Enhanced Electrocatalytic Oxidation of Urea at CuOx-NiOx Nanoparticle-Based Binary Catalyst Modified Polyaniline/GC Electrodes

Abstract

In this study glassy carbon (GC) electrodes modified with electropolymerized polyaniline (PANI) are functionalized by the electrodeposition of copper oxide (CuOx) and nickel oxide (NiOx) nanoparticles (NPs). The proposed binary modified GC electrodes are suggested as effective and stable electrocatalysts towards urea oxidation reaction (UOR). The proposed electrodes were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and mapping EDX. The electrochemical characterization, electrocatalytic activity, and catalyst’ durability of the as-prepared anodes were tested by linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). The loading of PANI and the catalyst’ deposition sequence were optimized. The modified electrode with PANI followed by electrodeposition of CuOx and NiOx showed higher electroactivity than without PANI, i.e., it increases by about four times for UOR simultaneously with a negative shift by 40 mV of the onset potential of UOR. Furthermore, the modified PANI fibers with electrodeposition of CuOx and NiOx, where CuOx is the top one, displayed the leading electrocatalytic stability and activity for UOR. The addressed electrode (NiOx/CuOx/PANI/GC) has a low cost, good selectivity and sensitivity, fast response, and high stability.