Destruction of graphene by metal adatoms

The formation energies for mono- and bivacancies in graphene in the presence of adatoms of various metals and small metallic clusters have been calculated. It is shown that transition metal impurities such as iron, nickel, and, especially, cobalt reduce dramatically the vacancy formation energies whereas gold impurities have almost no effect on characteristics of the vacancies. These results highlight that special measures are required in order to protect graphene from damage by transition metal leads.