Novel cobalt-free perovskite PrBaFe1.9Mo0.1O5+δ as a cathode material for solid oxide fuel cells

Fe-based perovskite PrBaFe2O5+delta is inactive toward the oxygen reduction reaction (ORR) due to the sluggish oxygen-ion transport kinetics. Herein, Mo doping is developed as a simple and effective strategy to improve the ORR activity of PrBaFe2O5+delta. Mo-doped PrBaFe1.9Mo0.1O5+delta (PBFMO) is comparatively studied with undoped PrBaFe2O5+delta (PBFO) to reveal the effect of Mo doping on its crystal structure, thermal expansion behavior, electrical and electrochemical properties. PBFMO sample has a tetragonal structure with P4/mmm space group. Pr, Fe, and Mo in PBFMO sample exist as Pr3+/Pr4+, Fe2+/Fe3+, and Mo5+/Mo6+ mixed valence states. Mo doping reduces the average thermal expansion coefficient (TEC) from 18.8 x 10(-6) K-1 down to 14.5 x 10(-6) K-1, which is closer to the TEC of La0.8Sr0.2Ga0.8Mg0.2O3-delta (LSGM) electrolyte. Moreover, Mo doping results in the increment of oxygen vacancy content and thus the enhancement of electrochemical performance. The polarization resistance (Rp) is 0.092 Omega center dot cm(2) at 800 degrees C for PBFMO and is reduced by 27.0% after Mo doping. The peak power density is 0.68 W center dot cm(-2) at 800 degrees C for PBFMO-based single cell. These obtained results indicate Mo doped PBFMO can be a good candidate for cathode material of intermediate temperature SOFC.