Copper and nickel-based oxides delicately tailored via galvanic reaction as electrocatalyst for solid-state direct urea fuel cell

Abstract

The sluggish kinetics of urea oxidation reaction (UOR) critically restrict the prevalence of direct urea fuel cell (DUFC), utilizing electrolyte containing urea/urine. In this work, the copper and nickel-based composite oxides are prepared by meticulously controlling the galvanic reaction of copper ion to metallic nickel and the high-temperature oxidation process. Based on a systematic electrochemical characterization of the catalyst, the as-fabricated nano-architectures are optimized toward UOR performance, showing a low potential of 1.39 V vs. RHE to drive 100 mA cm−2 in alkaline solution. The button-like DUFCs configuration of as-developed catalysts exhibits a maximum power density of 1.19 mW cm−2. Furthermore, the DUFCs assembled with bio-urine, including men, dogs, cats, and rats as electrolytes without further purification, show a similar voltage. These findings open up a direction to convert bio-waste into treasure.