Continuum models of the electrochemical diffuse layer in electronic-structure calculations

TL;DR

This paper critically compares continuum electrolyte models coupled with first-principles calculations to accurately predict electrochemical interface properties, highlighting the importance of model features like dielectric cavity parameterization.

Contribution

It provides a systematic evaluation of continuum diffuse-layer models for electrochemical interfaces, validating their effectiveness against experimental data.

Findings

Size-modified Poisson-Boltzmann model reproduces main experimental trends.

Dielectric cavity parameterization significantly affects capacitance calculations.

Continuum models can effectively describe electrolyte screening in first-principles simulations.

Abstract

Continuum electrolyte models represent a practical tool to account for the presence of the diffuse layer at electrochemical interfaces. However, despite the increasing popularity of these in the field of materials science it remains unclear which features are necessary in order to accurately describe interface-related observables such as the differential capacitance (DC) of metal electrode surfaces. We present here a critical comparison of continuum diffuse-layer models that can be coupled to an atomistic first-principles description of the charged metal surface in order to account for the electrolyte screening at electrified interfaces. By comparing computed DC values for the prototypical Ag(100) surface in an aqueous solution to experimental data we validate the accuracy of the models considered. Results suggest that a size-modified Poisson-Boltzmann description of the electrolyte solution is sufficient to qualitatively reproduce the main experimental trends. Our findings also highlight the large effect that the dielectric cavity parameterization has on the computed DC values.