CVD法工业化生产纳米碳管的研究

以乙炔为原料气,用工业化生产炉代替小型实验研究炉批量制备出了纳米碳管,产量为150g/h。TEM图和Raman光谱结果表明,纳米碳管管径均匀分布在20～30 nm间,具有很高的石墨化程度。同时,讨论了生产炉结构、工艺参数以及裂解温度、裂解时间和原料气流量对纳米碳管的影响。     

CVD法工业化生产纳米碳管的研究

以乙炔为原料气,用工业化生产炉代替小型实验研究炉批量制备出了纳米碳管,产量为150g/h.TEM图和Raman光谱结果表明,纳米碳管管径均匀分布在20～30 nm间,具有很高的石墨化程度.同时,讨论了生产炉结构、工艺参数以及裂解温度、裂解时间和原料气流量对纳米碳管的影响.     

CVD一步法制备纳米碳管的研究

CVD法是制备纳米碳管的重要方法。本文研究了以乙炔为原料气，无需预先还原催化剂，以一定的程序速率从500℃升至750℃一步法生长纳米碳管，直接制备出了管径在8-12nm之间，石墨化程度好的纳米碳管。同时，对升温速率、原料气配比等因素进行了讨论，确定了CVD一步法制备纳米碳管较佳条件范围。     

高质量小直径单壁纳米碳管的CVD法制备

使用溶胶凝胶法制备了Fe/Mo/MgO催化剂,用化学气相沉积法在1000℃下催化裂解甲烷,制备了高质量的单壁纳米碳管.用SEM、TEM、HRTEM、TGA和Raman等方法对制备的纳米碳管粗产品进行了表征.结果表明:该产物确为单壁纳米碳管,单壁纳米碳管直径十分均一,在0.86～0.90nm之间,且其形态基本上都是以束状存在;本方法所制得粗产物中单壁碳管的含量在30%以上.     

CVD法制备纳米石墨棒

以甲烷为碳源，在865℃-930℃温度条件下，通过化学气相沉积法，在铁基催化剂上生长出纳米石墨棒。对产物进行X射线衍射分析，确认其为石墨结构，晶粒径估算为16．3nm，长度为200nm～800nm。用透射电子显微镜和激光拉曼光谱仪作进一步的分析，结果表明：产物为纯度较高的纳米石墨棒。     

电弧放电法制备纳米碳管

纳米碳管的制备方法主要有三种：电弧放电法、激光烧蚀法和有机物催化热解法,首先综述了近年来应用电弧放电方法制备纳米碳管的研究进展,然后概述了中国科学院金属研究所在普通电弧法的基础上发展起来的大量制备单壁纳米碳管的氢等离子电弧方法。     

失效AB5型贮氢合金电极材料在制备纳米碳管中的应用

纳米碳管是一种性能优异的新型功能材料.利用循环失效后的AB5型贮氢合金电极材料作为反应催化剂、乙炔气体作为原料气体通过CVD法制备出多壁纳米碳管,研究了经过破碎、清洗、氧化处理后的失效AB5型贮氢合金电极材料在合成纳米碳管中的催化性能,讨论了不同氧化温度处理催化剂对纳米碳管产率、形貌和结构稳定性的影响.结果表明,氧化处理温度对催化剂的催化效能有明显的影响,600℃为最佳氧化处理温度.以氧化处理后的失效AB5型贮氢合金电极材料作为催化剂制备碳纳米管,方法简单易行,为废旧镍氢电池负极材料的回收再利用提供了一种新的思路.     

纳米碳管制备的新进展

本文讨论了有关纳米碳管制备的方法及工艺要求，同时介绍了在纳米碳管制备上的新进展和发展趋势。     

氢等离子电弧法半连续制备单壁纳米碳管

用氢气到代拟气作为缓冲气体,适当改进电弧反应装置并掺加一种生长促进剂可以有效地提高单壁纳米碳管的产量和质量。氢电弧法制备出的单壁纳米碳管堆积成膜状或网状,电镜下可见产物主要由相互缠绕的单壁纳米碳管束构成,纯度较高;激光拉曼分析结果表明制得的单壁纳米碳管直径较大。单壁纳米碳管产物在形貌和结构上的上述特征与氢气和生长促进剂的作用密切相关。     

纳米碳管制备的研究

采用直流电弧法和催化热分解法制备出了纳米碳管，并对这两种方法的工艺进行了初步的探讨，获得了工艺流程和工艺参数。通过实验表明催化热分解法比直流电弧法长出的纳米碳管质量好，产率高，较适于工业化生产。     

气体种类对CVD法制备碳纳米管的影响研究

以甲烷(CH4)和丙烷(C3H6)为碳源气,以纳米级NiO/SiO2气凝胶为催化剂,采用化学气相沉积法(CVD),在合适的工艺条件下,制备出碳纳米管.通过XRD、TEM、BET吸附等手段对制得的碳纳米管进行了表征,考察气体种类对碳纳米管的影响.结果表明:采用两种碳源气制备的碳纳米管,其形貌和结构均有所不同.由CH4制备的碳纳米管长径比大,管壁光滑,形貌规整;而由C3H6制备的碳纳米管,产物中有少量无定形物,且管壁不光滑,有折点出现.     

High-quality single-walled carbon nanotubes synthesis by hot filament CVD on Ru nanoparticle catalyst

We investigated the single-walled carbon nanotubes (SWCNTs) growth on Ru nanoparticle catalyst via hot filament assisted chemical vapor deposition (HFCVD) with two independent W filaments for the carbon precursor (methane) and the hydrogen dissociation respectively. The Ru nanoparticles were obtained following a two-step strategy. At first the growth substrate is functionalized by silanisation, then a self assembly of a ruthenium porphyrin complex monolayer on pyridine-functionalized metal oxide substrates. We have studied the impact of the filaments power and we optimized the SWCNTs growth temperature. The as grown SWCNTs were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. It was found that the quality, density and the diameter of SWCNTs depends on the filament and growth temperature. Results of this study can be used to improve the understanding of the growth of SWCNTs by HFCVD.     

定向碳纳米管的化学气相沉积制备法

报道了一种简便有效的合成定向碳纳米管 (CNTs)的化学气相沉积 (CVD)制备方法。以铁为催化剂 ,乙炔为碳源 ,采用单一反应炉 ,直接在石英基底上沉积催化剂颗粒薄膜 ,成功合成了定向性好、管径均匀的高质量大密度的碳纳米管     

Synthesis of carbon nanotubes at low temperature by filament assisted atmospheric CVD and their field emission characteristics

Multiwalled carbon nanotubes (MWNTs) were synthesized using a hot filament assisted chemical vapor deposition (CVD) at the atmospheric pressure at a substrate temperature of 550 °C. The size of nanotubes was controlled by changing the size of catalyst particles. The structure and composition of these nanotubes were investigated using scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The electron field emission current of MWNTs was also measured. It was found that the nanotubes with smaller the diameter had higher the emission current levels though synthesis conditions except catalyst particles were the same. These as-grown MWNTs had emission current densities of 6.5 mA/cm² and 2.5 mA/cm² at 1 V/μm for 5-8 nm and 20 nm size carbon nanotube samples, respectively. The results indicated that the MWNTs synthesized had low emission threshold voltages and high emission current levels that are favorable properties for field emission-based display device applications.     

Role of catalysts in the surface synthesis of single-walled carbon nanotubes

We demonstrate the role of catalysts in the surface growth of single-walled carbon nanotubes (SWNTs) by reviewing recent progress in the surface synthesis of SWNTs. Three effects of catalysts on surface synthesis are studied: type of catalyst, the relationship between the size of catalyst particles and carbon feeding rates, and interactions between catalysts and substrates. Understanding of the role of catalysts will contribute to our ability to control the synthesis of SWNTs on various substrates and facilitate the fabrication of nanotube-based devices.      

Contactless probing of the intrinsic carrier transport single-walled carbon nanotubes

Intrinsic carrier transport properties of single-walled carbon nanotubes have been probed by two parallel methods on the same individual tubes： The contactless dielectric force microscopy （DFM） technique and the conventional field-effect transistor （FET） method. The dielectric responses of SWNTs are strongly correlated with electronic transport of the corresponding FETs. The DC bias voltage in DFM plays a role analogous to the gate voltage in FET. A microscopic model based on the general continuity equation and numerical simulation is built to reveal the link between intrinsic properties such as carrier concentration and mobility and the macroscopic observable, i.e. dielectric responses, in DFM experiments. Local transport barriers in nanotubes, which influence the device transport behaviors, are also detected with nanometer scale resolution.     

CVD法制备碳纳米管中应用硫添加物的热力学研究

利用俄罗斯科学院研制的CVD (Chemicalvapordeposition)软件计算分析了CH4 H2 S体系在 10 132 5Pa、90 0～ 130 0K ,CO H2 S体系在 10 132 5Pa、90 0～ 12 0 0K下不同硫添加物含量及温度对碳沉积率的影响 ;绘制了碳沉积边界曲线 ,预测了碳沉积区 ;计算筛选出了适合于不同体系制备碳纳米管的催化剂。证明了加入硫添加物可以提高碳纳米管沉积率     

碳纳米管及其掺杂氧化物半导体气敏传感器

碳纳米管气敏传感器以其工作温度低和最低检出限较低等优点而备受关注,而碳纳米管掺杂氧化物半导体气敏传感器兼备了氧化物半导体气敏传感器和碳纳米管气敏传感器二者的优点,具有灵敏度较高、最低检出限低和工作温度低等特性。综述了这两类传感器的研究进展,介绍了其气敏机理,并对相应存在的问题及今后的发展趋势进行了概述。