Comparison between constant current electrochemical and pulse current approach in reduction of graphene oxide on nickel-nickel oxide foam

This study introduced a novel, nontoxic, scalable, two-step method for the fabrication of nickel-nickel oxide foam/electrochemically reduced graphene oxide (ERGO) electrodes. This procedure included drop cast and graphene oxide (GO) reduction by constant current and pulse current methods. The structure of achieved was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Electrochemical impedance spectroscopy (EIS) measurements are carried out to study the electrochemical behavior of ERGO/Ni-NiO foam electrodes. SEM images revealed that the wrinkling degree of the synthesized graphene layers increased in pulse current method. The Raman test results confirmed that the current density pulse method has more defects than the constant current. The XRD also showed that the interlayer spacing between the graphene sheets was higher in the pulsed current method. The ERGO/Ni-NiO foam fabricated by pulse current method provided the smallest ESR value, and thus the fastest charge/discharge process. The desirable electrochemical performance of ERGO/Ni-NiO foam electrode was mainly attributed to its irregular porous structure provided a large specific area, short ion diffusion distances and transport pathways for electrons. High-performance ERGO/Ni-NiO foam hybrid electrode materials made it as a reliable and accessible candidate for application in electrochemical energy storage.