Oxygen adsorption at La1−xSrxMnO3(001) surfaces : predictions from first prin- ciples
The interaction of atomic and molecular oxygen with MnO2- and La(Sr)O-terminated (001) surfaces of Sr-doped LaMnO3 has been studied using the B3LYP hybrid exchange-correlation functional within the framework of density functional theory (DFT). Using the obtained binding energies in conjunction with the ab initio thermodynamics we predict that adsorbed O atoms stabilize the surface of an LSM cathode at typical SOFC working conditions (T=1100 K, pO2=0.2 p0). The most favorable oxygen adsorption sites have been found to be atop surface Mn atoms on the MnO2-terminated surface and on the hollow positions of the La(Sr)O-terminated LSM(001) surface. An O2 molecule adsorbed at a hollow position of the La(Sr)O-terminated surface is readily dissociated, which adds a substantial contribution to the ionic transport at the LSM surface.
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