First-principles calculations of zirconium-coated graphene sheets for various coverages and geometries were reported. Adsorption properties, such as distances and the Zr/graphene binding energies were calculated. Upon increasing the Zr/C coverage ratio, the binding energies showed that the Zr atoms have a trend to cluster. The most stable Zr/C coverage corresponded to 0.375, which has no stress between the zirconium and graphene layer. The Zr-graphene binding involved charge transfer to graphene which came from the 5s orbital of Zr and depended upon the coverage. The diffusion-energy barriers on graphene for the single atom and the Zr3 trimer were also calculated and it was seen that the Zr3 cluster was a faster diffusion unit. It was also estimated that the Zr diffusion energy between two substitutional positions was at least 4eV, which was large enough to fix Zr atoms bound to C vacancies at actual temperatures in high-resolution transmission electronic microscopy experiments.

Ab initio Calculations of Zirconium Adsorption and Diffusion on Graphene. Sanchez-Paisal, Y., Sanchez-Portal, D., Ayuela, A.: Physical Review B, 2009, 80[4], 045428