Graphene is a two-dimensional sheet of sp 2 hybridized carbon atoms, which can be viewed as an extra-large polycyclic aromatic molecule. It has stimulated research interest owing to its ultralarge surface area, excellent conductivity, high mechanical stiffness, chemical inertness 1-3 , good biocompatibility 4 and low manufacturing cost 5. These unique properties of graphene hold great promise for potential applications in various fields such as nanoelectronics 6,7 , nanocomposites 8,9 , supercapacitors 10,11 , electrochemical devices 12 , catalysis 13 , sensors 14 , batteries 15 and dye-sensitized solar cell 16 , etc. Graphene-based applications undoubtedly need low-cost, high quality and large-scale production of graphene. Up to now, some approaches have been developed to prepare graphene, such as: micromechanical exfoliation of graphite with Scotchtap 1 , chemical vapor deposition on metal substrates 17 , epitaxial growth on electrically insulating surface 18, 19 and the reduction of graphene oxide (GO) 20,21 , which can be prepared from natural graphite by the modified Hummers' method 22,23. Among these methods, the reduction from graphene oxide is the most realistic approach for low-cost and gram-level production of graphene. Especially, the electrochemical reduction of graphene oxide (EG) coated on glassy carbon electrode (GCE) surfaces is a promising route for preparing graphene-modified GCE because it is green, fast, low cost and more effective than chemical and
