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| - Computational Modeling Study of the Solubility of Cerium at LaCoO3 Perovskite Surfaces
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| Abstract
| - Atomistic computational modeling of the surface structure of the catalytically active perovskite LaCoO3 is reported in order to understand the effect of doping with tetravalent cerium cations, which enhances high-temperature catalytic oxidation processes such as CH4 combustion. In particular, solution energies have been calculated for the important (100) and (110) low index crystal faces. Three reactions for Ce4+ doping have been considered, two of which involve creation of La3+ vacancies or Co3+ reduction in stoichiometric LaCoO3, whereas the third relates to oxygen vacancy filling in reductively nonstoichiometric LaCoO3. We show that Ce4+ is considerably more soluble at the surface than in the bulk to a level of ∼5 atom %, which agrees with experimental estimates by X-ray diffraction. We predict that the nature of the defect compensating reaction will be strongly dependent on oxygen partial pressure, and hence on the preparation conditions. The effect of Ce4+ doping on catalytic oxidation is discussed in terms of the relative redox behavior of Ce4+ and Co3+ and the availability of oxygen vacancies and surface lattice oxygen.
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| Alternative Title
| - Solubility of Cerium at LaCoO3 Perovskite Surfaces
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