Selective Formation of Metal Nanoparticles on the Sidewalls of Carbon Nanotubes

Pt and Au nanoparticles spontaneously form on the sidewalls of single-walled carbon nanotubes (SWNTs) and multiwall carbon nanotubes (MWNTs) in a selective manner. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies reveal that metal ions are first absorbed on the sidewalls of carbon nanotubes (CNTs) and then are reduced by ethanol. This mechanism is tentatively proposed and discussed.     

Covalent Surface Chemistry of Single‐Walled Carbon Nanotubes

In this review article, we explore covalent chemical strategies for the functionalization of carbon‐nanotube surfaces. In recent years, nanotubes have been treated as chemical reagents (be it inorganic or organic) in their own right. Indeed, from their inherent structure, one can view nanotubes as sterically bulky, π‐conjugated ligands, or conversely as electron‐deficient alkenes. Hence, herein we seek to understand, from a structural perspective, the breadth and types of reactions single‐walled nanotubes (SWNTs) can undergo in solution phase, not only at the ends and defect sites but also along the sidewalls. Controllable chemical functionalization suggests that the unique electronic and mechanical properties of SWNTs can be tailored in a determinable manner. Moreover, prevailing themes in nanotube functionalization have been involved with dissolution of tubes.     

过渡族金属硫化物纳米管结构研发现状

随着碳富勒烯和碳纳米管的发现,具有类似层状结构的纳米颗粒MoS2,由于片层状平面结构的不稳定,易形成封闭多面体笼状结构和管状结构.综述了过渡族金属硫化物MS2(M=W,Mo,Nb,Ta,Zr,Ti,Re,Hf)纳米管的合成方法、微观结构、生长机制及其潜在的性能和应用.     

微量氧对单壁碳纳米管生长的辅助催化作用研究

采用温控电弧炉,分别于He气氛和催化剂中加入不同量的氧,系统地研究了氧对纳米管形成的影响。TEM等研究分析表明,气氛中含有一定量的氧有利于氧化非晶碳促进纳米管的生长;催化剂中加入金属氧化物可以起到辅助催化的作用,减少产物中杂质含量,提高单壁碳纳米管的纯度。     

研究单壁碳纳米管杨氏模量的一种能量方法

本文利用能量方法研究了单壁碳纳米管(single-walled carbon nanotubes, SWCNT)的杨氏模量.文中,首先采用分子力学理论得出了受轴向载荷作用下单壁碳纳米管的总势能;然后通过总势能与相应薄圆柱壳的应变能比较,推导出了单壁碳纳米管杨氏模量的计算公式.另外,从一系列碳纳米管杨氏模量的计算发现,本文研究结果与现有研究结果比较一致.     

石英基底上定向单壁碳纳米管阵列可控生长

以铜为催化剂,甲烷为碳源,采用化学气相沉积法在石英单晶基底上生长定向单壁碳纳米管阵列,分别用扫描电子显微镜、原子力显微镜对其结构进行表征,研究了使用聚合物聚乙烯丙烯酸甲脂（PMMA）分散催化剂对碳纳米管密度和定向性的影响,利用PMMA分散催化剂能提高催化剂的活性,增加定向碳纳米管的密度,使催化剂形成规则的条状,能进一步提高其密度和定向性。采用微加工工艺做成器件,并利用半导体参数测试仪对器件进行了电学测试。     

HRTEM observations on composites of tin and tin dioxide nanoparticles dispersed on carbon nanotubes by single-atoms-to-clusters method

Nano-composites of tin and tin dioxide particles were synthesized on carbon nanotubes by the single-atoms-to-clusters (SAC) method, and their structures were investigated by high-resolution transmission electron microscopy. By changing the heat-treatment temperature during the SAC process, two different types of samples were obtained. The samples prepared around 450 K were aggregates of 2-4 nm-sized tin dioxide nanoparticles, and their size distributions on carbon nanotubes are in the range 20-40 nm. The other samples formed above 600 K had a core-shell structure of diameter 20-40 nm. The core and shell were made of tin single crystal and disordered oxidized tin, respectively. The thickness of the oxidized layers was ca. 4 nm.     

HRTEM observations on composites of tin and tin dioxide nanoparticles dispersed on carbon nanotubes by single-atoms-to-clusters method

Nano-composites of tin and tin dioxide particles were synthesized on carbon nanotubes by the single-atoms-to-clusters (SAC) method, and their structures were investigated by high-resolution transmission electron microscopy. By changing the heat-treatment temperature during the SAC process, two different types of samples were obtained. The samples prepared around 450 K were aggregates of 2–4 nm-sized tin dioxide nanoparticles, and their size distributions on carbon nanotubes are in the range 20–40 nm. The other samples formed above 600 K had a core–shell structure of diameter 20–40 nm. The core and shell were made of tin single crystal and disordered oxidized tin, respectively. The thickness of the oxidized layers was ca. 4 nm.     

金属对炭黑转化为洋葱状中空结构纳米碳的影响

研究了炭黑分别在 Fe、Co、Ni 三种金属化合物作用下的催化转化行为, 以期使炭黑质点中不连续的无规则小石墨片层重新组装、构筑成洋葱状中空结构纳米碳. 采用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)和Raman光谱分析表征了炭黑及其催化炭化产物的微观形貌和结构. 结果表明: 尽管三种金属催化剂均可通过溶碳-析出机制形成过渡态碳包覆纳米金属颗粒, 继而构筑成由准球形同心石墨壳层组合的洋葱状中空结构纳米碳, 但三种金属催化剂显示不同的催化效果, 终碳产物的形态和纯度差异较大, 其中以Fe 的催化效果最好.     

过渡金属氮化物TinNm小团簇结构中的定域键

Ti、N形成的小团簇TinNm,当n＋m≤4时,一般出现线形和平面构型;当n＋m=5或6时,TinNm团簇异构体既有线形结构,也有平面结构,还有少数立体结构。线形结构大多形成强弱交替的定域键。平面结构中Ti—N键,随着原子数的增加,逐渐从共价键向离子键过渡,Ti失去电子增多,N得到电子也增多。而立体构型中大多形成离域键,验证了Anderson理论。     

多壁碳纳米管功能化及其增韧环氧树脂的研究

采用混酸氧化多壁碳纳米管（MWCNTs），然后将其与过氧化丁二酸反应，接着对其进行酰胺功能化处理，并用功能化后的MWCNTs对环氧树脂（EP）进行增韧改性，研究了不同含量MWCNTs对EP力学性能的影响，探讨了其改性机理。研究结果表明，经过功能化处理，MWCNTs表面成功接上了一定数量的酰胺基团，将其加入到EP中可大幅度提高EP的冲击强度，在其用量为1．5wt％时，冲击强度提高了92%,SEM结果显示，加入MWCNTs后印由脆性断裂转变为韧性断裂。     

Research on the Relationship between Density of States and Conducting Properties of Single-walled Carbon Nanotubes

The analytical expression of the electronic density of states (DOS) for single-walled carbon nanotubes (SWNTs) has been derived on the basis of graphene approximation of the energy E(k) near the Fermi level EF. The distinctive properties of the DOS, the normalized differential conductivity and the current vs bias for SWNTs are deduced and analyzed theoretically. The singularities in the DOS (or in the normalized differential conductivity) predict that the jump structure of current (or conductance)--bias of SWNTs exists. All conclusions from the theoretical analysis are in well agreement with the experimental results of SWNT‘s electronic structure and electronic transport. In other words, the simple theoretical model in this paper can be applied to understand a range of spectroscopic and other measurement data related to the DOS of SWNTs.     

A Note on Statistical Strength of Carbon Nanotubes

This note aims to relate the measured strength statistics of individual carbon nanotubes (CNTs) to the physics of brittle fracture and the weakest link model. By approximating an arbitrary flaw size distribution with a segmented power law, an effort is made to extend applicability of the Weibull distribution to arbitrary flaw populations, which explains why the Weibull distribution fits the experimental data of CNTs and many other brittle materials, and why in other cases it is not so clear. A generalized Weibull distribution is proposed to account for all non-asymptotic cases. The published CNT testing data are analyzed, and finally a major issue present in existing interpretation of CNT bundle testing data is clarified.     

碳纳米管泛用合金晶粒细化剂的作用

综述了碳纳米管细化金属晶粒的研究现状,主要包括镁基、铝基、铅锡基、镍基、铁基等,并指出将碳纳米管加入镁、铝、铅、铁、镍基金属合金中都可以明显地细化这些合金材料的基体组织,同时阐述了目前假设的碳纳米管细化晶粒的机理:提供了较多优先形核的位置和阻碍晶粒的长大。