Facile growth of hollow porous NiO microspheres assembled from nanosheet building blocks and their high performance as a supercapacitor electrode

Self-assembled hollow flowerlike NiO as a promising supercapacitor material has been fabricated by a facile hydrothermal process and the formation mechanism of the flowerlike morphology is investigated. The structure and morphology of the NiO samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) etc. and the surface area of the NiO sample was analyzed by measuring its N-2 adsorption-desorption isotherms. The results indicated that the addition of P123 inhibited the grain growth of NiO, and with the assistance of P123, the nanoparticles assembled into flowers. The electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The results suggest that the flowerlike NiO has good electrochemical reversibility and displays superior capacitive performance with large capacitance (619 F g(-1)), as well as excellent cycling stability after 1000 cycles.