Preparation of scale-like nickel cobaltite nanosheets assembled on nitrogen-doped reduced graphene oxide for high-performance supercapacitors

Ultrathin scale-like nickel cobaltite (NiCo2O4) nanosheets supported on nitrogen-doped reduced graphene oxide (N-rGO) are successfully synthesized through a facile co-precipitation of Ni2+ and Co2+ in the presence of sodium citrate and hexamethylenetetramine and subsequent calcination treatment. The composition and morphology of NiCo2O4 nanosheets@nitrogen-doped reduced graphene oxide (denoted as NiCo2O4 NSs@N-rGO) were characterized by Scanning electron microscope, Transmission electron microscope, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller and thermogravimetric analysis. The thickness of NiCo2O4 nanosheets anchored on the reduced graphene oxide is around 4 nm. The capacitance of NiCo2O4 NSs@N-rGO is evaluated by cyclic voltammogram and galvanostatic charge/discharge with the result that the NiCo2O4 NSs@N-rGO could deliver a specific capacitance of 1540 F g−1 after 1000 cycles at 10 A g−1.