Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (09): 815-818.doi: 10.3866/PKU.WHXB20030907

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O2 Adsorption on MgO(001) Surface with Oxygen and Magnesium Vacancies

Xu Yi-Jun;Li Jun-Qian;Zhang Yong-Fan   

  1. State Key Laboratory of Structural Chemistry, Department of Chemistry, Fuzhou University, Fuzhou 350002
  • Received:2003-01-16 Revised:2003-04-16 Published:2003-09-15
  • Contact: Li Jun-Qian

Abstract: The adsorption of O2 at oxygen vacancy site (F, F+ or F2+site) and magnesium vacancy site (V, V- or V2- site) has been studied using cluster models embedding in a large array of point charges coupled to density functional method at B3LYP/6-31G(d) level. The value of point charges is determined by the self-consistent technique. The calculated results indicate that the MgO(001) surface with oxygen vacancies has more excellent catalyst structure contributing to the adsorptive-decomposition of O2 in comparison with the low-coordinated corner site in the previous study. The adsorption energies for O2 adsorbed on MgO(001) surface with oxygen vacancies are larger than those on MgO(001) surface with magnesium vacancies. Moreover, the MgO(001) surface with magnesium vacancies hardly exhibits catalytic reactivity toward O2 decomposition. The Mülliken charge analysis illustrates that, for O2 adsorption on MgO(001) surface with oxygen vacancies, the electrons are transferred from the substrate to the adsorbed O2 and occupy the anti-bonding orbital, π* of O2. Thus, the O-O bond strength is weakened. Potential energy curve shows that the energy barrier is considerably decreased for O2 adsorbed at oxygen vacancy site of MgO(001) surface when compared to that at corner site in our previous study.

Key words: O2, MgO(001) surface, Oxygen vacancy, Magnesium vacancy, Adsorption, Density functional theory, Cluster models