Monte Carlo simulation of the planar discrete double layer for neutrally charged interfaces

Abstract

A Monte Carlo simulation study on the charge distribution and structure of the electric double layer (EDL) that forms between two planar interfaces is presented, using a model electrolyte of monovalent hard-sphere ions and confining walls composed of two discrete and sign-alternating charge distributions. Symmetric and asymmetric plate-plate orientations, along with uncharged walls, are considered. Results are presented for effective wall-ion correlation functions and local integrated charge in the subvolumes defined by the charge domains on the plates. We report that, in the presence of multifaceted charged surfaces, the ions between the walls exhibit complex and rich behavior, with the formation of an EDL next to the charged domains of the interface, and having density profiles of counterions and coions that are established as function of the nature and configuration of the charged strips. These profiles present a structural frustration that renders the subvolumes with a net charge, in contrast to the null net charge from profiles next to a uniformly charged surface. Finally, with proper scaling, the integrated charge follows closely a master curve for each wall-wall configuration. Such phenomenology is visible in the regime of low and high surface charge.