The oxygen reduction mechanism at porous Sm0.5Sr0.5CoO3−δ/Sm0.2Ce0.8O1.9 composite cathode, in which Sm0.5Sr0.5CoO3−δ is a perovskite type mixed ionic and electronic conductor (MIEC), was studied with respect to the oxygen partial pressure and temperature. Symmetric half cells with Sm0.2Ce0.8O1.9 electrolyte were prepared, and cathode behavior was measured by using electrochemical impedance spectroscopy at frequency range of 0.1Hz∼5MHz and temperature range of 400∼900°C. Oxygen partial pressure range for the measurement was from 0.0002 to 1atm. In present research, reaction model based on the empirical equivalent circuit was established. Three elementary reaction steps were considered to describe the oxygen reduction reaction at Sm0.5Sr0.5CoO3−δ/Sm0.2Ce0.8O1.9 composite cathode. Electrode resistances corresponding to the high and low frequency seem to represent the oxygen ion transfer at the interface of electrolyte and gas phase diffusion of oxygen, respectively, from electrochemical impedance analyses as functions of oxygen partial pressure and temperature. The medium frequency process is expected to correspond to the oxygen ion conduction in the bulk cathode from this study.
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Oxygen Reduction Mechanism at Sm0.5Sr0.5CoO3−δ/Sm0.2Ce0.8O1.9 Composite Cathode for Solid Oxide Fuel Cell
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Baek, S, Bae, J, & Kim, JH. "Oxygen Reduction Mechanism at Sm0.5Sr0.5CoO3−δ/Sm0.2Ce0.8O1.9 Composite Cathode for Solid Oxide Fuel Cell." Proceedings of the ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. Denver, Colorado, USA. June 16–18, 2008. pp. 935-938. ASME. https://doi.org/10.1115/FuelCell2008-65059
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