ZnO纳米环的可控合成

以六次甲基四胺(Hexamethylenetetramine, C6H12N4)和水合硝酸锌[Zn(NO3)2·2H2O]为原料, 表面活性剂聚丙烯酰胺-氯化二烯丙基二甲基铵[poly(acrylamide-co-diallyldimethylammonium chloride, 缩写为PAM-CTAC]为形貌控制剂, 采用液相沉淀法合成了ZnO纳米环. 产物的结构与形貌经X射线粉末衍射(XRD)和扫描电子显微镜(SEM)表征. 研究了不同实验条件(如表面活性剂的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-CTAC作用下ZnO纳米环可能的形成机理. 结果表明, 合成产物为六方Wurtzite型结构的ZnO纳米环, 环内径约为220 nm, 壁厚约为70 nm. 反应物浓度、反应温度对ZnO纳米环的形成以及纳米环的尺寸都有一定的影响, 但起关键作用的是PAM-CTAC. 通过改变PAM-CTAC的浓度, 能有效地实现ZnO纳米环的可控合成. 室温荧光光谱显示, ZnO纳米环的紫外发射峰具有较窄的半高宽(FWHM)(约7 nm), 表明合成产物具有较窄的尺寸分布.

Controlled-synthesis of ZnO Nanorings

ZnO nanorings were prepared on a large scale by a facile solution-based method at 70 ℃ for 5 h via hexamethylenetetramine(C6H12N4) and Zn(NO3)2·2H2O as the raw materials in the presence of surfactant PAM-CTAC. The structure and morphology of as-prepared products were characterized by X-ray powder diffraction(XRD) and scanning electron microscopy(SEM). The studies of the influences of experimental conditions such as concentration of surfactant and reactants, reactive temperature and time on the structure and morphology of as-prepared products were carried out. Probable formation mechanism of ZnO nanoring in the presence of surfactant PAM-CTAC was discussed. The results show that as-prepared products are wurtzite hexagonal structure ZnO nanorings with the inner diameter of 220 nm and the wall thickness of nanoring of 70 nm. Reaction temperature and concentration of reactants have influence on the formation and size of ZnO nanorings, but the surfactant PAM-CTAC plays the key role in the formation of ZnO nanorings. Through adjusting the concentration of PAM-CTAC, ZnO nanorings can be synthesized under control. A room temperature FL spectrum of ZnO samples shows that the full width at half maximum(FWHM)(~7 nm) of the UV emission is much narrower than that of commercial ZnO bulk crystals(~18 nm), the narrow FWHM confirms the uniformity and narrow size distribution of the as-synthesized ZnO crystals.