A-site deficient Fe-based double perovskite oxides PrxBaFe2O5+δ as cathodes for solid oxide fuel cells

Abstract

In this work, Pr-deficiency is presented here as an effective strategy to promote the electrochemical properties of Pr x BaFe 2 O 5+δ (Pr x BF, x = 1.00, 0.97, 0.93, 0.90) cathodes for solid oxide fuel cell (SOFC). The Pr x BF cathode materials were prepared by a sol-gel method. The crystal structure results show that the Pr x BF (x = 1.00) is double-perovskite phase with orthorhombic structure and the Pr x BF (x = 0.97, 0.93, 0.90) is tetragonal perovskite structure. Introduction of Pr-deficiency in Pr x BF oxides causes the decrease of oxygen content. The average TEC values (30–850 °C) for Pr x BF are mainly concentrated between 15.29 and 15.95 × 10 −6 K −1 . In comparison to the parent PrBaFe 2 O 5+δ oxides, the Pr-deficiency cathodes significantly enhance the electrochemical catalytic activity while maintain the lower thermal expansion coefficient. Among the series of Pr x BF cathodes, the Pr 0.93 BF sample obtains the lowest polarization resistance. The fitted result of impedance spectra for Pr 0.93 BF cathode indicates that the charge transfer process in the high frequency plays a more dominant role in the oxygen reduction reaction. Furthermore, the Pr 0.93 BF electrode exhibits a good tolerance to CO 2 . The power density of an anode supported single cell with Pr 0.93 BF cathode achieved 967 mW cm −2 at 700 °C. Preliminary results suggest that Pr x BF oxides are expected to be promising candidates for cathode in SOFC. • The Pr x BaFe 2 O 5+δ (Pr x BF) cathode materials were synthesized by a sol-gel method. • The TEC values of P x BF are concentrated between 15.29 and 15.95 × 10 −6 K −1 . • The Pr 0.93 BF sample shows the lowest polarization resistance. • The peak power densities of Pr 0.93 BF cathode are 967 mW cm −2 at 700 °C.