奈米銀線之製備、性質與感測應用

Abstract

在本論文中，我們以賈凡尼還原法配合界面活性劑(烷基三甲基氯化銨)輔助成長法，成功地將海膽狀奈米銀線成長於電極上。 首先，我們利用銅與硝酸銀的賈凡尼自發性氧化還原反應，在含有十六烷基三甲基氯化銨與硝酸的水溶液中成長海膽狀奈米銀線於市售網版印刷碳電極上，其直徑約為80-120 nm，藉由不同的反應時間，長度可達10 □m左右。經由結構分析顯示奈米銀線為單晶且成長方向為[110]。除此之外，我們也利用類似的反應溶液，在鍍有金或鉑的氧化銦錫(ITO)導電玻璃上，以電化學沉積法也能得到奈米銀線。 第二部分我們利用海膽狀奈米銀線，觀察其表面電漿共振特性。研究發現，奈米銀線在紫外光區有表面電漿共振吸收特性，其主要吸收位置在380 nm與500 nm附近。我們更進一步的深入討論其在表面增強拉曼散射之應用，結果顯示當我們以532 nm的雷射光作為激發光源，並以染料分子( Rhodamine 6G)作為偵測分子，可以得到最佳的偵測極限為10-16 M，其分析增強因子(Analytical Enhancement Factor)為1013。利用表面增強拉曼光譜影像分析(SERS mapping images)，證明其有單分子偵測(single molecule detection)能力。 最後我們利用海膽狀奈米銀線作為電極，進行過氧化氫電化學感測實驗。循環伏安法實驗展示海膽狀奈米銀線具有增強電催化過氧化氫還原的能力，在過氧化氫安培法感測中，此電極展現高靈敏度(4705 □A mM-1 mg-1 cm-2)，其偵測範圍為0.05 mM-10.35 mM，偵測極限可達10 □M。這也是第一個利用奈米銀線作為非酵素型過氧化氫感測應用(non-enzymatic H2O2 sensing application)。

In this thesis, we demonstrate a simple low-cost galvanic reduction with surfactant-assisted method to grow urchin-like Ag nanowires (NWs) on electrodes. First, urchin-like Ag NWs on screen-printed carbon (SPC) electrodes were prepared via glavanic reductions of AgNO3(aq) solutions in the presence of cetyltrimethylammonium chloride (CTAC) by Cu foil. The diameters of the nanowires are about 80-120 nm, and their lengths are up to 10 □m. The Ag NW is single crystalline and tends to grow along the [110] direction. Moreover, we can use electrochemical deposition to synthesize Ag NW on Au or Pt seeding layers on Indium Tin Oxide (ITO) substrates with similar reaction condition. The second subject is surface plamon resonance (SPR) property of urchin-like Ag NWs. The absorption peak at ca. 380 nm was attributed to the plasmon response from the transverse mode of the NWs while the broad band extended from 500 nm was assigned to the longitudinal modes of the NWs with different aspect ratios. Furthermore, we used Rhodamine 6G as the probe molecule, and the the excitation wavelength of 532 nm was applied for the surface enhanced Raman scattering (SERS) experiments. The detection limit of Rhodamine 6G on the urchin-like Ag NWs can be as low as 10-16 M while the analytical enhancement factor is about 1013. Raman mapping images confirm that a single R6G molecule on the substrate can be detected. The final subject is hydrogen peroxide sensing application. Cyclic voltammetric experiments using the Ag NWs as the working electrode showed electrocatalytic H2O2 reduction. For H2O2 sensing, the electrode exhibited a high sensitivity of 4705 □A mM-1 mg-1 cm-2 from 50 □M to 10.35 mM and a measurable detection limit of 10 μM in amperometric detection. This is the first report on Ag NWs for non-enzymatic H2O2 sensing.