First-principles study of oxygen reduction reaction on Pd-doped LaxSr1-xCoyFe1-yO3-δ cathodes of solid oxide fuel cells

Abstract

Surface adsorption, adissociation and bulk migration behaviors of oxygen species on Pd-doped LSCF (LSCF-Pd) cathode are investigated with first-principle method. Results show that Pd-doping reduces largely the formation energy of oxygen vacancy on LSCF-Pd surface. Oxygen adsorption abilities on LSCF and LSCF-Pd surfaces are comparable (1.30 vs 1.32 eV) with oxygen vacancies, while on perfect LSCF surface that is weakened by Pd-doping. The minimum dissociation energy barriers of oxygen molecules on LSCF and LSCF-Pd surface are 0.48 and 0.34 eV, respectively, which indicates that Pd-doping improves oxygen dissociation behaviors. Also, migration barriers of oxygen vacancy in LSCF-Pd bulk is comparable to that in LSCF bulk. The improved mechanisms can be attributed to the lowered formation energy of oxygen vacancy, oxygen dissiciation barriers of innate oxygen defect and migration barriers of oxygen vacancy in the bulk by Pd-doping.