Ellagic, gallic, and tannic acids, along with other polyphenols and phenolic derivatives such as dihydroxybenzene, are often mentioned in the literature for their ability to form stable complexes with metal ions . The presence of hydroxyl groups in these plant polyphenolic compounds is fundamental for stabilizing these complexes with metal ions . All the peaks are sharp and strong, revealing the good crystallinity of the CuO nanostructures synthesized.