Insights in to the electrochemical activity of fe-based perovskite cathodes toward oxygen reduction reaction for solid oxide fuel cells

Abstract

The development of novel oxygen reduction electrodes with superior electrocatalytic activity and CO2 durability is a major challenge for solid oxide fuel cells (SOFCs). Here, novel cobalt-free perovskite oxides, BaFe1−xYxO3−δ (x = 0.05, 0.10, and 0.15) denoted as BFY05, BFY10, and BFY15, are intensively evaluated as oxygen reduction electrode candidate for solid oxide fuel cells. These materials have been synthesized and the electrocatalytic activity for oxygen reduction reaction (ORR) has been investigated systematically. The BFY10 cathode exhibits the best electrocatalytic performance with a lowest polarization resistance of 0.057 Ω cm2 at 700◦C. Meanwhile, the single cells with the BFY05, BFY10 and BFY15 cathodes deliver the peak power densities of 0.73, 1.1, and 0.89 W cm−2 at 700◦C, respectively. Furthermore, electrochemical impedance spectra (EIS) are analyzed by means of distribution of relaxation time (DRT). The results indicate that the oxygen adsorption-dissociation process is determined to be the rate-limiting step at the electrode interface. In addition, the single cell with the BFY10 cathode exhibits a good long-term stability at 700◦C under an output voltage of 0.5 V for 120 h.