An innovative efficient oxygen electrode for SOFC: Pr6O11 infiltrated into Gd-doped ceria backbone

Abstract

The praseodymium oxide, Pr6O11, is regarded as a potential electrocatalyst for the oxygen reduction reaction. Its mixed conductivity properties are characterized. At 600 °C the oxygen diffusion coefficient value is as high as 3.4 × 10−8 cm2 s−1, and that of the surface exchange coefficient is 5.4 × 10−7 cm s−1, which supposes excellent electrocatalytic properties. The measured electronic conductivity is high enough for using this material as a SOFC cathode. Herein, praseodymium nitrate is infiltrated into Gd doped ceria (GDC) backbone and fired at 600 °C to form a composite oxygen electrode Pr6O11/GDC. Electrochemical measurements show very low polarization resistance, Rp = 0.028 Ω cm2 at 600 °C. A single cell made of a commercial Ni-YSZ/YSZ half cell and of the infiltrated cathode is able to deliver a maximum power density of 825 mW cm−2 at 600 °C. Ageing of this cell for 840 h, at 600 °C and 0.5 A cm−2, shows a degradation rate lower than 1%.