Facile preparation of three-dimensional Ni(OH)2/Ni foam anode with low cost and its application in a direct urea fuel cell

Abstract

Three-dimensional Ni(OH)₂/Ni foam electrodes with low cost are simply fabricated via a template-free growth method and employed as efficient anodes for a direct urea–hydrogen peroxide fuel cell (DUPFC). The surface morphologies of Ni(OH)₂ catalysts on the electrodes can be easily controlled by altering the reaction temperatures. The nano-sheet (NS) Ni(OH)₂/Ni foam electrode exhibits highest catalytic activity towards urea electro-oxidation among the four electrodes. The oxidation current density of the NS Ni(OH)₂/Ni foam electrode reaches 337 mA cm⁻² at 0.45 V (vs. Ag/AgCl) with a low onset oxidation potential in 0.6 mol L⁻¹ urea and 5 mol L⁻¹ KOH solutions. The DUPFC using NS Ni(OH)₂/Ni foam anode shows an open circuit voltage of 0.86 V and high peak power density of 19.7 mW cm⁻² and 28.8 mW cm⁻² at 20 °C and 50 °C, respectively, which is much higher than the performance of direct urea fuel cells reported previously. The outstanding cell performance using a cheap NS Ni(OH)₂/Ni foam anode indicates DUPFC is a promising new type of fuel cell.