碳纳米管的宏量制备及产业化

作为纳米材料的代表之一,碳纳米管因其独特的一维结构具备了优异的力学、电学、热学、光学和反应性能,使其在能源存储与转化、复合材料、多相催化、环境保护及生物医药等领域具有大量的应用潜力.本文总结了多种类型碳纳米管宏量制备的化学及工程原理,并对多壁碳纳米管、单壁碳纳米管、双壁碳纳米管、定向碳纳米管、超顺排碳纳米管、水平超长碳纳米管、掺杂碳纳米管、螺旋碳纳米管、碳纳米管结及碳纳米管/石墨烯杂化物的宏量制备方法进行了评述.同时,对碳纳米管产业化中新的工程问题,如工业标准、环境评估以及产业化进展进行了分析.目前,碳纳米管已经具有成千吨的产能,并广泛应用于锂离子电池电极、导电复合材料、汽车配件和体育用品等领域.尽管如此,高性能的碳纳米管的宏量制备及其配套产业化技术仍有待深入开发,产品需要进一步丰富、市场需要进一步拓展,以望形成大规模纳米产业,促进社会的可持续发展.     

分叉碳纳米管的催化生长

Branching carbon nanotubes were synthesized by pyrolysis of acetylene at 700℃ over oxygen-free copper and γ-Al₂O₃-supported Cu unitary or Cu/Fe binary catalysts. The morphologies of the as-grown products were charac-terized by transmission electron microscopy. The results indicated that the branching structures were closely related to the Cu component of the catalysts. We proposed that the special electronic structure (3d¹⁰4s¹) of Cu play the crucial role in the formation of the heptagon defects related to the branching structures.     

基于六元环生长机理高产制备碳纳米管

基于六元环生长机理,以苯为前驱物高产率地制备了多壁碳纳米管。通过调变及优化催化剂的组成和用量、苯通量、生长温度等参量,碳纳米管的最高产率可达859wt%。高分辨透射电子显微镜、扫描电子显微镜、热重-差热分析仪、X射线衍射等分析结果表明,本方法制得的碳纳米管产物的直径约20 nm,纯度高,具有良好的石墨化程度。     

碳纳米管透明导电薄膜的可控制备

碳纳米管具有优秀的导电性能、 透光性能和十分突出的柔性, 在柔性透明导电薄膜中有着良好的应用前景. 如何制备同时拥有良好导电性能和透光性能的碳纳米管薄膜是这一领域研究的核心问题. 本综述介绍了碳纳米管薄膜的制备方法, 并重点讨论了基于漂浮催化剂化学气相沉积法的碳纳米管薄膜的可控制备. 在生长过程中限制碳纳米管的团聚、 增加碳纳米管的长度、 降低杂质的含量是提高碳纳米管薄膜性能的主要策略.     

纳米CaCO3负载过渡金属CVD法制备多壁碳纳米管的研究

以纳米碳酸钙粉体为载体,用浸渍法制备了可用于化学气相沉积(CVD)法制备碳纳米管的高产率催化剂.应用FESEM,HRTEM,TEM,XRD和激光拉曼谱对产物进行了表征.结果表明,由于纳米碳酸钙具有较大的比表面积,可高密度地承载催化剂活性组分.在碳纳米管生长初期,处于缓慢分解状态的纳米碳酸钙才能有效地起到载体作用,且反应温度为700～750℃时,碳纳米管的产率较高.Fe-Co双金属催化剂在700℃,催化生长60min后,可增重10倍,而且产物中无定形碳含量极少.纳米碳酸钙载体易于提纯,用质量分数为30%的硝酸超声提纯粗产品1h,可使纯度提高到97%,且不破坏碳纳米管结构.     

Fe/MgO催化合成碳纳米管和氮掺杂碳纳米管

以MgO负载的Fe为催化剂、正己烷为碳源、乙二胺为氮源, 用催化化学气相沉积法合成了碳纳米管(CNTs)和氮掺杂碳纳米管(CNx). 通过还原焙烧的Mg/Fe水滑石(LDH)和Mg(NO3)2/Fe(NO3)3前驱体得到具有催化活性的Fe催化剂(Fe-LDH和Fe-Mg(NO3)2/Fe(NO3)3). 由这两种催化剂催化合成的CNTs都具有中空的管状结构. Fe-LDH催化合成的CNx具有明显的“竹节”状形貌, 而Fe-Mg(NO3)2/Fe(NO3)3催化合成的部分CNx的形貌与“竹节”状不同. 该CNx具有厚的管壁且在管壁的石墨层与层之间存在大量的空隙. Fe-LDH催化合成的CNx中氮摩尔分数为6.3%, 高于Fe-Mg(NO3)2/Fe(NO3)3催化合成CNx中的5.7%; 但后者具有更多的缺陷, 石墨化程度更加无序.     

定位生长法制备AFM单壁碳纳米管针尖

采用粘性胶状物作为生长单壁碳纳米管(SWNTs)的催化剂前驱体, 在原子力显微镜下驱动废旧的硅探针粘附该种胶状物,随后进行化学气相沉积(CVD), 实现了SWNTs在硅探针末端的定位生长, 成功地制备出了SWNT针尖. 对SWNTs及SWNT 针尖进行了表征, 并对针尖的稳定成像条件进行了分析. 结果表明, 针尖一般由5-10 nm 的SWNT 管束构成, 伸出长度仅为几百纳米, 受热振动影响较小, 无需后处理即可稳定地成像, 成像分辨率与新的硅探针相当.     

不同形貌碳纳米管的制备及其嵌锂性能研究

以乙炔作为反应气 ,用化学气相沉积法 (CVD)和模板法在不同温度 (60 0℃、70 0℃ )下制备了不同形貌的碳纳米管 ,并采用TEM ,HRTEM ,SEM ,XRD ,Raman和充放电实验方法研究其形貌、结构和电化学嵌锂性能 .结果表明 ,不同的制备方法及反应温度对碳纳米管的形貌、结构特征和电化学嵌锂性能均有明显的影响 .在制备的样品中 ,制备温度越低 ,样品的石墨化程度越差 ,可逆嵌锂容量相应越高     

多孔氧化铝模板催化制备定向碳纳米管阵列

Well-aligned open-ended multi-walled carbon nanotube (MWCNT) arrays were prepared via chemical vapor deposition (CVD) method in porous anodic aluminum oxide (AAO) templates without depositing any transition metals as catalyst. Effects of the CVD temperature and heat treatment were studied in detail.Well-aligned open-ended MWCNT arrays were obtained at the CVD temperature above 600 ℃; when CVD temperature is reduced to around 550 ℃, CNTs, CNFs and other structures existed at the same time; no CNTs or carbon nanofibres (CNFs) could be found as the CVD temperature is below 500 ℃, and only amorphous carbon in the porous AAO template was found. Experimental results showed that the AAO template is catalytic during the CVD process, and it has the following two effects: to catalyze thermal decomposition of acetylene and to catalyze conversion of carbon decomposed from acetylene into CNTs or CNFs. Heat treatment could improve the graphitization degree, but it might also introduce new defects.     

CVD法制备单壁碳纳米管的纯化与表征

针对CVD法合成的单壁碳纳米管的特点提出了较为有效的纯化方法，并对纯化后碳管的存在形式进行了表征.结果表明,CVD法制备的单壁碳纳米管中所含的载体和催化剂绝大部分可以通过盐酸除去.在表面活性剂溶液中超声分散碳纳米管,可以使管与无定形碳及石墨状碎片进行有效的剥离.空气加热氧化法和稀硝酸回流法可有效地去除碳杂质,稀硝酸回流可以在纯化的同时对管的末端及侧壁进行功能化.     

Fabrication, Characterization and Electrocatalysis of an Ordered Carbon Nanotube Electrode

A method for fabrication of ordered carbon nanotube (CNT) film,which was template-synthesized within the highly ordered pores of a commercially available alumina template membrane,modified glassy carbon(CNT/GC) electrode was established.The CNT/GC electrode showed excellent electrocatalytic activity toward dopamine electrochemical reaction without introducing any electrochemically active group into CNT film or activating any electrochemically active group into CNT film or activating the electrode electrochemically.DA undergoes ideal reversible electrochemical reaction on CNT/GC electrode at low scan rate(≤20mV/s) with an excellent reproducibility and stability.The CNT/GC electrode might be used in biosensors because the highly ordered CNT may present a steric effect on more efficient redox reactions of biomolecules.     

金属基底上碳纳米管束的大面积制备

采用化学气相沉积法(CVD)，以二甲苯为碳源，二茂铁为催化剂，以沉积Al膜过渡层的不锈钢为基底，经过HF处理后，大面积合成了一种碳纳米管束状结构。使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和拉曼光谱(Raman)对样品形貌和结构进行表征。结果显示：合成的碳纳米管束直径为15～25 μm，长度超过500 μm，每根管束由大量直径为30～80 nm的多壁碳纳米管组成，这些碳纳米管沿管束轴线方向密实排列并相互缠绕，预示着具有较强的机械强度。结合实验对其形成机制进行了初步探讨。     

大面积N-掺杂定向碳纳米管阵列的制备与表征

采用无模板的化学气相沉积(chemical vapour deposition，CVD)法，以二甲苯和乙二胺为反应物，二茂铁为催化剂，以石英玻璃为衬底，制备了大面积、垂直于石英衬底生长、掺杂N的定向碳纳米管阵列。扫描电镜检测表明制备的定向碳纳米管阵列具有很好的定向性，而且管身平直。高分辨透射电镜的检测表明制备的碳纳米管具有较好的石墨化程度和较高的纯度，首次在碳纳米管内腔中发现了原位生长的“类富勒烯”结构。拉曼光谱的检测表明制备的定向碳纳米管阵列中含有大量的单壁碳纳米管。X射线光电子能谱检测表明N原子成功地被掺进了碳纳米管中，而且N原子的百分比随着碳源中N原子浓度的增加而增加，当碳源中n_C∶n_N比为1∶1的时候，在掺杂的碳纳米管中N原子的物质的量分数可以达到2.51%。     

联吡啶四唑铜(II)配合物的原位合成、结构及性质

采用水热合成法,通过配体5,5'-二氰基-3,3'-联吡啶和叠氮化钠在路易斯酸CuSO₄的作用下,得到了一种新型的金属有机铜四唑配合物。 X射线单晶衍射结构表明,该化合物属于四方晶系,P4/ncc空间群。它是由吡啶环中的N原子连接形成的无限延展的二维网状结构;硫酸根阴离子位于中心金属周围,且高度无序的硫酸根离子很有可能在低温下变成有序,从而引起结构相变。该化合物的堆积图形状类似一个蝴蝶发卡。 其高含氮结构可作为潜在的高含能材料。     

Fabrication of Bismuth/Multi-walled Carbon Nanotube Composite Modified Glassy Carbon Electrode for Determination of Cobalt

A bismuth/multi‐walled carbon nanotube (Bi/MWNT) composite modified electrode for determination of cobalt by differential pulse adsorptive cathodic stripping voltammetry is described. The electrode is fabricated by potentiostatic pre‐plating bismuth film on an MWNT modified glassy carbon (GC) electrode. The Bi/MWNT composite modified electrode exhibits enhanced sensitivity for cobalt detection as compared with the bare GC, MWNT modified and bismuth film electrodes. Numerous key experimental parameters have been examined for optimum analytical performance of the proposed electrode. With an adsorptive accumulation of the Co(II)‐dimethylglyoxime complex at ?0.8 V for 200 s, the reduction peak current is proportional to the concentration of cobalt in the range of 4.0×10^?10?1.0×10^?7 mol/L with a lower detection limit of 8.1×10^?11 mol/L. The proposed method has been applied successfully to cobalt determination in seawater and lake water samples.     

Modeling of Hierarchical Morphology of Carbon Nanotube Bundles in Polymer Composites

The morphological features of carbon nanotube (CNT) polymer composites and their influence on the effective modulus are evaluated. The considered features include bundle formation from the helical sub‐bundles made of individual CNTs. The formation of bundles is considered as a result of agglomeration of individual nanotubes above and below onset of percolation and is related to electrical conductivity. The proposed geometrical model yields a bundle diameter that agrees closely with that of the experimentally measured by voltage‐contrast method and scanning electron microscopy analysis of polyimide nanocomposites. The proposed micromechanical analytical model includes the helical structure of a bundle and provides close agreement of the effective Young's modulus of nanocomposite over a wide range of CNT content. It is shown that considering the helical structure of CNT bundles and its effect on bundle modulus is vital for predicting the effective modulus of CNT‐polymer nanocomposite.

     

碳纳米管含量对炭炭复合材料组织及力学性能的影响

炭纤维上原位合成了均匀生长且具有伸张形貌的碳纳米管,借助化学气相渗透制备了碳纳米管增强的炭炭复合材料,研究了不同含量的碳纳米管对炭炭复合材料组织和力学性能的影响。结果表明：炭纤维上生长碳纳米管改变了热解炭的沉积行为,诱导了各向同性热解炭的生成,且随着碳纳米管含量的增加,各向同性热解炭的厚度增加,但是复合材料的d002值却明显降低。微量的碳纳米管即可显著提高复合材料的力学强度,随着其含量的增加,复合材料的力学强度和模量迅速提高,但材料的断裂行为却急剧恶化,断裂模式由最初的假塑性断裂转变为脆性断裂。     

石墨烯/碳纳米管复合薄膜的制备进展

石墨烯/碳纳米管复合材料具有石墨烯和碳纳米管的共同特性,它弥补了石墨烯不连续和碳纳米管网存在间隙这两方面缺点。 本文探讨了石墨烯/碳纳米管复合薄膜的制备新进展,阐述了利用自组装合成、非原位合成以及非化学合成等方法制备厚度薄、强度高和比电容高等特点的石墨烯/碳纳米管复合薄膜的方法,对石墨烯/碳纳米管复合薄膜在传感器、锂电池和超级电容器等方面的应用前景进行了展望。     

Preparation of Amino-functionalized Multiwall Carbon Nanotube/Gold Nanoparticle Composites

Multiwall carbon nanotubes (MWNT) were modified orderly with carboxyl groups and amino groups. The MWNT/gold nanoparticle composites were formed when the amino‐functionalized MWNT was interacted with gold colloids. The functionalized MWNT was characterized using Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The amino‐functionalized MWNT allows further attaching gold nanoparticles through electrostatic interaction between the negatively charged gold nanoparticles and amino groups on the surface of the MWNT. The composite of gold nanoprticles and amino‐functionalized MWNT was characterized by transmission electron microscopy. This method decorating carbon nanotubes can be used to identify the location of functional groups, i.e. defect sites on carbon nanotubes.