Electrochemical application of cobalt nanoparticles-polypyrrole composite modified electrode for the determination of phoxim

Molla Tefera; Merid Tessema; Shimelis Admassie; Meryck Ward; Lisebo Phelane; Emmanuel I Iwuoha; Priscilla G L Baker

doi:10.1016/j.acax.2021.100077

Electrochemical application of cobalt nanoparticles-polypyrrole composite modified electrode for the determination of phoxim

Anal Chim Acta X. 2021 Sep 21:9:100077. doi: 10.1016/j.acax.2021.100077. eCollection 2021 Nov.

Authors

Molla Tefera¹, Merid Tessema², Shimelis Admassie², Meryck Ward³, Lisebo Phelane³, Emmanuel I Iwuoha³, Priscilla G L Baker³

Affiliations

¹ Department of Chemistry, University of Gondar, P. O. Box 196, Gondar, Ethiopia.
² Department of Chemistry, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
³ Sensor Lab, Department of Chemistry, University of the Western Cape, Private Bag X17, Robert Sobukwe Drive, Bellville, 7535, South Africa.

Abstract

In this study, cobalt nanoparticles (CoNPs) were synthesized and cobalt nanoparticles modified glassy carbon electrode (CoNPs/GCE) was prepared by drop coating the nanoparticles on glassy carbon electrode. After preparing polypyrrole modified glassy carbon electrode (PPy/GCE) using electropolymerization of pyrrole in LiClO₄ solution, cobalt nanoparticles-polypyrrole composite modified glassy carbon electrode (CoNPs/PPy/GCE) was fabricated by drop coating the CoNPs on the PPy/GCE. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, FTIR spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry were used to study the morphological structure and electrochemical behavior of the sensors. The results demonstrated that PPy chains interacted with CoNPs through donor-acceptor bonds. Among all the electrodes, CoNPs/PPy/GCE exhibited highest electroactive surface area and lowest electron transfer resistance towards phoxim. Under the optimal conditions, the sensor showed linear relationship between the reduction peak current and the concentration of phoxim in the range of 0.025 μM-12 μM with the detection limit as 4.5 nM. Besides, the composite electrode demonstrated excellent reproducibility, good stability and selectivity towards the possible interfering substances. All of these properties made CoNPs/PPy/GCE a suitable electrochemical sensor for the electrochemical determination of phoxim in water samples using square wave voltammetry.

Keywords: Cobalt nanoparticles; Electrochemical sensor; Modified electrode; Phoxim; Polypyrrole; Water.