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 n 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 δ - ) and the peroxo species (O 2 2δ- ) 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.