CO2-induced reconstruction for ORR-enhanced solid oxide fuel cell cathode

Solid oxide fuel cell (SOFC) cathode must be highly active and durable for electrochemical oxygen reduction reaction (ORR). Here, we demonstrate a CO2-induced reconstruction strategy to build an oxygen incorporative but robust BaCO3 shell for a self-assembled composite cathode from simple BaFeO3-δ perovskite (noted as re-BF), leading to the enhanced ORR activity, durability, and thermomechanical compatibility. The heterostructure beneath the BaCO3 shell consists of a BaFeO3 phase and a BaFe2O4 phase, of which BaFeO3 sustains the re-BF with good bulk oxygen transportation. The BaFe2O4 phase is stable with low thermal expansion coefficient, serving as a reinforced phase to re-BF for better chemical/morphological integrity. This new re-BF cathode shows good durability and a low area-specific resistance (ASR) of 0.013 Ω cm2, about only one-third of pristine BaFeO3-δ (0.041 Ω cm2) at 650 °C. This method can also be extended to other perovskite materials to develop an active catalyst for SOFC cathode.