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.
Highlights
Perovskite-type materials are the promising cathodes for solid oxide fuel cells (SOFCs) [1,2,3].Among the perovskite oxides, the Co-containing perovskite materials with mixed ionic-electronic conducting feature have been widely investigated due to their remarkable electrochemical performance for oxygen reduction reaction (ORR) [4,5,6]
Co-containing oxides show some other drawbacks, such as poor chemical stability, higher thermal expansion coefficient, and strong volatility, which inhibit their wide applications in SOFCs [7,8]
The results provide an effective strategy for designing novel cathode electrocatalysts for SOFCs
Summary
Perovskite-type materials are the promising cathodes for solid oxide fuel cells (SOFCs) [1,2,3]. Co-containing oxides show some other drawbacks, such as poor chemical stability, higher thermal expansion coefficient, and strong volatility, which inhibit their wide applications in SOFCs [7,8] To address these issues, developing new cathodes with improved electrochemical performance and good chemical stability is an important trend. Among the Fe-based oxides, BaFeO3−δ presents attractive oxygen permeation flux and fast oxygen surface exchange kinetics [13,14] This is mainly due to variable valence and excellent chemical stability of Fe ions, as well as lower valence and larger ionic radius of Ba2+ , which facilitates the electrochemical performance and oxygen transport of the materials [15]. The results provide an effective strategy for designing novel cathode electrocatalysts for SOFCs
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