Synthesis of NiO nanospheres with ultrasonic method for supercapacitors

NiO nanospheres have been synthesized by using magnetic stirring and ultrasound methods. The structure and morphology of synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. The results show the NiO nanospheres prepared by the ultrasonic method are far less than that prepared by the stirring method. Moreover, in the presence of surfactant, the average diameter of NiO nanospheres prepared by the ultrasonic method is only 1-3 nm. The capacitance of NiO electrodes was investigated with cyclic voltammetry. The NiO prepared by the ultrasonic method exhibited higher specific capacitance of ~260 F g−1 at 1 A g−1 current density.