Controlling bulk electrostatics in electrolytes by surface polarization

Abstract

The benchmark theory of hydration forces that relies on the phenomenological expressions developed by Marčelja and Radić (MR) has recently been revived by experimental, computational, and theoretical advances. Here, we consider the effect of surface polarization on electrolytes in a slab geometry by combining the MR approach to polarization with Poisson–Boltzmann theory. Due to the coupling of bulk and surface fields, not only is the electrostatics modified by polarization, but maybe even more importantly, vice versa: a finite polarization at the wall is sufficient to generate a finite electrostatic potential even in the absence of net charges on the wall. We determine the polarization and electrostatic potential profiles and the free energy of the system. Our results show that the presence of surface polarization alone suffices to imprint the bulk structural properties on the electrostatic field in an electrolyte.