Electro-oxidation of pyrene on glassy carbon electrode modified with fMWCNTs/CuO nanocomposite

Abstract

The electrochemical oxidation of pyrene, a well-known polycyclic aromatic hydrocarbon, was investigated using a glassy carbon electrode (GCE) modified with nanocomposite of copper oxide nanoparticles incorporated functionalized multi-walled carbon nanotubes (fMWCNTs). The catalytic copper oxide nanoparticles (CuONPs) synthesized through a chemical co-precipitation method was combined with the highly electrically conductive functionalized multi-walled carbon nanotubes using a simple and efficient method. Several analytical techniques were employed in characterizing the nanomaterials namely: the scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and the ultraviolet–visible (UV–vis) spectroscopy, to validate the authenticity of the synthesis. The electrochemical behaviour of the proposed electrode was investigated in 10 mM [Fe(CN)6]3-/4- via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), revealing the highest current response and lowest charge transfer resistance at the hybrid nanocomposite modified electrode (GCE/fMWCNTs/CuO NPs) in comparison with the other electrodes studied in this work (GCE, GCE/CuO NPs, and GCE/fMWCNTs. The electrocatalytic efficacy of the electrodes towards pyrene oxidation was also evaluated, with a similarly outstanding increment in the oxidation peak current response and highly reduced resistance to charge transfer at the nanocomposite-modified glassy carbon electrode. This enhanced electrocatalytic activity facilitated the transport of electrons between the pyrene molecules and the nanocomposite-modified electrode which is attributable to the synergy between the functionalized multi-walled carbon nanotubes and the copper oxide nanoparticles. The low detection limit of 1.30 μM within the linear range (1.2–23.1 μM) demonstrated by the sensor indicates its high sensitivity and potential for environmental based analytical applications such as pyrene detection.