title: Mechanism for the enhanced oxygen reduction reaction of La0.6Sr0.4Co0.2Fe0.8O3-δby strontium carbonate.
abstract: Strontium doped lanthanum cobalt ferrite (LSCF) is a widely applied electrocatalyst for the oxygen reduction reaction (ORR) in solid-oxide fuel cells (SOFCs) operated at intermediate temperatures. Sr surface segregation in long-term operation has been reported to have contradicting effects that either degrade or improve the reaction. Thus, it is critical to understand the mechanism of surface Sr compounds on ORR kinetics. This work aims to verify the effect and propose the mechanism by decorating SrCO3nanoparticles using the infiltration method. Electrochemical conductivity relaxation measurements show that SrCO3particles improve the chemical oxygen surface exchange coefficient by up to a factor of 100. The electrochemical performance is significantly improved by the infiltration of SrCO3, which is comparable to those obtained by typical electrocatalysts including precious metals such as Pd and Rh. Distribution of relaxation time (DRT) analysis shows that the performance enhancement is strongly related to the improved kinetics of charge transfer and oxygen incorporation processes. Density functional theory calculations show that the surface SrCO3reduces the O2dissociation energy barrier from 1.01 eV to 0.33 eV, thus enhancing the ORR kinetics, possibly through changing the charge density distribution at the LSCF-SrCO3interface.
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Zhongti
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Yang
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Hong
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Zhesheng
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China.
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn and Hefei National Laboratory of Physical Sciences at the Microscale, Synergetic Innovation of Quantum Information & Quantum Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province 230026, P. R. China. xiacr@ustc.edu.cn.
authors.forename: Changrong
authors.initials: C
authors.lastname: Xia