Polymer Science Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
Langmuir. 2010 Jun 1;26(11):8769-82. doi: 10.1021/la904507q.
A simple solution-based method to prepare mainly flowerlike zinc oxide (ZnO) nanostructures using the ascorbate ion as a shape-directing/capping agent at relatively low temperature (ca. 30 and 60 degrees C) was described. However, we observed that different shapes of hierarchical ZnO nanostructures such as flowerlike, spindlelike, and spherical could be obtained with an increase in the synthesis temperature from 60 to 90 degrees C. The effects of other organic capping agents on the shape of hierarchical ZnO nanostructures were also studied. FTIR, FESEM, and XRD characterization were performed on the formed ZnO nanostructures to understand the role of ascorbate in the growth of flowerlike morphology. The nucleation and growth process can regulate by changing the metal precursor and ascorbate ion concentrations. We were able to identify intermediate nanostructures such as spherical/quasi-spherical and spindle that are very much on the pathway of formation of large, flowerlike ZnO nanostructures. Electron microscopy results indicated that these spherical/quasi-spherical ZnO nanoparticles might aggregate through oriented attachment to produce spindlelike and flowerlike nanostructures. On the basis of these results, a possible growth mechanism for the formation of flowerlike ZnO nanostructures was described. The optical properties of these differently shaped ZnO nanostructures were also described. The catalytic activities of the as-synthesized spherical and flowerlike ZnO nanostructures were tested in the Friedel-Crafts acylation reaction of anthracene with benzoyl chloride. The catalysis results indicated that the catalytic activity of flowerlike ZnO nanostructures is slightly higher than the spherical counterpart.
一种简单的基于溶液的方法，使用抗坏血酸离子作为形状导向/封端剂，在相对较低的温度（约 30 和 60 摄氏度）下制备主要为花状氧化锌（ZnO）纳米结构。然而，我们观察到，随着合成温度从 60 摄氏度升高到 90 摄氏度，可以得到不同形状的分级 ZnO 纳米结构，如花状、纺锤状和球状。我们还研究了其他有机封端剂对分级 ZnO 纳米结构形状的影响。对形成的 ZnO 纳米结构进行了傅里叶变换红外光谱（FTIR）、场发射扫描电子显微镜（FESEM）和 X 射线衍射（XRD）表征，以了解抗坏血酸在花状形貌生长中的作用。通过改变金属前体和抗坏血酸离子浓度可以调节成核和生长过程。我们能够识别出中间纳米结构，如球形/准球形和纺锤形，这些结构非常接近于形成大花状 ZnO 纳米结构的途径。电子显微镜结果表明，这些球形/准球形 ZnO 纳米颗粒可能通过定向附着聚集形成纺锤形和花状纳米结构。基于这些结果，描述了形成花状 ZnO 纳米结构的可能生长机制。还描述了这些不同形状 ZnO 纳米结构的光学性质。测试了合成的球形和花状 ZnO 纳米结构在蒽与苯甲酰氯的 Friedel-Crafts 酰化反应中的催化活性。催化结果表明，花状 ZnO 纳米结构的催化活性略高于球形对应物。
