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Title: Improving the Electrocatalytic Activity and Durability of the La 0.6Sr 0.4Co 0.2Fe 0.8O 3-δ Cathode by Surface Modification

Abstract

Electrode 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 La 0.6Sr 0.4Co 0.2Fe 0.8O 3 (LSCF) as the thin-film model system and modified its surface with additive Pr xCe 1–xO 2 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, PrO 2 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 Pr 0.2Ce 0.8O 2 and CeO 2 coating, on the one hand, it does notmore » boost the rate of ORR but successfully suppresses surface Sr segregation, leading to an enhanced durability. Our findings will 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.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [1];  [1];  [3]; ORCiD logo [2];  [4];  [5]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [6]; ORCiD logo [3]
  1. South China Univ. of Technology (SCUT), Guangzhou (China); South China Univ. of Technology (SCUT), Guangzhou (China). School of Environment and Energy, Guangzhou Key Lab. for Surface Chemistry of Energy Materials, New Energy Inst.
  2. Peking Univ., Beijing (China). School of Advanced Materials
  3. Georgia Inst. of Technology, Atlanta, GA (United States). Materials Science and Engineering
  4. Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology (INET)
  5. China Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry
  6. South China Univ. of Technology (SCUT), Guangzhou (China); South China Univ. of Technology (SCUT), Guangzhou (China). School of Environment and Energy, Guangzhou Key Lab. for Surface Chemistry of Energy Materials, New Energy Inst.; Guangdong Engineering and Technology Research Center for Surface Chemistry of Energy Materials, School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1543694
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 10; Journal Issue: 46; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
Science & Technology - Other Topics; Materials Science

Citation Formats

Chen, Huijun, Guo, Zheng, Zhang, Lei A., Li, Yifeng, Li, Fei, Zhang, Yapeng, Chen, Yu, Wang, Xinwei, Yu, Bo, Shi, Jian-min, Liu, Jiang, Yang, Chenghao, Cheng, Shuang, Chen, Yan, and Liu, Meilin. Improving the Electrocatalytic Activity and Durability of the La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode by Surface Modification. United States: N. p., 2018. Web. doi:10.1021/acsami.8b14693.
Chen, Huijun, Guo, Zheng, Zhang, Lei A., Li, Yifeng, Li, Fei, Zhang, Yapeng, Chen, Yu, Wang, Xinwei, Yu, Bo, Shi, Jian-min, Liu, Jiang, Yang, Chenghao, Cheng, Shuang, Chen, Yan, & Liu, Meilin. Improving the Electrocatalytic Activity and Durability of the La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode by Surface Modification. United States. doi:10.1021/acsami.8b14693.
Chen, Huijun, Guo, Zheng, Zhang, Lei A., Li, Yifeng, Li, Fei, Zhang, Yapeng, Chen, Yu, Wang, Xinwei, Yu, Bo, Shi, Jian-min, Liu, Jiang, Yang, Chenghao, Cheng, Shuang, Chen, Yan, and Liu, Meilin. Thu . "Improving the Electrocatalytic Activity and Durability of the La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode by Surface Modification". United States. doi:10.1021/acsami.8b14693. https://www.osti.gov/servlets/purl/1543694.
@article{osti_1543694,
title = {Improving the Electrocatalytic Activity and Durability of the La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode by Surface Modification},
author = {Chen, Huijun and Guo, Zheng and Zhang, Lei A. and Li, Yifeng and Li, Fei and Zhang, Yapeng and Chen, Yu and Wang, Xinwei and Yu, Bo and Shi, Jian-min and Liu, Jiang and Yang, Chenghao and Cheng, Shuang and Chen, Yan and Liu, Meilin},
abstractNote = {Electrode 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 will 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.},
doi = {10.1021/acsami.8b14693},
journal = {ACS Applied Materials and Interfaces},
number = 46,
volume = 10,
place = {United States},
year = {2018},
month = {10}
}

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