Oxygen-ionic transport of (Pr,Ba)FeO3-based perovskite materials: Results from oxygen permeability experiments

Fe-containing perovskite materials have attracted considerable attention in the field of high temperature electrochemistry as potential electrode materials for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). Belonging to the cobalt-free family of materials, they exhibit high redox stability, acceptable thermal expansion behavior, and good electronic conductivity. However, in order to design electrochemically active electrodes towards oxygen reduction and evolution reactions, the oxygen-ionic conductivity of the iron-based materials must also be high. In the present work, the oxygen-ion transport behavior of Pr_0.6Ba₀₄FeO_3–δ (PBF) was comprehensively investigated by oxygen permeation experiments as a function of doping effects (Pr_0.6Ba_0·.4Fe_0.9M_0.1O_3–δ, M = Ni, Cu, and Co) and external parameters. In detail, three-layer porous|dense|porous membranes with a dense layer thickness of ∼100 μm were successfully prepared by the tape calendaring method followed by their electrochemical characterization. It was found that the highest oxygen permeation fluxes were obtained for the basic PBF composition, while the Co-containing membrane showed the inferior permeation properties. The Ni- and Cu-doped PBF materials were intermediate in permeation properties and derived oxygen-ionic conductivity. These data, together with other functional properties tailored by doping, make Ni- and Cu-containing materials one of the most promising derivatives from (Pr,Ba)FeO_3–δ for electrochemical applications.