Electrocatalysis of Endosulfan Based on Fe3O4: An Experimental and Computational Approach

Gloria Uwaya; Njabulo Joyfull Gumede; Krishna Bisetty

doi:10.1021/acsomega.1c03995

Electrocatalysis of Endosulfan Based on Fe₃O₄: An Experimental and Computational Approach

ACS Omega. 2021 Nov 3;6(45):30515-30525. doi: 10.1021/acsomega.1c03995. eCollection 2021 Nov 16.

Authors

Gloria Uwaya¹, Njabulo Joyfull Gumede², Krishna Bisetty¹

Affiliations

¹ Department of Chemistry, Faculty of Applied Sciences, Durban University of Technology, P.O. Box 1334, Durban 4000 South Africa.
² Department of Chemistry, Mangosuthu University of Technology, P.O. Box 12363, Jacobs 4026, South Africa.

Abstract

The present work reports the electrocatalytic oxidation of the organochlorine pesticide endosulfan (EDS) using iron oxide (Fe₃O₄) nanoparticles synthesized from Callistemon viminalis leaf extracts. As a sensor for EDS, Fe₃O₄ was combined with functionalized multiwalled carbon nanotubes (f-MWCNTs) on a glassy carbon electrode (GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and the differential pulse voltammetry experiment were conducted to investigate the electrochemistry of EDS on the GCE/f-MWCNT/Fe₃O₄ sensor. Based on optimized experimental conditions, the reports of analytical parameters show a limit of detection of 3.3 μM and an effective sensitivity of 0.06464 μA/μM over a range of concentrations from 0.1 to 20 μM. With the proposed method, we were able to demonstrate recoveries between 94 and 110% for EDS determinations in vegetables. Further, a series of computational modeling studies were carried out to better understand the EDS surface adsorption phenomenon on the GCE/f-MWCNT/Fe₃O₄ sensor. The highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap (-5.18 eV) computed by density functional theory (DFT) supports the layer-by-layer electrode modification strategy's charge transfer and stability. Finally, transition state modeling was able to predict and confirm the mechanism of endosulfan oxidation.