International Journal of Hydrogen Energy, Vol.42, No.3, 1724-1735, 2017
Strontium and copper doped LaCoO3: New cathode materials for solid oxide fuel cells?
In the field of solid state electrochemistry, lanthanum cobaltites are very good electronic conductors used as SOFC cathode materials. In this work, Sr and Cu-doped LaCoO3 perovskites (LaCo0.5Cu0.5O3-delta, La0.5Sr0.5Co0.5Cu0.5O3-delta) have been prepared by means of the citrate route procedure and investigated. XRD confirms the formation of the desired phase and no secondary phases are detected. XPS. and EDX results suggest that doping affects cations' surface segregation: lanthanum and copper are surface segregated in the LaCo0.5Cu0.5O3-delta whereas this is not observed in the La0.5Sr0.5Co0.5Cu0.5O3-delta. TPD experiments revealed that doping greatly increases the desoprtion of alpha and beta oxygen species. The oxygen permeability was also determined in order to evaluate mixed ionic and electronic conductivity in addition to the surface activity in oxygen reduction reaction: in particular copper doping was observed to enhance permeability even at rather low temperature (500 degrees C. Finally, electrochemical impedance spectroscopy measurements carried out on a symmetrical half-cell with Ce0.9Gd0.1O2 as electrolyte to characterize the effect of doping on electrochemical properties, revealed that the Cu and Sr doping enhances the performance as SOFC cathode. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.