催化剂组分对制备单壁碳纳米管的影响

利用柠檬酸法制备出了Mo-Fe-MgO，Mo-Co-MgO和W-Co-MgO催化剂，在小型流化床中，以Ar气为载气，在1123 K下催化裂解CH₄来制备单壁碳纳米管(SWCNTs).利用透射电子显微镜和拉曼光谱方法研究了催化剂组分对SWCNTs制备的影响，并对SWCNTs的生长机理进行了探索，研究结果表明，柠檬酸法是一种制备负载型SWCNTs催化剂的有效方法，三种催化剂都能够得到质量较好的SWCNTs,在1123 K左右，SWCNTs在三种催化剂上的生长过程可能类似于“微液相模型”.催化剂的组分对SWCNTs的管径分布影响较小，不同催化剂所得到的SWCNTs在内部结构上存在一定的差异.催化剂中加入第二组分Mo和W能有效提高产物的碳产率. 关键词： 单壁碳纳米管 催化化学气相沉积法 生长机理 拉曼光谱     

乙醇做碳源Mo-Co/MgO做催化剂合成单壁碳纳米管

本文采用柠檬酸法制备Mo-Co/MgO催化剂, 在小型流化床中, 以Ar气为载气直接携带乙醇蒸汽进入反应器, 通过化学气相沉积（CCVD）技术来合成制备单壁碳纳米管（SWCNTs）。利用扫描电镜和拉曼光谱方法研究了催化剂组分比例和载气流量等对SWCNTs制备的影响。研究结果表明: 以乙醇做碳源, Mo1-Co10/MgO做催化剂, Ar气流量为150sccm时制备的单壁碳纳米管质量最佳。     

单壁碳纳米管吸附酞菁类有机物的研究

利用苯氧基酞菁修饰单壁碳纳米管,并利用透射电子显微镜、紫外可见吸收光谱、荧光光谱以及拉曼光谱进行了表征分析.在透射电镜下观察到结合物呈现糖葫芦状,吸附后吸收光谱以及荧光光谱中峰的强度明显下降说明单壁碳纳米管吸附了大量的苯氧基酞菁,通过拉曼光谱发现吸附后单壁碳纳米管的拉曼光谱中主要峰的位置向长波数方向移动,原因是单壁碳纳米管吸附苯氧基酞菁前后状态的改变导致的.     

碳纳米管的表面修饰及FTIR,Raman和XPS光谱表征

用红外、拉曼光谱、X射线光电子能谱（XPS）研究了水热条件下碳纳米管在不同氧化剂中的表面修饰过程。结果表明水热条件下可以成功地实现碳纳米管的表面修饰,而且,通过控制反应条件可以改变反应产物中官能团的种类和数量。     

修饰银电极上单壁碳纳米管的表面增强拉曼散射

本文采用修饰了银纳米颗粒的银电极作为基底,获得了高质量的单壁碳纳米管(SWCNTs)的表面增强拉曼散射(SERS)光谱。在1100~1500 cm-1范围内观测到了一组表征SWCNTs结构的新峰。修饰在银电极上的银纳米颗粒不仅可以保证SWCNTs在这一体系中吸附的紧密性,而且通过变面等离子体共振起到了电磁放大的作用。通过对银纳米颗粒修饰银电极表面SWCNTs的SERS光谱及其随电位变化的SERS光谱的研究,我们可以研究这一过程中的SERS机制。理论和实验结果表明,银纳米颗粒修饰银电极上单壁碳纳米管的SERS很有潜力成为一种检测单壁碳纳米管合成质量的新方法。     

一种高效的用含水乙醇制备单壁碳纳米管的方法

本文采用流化床反应器,利用MgO作为催化剂载体,以Mo和Fe为催化剂。让Ar气流携带含水的乙醇蒸汽进入反应器,通过化学气相沉积(CCVD)法合成了单壁碳纳米管(SWCNTs)。利用拉曼光谱和透射电镜(TEM)对所合成的单壁碳纳米管质量进行检测。实验结果表明无水乙醇中加入7%的水反应温度在950℃时,制备的单壁碳纳米管的质量最好而且管径分布非常均匀。     

单壁碳纳米管的场发射特性研究

利用场发射显微镜(FEM)和四极质谱计分别研究了经过热处理的单壁碳纳米管的场发射图像和热处理过程中样品脱附的残气质谱.当热处理温度达到1000℃左右时得到了单壁碳纳米管的场发射像,此像可能是顶端开口的单根(16,0)锯齿形单壁碳纳米管的具有原子可分辨的场发射图像.四极质谱分析结果表明,在此温度范围W针尖晶粒间隙中有O原子和C原子释放出来.它们对单壁碳纳米管顶端的修饰是我们能观察到这些碳纳米管场发射像的可能原因. 关键词： 单壁碳纳米管(SWCNTs) 场发射显微镜(FEM) 四极质谱     

单壁BN纳米管和碳纳米管物理吸附储氢性能的理论对比研究

采用巨正则蒙特卡罗方法(GCMC)研究了单壁氮化硼纳米管(SWBNNTs)和单壁碳纳米管(SWCNTs)的物理吸附储氢性能,主要对比研究了纳米管的管径、温度和手性对二者物理吸附储氢量的影响. 研究结果表明：在低温下,SWBNNTs的物理吸附储氢性能优于相应的SWCNTs;但是随着温度的升高,二者的物理吸附储氢性能差别越来越小,在常温下,SWBNNTs不具备有比SWCNTs更强的物理吸附储氢性能,而是和相同条件下的SWCNTs相差不大,只是在高压下的物理吸附储氢量稍稍大于SWCNTs,并给出了合理的理论解释 关键词： 巨正则蒙特卡罗方法(GCMC) 单壁氮化硼纳米管(SWBNNTs) 单壁碳纳米管(SWCNTs) 储氢     

聚甲基丙烯酸甲酯-功能化多壁碳纳米管的制备及性能

"以羧基多壁碳纳米管、甲基丙烯酸甲酯作为原料,过氧化苯甲酰作为引发剂,采用原位聚合法制备聚甲基丙烯酸甲酯-功能化多壁碳纳米管．利用投射电子显微镜、扫描电子显微镜、核磁共振、傅立叶转换红外光谱,热重分析和拉曼光谱对合成产物进行分析表征．结果表明,聚甲基丙烯酸甲酯共价接枝到羧基碳纳米管表面,羧基碳纳米管的含量影响合成产物的表观形态．核磁共振研究表明聚甲基丙烯酸甲酯-功能化多壁碳纳米管在氘代氯仿中有一定的溶解性．"     

单壁碳纳米管束针尖增强近场拉曼光谱探测实验研究

针尖增强近场拉曼光谱术是最近发展起来的光谱技术.金属探针在获得样品纳米局域表面形貌的同时,受激光激发,在针尖附近产生增强电磁场,得到与形貌位置精确对应的针尖增强局域拉曼光谱,形貌和光谱的结合实现了纳米局域的光谱指认.文章建立了一套针尖增强近场拉曼光谱测龋装置,并用此装置对电弧法合成的单壁碳纳米管进行了近场拉曼光谱探测.测量了直径为100 nm单壁碳纳米管束的针尖增强拉曼光谱,进一步得到至多3根单壁碳纳米管的近场拉曼光谱,实现了超衍射分辨光谱探测.通过与远场拉曼光谱比较发现,针尖增强近场拉曼光谱的增强因子大于230倍.实验证明,同时具有超衍射空间分辨和拉曼光谱信号增强能力的针尖增强近场拉曼光谱术将是纳米材料和纳米结构表征的一种重要方法.     

水分子链受限于单壁碳纳米管结构的密度泛函理论研究

本文采用第一性原理的密度泛函理论,主要以(6,6)Armchair型,(11,0)Zigzag型单壁碳纳米管为研究对象,研究了水分子链在碳纳米管内部吸附的稳定结构,以及结合能随其结构的变化.结果表明:当水分子链受限于碳纳米管内部时,引起碳纳米管直径收缩,这主要是由于水分子链与碳纳米管之间的氢键作用以及范德华弱相互作用所引起的.随着碳纳米管半径的增加,两种单体之间的结合能逐渐减小,但当碳纳米管半径增加至6.78时,其结合能又有所增加,这是由于在优化过程中,水分子链单体之间的氢键作用大于水分子链与碳纳米管之 关键词： 水分子链/单壁碳纳米管 密度泛函理论 结构稳定性     

直立在金膜表面的单壁碳纳米管的研究

用水溶胶体将单壁碳纳米管（ＳＷＣＮＴｓ）组装在晶态金膜表面,用扫描隧道显微镜（ＳＴＭ）研究了表面单壁碳纳米管直立于金膜表面,单根碳管的长度约在１０－１５ｎｍ之间。     

Equilibrium structures and flows of polar and nonpolar liquids in different carbon nanotubes

Molecular dynamics (MD) simulations of equilibrium structures and flows of polar water and nonpolar methane confined by single-walled carbon nanotubes (SWCNTs) with circular and square cross sections and bounding walls with regular graphene structure and random (amorphous) distribution of carbon atoms have been performed. The results of these simulations show that equilibrium structures of both confined liquids depend strongly on the shape of the cross section of SWCNTs, whereas the structure of their bounding walls has a minor influence on these structures. On contrary, the external pressure driven water and methane flows through above mentioned SWCNTs depend significantly on both the shape of their cross sections and the structure of their bounding walls.     

Compressive characteristics of single walled carbon nanotube with water interactions investigated by using molecular dynamics simulation

The elastic properties of single walled carbon nanotube (SWCNT) with surrounding water interactions are studied using molecular dynamics simulation technique. The compressive loading characteristic of carbon nanotubes (CNTs) in a fluidic medium such as water is critical for its role in determining the lifetime and stability of CNT based nano-fluidic devices. In this paper, we conducted a comprehensive analysis on the effect of geometry, chirality and density of encapsulated water on the elastic properties of SWCNT. Our studies show that defect density and distribution can strongly impact the compressive resistance of SWCNTs in water. Further studies were conducted on capped SWCNTs with varying densities of encapsulated water, which is necessary to understand the strength of CNT as a potential drug carrier. The results obtained from this paper will help determining the potential applications of CNTs in the field of nano-electromechanical systems (NEMS) such as nano-biological and nano-fluidic devices.     

光谱法研究水溶性羧基化碳纳米管与人血清白蛋白的相互作用

纳米材料与蛋白质等生物大分子的相互作用是纳米材料生物效应和安全性研究的重要基础。本实验利用荧光光谱、同步荧光光谱、圆二色谱(CD)等方法研究了四种结构特性不同的水溶性羧基化碳纳米管(long-SWCNTs-COOH,short-SWCNTs-COOH,DWCNTs-COOH,MWCNTs-COOH)与人血清白蛋白(human serum albumin, HSA)的相互作用。实验结果显示：四种水溶性羧基碳纳米管均能猝灭HSA的内源荧光,但猝灭能力有所不同,相同浓度下不同水溶性羧基化碳纳米管对HSA的荧光猝灭作用遵循如下规律：DWCNTs-COOH＜MWCNTs-COOH＜long-SWCTs-COOH＜short-SWCNTs-COOH;四种碳纳米管对HSA的同步荧光光谱影响表明,MWCNTs-COOH的作用位点更靠近色氨酸(Trp)残基,而DWCNTs-COOH的作用位点更靠近酪氨酸(Tyr)残基,而long-SWCNTs-COOH和short-SWCNTs-COOH对两种氨基酸残基的作用无明显差别;在碳纳米管作用下,HSA 的圆二色谱有微弱的变化,且与α-螺旋、β-折叠含量变化基本一致。结果表明,不同碳纳米管对HSA的荧光猝灭能力与它们的结构特性有关,两者作用过程中HSA构象基本不变,二级结构有微小变化,但无明显的剂量-效应关系。根据实验结果对可能的作用机制进行了讨论。     

Axisymmetric vibration of single-walled carbon nanotubes in water

A double shell-Stokes flow model is developed to study the axisymmetric vibration of single-walled carbon nanotubes (SWCNTs) immerged in water. In contrast to macroscopic solid-liquid system, a submerged SWCNT is coupled with surrounding water via the van der Waals interaction. It is shown that this unique feature substantially reduces viscous damping of the axisymmetric radial, longitudinal and torsional vibrations and significantly up-shifts the frequency of the radial vibration of an SWCNT. The study offers a theoretical explanation for the experimental observation and molecular dynamics simulations available in particular cases, and provides an efficient modelling tool and useful guidance for the study of the general dynamic behaviour of SWCNTs in a fluid.     

Role of thermal treatment on the structural behavior of the arc SWCNTs in the purification system process

The role of thermal oxidation before acid treatment and post high-temperature vacuum annealing of single walled carbon nanotube (SWCNTs) was studied by scanning electron microscopy, high-resolution transmission electron microscopy, thermogravimetric analyses and Raman spectroscopy. An efficient procedure is developed for the purification of SWCNTs with minimal damage to the walls and minimal modification in the length of the tubes. SWCNTs are employed in this study, are synthesized by arc-discharge method containing impurity of amorphous carbon, carbon shells, graphitic particles, metallic nanoparticles and metallic nanoparticles encapsulated inside the amorphous carbon or graphite.     

Co-effects of graphene oxide sheets and single wall carbon nanotubes on mechanical properties of cement

The enhancement of mechanical properties of cement composites by a carbon nanomaterial is an important topic. However, the co-effect of two (or more) carbon nanomaterials on the mechanical properties of cement has not been explored. In this paper, it was found that the mixture of graphene oxide (GO) sheets and single-walled carbon nanotubes (SWCNTs) exhibited an excellent co-effect, leading to 72.7% increase in bending strength of cement, which is much larger than the strength enhancements of 51.2% by GO and 26.3% by SWCNTs. Furthermore, it was demonstrated that the bending strength of cement composite materials with GO and SWCNTs is proportional to the sizes of crystal SiO₂ particles.     

Raman study of single wall carbon nanotube thin films treated by laser irradiation and dynamic and isothermal oxidation

The effect of visible and infrared irradiation on the structure of single wall carbon nanotubes (SWCNTs) is still an insufficiently resolved subject. In this paper, we report a detailed study of two types of SWCNT thin films treated by pulsed laser irradiation and dynamic and isothermal oxidation, respectively. Raman features of treated films were investigated by 532, 633 and 780 nm excitation lines, respectively. It was established that the 532 nm excitation laser line probes the surface of SWCNT films, while the two others probe the bulk of SWCNT films. It was found that during Raman measurements, one type of SWCNTs warms up significantly while the other type does not change temperature. Raman analysis of SWCNTs probed with 532 nm showed that effects of high power laser irradiation on two types of SWCNTs are completely different. Major effects are decomposition, debundlation and photooxidation. It was found that debundlation and removal of defective carbon are much more pronounced in one type of SWCNTs treated with dynamic oxidation. Dynamic oxidation affects mostly thinner SWCNTs that easily burn in air. The only significant effects of isothermal oxidation are the increase of defective amorphous carbon in the first type of SWCNTs and the decrease of D band and debundlation in the second type. Copyright © 2012 John Wiley & Sons, Ltd.