Asymmetric electrolytes near structured dielectric interfaces

TL;DR

This study uses advanced computational methods to explore how nanoscale surface structures influence ion distributions and surface polarization in asymmetric electrolytes, revealing curvature-dependent effective surface charging.

Contribution

It introduces a novel computational approach to analyze the impact of complex surface geometries on electrolyte behavior near dielectric interfaces.

Findings

Ion density profiles are nonuniform and asymmetric near structured surfaces.

Surface curvature modulates the induced charge and effective surface charging.

Even neutral surfaces can acquire a nonzero effective charge due to geometry effects.

Abstract

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, 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.