements reveal that the specific capacity of the Ni(OH)2/carbon nanofiber composites increases with an increase in the annealing temperature and reaches a maximum of 455.0 C/g at 300 oC.
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