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21.
Jijun Qiu Weidong Yu Xiangdong Gao Xiaomin Li 《Journal of Sol-Gel Science and Technology》2007,44(3):235-239
Ordered porous TiO2 films, including TiO2 nanotube arrays, are fabricated by a sol-gel dip-coating approach via ZnO nanorod templates obtained from aqueous solution
approach. The results indicate that the morphologies of ordered porous TiO2 films have been great affected by the sol-gel dip-coating cycle number. Open-ended TiO2 nanotube arrays can be obtained in optimum dip-coating cycle numbers. The TiO2 nanotubes with the inner diameter matching well with the diameters of ZnO nanorods, are well assembled and separate each
other. When the cycle number is less than this optimum value, no intact porous TiO2 film can be obtained. As the cycle number is larger than this optimum value, an ordered porous TiO2 film with many throughout holes is formed. The evolutive mechanism of ordered porous TiO2 films is proposed. 相似文献
22.
Published data on silicon carbide nanotubes (SiC-NT) are analyzed. According to theoretical calculations, single-layer SiC-NTs
do not dissociate, but they have not yet been detected experimentally. According to the experimental data, metastable SiC-NTs
with walls consisting of several layers and nanotube fibers were produced. The optimized structure of single-layer SiC-NTs
was calculated by the RHF/6-31G quantum-chemical method. The possibility of obtaining SiC-NTs by gas-phase chemical deposition
from methyltrichlorosilane in the temperature range of 800–1000 °C was investigated. Nanofibers and polygrained SiC nanotubes
were obtained, but ordinary layer SiC nanotubes were not detected. To remove the inconsistencies it was first proposed to
classify the nanotubes according to the structure of their walls, separating all the SiC-NTs into three types: 1) ordinary
layer nanotubes with rolled layers, similar to carbon nanotubes; 2) polynanocrystalline nanotubular fibers or nanotubes with
walls consisting of linked differently oriented nanograins; 3) monocrystalline synthetic nanotubes with ideal crystalline
walls. It was concluded that the ordinary SiC-NTs of the first type are unstable with the exception of one-or two-layer nanotubes;
stable SiC-NTs of the first type and SiC-NTs of the third type have not yet been discovered; only nanotubular fibers of the
second type were obtained experimentally.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 3–13, January–February, 2006. 相似文献
23.
Xinhuan Yan Junqing Sun Yongbin Fang Zhenyuan Xu Wenjing Wang 《Frontiers of Chemistry in China》2006,1(1):41-44
The Pt-Sn-B/carbon nanotubes (CNTs) catalyst was prepared by impregnation-chemical reduction method. Its catalytic performance
was evaluated by liquid-phase hydrogenation of chloronitrobenzene (CNB). The results showed that the catalyst had higher catalytic
performance than common hydrogenation catalysts. The conversion of CNB could reach 99.9%, and the dechlorination of chloroaniline
(CAN) was less than 1.9% when catalyzed by Pt-Sn-B/CNTs and more than 8.0% when catalyzed by common hydrogenation catalysts.
X-ray diffraction and selected area electron diffraction analysis showed that Pt-Sn-B/CNTs had an amorphous alloy structure
that can improve catalytic performance. Transmission electron micrograph image showed that the catalyst particles were highly
distributed on the surface of CNTs. The hydrodechlorination of CNB was mainly affected by the unique structure of CNTs and
the nature of the amorphous metals on the surface of CNTs. The relationship between the interaction of CNTs and amorphous
metals and the catalytic performance of the catalyst is also discussed.
Translated from the Chinese Journal of Catalysis, 2005, 26(3) (in Chinese) 相似文献
24.
通过有机物分解碳化处理TiO2 纳米管制得了TiO2C, 并以其为载体制备了Pd/TiO2C电催化剂,考察了该催化剂对碱性介质中乙醇电催化氧化的活性. 结果表明,碳化导电处理的TiO2C纳米管载体能有效改善催化剂中贵金属的分散度和电极结构,从而提高催化剂的电催化活性. 对催化剂活性组分的优化实验表明, Pd/TiO2C质量比为1/1时催化剂的活性最高. 在1 mol/L KOH溶液中Pd载量均为0.3 mg/cm2的条件下, Pd/TiO2C催化剂对乙醇氧化的催化活性是Pd/C催化剂的3.8倍. 相似文献
25.
Flow field-flow fractionation (flow FFF), a separation technique for particles and macromolecules, has been used to separate carbon nanotubes (CNT). The carbon nanotube ropes that were purified from a raw carbon nanotube mixture by acidic reflux followed by cross-flow filtration using a hollow fiber module were cut into shorter lengths by sonication under a concentrated acid mixture. The cut carbon nanotubes were separated by using a modified flow FFF channel system, frit inlet asymmetrical flow FFF (FI AFIFFF) channel, which was useful in the continuous flow operation during injection and separation. Carbon nanotubes, before and after the cutting process, were clearly distinguished by their retention profiles. The narrow volume fractions of CNT collected during flow FFF runs were confirmed by field emission scanning electron microscopy and Raman spectroscopy. Experimentally, it was found that retention of carbon nanotubes in flow FFF was dependent on the use of surfactant for CNT dispersion and for the carrier solution in flow FFF. In this work, the use of flow FFF for the size differentiation of carbon nanotubes in the process of preparation or purification was demonstrated. 相似文献
26.
In Yee Phang Tianxi Liu Wei-De Zhang G. Julius Vancso 《European Polymer Journal》2007,43(10):4136-4142
Multi-walled carbon nanotubes (MW-CNT) inside a polyamide-6 (PA6)-MW-CNT composite were visualized by atomic force microscopy (i) in a field-assisted intermittent contact and (ii) in the tunneling (TUNA) mode. Individual buried MW-CNTs were clearly discerned within the PA6 matrix. An average diameter of 33 ± 5 nm of the MW-CNTs was determined based on field-assisted intermittent contact mode AFM images, which is consistent with the expected size of PA6-coated MW-CNTs. Single well dispersed MW-CNTs that are located in the sub-surface region of the composite were also observed in the TUNA mode. These new AFM approaches circumvent the tedious sample preparation based on ultramicrotoming required for high resolution electron microscopy studies to obtain “in-depth” morphological information and hence are expected to facilitate the analysis of CNT-based and other nanocomposites in the future. 相似文献
27.
从碳纳米管的电性质出发,对以它为填料的导电性复合材料的制备方法和研究进展进行了综述,同时简单介绍了导电性复合材料电性质转变现象的理论分析模型,最后对碳纳米管/高分子复合导电材料的研究前景作了一定探讨。 相似文献
28.
ZnO nanotubes were synthesized in large scale by thermal decomposition of the precursors obtained via chemical reaction between Zn(CH3COO)2·2H2O and NaHCO3 in the presence of surfactant sodium dodecyl sulfate (SDS). The inner diameters of the tubes were in the range of 80~100 nm, and outer diameters in the range of 160~260 nm with lengths up to a few micrometers. The products were characterized with XRD, TEM, and SEM. 相似文献
29.
以ZnO纳米柱阵列为模板, 采用溶胶-凝胶法制备出TiO2/ZnO和N掺杂TiO2/ZnO的复合纳米管阵列. 扫描电镜(SEM)、X射线光电子能谱(XPS)和紫外-可见漫反射吸收光谱(UV-Vis)的结果表明: 两种阵列的纳米管均为六角形结构, 直径约为100 nm, 壁厚约为20 nm; 在N-TiO2/ZnO复合纳米管阵列中, 掺入的N离子主要是以N-Ox、N-C和N-N的形式化学吸附在纳米管表面, 仅有少量的N离子以取代式掺杂的方式占据TiO2晶格O的位置; 表面N物种形成的表面态能级和取代式掺杂导致带隙的窄化, 增强了纳米管阵列的光吸收效率, 促进了光生载流子的分离. 光催化实验结果表明, N离子的掺杂有利于N-TiO2/ZnO复合纳米管阵列光催化活性的提高. 相似文献
30.
碳纳米管电极超大容量离子电容器交流阻抗特性 总被引:18,自引:0,他引:18
采用碳纳米管作为超大容量离子电容器的电极材料,应用交流阻抗频谱法,研究了超大容量离子电容器的频率响应特性.结果表明,用碳纳米管块作电极,超大容量离子电容器在频率250 mHz以下出现“电荷饱和”;而用活性炭块作电极, 超大容量离子电容器在频率为100 mHz时仍未出现“电荷饱和”,这说明碳纳米管电极超大容量离子电容器的频率响应特性优于活性炭电极超大容量离子电容器的频率响应特性.上述两类超大容量离子电容器的阻抗谱中均出现倾角约为45°的直线段,其相位角均远小于理想电容器的相位角90°. 相似文献