Ginger extract (GE) was employed for the reduction of graphene oxide (GO) by refluxing in an aqueous medium with different reduction times. The reduced GO was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) to investigate structural, chemical bonding and functional groups, respectively. The XRD results reveal that the maximum reduction GO was observed at 12 h. The scanning electron microscopy (SEM) images showed the formation of a thin sheet-like structure for ginger reduced graphene oxide (GRG12). The electrochemical properties of GRG samples were further evaluated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS). The GRG12 showed the highest specific capacitance value of 99.61 F g$^{-1}$ at a scan rate of 5 mV s$^{-1}$ with cycling stability of 98% after 1000 cycles. This study demonstrates the potential of GE for the reduction of GO and efficiency of the reduced product for application in supercapacitors.

Iron oxide (Fe$_3$O$_4$)/reduced graphene oxide (rGO)/polyvinylpyrrolidone (PVP) nanocomposite films with varying iron weight percentages were prepared by electrospinning spray method on glass, aluminium foil and Si (100)substrate. The size of Fe$_3$O$_4$/rGO/PVP composite particles varied between 0.75 and 1.35 ${\mu}$m on the surface of the graphene sheet. The diffraction peaks at 36.77°, 47.06°, 52.98° and 61.34° confirmed the plane (311), (400), (422) and(440) of the Fe$_3$O$_4$ crystal lattice, respectively. The broad peaks around 26.6° and 43.47°correspond to the planes (002) and (102) for the rGO sheet in the Fe$_3$O$_4$/rGO/PVP nanocomposite films. The defect parameter, $I_D$/$I_G$ ratio varied from 0.17 to 0.34 with 15 and 25wt% Fe$_3$O$_4$ content, respectively, indicates the decreasing of defects in the Fe$_3$O$_4$/rGO/PVP network. The minimum value of $E_{corr}$ and $I_{corr}$ are 0.18 V and 4.76 ${\mu}$A, respectively.

Green synthesis of reduced graphene oxide (rGO) was done using three different plant extracts, such as banana, mango leaves and potato, as the reducing agent. The field-emission scanning electron spectroscopy revealed the formation of thin layers in the morphology of rGO reduced with the green extracts. The X-ray diffraction patterns reveal that the peak for GO (001) appeared at 2${\theta}$ = 11.01°and in rGO broad peak appeared for the (002) plane at ${\sim}$21°–26°. TheFourier transform infrared spectroscopy graphs showed the peaks for C=C at ${\sim}$1571 cm$^{-1}$, which confirmed the formation of the graphene backbone structure. Raman analysis showed the characteristic G band for the sp$^2$ carbon structureof rGO. The cyclic voltammetry study revealed that the rGO-b exhibits the most significant value of specific capacitance of 176 F g$^{–1}$ at a 5 mV s$^{–1}$ scan rate.