Green Synthesis and Characterization of Crystalline CuO Nanoparticles using Aqueous Mentha Piperita L. Leaf Extract

Copper oxide nanoparticles are essential technology materials that are utilized as catalysts in the chemical industry, as well as in photonic and electronic devices and medical applications. Due to their applications in advanced technologies, we have concentrated on the production of CuO nanoparticles using enhanced, cost-effective, and environmentally friendly synthetic techniques. In this paper, we have presented a green synthesis technique to successfully synthesis copper oxide nanoparticles (CuO NPs) utilizing copper (II) sulfate pentahydrate (CuSO4.5H2O) as precursor salt and Mentha Piperita leaf extract as a reducing and stabilizing agent during the synthesis process. The precursor salt solution and reducing agent were mixed in a 1:1 volume ratio at 50 °C. The CuO NPs synthesized were confirmed by the characteristics Surface Plasmon Resonance (SPR) peak in the UV-visible region. Also, the optical direct band gap energy of the CuO NPs determined from the Tauc plot was 3.26 eV. The FTIR spectrum analysis confirmed existence of functional groups of polyphenols from Mentha piperita L. leaf extract, which are responsible for the reduction of Cu2+ ions and effective stabilization of CuO NPs. All the peaks observed in the XRD pattern revealed the production of CuO NPs having monoclinic structure with an average crystallite size of 42.51 nm. The surface morphology of the CuO nanoparticles was detected using SEM analysis. Further, the synthesis mechanism of CuO NPs has also been investigated.