Copper nanoparticles (CuNPs) have received significant attention due to their unique physical and chemical properties, and low preparation cost. These nanoparticles have a wide range of applications such as heat transfer systems, antimicrobial agents, super strong sensors, and catalysts. In this research, CuNPs were synthesized using a green synthesis method with three different plant extracts; oak leaves, eremurus and sparrow tongue leaves. The green synthesis method is an eco-friendly approach that uses natural resources to produce nanoparticles, avoiding the use of toxic chemicals. The use of plant extracts as reducing and stabilizing agents in the synthesis of CuNPs has been shown to be an effective and sustainable approach. The results of this study demonstrated that the type of used plant extract can have a significant impact on the properties of the synthesized CuNPs. The XRD analysis showed that all three samples contained Cu phases in different proportions and sizes. The sample synthesized using oak leaf extract had the largest crystallite size of CuNPs (23.37 nm), followed by the sample synthesized using Eremurus tree extract (22.35 nm), and then by the sample synthesized using sparrow tongue extract (16.61 nm). The FESEM images showed that the sample synthesized with oak extract had the largest and most uniform particles, while the sample synthesized with sparrow tongue extract had the smallest and nearly homogeneous particles. The UV-Vis spectroscopy showed that all three samples had a prominent absorption peak at approximately 575 nm, attributed to the surface plasmon resonance of copper nanoparticles. The FT-IR analysis revealed the presence of different functional groups in each sample, indicating that the plant extracts have different effects on the reduction and stabilization of Cu NPs. The peaks at position of 541 cm-1, 543 cm-1 and 540 cm-1 are commonly associated with copper-oxygen (Cu-O) stretching vibrations of oak leaf, Eremurus tree and sparrow tongue extract, indicating the presence of copper oxide or other copper-oxygen bonds. The antibacterial and antifungal properties analysis showed that the CuNPs produced using oak extract have the most potent antibacterial and antifungal efficacy among all three microorganisms investigated.
