Modification of B-site substituted by high-valence Nb in PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _{5+ <i>δ</i>} as a highly active air electrode for solid oxide fuel cell

Solid oxide fuel cells (SOFCs) are a new type of power generation technology that directly converts chemical energy into electrical energy with advantages, such as low environmental pollution and high conversion efficiency. However, these fuel cells suffer challenges, including high operating temperatures and poor stability. In this paper, PrBa_0.5Sr_0.5Co_1.5-<i>x</i> Nb _<i>x</i> Fe_0.5O_5+<i>δ</i> series materials were prepared <i>via</i> the sol-gel method and applied as cathode material in SOFCs. X-ray diffraction patterns reveal that the addition of Nb to PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+<i>δ</i> did not change its crystal structure but increased the cell volume, leading to lattice expansion and improved thermal stability. Electron paramagnetic resonance quantitative analysis was conducted on PrBa_0.5Sr_0.5Co_1.5-<i>x</i> Nb _<i>x</i> Fe_0.5O_5+<i>δ</i> . At 800 °C, the lowest area specific resistance (ASR) at <i>x</i> = 0.04 was 0.0336 Ω cm², indicating that the addition of Nb significantly improved the oxygen reduction reaction catalytic activity. The power density of the electrolyte-supported single cell increased by 110.6 mW cm^-2. Thus, Nb addition enhances the electrochemical performance of PBSCF cathode materials, and PBSCFNb_0.04 is a promising cathode material for SOFCs.