Interfaces between Oxides and Ionic Liquid Investigated by Vacuum Electrochemistry Approach

Abstract

We introduce our state-of-the art of “vacuum electrochemistry” to investigation of the interfaces between oxides and ionic liquid (IL). Pulsed laser deposition (PLD) has been one of the powerful and sophisticated techniques to realize nanoscale preparation of high-quality oxide thin films. On the other hand, electrochemistry is a simple, very sensitive, and non-destructive analysis technique for solid-liquid interfaces. To ensure the reproducibility in experiment of the interfaces of such epitaxial oxide films, as well as bulk oxide single-crystals, with IL, we employ a home-built PLD-electrochemical (EC) system with IL as an electrolyte. The system allows one to perform all-in-vacuum experiments from preparation of well-defined oxide electrode surfaces to their electrochemical analyses. The topics include electrochemical evaluations of the oxide's own properties, such as carrier density and dielectric constant, and the interfacial properties of oxides in contact with IL, such as flat band potential and electric double layer (EDL) capacitance.