Suppression of Resistive Coupling in Nanogap Electrochemical Cell: Resolution of Dual Pathways for Dopamine Oxidation.
Suppression of Resistive Coupling in Nanogap Electrochemical Cell: Resolution of Dual Pathways for Dopamine Oxidation.
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纳米间隙电化学电池中电阻耦合的抑制：多巴胺氧化双途径的解决。
DOI：
10.1016/j.snb.2024.135440
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发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Amemiya,Shigeru
中科院分区：
文献类型：
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作者：
Amiri,Amir;Ravi,ManuJyothi;Huang,Siao-Han;Janda,DonaldC;Amemiya,Shigeru
纳米间隙电池包括两个工作电极，它们被纳米宽的溶液隔开，以实现前所未有的电化学测量。然而，强大的纳米间隙测量可能会受到两个电极之间的电阻耦合的严重干扰，从而产生错误的电流响应。在此，我们采用基于双碳纤维微电极的纳米间隙电池来抑制电阻耦合，以评估固有电流响应。具体而言，我们修改了一个商业bipotentiostat，以补偿欧姆电位下降共享的两个电极通过共同的电流通路与溶液中的固定电阻。通过非法拉第过程和法拉第过程的电阻耦合被抑制以消除错误的电流响应。我们的方法被应用于研究多巴胺在碳纤维微电极上氧化的机制，作为重要的神经递质的电化学传感器。电阻耦合被抑制，以显示基于吸附和非吸附形式的多巴胺氧化成相应形式的多巴胺-邻醌的固有电流响应。同时双氧化途径的第一次观察到，可以通过非协调一致或协调一致的吸附耦合电子转移机制介导。对于多巴胺的双电子氧化，这两种机理不能区分，因为它不能确定中间体多巴胺半醌是否吸附在电极表面上。值得注意的是，我们的方法将是有用的，以体现内在的电流响应，而没有电阻耦合的纳米间隙和微间隙，这是太窄，以消除共同的解决方案电阻，通过优化参考电极的位置。
A nanogap cell involves two working electrodes separated by a nanometer-wide solution to enable unprecedented electrochemical measurements. The powerful nanogap measurements, however, can be seriously interfered with by resistive coupling between the two electrodes to yield erroneous current responses. Herein, we employ the nanogap cell based on double carbon-fiber microelectrodes to suppress resistive coupling for the assessment of intrinsic current responses. Specifically, we modify a commercial bipotentiostat to compensate the Ohmic potential drop shared by the two electrodes through the common current pathway with a fixed resistance in the solution. Resistive coupling through both non-Faradaic and Faradaic processes is suppressed to eliminate erroneous current responses. Our approach is applied to investigate the mechanism of dopamine oxidation at carbon-fiber microelectrodes as important electrochemical sensors for the crucial neurotransmitter. Resistive coupling is suppressed to manifest the intrinsic current responses based on the oxidation of both adsorbed and non-adsorbed forms of dopamine to the respective forms of dopamine-o-quinone. The simultaneous dual oxidation pathways are observed for the first time and can be mediated through either non-concerted or concerted mechanisms of adsorption-coupled electron transfer. The two mechanisms are not discriminated for the two-electron oxidation of dopamine because it can not be determined whether the intermediate, dopamine semi-quinone, is adsorbed on the electrode surface. Significantly, our approach will be useful to manifest intrinsic current responses without resistive coupling for nanogaps and microgaps, which are too narrow to eliminate the common solution resistance by optimizing the position of a reference electrode.