Chemical stability aspects of BaCe0.7–xFexZr0.2Y0.1O3–δ mixed ionic-electronic conductors as promising electrodes for protonic ceramic fuel cells

Mixed ion-electron conductors (MIECs) are promising materials for air electrodes for protonic ceramic fuel cells (PCFCs) or oxygen permeation membranes. In this work, various aspects of the chemical stability of Co-free MIEC materials, BaCe0.7–xFexZr0.2Y0.1O3–δ, were studied, including their interaction with another functional material (BaCe0.5Zr0.3Y0.1Yb0.1O3–δ-based proton-conducting electrolyte) and gas components (H2O, CO2, and H2). Chemical compatibility studies indicate no visible chemical interaction between the electrode and electrolyte materials even at 1200 °C, which is significantly higher than the operating temperatures (600–800 °C) of PCFCs. The treatments of BaCe0.7–xFexZr0.2Y0.1O3–δ in different atmospheres at 1100 °C, according to the XRD, SEM, IR and Raman spectroscopy data, resulted in the formation of impurity phases. However, their extremely small amounts suggest that they may not form at the operating temperatures. Thus, it can be assumed that the studied materials can be good candidates for various electrochemical applications.