Configuration entropy tailored beneficial surface segregation on double perovskite cathode with enhanced Cr-tolerance for SOFC

The stability of solid oxide fuel cells (SOFCs) cathodes is often severely damaged by impurity poisonings from Cr vapors. Here we report a medium entropy GdBa(Mn0.2Fe0.2Co1.2Ni0.2Cu0.2)O5+δ (ME-GBCO) double perovskite cathode, which exhibits remarkably improved Cr-tolerant ability. The polarization resistance (Rp) of GBCO increases from ∼0.44 to ∼0.70 Ω cm2 after 20 h exposure to Cr in air at 700 °C. In contrast, Rp value of ME-GBCO cathode increases from ∼0.16 to ∼0.24 Ω cm2 under the same condition. The enhanced operational stability is attributed to the in situ formed BaCoO3-δ (BCO) nanoparticles on ME-GBCO surface, which is very inactive to Cr vapors. This work highlights that the configuration entropy modulation is an effective avenue for surface engineering and for the development of robust cathode materials for SOFCs.