抗坏血酸在多壁碳纳米管修饰玻碳电极上的催化氧化  

Electrocatalytic Oxidation of Ascorbic Acid at Multi-walled Carbon Nanotube-modified Glassy Carbon Electrode

作　　者：张旭志[1] 焦奎[1] 赵常志[1] 孙伟[1] 杨涛[1] 

机构地区：[1]青岛科技大学化学与分子工程学院,青岛266042

出　　处：《应用化学》2007年第8期899-904,共6页Chinese Journal of Applied Chemistry

基　　金：国家自然科学基金(20375020;20405008;20635020);青岛市自然科学基金(04-2-JZP-8)资助项目

摘　　要：多壁碳纳米管(MWNTs)在质量分数为36%的HCl中超声纯化后于2.2mol/L的HNO3中超声氧化处理。处理好的MWNTs分散于N,N-二甲基甲酰胺(DMF)后滴加在玻碳电极表面制得MWNTs修饰电极(MWNTs/GCE),此电极对抗坏血酸(AA)有显著电催化氧化作用。在pH=4.0的B-R缓冲溶液中首次得到AA有2个分离良好的氧化峰,其电位分别在0.187和0.452V(vs.SCE)。根据AA分子与表面羧基化的MWNTs相结合后的电子传递性质对AA的2个氧化峰进行了初步解释。AA在MWNTs/GCE上的氧化为吸附控制的不可逆过程,其在电极表面的吸附量为1.02×10-9mol/cm2,2个氧化峰的电极反应标准速率常数分别为1.03×10-2和3.94×10-3s-1。应用MWNTs/GCE对AA的电催化氧化性质以微分脉冲伏安法对AA进行测定,在最佳实验条件下其线性范围为5.0×10-7～5.0×10-2mol/L,检测限为5.0×10-8mol/L(S/N=3)。Multi-walled carbon nanotubes （MWNTs） were pretreated ultrasonically in 36% HCl and then functionalized in 2.2 mol/L HNO3, and then dispersed in N, N-dimethylformamide （DMF）. The MWNTs modified glassy carbon electrode （MWNTs/GCE） was prepared by dropping 2 μL of MWNTs （0. 1 g/L） in DMF on the surface of a glassy carbon electrode. The MWNTs/GCE can catalyze the electro-oxidation of ascorbic acid （AA）. On the cyclic voltammogram, AA has two well-separated oxiditive peaks in pH = 4. 0 B-R buffer solution at 0. 187 V and 0. 452 V（vs. SCE）, respectively, the mechanism of which can be illustrated according to the molecular structure of AA and the electrocatalytic properties of the carboxylic acid group- functionalized MWNTs. The electro-oxidation of AA at MWNTs/GCE is an adsorption-controlled irreversible electrode process. The surface concentration of AA on the electrode was calculated to be 1.02 ×10^-9 mol/cm^2 and the standard rate constants of the electrode reactions of the two oxidative peaks of AA were calculated to be 1.03 ×10^-2 s^-1 and 3.94 ×10^-3 s^-1, respectively. AA was satisfactorily detected by using differential pulse voltammetry with a linear range from 5.0 ×10^-7 mol/L to 5.0 ×10^-2 mol/L and a detection limit of 5.0 ×10^-8 mol/L（ S/N = 3 ）.

关 键 词：多壁碳纳米管 抗坏血酸 修饰电极 电催化 伏安法 

分 类 号：O657.1[理学—分析化学]