Oxygen vacancy-engineered cobalt-free Ruddlesden-Popper cathode with excellent CO2 tolerance for solid oxide fuel cells

Abstract Developing efficient and durable cobalt-free cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs) is indispensable on account of the sluggish oxygen reduction reaction (ORR). In this work, we report our findings in significantly improved ORR kinetics of (SrEu2)0.9Fe2O7-δ ((SE)0.9F) by introducing a 10% A-site deficiency in SrEu2Fe2O7 (SEF) at the atomic scale. Using this cation deficient strategy, sufficient oxygen vacancy concentration in (SE)0.9F lattice (δ = 0.40) is successfully achieved. Moreover, much improved electrical conductivity and promoted catalytic activity toward the ORR are observed in this new catalyst at intermediate temperatures (550–700 °C), which also offers excellent CO2 resistivity. This work demonstrates an integral role of Ruddlesden-Popper oxides in applying as highly efficient and stable cobalt-free cathodes for IT-SOFCs.