Sustainable\nSynthesis of Rare Earth Metal Tungstates\n(REWO, RE = Ce, SM, Gd) for Electrochemical Detection of 4‑Nitrotoluene

In this study, the\nsynthesis and application of rare earth tungstates\nCe<sub>4</sub>W<sub>9</sub>O<sub>33</sub> (CeW), Sm<sub>2</sub>(WO<sub>4</sub>)<sub>3</sub> (SmW), and Gd<sub>2</sub>(WO<sub>4</sub>)<sub>3</sub> (GdW) for the electrochemical detection of 4-nitrotoluene\nwere investigated. The nanoparticles were synthesized using a deep\neutectic solvent (DES)-assisted solvothermal method, a technique known\nfor its precision and reproducibility. It resulted in materials with\nhigh thermal stability, excellent catalytic activity, and enhanced\nelectronic properties. The synthesized CeW, SmW, and GdW were employed\nto modify screen-printed carbon electrodes (SPCEs), a widely used\nand well-established method in the field, which were then characterized\nusing various techniques. Electrochemical performance was evaluated\nthrough cyclic voltammetry, differential pulse voltammetry, and amperometric\n(<i>i-t</i>) responses, all of which are standard methods\nin electrochemical analysis. The modified electrodes exhibited superior\nelectrochemical behavior compared to bare SPCEs, with CeW/SPCE showing\nthe highest reduction peak current for 4-nitrotoluene detection. The\nlinear range for detection was found to be for DPV= 0.01–576\nμM and for <i>i-t</i> = 0.001–306 μM,\nwith a limit of detection of DPV = 0.034 μM and <i>i-t</i> = 0.012 μM. The sensors demonstrated excellent selectivity,\nreproducibility, and stability, with minimal interference from other\nsubstances commonly found in environmental samples. Real-world applicability\nwas confirmed by testing the modified electrodes in the river and\ntap water samples spiked with 4-nitrotoluene. The CeW/SPCE sensor\nshowed rapid and sensitive response in both matrices, highlighting\nits potential for environmental monitoring. The robust performance\nof CeW, SmW, and GdW-modified electrodes underscores their suitability\nfor practical applications in detecting nitrophenols, contributing\nto effective environmental monitoring and pollution control. This\nresearch has the potential to inspire further advancements in the\nfield of electrochemical detection and environmental monitoring.