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The effect of molten carbonates (MCs) on polarization resistance (RP), a direct measure of oxygen reduction reaction (ORR) activity, of a composite La0.8Sr0.2MnO3+δ/Ce0.8Gd0.2O2-δ (LSM/GDC) solid oxide fuel cell (SOFC) cathode has been systematically investigated in this study over a temperature range of 550–650°C and partial pressure of oxygen (pO2) span of 10−3 ∼ 1 atm. It is shown that the LSM/GDC cathode, either in the pristine or MC-modified states, can be generally modeled by two consecutive parallel circuits consisting of a resistance and a constant phase element (CPE). The high-frequency RP(HF)//CPE(HF) component is related to a charge-transfer process, while the low-frequency RP(LF)//CPE(LF) counterpart is associated with a surface oxygen dissociative adsorption process. Incorporation of an adequate amount of MC significantly reduces RP(LF) by as much as a factor of 10. Studies on the dependence of RP on temperature and pO2 further reveal that the rate-limiting step of a LSM/GDC cathode has shifted from the original surface oxygen dissociative adsorption to the formation of an intermediate CO2 −4 species in the presence of MC.


©Journal of The Electrochemical Society 2013, The Electrochemcial Society.

© The Electrochemical Society, Inc. 2013. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of The Electrochemical Society.

Publisher’s Version:

Gong, Y., Li, X., Zhang, L., Tharp, W., Qin, C., & Huang, K. (December 20, 2013). Promoting Electrocatalytic Activity of a Composite SOFC Cathode La0.8Sr0.2MnO3+δ/Ce0.8Gd0.2O2-δ with Molten Carbonates. Journal of The Electrochemical Society, 161 (3), F226 – F232.