The XRD patterns of as-synthesized and calcined CuO nanoparticles using different precursors are
shown in Figure 1. XRD peaks confirm that the formation of CuO from each precursor was in monoclinic
phase. The characteristic peaks located at 2 = 32.58°, 35.47°, 38.97° and 48. 74° are assigned to (110),
(002), (200) and ( 202) plane orientation of CuO (JCPDS 80-1268). For Cu(NO3)2 material, the basic
crystals with 4 main peaks of CuO in as-synthesized sample were obviously occurred. After calcination,
the increase of intensity peak was obtained and XRD pattern is still identical to as-prepared precipitate
pattern. This result indicates that the crystallinity of CuO was enhanced by sufficient nucleation energy
from thermal treatment. For CuCl2 material, the basic crystal of as-synthesized CuO was indistinctly
appeared but the presence of CuO peaks was stronger occurred after calcinations process. XRD results
suggest that the formation of CuO can be obtained by co-precipitation method. Good crystallinity of CuO
is received by Cu(NO3)2, comparing to CuCl2 precursor and the increase of crystallinity and its size can
be effectively achieved after annealing treatment.