Electrical and Structural Properties of CVD-Graphene Oxidized Using KMnO4/H2SO4 Solution

We report the electrical properties of graphene grown via chemical vapor deposition (CVD-graphene) and oxidized using a KMnO4/dilute H2SO4 mixture. CVD-graphene was successfully oxidized without any pores or peeling off from the substrates. When the H2SO4 concentration was increased, the electrical resistance of the oxidized graphene (OG) increased. In particular, OG-20 shows a nonlinear current–voltage curve similar to that of a diode owing to direct tunneling through the interfaces between the nanosized sp2 and sp3 regions. The changes in electrical properties occurred because of structural evolution. As the H2SO4 concentration increased, the number of oxygen functional groups (epoxide/hydroxyl and carboxyl groups) in the OG increased. In addition, a reduction in the average distance between defects in the OG was determined using Raman spectroscopy. Oxidation using a KMnO4/dilute H2SO4 mixture results in CVD-graphene with modified electrical properties for graphene-based applications.