Decorating carbon nanotubes with Cobalt nanoparticles

A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with Cobalt nanoparticles was synthesized successfully by a simple chemical precipitation and deoxidization method. The composite was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The pattern of XRD indicated that MWNTs and Cobalt nanoparticles coexisted in the composite. The TEM images revealed that the Cobalt nanoparticles were distributed on the surface of the MWNTs, with the size ranging from 5 to 15 nm. The hysteresis loops of the decorated MWNTs were measured by a vibrating sample magnetometer (VSM), the ferromagnetic signature emerged with the saturated magnetization of 5.8 emu/g, and the coercive of 310 Oe.     

Assemblies of carbon nanotubes and unencapsulated sub-10-nm gold nanoparticles

The development of assemblies consisting of unencapsulated, sub-10-nm gold particles attached to individual carbon nanotubes (CNTs) with diameters of 2 nm is described. The assemblies are formed on the surface of a porous anodic alumina (PAA) template on which the CNTs (single- or double-walled) are grown by plasma-enhanced chemical vapor deposition. The Au nanoparticles are formed through an indirect evaporation technique using a silicon nitride membrane mask, and diffuse along the PAA surface into the regions containing CNTs. The nanoparticles bind relatively strongly to the CNTs, as indicated by observations of nanoparticles that are suspended over pores or that move along with the CNTs. This approach may provide a new method to functionalize CNTs for chemical or biological sensing and fundamental studies of nanoscale contacts to CNTs.     

纳米镍颗粒填充碳纳米管的制备与磁性能

采用自制的实验装置, 通过阳极弧放电等离子体技术成功制备了Ni纳米颗粒填充的碳纳米管, 利用高分辨透射电子显微镜(HRTEM)、 XRD、 TEM、 X射线能量色散分析谱仪(XEDS)和振动样品磁强计(VSM)等测试手段对样品的化学成分、 形态、 微观结构和磁性能进行了表征。实验结果表明, 采用本文中实验方法能获得大量被纳米金属颗粒填充的碳纳米管, 其内部填充物为面心立方(FCC)结构的纳米Ni颗粒, 外围薄层为石墨碳层。碳纳米管的外径为30~40 nm, 壁厚5~8 nm, 内部填充的纳米颗粒呈球形和椭球形, 粒径均匀, 在管腔内不连续分布。产物具有顺磁特性, 矫顽力是78 Oe, 饱和磁化强度是33 enu/g。     

Metal nanoparticles and related materials supported on carbon nanotubes: methods and applications

Carbon nanotubes are one of the most intensively explored nanostructured materials. In particular, carbon nanotubes are unique and ideal templates onto which to immobilize nanoparticles allowing the construction of designed nanoarchitectures that are extremely attractive as supports for heterogeneous catalysts, for use in fuel cells, and in related technologies that exploit the inherent 'smallness' and hollow characteristics of the nanoparticles. Here we overview the recent developments in this area by exploring the various techniques in which nanotubes can be functionalized with metals and other nanoparticles and explore the diverse applications of the resulting materials.     

3-D characterization of CdSe nanoparticles attached to carbon nanotubes

The crystallographic structure of CdSe nanoparticles attached to carbon nanotubes has been elucidated by means of high resolution transmission electron microscopy and high angle annular dark field scanning transmission electron microscopy tomography. CdSe rod-like nanoparticles, grown in solution together with carbon nanotubes, undergo a morphological transformation and become attached to the carbon surface. Electron tomography reveals that the nanoparticles are hexagonal-based with the (001) planes epitaxially matched to the outer graphene layer. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users.     

Effect of Co and Ni nanoparticles formation on carbon nanotubes growth via PECVD

The effect of cobalt (Co) and nickel (Ni) nanoparticle catalysts on the growth of carbon nanotubes (CNTs) were studied, where the CNTs were vertically grown by plasma enhanced chemical vapour deposition (PECVD) method. The growth conditions were fixed at a temperature of 700 °C with a pressure of 1000 mTorr for 40 minutes with various thicknesses of sputtered metal catalysts. Only multi-walled carbon nanotubes are present from the growth as large average diameter of outer tube (～10–30 nm) were measured for both of the catalysts used. Experimental results show that high density of CNTs was observed especially towards thicker catalysts layers where larger and thicker nanotubes were formed. The nucleation of the catalyst with various thicknesses was also studied as the absorption of the carbon feedstock is dependent on the initial size of the catalyst island. The average diameter of particle size increases from 4 to 10 nm for Co and Ni catalysts. A linear relationship is shown between the nanoparticle size and the diameter of tubes with catalyst thicknesses for both catalysts. The average growth rate of Co catalyst is about 1.5 times higher than Ni catalyst, which indicates that Co catalyst has a better role in growing CNTs with thinner catalyst layer. It is found that Co yields higher growth rate, bigger diameter of nanotube and thicker wall as compared to Ni catalyst. However, variation in Co and Ni catalysts thicknesses did not influence the quality of CNTs grown, as only minor variation in I_G/I_D ratio from Raman spectra analysis. The study reveals that the catalysts thickness strongly affects not only nanotube diameter and growth rate but also morphology of the nanoparticles formed during the process without influencing the quality of CNTs.     

Fabrication of a room temperature hydrogen sensor based on thin film of single-walled carbon nanotubes doped with palladium nanoparticles

A new sensor for the detection of hydrogen at parts per million (ppm) levels was fabricated by coating a thin film of palladium-doped activated single-walled carbon nanotube on the inner wall of a glass tube. The response of the sensor was based on the changes in the impedance of the sensor upon the adsorption of hydrogen molecules. The linear dynamic range of the sensor was from 1 to 50?ppm. The relative standard deviation of six replicate analyses of 5?ppm of H₂ was 2.1% and the limit of detection was 0.73?ppm for H₂ species. Humidity, methane and hydrogen sulphide did not have any serious effect on hydrogen recognition. Also, no interfering effect was observed when 20-fold excess (mass/mass) of carbon dioxide or carbon monoxide was present with hydrogen.     

Dispersion of metal nanoparticles on carbon nanotubes with few surface oxygen functional groups

Homogeneous dispersion of metal oxide nanoparticles was achieved on carbon nanotubes (CNTs) even with a very small amount of surface oxygen functional groups (SOFGs) aided by using ethylene glycol (EG) and sodium hydroxide during the process. Similar particle size distributions were obtained for iron deposited on CNTs containing various amounts of SOFGs. We proposed that formation of hydrogen bonds between EG on the CNT surface and sodium hydroxide is likely responsible, which creates precipitating sites for iron ions on the CNT surface. This facile method is expected to find applications not only for catalysis but also in the fields such as sensors and magnetic materials in particular where a perfect sp² hybridized carbon structure is preferred.     

碳纳米管承载纳米Fe_3O_4颗粒的制备(英文)

采用一种简单又经济的方法将Fe3O4纳米颗粒填充到碳纳米管中。透射电镜(TEM)、扫描电镜(SEM)及其能谱附件(EDX)和X射线多晶衍射(XRD)测试结果表明:Fe3O4纳米颗粒成功地填充到碳纳米管中。材料的磁性能测试结果表明:碳纳米管中填充Fe3O4纳米颗粒后,在常温下具有超顺磁性,其饱和磁化强度由0.35emu/g增大到了13.15emu/g。Fe3O4纳米颗粒填充的碳纳米管可望应用于工程和医学领域。     

多壁碳纳米管负载镁掺杂氧化锌纳米颗粒的研究

利用醋酸锌和醋酸镁为原料,无水乙醇为溶剂,草酸为沉淀剂,通过共沉淀法和后续热处理实现多壁碳纳米管表面负载镁掺杂氧化锌纳米颗粒,并使用X射线衍射仪、扫描电子显微镜、透射电子显微镜和紫外吸收光度计研究复合材料的形貌和光学性能。电子显微镜结果表明,在450℃热处理下,多壁碳纳米管表面能够均匀地负载镁掺杂氧化锌纳米颗粒,其颗粒粒径大约为10～20nm。紫外吸收光谱结果说明,镁掺杂显著地提高多壁碳纳米管/氧化锌复合材料的紫外吸收性能,而且其紫外吸收峰向短波方向蓝移达22nm。     

Si元素对碳纳米管增强铝基复合泡沫组织与性能的影响

针对金属基复合材料,添加合金元素是提升其综合性能的有效途径.本文通过高能球磨和填加造孔剂法,制备了添加Si元素的碳纳米管(CNTs)增强铝基(CNTs/Al-Si)复合泡沫,通过准静态压缩实验测试其压缩性能和吸能性能,进一步研究烧结温度和不同Si元素含量对CNTs/Al-Si复合泡沫微观组织、压缩性能和吸能性能的影响,...     

硼掺杂对碳纳米管形貌和磁性能的影响

以碳纳米管为原料,利用真空封管技术在高温下用硼粉对碳纳米管进行掺杂处理,获得了碳化硼纳米管(纤维).利用透射电子显微镜、X射线衍射、X射线光电子能谱和磁性测试设备对样品的形貌、结构、组分和磁性能进行了表征.结果表明,掺硼后的碳纳米管(纤维)不仅在形貌上有很大改变,而且其磁性能也有了很大的改变.     

Photocatalytic activity of a new composite material of Fe (III) oxide nanoparticles wrapped by a matrix of polymeric carbon nitride and amorphous carbon

Polymeric carbon nitride was synthesized from urea and doped with Cu and Fe to act as co-catalysts. The material doped with Fe was a new composite material composed of Fe(III) oxides (acting as a co-catalyst) wrapped by the polymer layers and amorphous carbon. Furthermore, the copper doped material was described in a previous report. The photocatalytic degradation of the azo dye direct blue 1 (DB) was studied using as photocatalysts: pure carbon nitride (CN), carbon nitride doped with Cu (CN-Cu) and carbon nitride doped with Fe (CN-Fe). The catalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), by X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller method (BET), etc. The adsorption phenomenon was studied using the Langmuir and Freundlich models. For the kinetic study, a solution of 500 mg L^?1 of DB1 was treated with each catalyst, visible light and H₂O₂. The dye concentration was measured by spectrophotometry at the wavelength of 565 nm, and the removal of the total organic content (TOC) was quantified. BET analysis yielded surface areas of 60.029, 20.116 and 70.662 m²g^?1 for CN, CN-Cu and CN-Fe, respectively. The kinetics of degradation were pseudo-first order, whose constants were 0.093, 0.039 and 0.110 min^?1 for CN, CN-Cu and CN-Fe, respectively. The total organic carbon (TOC) removal reached the highest value of 14.46% with CN-Fe.     

Preparation of Cu nanoparticles on carbon nanotubes by solution infusion method and calcining in ambient atmosphere

Copper nanoparticles were synthesized using carbon nanotubes as a template. The process involved neither pre-purification nor an additional reducing agent. This method was simple and the Cu nanoparticles were uniformly loaded on the carbon nanotubes. TEM, SEM, XRD and EDX were used to examine the morphology of the Cu particles. The diameter of the carbon nanotubes is about 70-90 nm and the size of the nanoparticles is about 50-70 nm.     

An efficient method for decoration of the multiwalled carbon nanotubes with nearly monodispersed magnetite nanoparticles

A one-pot method has been developed to prepare magnetite nanoparticles decorated carbon nanotubes (CNTs) by thermal decomposition of iron chloride on CNTs templates in diethylene glycol. The morphological and structural characterizations indicate that magnetite nanoparticles are coated on the surfaces of the CNTs to form CNT-based nanocomposites. The density of magnetite nanoparticles on CNTs could be easily tuned by adjusting the weight ratio of iron chloride to CNTs. Magnetic measurements showed that the nanocomposites are superparamagnetic at room temperature and the magnetic properties of the samples can also be tuned by adjusting preparing conditions. The nanocomposites can be readily dispersed in water to form a stable solution and can be manipulated using an external magnetic field. As-synthesized nanocomposites may have potential applications in target–drug delivery, detection and separations, and in clinical diagnosis.     

Room-temperature ferromagnetism in doped face-centered cubic fe nanoparticles

The magnetism of Fe and its alloys has been at the center of scientific and technological interest for decades. Along with the ferromagnetic nature of body-centered cubic Fe, the magnetic properties of face-centered cubic (fcc) Fe have attracted much attention. It is well known that fcc Fe is thermodynamically unstable at ambient conditions and not ferromagnetic. Contrary to what is known, we report that elongated nanoparticles of fcc Fe, grown within graphitic nanotubes, remain structurally stable and appear ferromagnetic at room temperature. The magnetic moment (2+/-0.5 microB) in these nanoparticles and the hyperfine fields for two different components of 57Fe (33 and 21 T), measured by M?ssbauer spectroscopy, are explained by carbon interstitials in the expanded fcc Fe lattice, that is, FeC(x) where x approximately 0.10, which result in the formation of a dominant Fe4C stoichiometry. First-principles calculations suggest that the ferromagnetism observed in the fcc Fe is related to both lattice expansion and charge transfer between iron and carbon. The understanding of strain- and dopant-induced ferromagnetism in the fcc Fe could lead to the development of new fcc Fe-based alloys for magnetic applications.