Enhanced one dimensional mobility of oxygen on strained LaCoO3(001) surface

被引：69

作者：

Han, Jeong Woo ^{[1
]}

Yildiz, Bilge ^{[1
]}

机构：

[1] MIT, Lab Electrochem Interfaces, Dept Nucl Sci & Engn, Cambridge, MA 02139 USA

来源：

JOURNAL OF MATERIALS CHEMISTRY | 2011年 / 21卷 / 47期

基金：

美国能源部; 美国国家科学基金会;

关键词：

LAMNO3-BASED CATHODE MATERIALS; OXIDE; DIFFUSION; PEROVSKITE; EXCHANGE; TRANSPORT; REDUCTION; CONDUCTION; CHEMISTRY; INSIGHTS;

D O I：

10.1039/c1jm12830b

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Mechanisms by which lattice strain alters the oxygen reduction reaction (ORR) kinetics are important to understand in order to increase the ORR activity of solid oxide fuel cell cathodes. Here we assess the mechanistic and quantitative effects of strain on oxygen diffusion on the LaCoO3(LCO)(001) surface using density functional theory calculations. Planar tensile strain is found to reduce the migration barrier of oxygen vacancy anisotropically on the LCO(001) surface, inducing an enhanced mobility along the [1 (1) over bar0] direction and a suppressed mobility along the [110] direction. The increase of space around Co that the oxygen (vacancy) traverses with a curved path is the cause of the enhanced mobility along the [1 (1) over bar0]. The increasing octahedral distortions with planar tensile strain inhibit the migration of oxygen vacancy along the [110] direction. Furthermore, the mobility of the adsorbed oxygen atom is suppressed with increasing strain due to its stronger adsorption on the surface. On the basis of rate theory estimates, the significantly lower energy barrier for oxygen vacancy diffusion is expected to dominate the other degrading factors and actually accelerate the ORR kinetics on LCO(001) up to 3% strain. The insights obtained here are useful for designing strategies to control the desired anisotropic and uni-directional oxygen transport along strained hetero-interfaces.

引用

页码：18983 / 18990

页数：8

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