碳纳米管宏观条带的原位制备

采用化学气相沉积法(CVD),以二甲苯为碳源,二茂铁为催化剂,在涂有SiO₂薄膜的不锈钢基底上,原位制备出了碳纳米管宏观条带。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了表征。结果显示：合成的碳纳米管条带宽度为20～100 μm,厚度10～30 μm,长度可达6 mm;条带由大量多壁碳纳米管沿轴向密实排列组成。对其形成机制进行了初步探讨。     

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.     

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.     

碳纳米管的最新制备技术及生长机理

结合笔者的工作综述了碳纳米管的制备技术及生长机理的最新研究进展，重点介绍了近两年来碳纳米管制备的进展情况，包括传统制备方法的改进（电弧放电法、化学气相沉积法和激光蒸发法）、新型制备技术、特殊结构的碳纳米管制备；同时探讨了碳纳米管的各种生长机理；最后提出了碳纳米管制备技术和生长机理的发展方向。     

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。     

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.     

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.     

碳纳米管阵列的气相沉积制备及场发射特性

运用酞菁铁热解法气相沉积制备了碳纳米管阵列.所得碳纳米管呈多壁结构.单根碳纳米管的平均直径约为25 nm，长度约4～5 μm，且具有很好的准直性.研究了碳纳米管阵列的平面场发射特性，相应的开启电压和阈值电压分别为1.28和2.3 V•μm－1，表明碳纳米管具有很强的场发射能力.利用场发射显微镜观察了碳纳米管阵列的场发射像，发现碳纳米管阵列的场发射主要集中在样品薄膜的边缘部位.这是由于碳纳米管密度过大而产生的屏蔽效应所致.     

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.     

Production of single-walled carbon nanotubes from methane over Co-Mo/MgO nanocatalyst:A comparative study of fixed and fluidized bed reactors

In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes(SWNTs)have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition(CCVD)of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.     

Highly selective synthesis of single-walled carbon nanotubes from methane in a coupled Downer-turbulent fluidized-bed reactor

For the synthesis of single-walled carbon nanotubes (SWCNTs) from CH₄ over a Fe/MgO catalyst, we proposed a coupled Downer-turbulent fluidized-bed (TFB) reactor to enhance the selectivity and yield (or production rate) of SWCNTs. By controlling a very short catalyst residence time (1–3 s) in the Downer, only part of Fe oxides can be reduced to form Fe nano particles (NPs) available for the growth of SWCNTs. The percentage of unreduced Fe oxides increased and the yield of SWCNTs decreased accordingly with the increase of catalyst feeding rate in Downer. SWCNTs were preferentially grown on the catalyst surface and inhibited the sintering of the Fe crystallites which would be formed thereafter in the downstream TFB, evidenced by TEM, Raman and TGA. The coupled Downer-turbulent fluidized-bed reactor technology allowed higher selectivity and higher production rate of SWCNTs as compared to TFB alone.     

Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler-Nordheim tunneling mechanism and current-voltage (/-V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be     

Methane chemical vapor deposition on transition metal/GaAs samples – a possible route to Haeckelite carbon nanotubes?

We present a systematic study of atmospheric chemical vapor deposition growth of carbon nanotubes (CNTs) on patterned, transition metal/GaAs samples employing methane as the carbon feedstock. Controlled CNT growth was found to occur from the exposed metal‐semiconductor interface, rather than from the metal or semiconductor surfaces themselves. A fast sample loading system allowed for a minimization of the exposure to high temperatures, thereby preventing excessive sample damage. The optimum growth temperature for CrNi/GaAs interfaces is 700 °C (at a methane flow rate of 700 sccm). Possible growth scenarios involving the Ni–As–Ga system and its interaction with C is discussed. Raman spectroscopy of the CNTs revealed the presence of pentagon–heptagon defects. Closer analysis of the spectra points towards a mixture of so‐called Haeckelite CNTs. Copyright © 2011 John Wiley & Sons, Ltd.     

含钴介孔分子筛催化热解乙醇制备纳米碳管

以CTAB为模板剂,硅酸钠、氯化钴为原料,通过水热法合成含钴介孔分子筛(Co-MCM-41)。以所合成的Co-MCM-41做催化剂,采用化学气相沉积(CVD)法催化热解乙醇制备纳米碳管。通过XRD、FT-IR、TEM、N2吸附-脱附和Raman光谱等分析手段对所合成的介孔分子筛和纳米碳管进行了表征。结果表明:合成的Co-MCM-41样品具有MCM-41的介孔结构,比表面积较大且介孔有序性较好。以所合成的含钴介孔分子筛催化热解乙醇制备出管径均匀、管壁较厚、顶端开口的多壁纳米碳管。     

催化剂对纳米聚团床法制备的纳米碳材料形貌的影响

 在纳米聚团床中用催化化学气相沉积法批量制备了碳纳米管，研\r\n究了过渡金属催化剂对碳纳米管形貌和产量的影响．实验结果表明，含\r\n铁催化剂的活性较低，产率较低，但产品质量较好；含镍催化剂的活性\r\n较高，产率较高，但产品质量较差；在钴催化剂作用下发现了一种新型\r\n的针状纳米碳材料．用含载体较少的铁催化剂可以得到纯度较高且微观\r\n结构较好的碳纳米管，但产率较低；不含任何载体的纯镍催化剂则不能\r\n得到碳纳米管．适宜的催化剂组成、催化剂活性点的均匀分布和裂解速\r\n度的控制等构成了纳米聚团床大批量制备碳纳米管技术的关键．     

The effect of localized lateral growth of multiwalled carbon nanotubes with ammonia plasma post‐treatment

We present horizontally‐oriented multiwalled carbon nanotubes (CNTs) grown by means of thermal chemical vapor deposition. The CNT is across the trenches of the catalytic metals on predefined Ti electrodes. The properties of the lateral multiwalled CNT, following post‐ammonia plasma treatment, are reported. Information about the ammonia plasma treated on the interface structure of CNT is obtained using X‐ray photoelectron spectroscopy. The experimental results show that upon exposure to ammonia, the electrical property of the CNT is found to increase. Copyright © 2012 John Wiley & Sons, Ltd.     

椅型碳纳米管电子结构与长度效应

采用PM3方法对含帽结构的三种(5,5)椅型有限长碳纳米管的构型和电子结构进行了系统研究，结果表明，随着管长度的增加，除了最高占据轨道(HOMO)和最低空轨道(LUMO)之间的能隙(Eg)出现周期性的变化外，纳米管端“表面”(管的末端和管帽)构型也出现周期振荡现象，通过研究同种类型纳米管三组不同的长度效应，发现属于同一组的纳米管具有相似的构型和电子结构变化规律，此外，研究表明纳米管帽的尺寸效应可以看成为一定长度管壁的简单延伸，揭示了含帽与不含帽纳米管电子结构之间的相似性。本文还对处在管末端以及管帽上的表面态及其化学反应性进行了探讨。     

Chemically grafting carbon nanotubes onto carbon fibers for enhancing interfacial strength in carbon fiber/HDPE composites

We propose a novel method to uniformly graft high‐density carbon nanotubes (CNTs) onto carbon fiber (CF) by using coupling agents. Coupling agents can supply much more active groups, which is beneficial for grafting high‐density CNTs onto CF surface. After CNT grafting treatment, there are still substantial amounts of reactive groups, which can further react with various types of molecules to meet different requirements. To create chemical bonding between CF and high‐density polyethylene, CF‐CNT was further grafted get reinforcement. The interfacial adhesion of the resulting composites showed a dramatic improvement.