Simulation of growth process of Pt-particles - First-principles calculations

Abstract

First-principles calculations have been applied to investigate the interactions between Ptn (n = 1 ∼ 4) clusters and a graphene sheet as models of Pt/C fuel-cell catalytic electrodes. A Pt atom is stably adsorbed on the bridge site between two carbon atoms with the adsorption energy of about 2eV. For the case of Pt2, both of the Pt atoms are adsorbed on the bridge site. For the case of Pt3, the triangular cluster is more stable than the linear cluster. For the case of Pt4, the tetrahedral cluster is more stable than the planar cluster. The adsorption energies on the surface without defects are 0.55 eV/adatom for Pt2 and 0.05 eV/adatom for Pt3. The interaction energy between the Pt cluster and the graphite surface per Pt atom becomes weaker as the number of Pt atoms increases. The adsorption energy for a Pt atom on the vacant site is 8.00 eV/adatom, which is stronger than the formation energy of a Pt-Pt bond (about 2 eV/bond) for small clusters. © 2008 IOP Publishing Ltd.