First Principles’ Insight Into Electrochemical Sensing for Persistent Organic Pollutants: A Case Study on Organochlorines and Organophosphates Using C₄N₃-Based Nanosensors

Detecting persistent organic pollutants (POPs), particularly hazardous pesticide classes such as organochlorines and organophosphates, is crucial due to their long-term persistence, global distribution, and serious ecological and health impacts. This study evaluates the capability of C4N3 as a sensitive and selective detecting nanomaterial for the sensing of POPs, utilizing density functional theory (DFT). For this purpose, the adsorption characteristics of dichlorodiphenyltrichloroethane (DDT), fenthion (FH), fenitrothion (FTN), methoxychlor (MXC), and ronnel (RO) were calculated to comprehend the influence of these pesticides on the electronic properties of C4N3. The observed trend of adsorption energy exhibited by complex molecules is FH@C4N3> FTN@C4N3> DDT@C4N3> RO@C4N3> MXC@C4N3. The adsorption energies revealed the weak van der Waals interactions and were further supported by the results of quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) analysis. Mild bonding interactions between the C4N3 surface and DDT, FH, FTN, MXC, and RO analytes can lead to better selectivity. Using the natural bond orbital analysis, molecular electrostatic potential, electron-localization function, density of state calculations, and charge-decomposition analysis, the electronic characteristics of the complexes, DDT@C4N3, FH@C4N3, FTN@C4N3, MXC@C4N3, and RO@C4N3, were evaluated to ascertain the notable effects of adsorbing these analytes on the C4N3. NBO analysis showed charge migration from the C4N3 to the pollutants in the POP@C4N3 complexes. Transition-state (TS) theory was employed to estimate the recovery period at 300 K in order to estimate the reusability of the C4N3. These findings provide a theoretical foundation for possibly using the C4N3 as a sensing material intended to detect significant POPs, such as dichlorodiphenyltrichloroethane, FH, FTN, MXC, and RO in the environment.