電化學法成長金屬奈米材料

Abstract

在本論文中，我們發展界面活性劑(烷基三甲基氯化銨)輔助電化學法，包含賈凡尼還原法與電化學沉積法，成功地成長銅與金一維奈米結構於電極上。 首先，我們利用氯化銅與金屬鋁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單晶銅奈米帶。奈米帶帶厚小於15 nm，帶寬範圍為30-150 nm，長度可達10 □m. 第二部份，我們利用電化學沉積法直接成長銅奈米帶於碳電極上。奈米帶平均帶寬為50 nm，帶厚約20 nm，長度可達數10 □m。改變反應物濃度與施加電位可調控奈米帶帶寬。循環伏安實驗展示銅奈米帶電極(電沉積量0.5 C，幾何面積0.018 cm2)具有增強電催化葡萄糖氧化的能力。在葡萄糖安培法感測中，此電極展現高靈敏度(79.8 □A/mM) 與低偵測極限(0.1 □M)。 第三部份為十二烷基三甲基氯化銨輔助賈凡尼還原法成長似寶塔蓋頂的四方形銅奈米柱陣列於金電極上。奈米柱四個長邊為{100}晶面構成，奈米柱長範圍為1-6 □m，寬為150 + 25 nm。場發射量測顯示銅奈米柱陣列在turn-on field 12.4 V □m−1有10 □A cm−2電流密度且增強因子□□為713. 最後部分，我們延伸界面活性劑輔助賈凡尼還原法直接成長金奈米錐與海膽結構於矽基材上。比較不同奈米結構對場發射性質的影響，實驗結果顯示奈米錐與奈米海膽都具有場發射性質，尤其反應十八小時的奈米海膽結構具高長寬比的奈米線(線徑50-100 nm, 線長1-3 □m, 長寬比20-30)，展現最佳的場發射效能(turn-on field 6.3 V□m-1, □□1150)。

In this thesis, we developed surfactant-assisted electrochemical methods, including galvanic reduction and electrochemical deposition, to grow one-dimensional (1D) Cu and Au nanostructures on solid electrodes. First, the single crystalline face-centered cubic phase (fcc) Cu nanobelts (NBs) were prepared by reacting CuCl2(aq) with Al(s) in an aqueous solution of CTAC (cetyltrimethylammonium chloride) and HNO3. The Cu NB exhibited a high-quality ribbon-like nanostructure with a thickness less than 15 nm, a width of 30-150 nm, and a length up to 10 □m. In the second section, Cu NBs with a small and uniform belt-width were grown directly on carbon electrodes by using electrochemical deposition. The average width, thickness and length of the NBs were about 50 nm, 20 nm and several tens of micrometers, respectively. The belt-width can be controlled by changing reactant concentration and electrical field applied. Cyclic voltammetric (CV) experiments showed that a Cu NB electrode grown by a reduction charge of 0.5 C on a substrate of 0.018 cm2 enhanced glucose oxidation ability. For glucose sensing, the electrode exhibited a high sensitivity of 79.8 □A/mM and a low detection limit of 0.1 □M in amperometric detection. In the third section, growth of arrays of pagoda-topped tetragonal Cu nanopillar (length: 1-6 □m, width: 150 ± 25 nm) with {100}-side faces on Au/glass is achieved by a simple galvanic reduction of CuCl2(aq) by Al(s) in DTAC(aq). Field emission (FE) measurement shows that the Cu nanopillars can emit electrons (10 □Acm-2) at a turn-on field of 12.4 V□m-1 with a calculated field enhancement factor □□of 713. Finally, this surfactant-assisted galvanic reduction was extended to grow directly Au nanothorns and nanourchins on Si. Nanothorns and nanourchins were prepared by reacting HAuCl4(aq) with Sn(s) in the presence of only NaNO3(aq) and both CTAC(aq) and NaNO3(aq), respectively, which were important to the product morphology development. FE measurements reveal that they have different FE performances based on their morphologies. Among them, Au nanourchins grown at 18 h exhibited the best FE efficiency (turn-on-field 6.3 V□m-1, □ 1150) because they protrude radially high aspect ratio (20-30) nanowires.