Nanopipet Voltammetry of Common Ions across the Liquid-Liquid Interface. Theory and Limitations in Kinetic Analysis of Nanoelectrode Voltammograms
Nanopipet Voltammetry of Common Ions across the Liquid-Liquid Interface. Theory and Limitations in Kinetic Analysis of Nanoelectrode Voltammograms
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DOI：
10.1021/ac9022428
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发表时间：
2010-01-01
影响因子：
7.4
通讯作者：
Mirkin, Michael V.
中科院分区：
文献类型：
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作者：
Rodgers, Patrick J.;Amemiya, Shigeru;Mirkin, Michael V.
进行了两种不混溶的电解质溶液（ITIE）之间在纳米纤维支持的界面上的离子转移（IT）反应的有限元模拟，并以分析近似的形式推广了数值结果。开发的理论是对快速IT反应的稳态伏安图进行动力学分析的新方法的基础。与常规伏安协议不同，我们的方法要求将可转移的离子最初添加到两个液相中，即，在纳米胶体和外部溶液中的填充溶液中。所得的稳态IT伏安图包括两个波，对应于公共离子进入Die Pipet及其出口到外部溶液中。我们证明，对于快速IT反应的热力学和动力学参数的精确测定，入口和出口波是对移液几何形状表征的表征和精确测定所必需的。这样，可以消除动力学参数中的大型不确定性，这些参数是先前报道的方法，用于分析IT在移液器支持的ITIE或固体电极时的电子传递时的几乎可逆稳态伏安图。数值模拟还表明，纳米级ITIES边缘的较高电流密度增加了移动器的带电内表面对IT过程的静电效应的重要性。
Finite element simulations of ion transfer (IT) reactions at the nanopipet-supported interface between two immiscible electrolyte solutions (ITIES) were carried out, and the numerical results were generalized in the form of an analytical approximation. The developed theory is the basis of a new approach to kinetic analysis of steady-state voltammograms of rapid IT reactions. Unlike the conventional voltammetric protocol, our approach requires the initial addition of a transferable ion to both liquid phases, i.e., to the filling solution inside a nanopipet and the external solution. The resulting steady-state IT voltammogram comprises two waves corresponding to the ingress of the common ion into die pipet and its egress into the external solution. We demonstrate that both ingress and egress waves are required for characterization of pipet geometry and precise determination of thermodynamic and kinetic parameters for rapid IT reactions. In this way, one can eliminate large uncertainties in kinetic parameters, which are inherent in the previously reported approaches to analysis of nearly reversible steady-state voltammograms of either IT at pipet-supported ITIES or electron transfer at solid electrodes. Numerical simulations also suggest that higher current density at the edge of the nanoscale ITIES increases the significance of electrostatic effects exerted by the charged inner surface of a pipet on IT processes.