Unveiling positive impacts of fluorine anion doping on extraordinary catalytic activity of bifunctional-layered double perovskite electrodes for solid oxide fuel cells and electrolysis cells

To address the impacts of anion doping, F-doped layered double perovskites (Pr 1.1 Ba 0.9 Co 2 O 5+ δ F x ) have been synthesized, demonstrating bifunctional activity in both solid oxide fuel cell and solid oxide electrolysis cell models. The F doping induces increased oxygen vacancy concentration and enhanced electrical conductivity . Combined with spherical aberration-corrected transmission electron microscopy and X-ray photoelectron spectroscopy analyses, the F − anions are successfully introduced into the host lattice, promoting the oxygen surface exchange/diffusion rates. From the density functional theory calculations, the covalence between Co 3d and O 2p-orbital is enlarged in the F-doped model, and both oxygen reduction reaction and oxygen evolution reaction activities are improved. The area-specific resistance of the Pr 1.1 Ba 0.9 Co 2 O 5+ δ F 0.1 (P 1.1 BCOF 0.1 ) electrode is as low as 0.033 Ω/cm 2 at 700 °C. The P 1.1 BCOF 0.1 cathode-based fuel cell delivers a peak power density of 1102 mW/cm 2 , along with an excellent operating stability at 700 °C. Moreover, the current density of 1335 mA/cm 2 is achieved in the P 1.1 BCOF 0.1 anode-based electrolysis cell at 1.8 V toward CO 2 reduction reaction at 750 °C. These results here highlight the performance origin and bifunctional activity of fluorine-doped perovskite materials, which may help us rationally design the oxide catalysts.