共查询到20条相似文献,搜索用时 15 毫秒
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Georgios Pilatos Eleni C. Vermisoglou Georgios E. Romanos Georgios N. Karanikolos Nikos Boukos Vlassis Likodimos Nick K. Kanellopoulos 《Advanced functional materials》2010,20(15):2500-2510
Although hollow nanostructures, such as nanotubes, represent a major portion of nanoscaled materials with a tremendously large application range, a detailed evaluation of their internal characteristics still remains elusive. Transmission electron microscopy is the most common analytical technique to examine the internal configuration of these structures, yet it can only provide evidence of a minimal portion of the overall material, thus, it cannot be accurately generalized. In the present paper, in addition to electron microscopy and other spot‐size analysis methods (X‐ray diffraction, Raman spectroscopy, etc.), a combination of techniques including adsorption, permeability, and relative permeability are employed in order to provide important insights into various crucial details of the overall internal surface and hollow‐space characteristics of carbon nanotube (CNT) arrays and membranes. The CNT arrays are fabricated using anodized alumina as a template in a flow‐through chemical vapor deposition (CVD) reactor. This is the first systematic approach for investigating the internal configuration of template‐based CNT arrays in detail. Key findings are made for the customized optimization of the resulting nanotube membranes for a variety of applications, including separations, nanofluidics and nanoreactors, biological capturing and purification, and controlled drug delivery and release. 相似文献
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Nanda Gopal Sahoo Henry Kuo Feng Cheng Lin Li Siew Hwa Chan Zaher Judeh Jianhong Zhao 《Advanced functional materials》2009,19(24):3962-3971
A novel approach to chemically functionalize multiwalled carbon nanotubes (MWCNTs) for making advanced polymeric nanocomposites with liquid crystalline polymers (LCPs) is presented. In this approach, two types of chemical moieties (i.e., carboxylic and hydroxyl benzoic acid groups) are selectively introduced onto the sidewalls of the MWCNTs. Fourier transform IR and Raman spectroscopy are used to examine the interaction between the functionalized MWCNTs and the LCP. The strong interaction between the functionalized MWCNTs and the LCP greatly improved the dispersion of MWCNTs in the polymer matrix as well as the interfacial adhesion. The dispersion of the MWCNTs in the LCP matrix is observed by optical microscopy and field‐emission scanning electron microscopy. As a result, the addition of 1 wt% MWCNTs in the LCP resulted in the significant improvement (41 and 55%) in the tensile strength and modulus of the LCP. 相似文献
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Jung Woo Lee Ravindranath Viswan Yoon Jeong Choi Yeob Lee Se Yun Kim Jaehun Cho Younghun Jo Jeung Ku Kang 《Advanced functional materials》2009,19(14):2213-2218
Using conventional methods to synthesize magnetic nanoparticles (NPs) with uniform size is a challenging task. Moreover, the degradation of magnetic NPs is an obstacle to practical applications. The fabrication of silica‐shielded magnetite NPs on carbon nitride nanotubes (CNNTs) provides a possible route to overcome these problems. While the nitrogen atoms of CNNTs provide selective nucleation sites for NPs of a particular size, the silica layer protects the NPs from oxidation. The morphology and crystal structure of NP–CNNT hybrid material is investigated by transmission electron microscopy (TEM) and X‐ray diffraction. In addition, the atomic nature of the N atoms in the NP–CNNT system is studied by near‐edge X‐ray absorption fine structure spectroscopy (nitrogen K‐edge) and calculations of the partial density of states based on first principles. The structure of the silica‐shielded NP–CNNT system is analyzed by TEM and energy dispersive X‐ray spectroscopy mapping, and their magnetism is measured by vibrating sample and superconducting quantum interference device magnetometers. The silica shielding helps maintain the superparamagnetism of the NPs; without the silica layer, the magnetic properties of NP–CNNT materials significantly degrade over time. 相似文献
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纳米碳管的STM研究 总被引:1,自引:0,他引:1
本文应用扫描隧道显微镜对孤光放电方法得到的纳米碳管进行了观察。孤光放电法所产物的纳米碳管以直线型为主,并且多以束状存在。碳管束直径约20nm,而单要碳管的直径大多在2nm到5nm之间。观察到单层碳秋的原子像,其表明为石墨网络的六角结构。纳米碳管的原子像及单极碳管表面均未发现明显缺陷存在,这可能是它具有很高强度质量比的主要原理之一。 相似文献
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A. Ambrosio M. Ambrosio G. Ambrosone V. Carillo U. Coscia V. Grossi P. Maddalena M. Passacantando E. Perillo A. Raulo S. Santucci 《Materials Science in Semiconductor Processing》2008,11(5-6):187
We report first results on a prototype radiation detector made of multi-walled carbon nanotubes grown on a sapphire substrate. Signals induced in nanotubes by a pulsed laser beam have been collected and analyzed. The optical and electrical inactivity of the substrate material highlights the role of nanotubes. 相似文献
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Julie Tzu‐Wen Wang Laura Cabana Maxime Bourgognon Houmam Kafa Andrea Protti Kerrie Venner Ajay M. Shah Jane K. Sosabowski Stephen J. Mather Anna Roig Xiaoxing Ke Gustaaf Van Tendeloo Rafael T. M. de Rosales Gerard Tobias Khuloud T. Al‐Jamal 《Advanced functional materials》2014,24(13):1880-1894
Carbon nanotubes (CNTs) are one of the most promising nanomaterials to be used in biomedicine for drug/gene delivery as well as biomedical imaging. This study develops radio‐labeled, iron oxide‐decorated multiwalled CNTs (MWNTs) as dual magnetic resonance (MR) and single photon emission computed tomography (SPECT) contrast agents. Hybrids containing different amounts of iron oxide are synthesized by in situ generation. Physicochemical characterisations reveal the presence of superparamagnetic iron oxide nanoparticles (SPION) granted the magnetic properties of the hybrids. Further comprehensive examinations including high resolution transmission electron microscopy (HRTEM), fast Fourier transform simulations, X‐ray diffraction, and X‐ray photoelectron spectroscopy assure the conformation of prepared SPION as γ‐Fe2O3. High r2 relaxivities are obtained in both phantom and in vivo MRI compared to the clinically approved SPION Endorem. The hybrids are successfully radio labeled with technetium‐99m through a functionalized bisphosphonate and enable SPECT/CT imaging and γ‐scintigraphy to quantitatively analyze the biodistribution in mice. No abnormality is found by histological examination and the presence of SPION and MWNT are identified by Perls stain and Neutral Red stain, respectively. TEM images of liver and spleen tissues show the co‐localization of SPION and MWNTs within the same intracellular vesicles, indicating the in vivo stability of the hybrids after intravenous injection. The results demonstrate the capability of the present SPION–MWNT hybrids as dual MRI and SPECT contrast agents for in vivo use. 相似文献
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碳纳米管的生长通常使用Fe,Co,Ni作为催化剂,除此以外的一些过渡元素也能催化裂解生长碳管。其中用铜制备的碳管阈值电场低、发射电流密度大、发射均匀性好等等良好的场发射特性。铜与硅、或金属之间具有很强的的扩散特性,而碳管应用于场发射显示器必然使用玻璃、硅片作为衬底,所以需要一层缓冲层阻挡催化剂铜扩散入衬底。本文使用磁控溅射制备铜薄膜作为催化剂,化学气相沉积方法裂解乙炔生长碳管薄膜形成场发射阴极。并试验W,Ni,Cr和Ti作为铜薄膜的缓冲层,结果表明不同的金属阻挡特性不同,生长后碳管的形貌和特性都有差异。结果表明Ti和W能很好地阻挡铜的扩散,从而使铜催化裂解出附着性好、分布均匀、密度适中、场发射特性良好的碳管薄膜。对于Ni和Cr金属,由于生长的碳管与衬底结合差或者场发射能力差而不适合作铜的缓冲层。 相似文献
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Shaoying He Junqin Huang Qiang Zhang Wan Zhao Zhiai Xu Wen Zhang 《Advanced functional materials》2021,31(41):2105198
In this paper, an artificial nanozyme with efficient oxidase-mimicking activity is developed to investigate antibacterial performance. The bamboo-like nitrogen-doped carbon nanotubes encapsulating cobalt nanoparticles (N-CNTs@Co) are synthesized by pyrolysis of cobalt cyanide cobalt at high temperature. It is found that the oxidase-mimicking activity of N-CNTs@Co is higher than that of iron-centered nanomaterials synthesized by pyrolysis of prussian blue under the same conditions, confirming that the oxidase-mimicking activity is not only related to the active center, but also closely related to its morphology. In addition, the oxidase-mimicking activity of N-CNTs@Co is 12.1 times higher than that of the most reported CeO2. N-CNTs@Co can catalyze oxygen to produce a large number of reactive oxygen species (ROS) under acidic conditions, resulting in a favorable antibacterial effect against two representative bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli). Because the bacterial membrane is damaged by the attack of ROS, the DNA is degraded, eventually causing the bacteria to die. Antibacterial experiments last for 20 days, nevertheless, S. aureus and E. coli do not develop resistance to N-CNTs@Co. The experiments of wound healing in vivo further confirm the high antibacterial efficiency of N-CNTs@Co. 相似文献
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A novel biosensor based on magnetic nanoparticles (MNPs) functionalized with tyrosinase in an operational synergy with a multiwalled carbon nanotube (MWCNT) network is developed. An on–off external magnetic field is applied to a screen‐printed electrode (SPE), which is used as a transducing platform. This enables an interesting on‐demand biosensing performance. The effect of each component on the response of the developed device is carefully evaluated; particularly interesting results are presented for the contributions of MNPs and carbon nanotubes. A tyrosinase‐based model biosensing approach is used, while a potential of ?0.15 V versus Ag/AgCl for the electrochemical reduction of the enzyme products (quinone forms) onto the magnetoswitchable SPE/MNP/Tyr/MWCNT system is applied. The response of the biosensor to catechol is also evaluated; a limit of detection (signal to noise ratio (S/N) = 3) for catechol is found to be around 7.61 μM (S/N = 3) with a relative standard deviation (RSD) of 4.91% (n = 3). The developed device could open the door to a wide range of novel electrocatalytic and bioelectrocatalytic applications of magnetocontrolled redox enzymes. Furthermore, it could be used in miniaturized and portable biosensing systems, such as lab‐on‐a‐chip devices, in medical and environmental applications that have a restricted quantity of sample. Further applications could be envisaged for many other fields, such as external control of catalytic transformations in bioreactors, tailoring of reversible amperometric immunosensors, regeneration of enzyme‐biosensor electrodes, and external triggering of biofuel cells. 相似文献
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Tian‐Chi Chen Meng‐Qiang Zhao Qiang Zhang Gui‐Li Tian Jia‐Qi Huang Fei Wei 《Advanced functional materials》2013,23(40):5066-5073
The high‐end applications of single‐walled carbon nanotubes (SWCNTs) are hindered by the existence of large amount of impurities, especially the graphene layers encapsulating metal nanoparticles (metal@C NPs). The role of working metal catalysts during chemical vapor deposition (CVD) growth and post purifications by oxidation are not yet fully understood. Herein, the in situ monitoring the role of working metal catalyst NPs for ultrahigh purity SWCNTs by CVD growth and CO2 purifications is carried out in an online thermogravimetric reactor attached with a mass spectrometer. The growth of SWCNTs almost stops after the initial 2 min, then, the mass increase of the samples mainly originates from the metal@CNP formation. Therefore, high‐purity SWCNTs (98.5 wt%) with few metal@CNPs can be available by 2 min CVD growth. Furthermore, CO2 oxidation of the SWCNTs is also investigated in a thermogravimetric reactor. The oxidation of graphene layers surrounding the metal NPs and the SWCNTs occurs during distinct temperature ranges, which is further demonstrated by the significant differences among their oxidation activation energies. Ultrahigh purity of SWNCT with a carbon content of 99.5 wt% can be available by a CO2‐assited purification method. The in situ study of the CVD growth and CO2 oxidation of SWCNTs provides the real time information on the working catalyst during reaction and the reactivity information of metal@CNPs and SWCNTs under an oxidizing atmosphere. The success for the preparation of high‐purity SWCNT lies in the efficient growth of SWCNTs with a low amount of nanocarbon impurities and partial oxidation of metal@CNPs by catalytic CO2 oxidation with proper operation parameters. 相似文献