Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

Knowing and controlling the surface composition of perovskite is crucial to enhance device performance. We demonstrated 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 La0.8Sr0.2CoO(3–δ) (LSC113), La0.5Sr0.5)2CoO(4±δ) (LSC214), and LSC214-decorated LSC113 films (LSC113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr was found for the LSC113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites.