Influence of various concentrations of cetyltrimethylammonium bromide on the properties of nickel oxide nanoparticles for supercapacitor application

In this paper, the impact of the crystallite sizes of nickel oxide nanoparticles (NiO NPs) on their efficiency for electrochemical capacitors (EC) has been investigated. NiO NPs were prepared without and with low and high concentrations (0.02M and 0.1M) of cetyltrimethylammonium bromide (CTAB) using the hydrothermal process that represent NiO, NiO-1, NiO-2, respectively. The crystallite size of NiO, NiO-1, NiO-2 NPs was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis. The thermogravimetry/differential thermal analysis (TG/DTA) was used to investigate the thermal observation of as-prepared precursor to transform as NiO NPs. HRTEM revealed spherical seed-like morphologies, which consist of aggregated NiO-1 NPs with an average particle size of 9nm. The NiO-1 shows the large specific capacitance value of 168Fg-1 at a current density of 0.5Ag-1 compared with other NiO and NiO-2 NPs. The study suggests that the low concentration of surfactant CTAB of NiO NPs plays an important role in supercapacitor applications because of the smaller crystallite sizes of the materials as well as a large number of active sites for faradic reaction.