褐铁矿
阴极
钙钛矿(结构)
电负性
氧化物
材料科学
正交晶系
氧气
兴奋剂
化学工程
无机化学
化学
晶体结构
结晶学
物理化学
光电子学
冶金
有机化学
工程类
作者
Xiaoyong Xu,Jie Zhao,Mengran Li,Linzhou Zhuang,Jinxuan Zhang,Sathia Aruliah,Fengli Liang,Hao Wang,Zhonghua Zhu
标识
DOI:10.1016/j.compositesb.2019.107491
摘要
Sealing and stability is the challenge for solid oxide fuel cells (SOFCs) at high temperature. It is crucial to operate SOFCs at a low temperature to avoid these issues. Thus, it is necessary to improve the sluggish oxygen reduction reaction (ORR) activity of cathode. The SrCoO3-δ perovskite with a cubic phase is identified as a potential cathode material for SOFCs due to its high oxygen permeability and reasonable electrical conductivity. However, it readily decomposes into the orthorhombic structured brownmillerite Sr2Co2O5 or hexagonal Sr6Co5O15 during high-temperature sintering resulting in the loss of a significant amount of lattice oxygen. Herein, we partially replace Co with Sc and Ta at SrCoO3-δ to stabilize its cubic perovskite structure and restrain the lattice oxygen loss, thus improving the oxygen-ionic conductivity, and the structural and chemical stability. The synthesized SrSc0.175Ta0.025Co0.8O3-δ (SSTC) cathode achieves a remarkably high ORR performance and an area-specific resistance obtained in this study reaches as low as 0.233, 0.033, and 0.004 Ω cm2 at 500, 600, and 700 °C, respectively. The new Sc and Ta-doped SrCoO3-δ perovskite cathode even present a better ORR activity than the previously reported Sc and Nb-doped SrCoO3-δ cathode. The reason for the improved performance by Ta doping is possible that Ta–O bond is stronger than Nb–O bond and the electronegativity of Ta5+ is lower than that of Nb5+, resulting in a lower valence state of cobalt and a higher oxygen vacancies concentration.
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