Analytical Interfacial Layer Model for the Capacitance and Electrokinetics of Charged Aqueous Interfaces.
Analytical Interfacial Layer Model for the Capacitance and Electrokinetics of Charged Aqueous Interfaces.
复制标题
DOI：
10.1021/acs.langmuir.7b04171
复制
发表时间：
2018-03
期刊：
影响因子：
--
通讯作者：
Y. Uematsu;R. Netz;D. J. Bonthuis
中科院分区：
文献类型：
--
作者：
Y. Uematsu;R. Netz;D. J. Bonthuis
我们构建了一个分析模型来解释亚纳米宽的界面层对固体电解质界面的微分电容和电渗迁移率的影响。界面层被纳入泊松-玻尔兹曼和斯托克斯方程使用盒模型的介电性能，粘度，和平均力的离子势。我们计算的微分电容和电渗迁移率作为表面电荷密度和盐浓度的函数，无论有和没有离子之间的空间相互作用。我们比较了我们的理论模型的结果与实验数据的各种系统（石墨和金属银的电容和氧化钛和银的电渗数据）。银的微分电容作为盐度和表面电荷密度的函数被我们的理论很好地再现，使用界面层的宽度或平均力的离子势作为唯一的拟合参数。然而，石墨的微分电容需要额外的碳电容来解释实验数据。我们的理论产生了幂律依赖的电渗迁移率的表面电荷密度高的表面电荷，再现实验数据，使用从分子动力学模拟和拟合的界面参数提取的界面参数。最后，我们研究了不同类型的流体动力学边界条件的幂律行为的电渗流动性，表明一个有限的粘度层解释的实验数据比通常的流体动力学滑移边界条件。因此，我们的分析模型，使我们能够提取的亚纳米宽的界面层通过拟合宏观实验数据的属性。
We construct an analytical model to account for the influence of the subnanometer-wide interfacial layer on the differential capacitance and the electro-osmotic mobility of solid-electrolyte interfaces. The interfacial layer is incorporated into the Poisson-Boltzmann and Stokes equations using a box model for the dielectric properties, the viscosity, and the ionic potential of mean force. We calculate the differential capacitance and the electro-osmotic mobility as a function of the surface charge density and the salt concentration, both with and without steric interactions between the ions. We compare the results from our theoretical model with experimental data on a variety of systems (graphite and metallic silver for capacitance and titanium oxide and silver iodide for electro-osmotic data). The differential capacitance of silver as a function of salinity and surface charge density is well reproduced by our theory, using either the width of the interfacial layer or the ionic potential of mean force as the only fitting parameter. The differential capacitance of graphite, however, needs an additional carbon capacitance to explain the experimental data. Our theory yields a power-law dependence of the electro-osmotic mobility on the surface charge density for high surface charges, reproducing the experimental data using both the interfacial parameters extracted from molecular dynamics simulations and fitted interfacial parameters. Finally, we examine different types of hydrodynamic boundary conditions for the power-law behavior of the electro-osmotic mobility, showing that a finite-viscosity layer explains the experimental data better than the usual hydrodynamic slip boundary condition. Our analytical model thus allows us to extract the properties of the subnanometer-wide interfacial layer by fitting to macroscopic experimental data.