ACS Nano 6, 9551–9558 (2012)

Credit: © 2012 ACS

Although exfoliation is still the most popular method for producing graphene, its epitaxial growth is the preferable route for large-area fabrication of graphene-based devices or spectroscopic studies. Such epitaxial growth can be routinely achieved on various substrates, such as transition metal surfaces or SiC, but the interaction of the substrate with graphene usually perturbs the monolayer's characteristic and desirable electronic properties. Silvano Lizzit and colleagues now show that intercalation of oxygen through a complete graphene layer grown on Ir(111) can decouple the monolayer from its substrate and restore its usual electronic structure. An intact, entirely free-standing graphene monolayer can be produced by this process, which at present works at a specific temperature and relatively high oxygen pressure. The whole process can also be reversed by de-intercalating and desorbing the oxygen. In this case, the original electronic properties of the graphene on Ir(111) are restored, but with a moderate etching of the graphene lattice, rendering subsequent oxygen intercalations easier and at progressively lower pressures and temperatures.