Search

Freestanding porous Co9S8 nanoneedle bundles arrays on Ni foam were in-situ synthesized by a facile ion exchange reaction and were directly used as the electrode for supercapacitors. The structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) were adopted to evaluate the electrochemical property of the porous Co9S8 nanoneedle bundles arrays electrode in 3 mol/L KOH solution. The results show that the specific capacitance of the porous Co9S8 nanoneedle bundles arrays is 1400 F·g-1 at a current density of 4 A·g-1 and the arrays exhibit good cycling stability. The excellent electrochemical performance can be ascribed to the porous nanostructure of Co9S8 nanoneedle bundles arrays and the 3D conductive nickel foam, which can increase the contact areas between electrode and electrolyte and improve the conductivity of the whole electrode.

We report a facile and efficient strategy for the preparation of graphene-Ag2Se nanocomposites. The reduction of graphene oxide (GO) to graphene was accompanied by the formation of Ag2Se particles on the surface of graphene nanosheets. The results of X-ray diffraction (XRD) and Fourier transform infrared (FTIR) confirmed the efficient reduction of GO. Transmission electron microscopy (TEM) images of the sample revealed the morphology of the architecture of graphene-Ag2Se hybrid. Photoluminescence (PL) measurement was further employed to study the optical properties of the nanocomposites. The results show that the graphene-Ag2Se nanocomposites can be prepared by a simple hydrothermal method, and Ag2Se particles are well distributed on the graphene nanosheets.