物理化学学报 >> 2013, Vol. 29 >> Issue (12): 2599-2607.doi: 10.3866/PKU.WHXB201310231

催化和表面科学 上一篇    下一篇

基于活性金电极上硫代水杨酸自组装单分子层的电化学表面增强拉曼光谱

刘文涵, 袁荣辉, 滕渊洁, 马淳安   

  1. 浙江工业大学化学工程与材料学院, 绿色化学合成技术国家重点实验室培育基地, 杭州 310032
  • 收稿日期:2013-07-29 修回日期:2013-10-21 发布日期:2013-11-28
  • 通讯作者: 刘文涵 E-mail:liuwh@zjut.edu.cn
  • 基金资助:

    国家自然科学基金(10804099), 浙江省科技厅公益项目(2012C37014)和浙江省重点科技创新团队(2011R09002-12)资助

Electrochemical SERS of Self-Assembled Monolayer of Thiosalicylic Acid Adsorbed on Activated Gold Electrodes

LIU Wen-Han, YUAN Rong-Hui, TENG Yuan-Jie, MA Chun-An   

  1. State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering and Materials, Zhejiang University of Technology, Hangzhou 310032, P. R. China
  • Received:2013-07-29 Revised:2013-10-21 Published:2013-11-28
  • Contact: LIU Wen-Han E-mail:liuwh@zjut.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (10804099), Commonweal Project of Science and Technology Department of Zhejiang Province, China (2012C37014), and Key Innovation Teams Project of Zhejiang Province, China (2011R09002-12).

摘要:

采用原位电化学表面增强拉曼光谱(EC-SERS)研究了硫代水杨酸(TSA)吸附在活性Au电极表面的自组装单分子层(SAMs). TSA在活性Au表面的化学吸附及不同酸碱度下的TSA浸饰单层膜的SERS光谱, 表明随pH值的增加, 峰强呈现2 个不同的下降阶段. 通过EC-SERS考察不同电富集时间和电位的影响, 显示在酸性介质和0.7 V及70 s 富集时间下, 可以获得最大EC-SERS信号, 并随着电位负移, 信号逐渐减弱, 直至基本消失, 表明TSA分子在Au表面排布状态会随外加条件的改变而发生变化. 通过计算TSA在不同pH值下的分布分数以及探针分子在不同电位下的增强因子(EF), 结合SERS和EC-SERS的变化走势对比, 得出TSA在活性Au表面自组装形成单分子层/膜的机理, 指出由于TSA不同的电化学吸附取向, 以及高负电位下的还原/脱附作用, 使得Au表面拉曼活性降低, 造成EF显著减小, 不可逆地失去了SERS的活性.

关键词: 电化学表面增强拉曼光谱, 硫代水杨酸, 自组装单分子层, 金电极, 增强因子

Abstract:

Amonolayer film of thiosalicylic acid (TSA) adsorbed on activated gold electrodes was investigated by using in situ electrochemical surface-enhanced Raman scattering (EC-SERS). In the SERS spectra of selfassembled monolayers in solutions with different pH values, two peaks with Raman intensities that decreased with increasing pH were observed. The optimum EC-SERS signals were obtained at 0.7 V and 70 s, and it was found that the intensities became weaker, and the peaks eventually disappeared, when the potential was negatively shifted. This showed that the alignments of TSA assembled on the gold surface changed in response to changes in the external conditions. The absorption mechanism of the TSA monolayer was investigated by calculating the distribution fraction of TSA at different pH values and the enhancement factor (EF) at different potentials, using a combination of SERS and EC-SERS. As a result of different electrochemical absorption orientations of TSA and its reduction/desorption behavior at high negative potentials, the Raman enhanced effect of TSA on gold was significantly reduced and the SERS activity was irreversibly lost.

Key words: Electrochemical surface-enhanced Raman scattering, Thiosalicylic acid, Self-assembled monolayer, Gold electrode, Enhancement factor

MSC2000: 

  • O647