Template Infiltration Preparation Of Zinc Oxide Nano-tube Array

Zinc oxide colloid was prepared by sol-gel method using Zn(CH₃COO)₂·2H₂O and LiOH·H₂O as primary material and used it as starting building units to fabricate uniform ZnO nanotubes arrays by an infiltration technique in the nanochannels of anodic alumina membranes(AAO).The products were characterized by X-ray diffractometer(XRD), scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV -visible absorption spectra(UV-VIS) and X-ray energy dispersive spectroscopy(EDS). The effects of different preparation conditions such as reaction time,aging time and heat treatment temperatures on particle size and crystal were also studied by TEM and XRD. The choice which side of the anodic alumina membranes to infiltrate and dissolve, method of dissolution,dissolution time,heat treatment temperature and particle size were also studied.The surface morphology and chemical composition of the as-synthesized product were studied by SEM and EDS.It was found that reaction time should be less than 10 minutes,TEM image shows that the nanoparticles with the size range from 2 to 5 nm,it increased to 5 nm after aging 30d and 200 nm after heat treatment.XRD shows that ZnO nanoparticles have hexagonal wurtzite structure.SEM images show that the heat treatment temperatures should above 500℃to obtain nanotube.Heat treatment at 650℃the as-prepared ZnO are tubular textures with rough wall,which have outer diameters of 300 nm,and lengths of 5,urn or more,while at 700℃the nozzle can be saw clearly which have wall thickness of 50 nm and outer diameters of 300 nm.Nanotubes with outer diameters of 180-200 nm were also obtained using the nanoparticles which have aged for 30d.The formation mechanism of ZnO nanotubes was also discussed.ZnO nanoparticles are negatively charged;meanwhile,the pore walls of the AAO are positively charged.So the nanoparticles will adhere to the pore walls when passing the pore because of the electrostatic interaction and couple to tube after sintering for 3 h.There are gravitation and air flow simultaneously,the nanotubes will first form at the bottom of the pore and then extend to the top gradually.Because of the electrostatic repulsion between the nanoparticles there is a extreme value of the wall thickness at about 50 nm.