Fe催化PAN炭纤维原位生长纳米炭纤维

为了研究气相生长纳米炭纤维在炭／炭复合材料制备中的应用，采用均热式化学气相沉积技术，以针刺PAN炭纤维薄毡为基体，二茂铁为催化剂前驱体，丙烯为炭源，氮气为载气，在炉压1．0kPa-1.3kPa，沉积温度880℃、920℃下进行了Fe催化PAN炭纤维原位生长纳米炭纤维的实验。经不同时间沉积后的样品在扫描电镜（SEM）下进行观察，发现880℃时沉积4h后在PAN炭纤维周围生成大量的原位生长纳米炭纤维，而在920℃时因催化剂失效导致热解炭对Fe催化剂颗粒包覆，形成颗粒状热解炭。     

碳化硅纳米纤维/炭纤维共增强毡体的制备

以电镀Ni颗粒为催化剂,采用化学气相沉积(CVD)法,在炭纤维表面原位生长SiC纳米纤维(SiC-NF),制备出SiC纳米纤维/炭纤维共增强毡体.XRD和SEM分析表明生成的SiC纳米纤维物相为β-SiC,平均长度可达几十微米,直径在几十到几百个纳米之间.通过改变电镀镍的时间,研究了催化剂Ni颗粒的大小、形态及分布对SiC-NF生长情况的影响,研究结果表明,催化剂Ni颗粒分布越细小、均匀,催化活性越大,所生长的纳米SiC纤维也越细长,分布越均匀.     

用催化剂控制硅纳米线直径的研究

本文研究了固－液－固（SLS）生长机制中催化剂与硅纳米线直径的关系。发现Si片上沉积的催化剂厚度和种类对硅纳米线的直径都有一定的影响，当使用Ni做催化剂时，硅纳米的直径与Ni膜厚度有关。其中硅纳米线的最大直径随催化剂厚度减小而减小，但最小直径基本不改变，当用Au做催化剂时，硅纳米线的平均直径和直径分布最小（10nm-20nm）。但硅纳米的直径不随Au膜厚度减小而减小。     

纳米碳管/氧化锌异质结构的合成及发光性质

以纳米碳管（CNTs）为基体、铜为催化剂,采用催化碳热还原方法直接合成出具有异质结构的纳米碳管/氧化锌（CNT/ZnO）复合材料。利用扫描电镜、透射电镜及X射线衍射等手段研究了异质结构CNT/ZnO复合材料的形态和结构。发现氧化锌纳米线在纳米碳管表面的生长过程遵循催化剂诱导的汽-液-固（VLS）机制;氧化锌纳米线与铜催化剂和纳米碳管之间分别存在明显的界面,并且氧化锌纳米线与纳米碳管均保持了规整的晶体结构。同时也发现在大直径纳米碳管上易于形成高密的氧化锌纳米线;随沉积温度的升高ZnO的形态由线到棒最后形成颗粒。异质结构CNT/ZnO复合材料的诱导发光性能不同于氧化锌纳米线和纳米碳管,在蓝光区域的发光强度远大于紫外发光强度。     

乙烯催化裂解法选择性合成纳米炭纤维

通过采用不同金属催化剂进行乙烯催化裂解制备了具有不同微观结构的纳米炭纤维。利用纳米二氧化硅负载的铁、镍以及铁镍合金催化剂在适当的反应条件下分别制备了管状、实心鱼骨状以及空心鱼骨状的纳米炭纤维。由于金属催化剂与纳米二氧化硅间的强相互作用导致在低反应温度下也能达到高的反应活性，所以能够合成出高收率、小直径而且分布均匀的纳米炭纤维。不同结构的纳米炭纤维归因于金属催化剂的不同分散性以及不同的生长机理。通常利用铁催化剂进行乙烯裂解制备纳米炭纤维需要高于650℃，但是在我们的实验中发现500℃低温下利用纳米二氧化硅负载的铁催化剂进行乙烯裂解就能够合成出管状纳米炭纤维。     

气相催化裂解法制备微米级螺旋形炭纤维的研究

以商用乙炔为碳源，镍板为催化剂，含硫化合物为助催化剂，通过气相催化裂解法（VCC）制得了微米级螺旋形炭纤维。通过对影响微螺旋形炭纤维生长因素研究。发现将镍板直立放置于石英管中，可以提高螺旋形炭纤维的收率。同时发现反应温度为710℃～800℃，C2H2/H2=1：3。含硫化合物的流量为1.0mL/min～1.2mL/min时，有利于规整螺旋纤维的生成，通过调节N2的流量，可以获得螺径不同的炭纤维。气体总流量约200mL/min时可制得螺径约4μm的规整炭纤维；气体总流量约150mL/min时可获得螺径约20μm的炭纤维。利用扫描电子显微镜（SEM）考察了螺旋纤维的微观形貌，发现所得的纤维几乎为双螺旋，同时在螺旋纤维生长的先端常观察到由弯曲纳米级纤维形成的绒状物。     

炭纤维网布/螺旋碳纤维复合材料制备及电磁性能研究

以炭纤维网布为基体,通过电镀工艺在炭纤维网布上形成Ni催化剂膜,采用化学气相沉积方法原位合成炭纤维网布/螺旋纳米碳纤维复合材料,采用扫描电镜(SEM)、Raman光谱和X射线衍射仪(XRD)对生长的螺旋纳米碳纤维的形态和结构进行表征。考察主要反应因素—温度对螺旋纳米碳纤维生长的影响,并就生长过程进行了讨论;对其制备出的炭纤维网布/螺旋纳米碳纤维复合材料在8.2～12.4GHz频段的电磁性能进行分析,考察其吸波性能。结果表明制备出的炭纤维网布/螺旋纳米碳纤维复合材料比单一的螺旋纳米碳纤维具有更高的电磁损耗角正切,电损耗正切值由0.7提高到3.8,表明复合材料具有较好的吸波性能。     

一维纳米结构的金属催化合成与生长机理

金属催化合成法是合成一维无机纳米材料最重要、最成功的方法。本文以生长机理（包括气-液-固、气-固-固、溶液-液-固、超临界流体-液-固、超临界流体-固一固、固-液-固和广义气-液-固等）为线索,系统阐述了金属催化法在一维无机纳米结构的制备和生长机理研究方面的最新进展。最后,我们指出了金属催化法在制备技术和生长机理研究方面存在的一些问题并提出了一些可能的解决途径。     

不同催化剂作用下生长的碳纳米管和碳纳米纤维复合膜的电吸附性能(英文)

采用低压低温气相沉淀法在不同催化剂(Fe和Ni)作用下制备碳纳米管-碳纤维复合薄膜,并研究其电容去离子行为,结果表明:在Ni催化作用下石墨上生长的碳纳米复合薄膜电极的去离子能力比Fe催化作用下生长的碳纳米复合薄膜电极的强;并且碳纳米复合薄膜的电吸附遵循langmuir单层等温吸附.     

介孔材料对纳米碳管制备及结构的影响

本文报道了制备含Fe的硅介孔材料以及利用该介孔材料生长纳米碳管的工艺条件.利用化学气相沉积法,以含有Fe的介孔材料为催化剂,在800%条件下催化分解乙炔气体制备纳米碳管,同时利用扫描电子显微镜（SEM）及透射电子显微镜（TEM）对制备的纳米碳管的形貌及结构进行观察表征.实验结果表明该介孔材料可以在一定程度上控制纳米碳管的结构及形貌,得到直径均一、笔直开口的纳米碳管.     

纳米炭纤维的储氢性能初探

主要阐述了用流动催化剂法制备的纳米炭纤维的储氢特性,发现在室温下纳米炭纤维可以快速大量吸氢纳米炭纤维的储氢量远远高于目前各种储氢材料的储氢容量100nm左右的炭纤维的储氢容量高达10％以上（质量分数）,如此高的储氢容量使其在燃料电池等方面具有厂阔的应用前景.     

气相生长纳米碳纤维表面化学镀镍

气相生长纳米碳纤维（ＶＧＣＮＦ）经活化、敏化和催化预处理后、用化学镀（自催化沉积）的方法,在碱性镀液中实施化学镀镍。利用ＳＥＭ观察了镀层的形貌。并利用能主普分析测试了镀层的组成。在气相生长纳米碳纤维聚集体的内层纤维表面沉积了许多细小Ｎｉ颗粒,而外层纤维表面上沉积的是连续、均匀的镍镀层,它们是由许多Ｎｉ颗粒相互堆积连结而形成,除含磷外几乎不含其它杂质,同时,还初步探讨了镍在气相生长纳米碳纤维表面自催化沉积过程。     

Hydrothermal synthesis of β-nickel hydroxide nanocrystalline thin film and growth of oriented carbon nanofibers

Novel well-crystallized β-nickel hydroxide nanocrystalline thin films were successfully synthesized at low temperature on the quartz substrates by hydrothermal method, and the oriented carbon nanofibers (CNFs) were prepared by acetylene cracking at 750 °C on thin film as the catalyst precursor. High resolution transmission electron microscopy (HR-TEM) measurement shows that thin films were constructed mainly with hexagonal β-nickel hydroxide nanosheets. The average diameter of the nanosheets was about 80 nm and thickness about 15 nm. Hydrothermal temperature played an important role in the film growth process, influencing the morphologies and catalytic activity of the Ni catalysts. Ni thin films with high catalytic activity were obtained by reduction of these Ni(OH)₂ nanocrystalline thin films synthesized at 170 °C for 2 h in hydrothermal condition. The highest carbon yield was 1182%, and was significantly higher than the value of the catalyst precursor which was previously reported as the carbon yield (398%) for Ni catalysts. The morphology and growth mechanism of oriented CNFs were also studied finally.     

Nano-epoxy resins containing electrospun carbon nanofibers and the resulting hybrid multi-scale composites

For the first time, electrospun carbon nanofibers (ECNFs, with diameters and lengths of ∼200 nm and ∼15 μm, respectively) were explored for the preparation of nano-epoxy resins; and the prepared resins were further investigated for the fabrication of hybrid multi-scale composites with woven fabrics of conventional carbon fibers via the technique of vacuum assisted resin transfer molding (VARTM). For comparison, vapor growth carbon nanofibers (VGCNFs) and graphite carbon nanofibers (GCNFs) were also studied for making nano-epoxy resins and hybrid multi-scale composites. Unlike VGCNFs and GCNFs that are prepared by bottom-up methods, ECNFs are produced through a top-down approach; hence, ECNFs are more cost-effective than VGCNFs and GCNFs. The results indicated that the incorporation of a small mass fraction (e.g., 0.1% and 0.3%) of ECNFs into epoxy resin would result in substantial improvements on impact absorption energy, inter-laminar shear strength, and flexural properties for both nano-epoxy resins and hybrid multi-scale composites. In general, the reinforcement effect of ECNFs was similar to that of VGCNFs, while it was higher than that of GCNFs.     

平直碳纳米纤维与螺旋碳纳米纤维的共同生长

研究了采用乙醇催化燃烧法制备的碳纳米纤维的形貌和结构，并且讨论了平直碳纳米纤维与螺旋碳纳米纤维分别对应的生长机制。分析结果表明在特定的实验条件下，可以制备出平直碳纳米纤维与螺旋碳纳米纤维的共生材料。螺旋碳纳米纤维的生长机制是基于催化剂颗粒的各向异性。本实验方法具有制备工艺简单，碳源无毒性，制备过程无环境污染等特点，因而有望实现大量生产。     

Large-scale synthesis of segmented carbon nanofibers by catalytic decomposition of acetylene on fan shaped foam Ni

Large-scale synthesis of segmented carbon nanofibers (SCNFs) by catalytic decomposition of acetylene on fan shaped foam Ni in an improved conventional reactor is reported. The procedure can be scaled up for semi-continuous production of the deposits. The effects of the reaction conditions on the growth of the segmented carbon nanofibers are discussed. Samples of the deposits in as-prepared state were examined by means of XRD, SEM, TEM and HRTEM. The results indicate that a semi-continuous synthesis of 10 g of deposits with about 90% segmented nanofibers was obtained at flow rate of acetylene 15 ml/min and hydrogen 150 ml/min at temperature 600∘C for 30 min. The HRTEM image revealed that the fibers are stacked with well ordered graphitic platelets intermittently spaced by less ordered graphitic platelets perpendicular to the axis of the fiber. The growth mechanism of the segmented carbon nanofibers is also discussed.     

The effect of catalyst evolution at various temperatures on carbon nanostructures formed by chemical vapor deposition

Solid carbon nanofibers (CNFs), hollow CNFs, metal-filled carbon nanotubes (CNTs), and carbon onions were synthesized by chemical vapor deposition (CVD) using a novel Ni/Y catalyst supported on Cu at different reaction temperatures. XRD, TEM, and EDS analyses reveal that the structure of the catalyst changes with increasing reaction temperature. The evolution of Y doped in Ni directly influences the morphologies of the products. At relatively low temperature, Y is doped in Ni and causes CNF formation, and when the temperature is increased to above 650 °C, Y separates from Ni as yttria nanoparticles and carbon onions are synthesized. The catalyst evolution and carbon nanostructure growth mechanism are discussed in detail.     

Functions of amorphous carbon in catalyst fabrication for carbon nanofiber growth in the poly(ethylene glycol) thermal decomposition method

To investigate the growth mechanism of carbon nanofibers (CNF) through a process using the thermal decomposition of poly(ethylene glycol) (PEG), we researched the phenomena that occurred from PEG decomposition to CNF growth during a temperature elevation process of CNF synthesis. In the PEG thermal decomposition method, the selective synthesis of platelet CNF (PCNF) and cup-stacked CNF was accomplished by changing only the ramp rate (without any other difference in experimental conditions). As a result, it was confirmed that carbon-containing gases generated by PEG thermal decomposition were converted to amorphous carbon and deposited on the substrate. There was a clear correlation between the amount of deposited amorphous carbon and the size of the nickel catalyst particle for CNF growth. Therefore, in the PEG thermal decomposition method, amorphous carbon deposition was found to be important to control the dispersity and morphology of the catalyst particle, and it was probably crucial to the determination of the type of CNF. In addition, the PCNF prepared in this study showed multidirectional growth from polyhedral catalyst particles, and this could be why the PEG thermal decomposition was able to create PCNF with small diameters compared to PCNF synthesized by conventional methods.     

Preparation of carbon nano-microcoils by Ni3S2-catalyzed pyrolysis of acetylene and its vapor-liquid-solid-solid growth mechanism

Carbon microcoils are generally prepared by catalytic chemical vapor deposition of acetylene, using Ni as the catalyst and thiophene as the promoter. In this work, Ni3S2 was chosen as the catalyst on purpose to avoid the introducing of noxious and unpleasant thiophene during the reaction process. The products obtained in the temperature range of 1013-1033 K were pure, regular and had perfect morphology. Using transmission electron microscope, Raman spectrometer and X-ray diffractometer, the microstructure of the as-prepared carbon microcoils were characterized, furthmore, energy dispersive spectrum and selected area electron diffraction analysis reveal that the growth of carbon microcoils is always accomplished with the transformation of the catalyst from Ni3S2 to Ni3C. We first observed that the fiber constructing the carbon microcoil is composed of three sub-fibers, which strongly supports the proposition of vapor-liquid-solid-solid growth mechanism. In this mechanism, every catalyst particle is in the state of the coexistence of solid and liquid. Carbon atoms firstly permeate into the liquid portion from gas, then disperse into the solid portion, and finally deposit from the catalyst grain to form the carbon microcoil.