“纳米碳管薄膜新工艺技术研究”项目通过教育组织的科技成果鉴定

2002年1月5日，我校朱长纯教授等完成的“纳米碳管薄膜新工艺技术研究”通过了教育部组织的科技成果鉴定．“纳米碳管薄膜新工艺技术研究”项目是在纳米技术这一重大技术领域的背景下，对碳纳米管薄膜的生长和纯化工艺进行的深入研究，研制出了利用催化热解法生长和纯化碳纳米管薄膜及利用低压化学气象沉积法生长并优化碳纳米管薄膜的新工艺，为碳纳米管在多种领域的应用提供了技术手段，具有广阔的应用前景，达到世界领先水平．“纳米碳管薄膜新工艺技术研究”项目通过教育组织的科技成果鉴定     

准直纳米碳管的高效制备

给出了用阳极电弧在惰性气体(氦气、氩气)气氛下,蒸发含金属催化剂的石墨棒,高效制备宏观量的优质准直单壁纳米碳管的方法和条件以及纯化产物的方法.实验所得的网状和膜状产物分别含有63%和50%的准直单壁纳米碳管,阴极的棒状产物含有大量的多壁纳米碳管.准直单壁纳米碳管可用硝酸或高锰酸钾提纯多壁纳米碳管得到.纳米碳管管束的定向排列是由弧电场引起的磁致效应而形成的.     

全碳纳米管薄膜宏观电子器件的研究进展

近年来,宏观电子学受到了人们的广泛关注,它与大家熟知的微电子学互为补充但存在概念性差异。全碳纳米管薄膜器件具有优异的性能,尤其在柔性透明宏观电子器件方面具有明显的优势。研究人员发展了碳纳米管分离技术、薄膜制备技术和分层转移技术,并在此基础上实现了高性能全碳纳米管薄膜器件的构建。本文系统介绍了大面积碳纳米管薄膜的制备、碳纳米管之间的接触及其导电机制和全碳纳米管薄膜宏观电子器件的研究进展及应用,最后就该领域的研究现状及面临的主要问题进行了总结和展望。     

硅纳米孔柱阵列上低温无催化剂生长碳纳米管

采用化学气相沉积的方法在硅纳米孔柱阵列衬底上无催化剂生长出碳纳米管.分别在新制备的和制备后再在常温下自然氧化一周的硅纳米孔柱阵列衬底上进行无催化剂生长碳纳米管,结果发现新制备的硅纳米孔柱阵列表面没有碳纳米管长出,而自然氧化一周的硅纳米孔柱阵列表面有大量的碳纳米管出现.从硅纳米孔柱阵列的结构及表面氧化程度的不同加以分析,提出了无催化剂生长碳纳米管的生长机理,为在无金属催化剂条件下生长碳纳米管提供了一种新的方法.     

基于超级电容器的TiN@CNTF电极制备及性能研究

超级电容器因其独特的性能在便携式、可穿戴电子器件领域有着很大的应用潜力。目前对超级电容器的研究主要集中在对超级电容器电极材料的研究上。碳纳米管纤维具有电导率高、力学性能好、柔韧性高等优点,是超级电容器的理想电极材料。但是,碳纳米管纤维电容量的提升被其较小的比表面积所限制。通过在碳纳米管纤维表面生长三维阵列能够有效提高碳管纤维的比表面积,从而增大电容量。因此,采用水热法,在碳纳米管纤维表面成功生长TiO2纳米阵列,并通过氨气氮化获得了TiN@CNTF电极材料。采用三电极测试TiN@CNTF电极在Na2SO4溶液中的比电容达到215.5mF/cm2,有望作为一种柔性超级电容器的负极材料得到应用。     

Ag纳米颗粒修饰TiO2阵列薄膜的制备及其气敏性能研究

以钛酸丁酯为钛源,用水热法在透明导电衬底FTO上制备金红石相TiO2纳米阵列薄膜,以AgNO3为银源,用化学还原法制备尺寸可控的金属Ag纳米颗粒,将所制备的金属Ag颗粒修饰TiO2纳米阵列薄膜.研究Ag纳米颗粒的表面修饰对TiO2纳米阵列薄膜气敏性能的影响.实验结果表明,室温下,18nm金属Ag纳米颗粒修饰后的薄膜对氢气的灵敏度增加,响应和恢复时间减小,气敏性能明显优越于修饰前的薄膜.     

碳纳米管的化学镀铁钴和电磁参数研究

基于化学镀方法将CoB和FeB二元合金包覆在多壁碳纳米管模板上,制备了一种新的一维纳米复合材料.将JEM-2010透射电子显微镜显示多壁碳管的外径从13 nm增加到35 nm,能量色散X分析仪也表明碳管的表面镀覆了铁磁性纳米金属颗粒.用Angilent8722ES矢量网络分析仪在2～18 GHz测试了复合材料的动态电磁参数,在2 GHz时,铁包覆碳纳米管复合材料的复介电常数的实部ε′和虚部系数ε″分别为23.90和14.31,在2 GHz时复磁导率的实部μ′和虚部μ″分别为2.64和1.63,而钴包覆碳纳米管复合材料的ε′,ε″,μ′和μ″分别为12.00,2.04,1.28 和0.39.在低频处复合材料的磁导率和磁损耗相对于纯碳管有明显的增加.这种电磁特性可以应用于微波吸收材料.     

院校新闻

清华大学研制出碳纳米管薄膜扬声器中科院院士、清华大学物理系教授范守善,姜开利副研究员领导的科研小组的一项最新研究发现,碳纳米管薄膜在有音频电流通过时,会具有类似扬声器的功能。这些扬声器的厚度只有几十纳米,而且是透明、柔软和可伸长     

基于振动的亚微米阵列薄膜弹性参数辨识

亚微米阵列薄膜是以微/纳米尺寸的管、柱、弹簧等为基本单元,在同一平面内周期排列构筑的薄膜结构(厚度100 nm–1?m).亚微米阵列薄膜是人工合成的新型材料,需要依靠实验、理论和数值分析技术得到材料参数.由于亚微米阵列薄膜的几何微尺度,其固有频率达到MHz量级.本文提出了一种基于激光技术的非接触式振动测试方法,由振动特性确定了亚微米阵列薄膜弹性参数.     

北京大学化学与分子工程学院李彦课题组研究进展

李彦课题组采用原位聚合的方法制备出了碳纳米管阵列与聚丙烯酰胺水凝胶的复合薄膜。依赖于水凝胶的特性,这种薄膜具有良好的亲水性,能够快速吸收水分;同时碳纳米管的疏水性质以及其在复合材料中保持良好的阵列微观结构,使其具有很高的饱和水蒸气压,因此该复合薄膜又能迅速将吸     

采用超声组装与滚压工艺制备铝–碳纳米管复合材料

This study introduced a novel fabrication of aluminum–carbon nanotube (CNT) composites by employing bulk acoustic waves and accumulative roll bonding (ARB). In this method, CNT particles were aligned using ultrasonic standing wave in an aqueous media, and the arrayed particles were precipitated on the aluminum plate substrate. Then, the plates rolled on each other through the ARB process with four passes. Optical and scanning electron micrographs demonstrated the effective aligning of CNTs on the aluminum substrate with a negligible deviation of arrayed CNTs through the ARB process. The X-ray diffraction pattern of the developed composites showed no peaks for carbon and aluminum carbide. In addition, tensile tests showed that the longitudinal strength of the specimens processed with aligned CNTs was significantly greater than that of the specimens with common randomly dispersed particles. The proposed technique is beneficial for the fabrication of Al–CNT composites with directional mechanical strength.     

Application of Raman spectroscopy in carbon nanotube-based polymer composites

Raman spectroscopy has been widely used to identify the physical properties of carbon nanotubes (CNTs), and to assess their func-tionalization as well as orientation. Recently, Raman spectroscopy has become a powerful tool to characterize the interfacial properties between CNTs and polymer matrices. This review provides an overview of micro-Raman spectroscopy of CNTs and its application in studying CNT reinforced polymer composites. Based on the specific Raman band shifts relating to the mechanical deformation of CNTs, Raman scattering can be used to evaluate the interactions between the CNTs and the surrounding polymer in the composites, and to detect the phase transitions of the polymer, and investigate the local stress state as well as the Young’s modulus of the CNTs. Moreover, we also review the current progress of Raman spectroscopy in various CNT macroarchitectures (such as films, fibers as well as composite fibers). The microscale structural deformation of CNT macroarchitectures and strain transfer factors from macroscale architectures to microscale structures are inferred. Based on an in situ Raman-tensile test, we further predict the Young’s modulus of the CNT macroarchitectures and reveal the dominating factors affecting the mechanical performances of the CNT macroarchitectures     

硫辅助填充高压Fe5C2/Fe7C3单晶相的碳纳米管研究

硫可以用作生长促进剂制备具有不同形态的碳纳米结构, 例如: Y型和海胆状结构, 单壁碳纳米管(SWCNTs), 双壁碳纳米管薄膜等. 此外, 研究表明低浓度的硫和低气体流量可实现碳纳米管中高压Fe7C3和Fe5C2相晶体的填充. 然而, 碳纳米管中高压相的填充条件以及连续垂直取向的碳纳米管薄膜的合成和形貌控制的条件尚需进一步研究. 本文采用化学气相沉积(CVD),使用硫和二茂铁的混合物作为生长促进剂和碳源, 在氩(Ar)气环境中将Si/SiO2基底作为局部生长区域, 实现了在碳纳米管内填充碳化铁相, 并通过对所得碳结构进行详细表征, 揭示填充的碳化物相(Fe5C2和Fe7C3)之间可能存在结合, 这些结果在磁数据存储方面将有潜在应用.     

Oriented growth and assembly of zeolite crystals on substrates

The aligned array and thin film of zeolites and molecular sieves Possess a variety of potential applications in membrane separation and catalysis, chemical sensors, and microelectronic devices. There are two main synthesis methods for manufacturing the aligned arrays and thin films of zeolites and mo- lecular sieves, i.e. in situ hydrothermal reaction and self-assembly of crystal grains on substrates. Both of them have attracted much attention in the scientific community worldwide. A series of significant progress has been made in recent years. By the in situ hydrothermal synthesis, the oriented nucleation and growth of zeolite and molecular sieve crystals can be achieved by modifying the surface properties of substrstes or by changing the composition of synthesis solutions, leading to the formation of uni- formly oriented muIticrystal-aligned arrays or thin films. On the other hand, the crystal grains of zeo-lites and molecular sieves can be assembled onto the substrste surface in required orientation using different bondages, for instance, the microstructure in the array or thin film can be controlled. This review is going to summarize and comment the significant results and progress reported recently in manufacturing highly covered and uniformly aligned arrays or thin films of zeolites and molecular sieves. It involves （1） in situ growth of highly aligned zeolite arrays and thin films via embedding func-tional groups on the substrste surface, modifying the surface microstructure of substrates, as well as varying the composition of synthesis solutions; （2） assembly of zeolite and molecular sieve crystals on various substrates to form aligned arrays and thin films with full coverage by covalent, ionic, and in-termolecular coupling interactions between crystals and substrates; （3） coupling surface assembly with microcontact printing or photoetching technique to produce patterned zeolite arrays and thin films. Finally, the functionality and applications of zeolite arrays and thin films are briefly intr     

Structure characterization of melt drawn polyethylene ultrathin films

Highly oriented ultrathin polyethylene (PE) films were prepared by a melt-draw technique. Transmission electron microscopy study on the obtained ultrathin films indicates that the melt drawn PE thin films consist of highly oriented edge-on lamellae aligned perpendicular to the drawing direction. Electron diffraction confirms that the PE chains in crystal-line phase are highly oriented in film plane along the drawing direction, while only a random orientation of the crystallographic a-and b-axes can be described through electron diffraction. The IR results on the melt-drawn ultrathin PE films demonstrate that the PE molecular chains in both crystalline and amorphous phases of the melt drawn thin films are well oriented along the drawing direction. Moreover, the IR results indicate that in the crystalline phase, the crystallographic b-axis tend to lie in the thin film plane, while in the amorphous phase, the skeleton plane of some local chains prefers to parallel the film plane. The alignment of b-axis of PE crystals in ultrathin films originates from the fact that the b-axis is the fastest growth direction of the PE crystals.     

低噪声、宽谱响应的碳纳米管薄膜-石墨烯复合光探测器

采用高纯半导体碳纳米管薄膜和石墨烯构建复合结构光探测器, 研究其光电响应特性。结果表明, 在光照下, 顶层石墨烯中的光生载流子通过碳纳米管与石墨烯之间薄的非晶硅层, 隧穿至底层的碳纳米管薄膜中, 在非晶硅层两侧分别富集电子和空穴, 形成光致栅压(Photogating), 有效地改变了碳纳米管薄膜晶体管的电流。器件在可见光(633 nm)条件下得到响应度为83 mA/W, 并在近红外波段范围内仍保持好的光响应特性。由于石墨烯具有宽谱光吸收特性, 半导体碳纳米管薄膜晶体管具有小的暗电流, 碳纳米管–石墨烯复合光探测器发挥了两种材料的优势, 为今后高性能宽谱光电探测器的制备奠定了基础。     

Chemical,mechanical, and thermal expansion properties of a carbon nanotube-reinforced aluminum nanocomposite

In the present study, the chemical and mechanical properties and the thermal expansion of a carbon nanotube (CNT)-based crystalline nano-aluminum (nano Al) composite were reported. The properties of nanocomposites were tailored by incorporating CNTs into the nano Al matrix using a physical mixing method. The elastic moduli and the coefficient of thermal expansion (CTE) of the nanocomposites were also estimated to understand the effects of CNT reinforcement in the Al matrix. Microstructural characterization of the nanocomposite reveals that the CNTs are dispersed and embedded in the Al matrix. The experimental results indicate that the incorporation of CNTs into the nano Al matrix results in the increase in hardness and elastic modulus along with a concomitant decrease in the coefficient of thermal expansion. The hardness and elastic modulus of the nanocomposite increase by 21% and 20%, respectively, upon CNT addition. The CTE of CNT/Al nanocomposite decreases to 70% compared with that of nano Al.     

Large scale production of carbon nanotube arrays on the sphere surface from liquefied petroleum gas at low cost

Liquefied petroleum gas (LPG), a cheap industrial material, is used as carbon source to produce carbon nanotube (CNT) arrays on ceramic spherical surface on a large scale in the floating catalyst process. The ceramic spheres provide huge surface area and good mobility, leading to the mass production of CNT arrays continuously. The arrays obtained from the surface are of good alignment, and the purity is as high as 97.5%. With the decrease of the growth temperature, CNTs in the array form with small-diameter of about 13 nm can be obtained. Therefore, with the industrial fuel as carbon source and the ceramic sphere as substrate, CNT arrays can easily be produced on large scale at low cost.     

Substrate recognition strategy for botulinum neurotoxin serotype A

Clostridal neurotoxins (CNTs) are the causative agents of the neuroparalytic diseases botulism and tetanus. CNTs impair neuronal exocytosis through specific proteolysis of essential proteins called SNAREs. SNARE assembly into a low-energy ternary complex is believed to catalyse membrane fusion, precipitating neurotransmitter release; this process is attenuated in response to SNARE proteolysis. Site-specific SNARE hydrolysis is catalysed by the CNT light chains, a unique group of zinc-dependent endopeptidases. The means by which a CNT properly identifies and cleaves its target SNARE has been a subject of much speculation; it is thought to use one or more regions of enzyme-substrate interaction remote from the active site (exosites). Here we report the first structure of a CNT endopeptidase in complex with its target SNARE at a resolution of 2.1 A: botulinum neurotoxin serotype A (BoNT/A) protease bound to human SNAP-25. The structure, together with enzyme kinetic data, reveals an array of exosites that determine substrate specificity. Substrate orientation is similar to that of the general zinc-dependent metalloprotease thermolysin. We observe significant structural changes near the toxin's catalytic pocket upon substrate binding, probably serving to render the protease competent for catalysis. The novel structures of the substrate-recognition exosites could be used for designing inhibitors specific to BoNT/A.     

Sonication-assisted dispersion of carbon nanotubes in aqueous solutions of the anionic surfactant SDBS: The role of sonication energy

Sonication is a powerful technique to promote the dispersion of carbon nanotubes(CNTs) and enhance their solubility;this is necessary for CNT applications,especially in the biochemical and biomedical fields.In this study,batch experiments were conducted to evaluate the role of sonication energy on the dispersion of CNTs in the presence of a widely used anionic surfactant,sodium dodecylbenzene sulfonate(SDBS).It was observed that the concentration of dispersed CNTs in the SDBS solution depended on the sonication energy,but not the sonication time or output power of the sonicator alone.The amount of dispersed CNTs was positively correlated with the concentrations of SDBS and CNTs,and the length of the CNTs.The promotion of oxygen-containing functional groups on the dispersed CNTs was observed at relatively low sonication energies.The optimal energy,i.e.the minimum energy supplied by sonication to achieve a saturated suspension of dispersed CNTs in the SDBS solution,was CNT diameter-dependent,because of the larger vdW forces between tubes of smaller diameter.An exponential decay curve was constructed for the optimal energy values as a function of the outer CNT diameter,to assist in determining the energy needed to disperse CNTs.