Nickel Foam Supported-Co₃O₄ Nanowire Arrays for H₂O₂ Electroreduction

Ni foam supported-Co 3 O 4 nanowire arrays are prepared by a template-free growth method, followed by a thermal treatment in air, and are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric and differential thermal analysis. The Co 3 O 4 nanowires have a diameter of about 250 nm, a length up to 15 μm, and a Brunauer-Emmett-Teller surface area of 78.4 m 2 g −1 . They grow almost vertically from the surface of Ni foam skeleton, pack densely, and uniformly cover the entire surface of Ni foam skeleton. Electroreduction of H 2 O 2 on Co 3 O 4 nanowire arrays in alkaline medium is investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The Co 3 O 4 nanowire electrode exhibits superior activity, stability, and mass transport property for H 2 O 2 electroreduction. A current density of 90 mA cm −2 is achieved at −0.4 V in 0.4 mol dm −3 H 2 O 2 and 3.0 mol dm −3 NaOH at room temperature. The per gram current density measured at −0.4 V on Co 3 O 4 nanowires is about 1.5 times of that on Co 3 O 4 nanoparticles.