Atomic-Scale Investigation of Highly Stable Pt Clusters Synthesized on a Graphene Support for Catalytic Applications

The synthesis and binding of highly stable platinum clusters supported on epitaxial graphene, grown on 6H-SiC(0001) substrates, were investigated by scanning tunneling microscopy (STM) and spectroscopy (STS). These Pt nanoclusters form uniformly on both mono- and bilayer sheets of graphene. Unlike most metals that simply diffuse on the inert graphene substrate, these Pt clusters appear to attach to the graphene through chemical bonding, as strong electron scattering and high thermal stability are observed. The thermal stability of the deposited Pt atoms was demonstrated by annealing the sample in situ up to 700 degrees C. The Pt clusters were not significantly changed by agglomeration or atom detachment. Further annealing at 1250 degrees C led to desorption of the Pt clusters from the monolayer of graphene, whereas the Pt clusters on the bilayer graphene remained and may have intercalated between the graphene sheets. The goal of this study was to explore the utilization of ideal graphene (not graphene oxide or reduced graphene) as a support for nanoparticle catalysts.