Chemically Driven Enhancement of Oxygen Reduction Electrocatalysis in Supported Perovskite Oxides.

Perovskite oxides have the capacity to efficiently catalyze the oxygen reduction reaction (ORR), which is of fundamental importance for electrochemical energy conversion. While the perovskite catalysts have been generally utilized with a support, the role of the supports, regarded as inert toward the ORR, has been emphasized mostly in terms of the thermal stability of the catalyst system and as an ancillary transport channel for oxygen ions during the ORR We demonstrate a novel approach to improving the catalytic activity of perovskite oxides for solid oxide fuel cells by controlling the oxygen-ion conducting oxide supports. Catalytic activities of (La0.8Sr0.2)(0.95)MnO3 perovskite thin-film placed on different oxide supports are characterized by electrochemical impedance spectroscopy and X-ray absorption spectroscopy. These analyses confirm that the strong atomic orbital interactions between the support and the perovskite catalyst enhance the surface exchange kinetics by similar to 2.4 times, in turn, improving the overall ORR activity.