Rapid and durable oxygen reduction reaction enabled by a perovskite oxide with self-cleaning surface

The growth of electrochemically inert segregation layers on the surface of solid oxide fuel cell cathodes has become a bottleneck restricting the development of perovskite-structured oxygen reduction cata-lysts. Here, we report a new discovery in which enriched Ba and Fe ions on the near-surface of Nd1/2Ba1/2Co1/3Fe1/3Mn1/3O3_d spontaneously agglomerate into dispersed Ba5Fe2O8 nanoparticles and maintain a highly active and durable perovskite structure on the surface. This unique surface self-cleaning phenomenon is related to the low average potential energy of Ba5Fe2O8, which is grown on the near-surface layer. The electrochemically inert Ba5Fe2O8 segregation layer on the near-surface of the perovskite catalyst achieves self-cleaning by regulating the formation energy of enriched metal oxi-des. This self-cleaned perovskite surface exhibits an ultrafast oxygen exchange rate, high catalytic activity for the oxygen reduction reaction, and good adaptability to the actual working conditions of solid oxide fuel cell stacks. This study paves a new way for overcoming the stubborn problem of perovskite catalyst surface deactivation and enriches the scientific knowledge of surface catalysis.& COPY; 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.