THEORETICAL STUDY OF N2O ADSORPTION AND DECOMPOSITION AT REGULAR AND DEFECT SITES OF MgO (001) SURFACE

Abstract

The adsorption of N 2 O at regular and defect sites of MgO (001) surface has been studied systematically using cluster models embedded in a large array of point charges by density functional method. The calculated results show that the MgO (001) surface with oxygen vacancies exhibits high catalytic reactivity toward N 2 O adsorptive-decomposition at variance with the regular MgO surface or the surface with magnesium vacancies. Much elongation of O–N bond of N 2 O after adsorption at oxygen vacancy site with O end of N 2 O down indicates that O–N bond has been broken with concurrent production of N 2, leaving a regular site instead of the original oxygen vacancy site (F center). Besides, the MgO (001) surface with magnesium vacancies hardly exhibits catalytic reactivity. It can be concluded that N 2 O dissociation is likely occurred at MgO (001) surface oxygen vacancy sites, which is consistent with the generally accepted viewpoint in the experiment.