Characterization of alkanethiol-self-assembled monolayers-modified gold electrodes by electrochemical impedance spectroscopy
Characterization of alkanethiol-self-assembled monolayers-modified gold electrodes by electrochemical impedance spectroscopy
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DOI：
10.1016/j.jelechem.2005.09.007
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发表时间：
2006-01-01
影响因子：
4.5
通讯作者：
Pingarrón, JM
中科院分区：
文献类型：
--
作者：
Campuzano, S;Pedrero, M;Pingarrón, JM
采用电化学阻抗谱（EIS）研究了3-巯基丙酸（MPA）和11-巯基十一烷酸（MUA）在金电极（AuE）上自组装成的单分子膜及其混合膜的结构和电化学性质.这些结果进行了比较，通过循环伏安法（CV）。通过电荷转移电阻和孔径模型使用阻抗测量来确定单层表面覆盖度。循环伏安法考虑金氧化物的形成/去除，以及氧化还原探针的氧化/还原过程，也被用来计算表面覆盖率。考虑到在电化学实验过程中所研究的单分子膜的稳定性，在修饰和未修饰的电极处的电荷转移的势垒的比较导致用于估计由每个所考虑的单分子膜给出的表面覆盖百分比的适当方法。结果表明，MPA-单分子层涂层电极的行为类似于微电极阵列，与针孔作为微电极。针孔的平均尺寸和分离，由孔径模型估计，分别为1.9和21 μ m。然而，MUA形成紧密堆积的单层，其充当离子绝缘体并且几乎无缺陷。评价了MPA和MUA自组装膜在金电极（AuE）上的吸附动力学。正如预期的那样，MPA和MUA的混合单分子膜显示出长链和短链烷醇单分子膜的特性。(c)2005 Elsevier B. V.保留所有权利。
The structure and electrochemical properties of pure and mixed monolayers of 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) self-assembled on a gold disk electrode (AuE) have been investigated by electrochemical impedance spectroscopy (EIS) in electrolytes containing a one-electron redox couple. These results are compared with those obtained by cyclic voltammetry (CV). The monolayer surface coverage was determined using impedance measurements through the charge-transfer resistance, and by the pore size model. Cyclic voltammetry considering gold oxide formation/removal, as well as the oxidation/reduction process of a redox probe, was also employed to calculate the surface coverage. Taking into account the stability of the studied monolayers during the electrochemical experiment, the comparison of the barrier to charge transfer at both, the modified and the unmodified electrodes, resulted to be an appropriate method for estimating the surface coverage percentage given by each of the considered monolayers. The obtained results demonstrated that the MPA-monolayer-coated electrode behaves like a microelectrode array, with pinholes acting as the microelectrodes. The average size and the separation of the pinholes, estimated by the pore size model, are 1.9 and 21 mu m, respectively. However, MUA forms a closely packed monolayer that acts as an ionic insulator and is virtually defect-free. The adsorption kinetics of MPA and MUA SAMs on the gold electrode (AuE) was evaluated. As expected, mixed monolayers of MPA and MUA show characteristics of both, long and short-chain alkanethiol monolayers. (c) 2005 Elsevier B.V. All rights reserved.