One pot reflux synthesis of reduced graphene oxide decorated with silver/cobalt oxide: A novel nano composite material for high capacitance applications

We report a simple and novel synthesis of reduced graphene oxide/silver/cobalt oxide novel nanocomposites (rGO-SCO) as an electrode material for supercapacitor applications by one-step reflux method. The graphene oxide was initially reduced to reduced graphene oxide (r-GO) by simple heat treatment in the presence of reducing agent(NaBH4). The prepared r-GO was refluxed with the appropriate quantities of cobalt nitrate and silver nitrate for overnight to get high surface area r-GO decorated with silver / cobalt oxide nanocomposite material. In the prepared nanocomposite, r-GO acts as a substrate to hold the oxides which in turn enhance the conductivity of the prepared nanocomposite material. The nanocomposites were subjected to the physical characterization, such as XRD,which reveals the confirmation and formation of the prepared composites with the well crystallinity nature and crystallite size of 3.5 nm. FTIR confirms the removal of epoxy groups in reduced graphene oxide and metal -oxygen vibration band in the composite. Surface morphology was analysed by SEM and HR-TEM, which discloses that the reduced graphene oxide is being retained in the composite and promotes ion diffusion process. EDAX confirms the exact elemental composition in the composite. The electrochemical performance of the prepared rGO-SCO composites was examined by cyclic voltammetry, charge-discharge and A.C. impedance analysis. The maximum specific capacitance obtained on rGO-SCO nanocomposite was 979.52 Fg(-1) at a current density of 0.25 Ag-1 along with high cycling stability of 94.05% for 1000 cycles.