Adsorption of atomic and molecular oxygen on the LaMnO3(001) surface:: ab initio supercell calculations and thermodynamics

被引：118

作者：

Kotomin, Eugene A. ^{[1
,2
]}

Mastrikov, Yuri A. ^{[1
,2
]}

Heifetsa, Eugene ^{[1
]}

Maier, Joachim ^{[1
]}

机构：

[1] Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany

[2] Latvian State Univ, Inst Solid State Phys, LV-1063 Riga, Latvia

来源：

PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 2008年 / 10卷 / 31期

关键词：

D O I：

10.1039/b804378g

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：

We present and discuss the results of ab initio DFT plane-wave supercell calculations of the atomic and molecular oxygen adsorption and diffusion on the LaMnO3 (001) surface which serves as a model material for a cathode of solid oxide fuel cells. The dissociative adsorption of O-2 molecules from the gas phase is energetically favorable on surface Mn ions even on a defect-free surface. The surface migration energy for adsorbed O ions is found to be quite high, 2.0 eV. We predict that the adsorbed O atoms could penetrate the electrode first plane when much more mobile surface oxygen vacancies (migration energy of 0.69 eV) approach the O ions strongly bound to the surface Mn ions. The formation of the O vacancy near the O atom adsorbed atop surface Mn ion leads to an increase of the O-Mn binding energy by 0.74 eV whereas the drop of this adsorbed O atom into a vacancy possesses no energy barrier. Ab initio thermodynamics predicts that at typical SOFC operation temperatures (similar to 1200 K) the MnO2 (001) surface with adsorbed O atoms is the most stable in a very wide range of oxygen gas pressures (above 10(-2) atm).

引用

页码：4644 / 4649

页数：6

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