钙钛矿(结构)
电极
材料科学
X射线光电子能谱
氧化物
电化学
氧气
空位缺陷
掺杂剂
分析化学(期刊)
化学工程
无机化学
化学物理
兴奋剂
化学
物理化学
光电子学
结晶学
冶金
有机化学
色谱法
工程类
作者
Mingi Choi,Won Young Lee
标识
DOI:10.1016/j.cej.2021.134345
摘要
Thermally driven chemical instability at the perovskite electrode is one of the biggest challenges to overcome in the development of sustainable solid oxide fuel cells. At elevated temperatures, the A-site dopant (typically Sr) segregation toward the surface of the perovskite electrode induces the substantially nonstoichiometric surface with the formation of insulating Sr-rich phases by the electrostatic interactions between oxygen vacancies (Vo∙∙) and doped Sr (SrLa'), deteriorating the oxygen reduction reaction kinetics. Herein, we report the precise tuning of the oxygen vacancy concentration at the perovskite surface in a Gd0.1Ce0.9O2−δ (GDC)/La0.6Sr0.4CoO3−δ (LSC) heterostructured electrode by rearranging the oxygen vacancies near the interface, resulting in an ∼15-fold increase in the surface exchange coefficient after long-term operation at 650 °C for 100 h. The depth profiles of the charged defects obtained by X-ray photoelectron spectroscopy revealed that the oxygen vacancy concentration at the perovskite surface can be controlled by the amount of vacancy acceptable sites in the GDC layer. This strongly affects the chemical and electrochemical stabilities after long-term operations. Our results demonstrate the potential of tuning the defect concentration in heterostructured electrodes to achieve highly sustainable electrodes for the long-term operations at elevated temperatures.
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