Green synthesis of copper oxide via onion (Allium cepa) peel extract and evaluation of its antioxidant activity

Abstract

Aim: The present work aimed to synthesize copper oxide (CuO) nanoparticles through green approach using waste
onion (Allium cepa) peel extract and to evaluate the CuO antioxidant properties. Materials and Methods: In this
study, onion peel extract was used as a natural reducing agent for the reduction of copper sulfate. While antioxidant
activity of synthesized compound was evaluated using ABTS and DPPH assay. Results: Fourier transform
infrared spectroscopy (FTIR) spectroscopy, zeta potential analysis, and XRD analysis were used to characterize
the synthesized CuO. The FTIR measurements confirmed presence of plant moieties on CuO particles. From
X-ray diffraction analysis data, we found that CuO particles were crystalline in nature with an average grain size
of 42.9 nm. The average zeta potential value of synthesised CuO particles was found to be −20 mV, this showed
that these particles were stable in nature. Percent antioxidant activity as per ABTS and DPPH assay was calculated
to be 55.55% and 33.6%, respectively. Conclusion: Results of this study showed that the CuO synthesized using
onion peel extract exhibited significant antioxidant activity.