Oxido-reduction properties of La0.7Sr0.3Co0.8Fe0.2O3-δ perovskite oxide catalyst

The oxido-reduction of La0.7Sr0.3Co0.8Fe0.2O3-delta (LSCF7382) perovskite oxide catalyst was studied using O-2 thermodesorption and H-2 temperature-programmed reduction techniques as well as cyclic voltammetry performed on LSCF7382 thin film deposited on gadolinia doped ceria solid electrolyte. The O-2-TPD profile of the attrited powder used for thin film elaboration evidenced two types of desorbed oxygen; i.e. weakly adsorbed oxygen species and lattice oxygen. The annealing treatment decreased the amount of weakly adsorbed oxygen. H-2-TPR and cyclic voltammetry evidenced two reduction processes that retained the perovskite structure in LSCF7382. They were tentatively assigned to the successive reduction of Co4+ to Co3+ and Co2+. The anodic peak observed on the cyclic voltammograms at positive overpotentials could be related to the phenomenom of oxygen back-spillover from the triple phase boundary to the LSCF7382/gas interface. (C) 2010 Elsevier BM. All rights reserved.