等离子体科学和技术（NSF / DOE伙伴关系，这项工作是支持NSF批准号:CBET - 0853777和能源部批准号:DE - SC0001169），STTR第一期工程（NSF STTR期我No.1010133）。作者要感谢PPPL异地聚变能源科学办公室支持支持弧实验的研究计划。

1。阳极制备<ol><li>规模的镍粉（99.8％，300目）和钇粉（99.9％，40目）按4.2:1作为催化剂粉末的摩尔电台。 </li><li>混合石墨粉末的催化剂粉末（99.9995％，200目），非常好。填充到中空石墨棒（外直径5毫米，2.5毫米内径和75毫米的长度）牢牢的混合粉。确保总摩尔电台的C:倪:在阳极棒Ÿ是94.8:4.2:1，这是最佳比例合成单壁碳纳米管9。 </li><li>安装阴极杆（纯石墨，直径13毫米）和内圆柱腔的填充阳极棒（不锈钢，直径为152毫米和254毫米的长度）。调整阴极和阳极之间的差距约3毫米的距离。 </li></ol> 2。基板安装<ol><li>将长方体内室在距离约25毫米的极间轴永磁（25毫米× 25毫米× 100毫米）。超高温的铝镍钴磁铁在实验中，有650克的重量。使用时，极间的差距是关于H = 75毫米（ 图1a）由永久磁铁的底部的距离放置的配置。 </li><li>剪下的0.3毫米厚度25毫米的钼板（99.95％）× 100毫米的长方形。取出丙酮和乙醇超声50％的幅度，150 W的输出功率和40 kHz的频率为30分钟的超声波dismembrator的表面污染。 </li><li>安装附加永磁一侧的钼板材，电极转向这一面。 </li><li>极间的差距由高斯计测量磁场。保持电极之间的磁场平均约为0.06 T. </li></ol> 3。电弧等离子体点火<ol><li>泵圆柱腔压力小于10 -1托真空，然后填充氦气（99.995％）至500托。 </li><li>电弧电极连接直流weldi吴电源和成立约75答:电弧电流电源</li><li>记录的电弧电流，电弧电压和压力后的实验分析室的实时值。 </li><li>启动电弧同时由两个数码相机的权利和前视口中的视频。 1弧秒后开始的快照如图1b所示（右视口）和图1d（前视口）。 </li><li>运行15秒的弧线。通过自然对流降温室至少20分钟。 </li></ol> 4。合成后的分析和表征<ol><li>使用镊子撕下从表面钼表是针对电弧等离子体喷射沉积片状。另一个样品是采自阴极黑领。扫描电子显微镜下观察沉积片状双方的形态（加速电压为30千伏是）。 </li><li>关于样品制备<html> TEM分析，薄膜样品，获得铸造暂停甲醇 - 分散SWCNT溶液后60分钟使用50％的超声振幅超声波dismembrator的超声​​下降。 JEOL透射电镜下观察薄膜的甲醇溶液挥发后的100千伏的电压形态。对于样品中的兴趣地位，可与CCD相机长50厘米，与透射电镜电子衍射。 </li><li>拉曼光谱是基于一个200兆瓦的LEXEL 3000氩离子激光器（可调的单行输出），全息光学，0.5米光谱仪和液氮冷却的CCD探测器的微拉曼系统;波长为514纳米，它对应于2.33 eV的能量。拉曼光谱测量覆盖100厘米-1至3100 cm - 1的范围，并进行石墨薄片表面上。 </li></ol> 5。代表性的成果"&gt;视频快照，同时从分庭的权利和前视口中获得如图1b所示，为H D = 75毫米。这些照片反映了外部磁场的存在电弧等离子体柱的轴对称弧柱比较显著扰动观察到的情况下没有一个磁场10。 图2A和2B显示阴极无磁场的领子和透射电子显微镜下的B = 0.06特斯拉的磁场，分别收集的单壁碳纳米管和催化剂颗粒的典型形态。由此可以看出磁场单壁碳纳米管是紧密堆积成捆，直径范围从2至20纳米，由于个人单壁碳纳米管之间的相互作用的范德华的。相比较而言，没有磁场的单壁碳纳米管束的直径较大和较大的个体的直径，这与拉曼光谱的分析是一致的。此外，磁场CA在与图2a和图2b所示的纯度较高的单壁碳纳米管的n个结果。 最有趣的磁场影响石墨薄片可以从表面沉积片，这是钼板在同一进程中密切获得。图2C和 2D显示的石墨薄片的SEM和TEM图像以及数层石墨的位置采取样本获得相当于电弧等离子体喉。 图2d中的插图显示的电子衍射图案与石墨相关联。六角形点电子衍射呈现有序的晶体结构的证据。 拉曼光谱是一个强大的工具石墨片和单壁碳纳米管的特性。在石墨观察到典型的峰〜1600厘米-1和2700厘米-1分别为G和2D峰，激发波长为514纳米。在G峰源于在平面上可观察到的所有SP2碳材料的振动。 2D峰是一个二阶的D峰，但即使在非无序系统，由于第四阶声子动量交换双共振过程。它起着至关重要的作用在石墨表征。强度我（2D）/我（G）是单层石墨约4和后续图层此外下降，从而有可能估计石墨层的厚度。11图 3表示，我的价值（ 2D） /我（G）是1左右，可少层石墨的证据。可用于识别通过在径向方向的C原子的相干振动频率的碳纳米管直径的径向呼吸模（RBM）的120和350厘米-1拉曼光谱之间。之间的频率和单壁碳纳米管直径的实验关系RBM的ω= A / D T + B，其中参数Øf一个和b等于234和10厘米-1，分别形成了典型的单壁碳纳米管束。从图3中，没有磁场的单壁碳纳米管RBM的频率是163.8和215.2 厘米 -1，相应的平均个人的单壁碳纳米管直径为1.52和1.14 nm，分别。 <img alt="图1。" src="/files/ftp_upload/3455/3455fig1.jpg" /> 图1。论坛经济部长会议4.2软件模拟的磁场分布（a），电弧等离子体喷射的照片从右边的视口（B），电极的位置和方向的磁场时，极间的差距是定位的差距示意图约75毫米以上的永久磁铁（C）的底部，以及电弧等离子体喷射从前面的视口（D）的照片。 <img alt="图2。" src="/files/ftp_upload/3455/3455fig2.jpg" /> 图2代表TEM图像合成。（一）无磁场的单壁碳纳米管束和单壁碳纳米管束与磁场（B），典型的磁场（C），和TEM图像与磁场的石墨合成的石墨薄片的SEM图像。插图是选定区域的石墨晶体结构的电子衍射花样。 <img alt="图3。" src="/files/ftp_upload/3455/3455fig3.jpg" /> 图3在100至3100厘米-1范围内的磁场与样品的拉曼光谱。插图:没有RBM的频率周围磁场的样品的拉曼光谱。 <img alt="图4。" src="/files/ftp_upload/3455/3455fig4.jpg" /> 图4纳米结构的生长地区和碳和镍60答:请注意，碳和镍电极上的左，右右手边所示的密度，在同一地区并存的弧数密度。

<ol>
	<li>Dai, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+transport+properties+and+field+effect+transistors+of+carbon+nanotubes.">Electrical transport properties and field effect transistors of carbon nanotubes.</a> Nano. 1, 1-13 (2006).</li><li>Lai, K. W. C., Xi, N., Fung, C. K. M., Chen, H. Z., Tarn, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+the+band+gap+of+carbon+nanotube+for+infrared+sensors.">Engineering the band gap of carbon nanotube for infrared sensors.</a> Applied Physics Letters. 95, 221107-221107 (2009).</li><li>Gabor, N. M., Zhong, Z. H., Bosnick, K., Park, J., McEuen, P. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extremely+Efficient+Multiple+Electron-Hole+Pair+Generation+in+Carbon+Nanotube+Photodiodes.">Extremely Efficient Multiple Electron-Hole Pair Generation in Carbon Nanotube Photodiodes.</a> Science. 325, 1367-1371 (2009).</li><li>Liu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+storage+in+single-walled+carbon+nanotubes+at+room+temperature.">Hydrogen storage in single-walled carbon nanotubes at room temperature.</a> Science. 286, 1127-1129 (1999).</li><li>Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic-field-enhanced+synthesis+of+single-wall+carbon+nanotubes+in+arc+discharge.">Magnetic-field-enhanced synthesis of single-wall carbon nanotubes in arc discharge.</a> Journal of Applied Physics. 103, 094318-094318 (2008).</li><li>Li, J., Volotskova, O., Shashurin, A., Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+Diameter+Distribution+of+Catalyst+Nanoparticles+in+Arc+Discharge.">Controlling Diameter Distribution of Catalyst Nanoparticles in Arc Discharge.</a> Journal of Nanoscience and Nanotechnology. 11, 10047-10052 (2011).</li><li>Volotskova, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tailored+Distribution+of+Single-Wall+Carbon+Nanotubes+from+Arc+Plasma+Synthesis+Using+Magnetic+Fields.">Tailored Distribution of Single-Wall Carbon Nanotubes from Arc Plasma Synthesis Using Magnetic Fields.</a> Acs. Nano. 4, 5187-5192 (2010).</li><li>Volotskova, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-step+synthesis+and+magnetic+separation+of+graphene+and+carbon+nanotubes+in+arc+discharge+plasmas.">Single-step synthesis and magnetic separation of graphene and carbon nanotubes in arc discharge plasmas.</a> Nanoscale. 2, 2281-2285 (2010).</li><li>Farhat, S., Scott, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+the+arc+process+modeling+for+fullerene+and+nanotube+production.">Review of the arc process modeling for fullerene and nanotube production.</a> Journal of Nanoscience and Nanotechnology. 6, 1189-1210 (2006).</li><li>Keidar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increasing+the+length+of+single-wall+carbon+nanotubes+in+a+magnetically+enhanced+arc+discharge.">Increasing the length of single-wall carbon nanotubes in a magnetically enhanced arc discharge.</a> Applied Physics Letters. 92, 043129-043129 (2008).</li><li>Ferrari, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raman+spectrum+of+graphene+and+graphene+layers.">Raman spectrum of graphene and graphene layers.</a> Physical Review Letters. 97, 187401-187401 (2006).</li></ol>

我们什么都没有透露。

在图1b和 1d所示的关于H = 75毫米永磁底部的距离放置的情况下，极间的差距，视频快照，应该指出，改变磁铁的位置（我们测试的磁铁移位沿Z轴和转动的磁铁）的结果偏离弧对应的J × B 力方向如图1c所示，在x方向的喷流。有人还指出，电弧等离子体柱的几何形状没有改变，从阳极去除镍催化剂。这意味着，磁场对镍催化剂颗粒运动的影响，不影响整体几何等离子体柱。?...

特定的试剂和设备表: <table border="1"><tbody><tr><th>试剂名称</th><th>公司</th><th>目录编号</th><th>评论（可选） </th></tr><tr><td>甲醇</td><td> Acros Organics公司</td><td> 423950010 </td><td></td></tr><tr><td>镍粉</td><td>阿法埃莎</td><td> 10581 </td><td></td></tr><tr><td>钇粉末</td><td> Acros Organics公司</td><td> 318060050 </td><td></td></tr><tr><td>石墨粉末</td><td>阿法埃莎</td><td> 40799 </td><td></td></tr><tr><td>中空石墨棒</td><td>土星工业</td><td> POCO的EDM 3 </td><td></td></tr><tr><td>永磁</td><td>麦克马斯特 - 卡尔</td><td> 57315K51 </td><td></td></tr><tr><td>钼表</td><td> Dingqi科学。高科技。 </td><td> 080504-11 </td><td></td&gt; </tr><tr><td>超声波 dismembrator </td><td> Fisher Scientific则</td><td>型号150T </td><td></td></tr><tr><td>霍尔效应磁强计</td><td>大赦国际</td><td>型号100 </td><td></td></tr><tr><td>焊接电源</td><td>米勒电器</td><td>黄金之星600SS </td><td></td></tr><tr><td>真空泵</td><td> J / B </td><td> DV - 85N </td><td></td></tr><tr><td>教育统筹局局长</td><td>蔡司</td><td> LEO 1430VP </td><td></td></tr><tr><td>透射电镜</td><td> JEOL </td><td> 1200 EX </td><td></td></tr><tr><td>拉曼</td><td>堀场</td><td> HR800 </td><td></td></tr></tbody></table>

simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma

如单壁碳纳米管（SWCNT）和石墨的碳纳米结构吸引蜂拥而至时下由于他们非常有前途的应用分子传感器，场效应晶体管，超薄，灵活的电子设备1-4学者的兴趣。阳极弧放电的阳极材料的侵蚀支持是最实际和最有效的方法之一，它可以提供特定的非平衡过程和碳材料的大量涌入，在相对较高的温度发展中国家的结构，因此，作为合成产品有一些结构上的缺陷和更好的结晶。 为了进一步提高电弧放电合成碳纳米结构的可控性和灵活性，磁场可以被应用在合成过程中根据电弧等离子体的强磁场的反应。事实证明，磁增强弧dischARGE可以增加5的单壁碳纳米管的平均长度，狭窄的金属催化剂颗粒和碳纳米管 6的直径分布，并改变金属的比例和半导体碳纳米管，以及导致石墨合成8。 此外，它是值得的备注，当我们引进与正常的电弧电流的组件非均匀磁场，洛伦兹力J × B的方向沿可以产生等离子体喷射，使碳离子颗粒有效地提供和热通量的样本。因此，大型石墨片和高纯度的单壁碳纳米管，同时产生这种新的磁增强阳极弧方法。电弧成像，扫描电子显微镜（SEM），透射电子显微镜（TEM）和拉曼光谱来分析碳纳米结构的表征。这些结果表明广泛的机会来操作，通过控制电弧条件产生的等离子体中的纳米结构的特性。

Watch this Scientific Journal Video about Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma at JoVE.com

Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

阳极电弧放电合成各种碳纳米结构的最实际和最有效的方法之一。为了提高电弧的可控性和灵活性，非均匀磁场被引入大型石墨片和高纯度的单壁碳纳米管的过程中一步合成。

同时合成单壁碳纳米管和石墨在电弧等离子体磁增强

Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very ...

simultaneous-synthesis-single-walled-carbon-nanotubes-graphene

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

15.2K 次观看.  The George Washington University. 阳极电弧放电合成各种碳纳米结构的最实际和最有效的方法之一。为了提高电弧的可控性和灵活性，非均匀磁场被引入大型石墨片和高纯度的单壁碳纳米管的过程中一步合成。

视频: Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

制备，致密，副本三维碳纳米管微结构成型

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

科研

工程学

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene&#8217;s charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene&#39;s electronic structure in the presence of a charged impurity.&#160;The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene&#8217;s electronic properties.1-8 Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge2 and/or molecular5 states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies.2-5 These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices.

This paper details the fabrication process of a gate-tunable graphene device, decorated with Coulomb impurities for scanning tunneling microscopy studies. Mapping the spatially dependent electronic structure of graphene in the presence of charged impurities unveils the unique behavior of its relativistic charge carriers in response to a local Coulomb potential.

对于扫描隧道显微学与库仑杂质制造门可调谐石墨烯器件

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees ...

Preparation and Evaluation of Hybrid Composites of Chemical Fuel and Multi-walled Carbon Nanotubes in the Study of Thermopower Waves

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs along the interface between the fuel and core materials. Simultaneously, dynamic changes in thermal and chemical potentials across the micro/nanostructured materials result in concomitant electrical energy generation induced by charge transfer in the form of a high-output voltage pulse. We demonstrate the entire procedure of a thermopower wave experiment, from synthesis to evaluation. Thermal chemical vapor deposition and the wet impregnation process are respectively employed for the synthesis of a multi-walled carbon nanotube array and a hybrid composite of picric acid/sodium azide/multi-walled carbon nanotubes. The prepared hybrid composites are used to fabricate a thermopower wave generator with connecting electrodes. The combustion of the hybrid composite is initiated by laser heating or Joule-heating, and the corresponding combustion propagation, direct electrical energy generation, and real-time temperature changes are measured using a high-speed microscopy system, an oscilloscope, and an optical pyrometer, respectively. Furthermore, the crucial strategies to be adopted in the synthesis of hybrid composite and initiation of their combustion that enhance the overall thermopower wave energy transfer are proposed.

A protocol for conducting thermopower wave experiments is presented. The synthesis of hybrid composites of a chemical fuel and micro/nanostructured material, manufacturing of a thermopower wave generator, and methods for measuring the corresponding physical phenomena are described.

化学燃料和多壁碳纳米管的混杂复合材料的热电波的研究准备和评估

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs ...

Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the as-received form, carbon nanomaterials, such as carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs), may contain large agglomerates. Both agglomerates and impurities will diminish the benefits of the unique electrical and mechanical properties offered when CNTs or GNPs are incorporated into polymers or composite material systems. Whilst a variety of methods exist to functionalize carbon nanomaterials and to create stable dispersions, many the processes use harsh chemicals, organic solvents, or surfactants, which are environmentally unfriendly and may increase the processing burden when isolating the nanomaterials for subsequent use. The current research details the use of an alternative, environmentally friendly technique for functionalizing CNTs and GNPs. It produces stable, aqueous dispersions free of harmful chemicals. Both CNTs and GNPs can be added to water at concentrations up to 5 g/L and can be recirculated through a high-powered ultrasonic cell. The simultaneous injection of ozone into the cell progressively oxidizes the carbon nanomaterials, and the combined ultrasonication breaks down agglomerates and immediately exposes fresh material for functionalization. The prepared dispersions are ideally suited for the deposition of thin films onto solid substrates using electrophoretic deposition (EPD). CNTs and GNPs from the aqueous dispersions can be readily used to coat carbon- and glass-reinforcing fibers using EPD for the preparation of hierarchical composite materials.

Here, a novel method for the functionalization and stable dispersion of carbon nanomaterials in aqueous environments is described. Ozone is injected directly into an aqueous dispersion of carbon nanomaterial that is continuously recirculated through a high-powered ultrasonic cell.

碳纳米材料的功能化和分散使用环境友好的超声波臭氧分解过程

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the ...

环境科学

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Low pressure scanning electron microscopy in a water vapor ambient is used to machine nanoscale to microscale features in carbon nanotube forests.

碳纳米管森林精密铣床使用低压扫描电子显微镜

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

用聚苯乙烯接枝多壁纳米碳纳米管使自组装和各向异性斑块

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

化学

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

C 型60/石墨烯混合纳米结构的制备与表征

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

小型化霍尔推进器的优化、测试和诊断

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...

Synthesis of Graphene Nanofluids with Controllable Flake Size Distributions

A method for synthesizing graphene nanofluids with controllable flake size distributions is presented. Graphene nanoflakes can be obtained by the exfoliation of graphite in the liquid phase, and the exfoliation time is used to control the lower limits of the graphene nanoflake size distributions. Centrifugation is successfully used to control the upper limits of the nanoparticle size distributions. The objective of this work is to combine exfoliation and centrifugation to control the graphene nanoflake size distributions in the resulting suspensions.

A method for synthesizing graphene nanofluids with controllable flake size distributions is presented.

具有可控片状分布的石墨烯纳米流体合成

A method for synthesizing graphene nanofluids with controllable flake size distributions is presented. Graphene nanoflakes can be obtained by the ...

Microscopic Visualization of Porous Nanographenes Synthesized through a Combination of Solution and On-Surface Chemistry

On-surface synthesis has recently been regarded as a promising approach for the generation of new molecular structures. It has been particularly successful in the synthesis of graphene nanoribbons, nanographenes and intrinsically reactive and instable, yet attractive species. It is based on the combination of solution chemistry aimed at preparation of appropriate molecular precursors for further ultra-high vacuum surface assisted transformations. This approach also owes its success to an incredible development of characterization techniques, such as scanning tunneling/atomic force microscopy and related methods, which allow detailed, local characterization at atomic scale. While the surface-assisted synthesis can provide molecular nanostructures with outstanding precision, down to single atoms, it suffers from basing on metallic surfaces and often limited yield. Therefore, the extension of the approach away from metals and the struggle to increase productivity seem to be significant challenges toward wider applications. Herein, we demonstrate the on-surface synthesis approach for generation of non-planar nanographenes, which are synthesized through a combination of solution chemistry and sequential surface-assisted processes, together with the detailed characterization by scanning probe microscopy methods.

<meta charset="utf8"></head><body>通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

A combination of solution and surface assisted synthesis opens new directions in the atomically precise synthesis of nanostructures. Scanning tunneling microscopy (STM) supplemented by non-contact atomic force microscopy (nc-AFM) enables detailed characterization of newly designed and generated carbon-based nano-objects.

同时合成单壁碳纳米管和石墨在电弧等离子体磁增强

摘要

探索更多视频

此视频中的章节