Layered oxygen-deficient double perovskite GdBaFe2O5+δ as electrode material for symmetrical solid-oxide fuel cells

Abstract A highly efficient and stable catalyst is critically required for simultaneous oxygen reduction and fuel oxidation in symmetrical solid-oxide fuel cells (SSOFCs). Herein, a novel material named as layered oxygen-deficient double perovskite GdBaFe2O5+δ (GBFO; δ = 0.25 and 0.5) for SSOFC electrodes was synthesized in oxidizing and reducing atmospheres and exhibited excellent structural stability under cathode and anode conditions. La0.9Sr0.1Ga0.8Mg0.2O3–δ (LSGM) and Ce0.8Sm0.2O1.9 (SDC) were used as electrolyte and buffer layer, respectively. The polarization resistance values of the GBFO electrodes on LSGM electrolytes were as low as 0.054 and 0.974 Ω cm2 at 850°C in air and H2, respectively. The maximum power densities obtained from a cell with the configuration of GBFO/SDC/LSGM (200 μm)/SDC/GBFO were 1053, 868, and 197 mW cm−2 at 850°C with H2, wet syngas, and wet CH4 as fuel, respectively. The formation mechanism of oxygen vacancies and the structural stability of GBFO were also analyzed and discussed. GBFO showed good electrochemical stability and resistance to carbon deposition based on a 120-hour test with wet CH4 as fuel. These findings indicate the potential use of this material in SSOFCs running on hydrocarbon fuels.