Department of Chemical and Biochemical Engineering University of Western Ontario London, Ontario, Canada N6A 5B9.
Langmuir. 2010 Dec 21;26(24):19014-21. doi: 10.1021/la102048j. Epub 2010 Nov 23.
The growth mechanism of one-dimensional metal oxide nanotubular structures is of tremendous current interest to tailor materials using "green" synthetic procedures for emerging industries in alternative energy and biomaterials. In this study, ZrO(2)-modified TiO(2) nanorods and tubular structures were successfully synthesized via a surfactant-free sol-gel route using supercritical carbon dioxide (scCO(2)) as the solvent/drying agent. The effect of metal alkoxide concentration (0.35-1.4 mol/L), acid/metal alkoxide ratio (R = 3-7), and Zr ratio (0-20%) was examined on the morphology and crystallinity of the resulting nanostructures as measured by electron microscopy (SEM and TEM), EDX, XPS, and XRD. The electron microscopy results showed that the crystal growth of the synthesized binary Ti-Zr nanomaterials could be tailored by changing the operating variables with nanotubular structure formed at metal alkoxide concentration of 1.2 mol/L, R = 5-6, and Zr ratio between 4% and 20%. Gelation kinetics for this new system was also studied and revealed that increasing alkoxide concentration and R value enhanced the gelation kinetics. In situ and powder FTIR results revealed that this Ti-Zr binary system follows a similar reaction scheme to that of either single-component system, showing the flexibility of this approach for tailoring nanotubular production.
一维金属氧化物纳米管状结构的生长机制是当前的研究热点，通过“绿色”合成工艺来定制材料，以满足新能源和生物材料等新兴产业的需求。在这项研究中，我们成功地通过无表面活性剂的溶胶-凝胶法，使用超临界二氧化碳（scCO2）作为溶剂/干燥剂，合成了 ZrO2 修饰的 TiO2 纳米棒和管状结构。通过电子显微镜（SEM 和 TEM）、EDX、XPS 和 XRD 等手段，考察了金属醇盐浓度（0.35-1.4 mol/L）、酸/金属醇盐比（R=3-7）和 Zr 比（0-20%）对所得纳米结构形貌和结晶度的影响。电子显微镜结果表明，通过改变操作变量，可以控制合成二元 Ti-Zr 纳米材料的晶体生长，在金属醇盐浓度为 1.2 mol/L、R=5-6 和 Zr 比为 4%-20%的条件下，可以形成纳米管状结构。还研究了该新体系的凝胶动力学，结果表明增加醇盐浓度和 R 值可以提高凝胶动力学。原位和粉末 FTIR 结果表明，该 Ti-Zr 二元体系遵循与单一体系相似的反应方案，表明该方法在定制纳米管生产方面具有灵活性。
