Perovskites are used to promote the kinetics of oxygen electrocatalysis in solid oxide fuel cells and oxygen permeation membranes. Little is known about the surface structure and chemistry of perovskites at high temperatures and partial oxygen pressures. Combining in situ X-ray reflectivity (XRR) and in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we report, for the first time, the evolution of the surface structure and chemistry of (001)-oriented perovskite La0.8Sr0.2CoO 3-δ (LSC113) and (La0.5Sr 0.5)2CoO4+δ (LSC214)-decorated LSC113 (LSC113/214) thin films as a function of temperature. Heating the (001)-oriented LSC113 surface leads to the formation of surface LSC214-like particles, which is further confirmed by ex situ Auger electron spectroscopy (AES). In contrast, the LSC113/214 surface, with activities much higher than that of LSC 113, is stable upon heating. Combined in situ XRR and APXPS measurements support that Sr enrichment may occur at the LSC113 and LSC214 interface, which can be responsible for its markedly enhanced activities. © 2013 American Chemical Society.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported in part by the DOE (SISGR DESC0002633) and King Abdullah University of Science and Technology. The authors would like to thank the King Fahd University of Petroleum and Minerals in Dharam, Saudi Arabia, for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM. The Advanced Photon Source and the Advanced Light Source are supported by the Director, Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contracts DE-AC02-06CH11357 and DE-AC02-05CH11231, respectively. The PLD preparation performed was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.