Magnesium oxide as synergistic catalyst for oxygen reduction reaction on strontium doped lanthanum cobalt ferrite

MgO has been demonstrated to have positive effects on the oxygen reduction reaction (ORR) at the strontium doped lanthanum cobalt ferrite (LSCF) cathode for solid oxide fuel cells. MgO particles, which were prepared by the infiltration technique using magnesium nitrate as the precursor, are compatible with LSCF under the experimental conditions for electrode fabrication. Electrical conductivity relaxation investigation demonstrated that the chemical oxygen surface exchange coefficient at 750 °C can be improved by a factor up to 2.4 through coating LSCF surface with MgO particles. Electrochemical impedance analysis showed that the area specific interfacial polarization resistance can be obviously reduced, such as from 0.49 Ω cm2 to 0.31 Ω cm2 at 650 °C when a porous LSCF electrode supported on samaria-doped ceria electrolyte was infiltrated with 1.01 wt% MgO particles. Distribution of relaxation time (DRT) analysis suggested that the resistance reduction is associated with the charge transfer process. Thus, MgO can enhance ORR on LSCF electrocatalyst, like the previously reported alkaline earth metal compounds of BaCO3, SrCO3 and CaO.