Integrating Cation Disordering With Surface Tailoring via Sn/In Co‐Doping for High‐Performance Perovskite Cathode

ABSTRACT The development of stable, durable cathodes with high oxygen reduction reaction (ORR) activity remains a critical challenge in solid oxide fuel cell (SOFC) research. This work employs a Sn‐In co‐doping strategy to synthesize a cathode material with the nominal composition Ba(Co 0.7 Fe 0.3 ) 0.8 (Sn 0.5 In 0.5 ) 0.2 O 3‐δ . The co‑doping strategy transforms the material structure into a more symmetric cubic phase (Pm‐3m) and significantly enhances its oxygen vacancy concentration along with ORR catalytic activity. Indium incorporation serves to generate abundant oxygen vacancies, whereas Density Functional Theory (DFT) calculations predict that Sn doping reduces the oxygen vacancy formation energy by modulating the local electronic structure and selective M‐O (M = Co, Fe) bond weakening, thereby facilitating ion migration. These properties endow the material with excellent ORR activity, achieving an impedance as low as 0.014 Ω·cm 2 at 650°C and a power density of more than 1.4 W/cm 2 in an anode‐supported single cell. This study provides a valuable insight for further exploration of In‐based materials in SOFC cathode development.