| Summary: | 碩士 === 中國文化大學 === 材料科學與奈米科技研究所 === 94 === This thesis investigated the effect of the density control of carbon nanotubes (CNTS) and the deposition methods of ruthenium oxide on the capacitive performance of electrochemical super-capacitor. The research provides the experimental results of the high surface area utilization of CNTS and the influence of electrode nano-particle deposition methods on the efficiency of electrolytic reaction
The density of CNTS was altered by varying the catalysis concentration of alloy and the ratio of covered area on catalysis-metal surface. The value of capacitance changed with the ratio of iron-silicon bimetal area, and a value of 42.3mF/cm2 can be achieved at the ratio of 3:1. The influence of the density and the alignments of CNTS on the effective surface area for the electrode particle plating were discussed as well as the capacitive performance.
The deposition of electrode particles by the method of electrochemical plating was also studied. It was found that suitable annealing temperature enhanced the crystallization of the electrode material, which provides a better condition for ion-electron transport. Both capacitance and current density were found increased by the effect of annealing at temperature of 200℃. Besides, on the wall of CNTS was observed fully covered with the RuO2 membrane by the method of cyclic voltammetry deposition, and the surface area can be great promoted at the electrochemical reactant. In the pulse electro-deposition, ruthenium oxide particle was found nucleated in uniform grain on the surface of CNTS.
The effect of nitrogen doping during CNTS growth followed by ruthenium oxide deposition was also discussed in this thesis. An amount of defects was generated by nitrogen atom occupied on the substitutional site of carbon, and porous CNTS were created. Ruthenium nano-particle can be trapped in the holes with suitable size. A nitrogen flow rate at 20 sccm was observed to achieve the best capacitive performance of 28mF/cm2, comparing to three other flow rates which have been chosen.
Finally, a simple package was made for the capacitor to test the device performance. It was found that the full electrode can keep almost the same value of capacitance during the 24 hours test time at scanning rate of 600-2000 mV/sec.
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