Electroconvection near an ion-selective surface with Butler-Volmer kinetics
Electroconvection near an ion-selective surface with Butler-Volmer kinetics
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DOI：
10.1017/jfm.2021.907
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发表时间：
2021-11-11
影响因子：
3.7
通讯作者：
Koch, Donald L.
中科院分区：
文献类型：
--
作者：
Li, Gaojin;Townsend, Alex;Koch, Donald L.
我们采用线性稳定性分析和数值模拟相结合的方法研究了界面动力学对离子选择性表面附近离子传输电流体动力学的影响。电解质-电极界面的有限动力学在许多方面影响离子转移和电对流。在固定形貌的表面上，例如缓慢且稳定的离子沉积或由聚合物膜覆盖的金属表面，有限动力学降低了一维离子扩散/迁移中的电流，增加了电对流不稳定性开始的临界电压，改变了电对流和过限电流的动力学，并增强了界面层内的横向离子扩散。前三种效应是由反应动力学间接引起的，并且可以通过液体电解质两端的有效电压差来表征。相比之下，最后的效果是由动力学和非线性电对流之间的直接相互作用控制。提出了离子输运的标度律和电对流的特征。我们还分析了离子沉积下的表面演变的线性稳定性，发现有限动力学降低了电对流和形态不稳定性的增长率，因此修改了最不稳定模式的波数。
We study the effects of interfacial kinetics on the electro-hydrodynamics of ion transport near an ion-selective surface using a combination of linear stability analysis and numerical simulation. The finite kinetics of the electrolyte-electrode interface affects the ion transfer and electroconvection in many ways. On a surface of fixed topography, such as a metal surface of slow and stable ion deposition or covered by a polymer membrane, the finite kinetics reduces the current in one-dimensional ion diffusion/migration, increases the critical voltage for the onset of the electroconvective instability, changes the dynamics of the electroconvection and the overlimiting current, and enhances the lateral ion diffusion within the interfacial layer. The first three effects are indirectly caused by the reaction kinetics and can be characterized by an effective voltage difference across the liquid electrolyte. In comparison, the last effect is controlled by a direct interplay between kinetics and nonlinear electroconvection. Scaling laws for ion transport and features of electroconvection are proposed. We also analyse the linear stability of a surface which evolves under ion deposition and find that the finite kinetics decreases the growth rate of both electroconvective and morphological instabilities and therefore modifies the wavenumber of the most unstable mode.