- 學位論文
製備以碲為基礎之奈米材料與其電化學應用
Preparation and electrochemical applications of tellurium-based nanomaterials
摘要
本論文主要分為兩部分：第一部分使用修飾碲奈米線之玻璃碳電極用於電化學偵測多巴胺；第二部分成長碲–鉑奈米網於碳纖維微電極上，用於微小化之直接甲醇燃料電池中電催化甲醇氧化。在電化學偵測多巴胺方面，以聯胺將二氧化碲粉末還原並成長成平均長600奈米、寬16奈米之碲奈米線後，將其溶液以直接滴加方式修飾於玻璃碳電極表面，乾燥後再滴上具電荷選擇性之聚合物Nafion以提高對多巴胺之選擇性。相較於未修飾之玻璃碳電極，使用以碲奈米線及Nafion修飾之電極進行電化學偵測時，不僅多巴胺的氧化訊號增為約兩倍，更可提升其對多巴胺之選擇性，在高濃度之生物體內常見干擾物如抗壞血酸及尿酸的存在下，亦可達到良好的偵測極限（1.0 nM）及線性範圍（5.0 nM- 1.0 uM）。本研究進一步利用會受高鉀離子濃度刺激進而胞吐多巴胺的PC12類神經細胞驗證此電極之準確性，在每毫升含5×105個細胞時可得到多巴胺的胞外濃度為0.59 ± 0.07 uM，與文獻相符。微小化直接甲醇燃料電池方面，則利用硼氫化鈉還原鹼性環境下之三氧化碲離子，在直徑30微米、長度5公分，裝載於玻璃毛細管中之碳纖維上形成由碲奈米線組成之三維碲奈米網結構。一方面以其網狀結構作為模板，另一方面利用其易被氧化的性質作為還原劑，將六氯鉑酸根離子利用離子置換反應還原於碲奈米網上，形成碲–鉑奈米網狀結構，用於直接甲醇燃料電池的陽極進行甲醇氧化反應之催化。因為此電極具有小體積及高表面積的特性，可以達到節省貴金屬使用量、提升單位面積催化電流的效果，經修飾網狀碲–鉑奈米網後，在含1.0 M甲醇的0.5 M硫酸中，電化學活性表面積可達129.2 cm2 g-1，電流密度及質量活性分別可達20.0 mA cm-2及1.2 A mg-1，其電流穩定度及耐一氧化碳毒化程度亦較商用鉑粉高。此外，在一毛細管內安裝多支碳纖維，其催化電流亦可達到等比例的增加。
並列摘要
The thesis consisted two parts: the first part focused on the electrochemical detection of dopamine using tellurium-nanowire-coated glassy carbon electrode; the second part is about the growth of 3D, Te/Pt nanonetworks on carbon fiber microelectrode as the catalyst on miniaturized direct methanol fuel cells (DMFCs). For the dopamine detection part, tellurium-nanowire-coated glassy carbon electrodes (TNGCEs) were prepared by direct deposition of tellurium nanowires, 600 ± 150 nm in length and 16 ± 3 nm in diameter, onto glassy carbon electrodes, which were further coated with Nafion to improve their selectivity and stability. Compared to the GCE, the TNGCE is more electroactive for DA, and its selectivity toward DA over ascorbic acid (AA) and uric acid (UA) is also greater. By applying differential pulse voltammetry, the TNGCE provides a limit of detection of 1.0 nM for DA in the presence of 0.5 mM AA and UA and gives good linearity of the oxidation current against the concentration of DA (5.0 nM to 1.0 uM). TNGCEs have been applied to determine the concentration of dopamine to be 0.59 ± 0.07 uM in PC12 cells. For the miniaturized DMFC part, Te/Pt nanonetworks decorated carbon fiber microelectrodes (Te/PtCFMEs) have been fabricated by galvanic replacement reaction between Te nanonetworks and PtCl62- ion and employed for catalysis of methanol oxidation in direct methanol fuel cells (DMFCs). As anodic catalyst in DMFC, Te/PtCFMEs provide high electrochemical active surface area (129.2 cm2 g-1), good catalytic activity (1.2 A mg-1), great current density (20.0 mA cm-2), long durability and acceptable tolerance toward the poisoning species (If/Ib > 1.3) for methanol oxidation in 0.5 M sulfuric acid containing 1 M methanol. By applying multiple carbon fibers, the CFME can generate even higher electrooxidative current.
參考文獻
延伸閱讀
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