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目前无机纳米材料的研究主要集中于低维无机纳米材料的制备,如纳米颗粒、纳米纤维等,其制备方法已相当成熟,而对高维特殊形貌无机纳米材料的研究相对较少。近年来,具有特殊形貌的高维无机纳米材料因独特的结构和表面性质在催化、太阳能电池、传感器、微波吸收、医学等领域展现出优于低维纳米材料的性能,但制备出的材料种类少,形貌不均一,可控性较差。因此,研究者们致力于特殊形貌无机纳米材料生长机理的研究,为材料制备提供有效的理论依据。制备无机纳米材料的方法有微乳液法、溶胶-凝胶法、电化学法、水/溶剂热法等。其中水/溶剂热法制备的无机纳米材料具有晶粒发育完整、粒度分布均匀、颗粒之间少团聚、原料价格较便宜的优点,因此被广泛应用于特殊形貌无机纳米材料的制备。自组装技术作为超分子领域的新概念,在制备特殊形貌的材料中发挥着重要作用,其主要作用是将低维的纳米结构单元通过氢键、范德华力、静电力等非共价键作用力进行连接而组装成各种复杂的层级结构。现已通过自组装技术合成了片状、棒状、花状、海绵状、树枝状等特殊形貌无机纳米材料。其中片状材料的生长过程如下:第一步是纳米颗粒的奥斯特瓦尔德熟化过程,第二步是熟化的纳米颗粒定向附着自组装成片状材料。棒状材料的生长过程出现了两种情况,第一种与片状形成过程相同,第二种则是先形成片状,然后片状发生卷曲形成棒状材料,棒状材料再定向附着自组装成长径比不同的棒状材料。花状、海绵状、树枝状等复杂形貌的形成则是基于片状或棒状材料,通过氢键自组装而成。自组装过程会受到表面活性剂或模板剂、溶剂、沉淀剂、酸碱度等因素的影响。研究者们发现利用水热法制备纳米材料时,引入合适的表面活性剂或模板剂,能够促使低维纳米结构单元进行有序自组装而形成结晶度好、尺寸均匀的特殊形貌纳米材料。通过改变表面活性剂或模板剂、溶剂、沉淀剂的种类和剂量及酸碱度等因素,影响纳米颗粒的生长方向、生长速率及颗粒之间的作用力,进而控制产品的形貌和尺寸。本文对近年来国内外利用自组装技术制备特殊形貌无机纳米材料的研究成果进行了介绍,分析讨论了自组装过程的影响因素,并对自组装制备特殊形貌无机纳米材料的发展方向和应用前景进行了展望,以期为制备性能优越的特殊形貌纳米材料提供参考。 相似文献
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利用具有特定结构的物质作为模板,来引导纳米有序结构的制备与组装,从而实现对纳米材料的组成、结构、形貌、尺寸、取向和排布等的控制,为研究纳米有序体系的性质提供了有利途径.模板可以分为软模板和硬模板两种,本文介绍了氧化铝、胶体晶体、胶束、生物大分子等几种常见模板的特点.利用模板法,可以制备金属、合金、氧化物、半导体和聚合物及其复合组份等多种纳米结构有序体系.本文结合我实验室最近的研究工作综述了利用模板法制备纳米有序结构体系的研究进展. 相似文献
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纳米材料是指特征尺寸或晶体尺寸在纳米级的一种超细材料,是由极其细小的颗粒所组成的固体材料。纳米材料因其纳米尺寸和大比表面积等特点,具有许多独特的物理性质和化学性质,被广泛应用于陶瓷、催化、光学、生物医学、环境保护等领域。纳米材料根据规整程度分为规整纳米材料和非规整纳米材料。非规整纳米材料,如静电纺丝制备的纳米纤维材料,具有较高的长径比,而准确地控制纳米材料的直径或者制备直径小于100 nm的纳米材料仍有较大的困难,并且非规整材料具有较低的结构取向性。而规整纳米材料多以阵列的形式呈现,如纳米棒、纳米柱、纳米纤维、纳米球以及核壳包覆等特殊结构,具有结构高度有序、尺寸一致、结构分布均匀等优点。纳米材料的制备方法根据制备手段主要分为物理法(物理粉碎法和物理凝聚法)和化学法(沉淀法、溶胶-凝胶法、模板合成法、自组装法)。模板合成法可以精确控制纳米材料尺寸而且模板可以大量复制,因此,规整纳米材料的制备多采用模板合成法。近年来,以高聚物纳米阵列为敏感元件制备的柔性传感器、纳米发电机、超级电容器和生物医学检测器件等因具有高灵敏度、高精度和小型化等优点而备受关注。本文对多孔阳极氧化铝(AAO)模板和高聚物纳米阵列薄膜的制备方法进行了系统的概述,并对高聚物纳米阵列制备方法的优缺点和应用进行了归纳,还探讨了高聚物纳米阵列的现存问题和应用前景,为AAO模板和高聚物纳米阵列薄膜的制备及应用提供了参考。 相似文献
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纳米银具有独特的热、光、电、磁、催化和敏感等特性,具有广阔的应用前景,是金属纳米材料研究的热点.阐述了制备纳米银的方法,包括化学还原法、光化学还原法、模板法、溶胶-凝胶法、微乳液法、激光烧蚀法等,列举了纳米银在化学反应、光学领域、抗菌领域和作为抗静电材料的主要应用,简述了纳米银制备过程中存在的不足,展望了纳米银合成研究的发展趋势. 相似文献
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Jin‐Yong Hong Hyeonseok Yoon Jyongsik Jang 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(5):679-686
A facile way to synthesize nanometer‐sized polymer (polypyrrole, PPy) particles is explored on the basis of the formation of complexes between water‐soluble polymers and metal cations in aqueous solution. The metal cation is used as an oxidizing agent to initiate the chemical oxidation polymerization of the corresponding monomer, and the water‐soluble polymer effectively provides a steric stability for the growth of polymer nanoparticles during the polymerization process. Light‐scattering analyses are performed to give insight into the behavior of the complexes in aqueous solution. In addition, major physical parameters affecting the formation of polymer nanoparticles are investigated, including hydrodynamic radius, radius of gyration, shape factor, and viscosity. By judicious control of these parameters, PPy nanoparticles with narrow size distribution can be readily fabricated in large quantities. It is also possible to control the diameter of the nanoparticles by changing critical synthetic variables. Importantly, PPy nanoparticles of ≈ 20–60 nm in diameter can be prepared without using any surfactants or specific templates; this novel strategy offers great possibility for mass production of polymer nanoparticles. 相似文献
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Ultrafine amorphous Fe–B alloy nanoparticles are self-assembled within anodic aluminum oxide templates by combining a preparation process of Fe–B nanoparticles with a template method. Scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, X-ray diffraction spectrometry, Mössbauer spectrometry, and vibrating sample magnetometry are employed to study the morphology, chemical composition, structure, and magnetic properties of the nanoparticle assemblies, respectively. The results show that the alloy particles are amorphous with a boron content of 24 at. % and can be in shape of sphere and rod by controlling the duration of preparation. There is a narrow distribution of the sizes of spherical nanoparticles with an average diameter below 35 nm in relatively short preparation time, while rods are found in longer time. The measurements of magnetic properties indicate that the nanoparticles are mostly in superparamagnetic state and the self-assembly of the nanoparticles has a weak magnetic anisotropy with an easy direction perpendicular to the template plane. 相似文献
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In-situ deposition of Pd nanoparticles on tubular halloysite template for initiation of metallization 总被引:1,自引:0,他引:1
Halloysite template has a tubular microstructure; its wall has a multi-layer aluminosilicate structure. A new catalytic method is adopted here, through the in-situ reduction of Pd ions on the surface of tubular halloysite by methanol to initiate electroless plating; the detailed deposition features of Pd nanoparticles are investigated for the first time. The results indicate that an in-situ reduction and deposition of Pd occurs at room temperature, in which the halloysite template plays an important role. Impurities in halloysite (such as ferric oxide) influence the formation and distribution of the Pd nanoparticles. The Pd nanoparticles are of a non-spherical shape in most cases, which would be caused by the irregular appearance of halloysite. No intercalation of the nanoparticles occurs between the aluminosilicate layers in the halloysite. The diameter of Pd nanoparticles increases with time; the average diameter ranges from 1 nm to 4 nm. Pd nanoparticles on a halloysite template can catalyze electroless deposition of Ni to prepare a novel nano-sized cermet at low cost. This practicable catalytic method could also be used on other clay substrates for the initiation of metallization. 相似文献
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《材料科学技术学报》2015,(8)
Hydroxyapatite(HAP) nanoparticles with uniform morphologies and controllable size were synthesized successfully by molecular template hydrothermal approach.The organic alcohols including ethanol,glycol,glycerol and butanol were used as templates to regulate the nucleation and crystal growth.The synthesized powders were characterized by X-ray diffraction,Fourier infrared spectrum and transmission electron microscopy.The results showed that the obtained HAP particles were uniform rod-like crystals,and the template molecular structures had significant effect on the morphology and size of HAP particles.The template molecules with longer hydrophobic groups resulted in longer particle length and larger aspect ratio.Compared with the concentration of template molecules,the template molecular structure showed larger influence on controlling the HAP morphology and size.Furthermore,the formation mechanism of these rod-like HAP particles prepared by alkyl alcohol templates was discussed.Moreover,hydrothermal treatment temperature and time could be also used for controlled preparation of HAP nanoparticles. 相似文献
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Neftali L.V. Carreño Irene T.S. Garcia Elson Longo Leidne S.S.M. Carreño Ricardo C.F.A. Santos 《Materials Letters》2007,61(16):3341-3344
Several attractive types of amorphous or crystalline carbon nanostructure were obtained by a single catalytic process, during natural gas decomposition using different nanostructured catalysts as template. The nanostructured catalyst templates were based on transition metal nanoparticles embedded in carbon matrixes and nanoceramic supports which consist of magnesium oxide doped with ceria rare earths, prepared by the high-energy mechanical milling. The yield and the nature of the nanostructured carbon are strongly influenced by the preparation method of the template and the chemical composition of the catalysts. 相似文献
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CdS nanoparticles have been successfully synthesized by using DNA networks as templates. The synthesis was carried out by first dropping a mixture of cadmium acetate and DNA on a mica surface for the formation of the DNA network template and then transferring the sample into a heated thiourea solution. The Cd(2+) reacted with thiourea at high temperature and formed CdS nanoparticles on the DNA network template. UV-vis spectroscopy, photoluminescence, x-ray diffraction and atomic force microscopy (AFM) were used to characterize the CdS nanoparticles in detail. AFM results showed that the resulted CdS nanoparticles were directly aligned on the DNA network templates and that the synthesis and assembly of CdS nanoparticles was realized in one step. CdS nanoparticles fabricated with this method were smaller than those directly synthesized in a thiourea solution and were uniformly aligned on the DNA networks. By adjusting the density of the DNA networks and the concentration of Cd(2+), the size and density of the CdS nanoparticles could be effectively controlled and CdS nanoparticles could grow along the DNA chains into nanowires. The possible growth mechanism has also been discussed in detail. 相似文献
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This investigation shows that in absence of the chemical reductant and the other protective reagents, the host-guest interaction and the molar ratio of dendrimers/Au3+ other than size and shape of the templates play an important role for the preparation of stable gold hybrid colloids by 60Co γ-ray irradiation using spherical PAMAM-G5 as nonlinear polymeric template. The hybrid colloid resultants comprised of the ordered nano-crystal and the random non-crystal part, which has been confirmed by HRTEM, display spherical structure and the polydispersity of the size distribution in the range of nanometer scale. The dendrimer/gold hybrid colloids are formed by the intramolecular and intermolecular adsorption action between PAMAM-G5 template and gold nanoparticles, respectively. 相似文献
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Masayoshi Fuji Takahiro Shin Hideo Watanabe Takashi Takei 《Advanced Powder Technology》2012,23(5):562-565
Shape-controlled hollow silica nanoparticles have been successfully synthesized by an inorganic particle template method, which involves sol–gel silica coating over surfaces of the template and followed by acid-dissolution removal of the template. This work demonstrates shape control of the hollow particle using calcium carbonate as the template with a variety of shapes such as cubic, rough-surfaced spherical and rod-like particles. Inner size and shape of hollow silica nanoparticles synthesized were exactly reflected to outer size and shape of template used, and existence of micropores in the silica shell wall was verified by nitrogen gas adsorption analysis. 相似文献