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Improving the Electrocatalytic Activity and Durability of the La0.6Sr0.4Co0.2Fe0.8O3−δ Cathode by Surface Modification
journal contribution
posted on 2018-10-29, 00:00 authored by Huijun Chen, Zheng Guo, Lei A. Zhang, Yifeng Li, Fei Li, Yapeng Zhang, Yu Chen, Xinwei Wang, Bo Yu, Jian-min Shi, Jiang Liu, Chenghao Yang, Shuang Cheng, Yan Chen, Meilin LiuElectrode materials
with high activity and good stability are essential for commercialization
of energy conversion systems such as solid oxide fuel cells or electrolysis
cells at the intermediate temperature. Modifying the existing perovskite-based
electrode surface to form a heterostructure has been widely applied
for the rational design of novel electrodes with high performance.
Despite many successful developments in enhancing electrode performance
by surface modification, some controversial results are also reported
in the literature and the mechanisms are still not well understood.
In this work, the mechanism of how surface modification impacts the
oxygen reduction reaction (ORR) activity and stability of perovskite-based
oxides was investigated. We took La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) as the thin-film model
system and modified its surface with additive PrxCe1–xO2 layers
of different thicknesses. We found a strong correlation between surface
oxygen defects and the ORR activity of the heterostructure. By inducing
higher oxygen vacancy concentration compared to bare LSCF, PrO2 coating is proved to greatly facilitate the rate of oxygen
dissociation, thus significantly enhancing the ORR activity. Because
of low oxygen vacancy density introduced by Pr0.2Ce0.8O2 and CeO2 coating, on the one hand,
it does not boost the rate of ORR but successfully suppresses surface
Sr segregation, leading to an enhanced durability. Our findings demonstrate
the vital role of surface oxygen defects and provide important insights
for the rational design of high-performance electrode materials through
surface defect engineering.
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surface modification impactsCeO 2 coatingsurface defect engineeringsurface Sr segregationoxygen vacancy densityoxygen reduction reactionthin-film model systemoxide fuel cellsPrO 2 coatingLSCFenergy conversion systemsperovskite-based electrode surfaceLa 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3ORR activityPr 0.2 Ce 0.8 O 2surface oxygen defectsSurface Modification Electrode materialsoxygen vacancy concentration
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