Pulsed electrodeposition of reduced graphene oxide on Ni-NiO foam electrode for high-performance supercapacitor

Through electrodeposition, controlling hydrogen evolution reaction and selective electrochemical dealloying of copper from Ni-Cu porous foam, highly nanoporous nickel and nickel oxide is fabricated on the copper surface. Electrochemically reduced graphene oxide (ERGO) is loaded on the Ni-NiO foam as high-performance electrodes for supercapacitors through pulsed galvanostatic reduction of drop casted graphene oxide nanosheets at different duty cycles and frequencies. Surface morphology and composition of fabricated ERGO/Ni-NiO foam composite electrodes are characterized using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Raman Spectroscopy. Electrochemical impedance spectroscopy (EIS) measurements, galvanostatic charge/discharge (GCD) and cyclic voltammetry (CV) are carried out to study the electrochemical behavior of ERGO/Ni-NiO foam electrodes. From structural and electrochemical characterizations, optimized parameters for pulse duty cycle and frequency were found to be 10% and 1000 Hz, respectively. As a result, the ERGO/Ni-NiO foam film (i(c) = -10 mA/cm(2), f = 1000 Hz and DC = 10%) provides a specific capacitance of 2298 F/g in 1 M KOH at a current density of 1 A/g. Stability study of fabricated film represents a long cycling life up to 4000 cycles with 0.7% decay in specific capacitance at the high current density of 20 A/g in the potential range of 0-0.6 V vs. saturated calomel electrode (SCE). (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.