Highly Efficient and Stable Intermediate-Temperature Solid Oxide Fuel Cells Using PrCo_0.5Ni_0.5O_3−δ Cathode

Oxygen reduction reaction is crucial for the development of intermediate/low-temperature solid oxide fuel cells (SOFCs), thus the development of cathode materials with high catalytic activity and stability is still a great challenge for the commercialization of SOFC. In this study, a series of La 1– x Pr x Co 0.5 Ni 0.5 O 3−δ ( x = 0.5, 0.75, and 1.0) perovskite oxides were prepared as oxygen reduction reaction catalysts for SOFC. First, the polycrystalline powders were synthesized by a Pechini method, and the crystal structure was confirmed as orthorhombic symmetry with Pbnm (No. 62) space group. Second, it was found that PrCo 0.5 Ni 0.5 O 3−δ (PCN) presents the best electrochemical performance among the three compounds. The polarization impedance of PCN was 0.0383 Ω cm 2 and the peak power density reached 1.47 W cm 2 using wetted hydrogen as fuel and air as the oxidant measured at 850 °C. Meanwhile, the single cell with PCN as the cathode could stably work for 100 h at 750 °C without damping. Finally, combined with the first-principles calculations, it was revealed that the doping of Pr ion can effectively reduce oxygen vacancy formation energy and mainly changed the valence states of Co and Ni ions at B-site. Therefore, PCN is expected to be a promising cathode material for SOFC.