Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

Abstract
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 (LSC 113), (La 0.5Sr 0.5) 2CoO 4±δ (LSC 214), and LSC 214-decorated LSC 113 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. © 2011 American Chemical Society.

Citation
Mutoro E, Crumlin EJ, Pöpke H, Luerssen B, Amati M, et al. (2012) Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials. The Journal of Physical Chemistry Letters 3: 40–44. Available: http://dx.doi.org/10.1021/jz201523y.

Acknowledgements
This work was supported in part by DOE (SISGR DESC0002633), King Abdullah University of Science and Technology, and the King Fahd University of Petroleum and Minerals in Dharam (through the Center for Clean Water and Clean Energy at MIT and KFUPM). The German Research Foundation is acknowledged for financial support (E.M.: DFG research scholarship; H.P., B.L., and J.J.: LU1480/1-1 and JA648/17-1). The sample preparation performed at the Center of Nanophase Materials Sciences was sponsored by the Scientific User Facilities Division, Office of Basic Energy Science, U.S. DOE.

Publisher
American Chemical Society (ACS)

Journal
The Journal of Physical Chemistry Letters

DOI
10.1021/jz201523y

Permanent link to this record