以電化學方式成長金奈米結構於碳電極並探討其對葡萄糖及過氧化氫的偵測應用

Abstract

本篇論文利用定電位還原法在碳電極上成長不同形貌的金奈米材料， 以不同濃度的 CTAC (cetyltrimethylammonium chloride) 及 NaNO3 配合不同的還原電壓 1.6 V 或1.8 V 控制金的形貌。，添加 20 mM NaNO3 及 9 mM CTAC 以 1.8 V 還原，產物為奈米級珊瑚狀的結構，改變電壓為 1.6 V 時，產物為扁平帶狀主軸側邊成長分枝，利用 Randles – Sevcik expression 測量金電極的電化學活性表面積，發現利用定電位還原法成長的金電極較平坦的金電極擁有更高的活性表面積及真實表面積，且以珊瑚狀的金電極最為顯著。我們利用循環伏安法和安培法探討不同形貌的金電極對葡萄糖及雙氧水的催化能力，由於珊瑚狀金電極具有高活性表面積及真實表面積，在中性 0.1 M PBS 緩衝液下，對葡萄糖及過氧化氫有最佳的催化能力，實驗結果得知，電極對雙氧水及葡萄糖偵測皆有高靈敏度和大線性範圍的特性，對於雙氧水和葡萄糖的生化感測具有應用性。

A straightforward electrochemical approach was developed for the fabrication of gold nanostructure on carbon electrode. Different morphologies of gold structures were synthesized by using HAuCl4, CTAC (cetyltrimethylammonium chloride ) and NaNO3 under direct voltage. Owing to the enhancement of electrode roughness by deposition, our electrodes show higher surface area than flat gold electrodes. Randles – Sevcik expression was used to calculate active surface areas ( ASA ) and cyclic voltammetry was used to estimate real surface areas ( RSA ) of various electrodes. The nanocoral electrode shows the highest RSA and adsorbs the largest amount of hydroxyl to form AuOH*, which is an active specie for glucose oxidation. We discuss the different catalysis toward glucose and hydrogen peroxide between various electrodes. Under cyclic voltammetry studies, flat gold electrodes show high overpotential for glucose and hydrogen peroxide oxidation that can be attenuated by using our deposited electrodes. Under amperometry study, our electrodes show better sensitivity than flat gold electrodes. The highest sensing ability of nanocoral provides a sensitivity of 22.56 □A mM－1cm－2 over a wide linear range from 0.05 mM to about 30 mM for glucose and 154.26 □A mM－1cm－2 over a relative narrow linear range from 0.05 mM to about 4.35 mM for hydrogen peroxide. The nanocoral electrode displays excellent electrochemical response to the glucose and hydrogen peroxide and it is a promise material for biosensor.