Improved electrocatalytic activity and CO2 tolerance of iron-based perovskite as an intermediate temperature SOFC cathode

The present study focuses on the improving of electrocatalytic performance in Fe-based perovskites through Pr ion doping at the A-site of La0.5Sr0.5FeO3-δ (LSF) perovskites. Iodine titration experiments and thermogravimetric results revealed that La0.5Sr0.4Pr0.1FeO3-δ (LSPF1) doped with Pr exhibited a high concentration of oxygen vacancies. Additionally, electrical conductivity relaxation tests confirmed that LSPF1 enhanced surface oxygen exchange and bulk diffusion capabilities, thereby benefiting the electrocatalytic activity of the cathode. The results indicate that Pr-doped La0.5Sr0.4Pr0.1FeO3-δ (LSPF1) has a high oxygen vacancy content, which enhances the surface oxygen exchange and body diffusion capacity of the cathode and enhances the overall electrocatalytic activity of the cathode. At 750 °C, the LSPF1 cathode exhibited a polarization resistance of 0.090 Ω cm2, which is lower than 0.131 Ω cm2 of LSF. As a single cell cathode, LSPF1 achieved a peak power density of 0.583 W cm−2 at 700 °C, surpassing that of an LSF-based single-cell by 1.44 times and demonstrating excellent stability during a 100 h testing period. In addition, replacing Sr with Pr reduces the alkaline earth metal content on the cathode surface, increases the acidity of the cathode, and hinders its reaction with CO2 to form a carbonate barrier layer. Therefore, in CO2 tolerance testing, LSPF1 exhibits better stability than LSF. Overall, LSPF1 is expected to become an intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode material with outstanding CO2 tolerance and electrocatalytic activity.