Monodisperse nickel nanoparticles supported on multi-walls carbon nanotubes as an effective catalyst for the electro-oxidation of urea

Monodisperse nickel nanoparticles (NPs) were synthesized by reduction of nickel acetylacetonate with oleylamine in 1-octadecene, and uniformly dispersed on multi-walls carbon nanotubes via sonication. The electro-oxidation activity and stability of the catalyst were investigated by cyclic voltammetry and chronoamperometry respectively. Characterization results indicate that the 80%Ni/MWCNT (80% represent the wt% of Ni) catalyst shows the highest electro-oxidation activity (1866 mA cm⁻² mg⁻¹) and stability for urea electro-oxidation, which is higher than most reported Ni-based catalysts. In addition, the urea electro-oxidation process is a mixed control of diffusion and kinetic limitation, as demonstrated by the effects of scan rate on the peak current density and peak potential. Subsequently, the impact of diffusion for the different catalysts varies with the change of Ni loading, which is verified by experiments.