Novel cobalt-free Pr2Ni1-xNbxO4 (x = 0, 0.05, 0.10, and 0.15) perovskite as the cathode material for IT-SOFC.

The cobalt-free cathode materials with high activity is critical to the commercial application of medium temperature solid oxide fuel cells (IT-SOFC). Herein, a series of cobalt-free Nb-doped Pr 2 Ni 1- x Nb x O 4 (x = 0, 0.05, 0.10, and 0.15) perovskite oxides were successfully prepared, and the effects of Nb-doping on the structure, thermal stability and electrochemical properties of the cathode material are studied in detail. The Pr 2 Ni 1- x Nb x O 4 exhibits a K 2 NiF 4 type structure with Fmmm space group. The Nb5+ cations that doped into Pr 2 NiO 4 replaces the Ni site, which increases the surface oxygen content, then effectively eliminates the phase transition of Pr 2 NiO 4 and significantly improves the ORR catalytic activity. The Pr 2 Ni 0.9 Nb 0.1 O 4 was found to occupy the lowest polarization resistance of 0.057 Ω cm2, and the peak power density of single cells supported by the electrolyte is 0.576 W cm−2 at 700 °C, which has good long-term stability. [Display omitted] • The structure and performance of the cobalt-free Pr 2 Ni 1- x Nb x O 4 cathodes are studied. • Nb-doping can eliminate the phase change and improve the stability of the structures. • Nb-doping can increase the ORR activity of the Pr 2 Ni 1- x Nb x O 4 cathode. • Pr 2 Ni 0.9 Nb 0.1 O 4 cathode exhibits a low polarization resistance of 0.057 Ω cm2. • The highest peak power density is 0.576 W cm−2 at 700 °C with Pr 2 Ni 0.9 Nb 0.1 O 4 cathode. [ABSTRACT FROM AUTHOR]