A Highly Efficient Multi-phase Catalyst Dramatically Enhances the Rate of Oxygen Reduction

This work demonstrates that a multi-phase catalyst coating (similar to 30 nm thick), composed of BaCoO3-x (BCO) and PrCoO3-x (PCO) nanoparticles (NPs) and a conformal PrBa0.8Ca0.2CO2O5+delta (PBCC) thin film, has dramatically enhanced the rate of oxygen reduction reaction (ORR). When applied to a state-of-theart La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode in a solid oxide fuel cell (SOFC), the catalyst coating reduced the cathodic polarization resistance from 2.57 to 0.312 Omega cm(2) at 600 degrees C. Oxygen molecules adsorb and dissociate rapidly on the NPs due to enriched surface oxygen vacancies and then quickly transport through the PBCC film, as confirmed by density functional theory-based computations. The synergistic combination of the distinctive properties of the two separate phases dramatically enhances the ORR kinetics, which is attractive not only for intermediate-temperature SOFCs but also for other types of energy conversion and storage systems, including electrolysis cells and membrane reactors for synthesis of clean fuels.