Theoretical study of CO2 activation on Pt(111) induced by coadsorbed K atoms

The adsorption of CO2 on the clean and potassium-precovered Pt(111) surface has been studied by means of the cluster model approach within the hybrid B3LYP density functional theory-based method. On the clean surface, CO2 is undistorted and weakly bound. The equilibrium position of this physisorbed species appears at a rather large distance from the surface. However, when coadsorbed K atoms are included in the model, a chemisorbed, bent CO2 speci es on top of a surface Pt atom is found. The presence of the coadsorbed K i s found to be necessary to promote CO2 chemisorption and activation, the ke y step in activating the CO2 molecule being a direct interaction with the c oadsorbate. In addition, the calculated vibrational frequencies for this ch emisorbed species are in agreement with available experimental data. (C) 20 00 Elsevier Science B.V. All rights reserved.