Electrocatalysis of Endosulfan Based on Fe(3)O(4): An Experimental and Computational Approach

[Image: see text] The present work reports the electrocatalytic oxidation of the organochlorine pesticide endosulfan (EDS) using iron oxide (Fe(3)O(4)) nanoparticles synthesized from Callistemon viminalis leaf extracts. As a sensor for EDS, Fe(3)O(4) 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/Fe(3)O(4) 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/Fe(3)O(4) 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.