“…For both W–ZnO and ZnO(ext) samples, strong diffraction peaks at 31.8° (100), 34.4°(002), 36.3°(101), 47.6°(102), 56.6°(110), 62.9°(103), 66.4°(200), 67.9°(112), and 69.1° (201) revealed the hexagonal structure of ZnO (JCPDS, 36–1451), and no other peaks related to impurities were observed. On the other hand, for ZnO/CuO NCs samples other than the hexagonal ZnO peaks, some additional diffraction peaks were observed at 2θ values of ≈35.6, 38.9, 48.9, 53.7, 58.4, 61.6, and 66.4°, which are associated with the (11–1), (111), (20–2), (020), (202), (11–3), and (31–1) crystalline planes of the monoclinic CuO (JCPDS, 48–1548), respectively . As observed from the diffractograms of NCs, with increasing concentrations of Cu (10–50%), the diffraction peak intensities of CuO gradually increase but conversely decrease in the peak intensities of ZnO.…”