A-site deficient Sr0.9Ti0.3Fe0.7O3−δ perovskite：A high stable cobalt-free oxygen electrode material for solid oxide electrochemical cells with excellent electrocatalytic activity and CO2 tolerance

Recently, SrTi 0.3 Fe 0.7 O 3−δ (STF) has been investigated as a highly stable oxygen electrode material for solid oxide electrochemical cells (SOCs) with a sufficiently low resistance for cell operation at temperatures of > 700 °C. However, in general, the STF electrode performance is limited at temperatures of ≤ 700 °C due to the low oxygen surface exchange coefficient, which is mainly caused by high Sr surface segregation. To improve the electrode performance, Sr 0.9 (Ti 0.3 Fe 0.7 )O 3−δ (A-STF) with an A-site-deficient design is developed to reduce the Sr content and thus reduce the Sr surface segregation, thereby providing a unique combination of excellent oxygen electrode performance and long-term stability. The A-site deficiency reduces the electrode polarization resistance by > 3 times at 600 °C and clearly improves the oxygen diffusion and surface exchange coefficients due to the decrease of Sr surface segregation. The A-STF electrode exhibits stable performance in the fuel cell and electrolysis modes at 1 A cm −2 > 1200 h. The stability of STF-based oxygen electrodes in a CO 2 -enriched atmosphere is investigated, and the results indicate that A-STF exhibits excellent CO 2 tolerance.