Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation

Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density (Formula presented.), a transition from ballistic to diffusive conduction occurs at (Formula presented.) cm (Formula presented.) and the transport gap grows in proportion to (Formula presented.). Considering the potential fluctuation related to the (Formula presented.) puddle, the bandgap of graphene oxide is deduced to be (Formula presented.) meV. The temperature dependence of conductivity showed metal–insulator transitions at (Formula presented.) cm (Formula presented.), consistent with Ioffe–Regel criterion. For graphene oxides at (Formula presented.) cm (Formula presented.), analysis indicated charge transport occurred via 2D variable range hopping conduction between localized (Formula presented.) domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content.