Nickel nanoparticles-decorated graphene as highly effective and stable electrocatalyst for urea electrooxidation

Among the various carbonaceous materials, graphene is highly considered to provide the optimum support for the electrocatalytic materials due to its excellent electrical conductivity and extremely large surface area. In literature, based on our best knowledge, few studies have been reported to introduce effective electrocatalysts for urea oxidation. In this study, Ni-decorated graphene sheets are introduced as effective and stable electrocatalyst for urea oxidation. The introduced composite was prepared by reflux of graphene oxide with nickel acetate at 120 °C for 10 h followed by calcination in argon atmosphere at 850 °C for 2 h. X-ray diffractometer (XRD), transmission electron microscope (TEM) and Raman spectroscopy techniques confirmed formation of graphene sheets decorated by nickel nanoparticles. The synthesized Ni-decorate graphene shows distinct electrocatalytic activity toward urea oxidation. Numerically, using 2 M urea solution (in 1 M KOH) the corresponding current density was 150 mAcm-2 (2100 mAcm-2 g-1) with clear urea oxidation peaks in the forward and reverse scans. Study the influence of metal loading indicated that the amount of nickel nanoparticles should be optimized as the best performance has been observed when equal amounts of nickel acetate and graphene oxides were utilized during the preparation process. The introduced decorated graphene reveals good stability at various applied voltages. Overall, the study emphasizes the advantage of using graphene as support to distinctly enhancing urea electrooxidation.