Joint Density-Functional Theory of the Electrode-Electrolyte Interface: Application to Fixed Electrode Potentials, Interfacial Capacitances, and Potentials of Zero Charge

TL;DR

This paper introduces a joint density-functional theory approach for accurately modeling electrochemical interfaces, enabling computation of key electrochemical properties like capacitance and zero charge potentials with minimal additional computational cost.

Contribution

The work presents a new, efficient functional within density-functional theory that captures electrochemical phenomena and interfaces, bridging microscopic calculations with experimental observables.

Findings

Successfully models electrochemical double layer regions

Accurately predicts interfacial capacitance values

Determines potentials of zero charge for various metals

Abstract

This work explores the use of joint density-functional theory, a new form of density-functional theory for the ab initio description of electronic systems in thermodynamic equilibrium with a liquid environment, to describe electrochemical systems. After reviewing the physics of the underlying fundamental electrochemical concepts, we identify the mapping between commonly measured electrochemical observables and microscopically computable quantities within an, in principle, exact theoretical framework. We then introduce a simple, computationally efficient approximate functional which we find to be quite successful in capturing a priori basic electrochemical phenomena, including the capacitive Stern and diffusive Gouy-Chapman regions in the electrochemical double layer, quantitative values for interfacial capacitance, and electrochemical potentials of zero charge for a series of metals. We explore surface charging with applied potential and are able to place our ab initio results directly on the scale associated with the Standard Hydrogen Electrode (SHE). Finally, we provide explicit details for implementation within standard density-functional theory software packages at negligible computational cost over standard calculations carried out within vacuum environments.