An improved oxygen reduction reaction activity and CO2-tolerance of La0.6Sr0.4Co0.2Fe0.8O3- δ achieved by a surface modification with barium cobaltite coatings

作者：Pei, Kai; Zhou, Yucun; Ding, Yong; Xu, Kang; Zhang, Hua; Yuan, Wei; Sasaki, Kotaro; Choi, YongMan^*; Liu, Meilin^*; Chen, Yu^*

来源：Journal of Power Sources, 2021, 514: 230573.

DOI：10.1016/j.jpowsour.2021.230573

• Oxygen reduction reaction
• Fuel cells
• Surface modification
• Catalyst coating

Solid oxide fuel cells (SOFCs) cathode often suffers from the poisoning effect of the contaminants commonly encountered in air such as CO2. Here we report an effective approach to enhancing the activity and CO2 tolerance of the state-of-the-art La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) cathode enabled by a coating of BaCoO3-8 (BCO), as verified by the electrochemical testings, Raman analyses, and density functional theory calculations. When surface modified with a thin-film BCO coating, LSCF displays a much enhanced ORR activity and an improved durability against CO2. For example, anode supported SOFCs with the LSCF cathode coated with BCO coatings show a remarkable peak power density (P-max) of 0.41 Wcm(-2) and a significantly reduced degradation rate in current density of similar to 0.08%h(-1) at 0.8 V and 700 degrees C for a period of 300 hs when humidified H-2 (with 3 vol%H2O) was used as fuel and air with 8 vol% CO2 as oxidant. The demonstrated performance is improved when compared with those of the cells with a blank LSCF electrode (a P-max of similar to 0.36 Wcm(-2) and a degradation rate of similar to 0.15%h(-1)) under the same conditions. The adsorption energy calculations suggests that BCO coating makes CO2 adsorption much weaker than LSCF (-0.54 eV versus-1.07 eV).

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