Enhanced electroanalysis in lithium potassium eutectic (LKE) using microfabricated square microelectrodes.
Enhanced electroanalysis in lithium potassium eutectic (LKE) using microfabricated square microelectrodes.
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DOI：
10.1021/ac5030842
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发表时间：
2014-11
影响因子：
7.4
通讯作者：
D. Corrigan;E. Blair;J. Terry;A. Walton;A. Mount
中科院分区：
文献类型：
--
作者：
D. Corrigan;E. Blair;J. Terry;A. Walton;A. Mount
熔盐（MS）是化学和电化学加工的一种有吸引力的介质，因此对MS兼容的分析技术存在需求。然而，含有氧化还原物质的MS由于其腐蚀性、显著的热对流和所涉及的高温而呈现出进行分析测量的具有挑战性的环境。本文概述了微加工方形微电极（MSM）的制造和表征设计用于电化学分析的MS系统。它们的设计能够精确控制电极尺寸，通过高温操作设计使不同热膨胀引起的应力最小化，并通过有效绝缘使腐蚀性侵蚀最小化。用于表征的示例性MS系统是氯化锂/氯化钾共晶（LKE），其在高温化学核燃料后处理、金属精炼、熔盐电池和电力电池中具有潜在的应用。在400和500 °C（673和773 K）之间的氧化还原离子范围内观察到的响应是定量的，并且是微电极的典型响应。MSM还表现出降低的iR下降、稳态扩散限制响应以及在环境条件下观察到的微电极对对流的敏感性降低，以及与宏电极相比这些电极的预期。扩散系数得到与文献值密切一致，更容易和更高的精度和准确度比宏电极和以前的微电极测量。还证明了从氧化还原物质混合物中提取单个物理参数（如后处理所需）和在线监测所需的长时间测量的可行性。总之，这表明MSM提供了广泛适用于在一系列MS系统中表征氧化还原物质的增强的电极装置。
Molten salts (MSs) are an attractive medium for chemical and electrochemical processing and as a result there is demand for MS-compatible analysis technologies. However, MSs containing redox species present a challenging environment in which to perform analytical measurements because of their corrosive nature, significant thermal convection and the high temperatures involved. This paper outlines the fabrication and characterization of microfabricated square microelectrodes (MSMs) designed for electrochemical analysis in MS systems. Their design enables precise control over electrode dimension, the minimization of stress because of differential thermal expansion through design for high temperature operation, and the minimization of corrosive attack through effective insulation. The exemplar MS system used for characterization was lithium chloride/potassium chloride eutectic (LKE), which has potential applications in pyrochemical nuclear fuel reprocessing, metal refining, molten salt batteries and electric power cells. The observed responses for a range of redox ions between 400 and 500 °C (673 and 773 K) were quantitative and typical of microelectrodes. MSMs also showed the reduced iR drop, steady-state diffusion-limited response, and reduced sensitivity to convection seen for microelectrodes under ambient conditions and expected for these electrodes in comparison to macroelectrodes. Diffusion coefficients were obtained in close agreement with literature values, more readily and at greater precision and accuracy than both macroelectrode and previous microelectrode measurements. The feasibility of extracting individual physical parameters from mixtures of redox species (as required in reprocessing) and of the prolonged measurement required for online monitoring was also demonstrated. Together, this demonstrates that MSMs provide enhanced electrode devices widely applicable to the characterization of redox species in a range of MS systems.