Turning bad into good: A medium-entropy double perovskite oxide with beneficial surface reconstruction for active and robust cathode of solid oxide fuel cells.

[Display omitted] The cathodes of solid oxide fuel cells (SOFCs) often suffer from detrimental cation segregations and associated impurities poisoning, leading to insufficient electroactivity and poor stability. Here we developed a medium-entropy double perovskite GdBa(Co 1.2 Mn 0.2 Fe 0.2 Ni 0.2 Cu 0.2)O 5-δ (ME-GBCO) for promising SOFC cathode. The increased configuration entropy can effectively tailor the surface composition with in situ formed active BaCoO 3-δ (BCO) species, rather than inert and deleterious BaO x segregation on parent GdBaCo 2 O 5-δ (GBCO) surface. Accordingly, the layered ME-GBCO cathode with beneficial surface reconstruction exhibited not only high oxygen reduction activity but excellent durability against CO 2 impurity, enabling it a very attractive cathode for intermediate temperature SOFCs (IT-SOFCs). Our study provides a new idea for development of efficient and durable cathodes via configurational entropy induced rational surface reconstruction. [ABSTRACT FROM AUTHOR]