Hierarchically structured europium tungstate integrated with a carbon nanofiber nanocomposite for enhanced electrochemical detection of antioxidants in various foods

Abstract

As a water-soluble derivative of vitamin E, trolox, a potent antioxidant, is extensively utilized in food and pharmaceutical products. Owing to its vital role in scavenging free radicals, maintaining optimal levels in consumables is crucial. Careful monitoring of its concentration ensures effective antioxidant activity, preserves nutritional quality, and prevents excessive intake that may disrupt the body's redox balance. Europium tungstate (Eu₂WO₆, EWO) has recently emerged as a promising electrocatalytic material owing to its unique redox-active lattice and high structural stability, which facilitates rapid electron transfer in electrochemical sensors. In this work, EWO nanoparticles were synthesized using the hydrothermal method and subsequently integrated with carbon nanofibers (CNFs) to form a nanocomposite, to enhancing conductivity, surface area, and mechanical stability. The hybrid EWO–CNF material exhibited uniform nanoparticle decoration on the fibrous network, as confirmed by XRD, FTIR, XPS, SEM, and HRTEM analyses, and demonstrated strong interfacial interactions that promote electron transport and active site accessibility. The EWO–CNF-modified electrode was employed for sensitive Trolox detection using linear sweep voltammetry (LSV). The sensor showed a wide linear range (0.1–1949 μM), a low limit of detection (0.027 μM), and high sensitivity (4.125 μA μM⁻¹ cm⁻²). The modified electrode exhibited excellent reproducibility across multiple electrodes and retained over 90% of its initial response after four weeks, highlighting long-term stability. Practical applicability was demonstrated via analysis in almond and tomato extracts, where the sensor accurately quantified spiked Trolox concentrations with satisfactory recoveries. These results indicate that the EWO–CNF nanocomposite is a robust, high-performance material for rapid and reliable electrochemical antioxidant sensing in real samples.