NiCo2O4 hexagonal nanoplates anchored on reduced graphene oxide sheets with enhanced electrocatalytic activity and stability for methanol and water oxidation

We have synthesized highly active NiCo2O4-reduced graphene oxide (NiCo2O4- rGO) hybrid material as non-precious bi-functional electrocatalyst for effective oxidation of methanol and water. The hexagonal nanoplates of NiCo2O4 are grown on rGO sheets by two-step solution phase method. The physiochemical properties of NiCo2O4-rGO hybrid composite have been evaluated by powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and nitrogen sorption measurements. The electrocatalytic activity for methanol and water oxidation on NiCo2O4-rGO, NiCo2O4 and rGO electrodes is tested under alkaline conditions. Results show that the NiCo2O4-rGO hybrid shows higher methanol oxidation peak current density of 16.6 mA cm(-2) and lower onset potential (similar to 256 mV) in methanol oxidation. Likewise, in water oxidation it shows earlier onset overpotential (similar to 300 mV) and high current density (similar to 75 mA cm(-2)) as well as smaller overpotential of similar to 390 mV is required to reach a current density of 10 mA cm(-2). In addition, the hybrid NiCo2O4-rGO electrode shows excellent catalytic stability in both methanol and water oxidation reactions. The improved electrocatalytic activity of NiCo2O4-rGO is attributed to resilient synergistic effects between NiCo2O4 and rGO sheets. (C) 2016 Elsevier Ltd. All rights reserved.