CO adsorption on pd atoms deposited on MgO, CaO, SrO and BaO surfaces: density functional calculations

The adsorption properties of CO molecules adsorbed on Pd atoms supported on various sites of MgO, CaO, SrO and BaO surfaces have been studied by means of a density functional cluster model approach. Clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surface, and ions that were the nearest neighbors to the adsorption site were allowed to relax to equilibrium. The metal Pd atoms are stabilized with different binding energies on the examined defect-free and defect-containing surfaces of the oxide supports. We considered oxide anions, neutral and charged anion vacancies located at the regular (001) surfaces. CO is used as a probe molecule to characterize where the Pd atoms are located. This is done by analyzing how the Pd-CO binding energy changes as a function of the substrate site, where the Pd atom is bound, and on the basicity of the oxide support. (C) 2008 Elsevier B.V. All rights reserved.