Charge storage characteristics of layer-by-layer assembled nickel hydroxide and graphene oxide nanosheets

Abstract

In this study, layer-by-layer assembled thin films composed of nickel hydroxide and graphene oxide nanosheets were produced via simple dip coating process. The surface topography of the thin films was investigated by atomic force microscopy measurements. Electrical conductivity of the thin films was enhanced by chemical reduction with hydrazine vapor. The effect of chemical reduction on the surface chemical structure was analyzed by X-ray photoelectron spectroscopy. To utilize the produced thin films as possible electrodes for electrochemical energy storage devices, cyclic voltammetric measurements were performed. The areal capacitance of a reduced 9-bilayer [Ni(OH)(2)/graphene oxide] thin film reached 5.2mFcm(-2) at a scan rate of 2mVs(-1), outperforming similar layer-by-layer assembled metal hydroxide/graphene thin films. Lastly, charge storage characteristics of as-deposited and reduced films were investigated by performing cyclic voltammetry at different scan rates and electrochemical impedance spectroscopy.