Implicit Solvation Methods for Catalysis at Electrified Interfaces

TL;DR

This paper reviews implicit solvation methods used in atomic-scale simulations of electrochemical interfaces, emphasizing their role in modeling the double layer and electrode polarization in electrocatalysis, while highlighting current challenges in parameterization.

Contribution

It provides a comprehensive overview of implicit solvation techniques tailored for electrified interfaces, focusing on their application in ab initio thermodynamics and addressing specific challenges.

Findings

Implicit solvation effectively models the double layer at electrified interfaces.

It enables simulation of electrode polarization beyond supercell limitations.

Lack of reference data hampers parameterization of the methods.

Abstract

Implicit solvation is an effective, highly coarse-grained approach in atomic-scale simulations to account for a surrounding liquid electrolyte on the level of a continuous polarizable medium. Originating in molecular chemistry with finite solutes, implicit solvation techniques are now increasingly used in the context of first-principles modeling of electrochemistry and electrocatalysis at extended (often metallic) electrodes. The prevalent ansatz to model the latter electrodes and the reactive surface chemistry at them through slabs in periodic boundary condition supercells brings its specific challenges. Foremost this concerns the diffculty to describe the entire double layer forming at the electrified solid-liquid interface (SLI) within supercell sizes tractable by commonly employed density-functional theory (DFT). We review liquid solvation methodology from this specific application angle, highlighting in particular its use in the widespread {\em ab initio} thermodynamics approach to surface catalysis. Notably, implicit solvation can be employed to mimic a polarization of the electrode's electronic density under the applied potential and the concomitant capacitive charging of the entire double layer beyond the limitations of the employed DFT supercell. Most critical for continuing advances of this effective methodology for the SLI context is the lack of pertinent (experimental or high-level theoretical) reference data needed for parametrization.