金电极羧基化表面的构建及电化学表征

Construction and electrochemical characterization of the functional carboxyl surface of a gold electrode

在金电极表面制备了对羧基苯硫酚(4-MBA)自组装单分子膜,构建了1种羧基功能化表面,利用循环伏安法和交流阻抗法对4-MBA自组装单分子膜电极(4-MBA/Au)进行了电化学表征,采用Randles等效电路对阻抗复平面图进行模拟,确定该电极体系的等效电路以及电化学参数,通过电荷传递电阻Rct求出电极的表面覆盖度为97.5%.结果表明,pH对4-MBA/Au的电化学特性有较大影响,随着pH的增大,循环伏安图中的阳极峰电流、阴极峰电流逐渐减小,电阻逐渐增大;交流阻抗法表征也得到了同样的结论,阻抗复平面图上半圆的直径随pH的增大而增大,即电荷传递电阻Rct逐渐增大.因此,通过改变pH,可控制表面羧基基团的结构状态.

functional carboxyl surface was constructed by fabricating 4-mercapto benzoic acid （4-MBA） self-assembled monolayer on the gold electrode（4-MBA/Au）. Cyclic voltammery（CV） and electrochemical impedance spectroscopy（EIS） have been used to study the electrochemical properties of 4-MBA/Au. The electrochemical behaviors of the 4-MBA/Au at different pH of[Fe（CN）6]^（3-/4-） were investigated. The Nyquist plot was simulated by using the traditional Randles equivalent circuit. The equivalent circuit of the electrode system and electrochemical parameters were determined. The surface coverage obtained on the electrode is 97.5 % through the mass transfer resistance Rct.