Reversible Compositional
Control of Oxide Surfaces
by Electrochemical Potentials

Mutoro, Eva; Crumlin, Ethan
J.; Pöpke, Hendrik; Luerssen, Bjoern; Amati, Matteo; Abyaneh, Majid K.; Biegalski, Michael D.; Christen, Hans M.; Gregoratti, Luca; Janek, Jürgen; Shao-Horn, Yang

doi:10.1021/jz201523y.s001

Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

journal contribution

posted on 2015-12-16, 20:41 authored by Eva Mutoro, Ethan J. Crumlin, Hendrik Pöpke, Bjoern Luerssen, Matteo Amati, Majid K. Abyaneh, Michael D. Biegalski, Hans M. Christen, Luca Gregoratti, Jürgen Janek, Yang Shao-Horn

Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically/ionically conducting, and thus, they have been used in a number of solid-state devices such as solid oxide fuel cells (SOFCs) and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface compositions is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface compositional changes of La_0.8Sr_0.2CoO_3−δ (LSC₁₁₃), (La_0.5Sr_0.5)₂CoO_4±δ (LSC₂₁₄), and LSC₂₁₄-decorated LSC₁₁₃ films (LSC_113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr were found for the LSC_113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites.