Effects of Cluster Size on Platinum–Oxygen Bonds Formation in Small Platinum Clusters

Abstract

We present the results of density functional theory calculation in oxygen dissociative adsorption process on two types of isolated platinum (Pt) clusters: Pt₄ and Pt₁₀, by taking into account the effect of cluster reconstruction. The strength of Pt–Pt bonds in the clusters is mainly defined by d–d hybridization and interstitial bonding orbitals (IBO). Oxygen that adsorbed on the clusters is weakening the IBO and thus inducing geometry reconstruction as occurred in Pt₁₀ cluster. However, cluster that could undergo structural deformation is found to promote oxygen dissociation with no energy barrier. The details show that maintaining well-balanced of attractive and repulsive (Hellmann–Feynman) forces between atoms is considered to be the main key to avoid any considerable rise of energy barrier. Furthermore, a modest energy barrier that gained in Pt₄ cluster is presumed to be originate from inequality of intramolecular forces between atoms.