Nucleation and growth of monodispersed cobalt nanoclusters on graphene moiré on Ru(0001).

Monodispersed Co nanoclusters have been grown on a graphene moiré on Ru(0001) at room temperature. Scanning tunneling microscopy measurements showed that the Co clusters nucleate at both the fcc and hcp regions. Co forms finely dispersed small three-dimensional (3D) clusters on graphene/Ru(0001), and a defined long-range ordering of Co nanoclusters with increasing coverage is not observed. The size distribution of the clusters is narrow and the size of the clusters is tunable. The absorbed Co begins to intercalate between the graphene layer and the Ru(0001) substrate when annealing the sample at temperatures up to about 473 K.