Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Chem Phys. 2018 Oct 28;149(16):164701. doi: 10.1063/1.5047550.
The ion distribution of electrolytes near interfaces with dielectric contrast has important consequences for electrochemical processes and many other applications. To date, most studies of such systems have focused on geometrically simple interfaces, for which dielectric effects are analytically solvable or computationally tractable. However, all real surfaces display nontrivial structure at the nanoscale and have, in particular, a nonuniform local curvature. Using a recently developed, highly efficient computational method, we investigate the effect of surface geometry on ion distribution and interface polarization. We consider an asymmetric 2:1 electrolyte bounded by a sinusoidally deformed solid surface. We demonstrate that even when the surface is neutral, the electrolyte acquires a nonuniform ion density profile near the surface. This profile is asymmetric and leads to an effective charging of the surface. We furthermore show that the induced charge is modulated by the local curvature. The effective charge is opposite in sign to the multivalent ions and is larger in concave regions of the surface.
电解质在具有介电对比度的界面附近的离子分布对电化学过程和许多其他应用具有重要影响。迄今为止，大多数此类系统的研究都集中在几何形状简单的界面上，这些界面的介电效应可以通过解析或计算方法求解。然而，所有真实表面在纳米尺度上都显示出非平凡的结构，特别是具有不均匀的局部曲率。我们使用最近开发的高效计算方法，研究了表面几何形状对离子分布和界面极化的影响。我们考虑了由正弦形变形固体表面限定的不对称 2:1 电解质。我们证明，即使表面是中性的，电解质在表面附近也会获得不均匀的离子密度分布。这种分布是不对称的，会导致表面的有效充电。我们还表明，诱导电荷受到局部曲率的调制。有效电荷与多价离子的符号相反，并且在表面的凹面区域更大。
