Simple hydrothermal synthesis of mesoporous spinel NiCo2O4 nanoparticles and their catalytic behavior in CH3OH electro-oxidation and H2O2 electro-reduction

Abstract

Mesoporous spinel NiCo₂O₄ nanoparticles were synthesized via a simple hydrothermal strategy. Their physicochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectra (SEM-EDS), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperomerty (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo₂O₄ materials exhibit a particle size of about 200 nm, a specific surface area (SSA) of 88.94 m² g⁻¹ and a mesopore volume of 0.195 cm³ g⁻¹. The binary electroactive sites of Co and Ni species, high electron conductivity and intriguing mesoporous structures of the NiCo₂O₄ electrode favor its desirable electro-catalytic activity. A current density of 93 mA cm⁻² at 0.6 V in 1 M KOH and 0.5 M CH₃OH electrolytes was obtained for CH₃OH electro-oxidation, and a current density of 130 mA cm⁻² at −0.3 V in 3 M NaOH and 0.5 M H₂O₂ electrolytes was achieved for H₂O₂ electro-reduction. Moreover, the NiCo₂O₄ electrode exhibits a high stability for both catalytic reactions, showing the potential for further development of high performance non-Pt catalysts based alkaline fuel cells (AFCs).