Mechanistic Investigations of PEG-Directed Assembly of One-Dimensional ZnO Nanostructures

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• 作者：Xingfu Zhou ; Dangyu Zhang ; Yan Zhu ; Yeqian Shen ; Xuefeng Guo ; Weiping Ding ; Yi Chen
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：December 28, 2006
• 年：2006
• 卷：110
• 期：51
• 页码：25734 - 25739
• 全文大小：718K
• 年卷期：v.110,no.51(December 28, 2006)
• ISSN：1520-5207

文摘

Mechanistic investigation on spherical assembly of the unique one-dimensional ZnO nanorods, solid nanocones,or hollow prisms with the closed -c end, directed by poly ethylene glycol (PEG) with different molecularweights, has been carried out using spectroscopic methods. The single crystalline ZnO nanoprisms, hollowalong the c axis but closed at the -c end, aggregate to urchin-type globules in the microscale when PEG2000 is used as directing reagent, while spherical aggregates of single crystalline ZnO nanocones are obtainedunder the direction of PEG 200. Studies reveal that both the PEG molecules aggregate to globules by interactingwith zinc species in suitable solvents and englobe the zinc species. By the short time of ultrasonic pretreatmenton the solution, a kind of flagellum structure is induced around the globules, in long tubular shapes for PEG2000 but as shorter wedges for PEG 200. The globules with flagellums are templates for the assembly of theZnO nanotubes or ZnO nanocones in the hydrothermal treatment. The tiny ZnO crystallites, produced in thehydrothermal process, stack to the templates and amalgamate to single crystalline nanotubes or nanocones,similar to the oriented attachment mechanism. The PEG 2000 template is included in the ZnO cavity ofnanotubes, while PEG 200 is excluded from the ZnO nanocones due to the different intertwist propertiesbetween the two PEG molecules. Both the urchin-type assemblies, possessing the same external crystallineplane, compose a isotropic powder and emit very strong yellow light, centered at ~2.1 eV, under the excitationof the He-Cd laser at 325 nm, which has been correlated to the specific crystal plane. The special powderswill be easily coated onto any type of surface for the decoration of a large area of surfaces for future applications.