Computational studies of the interactions of oxygen with platinum clusters

Density functional theory is used to compute electronic and thermodynamic interactions between atomic and molecular oxygen and small Pt, clusters (n = 2-6). Binding energies, vibrational frequencies, and charge distributions are reported. Two states are identified for the adsorption of molecular oxygen: the superoxo species (O-2(delta-)) and the peroxo species (O-2(2 delta-)) formed by charge transfer from the metal cluster to the O-2 molecule. An analysis of the adsorbed O-2 dissociation on Pt clusters illustrates the dependence of the activation barrier for dissociation on the metal cluster size.