The adsorption of CO at normal and defective sites on the MgO(001) surface was studied theoretically by using embedded cluster models. The values of the embedded point charges were determined by using the self-consistent charge technique. The results indicated that the CO adsorption energy at normal sites of the MgO(001) surface agreed well with recent experimental data. The frequency shifts of CO for regular 5-coordinated terrace, low 4-coordinated edge and 3-coordinated corner sites, via C bound to cationic centers of the MgO(001) surface were also close to experimental values. The adsorption of CO at a MgO(001) surface with neutral and charged O vacancies, Fs, Fs+ and Fs2+ centers, was also investigated. The results showed that a MgO(001) surface with a neutral O vacancy was probably a good catalytic structure for CO adsorptive decomposition. This result was consistent with a previous study, performed by using a different method. By analyzing the bond component of Mg–C, it was found that the basic reason why the C–O bond strength was weakened or strengthened was competition between 4σ* lone-pair electrons and 5σ electrons of CO which transferred from the adsorbate to the substrate simultaneously.

CO Adsorption on MgO(001) Surface with Oxygen Vacancy and its Low-Coordinated Surface Sites - Embedded Cluster Model Density Functional Study Employing Charge Self-Consistent Technique. Y.Xu, J.Li, Y.Zhang, W.Chen: Surface Science, 2003, 525[1-3], 13-23