Advanced TiO2-ZnO/graphene hybrid nanocomposite for ultra-sensitive electrochemical detection of fipronil pesticide

Abstract

The increasing use of fipronil, a phenylpyrazole insecticide with known toxicity and endocrine-disrupting effects, poses significant environmental and health risks due to its persistence in agricultural products and ecosystems. This study presents the development of a novel TiO₂-ZnO/graphene (GTZ) hybrid nanocomposite electrode for ultra-sensitive electrochemical detection of fipronil. The GTZ nanocomposite was synthesized using a microwave-assisted technique and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). SEM results showed that TiO₂ and ZnO nanoparticles were well dispersed in the graphene layer. XRD diffractograms confirmed the presence of the anatase TiO₂ phase and Wurtzite ZnO phase in GTZ nanocomposites. FTIR analysis revealed the presence of oxygen-containing functional groups, Ti-O and Zn-O bonds, indicating successful modification of graphene. Cyclic voltammetry was employed to evaluate the sensing capabilities of the GTZ electrode, demonstrating a linear response to fipronil concentrations as low as 0.0023 µg/L, with a high reproducibility (RSD 1.77 %). The electrode’s enhanced sensitivity can be attributed to the synergistic interaction between TiO₂-ZnO nanoparticles and graphene, providing a large electroactive surface area and improved electron transfer kinetics. This study confirms the potential of GTZ nanocomposite electrodes as a cost-effective and portable platform for real-time monitoring of fipronil residues in environmental and agricultural samples.