ZnO2/CNT Nanocomposite-Based Electrochemical Sensors for the Detection of Trinitrotoluene

Abstract

Global pollution of soil and water supplies due to the leftover dumping of nitroexplosives is a critical issue. Increasing mining and construction activity leads to a significant growth in the trinitrotoluene (TNT) market, making it a lethal contaminant that should be detected early to prevent consumption. Here, in this work, a highly sensitive voltammetric trinitrotoluene (TNT) sensor has been fabricated by modifying a gold electrode (AuE) with a ZnO₂/carbon nanotube (CNT) nanocomposite (ZnO₂/CNT@AuE). The ZnO₂/CNT nanocomposite was synthesized by the coprecipitation method. Morphological and chemical analyses of the synthesized nanostructure was done through different high-end characterization techniques [Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)]. The electrocatalytic reduction behavior of the electrochemical probe, ZnO₂/CNT@AuE, toward TNT was studied in phosphate buffer solution (PBS, pH 7.0) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The ZnO₂/CNT nanocomposite deposited on the electrode surface improves the conductivity and active sites for electrocatalytic reduction, significantly enhancing the designed sensor’s performance. The fabricated sensor exhibited an outstanding sensing performance and a rapid response when exposed to TNT with a higher sensitivity (80.53 μA cm^–2 μM^–1) and a lower detection limit (3.4 nM). In addition to the excellent efficacy, the newly developed sensor showed high reproducibility and long-term stability on repeated use. The sensor detects TNT over a wide linear range (4–500 nm) and has good anti-interference capabilities. The ZnO₂/CNT@AuE probe has been applied successfully to detect TNT in real water samples. Moreover, electrochemical applications can be expanded by implementing the present electrochemical strategy.