An Investigation of the Electrochemical Activity of (Ba/Sr)FeO3-y Anodes

Abstract

FeOx, SrFeO3-y (SF), and Ba0.5Sr0.5FeO3−y (BSF) were studied for application as fuel oxidation catalysts in solid oxide fuel cells (SOFC) anodes. Electrodes were prepared by impregnation into porous yttria-stabilized zirconia (YSZ), with La0.3Sr0.7TiO3−y (LST) added for electronic conductivity. The electrode impedances decreased dramatically upon addition of SF and BSF and much less when only SrO or FeOx were added. Temperature Programmed Desorption (TPD) of O2 from oxidized BSF showed O2 desorbing between 200 °C and 700 °C, while no O2 desorbed from Fe2O3 below 900 °C. The results, together with thermodynamic analysis, suggest that stabilization of Fe+4 in the perovskite lattice plays an important role in enhancing the catalytic activity of SF and BSF by providing access to a Fe3+/Fe4+ redox couple that can accept oxygen anions from the yttria-stabilized zirconia (YSZ) electrolyte. Oxygen is weakly bound to these sites facilitating its reaction with adsorbed H2.