Solution-corrected Constant Potential Model for CO2 Electrocatalysis in Ionic Liquids

TL;DR

This paper introduces a solution-corrected constant potential model (CPM-sol) for simulating CO2 electrocatalysis in ionic liquids, addressing challenges of low dielectric constants and ion distributions, to improve electrolyte design insights.

Contribution

The study develops a novel CPM-sol model that incorporates solution-phase corrections, enhancing the accuracy of simulations for ionic liquids in CO2 electrocatalysis.

Findings

Solution-corrected CPM accurately predicts electrode charge and CO2 distribution.

Interactions in ionic liquids influence ion distribution and electrode surface charge.

Model provides mechanistic insights for electrolyte design in CO2 reduction.

Abstract

The selection of suitable ionic liquids (ILs) is critical for CO2 capture and electrocatalytic conversion into valuable chemical products. The screening process can be enhanced with theoretical simulations that reveal the property-performance relationship of ILs, accelerating the identification of optimal candidates. However, anhydrous ionic liquids exhibit low dielectric constants and high ion concentrations, challenging traditional first-principles calculations. Additionally, the spatial distribution of CO2 in the electric double layer (EDL) plays a crucial role in determining the electrocatalytic activity. This work proposes a solution-corrected constant potential model (CPM-sol) to account for the imbalance between the net charge and the number of electrons on the electrode surface through an implicit consideration of ion distributions. By incorporating solution-phase corrections into the conventional CPM model, we reveal the changes in the Fermi level and charge alongside the reaction process. Furthermore, we systematically investigate the impact of various IL properties on electrode surface charging and CO2 distribution. The theoretical results highlight the critical role of interactions between solution components, forming chain-like structures, in determining their distribution in confined environments and influencing the electrode surface charge. These findings provide insights for mechanism-guided electrolyte design.