Abstract
Spinel ferrites with general formula AB2O4 (A indicates any divalent transition metal and B is represents the trivalent iron ions) have versatile applications including from magnetic materials, MRI, catalysis and sensors to energy related applications. Substituted and unsubstituted spinel Co0.8Ni0.2Fe2O4 ferrite particles were synthesized by facile wet chemical route. X-ray diffraction (XRD) patterns confirmed the single phase cubic structure of the un-substituted and substituted Co0.8Ni0.2Fe2O4 nanoparticles. The crystallite size as determined from XRD data by Scherrer's formula was found 18–30 nm. Reduced graphene oxide (rGO) was prepared by Hummer's method that involved the oxidation of graphite into graphite oxide (GO) and then reduction of GO into reduced graphene oxide (rGO). Both GO and rGO were confirmed by XRD, UV–Visible spectroscopy, Raman spectroscopy, X-ray photoelectron (XPS) analysis. All these techniques results confirmed the successful preparation of GO and rGO. The composites of spinel ferrite nanoparticles and rGO were prepared via facile ultra-sonication technique and the composite formation was investigated by scanning electron microscopy (SEM). The electrical and electrochemical studies proved that the substituted spinel ferrite Co0.8Ni0.2Fe2O4 nanoparticles exhibited good DC electrical conductivity as compared to un-substituted ferrite particles. The enhanced DC electrical conductivity thus yielded the good electrochemical energy storage properties of the substituted-ferrite nanoparticles@rGO composites for supercapacitors applications. The fabricated supercapacitor electrodes using prepared materials demonstrated maximum specific capacitance (444.4 F g−1) and capacitance retention of about 75% respectively.