Theoretical study on the adsorption of CO and O2 on MgO-supported Pd and Cu atoms

The physical properties of adsorption and co-adsorption properties of CO and O-2 molecules on the MgO-supported Pd and Cu atoms have been studied at the DFT/B3LYP level of theory using the embedded cluster model. The calculations show that the supported Pd atom on the perfect surface is energetically more favorable for adsorbing a CO molecule than an O-2 molecule, with the respective binding energies of 206.5 vs. 84.8 kJ/mol. While such interactions on Pd atom located above an oxygen vacancy of the MgO(100) surface are very weak, due to significant amount of electron charge transferring from the vacancy to Pd atom. In contrast, the supported Cu atom on both types of surfaces prefers to adsorb O-2 molecule, instead of CO molecule, with the O-2 binding energies of 140 similar to 155 kJ/mol. It was found that the binding between the two-coadsorbates for CO+CO, CO+O-2, O-2+O-2 coadsorbed on the supported Pd atom on the perfect surface reduced the admolecule-Pd interactions by the reductive energies of 46 similar to 96 kJ/mol. Such reductions only for O-2+O-2 coadsorbed on the supported Cu atom on both surfaces are considerable with the reductive energies of 50 similar to 71 kJ/mol.