硫堇衍生化自组装膜修饰金电极的电化学性质及其对抗坏血酸的电催化氧化

将硫堇共价键合到自组装在金电极表面的半胱胺单分子层上,制成了衍生化自组装单分子膜修饰电极,并用电化学方法研究了它的电化学性质.循环伏安图显示其在pH＝7.7的磷酸盐缓冲液中,于－0.45～＋0.50V(vs.SCE)范围内有2对氧化还原峰.峰电位分别为E_pa¹＝214mV。E_pc¹＝82mV,E_pa2＝－75mV,E_pc2＝－160mV(vs.SCE).pH在5.0～9.0范围内,峰1有2个质子参与反应,峰2有1个质子参与反应.它的表面电子转移速率常数k_s＝0.02S^－1.此膜对抗坏血酸的氧化有催化作用,其氧化过电位较在裸金电极上降低了约250mV.催化电流与抗坏血酸的浓度在1.0×10^-6～4.0×10^-3mol/L范围内呈良好的线性关系.抗坏血酸催化氧化的异相速率常数为2.68×10^-3cm/s.

The Electrochemical Characteristics of Gold Electrode Modified by Thionine Covalently Bound to Self-assembled Cysteamine Monolayer and Its Electrocatalytic Oxidation for Ascorbic Acid

Agold electrode modified by thionine covalently bound to self-assembled cysteamine monolayer (Th-SAM) has been prepared.The electrochemical properties of this ThSAMmodified electrode was investigated by electrochemical methods.There were two redox couples when it was swept in the range of -0.45-+0.50 V(vs.SCE) by cyclic voltammetry.As to pH7.7, the peak potentials were E_pa¹＝214mV。E_pc¹＝82mV,E_pa²＝－75mV,E_pc²＝－160mV, respectively.The participating number of proton was 2 for peak 1 and 1 for peak 2 in the pHrange between 5.0 and 9.0.The surface electron transfer rate constant(k_s)of peak 2 was 0.02 s^-1.The Th-SAMmodified electrode could be successfully used for the electrocatalytic oxidation of ascorbic acid and the catalytic currents increased linearly with the ascorbic acid concentration in the range of 1.0 ×10^-6-4.0×10^-3 mol/L-The heteroge neous electron transfer rate constant was about 2.68×10^-3 cm/s.