To monitor particle size and chemical composition of the current green-synthesized CuO NPs, X-ray diffraction (XRD, Philips model: PW1730, λ = 1.54056 Å (Cu Kα irradiation), 2θ = 20–70°) was employed. For calculation of the crystallite sizes (D) of the samples Scherrer's equation were employed:3 (link) where, K is the shape factor constant (0.9), λ is the wavelength of the X-ray (0.1546 nm), β is the broadening of the diffraction line at half-maximum in radians, and θ is the Bragg's diffraction angle. Moreover, field emission scanning electron microscopy (FESEM, a TESCAN MIRA II, with the 20 kV voltage) and transmission electron microscopy (TEM, EM208S Philips microscope with accelerating voltage of 100 kv) were utilized for evaluating the surface topology and morphology of the green-synthesized CuO NPs. For depicting the particle size histogram, the size of more than 100 particles in the TEM image was estimated.