Design of ultrafine nickel oxide nanostructured material for enhanced electrocatalytic oxidation of urea: Physicochemical and electrochemical analyses

Abstract

Ultrafine nanostructured-NiO is designed via a simple electrodeposition process on a glassy carbon surface. The morphological and structural characteristics of the nickel oxide/glassy-carbon (NiO/GC) are investigated through field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The electrocatalytic performance of the designed material towards urea oxidation in 1.0 M KOH is studied under different conditions of deposition time, scan rate and urea concentration. Electrochemical characterizations of urea oxidation are accomplished using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). The electrodeposited ultrafine NiO displays a distinctive electrocatalytic urea oxidation performance. Numerically, the produced anodic current reached up to 1.089 mA for 0.25 M urea, with clear peaks for electrooxidation of urea in the forward and reverse sweep. EIS measurements showed that the diameter of semicircles is dependent on the experimental conditions, and the resistances of charge transfer values are found to be lower in the solutions containing urea, which is related to the excellent urea electrooxidation performance. Here, ultrafine nanostructured NiO is introduced to serve a critical function as a catalytic moderator to accelerate the charge transfer in the anodic part of the urea fuel-cell (UFC), which can affect both the efficiency and cost of UFCs.