Immobilization of Au Nanoclusters Supported on Graphite: Molecular Dynamics Simulations

We present a new approach to retard undesirable cluster aggregation. Using molecular dynamics simulations, we found that a large Au cluster that collides with a small cluster of metals other than Au has a locally distorted structure. Because of the lattice mismatch with a graphite surface, the distorted region of the Au cluster acts as a pinning center during the cluster diffusion process. Through the pivotal rotation caused by the pinning center, the Au cluster significantly reduces lateral diffusion. We also found that the most effective factor in the distortion of the structure is the difference in atomic size. The results of an AuNi system which has a large difference in atomic size confirm that a collision with a small Ni cluster reduces the diffusion of the large Au Cluster. On the basis of these results, we expect that the use of cluster collision leads us to promising applications in the production of immobilized clusters.