Quantitative characterization of Cr-adsorption on CeO2, pure and doped BaCeO3 and its impact on the electrochemical performance of Ce containing complex oxides

摘要

Quantitative analysis of Cr-adsorption from a gas phase on CeO2, pure and doped BaCeO3 was performed in combination with surface techniques and electrochemical impedance spectroscopy. The Cr-adsorption on BaCeO3 is 3 times higher than on CeO2 and it increases by 12-25% on In doping in Ba(Ce1-xInx)O-3 (x = 0.1-0.3) in the temperature range of 600 -700 degrees C. These perovskites adsorb chromium with the formation of a multi-phase surface layer containing BaCr6+O4 and cerium oxide. Coexistence of small fractions of Cr3+ and Cr5+ cations in the surface layer was identified by X-ray photoelectron spectroscopy. The thickness of the surface layer and its morphology vary with temperature, affecting the conductivity of Ce containing perovskites below 700 degrees C. BaCrO4 exhibits under air noticeably larger anisotropic thermal expansion than BaCeO3. The results indicate that high tolerance to Cr-gaseous species should be considered as an important criterion for further development of materials for proton-conducting SOFCs. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.