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 Nb 5+ 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 cm 2 , 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.