Large-scale synthesis of BN nanotubes using carbon nanotubes as template

Boron nitride nanotubes (BN-NTs) were synthesized in large scale by the reaction of NaBH₄ and NH₄Cl in the temperature range of 500-600 °C for 10-18 h, where carbon nanotubes (CNTs) were mixed together with the reactants to serve as template. Pure BN-NTs were obtained by oxidizing the product at about 800 °C in air atmosphere. The structure and morphology of the product with a surface area of 106.635 m²/g were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. Large scale preparation of BN-NTs could be realized by this simple and effective route.     

B---C---N nanotubes prepared by a plasma evaporation method

B---C---N nanotubes prepared by a flush evaporation method using a d.c. arc plasma were mainly characterized by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The nanotubes obtained were divided into three types, such as carbon-, boron nitride-, or carbon nanotubes surrounded with boron nitride nanotubes. These types of nanotubes were obtained at temperatures higher than approximately 3000 K; however, these were not formed at temperatures lower than approximately 3000 K. On the other hand, nanocapsules were formed at all the temperature regions, but the nanocapsules obtained were smaller at lower temperatures. The addition of nickel produced a bundle of single walled carbon nanotubes and boron nitride nanocapsules surrounding nickel particles. Based on the experimental data obtained, the formation mechanisms of both nanotubes and nanocapsules were discussed.     

Catalytic synthesis of tubular carbon nanofibers using propagating combustion wave in acetylene

A new method for the pyrolytic synthesis of carbon nanostructures is proposed and experimentally implemented. The synthesis takes place during the propagation of an acetylene combustion wave catalyzed by ferrocene vapor in the absence of oxygen. Under these conditions, long (>10 μm) tubular carbon nanofibers with an external diameter of 10–60 nm and a wall thickness of up to 5 nm were obtained. The proposed method is characterized by a high rate of synthesis and low energy consumption, which implies good prospects for the development of an effective catalytic technology for the synthesis of carbon nanotubes.     

Surface modification of carbon nanofibers with platinum nanoparticles using a “polygonal barrel-sputtering” system

Carbon nanofibers (CNFs) modified with Pt nanoparticles have been prepared using a new RF sputtering instrument called a “polygonal barrel-sputtering” system. The prepared samples were characterized by optical microscopy, field emission scanning microscopy (FE-SEM), inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluorescence (XRF), X-ray diffraction (XRD), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectrometry (EDS). When only the CNFs were placed in the system, large CNF aggregates with sizes of 5-15 mm were observed and Pt was deposited non-uniformly. In addition, microscopic observations revealed that ca. 40% of the CNFs were still unmodified. In contrast, when pieces of bent columnar stainless steel were placed in the system with the CNFs, large CNF aggregates were not observed in the Pt deposited sample. In this sample, CNFs modified with highly dispersed Pt nanoparticles were obtained successfully, and unmodified CNFs were absent. The sizes of the Pt nanoparticles were in a narrow range of 1.7-3.5 nm, and their mean size was 2.5 nm.     

The growth of carbon nanotubes on large areas of silicon substrate using commercial iron oxide nanoparticles as a catalyst

A new approach to chemical vapour deposition (CVD) growth of carbon nanotubes (CNTs) using commercial magnetite nanoparticles, avoiding its in situ synthesis, is reported. Commercial magnetite nanoparticles were used as catalyst material to growth multiwalled carbon nanotubes by chemical vapour deposition onto a silicon substrate of several square centimeters in area. It is shown that the application of an alternating electric field during the deposition of catalytical nanoparticles is an effective technique to avoid their agglomeration allowing nanotube growth. Scanning electron microscopy showed that the nanotubes grow perpendicularly to the substrate and formed an aligned nanotubes array. The array density can be controlled by modifying the deposited nanoparticle concentration.     

Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method

Submicron carbon spherical particles were obtained by polycondensation of resorcinol and formaldehyde in a solution and subsequent ultrasonic spray pyrolysis of the prepared sol. Microscopic characterization indicates the regular spherical shape of the obtained particles and sphere diameters in 200-700 nm range. The carbon spheres are amorphous as confirmed by electron diffraction, EELS, XRD and HREM characterization. Activation procedure was performed with H₂O in a nitrogen flow for 15 and 30 min at 800 °C. The activation procedure preserved the initial spherical shapes of the particles while the particle porosity and specific surface area were increased. The amount of surface oxygen functionalities was also increased by activation procedure as indicated by FTIR analysis.     

流动催化热解法制备高质量多壁碳纳米管的研究

以甲烷为碳源,N2和H2作载气,二茂铁作催化剂前驱体,采用流动催化热解法制备出大量高质量取向性好的多壁碳纳米管(MWCNTs)。利用扫描电子显微镜(SEM),透射电子显微镜(TEM)和Raman光谱对碳纳米管的形貌和结构进行了表征。该制备过程工艺简单并且成本低廉,对实现碳纳米管的规模生产具有重要意义。     

Preparation and electrical properties of Ga-doped ZnO nanoparticles by a polymer pyrolysis method

In this article, preparation of Ga-doped zinc oxide (GZO) nanoparticles by a polymer pyrolysis method is reported. The pyrolysis behaviors of the polymer precursors prepared via the in situ polymerization of metal salts and acrylic acid are analyzed using thermalgravity-differential scanning calorimetry (TG-DSC) techniques. Then, the structural characteristics of the products are studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It is revealed by the results that the GZO nanoparticles calcined at 600 °C show good crystallinity with the wurtzite structure. GZO nanoparticles doped with 4 mol% Ga have a mean particle size of 26 nm with spherical-like morphology. Electrical resistivity measurement shows that, before and after high temperature annealing under H₂ atmosphere, the resistivity of the GZO nanoparticles is decreased by one and four orders in magnitude, respectively, compared with the pure ZnO nanoparticles. In addition, due to its versatility, this in situ polymer pyrolysis method can be easily extended to synthesis of other n-type doped semiconductor, such as In and Al doped ZnO or Sb doped SnO₂.     

用气相流动催化热解法合成单壁碳纳米管

以正硅酸乙酯(TEOS)为前驱体，二茂铁为催化剂前驱体，利用气相流动催化热解法在850～1160℃连续合成了单壁碳纳米管(SWNTs)．在此过程中，以由TEOS分解得到的二氧化硅颗粒和二茂铁分解得到的铁颗粒在气流中直接形成的复合粒于作为催化剂，二氧化硅作为铁颗粒的载体．电于显微镜和激光拉曼光谱的观测和分析表明，在所得到的产物中SWNTs的含量约为10％，其直径为1～2nm。     

Microstructural evolution of iron oxide hollow nanoparticles toward iron oxide nanotubes in a prolonged sintering condition

Prolonged sintering of iron oxide hollow nanoparticles (HNPs) during chemical vapor condensation (CVC) at 800 °C for 6 h showed some interesting morphologies of the iron oxide nanotubes. TEM and XRD studies confirmed that single-walled nanotubes of a mixed phase of α, β, and γ-Fe₂O₃, with a wall thickness of less than 10 nm and an outer diameter of approximately 50 nm were synthesized. The formation of iron oxide nanotubes was thought to be an evolution of iron oxide HNPs based on the sintering.     

快速热解法制备炭包覆纳米金属磁性颗粒(英文)

以简单金属前躯体为原料通过快速热解法制备炭包覆纳米金属磁性颗粒,通过透射电镜、X-射线衍射、热重-示差扫描同步热分析及振动样品磁强计等对产物形貌、结构、成分与磁性能进行表征。结果表明:采用该方法制备的炭包覆纳米金属磁性颗粒形状为近球形颗粒,粒径均一,其中炭包覆镍纳米磁性颗粒的粒径集中在10nm～30nm范围,炭包覆铁纳米磁性颗粒粒径则在50nm～60nm范围;所制炭包覆纳米金属磁性颗粒在室温下具有顺磁性,其磁性能随金属颗粒含量的变化而改变。该方法有望发展成一种工艺简单,可进行连续工业化生产炭包覆纳米金属磁性颗粒的方法。     

酞菁铁固态热裂解制备新型炭纳米材料

研究了酞菁铁在密封体系中固态热裂解制备新型炭纳米材料的方法。通过这种方法，可以大量制备排列整齐又很直的碳纳米管。实验发现，升高热裂解温度，尤其温度高于800℃时，有利于碳管的生长。同时，这种方法还是一种非常有效的制备特殊结构纳米炭材料的方法。如用这种方法可以得到很长的具有电缆型结构的纳米炭，在其中具有单晶结构的炭化铁形成了电缆的金属芯。其他一些特殊炭结构，如项链型炭结构、管中管炭结构等也可以用这种方法制备出来。     

The preparation of carbon nanotubes by dc arc discharge using a carbon cathode coated with catalyst

Carbon nanotubes (CNTs) were grown using a dc arc discharge process and relevant process parameters were investigated. Unlike the usual process in which a carbon anode is filled with metal catalyst powder, CNTs were prepared using a carbon cathode on which the metal catalyst had been deposited using an electroplating system. Various transition metals were investigated. The results show that multi walled carbon nanotubes (MWNTs) and single walled carbon nanotubes (SWNTs) can both be synthesized using this technique. SWNTs are detected in the soot sample collected around the cathode, whereas the MWNTs are detected mainly in the deposit sample collected from the central area of the cathode. The CNT yield varies depending on the catalyst used and the properties of a good catalyst are discussed.     

Effects of PVP and KCl concentrations on the synthesis of gold nanoparticles using a solution plasma processing

Application of plasma in an aqueous environment, so called Solution Plasma Processing (SPP) is a recent development. Solution plasma processing for the synthesis of gold nanoparticles by reducing HAuCl₄ in the presence of Polyvinylpyrrolidone (PVP) and potassium chloride (KCl) was investigated in this work. Effects of PVP and KCl concentrations on the size and the shape of the gold nanoparticles in SPP were studied using a UV-vis nir spectrophotometer, and high resolution transmission electron microscopy (HRTEM). The results showed that the shape and size of the nanoparticles were affected by various KCl and PVP concentrations. The average particle size of the gold nanoparticles synthesized by SPP decreased with an increase in PVP concentration and the particle shape became more spherical with the addition of KCl. The HRTEM results indicated that gold nanoparticles with a diameter less than 10 nm were single crystals, while particles with a diameter greater than 15 nm were polycrystalline.     

喷雾热解法制备高产率石墨/炭纳米纤维及其特征研究

基于石墨/炭纳米纤维(GNFs)的克量级(>1 g)制备及其特征表征,通过苯的喷雾热解制备了GNFs,并采用XRD,TEM及SEM对GNFs进行了表征.结果表明:高产率GNFs的最佳生长条件是:喷管内径～0.52mm,苯液流量～5 mL/min,反应温度～750℃,载气H2流量～1 500 mL/min.所制GNFs的典型长度和直径分别为～60um和～250 nm,大部分GNFs样品呈现螺圈/螺旋纤维状.喷雾热解生长模式中GNFs的产率为克量级(1.45 g)/产程.     

Large scale synthesis and characterization of Ni nanoparticles by solution reduction method

Ni nanoparticles were mass synthesized by solution reduction process successfully. The influence of the parameters on the particle size of Ni nanoparticles were studied and the referential process parameters were obtained. The morphology and structure of the synthesized Ni nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and infrared spectroscopy (IR). The results show that Ni nanoparticles are of high purity and are covered by hydroxyethyl carboxymethyl cellulose (HECMC) layer and the mean size being about 31 nm. The magnetic measurement revealed that Ni nanoparticles are ferromagnetic.     

A chemical method to graft carbon nanotubes onto a carbon fiber

A simple method is developed for grafting carbon nanotubes (CNTs) onto a carbon fiber surface. CNT and carbon fiber undergo an oxidation treatment. Oxidation generates oxygen, like carboxyl, carbonyl or hydroxyl groups, or amine groups on nanotubes and carbon fiber surface. Functionalized CNTs are dispersed in a solvent and deposited on carbon fibers. The bonds between CNT and carbon fiber are operated by esterification, anhydridation or amidization of the chemical surface groups. The resulting materials are characterized by scanning electron microscopy (SEM). CNTs form a 3D network around the carbon fibers. Likewise, CNT bonding between two fibers is observed.     

Preparation of carbon nanotubes with iron nanowires inside using a simple microwave-based method

The importance of synthesizing carbon nanotubes with iron nanowires inside (Fe-MWNTs) via microwave radiation lies in the fact that it allows to improve aspects such as selective and uniform heating of the sample, reduction of the time of synthesis, avoiding complex experimental procedures and lowering the cost of production. In this paper we synthesize and characterize carbon nanotubes with iron nanowires inside using a mixture of graphite and iron acetate powders as starting materials and a 900 W domestic microwave oven used as power source. A mixture of the starting materials inside a vacuum sealed quartz ampoule was subjected to radiation for 7 min. As a result straight Fe nanowires are obtained with lengths between 5 and 15 microns, and a wide variety of partially Fe filled nanotubes with diameters in the 30–80 nm range. Samples were characterized with scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.     

乙炔等离子体热解法制备C60的研究

用乙炔高频等离子体热解法连续大批量合成含富勒烯的碳灰。用透射电镜（TEM）、X射线衍射（XRD）、紫外－可见光谱（UV－Vis）、红外光谱（IR）等测试手段对碳灰进行了分析研究，并测定了富勒烯C60的产率为2．5g／h。