Improved electrochemical performance of nickel-cobalt hydroxides by electrodeposition of interlayered reduced graphene oxide

Efficient, economical, and eco-friendly water splitting catalysts are in priority to replace the fossil fuels. In the presented work, reduced graphene oxide is formed through electrochemical reduction and applied as an effective interlayer between nickel foam substrate and nickel-cobalt hydroxide catalyst to augment its activity toward hydrogen evolution reaction. Through subsequent cyclic voltammetry deposition of nickel-cobalt hydroxide over the surface of supported interlayer, the prepared electrocatalyst exhibited remarkable performance by reaching a current density of 10 mA cm(-2) at a small overpotential of 60 mV in 1.0 M KOH electrolyte, much lower than that of the same electrocatalyst without interlayer (78 mV). The proposed strategy made the active metallic catalyst phase acquiring a small Tafel slope and superior durability for hydrogen production in alkaline medium. By utilizing the reduce graphene oxide interlayer, the electrical conductivity of the final nickel-cobalt hydroxide electrode was boosted. Furthermore, a clear transition from ordered reticulated arrays of nanosheets to roughened and disordered nanosheet-comprised nanospheres is demonstrated for surface morphology of nickel-cobalt electrocatalyst that indeed prompts the increase in its electrochemically active surface area. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.