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The electrode of Co3O4 nanowire arrays directly grown on nickel foam is prepared via a facile one-step method. The electrode is characterised by scanning and transmission electron microscopy and tested as the cathode of an Al–H2O2 semi-fuel cell. We found that Co3O4 forms clusters of nanowires with length up to around 15 μm and diameter around 250 nm. The nanowire is composed of interconnected nanoparticles. Effects of H2O2 concentrations, catholyte KOH concentration, catholyte flow rate and operation temperature on the cell performance are investigated. The cell exhibited an open circuit voltage of 1.4 V, and peak power densities of 85 and 137 mW cm–2 at 25 and 65 °C, respectively, while running on 0.4 mol L–1 H2O2 at a flow rate of 80 mL min–1.

Ni foam supported-Co3O4 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 Co3O4 nanowires have a diameter of about 250 nm, a length up to 15 μm, and a Brunauer-Emmett-Teller surface area of 78.4 m2 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 H2O2 on Co3O4 nanowire arrays in alkaline medium is investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The Co3O4 nanowire electrode exhibits superior activity, stability, and mass transport property for H2O2 electroreduction. A current density of 90 mA cm−2 is achieved at −0.4 V in 0.4 mol dm−3 H2O2 and 3.0 mol dm−3 NaOH at room temperature. The per gram current...