Ni–WC/C nanocluster catalysts for urea electrooxidation

Abstract

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.