Electrophoretic deposition of graphene, carbon nanotubes and composite films using methyl violet dye as a dispersing agent

Cathodic electrophoretic deposition (EPD) of methyl violet (MV) was performed from aqueous solutions. The film microstructure and deposition mechanism were studied using scanning electron microscopy (SEM) and cyclic voltammetry (CV). MV allowed efficient dispersion of multiwalled carbon nanotubes (MWCNT) and graphene in aqueous suspensions. Thin films of MWCNT and graphene were obtained by cathodic EPD using MV as a charging, dispersing and film forming agent. The deposition yield was varied by variation of MV concentration in the suspensions and deposition voltage. The possibility to deposit both MWCNT and graphene using MV as a dispersing and charging agent allowed the fabrication of MWCNT–graphene composites by EPD. The film microstructures and advantages of cathodic EPD were discussed. The films were investigated for application in electrochemical supercapacitors (ES). Electrochemical investigation showed capacitive behavior of the films in 0.5 M Na2SO4 electrolyte. The specific capacitance (SC) of ∼130 F g−1 was obtained at a scan rate of 2 mV s−1, and the capacitance retention in the range of 2–100 mV s−1 was ∼50%. The impedance spectroscopy data were in agreement with simulation results, obtained using equivalent circuit model. The composite films showed improved capacitive behavior compared to the films of individual components.