Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States.
Anal Chem. 2012 Oct 16;84(20):8797-804. doi: 10.1021/ac302219p. Epub 2012 Oct 3.
Here we report the theory and experimental study of the steady-state voltammetric behavior of a microelectrode used as a limiting pole in a closed bipolar electrochemical cell. We show that the steady-state voltammetric response of a microelectrode used in a closed bipolar cell can be quantitatively understood by considering the responses of both poles in their respective conventional two-electrode setups. In comparison to a conventional electrochemical cell, the voltammetric response of the bipolar cell has a similar sigmoidal shape and limiting current; however, the response is often slower than that of the typical two-electrode setup. This leads to a broader voltammogram and a decreased wave slope, which can be somewhat misleading, causing the appearance that the process being studied is irreversible when it instead can be a result of the coupling of two reversible processes. We show that a large limiting current on the excess pole would facilitate the observation of a faster voltammetric response and that both redox concentration and electrode area of the excess pole affect the wave shape. Both factors should be maximized in electroanalytical experiments in order to obtain fast voltammetric responses on the main electrode of interest and to detect quick changes in analyte concentrations.
本文报告了作为闭双极电化学池限流器使用的微电极的稳态伏安行为的理论和实验研究。结果表明，通过考虑两个电极各自在传统的两电极设置中的响应，可以定量理解闭双极池中使用的微电极的稳态伏安响应。与传统的电化学池相比，双极池的伏安响应具有相似的“S”形形状和极限电流，但响应通常比典型的两电极设置慢。这导致了更宽的伏安图和降低的波斜率，这可能会有些误导，导致所研究的过程看起来是不可逆的，而实际上可能是两个可逆过程的耦合结果。我们表明，过量电极上的大极限电流将有助于观察更快的伏安响应，并且过量电极的氧化还原浓度和电极面积都影响波的形状。在电分析实验中，应该最大化这两个因素，以在感兴趣的主电极上获得快速的伏安响应，并检测分析物浓度的快速变化。
