Engineering the one-pot synthesized Ba(Ce,Fe)O₃-based composites as triple-conducting electrodes for solid oxide electrochemical cell applications

Designing highly active electrode materials is one of the most crucial issues in the development of low- and intermediate-temperature solid oxide electrochemical cells. Although a variety of electrode candidates and their chemical modifications have been proposed, the ideal material has not yet been identified. It is widely recognized that the triple-conducting behavior of electrodes is advantageous for solid oxide electrochemical cells, particularly those based on proton-conducting electrolytes. This is due to the ability to conduct three different charge carriers (holes, oxygen ions, protons) simultaneously, providing improved electrode kinetics as a result of rapid extension of the active surface area toward oxygen reduction and oxygen evolution reactions. This review underscores the current status and recent advancements in the utilization of dual-phase triple-conducting compounds belonging to the barium cerate-ferrite family, Ba(Ce,Fe)O₃. In detail, the phase relationships, proton transport, electrical conductivity, thermal expansion behavior, and electrochemical performance of such materials are thoroughly discussed, revealing the main regularities from the literature as well as formulating prospects and limitations from the applied viewpoints. Therefore, this work provides fundamental information on basic and acceptor-doped Ba(Ce,Fe)O₃-based composites, which can further be used for rational design and engineering of one-pot synthesized dual-phase materials for electrochemical purposes.