Enhanced electrode reaction for La_0.8Sr_0.2FeO_3-δ-Sm_0.2Ce_0.8O_1.9 composite cathode by barium carbonate nanoparticles as a synergistic catalyst

BaCO₃ nanoparticles are demonstrated as outstanding catalysts for high-temperature oxygen reduction reaction on the La_0.8Sr_0.2FeO_3-δ (LSF)-Sm_0.2Ce_0.8O_2−δ (SDC) cathode for solid oxide fuel cells (SOFCs). X-ray diffraction shows that BaCO₃ is chemically compatible with LSF and SDC under the fabrication and operation conditions of intermediate-temperature SOFCs. The BaCO₃ nanoparticles can greatly reduce the interfacial polarization resistance; from 1.65 to 0.35 Ω cm² at 700 °C when 7.6wt% BaCO₃ is infiltrated to the porous LSF-SDC electrode. Electrochemical impedance spectra also show that there are both significantly decrease in high- and low-frequency resistance, indicating that BaCO₃ nanoparticles can greatly enhance the oxygen ions transfer and surface reaction steps in LSF-SDC composite cathode. In addition, LSF-SDC cathodes with infiltrated BaCO₃ nanoparticles have shown excellent stability and substantially enhanced single-cell performance, suggesting BaCO₃ nanoparticles are very effective as a catalytic phase for LSF-SDC cathode.