High entropy double perovskite cathodes with enhanced activity and operational stability for solid oxide fuel cells.

Rare-earth site high entropy double perovskite oxides with different molar ratios have been evaluated as the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). The effect of configuration entropy on crystal structure, electrical conductivity, electrochemical performance and stability are investigated. Our results reveal that the activity of all high entropy oxides show enhanced electrochemical activity. Among them, the equimolar one (HEO) exhibits the highest activity with a low polarization resistance of 0.05 Ω cm2 at 700 °C. Moreover, it exhibits excellent stability in the CO 2 -containing atmosphere. The enhanced activity and operational stability can be attributed to reduced surface Ba segregation and the formation of active and robust BaCoO 3-δ nanoparticles on HEO surface, rather than BaCO 3 and Co 3 O 4 phases. This work indicates that configurational entropy engineering is very effective for rational surface composition regulation. [ABSTRACT FROM AUTHOR]