生长温度对碳纳米管阴极场发射性能的影响

碳纳米管(Carbon Nanotubes,CNTs)场发射平面显示器(Field Emission Display,FED)与其他显示器比较显示了其独特优点,被认为是未来理想的平面显示器之一。碳纳米管阴极作为器件的核心部分,其性能的好坏直接影响显示器的性能。针对30~60英寸(76.2~152.4cm)大屏幕显示器所用的厚膜工艺,即采用丝网印刷法制备了碳纳米管阴极阵列,研究了化学气相沉积法在不同温度下生长的CNTs的场发射电流-电压特性,找到了适合FED用碳纳米管的最佳生长温度。结果表明生长温度越高(750℃),CNTs场发射性能越好。并用荧光粉阳极测试这些CNTs的场发射发光显示效果,验证了上述结论。     

Low Dimension Semiconducting Composite Nanomaterials

Recently, low dimension nanostructures have gained considerable attention due to their technological potential as unique types of nanoscale building blocks for future optoelectronic devices and systems. Semiconducting composite nanomaterials, which can combine the advantages of two or more components, have been the focus in the area of nanomaterials synthesis and device application.In this paper, we report our work on the preparation of composite nanomaterials based on CNTs.CNTs were coated by organic or inorganic species via novel and facile methods (Fig. 1 and Fig.2).These functional CNTs based composites show eminent prospects and opportunities for new applications in a wide variation of areas.     

碳纳米管的共价修饰

碳纳米管(carbon nanotubes, CNTs)的溶解性和分散性较差是目前制约其广泛应用及在一些有特殊要求的领域(如生物技术)应用的主要原因之一. 对CNTs进行共价修饰是改善其溶解性和分散性的有效方法之一. 目前CNTs的共价修饰主要通过两类反应来实现: 羧基的衍生反应和直接加成反应. 介绍了基于这两种反应的几种共价修饰方法, 比较了各种修饰方法的优缺点及其对CNTs的溶解性和分散性的改善效果.     

利用无水乙醇分解制备碳纳米管

利用CVD法高温分解无水乙醇,以分子筛（合成皂石）基体上的Fe颗粒为催化剂,制备出了管壁更薄、端部为开口结构的碳纳米管.本实验制备出的碳纳米管,相对于传统CVD方法制备出的碳纳米管,在实验条件控制稳定的情况下,管壁较直、缺陷较少、管内径较大.具有这样结构的碳纳米管在储氢等方面应具备更为优良的效果,从而有着潜在的应用前景.     

Effect of transition metals (Cr, Mn, Fe, Co, Ni and Cu) on selective hydrogenation of cinnamaldehyde over Pt/CNTs catalyst

Summary The effect of transition metals (Cr, Mn, Fe, Co, Ni and Cu) on the selective hydrogenation of cinnamaldehyde (CMA) to the corresponding semi-hydrogenated product over Pt/CNTs catalyst has been studied in ethanol at 343 K under 2.0 MPa H₂ pressure. PtNi/CNTs catalyst shows good catalytic activity and selectivity of C=C bond hydrogenation, 68.4% for conversion of CMA and 97.0% for selectivity of hydrocinnamaldehyde (HCMA). PtCo/CNTs catalyst shows good catalytic activity and selectivity of C=O bond hydrogenation, 91.3% for conversion of CMA and 88.2% for selectivity of cinnamylalcohol (CMO).     

Amperometric glucose biosensor based on electrodeposition of platinum nanoparticles onto covalently immobilized carbon nanotube electrode

A new amperometric biosensor for glucose was developed based on adsorption of glucose oxidase (GOx) at the gold and platinum nanoparticles-modified carbon nanotube (CNT) electrode. CNTs were covalently immobilized on gold electrode via carbodiimide chemistry by forming amide linkages between carboxylic acid groups on the CNTs and amine residues of cysteamine self-assembled monolayer (SAM). The fabricated GOx/Au_nano/Pt_nano/CNT electrode was covered with a thin layer of Nafion to avoid the loss of GOx in determination and to improve the anti-interferent ability. The immobilization of CNTs on the gold electrode was characterized by quartz crystal microbalance technique. The morphologies of the CNT/gold and Pt_nano/CNT/gold electrodes have been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the gold, CNT/gold, Pt_nano/gold and Pt_nano/CNT/gold electrodes has also been studied by amperometric method. In addition, effects of electrodeposition time of Pt nanoparticles, pH value, applied potential and electroactive interferents on the amperometric response of the sensor were discussed.

The enzyme electrode exhibited excellent electrocatalytic activity and rapid response for glucose in the absence of a mediator. The linear range was from 0.5 to 17.5 mM with correction coefficient of 0.996. The biosensor had good reproducibility and stability for the determination of glucose.     

碳纳米管结构对碳纳米管载Pt催化剂电催化性能的影响

在制备单、双壁及不同管径的多壁碳纳米管(CNTs)的基础上, 用液相还原法把Pt沉积到单、双壁和管径不同的多壁CNTs上. 发现制得的CNTs载Pt(Pt/CNTs)催化剂对甲醇氧化的电催化活性随CNTs管径减小而增加. 这归结于管径小的CNTs的比表面积较大, 含氧基团多, 有利于提高Pt粒子分散度, 加上管径小的单壁CNTs具有更高的导电性, 这些因素都有利于提高Pt/CNTs催化剂对甲醇氧化的电催化活性.     

Strain rate effects on compressive behavior of covalently bonded CNT networks

In this study, strain rate effects on the compressive mechanical properties of randomly structured carbon nanotube (CNT) networks were examined. For this purpose, three-dimensional atomistic models of CNT networks with covalently-bonded junctions were generated. After that, molecular dynamics (MD) simulations of compressive loading were performed at five different strain rates to investigate the basic deformation characteristic mechanisms of CNT networks and determine the effect of strain rate on stress–strain curves. The simulation results showed that the strain rate of compressive loading increases, so that a higher resistance of specimens to deformation is observed. Furthermore, the local deformation characteristics of CNT segments, which are mainly driven by bending and buckling modes, and their prevalence are strongly affected by the deformation rate. It was also observed that CNT networks have superior features to metal foams such as metal matrix syntactic foams (MMSFs) and porous sintered fiber metals (PSFMs) in terms of energy absorbing capabilities.     

Thermal stability,morphology and electronic band gap of Zn(NCN)

The thermal behavior of zinc carbodiimide Zn(NCN) was examined in the temperature range between 200 and 1100 °C in Ar atmosphere. The material starts to partially decompose at about 800 °C. Heat treatment at temperatures beyond 800 °C results in the formation of the byproducts nitrogen-containing bamboo-like multiwall carbon-nanotubes of 20–50 nm in diameter due to a partial decomposition of Zn(NCN) into dicyan (CN)₂, zinc and nitrogen gas followed by the polymerization of the former product to paracyanogen (CN)_n. At 1100 °C, the yield of the residual carbodiimide depends on the dwelling time and the initial amount of powder used for pyrolysis. One hour dwelling at 1100 °C yields ∼50% of the Zn(NCN) separated as pure material. Temperature-induced change in the band structure, namely indirect-to-direct band gap transition, is registered when compared the Zn(NCN) at room temperature with the residual material annealed at 1100 °C. The transition from indirect (E_g = 4.32 eV) to direct band gap (E_g = 4.93 eV) is due to the thermal annealing process which results in healing of crystal defects.     

Enhanced dielectric and electro-optical properties of a newly synthesised ferroelectric liquid crystal material by doping gold nanoparticle-decorated multiwalled carbon nanotubes

In this article, a newly synthesised ferroelectric liquid crystal (FLC) material, namely LAHS 22, has been characterised. The characterisation of the FLC material has been performed using dielectric relaxation spectroscopy, differential scanning calorimetry and polarisation optical microscopy. We observed an enhancement in the dielectric and electro-optical properties of the FLC material by incorporating gold nanoparticles (GNPs)-decorated multiwalled carbon nanotubes (MWCNTs). The GNPs-decorated MWCNTs cause an increment in dielectric dispersion (up to kHz), absorption, spontaneous polarisation and rotational viscosity of the FLC material. The pure and GNPs-decorated MWCNTs doped FLC cells were analysed by means of various dielectric spectroscopic and optical measurements. The observed enhancement in the dielectric and electro-optical properties of the FLC material has also been studied with concentration of GNPs-decorated MWCNTs in FLC material. The GNPs-decorated MWCNTs/FLC composites are not only of fundamental importance, but also useful materials for device applications such as liquid crystal displays and memory devices.