Issue 31, 2008

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

Abstract

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 O2 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 (∼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).

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

Article information

Article type
Paper
Submitted
14 Mar 2008
Accepted
12 May 2008
First published
20 Jun 2008

Phys. Chem. Chem. Phys., 2008,10, 4644-4649

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

E. A. Kotomin, Y. A. Mastrikov, E. Heifets and J. Maier, Phys. Chem. Chem. Phys., 2008, 10, 4644 DOI: 10.1039/B804378G

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