Tailoring the electronic structure of the perovskite oxide could potentially allow dramatic improvements in the properties of cathode materials in proton-conducting solid oxide fuel cells (SOFCs). This has been demonstrated in the case of Mo-doped La0.5Sr0.5FeO3-δ, where the electronic structure of the La0.5Sr0.5FeO3-δ oxide has been changed with the Mo-doping, leading to a less strong metal-oxygen bond as well as a more active surface towards oxygen reduction. As a result, the more active oxygen atoms make the formation of oxygen vacancy and hydration that are critical for protonation more feasible. Furthermore, the electric field induced by Mo-doping provides an additional driving force for the movement of protons, accelerating the proton migrations in the oxide and thus improving the cathode performance. With the Mo-doped La0.5Sr0.5FeO3-δ as the cathode, a proton-conducting SOFC exhibits an impressive fuel cell output of 1174 mW cm−2 at 700 °C that surpasses most of the cells using similar types of cathodes. This study not only provides a proper cathode material without involving cobalt and barium elements but also gives an understanding of the design of the cathode by tailoring the electronic structures.
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