Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium
Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium
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DOI：
10.1002/elan.200503300
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发表时间：
2005-10
期刊：
影响因子：
3
通讯作者：
A. Walcarius;E. Sibottier
中科院分区：
文献类型：
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作者：
A. Walcarius;E. Sibottier
通过自组装技术、溶胶-凝胶法和电化学调节电极/溶液界面的pH，在金电极上沉积了附着良好的胺功能化多孔二氧化硅薄膜。首次在一次性金电极(Au-Cd电极)上形成了部分自组装的硫代丙基三甲氧基硅烷(MPTMS)单分子膜。将经SO处理的MPTMS-Au-Cd电极浸泡在含有(3-氨丙基)-三乙氧基硅烷(APTES)和正硅酸乙酯(TEOS)的稳定溶胶溶液中(pH为3)。APTES和TEOS前驱体的缩聚反应是通过在电极/溶液界面施加负电位，在电极/溶液界面产生局部pH升高并促进胺功能化二氧化硅薄膜的沉积来实现的，由于MPTMS单分子膜起到了“分子胶”的作用，使其很好地附着在电极表面。研究了影响电沉积过程的各种参数，并用循环伏安法表征了膜对溶液中氧化还原探针的渗透性。然后将胺功能化的二氧化硅薄膜电极用于铜(II)物种的预富集，然后用阳极溶出差示脉冲伏安法进行电化学检测。然而，要获得高灵敏度，需要应用电化学预活化步骤，因为大多数有机官能团是以氨基的形式存在的(因为薄膜是从酸性溶胶中制备的)。这是通过在电极表面施加足够负的电位来减少质子，从而增加膜内的胺/铵比，从而提高预浓缩过程的效率来实现的。优化后的装置用于水-乙醇介质中铜(II)的测定，在0.10-10μM浓度范围内具有良好的线性关系。
Well-adherent amine-functionalized porous silica films have been deposited on gold electrodes by combining the self-assembly technology, the sol–gel process, and the electrochemical modulation of pH at the electrode/solution interface. A partial self-assembled monolayer of mercaptopropyl-trimethoxysilane (MPTMS) was first formed on disposable gold electrodes from recordable CDs (Au-CDtrodes). The so pretreated MPTMS-Au-CDtrodes were immersed in a stable sol solution (pH 3) containing (3-aminopropyl)-triethoxysilane (APTES) and tetraethoxysilane (TEOS). Polycondensation of the APTES and TEOS precursors was then achieved by applying a negative potential for a given period of time to generate a local pH increase at the electrode/solution interface and promote the deposition of the amine functionalized silica film adhering well to the electrode surface owing to the MPTMS monolayer acting somewhat as a “molecular glue”. Various parameters affecting the electrodeposition process have been studied and the film permeability to redox probes in solution was characterized by cyclic voltammetry. The amine-functionalized silica film electrodes were then applied to the preconcentration of copper(II) species prior to their electrochemical detection by anodic stripping differential pulse voltammetry. Getting high sensitivity has however required the application of an electrochemical pre-activation step as the majority of the organo-functional groups were in the form of ammonium moieties (because the film was prepared from an acidic sol). This was achieved by applying a sufficiently negative potential to the electrode surface to reduce protons and increase consequently the amine-to-ammonium ratio within the film and, thus, the efficiency of the precocentration process. The resulting device was then optimized for copper(II) determination in hydroalcoholic medium, giving rise to a linear response in the 0.1–10 μM concentration range.