Nickel-Cobalt Aerogel as a Highly Efficient Electrocatalyst for Dual Microfluidic Applications: Hydrogen Generation and Power Energy from Nitrogenous Compounds

Abstract

This research work presents a novel unsupported NiCo aerogel with high electrocatalytic activity, which was synthesized by an ultrafast method combining microwave heating and lyophilization. The novel aerogel was used as an electrocatalyst for the oxidation reactions of two different nitrogen compounds: urea and ammonium, with the aim of reducing the pollutant content in water and generating clean energy from the reduced hydrogen of oxidizing species. The NiCo aerogel was incorporated/evaluated in a microfluidic device in two ways: as an ammonium fuel cell and an alkaline urea electrolyzer, producing clean hydrogen in both systems. The unique physicochemical properties, particle size smaller than 0.1 nm, surface area of 52 m2 g-1, and the presence of NiCo metal alloys with the addition of species Ni-O, Ni-OH, and a higher percentage of Ni2+ enable the effective oxidation of species in the alkaline medium. Hydrogen production and power densities of up 3 × 10-4 μg s-1 and 0.74 mW cm-2, respectively, are observed. This work demonstrates for the first time an aerogel structure of non-noble metal (NiCo) used in two different microfluidic devices that oxidize nitrogenous compounds such as urea and ammonium and produce clean fuel as hydrogen.