Regulating oxygen vacancy through Sr defect to enhance Pr0.6Sr0.4-xCo0.2Fe0.8O3-δ cathode activity for SOFCs

The formation of oxygen vacancies in cathode materials for solid oxide fuel cells (SOFCs) plays a pivotal role in enhancing the oxygen reduction reaction (ORR) activity. Perovskite-type oxides are regarded as promising cathode candidates owing to their inherent mixed ionic and electronic conductivity (MIEC). In this study, we engineered a series of Pr 0.6 Sr 0.4-x Co 0.2 Fe 0.8 O 3-δ (where x= 0, 0.05, 0.1, 0.15, denoted as PSCF40, PSCF35, PSCF30 and PSCF25, respectively) cathode through Sr defect and systematically investigated the effects of this modification on oxygen vacancy content and ORR catalytic activity. The A-site Sr deficiency directly regulates the oxygen vacancy concentration and oxygen ion migration capability in perovskite through charge compensation effects. When the defect concentration reached 0.1, the PSCF30 demonstrated optimal electrochemical performance. At 750 °C, the polarization impedance of PSCF30 is only 0.060 Ω cm 2 . Meanwhile, the peak power density of SFM-GDC/LSGM/GDC/PSCF30 single cell is 404.38 mW cm −2 , which is 39.7% higher than that of PSCF40 (289.38 mW cm −2 ). This study emphasizes the important role of appropriately increasing the oxygen vacancy concentration, suggesting that the introduction of appropriate A-site defect in the material is a feasible approach to improve the ORR catalytic activity and ionic conductivity of the cathode.