Nickel foam supported mesoporous NiCo2O4 arrays with excellent methanol electro-oxidation performance

Abstract

In this study, nickel foam supported NiCo₂O₄ nanosheet and nanocloth arrays are directly prepared by a mild hydrothermal method and applied to methanol electro-oxidation. Several techniques, including powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy (EDS) and nitrogen absorption measurements, have been employed to characterize the physicochemical properties of the as-prepared catalysts. The electrocatalytic performances are investigated by cyclic voltammetry (CV), chronoamperometry (CA) measurements and electrochemical impedance spectroscopy (EIS). Impressively, NiCo₂O₄ nanosheet and nanocloth arrays both deliver excellent electrocatalytic performance for methanol electro-oxidation in an alkaline medium, including low onset potential (0.19 V, 0.16 V), high current densities (111 mA cm⁻², 134 mA cm⁻²) and a desirable electro-oxidation stability (90%, 88%). The excellent electrocatalytic performances of nickel foam supported NiCo₂O₄ nanosheet and nanocloth arrays originate from their unique 3D mesoporous architecture, which can provide adequate open spaces and shorter ion diffusion paths to facilitate rapid ionic transportation.