Exceptionally stable double perovskite Sr2-xFeTaO6- as fuel electrode for solid oxide cells

Developing fuel electrodes with excellent structural stability and high catalytic activity under various fuel conditions is highly desirable for large-scale applications of solid oxide cells (SOCs). In this study, double perovskite Sr2-xFeTaO6-delta (x = 0, 0.1, 0.2, 0.3) materials were designed as fuel electrodes for SOCs. Sr1.8FeTaO6-delta (S18FT) was synthesized in air, and its structural stability could be maintained in both 5 % H2/Ar and pure CO2 after calcination at 850 degrees C for 10 h. The thermal expansion coefficient of S18FT was 11.8 x 10-6 K-1 at 50-850 degrees C. To further improve the electrochemical performance of the S18FT electrode, it was impregnated with Pd (NO3)2 to form a composite electrode (Pd-SFT-SDC). When hydrogen, propane, ethyl ethanol, and biochar were used as fuels, the maximum power densities of the fuel cells at 850 degrees C were 1114, 370, 474, and 291 mW cm-2, respectively. The fuel cell operated stably for 300 h when using propane. When the solid oxide electrolysis cell mode was used for the co-electrolysis of CO2/H2O, the current density was -0.835 A cm-2 at 1.3 V and 800 degrees C. These results indicated the potential for the use of the Pd-SFT-SDC composite material as a fuel electrode for SOCs.