Direct Evaluation of the Electrokinetic Properties of Electrolytes in a Nanochannel using Electrical Impedance Spectroscopy
Direct Evaluation of the Electrokinetic Properties of Electrolytes in a Nanochannel using Electrical Impedance Spectroscopy
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DOI：
10.1002/ijch.201400098
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发表时间：
2014-11
影响因子：
3.2
通讯作者：
P. Pungetmongkol;K. Mogi;R. Hatsuki;Takatoki Yamamoto
中科院分区：
文献类型：
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作者：
P. Pungetmongkol;K. Mogi;R. Hatsuki;Takatoki Yamamoto
双电层是在任何液体和固体界面上产生的离子的局部分布。双电层的厚度通常以纳米为单位，因此它在纳米尺度上占主导地位。由于纳米空间的尺寸与双电层的厚度相同数量级，因此纳米空间应该部分/全部填充双电层。因此，研究纳米空间(如纳米孔道和纳米沟道)中双电层中的电动力学对于纳米流体系统中的电学/电化学分析以及分子和纳米粒子的操纵具有重要意义。在这里，我们使用阻抗谱来全面地研究离子浓度和纳米空间的体积对纳米通道中各种离子溶液的电学性质的影响。纳米空间中双电层的电动力学性质和厚度取决于不同离子物种的水化直径、迁移率和离子强度。在特定条件下，如沟道足够窄的情况下，双电层发生重叠，其定性性质符合德拜-休克尔-昂萨格方程。这些结果将对改善纳米通道中分子和颗粒的分析和操作做出重大贡献，从而可能导致纳米流体应用的进一步发展。
An electric double layer is the local distribution of ions created at any liquid and solid interface. The thickness of the electric double layer is typically in nanometers, so that it is dominant in the nanoscale. Because the size of the nanospace is the same order of magnitude as the thickness of the electric double layer, the nanospace should be partially/totally filled with an electric double layer. Therefore, the investigation of the electrokinetics inside the electric double layer in nanospaces, such as nanopores and nanochannels, is very important for electrical/electrochemical analysis and for the manipulation of molecules and nanoparticles in nanofluidic systems. Here, electrical impedance spectroscopy was used to comprehensively investigate how the ionic concentration and the volume of the nanospace influenced the electrical properties of various ionic solutions in a nanochannel. The electrokinetic properties and the thickness of the electric double layer in the nanospace were determined to be dependent on the hydration diameter, mobility, and ionic strength of the various ion species. The electric double layer overlaps under particular conditions, such as with sufficiently narrow channels, and the qualitative properties of this were consistent with the Debye-Huckel-Onsager equation. These results should be a significant contribution to the improvement of the analysis and manipulation of molecules and particles in nanochannels, which could lead to further development in the application of nanofluidics.