AB-INITIO STUDY OF INTERACTION BETWEEN THE OH HYDROXYL AND PT-N (N=1-10) CLUSTERS

The different Pt-n-OH (n = 1-10) models have been calculated by ab ini tio method. The result shows that the binding energy of the Pt-OH vari es with adsorption sites (atop, bridge and hollow) in range of - 1.0 t o - 10.7 eV. It is also found that there exists strong repulsion among the surface OH species and differently charged hydroxyl species can b e formed on the Pt surface (the formal charge varies in range of +0.05 5 to -0.660). On the basis of the calculation result, it is concluded that the variation of the activation energy with the O-2/H-2 ratio res ults from the manifold bond strengths of the Pt-n-OH (n = 1-10) and th e interaction among the adsorbates (OH), which elucidates the experime ntal observation very well.