Structural and optical properties of CdO nanowires synthesized from Cd(OH)2 precursors by calcination

CdO nanowires were produced by calcination process using Cd(OH)2nanowires as precursors. The Cd(OH)2 nanowires were synthesized via arc discharge method submerged in de-ionized water. Transmission electron microscopy (TEM) analysis of the as-synthesized Cd(OH)2 nanowires revealed that nanowire morphology was abundant form with the diameters range from 5 to 40 nm. In addition to the nanowire morphology, Cd(OH)2 nanospheres and hexagonal shaped nanoparticles were also displayed. The Cd(OH)2 nanostructures were used as precursors to produce CdO nanowires and calcinated in air at 400 °C for four hours. After calcination, the structural, morphological and optical properties of the as-synthesized CdO nanowires were characterized by means of TEM, selected area electron diffraction (SAED), X-ray diffraction (XRD) and UV-vis spectroscopy. The XRD and SAED techniques showed that the as-synthesized Cd(OH)2 nanostructures could be transformed into CdO nanostructures after the calcination process. TEM results revealed that the as-synthesized CdO nanowires were 5-30 nm in diameter and shorter than corresponding Cd(OH)2 nanowires. In addition, the diameters of the spherical or irregular CdO nanoparticles ranged from 20 nm to 50 nm. UV-vis spectroscopy analysis was showed that the direct gap of the CdO nanowires were found to be 2.60 eV which is slightly higher than the earlier reported values of the bulk CdO for direct band gaps (2.3 eV) due to quantum size effect. (