Synthesis of shape-controlled NiO-graphene nanocomposites with enhanced supercapacitive properties

Flowerlike and polyhedral NiO-graphene nanocomposites have been successfully synthesized using a facile hydrothermal method. The formation mechanism of the two nanocomposites with different morphologies has been studied. The resulting products are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopic analysis (XPS), thermogravimetry (TG), and the Brunauer-Emmett-Teller (BET) method. The prepared NiO-graphene nanocomposites with different shapes can be used for supercapacitor electrode materials. Through electrochemical tests, the flowerlike NiO-graphene composite shows higher specific capacitance than that of the polyhedral one with a specific capacitance as high as 500 F g(-1) at a scan rate of 5 mV s(-1) while the polyhedral NiO-graphene composite delivers better long-term cycle stability with 84% specific capacitance remaining after 3000 cycles in a 1 M KOH electrolyte.