Direct growth of NiCo2O4 nanostructures on conductive substrates with enhanced electrocatalytic activity and stability for methanol oxidation

Abstract

In this report, NiCo₂O₄ nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo₂O₄ on stainless steel (SS) had a high surface area (119 m² g⁻¹) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo₂O₄ showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co₃O₄ synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity, large surface area of NiCo₂O₄ and the fast ion/electron transport in the electrode and at the electrolyte–electrode interface. This is important for further development of high performance non-platinum electrocatalysts for application in direct methanol fuel cells.