Controlled Synthesis And Properties Of Nano-structured ZnO

The preparation technology of alumina templates with through-holesand Zn nanowire array prepared by direct current electrodeposition werestudied in this paper, as well the growth mechanism of Zn electrodepositedin the holes of template and thermal oxidation processes were discussed.The microstructure features of the Zn and ZnO nanowire arrays werecharacterized by FE-SEM, TEM, and XRD. The paper also studied theprocess of hydrothermal synthesis of ZnO nanostructured microspheres. Thecontrol agent type, concentration, hydrothermal temperature and calcinationtemperatures that influence the ZnO morphology and its luminescentproperties were characterized by SEM, PL, etc. The main results of thepaper are as follows:（1）The highly ordered porous alumina templates were prepared by theelectrochemical oxidation method, the hole widening process withoptimized way was carried out, by which the AAO template withthrough-holes were obtained conveniently. Zn nanowire arrays in templatehave been prepared by three-electrode system with DC electrodeposition.And effects of different electrolyte types and concentration on the sampleand thermal oxidation process of ZnO nanowire arrays were studied in detail.The results indicated that the high qulity through-hole AAO template has adiameter of100nm and the space between holes is about110nm,which wereachieved by etching in5wt%H3PO4solution with a holding time of30minand a temperature of40℃。the best conditions for Zn nanowire arraysdepositon were: ZnSO4of160g/L, potential of-1.1v，deposition time of30min; the best thermal oxidation process conditions is at a temperature of700℃and a holding time of10h.（2） ZnO Nanostructured microspheres were prepared byhydrothermal process, and the effects of control agent type PVP, PVA and PEG and their concentration on the morphnology of hydrothermalproducts,calcined product and its luminescent properties were studied bySEM,XRD,FT-IR and PL. Main research：(a)as PVP control agents，the PVPconcentration, hydrothermal temperature and calcinations temperature thatinfluence the sample morphology and its luminescent properties werestudied;(b)as PEG and PVA control agents，calcinations temperature thatinfluence the sample morphology and its luminescent properties werestudied. The results show that the hydrothermal condition affect themorphology of the product evidently, however, wurtzite of ZnO withdifferent morphology can be obtained by calcinating the hydrothermalproducts at600℃for1h. The PL analysis showed that the ZnO withdifferent morphology have different degrees of visible lighting in the400-600nm range. As PVP control agents，the structure unit of the product ischanged from nanoplates to the nanowire,and the lighting intensity ofcalcinated product of ZnO in the visible range improved with increasinghydrothermal temperatures. As PVA control agents, the lighting intensity ofcalcinated product in the visible range decrease with increasinghydrothermal temperatures. As PEG control agents, the lighting intensity ofcalcinated product has not any changes with the hydrothermal temperature.