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 (Pr1.1Ba0.9Co2O5 +/- dFx) 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 cal-culations, 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 Pr1.1Ba0.9Co2O5 +/- dF0.1 (P1.1BCOF0.1) electrode is as low as 0.033 U/cm2 at 700 degrees C. The P1.1BCOF0.1 cathode-based fuel cell delivers a peak power density of 1102 mW/cm2, along with an excellent operating stability at 700 degrees C. Moreover, the current density of 1335 mA/cm2 is achieved in the P1.1BCOF0.1 anode-based electrolysis cell at 1.8 V toward CO2 reduction reaction at 750 degrees 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.(c) 2023 Elsevier Ltd. All rights reserved.