NiO-Fe2O3 based graphene aerogel as urea electrooxidation catalyst

A NiO-Fe2O3 based graphene aerogel was employed as a novel catalyst material for the electrochemical oxidation of urea. The three-dimensional aerogels were synthesized by metal ions (Ni2+ and Fe3+)-induced self-assembly using poly(vinyl alcohol) (PVA) as the structural scaffold. The NiO-Fe2O3/rGO/PVA aerogels were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic performance of the aerogels for urea electrooxidation in an alkaline medium was investigated by cyclic voltammetry. The NiO-Fe2O3/rGO/PVA aerogel electrode exhibited significant reduction of the onset oxidation potential (∼90 mV) compared to that of NiO/rGO/PVA. The NiO-Fe2O3/rGO/PVA aerogel electrode showed a peak current density of 44.6 mA cm−2 at 0.33 M urea in 1.0 M KOH, which was 2.6-fold higher than that of NiO/rGO/PVA electrode. Moreover, the NiO-Fe2O3/rGO/PVA electrode showed only a 11% loss in the peak current after 200th cycles.