Nano-size cobalt-doped cerium oxide particles embedded into graphitic carbon nitride for enhanced electrochemical sensing of insecticide fenitrothion in environmental samples: An experimental study with the theoretical elucidation of redox events

• Published in: The Science of the total environment 2024-01, Vol.909, p.168483-168483, Article 168483
• Main Authors: Đurđić, Slađana, Vlahović, Filip, Ognjanović, Miloš, Gemeiner, Pavol, Sarakhman, Olha, Stanković, Vesna, Mutić, Jelena, Stanković, Dalibor, Švorc, Ľubomír
• Format: Article
• Language: English
• Subjects: apples; carbon nitride; ceric oxide; Cobalt-doped cerium oxide; Density functional theory; detection limit; Electrochemical detection; electrochemistry; environment; Environmental; Fenitrothion; graphene; Graphitic carbon nitride; nanocomposites; nanoparticles; oxidation; sensors (equipment); tap water; voltammetry
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.168483

In the present work, a nanocomposite, based on embedding Co-doped CeO2 nanoparticles into graphitic carbon nitride (g-C3N4), was applied to functionalize commercial glassy carbon paste. This is the first application of the electrochemical sensor, developed through the proposed procedure, in electrochemical sensing. The sensor was utilized for the electrochemical determination of organophosphate pesticide fenitrothion (FNT). Cyclic voltammetry identified reversible oxidation of FNT (oxidation at 0.18 V and reduction at 0.13 V) and additional reduction at −0.62 V vs. Ag/AgCl in HCl solution (pH = 1). Theoretical calculations were carried out to model and elucidate experimentally observed redox processes. Special attention was devoted to modeling experimental conditions, and based on the obtained results, a detailed redox mechanism of the investigated analyte was proposed. This represents the first complete and unambiguous elucidation of the FNT redox mechanism, supported by joined experimental and theoretical data. Square wave voltammetry (SWV) was utilized for quantification, whereby the FNT oxidation peak was chosen for monitoring the analyte concentration. The developed sensor provided a nanomolar detection limit (3.2 nmol L−1), a wide linear concentration range (from 0.01 to 13.7 μmol L−1), and good precision, repeatability, and selectivity towards FNT. Practical application possibility was explored by testing the sensor performance for examining tap water and apple samples. Recovery tests, conducted during the FNT-spiked sample assays, showed a great application capability of the developed sensor for real-time monitoring of FNT traces in environmental samples. [Display omitted] •A novel composite for detecting insecticide fenitrothion (FNT) was proposed.•The sensor was based on Co-doped CeO2 particles embedded into a g-C3N4 composite.•The redox process of FNT, occurring at the electrode surfaces, is clarified by DFT.•The sensor demonstrated wide linearity and high sensitivity with a LOD of 3.2 nmol L−1.•The practical applicability of the sensor was tested in environmental samples.