Fabrication of nickel oxide decorated CNTs/GO nanohybrid: A multifunctional electrocatalyst for overall electrochemical water splitting

Hydrogen production from water as renewable energy resource is vital to fulfil the huge energy demands without any hazardous environmental impact. Pursuing the efficient, durable and economical electrocatalyst other than benchmark expensive materials such as Pt, Ru, and Ir, for water electrolysis is a big challenge to produce the hydrogen as clean fuels. Here, we have successfully decorated nickel oxides nanoparticles over the carbon nanotubes covered by the graphene oxide layers (GO/NiO@CNTs/GO) using a facile hydrothermal method and utilized as electrocatalyst for electrochemical water splitting. The surface morphology and structure was assessed using a variety of analytical techniques, including scanning electron microscopy (SEM), energy dispersive X-rays spectroscopy (EDX) and X-ray diffraction (XRD). As prepared nanohybrid (GO/NiO@CNTs/GO) was utilized as multifunctional electrocatalyst to investigate the water electrolysis potential via different electrochemical techniques including linear sweep voltammetry (LSV), and cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. The fabricated electrode exhibited a lower overpotential of 236 mV and 208 mV at the standard current density of 10 mAcm⁻² under alkaline and acidic conditions, respectively. Enhanced double layer capacitance (C_dl) and reduced charge transfer resistance (R_ct) also showed the boosted performance for the hybrid materials with long term stability. The carbon based nanohybrid (GO/NiO@CNTs/GO) showed the promising potential having multifunctional characteristics including oxygen and hydrogen evolution reactions along with overall electrochemical water splitting.