Effect of nonequivalent substitution of Pr3+/4+ with Ca2+ in PrBaCoFeO5+δ as cathodes for IT-SOFC

We used a Ca doping strategy with PrBaCoFeO5+delta (PBCF) to prepare a novel double-perovskite Pr1-xCaxBaCoFeO5+delta (PCBCF). x = 0.05 and x = 0.1 samples exhibited a single phase with layered double-perovskite structure, combined with good chemical compatibility with common electrolyte materials. X-ray photoelectron spectroscopy profiles of PCBCF were compared to that of PBCF to detect differences in oxidation states. The substitution of Ca2+ for Pr ions in PCBCF effectively reduces the thermal expansion coefficient and material costs. Though the introduction of Ca2+ reduced the electrical conductivity, it improved the oxygen catalytic activity. The improved electrochemical performance was attributed to the increased oxygen vacancy concentration in the lattice. The optimal composition x = 0.1 cathode exhibited the best catalytic activity and durability. The polarization impedance and maximum power density of the 0.1 cathode were 0.027 Omega cm(2) and 728 mW cm(-2) at 800 degrees C, respectively. Distribution of relaxation time analysis demonstrated that the 0.1 cathode electrochemical reactions under oxygen partial pressures involved at least three processes and confirmed that the transfer process of oxide ions and charge transfer process are the major rate-determining steps of the oxygen reduction reaction. The combination of experimental and analysis results indicated that the 0.1 sample has considerable potential as part of a cathode for application in intermediate-temperature solid oxide fuel cells.

Automated summary

By utilizing a Ca doping strategy, a novel double-perovskite material Pr1-xCaxBaCoFeO5+delta (PCBCF) was successfully prepared, showing promising electrochemical performance for oxygen reduction reactions in intermediate-temperature solid oxide fuel cells. The introduction of Ca2+ effectively reduced thermal expansion coefficient and material costs, while improving oxygen catalytic activity. The optimal composition x = 0.1 demonstrated the best catalytic activity and durability, making it a potential candidate for cathode applications.