Advanced electrochemical activity and CO2 tolerance of iron-based cathode electrocatalyst for solid oxide fuel cells

Here, we report the Sr0.5Bi0.4Ca0.1FeO3−δ (SBCF) and Sr0.5Bi0.5FeO3−δ (SBF) oxides, which are regarded as the oxygen electrodes for solid oxide fuel cells (SOFCs). The Ca2+ cations that doped into SBF substitutes the Bi3+ site, which can increase the oxygen vacancy concentration, promote the oxygen transport kinetics, enhance the electrical conductivity, and improve the electrochemical activity. Impedance result shows that SBCF possesses a lower polarization resistance of 0.13 Ω cm2 at 700 °C. Additionally, SBCF performs well in single cells, achieving a peak power density of 0.83 W cm−2 at 650 °C and a superior durability for ∼ 100 h. When SBCF electrode is exposed to a CO2-containing atmosphere, no carbonate species are formed on SBCF cathode, indicating that SBCF has a good CO2 tolerance. The high activity and good chemical stability make SBCF a potential electrode for SOFCs.