Synthesis and characterization of copper nanoparticles using Allium cepa (L.) outer peel at ambient temperature

Nanotechnology is increasingly finding applications in various fields like material engineering, medicine, and environmental science. Due to their antimicrobial, catalytic, and electrical properties, copper nanoparticles (CuNPs) have been used in biomedical treatments, cleaning up the environment, and making electronic devices. However, toxic chemicals and high energy consumption are the challenges of conventional synthesis methods of nanoparticles. This study explores the eco-friendly synthesis of copper nanoparticles (CuNPs) using the outer peel extract of Allium cepa L. at ambient temperature (25 ± 2°C). The phytochemicals in the extract were used as reducing agents in the process. The formation of CuNPs was confirmed by a color change to dark brown when they encountered Cu2+ ions. Using UV–Visible spectroscopy to characterize the sample showed broad absorbance band around 380-600 nm, which means nanoparticles are forming. Using Fourier Transform Infrared (FTIR) analysis, functional groups like hydroxyl (O-H), Cu-H, and C-C were found to be reducing Cu ions. X-Ray Diffractometry (XRD) confirmed the crystalline structure of the CuNPs, while Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) showed pseudo-spherical, rod-like, and polygonal particles with diameters ranging from 8.31 to 179.75 nm. Energy Dispersive X-Ray Spectroscopy (EDS) analysis indicated the presence of copper, oxygen, and sulfur. The results indicate a sustainable alternative for advanced nanotechnology synthesis and applications by demonstrating an efficient, cost-effective, and environmentally friendly approach to synthesizing CuNPs under ambient conditions.