Rh nanoclusters on graphene template

Several studies have clearly demonstrated that atomic aggregates in the nanometer size range, that is, formed by dozens or hundreds of atoms, present remarkably different properties with respect to their bulk crystalline counterparts. This is partly due to finite size effects influencing the local electronic structure of the nanocluster atoms.
We have presented a thorough study on graphene-supported Rh nanocluster assemblies grown in register with the template surface of graphene/Ir(111) and their geometry dependent electronic structure obtained by combining high-energy resolution core level photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory.
By carefully selecting the Rh coverage and the annealing
temperature, we have demonstrated the possibility to control the density of edge and facet atoms and the nanocluster arrangement in superlattices. In particular, growth conditions of the nanoclusters exhibit a remarkably high degree of crystallinity.

By comparing measured and calculated core electron binding energies, we identify edge, facet, and bulk atoms of the nanoclusters. We describe how small interatomic distance changes occur while varying the nanocluster size, substantially modifying the properties of surface atoms. The properties of under-coordinated Rh atoms are discussed in view of their importance in heterogeneous catalysis and magnetism.
Our approach gives access to detailed information on fundamental properties at the nanoscale and may help pave the road for attractive technological applications.