Patterning of Graphene via an In Situ Electrochemical Method using Ni Opal or Inverse-Opal Structures

The development of advanced methods for graphene with nanoscale width and periodic geometries is important to graphene-based electronic and optical devices. Metal inverse opals and opals were used as reliable nanopatterned electrodes for the electrochemical reactions of graphene oxide (GO) films at -0.8 to -1.5 V versus saturated calomel electrode. Graphene with redox patterns was formed by limited reduction time. Reduced GO (RGO) films with deeper surface impress patterns were formed after electrochemical reductions and varied according to the surface geometries of the Ni inverse opals. The resistivity of the RGO using Ni solid films and inverse opals decreased rapidly because a connected RGO formed at the beginning of the reduction. In contrast, the resistivity of RGO reduced by Ni opals did not show a significant decrease in the beginning because of the disconnected reduction. The formed periodic undulations of RGO structures did not show the coupling of optical wavelength, but shifted the stop band of colloidal crystals covered under them.