Molecular Dynamics Simulations of the Interactions between Platinum Clusters and Carbon Platelets

Molecular dynamics simulations have been performed with two reactive force fields to investigate the structure of a Pt₁₀₀ cluster adsorbed on the three distinct sides of a carbon platelet. A revised Reax force field for the carbon−platinum system is presented. In the simulations, carbon platelet edges both with and without hydrogen termination have been studied. It is found that the initial mismatch between the atomic structure of the platelet egde and the adsorbed face of the Pt₁₀₀ cluster leads to a desorption of a few platinum atoms from the cluster and the subsequent restructuring of the cluster. Consequently, the average Pt−Pt bond length is enlarged in agreement with experimental results. This change in the bond length is supposed to play an important role in the enhancement of the catalytic activity, which is demonstrated by studying the changes in the bond order of the platinum atoms. We found an overall shift to lower values as well as a loss of the well-defined peak structure in the bond-order distribution.