Visualizing the Zero-Potential Line of Bipolar Electrodes with Arbitrary Geometry
Visualizing the Zero-Potential Line of Bipolar Electrodes with Arbitrary Geometry
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DOI：
10.1021/acs.analchem.7b04881
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发表时间：
2018-06-05
影响因子：
7.4
通讯作者：
Wang, Wei
中科院分区：
文献类型：
--
作者：
Li, Meng;Liu, Shasha;Wang, Wei
在典型的双极电化学（BPE）配置中，施加在两个驱动电极之间的电压通过填充在微通道中的溶液诱导电位降，导致溶液与BPE之间的界面电位差沿BPE沿着变化。在目前的工作中，我们采用了最近开发的等离子体成像技术映射的非法拉第充电过程下的各种几何形状，包括圆形，三角形，六边形，星星，菱形形状的双极电极的表面电位的分布，从零电位线（LZP）的可视化和确定。我们进一步研究了LZP对电极几何形状和外电场分布的依赖性，并用电荷平衡机制解释了实验结果。三角形和星形的BPE显示出与其他对称几何形状的BPE完全不同的LZP特征。这些实验获得的电位分布都与电磁模拟结果吻合良好。最后，研究了三角形BPE在法拉第反应下的零超电势线。实验结果证实了在BPE的相应末端发生法拉第反应时，LZO发生了位移。目前的工作表明，第一个实验能力，以映射任意几何形状下的任意驱动场的BPE的潜在分布。这将有助于电极和微通道的几何形状的设计和优化，从而促进其在化学传感和材料合成中的应用。
In a typical bipolar electrochemistry (BPE) configuration, voltage applied between the two driving electrodes induced a potential drop through solution filled in the microchannel, resulting in an interfacial potential difference between solution and BPE varied along the BPE. In the present work, we employed a recently developed plasmonic imaging technique to map the distribution of surface potential of bipolar electrodes with various geometries including round, triangle, hexagon, star, and rhombus shapes under the nonfaradaic charging process, from which the line of zero potential (LZP) was visualized and determined. We further investigated the dependence of LZP on electrode geometry and the distribution of external electric field and explained the experimental results with a charge balance mechanism. The triangular and star-shaped BPEs show quite different LZP features from the other ones with symmetrical geometry. These experimentally obtained potential distributions are all in good agreement with electromagnetic simulations. Finally, the line of zero overpotential (LZO) of the triangular-shaped BPE under faradaic reactions were investigated. The results confirm the shift of LZO when faradaic reactions occurred at the corresponding ends of BPE. The present work demonstrates the first experimental capability to map the potential distribution of BPE with arbitrary geometry under an arbitrary driving field. It is anticipated to help the design and optimization on the geometry of electrodes and microchannels with implications for boosting their applications in chemical sensing and materials synthesis.