Interaction of CO with PdAu(111) and PdAu(100) bimetallic surfaces: A theoretical cluster model study

Structural parameters, binding energies, and bonding mechanism of CO molecules on PdAu(111) and PdAu(100) surface alloys have been investigated at the density functional level by employing a cluster model approach. Cluster models have been constructed to represent second-neighbor Pd pairs on both the exposed gold surfaces, given that special ensembles are able to confine reactants in a small region of bimetallic catalysts. Analysis of the cluster size dependence of the chemisorption properties has been carried out together with the study of the influence of exchange correlation functional and basis set quality. An accurate description of the bonding mechanism of CO on top of Pd monomers surrounded by gold atoms has been achieved by an atom-projected description of the surface bond. The remarkable agreement of computed results with available experimental information and previous periodic supercell calculations clearly indicates that the adopted cluster models are suitable for chemisorption studies on PdAu surface alloys. © 2008 American Chemical Society.