Green synthesis of Illicium verum-derived novel semiconducting Ag/Fe/Cu-trimetallic nanocomposites: A dual-functional platform for selective detection of pharmaceutical compounds and light-independent degradation of organic dyes

In the present work, phytochemicals derived from the extract of Illicium verum fruit have been used for the first time as capping, stabilizing and reducing agents to synthesize pH and thermally stable silver-, iron- and copper-based trimetallic nanocomposites (Ag/Fe/Cu-TNAs). Characterization was carried out by multiple spectroscopic and imaging techniques. Nanocomposites were found to be spherical in shape with an average size of 60 nm by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The presence of all three metals was evident from energy-dispersive X-ray spectroscopic analysis (EDS). X-ray diffraction (XRD) revealed a crystallite size of 17.83 nm. Shifts in the peaks of Fourier transform infrared (FTIR) spectra and the appearance of a broad peak between 250 and 400 nm in the UV-visible spectrum also provided convincing evidence for the formation of nanocomposites. An optical band gap of 3.8 eV indicated the semiconducting nature of the nanocomposites. This research represents the first demonstration of trimetallic nanocomposites as green and cost-effective nanosensors for the detection of an important pharmaceutical residue, levocetirizine. Levofloxacin was also detected effectively at a lower concentration. The limit of detection values for levofloxacin and levocetirizine were found to be 4.43 µM and 5.49 µM, respectively. The stoichiometric ratio and binding constant values for levofloxacin (2 : 3, 1.139 × 10⁴ M⁻¹) and levocetirizine (1 : 4, 1.153 × 10⁵ M⁻¹) revealed the strong interactions between the nanocomposites and the drug molecules, enabling them to serve as distinctive nanosensors in tap and well water. Furthermore, the nanocomposites were utilized to evaluate their catalytic potential against methyl orange dye by UV-visible spectroscopy in the absence of light. The findings revealed that the rate of degradation was substantially enhanced (93.48% in 2 h) in the presence of nanocomposites as compared to bare H₂O₂ (33% in 2 h). Our study explores the potential use of semiconducting Ag/Fe/Cu-TNAs as bio-sensors and catalysts for promising and viable applications, especially in wastewater treatment, a step forward to meet the 17 Sustainable Development Goals (SDGs).