Tuning electronic properties by oxidation-reduction reactions at graphene-ruthenium interface

Mass production of graphene is associated with the growth on catalysts used also in other chemical reactions. We exploit the oxidation-reduction to tailor the properties of single layer graphene domains with incorporated bi-layer patches on ruthenium. Using photoelectron spectromicroscopy techniques, we find that oxygen, intercalating under single layer and making it p-doped by the formation of Ru-Ox, does not intercalate under the bilayer patches with n-doped upper layer, but decorates them under single layer surrounding creating lateral p-n junctions with chemical potential difference of 1.2 eV. O-reduction by thermal treatment in vacuum results in C-vacancy defects enhancing electronic coupling of remained graphene to Ru, whereas in H2, vacancy formation is suppressed. For the domains below 15–25 μm size, after O-reduction in H2, graphene/Ru coupling is restored, while wrinkle pattern produced by O-intercalation is irreversible and can trap reaction products between the wrinkles and Ru surface step edges. In fact, in certain regions of bigger domains, the products, containing H2O and/or its fragments, remain at the interface, making graphene decoupled and undoped.