An efficient and robust Co-free BaFeO3-based oxygen electrode for protonic ceramic electrochemical cells

Protonic ceramic electrochemical cells (PCECs) are promising devices for sustainable energy conversion and storage with high efficiency and low cost. However, the application of PCECs is limited by the scarcity of oxygen electrode materials with excellent oxygen reduction/evolution reaction (ORR/OER) activity and robust durability. In this investigation, perovskite oxide with specific non-stoichiometric ratios, namely Ba0.9Sr0.05La0.05Fe0.8Zn0.1Y0.1O3 (BSLFZY) are synthesized using a sol-gel method, and electrochemically evaluated as oxygen electrodes for PCECs. The structural and chemical stability of the synthesized material is explored and analyzed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Surface catalytic activity is assessed using X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), and oxygen temperature-programmed desorption techniques (O2-TPD). Additionally, the electronic conductivity results demonstrate the suitability of BSLFZY for application in PCECs. The electrochemical performance of the material is estimated using a homemade Ni-BZCYYb/BZCYYb cell with a BSLFZY oxygen electrode. Electrochemical impedance spectra within a specific temperature range are analyzed using the distribution of relaxation times (DRT) method. The results offer valuable insights into the underlying reasons for long-term electrochemical performance degradation in fuel cell (FC) mode. These results present the potential of BSLFZY for practical applications in PCECs, highlighting its excellent electrochemical performance and durability.