Cerium-doped iron oxide nanostructures used as a voltammetric sensor for the electrochemical detection of thymol in the presence of bentazone

Abstract

Cerium-doped Fe₂O₃ (Ce–Fe₂O₃) nanoparticles (NPs) were used to develop a modified electrochemical sensor based on a carbon paste electrode (CPE). In the present study, we used electrochemical techniques (CV, SWV and EIS) to illustrate the analytical behaviour and uses of CPE modified with Ce–Fe₂O₃ nanoparticles for the simultaneous determination of thymol (TML) and bentazone (BET). The synthesised Fe₂O₃ and Ce-doped Fe₂O₃ NPs were characterized using XRD, FTIR, FESEM with EDX, and TEM techniques. The average crystallite size of the synthesized nanoparticles was found to be 19 to 30 nm. The Ce–Fe₂O₃-modified carbon paste electrode (Ce–Fe₂O₃/CPE) exhibited superior electrochemical performance towards the oxidation of TML compared with Fe₂O₃/CPE. Ce–Fe₂O₃/CPE exhibited a linear response towards the detection of TML under investigational conditions, with a detection limit of 1.4052 × 10⁻⁸ mol L⁻¹. Various parameters such as heterogeneous rate constant (k°), number of electrons transferred (n), electroactive surface area of the electrode (A), and charge transfer resistance (R_ct) were calculated. The sensitivity, long-term stability and reproducibility of the developed sensor were estimated. The analytical validity of the developed electrode was examined through real sample analysis using soil samples.