Activation of H2 Molecules on Platinum and Platinum–Vanadium Clusters: DFT Quantum Chemical Modeling

Abstract

The activation of H₂ molecules by Pt₄ and Pt₃V clusters was studied by the nudged elastic band (NEB) DFT/PBE0/def2tzvp quantum chemical method with construction of minimum energy paths (MEPs). In the case of Pt₄ and Pt₃V clusters, barrier-free dissociative adsorption of H₂ molecules occurs at the platinum centers, while molecular adsorption of hydrogen occurs on the vanadium atom in Pt₃V with a slight weakening of the H−H bond, but without its breaking. The specific features of coordination of H₂ molecules are explained at the level of the MO method. Migration of the H atom from one cluster metal center to another in the model clusters (as probably in the case of hydrogen spillover) occurs at low activation barriers in the direction of the displacement vector corresponding to the normal vibrations of the system in the transition state. A significant role of Pt−H−Pt and V−H−Pt bridging groups in hydrogen migration has been revealed: they facilitate the transition of H atoms from one metal center of the cluster to another.