Preparation of controlled ZnO nanostructures and their optical properties

ZnO nanostructures were synthesized via a facile temple-free chemical method. The effect of different zinc sources on the morphologies and properties of ZnO nanostructures has been investigated. FESEM, XRD, UV–Vis absorption spectra and PL spectra were used to characterize the as-synthesized ZnO nanostructures. It has been found that the distinct surface morphologies of ZnO nanostructures grown by using Zn(CH₃COO)₂·2H₂O, Zn(NO₃)₂·6H₂O, ZnSO₄·7H₂O and ZnCl₂ as ZnO zinc sources. The XRD patterns indicate that all the samples represent a hexagonal wurtzite structure and all diffraction peaks are indexed accordingly with the JCPDS card (No. 03-0888). The UV–Vis absorption spectra of them both exhibit a strong absorption in the ultraviolet region at band around at 400 nm. The band gaps of them are 3.17, 3.19, 3.20 and 3.27 eV, respectively. Being excited at 325 nm wavelength using a xenon lamp at room temperature, all the PL spectra consist of sharp emission in the UV range and abroad emission bands in the visible region ranging from 440 to 620 nm.