Monolayer graphene/NiO nanosheets with two-dimension structure for supercapacitors

In this paper, graphene oxide (GO) synthesized from the modified Hummer method is used directly to fabricate unique two-dimension graphene/NiO composite material. Nickel ions are adsorbed on both sides of GO based on self-assembly by the electrostatic interactions of two species, forming the monolayer graphene/NiO sheet. The as-prepared composite is characterized using X-ray diffraction (XRD), Raman, SEM, TEM, Energy Dispersive Spectrometer (EDS) analysis and nitrogen adsorption/desorption. The results demonstrate that the NiO nanoparticles (5-7 nm) is uniformly dispersed on the surface of graphene, which greatly increases the surface area of the composite (134.5 m(2) g(-1)). This two-dimensional structure enhances supercapacitive performance with a high specific capacitance of 525 F g(-1) at a current density of 200 mA g(-1). A capacity retention of 95.4% can be maintained after 1000 cycles, suggesting its promising potential in supercapacitors.