Enhanced electrocatalytic activity of NiO nanoparticles supported on graphite planes towards urea electro-oxidation in NaOH solution

摘要

Nickel oxide nanoparticles are fabricated onto graphite planes [NiO/Gt] by chemical precipitation of Ni(OH)(2) particles with consecutive calcination at 400 degrees C. The formed electrocatalysts are characterized using X-ray diffraction (XRD) and Transmission electron microscopy (TEM). TEM images demonstrate the deposition of NiO nanoparticles on graphite surface through their crystallite lattice fringes with spacing values of 2.45 angstrom (111), 2.10 angstrom (200) and 1.48 angstrom (220). The electrocatalytic activity of NiO/Gt electrocatalyst is examined towards urea electro-oxidation in NaOH solution using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Urea oxidation peak current density is observed at NiO/Gt electrocatalyst containing 15 wt% NiO [NiO/Gt-15] at a potential value of +640 mV (Ag/AgC1) with a current density value of 17.63 mA cm(-2). The loading amount of NiO in the prepared electrocatalyst significantly affects its electrocatalytic performance. NiO/Gt-15 exhibits the highest urea oxidation current density with the desired stability. The lower Tafel slope, charge transfer resistance and the higher exchange current density and diffusion coefficient values of urea molecules at NiO/Gt-15 surface elect its application as a promising electrocatalyst material during urea oxidation reaction in fuel cells. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.