Electric Double Layer at the Metal-Oxide/Electrolyte Interface

TL;DR

This paper reviews the physical chemistry and atomistic modeling of the electric double layer at metal-oxide/electrolyte interfaces, emphasizing experimental techniques and density-functional theory simulations.

Contribution

It provides a comprehensive overview of experimental and theoretical approaches to understanding the protonic double layer at metal-oxide/electrolyte interfaces.

Findings

Summarizes experimental methods for EDL characterization.

Highlights density-functional theory-based molecular dynamics simulations.

Discusses future directions in EDL research.

Abstract

Metal-oxide surfaces act as both Br{\o}nsted acids and bases, which allows the exchange of protons with the electrolyte solution and generates either positive or negative proton charges depending on the environmental pH. These interfacial proton charges are then compensated by counter-ions from the electrolyte solution, which leads to the formation of the electric double layer (EDL). Because the EDL plays a crucial role in electrochemistry, geochemistry and colloid science, understanding the structure-property relationship of the EDL in metal-oxide systems from both experimental and theoretical approaches is necessary. This chapter focuses on the physical chemistry of the protonic double layer at the metal-oxide/electrolyte interface. In particular, determinations of the EDL capacitance and the double-layer potential from potentiometric titration experiments, electrochemical methods, surface-sensitive vibrational spectroscopy and X-ray photoelectron spectroscopy are summarized. This is followed by discussions from the atomistic modelling aspect of the EDL, with an emphasis on the density-functional theory-based molecular dynamics simulations. A conclusion and outlook for future works on this topic are also given.