LAUSR

Abstract A 3D NiCo2S4 nanowire arrays directly grown on Ni foam electrode (NiCo2S4/NF) is prepared by two-step simple hydrothermal process. The morphology and phase composition of NiCo2S4/NF are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). As expected, in the following electrocatalytic measurement, the binder-free, self-made NiCo2S4/NF electrode exhibits much higher catalytic activity, lower onset potential, better stability and greater tolerance towards urea electrooxidation compared with the Ni3S2/NF electrode synthesized under the same reaction conditions. The NiCo2S4/NF electrode delivers a current density of 720 mA cm−2 at 0.18 V (vs. Ag/AgCl) in a solution containing 5 mol L−1 KOH and 0.33 mol L−1 urea. The impressive electrocatalytic activity of the NiCo2S4/NF catalyst is largely ascribed to its distinctive structure, which exposes more electrochemical active sites at the electrode–electrolyte interface. Besides, the high intrinsic electronic conductivity also largely boosts the charge transfer rates for urea electrooxidation. The results demonstrate that the NiCo2S4/NF electrode showing a beneficial application prospect in the wastewater treatment and direct urea fuel cells.