Facile synthesis of NiCo@rGO as bifunctional electrocatalyst for enhanced water splitting

Rapid depletion of fossil fuels and growth of greenhouse gases necessitates the shift toward renewable energy sources. Electrocatalytic water splitting in this regard has proven to be one of the best options for producing hydrogen gas as a fuel for generating electricity. Since the scarcity and high cost diminish the commercial use of noble metal catalysts, this study utilizes environmental friendly, stable, and cost-effective nickel cobalt over reduced graphene oxide electrocatalysts for efficient hydrogen evolution reaction and oxygen evolution reaction activities at low overpotential to give benchmark density of 10 mAcm2. Among the synthesized nanocomposites rGO-NiCo10% and rGO-NiCo15% showed enhanced oxygen evolution reaction activity producing a current density of 80 mAcm2 and 50 mAcm2 at overpotential 620 mV with low Tafel slopes 123.27 mVdec1 and 141.41 mVdec-1 respectively, comparing to activity of RuO2. Similarly, they produced a current density of 20.5 mAcm2 and 13.1 mAcm2 at overpotential 490 mV for hydrogen evolution reaction with low Tafel slope values 67.67 mVdec1 and 92.79 mVdec1. Electrochemical impedance spectroscopy analysis suggested feasible charge transfer kinetics at the catalyst-electrolyte interface with small Rct values channeling it to improve electrochemical performance.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.