Influences of the thickness of self-assembled graphene multilayer films on the supercapacitive performance

In this study, graphene multilayer films with controlled thicknesses deposited on indium tin oxide glass substrates were fabricated using electrostatic layer-by-layer self-assembly of negatively charged graphene oxide followed by hydrazine hydrate reduction. X-ray diffraction spectroscopy, Raman spectroscopy, UV–vis spectroscopy, field emission scanning electron microscopy and atomic force microscopy were used to characterize the microstructures and morphologies of the as-fabricated multilayer films. The supercapacitive properties of the multilayer film electrodes were investigated via cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrometry in a 0.5 M Na2SO4 electrolyte. The graphene multilayer films employed as the electrode materials not only exhibited nearly rectangular cyclic voltammetry curves at an exceedingly high scan rate of 2000 mV/s, but also exhibited highly linear and symmetrical charge/discharge curves, which indicated that they have ideal electric double-layer capacitive behavior. Furthermore, the supercapacitive performance of the as-prepared graphene multilayer films exhibited a strong dependence on the number of self-assembled layers. Moreover, the specific capacitance per surface area for each self-assembled graphene film exhibited almost no decay after 1500 cycles, implying excellent stability and reversibility. These electrochemical tests indicated that the as-prepared graphene films have great potential for supercapacitor applications.

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► Graphene multilayer films with controlled thicknesses were fabricated using electrostatic layer-by-layer self-assembly.
► The supercapacitive performance of the graphene multilayer films exhibited a strong dependence on the number of self-assembled layers.
► With increasing the number of self-assembled layers, the specific capacitance per surface area gradually increased.
► With increasing the number of self-assembled layers, the volume specific capacitance firstly decreased and then increased.