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

Abstract

Ni-Cu alloy nanoparticles loaded onto ZnO- coated multi-walled carbon nanotubes (MWCNTs) were evaluated as anode catalysts in direct urea fuel cells. The Ni-Cu/ZnO@MWCNT catalyst was synthesized by a two-step hydrothermal process. Uniform distribution of the spherical Ni-Cu alloy nanoparticles on the ZnO@MWCNT surface was realized, as ascertained by scanning electron microscope and transmission electron microscope. A Ni-Cu/MWCNT catalyst was also prepared and evaluated to examine the effect of the ZnO coating on the electrocatalytic activity of Ni-Cu/ZnO@MWCNT. Cyclic voltammetry of the Ni-Cu/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/0.07M urea. The Ni-Cu/ZnO@MWCNT catalyst exhibited superior catalytic activity for urea electro-oxidation than Ni-Cu/MWCNT, owing to the electronic interaction between its different components, viz, Ni, Cu, and ZnO@MWCNT. A unit cell based on the Ni-Cu/ZnO@MWCNT anode exhibited peak power densities of 26.9 and 44.36 mW cm(-2) at 20 and 50 degrees C, respectively, in 3 M KOH/0.70M urea fuel. (c) 2017 Elsevier Ltd. All rights reserved.