Morales-Lozoya et al. suggest that the broader spectrum of the UV-vis band indicates greater polydispersity of the NPs. Fouda et al. report that the presence of a single SPR peak in the UV-vis spectrum at a wavelength between 300-400 nm provides an additional indication of the shape and size of the CuO NPs, indicating that they are spherical with small size since as their dimensions decrease to the nanoscale the wavelength of the light becomes large with the size of the NPs . Saif et al. reported a similar absorption peak around 383 nm, whereas Narayanan et al. observed a peak near 400 nm. Therefore, the results obtained confirm the successful formation of CuO NPs, in agreement with studies reported in the literature .