钴/碳纳米管催化剂CVD法制备碳纳米管

以乙烯为碳源、多壁碳纳米管为载体负载钴作为催化剂,利用CVD法制备出了高质量的多壁碳纳米管.利用扫描电子显微镜(SEM)对催化剂的形貌进行了表征,利用透射电子显微镜(TEM)、X射线衍射仪(XRD)以及差热-热重(TG-DTA)方法对产物进行了表征.发现在最佳裂解温度770℃下制备的多壁碳纳米管直径分布均匀、曲率小、纯净、产率高,更重要的是不具有难处理的氧化物(如Al2O3)载体,充分体现了碳纳米管作为载体的优越性.     

Relation between Growth Parameters and Morphology of Vertically Aligned Fe-filled Carbon Nanotubes

Fe-filled multi-wall carbon nanotubes (MWNTs) were produced by pyrolysis of ferrocene in a dual furnace system. They grew vertically aligned on oxidized silicon substrates placed inside the reaction zone of a chemical vapor deposition reactor. A variation of the growth parameters has been performed in order to evaluate the possibility to control the Fe-filled nanotube growth process and thereby the nanotube- and the filling length, diameter and yield, and also the nanotube alignment. Electron microscopy studies show nanotubes with quite different morphologies. The relation between the aligned Fe-filled MWNTs growth and the most important growth parameters is discussed.     

碳纳米管增强复合材料的研究进展

介绍了CNTs的结构和性能,综述了CNTs在金属基复合材料、聚合物基复合材料和陶瓷基复合材料中的应用研究情况,在此基础上,分析了CNTs在复合材料制备过程中的纯化、分散、损伤和界面等问题,并展望了今后CNTs复合材料的发展趋势.     

分枝碳纳米管的制备及生长机理

分枝碳纳米管在微纳电子器件等领域具有十分广阔的应用前景。介绍了分枝碳纳米管的各种制备方法,探讨了分枝碳纳米管的不同生长机理,重点分析了影响分枝碳纳米管的形成及分叉的因素,对分枝碳纳米管的制备具有重要的指导意义。     

Carbon Nanotubes Based Devices and Sensors

The dimensionality of a system has a profound influence on its physical behavior, especially for nanostructured materials where at least one of the dimensions is less than 100 nm and, in many instances, the size is comparable with the size of many fundamental physical quantities. Carbon-based nanostructured materials exhibit unique mechanical, electrical, and optical characteristics that may result in many unique device designs. The materials are biocompatible, chemically inert, yet capable of altering electronic properties in presence of some chemical species, dimensionally compatible with bio-molecules, and have interesting electronic characteristics; hence, rendering them as potential chemical and biosensors. A recent heightened awareness of the potential for inadvertent or deliberate contamination of environment and food and agricultural products has made decentralized sensing an important issue for several federal agencies. Recent progress in nanostructured materials and its possible applications in chemical and biological sensors could have a significant impact on data collection, processing, and recognition. Our present and ongoing investigation is aimed towards evaluating the applications of carbon-based nanotubes, nanowires, and nanoporous materials in unique devices and sensors, based on its unique characteristics, morphological flexibility, and biocompatibility.     

One Step Synthesis and Growth Mechanism of Carbon Nanotubes

A simple one step,reproducible,synthesis route for carbon nanotubes was proposed.No external catalyst was used for the synthesis.These nanotubes were obtained after decomposition of acetone at 650 ℃ in a specially designed autoclave.The pressure generated due to decomposition of acetone played a vital role in the synthesis.The X-ray diffraction pattern and transmission electron microscopy of the sample showed that the diameter of nanotubes is in the range of 3—14 nm.The thermo gravimetric analysis showed 3%weight loss below500 ℃;the content of amorphous carbon is very less.The growth mechanism of CNTs was also proposed in the present paper.     

碳纳米管增强铜基复合材料的研究进展

高强高导铜基材料是一类有着广阔应用前景的材料,将碳纳米管作为增强相来制备铜基复合材料可以满足其对于强度和导电性的要求。制备出性能优良的复合材料的关键是解决碳纳米管的均匀分散及其与铜基体的界面结合问题。介绍了目前碳纳米管增强铜基复合材料的制备工艺及其所取得的成绩,并展望了将来的发展方向。     

碳纳米管的力学性能及聚合物/碳纳米管复合材料

综述了碳纳米管（CNTS）的制备方法、结构与力学性能的关系，介绍了近年来聚合物／碳纳米管复合材料的最新进展，对现有聚合物／碳纳米管复合材料的制备方法存在的主要问题进行了分析。     

基于原子力显微镜的碳纳米管焊接

在利用碳纳米管（CNT）制作纳米电子器件时,碳纳米管与金属电极的接触特性将决定器件性能.为此本文提出了一种利用原子力显微镜（AFM）进行碳纳米管焊接的新方法.仿真研究了探针电场的强度与分布,解释了焊接中电场产生的机理,进一步分析了偏压、探针-样品距离与探针悬臂梁偏转位移之间的关系;并通过这些优选的相关实验参数进行了焊接实验验证.实验结果表明,碳纳米管与电极间的接触电阻由2.86×106Ω减小至7.14×105Ω,并可实现碳纳米管在电极上的良好固定.     

Synthesis of Boron Nitride Microtubes and Formation of Boron Nitride Nanosheets

Boron nitride microtubes are synthesized in a dual zone quartz tube furnace at 1200°C with ammonia as a reaction atmosphere. Field emission scanning electron microscopy (FE-SEM) results show a unique cone-like morphology of the tubes with larger internal space and thin walls structure. The diameters of the tubes were found to be in the range of 1 to ～2 µm with the walls thickness estimated to be from 10 to 100 nm. XPS survey shows N 1 s and B 1 s peaks at 398.7 and 191 eV, respectively, that represent h-BN in the sample. Raman spectroscopy indicates a high-intensity peak at 1372.53 (cm^?1) that corresponds to the E_2g mode of h-BN. Along with the novel tubular morphology of boron nitride microtubes, the present work also explains a mechanism for the formation of boron nitride nanosheets (from boron nitride microtubes) found in the FE-SEM results of the current sample.     

单壁碳纳米管的研究进展

单壁碳纳米管是一种新型纳米材料,其制备方法有石墨电弧放电法、化学气相沉积法（又称催化裂解法）和激光蒸发法。化学气相沉积法是产业化生产单壁碳纳米管的有效方法。碳纳米管强度高、密度低,具有奇特的光学、电磁、热学、储氢性能等,广泛应用于现代科技中航空、航天、军事、医学等科学技术领域。     

CNTs/TiO2复合物制备及光催化性能研究

在不使用表面活性剂的情况下, 采用溶胶-凝胶法成功制备CNTs/TiO₂复合物, 利用XRD、TEM、HRTEM和SAED对样品的结构和形貌进行了表征。选取亚甲基蓝溶液为目标降解物, 利用紫外-可见(UV-Vis)分光光度计考察了CNTs/TiO₂复合物的光催化活性, 系统研究了CNTs掺杂量对催化降解效率的影响。实验结果表明: 经450℃煅烧, 锐钛矿相TiO₂通过C-O-Ti键均匀地涂覆在CNTs表面, TiO₂颗粒尺寸约16 nm。CNTs/TiO₂复合物光催化活性明显高于纯TiO₂, 当CNTs掺杂量为1wt%时, CNTs/TiO₂复合物对亚甲基蓝的催化降解效率最高, 比纯TiO₂提高11.7%。     

粉煤灰抑制ASR的机制

本文研究粉煤灰对ASR的抑制作用.测定了不同粉煤灰掺量砂浆棒膨胀率、水泥石中Ca(OH)2含量以及主要水化产物C-S-H凝胶的微观结构和化学组成,并对粉煤灰抑制ASR的机制进行探讨.结果表明:随粉煤灰掺量增加,其对ASR具有显著的抑制效果.水泥石中Ca(OH)2含量不断减少,二次反应生成大量低n(Ca)/n(Si)的C-S-H凝胶.随n(Ca)/n(Si)降低,C-S-H凝胶中固溶了大量的Al,凝胶的固碱能力增强,从而使混凝土孔溶液中的有效碱大大减少,减轻了ASR程度.凝胶的固碱能力增强除了因n(Ca)/n(Si)降低,使C-S-H凝胶的固碱能力增强之外.还可能因为Al3 代替Si4 形成[AlO4]5-四面体,由于Al3 比Si4 少一价,引起电价不平衡,系统带负电,因此碱离子更容易进入C-S-H凝胶中,减少了碱与活性集料反应的机会.     

钴的价态对Co/Mo/MgO催化剂制备碳纳米管的影响

用溶胶凝胶煅烧法制备的Co/Mo/MgO催化剂中,除了形成Mg（Co）MoO4固溶体,一部分Co元素随着煅烧温度的提高,从Co3O4转变为CoO。在不同钴价态的催化剂上,用CVD法制备了碳纳米管。X射线衍射、电子显微镜、拉曼光谱和TGA表征显示,单壁碳纳米管可能是在Co3O4上生长的,多壁碳纳米管可能是在Mg（Co）MoO4上生长的,而在此场合下CoO并不是制备碳纳米管的有效催化剂。     

碳纳米管填充金属Ag纳米线及其机理研究

通过湿化学法将金属Ag成功填入碳纳米管,填充物的形态为纳米线状.用浓硝酸通过沸点回流法对碳纳米管进行处理,处理后不但除掉了其表面的杂质,而且碳纳米管端帽打开并明显被切短.AgNO3溶液通过毛细作用进入开口后的碳纳米管中,在450℃用H2进行还原,还原后碳纳米管被Ag纳米线填充,Ag纳米线直径为20～40nm,长度100nm～10μm.通过透射电镜(TEM)和X射线衍射(XRD)分析研究了Ag纳米线的微观形态和结构.在实验基础上探讨了金属Ag纳米线的形成机理.     

螺旋形碳纳米管的制备表征及其生长机理的探讨

采用气凝胶与干凝胶两种催化剂载体通过化学气相淀积方法制备出螺旋状的碳纳米管.研究结果表明:气凝胶催化剂载体所制备出的螺旋碳纳米管和干凝胶载体所制备出的螺旋碳管相比较具有以下几个特点:(1)较好的石墨化程度,(2)较小的直径,(3)较好的螺旋形态,即较好的螺距一致性.分析结果认为气凝胶独特的介孔性质是导致气凝胶样品所制备的碳管具有以上特点的根本原因.另外,还提出催化剂颗粒周边上催化活性的各向异性将导致螺旋碳管的生长.     

纳米碳管制备的新进展

本文讨论了有关纳米碳管制备的方法及工艺要求 ,同时介绍了在纳米碳管制备上的新进展和发展趋势     

Low Temperature Growth of Vertically Aligned Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Method

Synthesis of carbon nanotubes (CNTs) below 600℃ using supporting catalyst chemical vapor deposition method was reported by many research groups.However,the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced.In this work,the effects of varying the preheating temperature on the synthesis of CNT were investigated.The reaction temperature was set at 570℃.The preheating set temperature was varied from 150 to 400℃ at 50℃ interval.Three O-ring shape heating mantels were used as heating source for the preheater.In situ monitoring device was used to observe the temperature profile in the reactor.Benzene and ferrocene were used as the carbon source and catalyst precursor,respectively.Vertically aligned CNTs were synthesized when the preheating temperature was set at 400℃.When the preheating temperature was increased up to 400℃,both the length and the alignment of CNTs produced were improved.     

碳纳米管表面化学镀Ni的研究

通过对镀Ni前碳纳米管的氧化、敏化和活化处理,在碳纳米管表面增加活化点,成功地在碳纳米管表面镀上一层金属Ni,并用TEM对镀Ni前后的碳纳米管进行了表征.研究表明,用强酸对碳纳米管氧化处理后,可在碳纳米管表面产生大量官能团,改善表面性能,有利于对碳纳米管进行敏化和活化处理.尽可能多的活化点将有利于金属Ni在碳纳米管表面沉积,从而获得连续的金属Ni镀层,提高化学镀的质量.     

热丝CVD金刚石薄膜制备及碳纳米管形核作用的研究

利用热丝化学气相沉积法 (HF CVD)进行了金刚石薄膜制备和碳纳米管形核作用的研究。获得了制备金刚石薄膜的优化工艺参数。利用碳纳米管作为形核前驱获得了高质量的金刚石薄膜 ,其沉积速率可达 2 5 μm/h ,晶粒生长完美 ,而且没有出现聚晶现象。研究了碳纳米管涂料质量对薄膜沉积特性的影响 ,并对其机理进行了初步探讨