Potential application of reduced graphene oxide in electrocatalyst for hydrogen/oxygen evaluation reaction in water-splitting

The present study aims to develop a cost-effective bifunctional electrocatalyst having pronounced electrocatalytic activity at low activation energy barrier. Herein, we have synthesized reduced graphene oxide (rGO)based electrocatalyst materials meticulously structurally characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The electrochemical performance of catalyst has been examined by linear sweep voltammetry (LSV), Tafel slope, electrochemical impedance spectroscopy (EIS), and stability tests at different current densities in alkaline and acidic mediums. We demonstrate that the NiO-rGO composite exhibits excellent performance for hydrogen evaluation reaction (HER), attaining a current density of 10 mA/cm2 @ stable overpotential of 290 mV, while for the oxygen evaluation reaction (OER) performance for rGO was outstanding and attained a current density of 10 mA/cm2 @ overpotential of 272 mV. Furthermore, a prototype oxy-hydrogen (HHO) generator was designed using NiO-rGO and rGO as working electrodes in acidic and alkaline mediums, respectively, and platinum as a counter electrode. The Faraday efficiency of the designed generator is found to be 16 % and 11 % at 11 V cell potential in acidic and alkaline mediums, respectively. We envision this study paving the way for developing of efficient and cost-effective a portable hydrogen generator.