Surface-decoration of perovskites can strongly affect the oxygen reduction activity, and therefore is a new and promising approach to improve SOFC cathode materials. In this study, we demonstrate that a small amount of secondary phase on a (001) La 0.8Sr 0.2CoO 3-δ (LSC) surface can either significantly activate or passivate the electrode. LSC (001) microelectrodes prepared by pulsed laser deposition on a (001)-oriented yttria-stabilized zirconia (YSZ) substrate were decorated with La-, Co-, and Sr-(hydr)oxides/carbonates. "Sr"-decoration with nanoparticle coverage in the range from 50% to 80% of the LSC surface enhanced the surface exchange coefficient, k q, by an order of magnitude while "La"- decoration and "Co"-decoration led to no change and reduction in k q, respectively. Although the physical origin for the enhancement is not fully understood, results from atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy suggest that the observed k q enhancement for "Sr"-decorated surfaces can be attributed largely to catalytically active interface regions between surface Sr-enriched particles and the LSC surface. © 2011 The Royal Society of Chemistry.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported in part by DOE (SISGR DE-SC0002633) and King Abdullah University of Science and Technology. E. Mutoro is grateful for financial support from the German Research Foundation (DFG research scholarship). The authors 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 PLD 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. The authors thank Prof. C. Ross (MIT) for the usage of PLD.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.