Ni–WC/C nanocluster catalysts for urea electrooxidation

• The Ni–WC/C catalysts were prepared successfully by a simple impregnation method.
• The nickel particles were grown on the WC/C framework in clusters with nanoscale.
• Tungsten carbide promotes nickel to more active sites for urea electrooxidation.
• Ni–WC/C nanoclusters show superior catalytic activity for urea electrooxidation.

A nanocluster Ni–WC/C electrocatalyst is prepared through a sequential impregnation method and is used for the urea electrooxidation in alkaline conditions. The micro-morphology, lattice parameter, composition and surface states of Ni–WC/C particles are determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and X-ray photoelectron spectrometry (XPS) analysis. The electrooxidation activity and stability of the Ni–WC/C catalyst are also investigated by cyclic voltammograms and chronoamperograms. Characterization results indicate that the Ni nanoclusters are uniformly distributed on the WC/C framework, and the Ni–WC/C catalyst shows high electrocatalytic activity and stability for urea electrooxidation. The maximum current density at the Ni–WC/C electrode is almost 700 mA cm−2 mg−1 which is one order of magnitude higher than that at the Ni/C electrode, and the steady current density at the Ni–WC/C electrode is also markedly improved. Furthermore, the ESA values and XPS spectra indicate that the enhanced performance of the Ni–WC/C catalyst could be attributed to the structure effect and electron effect between nickel and tungsten carbide.

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