Insights into the oxygen reduction reaction on Cu-doped SrFeO3- cathode for solid oxide fuel cells

In this study, perovskite oxides SrFe1-xCuxO3-δ are systematically evaluated as potential cathodes for intermediate temperature solid oxide fuel cells. Cu doping is found to decrease the unit cell volume, while the average valence of iron and the oxygen vacancy content increase steadily in SrFe1-xCuxO3-δ. The conductivity relaxation test proves that the higher the doping amount of Cu, the larger the Dchem and kchem values of the material. Among the copper doped materials, SrFe0.7Cu0.3O3-δ shows the best catalytic performance for oxygen reduction reaction. The polarization resistance is 0.107 Ω cm2, and the peak power density reaches 858 mW cm−2 at 700 °C. Furthermore, the charge transfer process is identified to be the rate control step of the oxygen reduction reaction on this cathode. Finally, the first-principles computation result confirms that introducing Cu reduces the formation energy of oxygen vacancies, which yields favorable conditions for producing oxygen vacancy in Cu-doped SrFeO3.