Probing Zr Substituting Effects on the Oxygen Reduction Reaction of Fe-Based Double Perovskite Cathodes for Solid Oxide Fuel Cells

The mixed ionic and electronic conductor (MIEC), as a classical family of high-performance cathode materials, is essential for ensuring the low-temperature operation performance and high efficiency of solid oxide fuel cells. The Fe-based double perovskites get the advantages of low cost, good thermal compatibility with the electrolyte, and good high-temperature stability, showing good application promise. However, due to the unsatisfactory electrochemical properties, Fe-based double perovskite MIECs are generally not sufficiently active for the oxygen reduction reaction. Herein, the consequences indicate that Zr-substitution of the Fe sites in the NdBaFe₂O_6-δ(NBF) lattice can obtain a higher oxygen vacancy concentration and a more high-lying position of the O p-band center simultaneously. Then, the Zr-doped NBF cathode obtains a higher oxygen-ion diffusion and oxygen surface exchange coefficients. The lower polarization resistance for NdBaFe_1.9Zr_0.1O_6-δmeasured at 700 °C is 0.066 ω·cm²compared to 0.104 ω·cm²for NBF.