Electrocatalytic behavior of calcium doped LaFeO 3 as cathode material for solid oxide fuel cell

Abstract

La 1-xCa xFeO 3 (X = 0.0,0.2,0.4, abbreviated as LCF) as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC) was synthesized by new route of glycine nitrate method. LCF materials were characterized by X-ray diffraction (XRD), scanning electron microscopy-energydispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), electrical and electrochemical impedance spectroscopy (EIS). The powder LCFs exhibited single phase with orthorhombic structure, highly porous and small nanoparticles with average size of 200-300 nm. The electrical conductivities of LCFs increased as increasing the Ca content and achieved the maximum electrical conductivity of 148 Scm -1 for La 0.6Ca 0.4FeO 3 (X = 0.4) at 550 °C. The improved conductivity of LCFs could be a promising cathode material for IT-SOFCs. In the impedance analysis of fabricated symmetry cell with the optimized La 0.6Ca 0.4FeO 3 cathode and Ce 0.8Sm 0.2O 3 (SDC) electrolyte, the minimum area specific resistance (ASR) of 0.15 °cm 2 was observed at 850 °C, which may due to the lowest activation energy (1.55 eV), resulting from the reduction of oxygen molecules into oxygen ions. It was found that calcium doping was essential to increase the charge carrier concentration of lanthanum iron oxide materials, resulting in the high conductivity at intermediate temperature. Copyright © 2011 American Scientific Publishers All rights reserved.