Fabrication of efficient 4-methoxyphenol chemical sensor with ternary Mg/Cd/CeO 2 nanoparticles by linear sweep voltammetry for environmental monitoring

The use of the ternary metal oxide (TMO) nanoparticles (NPs) can be an effective approach to improve the physicochemical characteristics of nanocomposites (NCs) of interest for electroanalytical chemical sensing. In this study, a new type of electrochemical sensor was developed using magnesium/cadmium/cerium oxides (Mg/Cd/CeO₂ NCs) to detect 4-methoxyphenol (4-MP), an environmental contaminant. The Mg/Cd/CeO₂ NCs were synthesized via the solid-state chemical method and subsequently characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Brunauer-Emmett-teller (BET), and transmission electron microscopy (TEM), BET, and TEM. The electrochemical response and the sensor’s performance of the modified glassy carbon electrode (GCE) with 5% Nafion (conductive binder) were studied via cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The sensor showed a linear detection range (LDR) of 0.10-2.20 µM for 4-MP with a sensitivity of 1.978 µAµM⁻ 1 cm⁻ 2 , a limit of detection (LOD) of 0.034 µM, and a limit of quantification (LOQ) of 0.11 µM. The modified GCE (Mg/Cd/CeO₂ NCs/Nafion/GCE) showed better electrocatalytic performance and selectivity for 4-MP towards the interfering material and metal ions. The detection efficiency of the fabricated 4-MP chemical sensor was also optimized in a phosphate buffer solution (PBS) of different pH (5.7-7.5). The real-time application of the chemical sensor was validated by its successful analysis of 4-MP in spiked water samples through the standard-addition method. It was presented a comparison with other reported oxide-based electrochemical sensors in this report. For instance, compared with the GO@Co₃O₄/Y₂O₃ NCs/GCE sensor and the ZnO-CdO NCs/GCE sensor, the LOD of the proposed Mg/Cd/CeO₂ NCs/Nafion/GCE sensor was 40.8% and 68.8% lower, respectively. Furthermore, it also had a sensitivity about 30.2% higher than the ZnO-CdO NCs/GCE sensor. These relative values help clearly illustrate the enhanced analytical performance attained by the proposed sensor. In summary, this study describes a simple and robust approach towards the fabrication of a ternary Mg/Cd/CeO₂ NCs/Nafion/GCE-based chemical sensor system for the environmental monitoring of toxic phenolic pollutants.