Insight into electrical conductivity of graphene and functionalized graphene: Role of lateral dimension of graphene sheet

Exfoliated graphene were obtained from SDS mediated exfoliation of graphite. The exfoliated graphene (G(exf)-SDS) were further subjected to functionalization to obtain reduced graphene (r-GO), acid chloride functionalized graphene oxide (GO-COCl), ester functionalized graphene oxide (GO-COOR), and amide functionalized graphene oxide (GO-CONH2). The impedance measurements were done on functionalized graphene by a simple layer-by-layer (LbL) assembly technique on silicon wafer substrate using chitosan as cationic binder. Further, the role of lateral dimension of the graphene sheet in a.c conductivity was also studied. It was observed that introduction of bulky groups in the graphene sheets may lead to the band gap opening which is responsible for lower a.c conductivity in case of functionalized graphene. Moreover sheet resistance values were determined for graphene and functionalized graphene. (C) 2015 Elsevier B.V. All rights reserved.