The Synthesis And Application Of Ultralong ZnO Nanostructures

In this paper,ultralong ZnO nanostructures with various morphologies have been synthesized by thermal evaporation.The photoluminescence and field emission properties of ZnO products are investigated,and we simply studied TiO₂ hollow spheres at last.This thesis contains the following works and innovations:1.Ultralong ZnO nanobrushes have been synthesized using a simple thermal evaporation and condensation method by Cu catalysts.The lengths of the ZnO nanobrushes range from several millimeters to more than one centimeter and the diameters of the branches' teeth are about 300 nm.The growth mechanism of the ultralong nanobrushes and the catalytic behavior of the copper are discussed.Room temperature photoluminescence spectra of the ultralong ZnO nanobrushes showed a UV emission band at about 388 nm and wide green emissions at around 525 nm,and we discussed the origin of green emissions.2.Ultralong ZnO hair-clasp-like nanostructure was synthesized on silicon substrate by the vapor-phase transport method at the temperature of 900℃under atmospheric pressure.The nanostructure and morphology of ZnO hair-clasps were evaluated by using X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The growth mechanism of the hair-clasps was investigated.Room temperature photoluminescence spectra of the hair-clasps showed a weak UV emission band centering at about 388 nm and wide green emissions around 525 nm. Field emission measurements demonstrated that the hair-clasps with many sharp tips of several nanometers in curvature radius possessed good performance with a turn-on field of～1.5 V/μm and a threshold field of～4.3 V/μm.3.We successfully synthesized ultralong ZnO nanocombs and nanobelts structures for the first time on copper substrate which are distinct from the reported ones.The novel structure and morphology of the as-synthesized ZnO nanocombs and nanobelts are characterized using X-ray diffraction and scanning electron microscopies.The yield of these nanoscopical structures is great and they have good repetitiveness,and we explained the growth mechanism for ZnO nanobelts.Other ultralong ZnO nanostructures were also successfully prepared via adjusting the experimental parameters.4.We have synthesized anatase-phase TiO₂ hollow spheres using potassium titanium oxalate(PTO) as the precursor.A bubble-template strategy is designed to construct the hollow nanostructure.The simple,general,clean,and convenient method presented here could generate desirable nanostructures,with high purity and good crystallizability.Thanks to the 3D architecture of the product,the photocatalytic performance has been significantly improved.We believe that the present work will open up to systematically explore ways to fabricate hollow nanostructures and thus find use in a variety of applications.