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.

Automated summary

F-doped layered double perovskites exhibit bifunctional activity in both solid oxide fuel cell and solid oxide electrolysis cell models, attributed to increased oxygen vacancy concentration and enhanced electrical conductivity induced by F doping. The F- anions are successfully introduced into the host lattice, promoting the oxygen surface exchange/diffusion rates. The covalence between Co 3d and O 2p-orbital is enlarged in the F-doped model, leading to improved oxygen reduction and oxygen evolution reaction activities.