Porous NiCo2O4 nanostructures as bi-functional electrocatalysts for CH3OH oxidation reaction and H2O2 reduction reaction

Abstract Porous nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition route. Their physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate porous nanostructures with the specific surface area (SSA) and pore volume of 190.1 m2 g−1 and 1.136 cm3 g−1. Remarkably, the NiCo2O4 materials exhibit higher electrocatalytic activity, lower overpotential, better stability and greater tolerance compared to those of NiO and Co3O4 materials synthesized by the same procedure. As for the NiCo2O4 electrode, a current density of 98 mA cm−2 was obtained toward CH3OH electro-oxidation at 0.6 V in 1 M KOH and 0.5 M CH3OH electrolytes, and a current density of 223 mA cm−2 was achieved toward H2O2 electro-reduction at −0.3 V in 3 M NaOH and 0.5 M H2O2 electrolytes. Moreover, the NiCo2O4 electrode shows a desirable stability for both electrocatalytic reactions. The impressive electrocatalytic activity is largely attributable to the binary electroactive sites of Co and Ni species, intrinsic high electronic conductivity and superior porous nanostructures of the NiCo2O4 electrode, which are very promising for further development of high performance non-Pt catalysts alkaline fuel cells (AFCs).