二氧化钛胶粒嵌入超细层状钛酸盐制备金红石型氧化钛纳米纤维中英文混合版.docx

1、二氧化钛胶粒嵌入超细层状钛酸盐制备金红石型氧化钛纳米纤维中英文混合版Preparation of rutile TiO2 nanofibers by TiO2 sol intercalation of ultrafine layered titanate二氧化钛胶粒嵌入超细层状钛酸盐制备金红石型氧化钛纳米纤维Juan Yang（杨娟）, Qinqin Liu（刘芹芹）, Xiujuan Sun（孙秀娟）江苏大学材料科学与工程学院，江苏镇江，邮编：2120132006五月17日收到； 2006年7月23日接受；2006年8月15日开始在线使用AbstractTo prepare TiO2 int

2、ercalated tetratitanate, TiO2 solution and ultrafine layered titanate K2Ti4O9 obtained via solid-state reaction by using nanometer-sized TiO2 as raw material were used as guest and host materials respectively. The structure and morphology of the resulting samples were characterized by XRD and TEM ex

3、periments. It was found that during the intercalation process, the interlayer distance was expanded step-by-step and the interlayer structure of titanate might be destroyed and degraded to slits by prolonging the solution intercalation time. Rutile TiO2 nanofibers with the average size of 550 nm wer

4、e obtained at room temperature while the duration time was prolonged to 72 h. 2006 Elsevier B.V. All rights reserved.摘要：为了制备二氧化钛嵌入钛酸盐（tetratitanate）材料，用二氧化钛溶胶和超细层状K2Ti4O9分别作为主体和辅体原料进行固相反应得到纳米二氧化钛。对试样的结构和形貌进行了XRD和TEM表征。研究结果表明，嵌入过程中，延长嵌入时间，层间距离会逐步增大，钛酸盐夹层结构被破坏然后微裂纹空隙中被微小粒子嵌入。室温下持续72小时可得到平均尺寸约为550nm的金红

5、石型TiO2纳米纤维。 2006 Elsevier B.V保留所有权利。Keywords: Rutile TiO2 nanofiber; Ultrafine layered titanate; Sol intercalation关键词：金红石纳米纤维；超细分层钛酸盐；溶胶插入法1. IntroductionRecently, the pillaring of sol particles into layered inorganic solids has received considerable attention, since this provides a useful strategy

6、to create novel porous materials and inorganic/organic nanocomposites 1-3. It has been reported that the introduction of small semiconducting particles of CdS-ZnS, Fe2O3 and TiO2 into the interlayer of layered materials such as montmorillonite, smectite clays, layered niobate and layered titanate gi

7、ves rise to a remarkable enhancement of their photocatalytic activity compared with unsupported catalyst 2,4-7. Among them, layered titanates have been extensively studied due to their applications in photocatalysts and catalyst supports8,9. But the intercalation of layered titanates is not easy to

8、achieve since these types of layered materials do not possess swelling ability due to their high charge density 10. New methods are explored to improve the intercalation property of layered titanates. In our study, it is found that the intercalation property of layered titanate might be influenced b

9、y the particle size of titanate. Al13O4(OH)24(H2O)127+ (Al137+) and NH2(CH2)3Si(OC2H5)3 (APS) were easily introduced into the interlayer of the host material K2Ti4O9 with relatively small particle size about 70 nm600 nm 11,12. 前言最近，杆状溶胶粒子嵌入无机固体材料的研究，因其为生产新型多孔材料和无机/有机纳米复合材料提供了一个有益的战略方针，而得到了广泛的关注1-3。据

10、报道，将细小的CdS-ZnS, Fe2O3 和 TiO2等半导体材料引入蒙脱石、蒙皂石粘土、层状铌盐酸和层状钛酸盐等层状物质的层间可以显著的增强光触媒的光催化活性 2,4-7 。其中的层状钛酸盐因其可用作光触媒和光触媒载体而得到了广泛的研究8,9。但是，这些层状材料的高电荷密度造成的低热膨胀率，使得（溶胶粒子）嵌入层状钛酸盐很难实现10。新的试验试探提高了层状钛酸盐的嵌入性能。我们在研究中发现，层状钛酸盐的嵌入性能和钛酸盐的粒径大小有关。粒径在70 nm600 nm 左右的纳米Al13O4(OH)24(H2O)127+ (Al137+) 和NH2(CH2)3Si(OC2H5)3 (APS)能够

11、很容易的引入主体材料K2Ti4O9的层间11,12。According to our knowledge about nano-materials, peculiar properties differing from bulk materials may appear as the dimension of the materials is reduced to the submicrometer or nanometer scale. In our previous study, since the intercalation property is enhanced by decreas

12、ing the particle size of the host material, the exfoliation property might also be influenced. It is reported that the exfoliated nanosheets can be used as building blocks to construct self-assembled multilayers and to produce nanotubes 1315. If the ultrafine layered titanate can be exfoliated to na

13、nosheets or degraded to nanoslits easily during the sol particles intercalation process, some new nanostructural materials might be obtained. 据纳米材料的相关知识可知，亚微米或纳米尺度的散装材料会呈现出一些和常规尺寸材料不同的特殊性质。我们以往的研究表明，减少主体材料的粒径不仅会增强嵌入性能，还会影响材料的的剥离性能。据相关文献可知，脱落的纳米片可用作构建块构建多层自组装膜和纳米管13-15。如果胶粒在插入过程中，超细层状钛酸盐能够很容易的剥离成纳米片或

14、侵蚀出微裂纹，那么将会出现一些新的纳米结构材料。In this report, ultrafine layered titanate K2Ti4O9 is really degraded to nano-slits easily during the pillaring process for preparing TiO2-pillared titanate. By prolonging the duration time, rutile TiO2 nanofibers are obtained and the mechanism is also discussed.我们的研究表明，超细层状钛

15、酸盐K2Ti4O9能够很容易的在柱化过程中形成二氧化钛柱撑钛酸盐结构。延长持续时间，可以获得纳米金红石型二氧化钛纤维，本文还对相关机理进行了讨论。2. Experimental2.实验部分2.1. Preparation of rutile TiO2 nanofibers2.1.制备金红石型TiO2纳米纤维Ultrafine layered tetratitanate K2Ti4O9, protonated K2Ti4O9(H2Ti4O9H2O) and n-propylamine (C3H7NH2) incorporated products (denoted as amine-Ti) we

16、re prepared as described in Ref. 12.超细层状K2Ti4O9，酸化的K2Ti4O9 (H2Ti4O9H2O)和正丙胺(C3H7NH2)等选用产品见文献综述12的描述。To intercalate TiO2, 0.4 g n-propylamine intercalated titanates were mixed with TiO2 sol which was prepared as follows: 8.5 g Ti(OC4H9)4 was added dropwise to 100 mL 0.1 M HCl aqueous solution with vi

17、gorous stirring and the stirring was continued at room temperature for 3 h. The resultant mixture was kept stirred for 1272 h, followed by centrifuging and washing with distilled water. The obtained products (denoted as sol-Ti) were dried in a vacuum at 30 C.嵌入TiO2的过程，首先按照如下方法制备TiO2溶胶：将8.5g Ti(OC4H9

18、)4滴入快速搅拌的100ML 0.1M 的盐酸溶液中并在室温下继续搅拌3h，然后将0.4g正丙胺钛酸酯与上面制得的TiO2溶胶混合，再将混合物搅拌712小时，最后离心沉淀、蒸馏水洗涤、30下真空干燥得到TiO2溶胶。2.2. Characterization2.2.特征鉴定The layered structure of the original and intercalated titanates were identified by X-ray powder diffraction (XRD) analysis (Rigaku D/max2500) using Cu-K radiation

19、 (=0.15406 nm). The morphology was observed on a PHILIPS LNAI-12 Transmission electron microscopy (TEM) using 175 kV acceleration voltage. 钛酸盐的起始层状结构和嵌入后的结构将会使用日本理学D/max2500（Rigaku D/max2500，Cu-K射线，=0.15406 nm）的XRD衍射仪进行分析。形貌特征用飞利浦LNAI-12（PHILIPS LNAI-12，加速电压=175kV）TEM进行表征。Fig. 1. XRD patterns of (a)

20、 K2Ti4O9, (b) H-Ti, (c) amine-Ti and (d) sol-Ti图1. (a) K2Ti4O9, (b) H-Ti, (c) amine-Ti 和 (d) sol-Ti的XRD衍射图Fig. 2. TEM image of sol-Ti products heat-treated at 500 C for 2 h.图2.500下热处理了两个小时的sol-Ti的TEM扫描图象Fig. 3. TEM image of rutile TiO2 nanofibers图.3.金红石型纳米二氧化钛纤维的TEM扫描图象3. Results and discussion3.结果与

21、讨论XRD patterns of ultrafine K2Ti4O9 and the intercalated products are shown in Fig. 1. The XRD pattern of ultrafine K2Ti4O9 Fig. 1(a) is in good agreement with that of K2Ti4O9 (JCPDS 32-0861) and the first diffraction peak is at 2=10.05, suggesting that the interlayer distance is about 0.89 nm. Afte

22、r exchanging K+ with H+ in 1 M HCl solution, H3O+ was introduced to the interlayer and the interlayer distance is increased to 1.04 nm Fig. 1(b). In Fig. 1(c), n-propylamine readily intercalates the tetratitanate and leads to extremely strong peak at 2=5.45, the interlayer distance is about 1.62 nm.

23、 After reacting with TiO2 solution at room temperature for 12 h, the interlayer distance is decreased to 1.10 nm due to the exchanging of n-propylamine by relatively small TiO2 sol particles and the relatively weak intensity suggests that the layered structure might be destroyed. 超细层状钛酸盐K2Ti4O9及相关的嵌

24、入结构产物的XRD衍射图象见图1。超细层状钛酸盐K2Ti4O9的XRD衍射图图1（a）和K2Ti4O9 的标准XRD衍射图样(JCPDS 32-0861)吻合很好，第一个衍射峰为2=10.05，表明层间距离约为0.89nm，当在1M的盐酸溶液中，K+和H+交换后，H3O+将会嵌入层间，层间距离将会增至1.04nm 图. 1(b)。在图. 1(c)中，正丙胺嵌入层状钛酸盐中导致出现了极强的衍射峰2=5.45，层间距离约为1.62nm。当同TiO2溶胶在死室温下反应12h后，层间距离将会降至1.10nm左右。这是因为正丙胺被比较小的TiO2溶胶粒子置换，层间键强消弱，这意味着层间结构可能会遭到破坏

25、。 Fig. 2 shows the TEM image of TiO2 sol particles intercalated products further heat-treated at 500 C for 2 h. The morphology of the host K2Ti4O9 material is whisker-like and the length of the whiskers is in the range from 200 nm to 600 nm while the width of most whiskers is approximately 70 nm 12.

26、 It is found that the morphology is extensively influenced by the pillaring of TiO2 particles. In Fig. 2 part A, it can be seen that the layered structure was maintained and the slits were expanded significantly by the intercalation process. Furthermore, a few nanometer-sized slits were also observe

27、d in part B. It has been reported that layered compounds can degrade from a layered structure to a gel solution during the incorporation of water and/or long-sized molecules 9. In our experiments, the layered structure of ultrafine K2Ti4O9 was partly degraded into nanometer-sized slits and it might

28、be caused by the small size effect of the titanate together with the function of the interlayer TiO2 sol particles. So we consider that the layered structure might be entirely degraded to nanometer-sized slits by prolonging the intercalation time and this assumption was confirmed by our experiments.

29、 图2是在500下热处理两个小时后的TiO2溶胶颗粒的TEM扫描图像。主体材料K2Ti4O9的形貌特征呈须状，晶须长度约70nm12。据了解，显微形貌受TiO2柱状粒子的影响很大。从图2的A部分中可以观察到，在嵌入过程中，分层结构可以保持原状而微裂纹会随嵌入过程扩大。B部分表明，还能观察到一些纳米尺度的微裂纹。据相关文献，在水分子与大分子物质进入层间的过程中，能将复合嵌入结构从层状结构降解为凝胶。在我们的试验中，TiO2纳米胶粒部分的进入超细层状钛酸盐K2Ti4O9的层状结构的纳米级微裂纹之中，这可能是钛酸盐的小尺寸效应及层间TiO2胶粒的作用共同作用造成的。因此，我们认为，延长嵌入时间，层状

30、结构能够极大地侵蚀出纳米尺寸的微裂纹，这个假设被我们的实验所证实。Fig. 3a shows the TEM image of products obtained by intercalation of TiO2 sol particles for 72 h followed by centrifuging and washing with distilled water. It can be seen that the layered structure almost does not exist and the mono-dispersed powders is fiber-like wi

31、th an average size of 550 nm. Fig. 3b is the electron diffraction image of the obtained fiber-like powders indicating the polycrystalline structure. To further validate the crystalline structure, XRD experiment was carried out and the result is shown in Fig. 4. It can be seen that the XRD pattern is

32、 in agreement with rutile TiO2 (JCPDS 4-0551) indicating that in our experiment rutile titanium dioxide could be obtained at room temperature. Moreover the broadened peak indicates the small size of the obtained rutile TiO2, which is in agreement with the TEM result. For crystalline TiO2, there are three polymorphs: rutile, anantase and brookite and the rutile phase is the thermodynamically stable phase usually obtained by calcining at 500 C800 C. But in our experiment, the rutile phase could be obtained without ca