Investigation of chemical bonding and supercapacitivity properties of Fe3O4-rGO nanocomposites for supercapacitor applications

Iron oxide decorated reduced graphene oxide (Fe3O4/rGO) nanocomposites were synthesized using a one-step chemical reduction method. The XRD results reveal the diffraction planes at 2 theta = 36.53 degrees and 43.04 degrees corresponding to the planes (311) and (400) respectively for Fe nanoparticles and the broadened peak at 26.52 degrees was observed corresponds to plane (002) for rGO which confirmed the formation of Fe3O4 in rGO sheets. FTIR results shows the chemical bonding at around 580.96 cm(-1), 1191.61 cm(-1), 1559.36 cm(-1), 2358.27 cm(-1), 2987.45 cm(-1) and 3360 cm(-1) attributes for the Fe-O, C-O, C=C, C=O, C-H-2 and O-H bonds respectively whereas Raman shift for Fe3O4 was found in the range of 100-800 cm(-1). The I-D/I-G ratios varied from 2.5 to 1.55 as Fe(NO3)(3) concentration increases from 5 mM to 25 mM. The estimated bandgap for rGO and rGO/Fe3O4 are 2.60 eV, and from 2.52 to 2.34 eV respectively as the Fe(NO3)(3) concentration increases from 5 mM to 25 mM. The atomic percentage of Fe(2p), C(1s), and O (1s) was varied as 0.75-7.11 at.%, 86.09-69.58 at.% and 13.16-23.31 at.% as the Fe(NO3)(3) concentration increases from 5 mM to 25 mM. The maximum specific capacitance was achieved at 416 F/g for 25 mM of Fe3O4/rGO nanocomposite with cyclic stability of 88.57% at a current density of 5Ag(-1) over 1000 cycles. Hence, Fe3O4/rGO nanocomposite can be considered as a good candidate for the supercapacitor electrode applications.