A novel Ni[sbnd]Cu/ZnO@MWCNT anode employed in urea fuel cell to attain superior performances

Abstract

NiCu alloy nanoparticles loaded onto ZnO coated multi-walled carbon nanotubes (MWCNTs) were evaluated as anode catalysts in direct urea fuel cells. The NiCu/ZnO@MWCNT catalyst was synthesized by a two-step hydrothermal process. Uniform distribution of the spherical NiCu alloy nanoparticles on the ZnO@MWCNT surface was realized, as ascertained by scanning electron microscope and transmission electron microscope. A NiCu/MWCNT catalyst was also prepared and evaluated to examine the effect of the ZnO coating on the electrocatalytic activity of NiCu/ZnO@MWCNT. Cyclic voltammetry of the NiCu/ZnO@MWCNT catalyst exhibited a peak current density of 30.02 mA cm−2 at 0.38 V (vs. Ag/AgCl) with a low onset potential in an aqueous solution of 0.4 M KOH/0.07 M urea. The NiCu/ZnO@MWCNT catalyst exhibited superior catalytic activity for urea electro-oxidation than NiCu/MWCNT, owing to the electronic interaction between its different components, viz, Ni, Cu, and ZnO@MWCNT. A unit cell based on the NiCu/ZnO@MWCNT anode exhibited peak power densities of 26.9 and 44.36 mW cm−2 at 20 and 50 °C, respectively, in 3 M KOH/0.70 M urea fuel.