Nd-induced defect and lattice engineering in BNCBF perovskite cathodes for high-performance intermediate-temperature SOFCs

Intermediate-temperature solid oxide fuel cells require cathode with fast oxygen reduction kinetics, tunable defect chemistry, and high stability. Although BaFeO 3 -based perovskites exhibit promising catalytic activity and triple conductivity, their lattice stability and surface reaction kinetics require further improvement. Herein, a series of Ba 1-x Nd x Ce 0.2 Bi 0.1 Fe 0.7 O 3−δ (BNCBFx) cathodes are developed. The effects of Nd incorporation on the crystal structure, oxygen defect behavior, and electrochemical performance are systematically investigated. The single cell with BNCBF50 cathode delivers a low polarization resistance of 0.04 Ω cm 2 and a peak power density of 1730 mW cm −2 at 700 °C. Combined valence-state analysis and theoretical calculations reveal that Nd incorporation promotes charge compensation and oxygen vacancy formation, which in turn enhances oxygen adsorption/activation and lowers the proton migration barrier. Consequently, an ideal balance among lattice stability, oxygen vacancies, and surface catalysis is achieved, providing a rational strategy for designing high-performance SOFC cathodes via defect engineering.