A top-down strategy for the synthesis of mesoporous Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ as a cathode precursor for buffer layer-free deposition on stabilized zirconia electrolyte with a superior electrochemical performance

We develop a facile and effective top-down method for the fabrication of mesoporous Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) oxide with a high specific surface area (∼25 m² g^-1). The original BSCF is first synthesized by the simple EDTA-citric acid complexing method, and then treated in H₂O₂ to obtain the mesoporous BSCF. The structure and morphology of as-prepared BSCF power is systematically characterized by N₂ adsorption/desorption isotherms, XRD, TEM, SEM and ICP techniques. A possible mechanism for the creation of mesoporous BSCF is proposed, in which Ba²⁺ and Sr²⁺ dissolve selectively from partial BSCF particles during the catalytic decomposition of H₂O₂. The electrochemical properties are investigated by the EIS and I-V test in the symmetrical cell and integrated single cell configurations, respectively. The interfacial reaction between BSCF electrode and YSZ electrolyte was suppressed successfully by using the BSCF with high specific surface area to decrease the sintering temperature (800 °C), thus the electrode exhibits high oxygen reduction reaction activity. The solid oxide fuel cell (SOFC) achieves an exciting peak power density of ∼1800 mW cm^-2 at 800 °C, signifying the mesoporous BSCF, together with the preparation method, has a good application prospect in the development of SOFCs.