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  • 學位論文

二氧化錳-奈米碳管複合電極應用於超級電容器之研究

The Study of MnO2-MWNTs Composite Electrodes for Supercapacitor Applications

指導教授 : 黃金花
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摘要


本研究在一般與柵欄式之奈米碳管陣列上,沉積二氧化錳製成複合電極,觀察並比較兩者複合電極結構、形貌與電化學特性之差異。由於在密集的奈米碳管陣列中不容易沉積均勻的二氧化錳,藉由柵欄式的方法可以促使電鍍液擴散至密集的奈米碳管陣列中進行沉積。首先以微波電漿輔助化學沉積法,在鈦金屬板上生長垂直的奈米碳管,再經過硝酸處理使奈米碳管具有親水性。接著將電極置入過錳酸鉀水溶液中,利用循環伏安法將二氧化錳沉積在奈米碳管上,電位範圍在-1~1 V間,並分別改變不同沉積掃描速率以及過錳酸鉀水溶液濃度,用以得到最佳的比電容值。 本研究使用拉曼光譜、掃描式電子顯微鏡以及高解析電子能譜分析複合電極中的形貌與結構。利用循環伏安法量測電化學特性,使用的電解液為0.5 M的硫酸鈉水溶液,電位範圍與掃描速率範圍分別為0~0.9 V與10~1000 mV/s,進行比電容值、長時間穩定性與交流阻抗頻譜的分析。一般與柵欄式之複合電極的最佳沉積參數之電化學量測結果,在10 mV/s的掃描速率下,比電容值分別為150.6 F/g與175.7 F/g。而在1000 mV/s高掃描速率下,比電容值分別為90.1 F/g與89.2 F/g。在掃描速率為50 mV/s下進行1000次長時間循環掃描,其維持率分別達到94 %與99 %,發現柵欄式之複合電極效能較佳,顯示柵欄式之二氧化錳/奈米碳管複合電極是具有發展潛力的超級電容器電極材料。

並列摘要


In this research, it is to illustrate MnO2 electrodeposit onto arrayed carbon nanotubes (CNTs) with fence type and normal type nanocomposite electrodes, then observing and comparing the differences of the composition structure, morphology and electrochemical properties. Since the surface of arrayed CNTs is high density, and not easy to uniformly deposit MnO2, so using the method of fence type can promote the proliferation of electroplating solution to diffuse into the dense arrayed CNTs during electrodepositing process. First, the arrayed CNTs are grown on Ti metal plate by microwave plasma-enhanced chemical vapor deposition(MPECVD), follow by a hydrophilic treatment in HNO3 solution. The electrode is then placed in KMnO4 solution to deposit MnO2 on CNTs by cyclic voltammetry; the potential range is applied between -1~1 V, and using different concentration in KMnO4 solution to achieve the optimum of the specific capacitance. The composition structure and morphology of nanocomposite electrodes are characterized by using Raman spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical performance is analyzed for the specific capacitance, long time stability and electrochemical impedance spectroscopy, using cyclic voltammetry in the electrolyte of 0.5 M Na2SO4 and potential range and scan rate between 0~0.9 V and 10~1000 mV/s, respectively. The electrochemical measures the optimum deposit conditions of both the normal and fence type nanocomposite electrodes. At 10 mV/s, the specific capacitance value is 150.6 F/g versus 175.7 F/g, and 90.1 F/g versus 89.2 F/g at 1000 mV/s, respectively. Besides, after 1000 cycles at 50 mV/s the capacitance retention can achieve 94 % versus 99 %. Thus, this experiment reveals that the fence type of MnO2/CNT nanocomposite electrodes had better performance, which can be deemed a potential method for the development of electrode materials for supercapacitors.

並列關鍵字

Supercapacitors MnO2

參考文獻


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