Hydrodynamics within the Electric Double Layer on slipping surfaces

TL;DR

This study uses Molecular Dynamics simulations to explore how surface wettability influences the behavior of the electric double layer and electrokinetic phenomena, revealing distinct dynamics on wetting versus non-wetting surfaces.

Contribution

It provides new insights into the role of wettability and slippage in EDL dynamics, clarifying the nature of the Stern layer and Zeta potential.

Findings

Wettability determines the mobility of the Stern layer.

Slippage amplifies the Zeta potential on non-wetting surfaces.

Electric properties dominate EDL dynamics on wetting surfaces.

Abstract

We show, using extensive Molecular Dynamics simulations, that the dynamics of the electric double layer (EDL) is very much dependent on the wettability of the charged surface on which the EDL develops. For a wetting surface, the dynamics, characterized by the so-called Zeta potential, is mainly controlled by the electric properties of the surface, and our work provides a clear interpretation for the traditionally introduced immobile Stern layer. In contrast, the immobile layer disappears for non-wetting surfaces and the Zeta potential deduced from electrokinetic effects is considerably amplified by the existence of a slippage at the solid substrate.