碳纳米管/高分子复合导电材料的研究进展

从碳纳米管的电性质出发,对以它为填料的导电性复合材料的制备方法和研究进展进行了综述,同时简单介绍了导电性复合材料电性质转变现象的理论分析模型,最后对碳纳米管/高分子复合导电材料的研究前景作了一定探讨。     

Trifluoromethyl‐Radical‐Mediated Carbonylation of Alkanes Leading to Ethynyl Ketones

The carbonylation of alkanes 1 under radical‐reaction conditions was examined by using ethynyl triflone A as the unimolecular chain‐transfer (UMCT) reagent. Good to moderate yields of ethynyl ketones 2 were prepared by means of this three‐component coupling reaction. Higher CO pressures as well as lower concentrations of triflone A improved the efficiency of the reaction over the direct addition, the latter leading to alkylated ethynes 3 . In contrast to the reaction with A , the reaction of cyclohexane ( 1a ) with allyl triflone B (= ethyl 2‐methylene‐3‐[(trifluoromethyl)sulfonyl]propanoate) in the presence of CO gave a mixture of carbonylation products, including 8a formed from two molecules each of cyclohexane, CO, and allyl triflone B .     

Electrically conducting electrospun silk membranes fabricated by adsorption of carbon nanotubes

We present a simple method of obtaining electrically conducting electrospun silk non-woven membranes consisting of nanofibers with multi-walled carbon nanotubes (MWCNTs) adsorbed on their surface. Nanofibrous membranes with fibroin diameters of 460 ± 40 nm were formed from aqueous Bombyx mori fibroin solution by electrospinning. The MWCNTs adhered well to the surface of the highly porous silk nanofibrous membranes when Triton X-100 was used as the surfactant for the dispersion of the MWCNTs in aqueous media. The electrical conductivity of the membranes was 2.4 × 10⁻⁴ S/cm due to the presence of the MWCNTs on their surface. In addition, the strong interaction between the MWCNTs and nanofibers keeps them from separating each other, even after ultrasonication. The combination of the high conductivity of the membranes and the simple process used to fabricate them could lead to significant advances in the development of new materials, such as electromagnetic interference shielding or electrostatic dissipation membranes.     

Renewable sol-gel carbon ceramic electrodes modified with a Ru-complex for the amperometric detection of l-cysteine and glutathione

A renewable three-dimensional chemically modified carbon ceramic electrode containing Ru [(tpy)(bpy)Cl] PF₆ was constructed by sol-gel technique. It exhibits an excellent electro-catalytic activity for oxidation of l-cysteine and glutathione at pH range 2-8. Cyclic voltammetry was employed to characterize the electrochemical behavior of the chemically modified electrode. The electrocatalytic behavior is further exploited as a sensitive detection scheme for l-cysteine and glutathione by hydrodynamic amperometry. Optimum pH value for detection is 2 for both l-cysteine and glutathione. The catalytic rate constants for l-cysteine and glutathione were determined, which were about 2.1×10³ and 2.5×10³ M⁻¹ s⁻¹, respectively. Under the optimized condition the calibration curves are linear in the concentration range 5-685 and 5-700 μM for l-cysteine and glutathione determination, respectively. The detection limit (S/N=3) and sensitivity is 1 μM, 5 nA/μM for l-cysteine and 1 μM, 7.8 nA/μM for glutathione. The relative standard deviation (RSD) for the amperogram's currents with five injections of l-cysteine or glutathione at concentration range of linear calibration is <1.5%. The advantages of this amperometric detector are: high sensitivity, good catalytic effect, short response time (t<3 s), remarkable long-term stability, simplicity of preparation and reproducibility of surface fouling (RSD for six successive polishing is 3.31%). This sensor can be used as a chromatographic detector for analysis of l-cysteine and glutathione.     

一种制备大量氧化锌纳米管的简单方法(英)

ZnO nanotubes were synthesized in large scale by thermal decomposition of the precursors obtained via chemical reaction between Zn(CH₃COO)₂·2H₂O and NaHCO₃ in the presence of surfactant sodium dodecyl sulfate (SDS). The inner diameters of the tubes were in the range of 80～100 nm, and outer diameters in the range of 160～260 nm with lengths up to a few micrometers. The products were characterized with XRD, TEM, and SEM.     

N-TiO2/ZnO复合纳米管阵列的掺杂机理及其光催化活性

以ZnO纳米柱阵列为模板, 采用溶胶-凝胶法制备出TiO2/ZnO和N掺杂TiO2/ZnO的复合纳米管阵列. 扫描电镜(SEM)、X射线光电子能谱(XPS)和紫外-可见漫反射吸收光谱(UV-Vis)的结果表明: 两种阵列的纳米管均为六角形结构, 直径约为100 nm, 壁厚约为20 nm; 在N-TiO2/ZnO复合纳米管阵列中, 掺入的N离子主要是以N-Ox、N-C和N-N的形式化学吸附在纳米管表面, 仅有少量的N离子以取代式掺杂的方式占据TiO2晶格O的位置; 表面N物种形成的表面态能级和取代式掺杂导致带隙的窄化, 增强了纳米管阵列的光吸收效率, 促进了光生载流子的分离. 光催化实验结果表明, N离子的掺杂有利于N-TiO2/ZnO复合纳米管阵列光催化活性的提高.     

碳纳米管电极超大容量离子电容器交流阻抗特性

采用碳纳米管作为超大容量离子电容器的电极材料,应用交流阻抗频谱法,研究了超大容量离子电容器的频率响应特性.结果表明,用碳纳米管块作电极,超大容量离子电容器在频率250 mHz以下出现“电荷饱和”；而用活性炭块作电极, 超大容量离子电容器在频率为100 mHz时仍未出现“电荷饱和”,这说明碳纳米管电极超大容量离子电容器的频率响应特性优于活性炭电极超大容量离子电容器的频率响应特性.上述两类超大容量离子电容器的阻抗谱中均出现倾角约为45°的直线段,其相位角均远小于理想电容器的相位角90°.     

Comparative EIS study of a paste electrode containing zinc powder in neutral and near neutral solutions

The corrosion and passivation of Zn powder particles dispersed in a paste electrode immersed in 0.5 M Na₂SO₄ and 5×10^–3 M Na₂HPO₄ solutions were studied mainly by electrochemical impedance spectroscopy. The role played by diffusion in the mechanism of anodic oxidation of zinc powder particles has been shown. It was demonstrated that the anodic reactionof Zn powder in neutral or near neutral media involves at least two adsorbed intermediates. By simulating the porous structure of the electrode, some information about porous nature of zinc electrode could be extracted. Electronic Publication     

A new approach to the design of surface treatments for reinforcing agents

A new approach for design of improved interfacial bonding between carbon fibers and polymeric matrices is described. In this method the affinity of surface-treated carbon fibers to various polymer matrices is simulated by analyzing the adsorption characteristics of model compounds, typical of the polymer units, onto very high surface area carbon fibers. The affinity can be evaluated by the use of Thermogravimetric Analysis (TGA) to measure adsorption–desorption characteristics. Since high surface area, activated carbon fibers (ACF) can be chemically treated to obtain acidic, basic, nonpolar or highly polar surfaces, it should be possible to assess the interactions of chemically modified surfaces with model compounds such as methanol (MeOH), acetone, dimethylformamide (DMF), dimethylether, tetrahydrofuran (THF) and water. Some preliminary results are presented, indicating that surface treatments for carbon fibers other than oxidation may lead to enhanced bonding with polymeric matrices.     

聚苯胺修饰超微盘电极上镉(Ⅱ)的表面络合吸附波

用直径7 μm的碳纤维组合成超微圆盘电极,以聚苯胺修饰电级.以阶梯扫描法、循环伏安法、双阶跃计时电量法和交流阻抗法等,研究了Cd2＋在该电极上的表面络合吸附特性和电极过程.在循环伏安图上出现两个还原峰,实验和理论都证明,由于电极表面的聚苯胺对Cd2＋的特性吸附,形成电活性的表面吸附态络合物.因此,这种表面络合物首先被还原,形成峰电位－0.90 V处的表面络合吸附波,还原峰电位比Cd2＋直接还原电位（－0.98 V）正移,循环反扫时,氧化波无峰形.根据实验数据推测了电极过程的反应机理,证实该还原波具有扩散和表面反应同时控制的表面络合吸附波的特性.理论计算与实验基本一致,并求得了表面吸附态配合物的形成常数、吸附量和表面络合反应的动力学参数.实验还证实,在峰电位－1.06 V 处的还原波,是Cd2＋的表面吸附还原态诱导而产生的催化氢波.