(Invited) Bridging the Gap between the Physics and Chemistry of Electric Double Layer

Abstract

Classical models of electric double layer (EDL) are mostly concerned with ion distributions and their responses to the surface potential that can be regulated by changing either the voltage or the extent of surface ionization. With the help of adjustable parameters, classical EDL models are able to describe diverse physical phenomena including EDL capacitance and ion transport in good agreement with experimental measurements. However, major challenges remain in understanding chemical reactions within EDL important for the rational design and optimization of electrochemical processes such as energy storage and electrocatalysis. In this talk, I will present a molecular-thermodynamic model to predict the charging behavior of ionizable surfaces under various solution conditions. If a solid is non-conductive, the surface reactions can be reliably described with a Langmuir-type model coupled with liquid-state methods to account for the local thermodynamic non-ideality. When a solid is conductive, however, the electronic properties of different surface sites are intrinsically coupled with each other leading to highly correlated surface reactions. While the brute-force prediction of chemical equilibrium at an electrified surface is computationally prohibitive, a combination of the first-principles calculations and coarse-grained modeling provides complemental information that may be useful for diverse electrochemical applications.