碳纳米管纯化对Pt/CNTs催化甲醇电化学氧化活性的影响

探索了一种适用于 Pt/CNTs催化剂的纯化方法 .利用比表面积测定、 X射线衍射 ( XRD)、透射电子显微镜 ( TEM)和电化学等手段进行了表征 .研究结果表明 ,经该方法纯化的 CNTs作为载体制备的阳极催化剂表现出明显优于相应的混酸氧化法纯化的 CNTs为载体的催化剂催化性能

A novel approach to Co/CNTs catalyst via chemical vapor deposition of organometallic compounds

A novel approach for attaching well-dispersed cobalt nanoparticles homogeneously onto carbon nanotubes via metal organic chemical vapor deposition technique is reported. The obtained Co/CNTs catalysts feature a narrow size distribution of Co particles centering around 7.5 nm, and show high activity and regioselectivity for hydroformylation of 1-octene.

Laser-surface-alloyed carbon nanotubes reinforced hydroxyapatite composite coatings

Carbon-nanotube sCNTd-reinforced hydroxyapatite composite coatings have been fabricated by laser surface alloying. Microstructural observation using high-resolution transmission electron microscopy showed that a large amount of CNTs remained with their or

Kinetics of Glass Transition and Crystallization in Carbon Nanotube Reinforced Mg-Cu-Gd Bulk Metallic Glass

Mg65 Cu25 Gdlo bulk metallic glass and its carbon nanotube reinforced composite were prepared. Differential scanning calorimeter (DSC) was used to investigate the kinetics of glass transition and crystallization processes. The influence of CNTs addition to the glass matrix on the glass transition and crystallization kinetics was studied. It is shown that the kinetic effect on glass transition and crystallization are preserved for both the monothetic glass and its glass composite. Adding CNTs in to the glass matrix reduces the influence of the heating rate on the crystallization process. In addition, the CNTs increase the energetic barrier for the glass transition. This results in the decrease of GFA . The mechanism of the GFA decrease was also discussed.

Wear Studies of Hydroxyapatite Composite Coating Reinforced by Carbon Nanotubes

Multi-walled carbon nanotubes (CNTs) have been successfully introduced into hydroxyapatite (HA) coatings using laser surface alloying. It is evident from transmission electron microscopy (TEM) observations that the CNTs present in the matrix still keep their multi-walled cylinder graphic structure, although they undergo the laser irradiation. Scratching test results indicated that the as-alloyed HA composite coatings exhibit improved wear resistance and lower friction coefficient with increasing the amount of CNTs in the precursor material powders. These composites have potential applications in the field of coating materials for metal implants under high-load-bearing conditions. (c) 2006 Elsevier Ltd. All rights reserved.

碳纳米管-Mg_(65)Cu_(25)Gd_(10)非晶复合材料玻璃转变的动力学性质

制备了Mg65Cu25Gd10大块非晶合金及其碳纳米管(CNTs)复合材料,对两种材料进行了不同扫描速率下的差热扫描量热分析,研究了加入CNTs对材料玻璃转变和晶化动力学效应的影响。结果表明:加入CNTs后,复合材料的玻璃转变和晶化行为仍然具有动力学效应,但加入的CNTs减小了材料晶化行为对升温速率的依赖程度;同时,加入CNTs加大了材料发生玻璃转变时需要克服的能量势垒,增大了峰值温度时的晶化反应速率常数,从而降低了材料的玻璃形成能力(GFA);对CNTs降低GFA的原因也进行了探讨。

微/纳米氧化锌（ZnO）的生长、性质及其应用研究

纳米氧化锌（ZnO）是一种直接宽带隙半导体材料，室温下其禁带隙宽为本3.37 eV，激子束缚能为60 meV。纳米ZnO有明显的尺寸效应、表面和界面效应等，物理化学性能优越。在压电材料、铁电材料、平面显示、表面声波、传感器、场发射器件、激光、光催化等方面有着广泛的用途。近年来，对纳米ZnO材料的研究成为国内外的一个热点。 本论文研究了用化学气相沉积（CVD）法制备微/纳米ZnO材料。通过控制实验条件，合成了多种特殊结构和形貌的微/纳米ZnO材料，并用扫描电子显微镜（SEM）、高分辨率透射电镜（HR-TEM）、X-射线衍射仪（XRD）、Raman光谱和光致发光（PL）等对材料的结构和光学性能进行了表征。采用CVD法，在温度为630 °C，氧气流量为15 sccm，氩气流量为300 sccm的条件下，制备了一种纳米带冠四足状ZnO（T-ZnO）。此结构ZnO材料的每根足顶端均有一规则的六方帽形结构，具有很大的比表面积。实验结果表明：合成的ZnO材料为纤维锌矿结构单晶，并且沿着(0001)方向生长；室温下的PL谱有两个激发峰，一个是在393 nm处相对较弱的近带紫外峰，另一个是在511 nm处强峰。而材料在600 °C下氧气中退火30 min后，511 nm附近的绿光激发辐射峰则基本消失了，这说明在511 nm处的绿光激发辐射峰可能是由于氧空位引起的。此外，通过改变实验条件，还得到了其他多种结构的微/纳米ZnO材料。 通过大量实验，找到了一种在低温下合成微/纳米ZnO材料的新方法，即水蒸气氧化法。用ZnI2作为锌源，水蒸气作为氧化剂，实验温度在300～500 °C范围内，大大低于通常CVD法的500～1500 °C。采用此法，用硅做基底，得到了一系列有趣的实验结果，大多数情况下ZnO纳米晶自组装成很规则的圆。而在瓷舟中收集到的纳米ZnO跟普通CVD法结果相似，可以得到锥状、棒状等结构的纳米晶，但其生长方式与硅基底上的有很大差别。此外，用水蒸气氧化法，还实现了ZnO纳米晶在碳纳米管（CNTs）上的直接生长，而且其PL性能增强，这可能是纳米ZnO和CNTs相互耦合的结果。在700 °C温度下，以锌粉和ZnI2作为锌源，用水蒸气作为氧化剂，在硅基底的正反面分别得到了纳米棒和纳米推子阵列。此外，还对水蒸气氧化法的化学反应机理进行了分析，实验结果证明：固态ZnI2在受热和一定真空度下先蒸发成ZnI2分子，ZnI2分子遇到水蒸气发生反应生成偶极ZnO分子，这些ZnO偶极分子在硅基底上通过静电力自组装成特殊的几何形状。 此外，还通过分子动力学模拟的方法，对材料的力学性能进行了研究，得到了ZnO的弹性常数和体弹性模量，模拟值跟其他研究人员的实验和模拟结果吻合得很好，并估出算了ZnO晶体的表面能和断裂韧性。 本论文还对制备材料的光催化性能进行了系统的研究，采用CVD法制备ZnO，对铬黑T（EBT）进行光催化降解实验。通过正交实验方法，得到了ZnO催化降解EBT的最佳工艺条件，即催化剂用量为5 g/L，光照强度为120 W，反应温度为20 °C，反应时间为120 min，EBT浓度为10 mg/L，溶液pH值为4。 在最佳实验条件下，20分钟内有95%的EBT被降解完，30分钟内则全部降解。因此，ZnO在EBT的降解中催化效率很高，在废水处理中具有潜在的应用前景。

Prediction of Effective Moduli of Carbon Nanotube-Reinforced Composites with Waviness and Debonding

Carbon nanotubes (CNTs) have been regarded as ideal reinforcements of high-performance composites with enormous applications. However, the waviness of the CNTs and the interfacial bonding condition between them and the matrix are two key factors that influence the reinforcing efficiency. In this paper, the effects of the waviness of the CNTs and the interfacial debonding between them and the matrix on the effective moduli of CNT-reinforced composites are studied. A simple analytical model is presented to investigate the influence of the waviness on the effective moduli. Then, two methods are proposed to examine the influence of the debonding. It is shown that both the waviness and debonding can significantly reduce the stiffening effect of the CNTs. The effective moduli are very sensitive to the waviness when the latter is small, and this sensitivity decreases with the increase of the waviness. (C) 2008 Elsevier Ltd. All rights reserved.

A comparative study of Young's modulus of single-walled carbon nanotube by CPMD, MD, and first principle simulations

Carbon nanotubes (CNTs), due to their exceptional magnetic, electrical and mechanical properties, are promising candidates for several technical applications ranging from nanoelectronic devices to composites. Young's modulus holds the special status in material properties and micro/nano-electromechanical systems (MEMS/NEMS) design. The excellently regular structures of CNTs facilitate accurate simulation of CNTs' behavior by applying a variety of theoretical methods. Here, three representative numerical methods, i.e., Car-Parrinello molecular dynamics (CPMD), density functional theory (DFT) and molecular dynamics (MD), were applied to calculate Young's modulus of single-walled carbon nanotube (SWCNT) with chirality (3,3). The comparative studies showed that the most accurate result is offered by time consuming DFT simulation. MID simulation produced a less accurate result due to neglecting electronic motions. Compared to the two preceding methods the best performance, with a balance between efficiency and precision, was deduced by CPMD.

High-Strength Composite Fibers: Realizing True Potential of Carbon Nanotubes in Polymer Matrix through Continuous Reticulate Architecture and Molecular Level Couplings

Carbon nanotubes have unprecedented mechanical properties as defect-free nanoscale building blocks, but their potential has not been fully realized in composite materials due to weakness at the interfaces. Here we demonstrate that through load-transfer-favored three-dimensional architecture and molecular level couplings with polymer chains, true potential of CNTs can be realized in composites as Initially envisioned. Composite fibers with reticulate nanotube architectures show order of magnitude improvement in strength compared to randomly dispersed short CNT reinforced composites reported before. The molecular level couplings between nanotubes and polymer chains results in drastic differences in the properties of thermoset and thermoplastic composite fibers, which indicate that conventional macroscopic composite theory falls to explain the overall hybrid behavior at nanoscale.

直接甲醇燃料电池阳极催化剂及甲醇氧化稀土助催化剂剂研究

燃料电池以其高效、环境友好的发电方式，被誉为21世纪的能源技术。其中，直接甲醇燃料电池（DMFC）更以燃料甲醇来源丰富，价格低廉，储存、携带方便而成为近年的研究热点。但是，DMFC在其实用化之前还需要解决一些重要问题，其中的关键之一就是高性能的贵金属催化剂的研究。我们知道，甲醇的电化学活性要低于氢气三个数量级；而且甲醇在R表面进行电化学氧化时，其中间解离吸附产物会造成贵金属催化剂中毒，显著降低了催化剂的活性。因此，要使DMFC具有相当高的电流密度和运行稳定性，就需要对贵金属催化剂制备进行不断的研究和改进。在本文的工作中，主要从Pt/C催化剂的制备方法、新型碳纳米管载体、稀土助催化剂等三个方面进行了研究和探索，取得的具体结果如下：1．Pt／C催化剂制备方法的研究与改进（1）在本组已有的研究结果基础上，对预沉积还原法进行了一些改进，采用原子吸收光谱（AAS）进行表征，发现Pt的利用率得到了明显的提高。采用X射线衍射。（RD）、透射电子显微镜（TEM）和BET表征铂的粒径、晶态结构和催化剂特性，分析表明，经过改进的预沉积还原法制备的催化剂仍然具有良好的分散性、较小的粒径、较低的晶态结构和良好的催化剂特性，电化学测试证明其性能要优于同等的E-TEK催化剂。（2）借鉴冶金学中的相关技术，提出了一种新的Pt/C催化剂制备方法一程序升温焙烧法。该方法的具体步骤增强了金属催化剂粒子和碳载体之间的相互作用力，提高了碳载体的导电性，并且形成了部分有利于催化反应进行的活性晶态结构。得到的R／C催化剂获得了近似E-TEK催化剂的催化活性，在具体方法上仍有改进的潜力。采用了同（1）的催化剂表征方法。2．甲醇电化学氧化稀土助催化剂研究在直接甲醇燃料电池Pt/C催化剂的研究过程中，一个重要的方面就是助催化剂的研究，并且已经得到了较好的结果。本工作选用了稀土元素为研究对象，因为稀土元素属于过渡金属，具有丰富的d电子轨道，易于和金属形成强的类化学键的吸附作用，并且能够和有机小分子形成多种配位化合物。经过初步的工作，发现了有些稀土离子如Sm3+能够在Pt表面吸附并且对甲醇电化学氧化具有较稳定的促进作用，采用循环伏安法，计时电流，交流阻抗等电化学方法进行了表征。根据实验结果，对其反应机理进行了初步的探讨。3．碳纳米管（CNTs）作为贵金属催化剂载体的研究碳纳米管（CNTs）由于其结构上的特殊性（径向尺寸为纳米量级，轴向尺寸为微米量级）而表现出典型的一维量子材料，同时具有较高的机械强度和超常的电学性能，能够为化学反应提供纳米级的反应场所，因此受到了化学界包括电化学研究人员的极大关注。已经在作为贵金属催化剂载体方面进行了一些研究，本工作的主要内容就是针对Pt/CNTs催化剂对碳纳米管的要求，对其预处理方法进行了改进，采用了如（1）中的催化剂表征方法和（2）中的相关电化学方法进行测定，发现碳纳米管作为贵金属催化剂载体时，对它的纯化处理方法的不同明显地影响了其载体性质和催化剂的活性。

电化学方法检测DNA碳纳米管修饰电极

在碳纳米管(CNTs)修饰玻碳(GC)后得到CNTs/GC电极的基础上,分别用吸附法和共价键合法制备了脱氧核糖核酸(DNA)修饰的CNTs/GC电极。以硫堇(Th)为电化学指示剂,用循环伏安、示差脉冲伏安、交流阻抗法等测试技术对制备的修饰电极进行了电化学表征。结果表明,用共价键合法制备的DNA修饰的CNTs电极上DNA的固定量多、稳定性好。制备的DNA修饰电极可用于电化学基因传感器等领域。

A solid-state dye-sensitized solar cell based on a novel ionic liquid gel and ZnO nanoparticles on a flexible polymer substrate

This paper describes a new strategy to make a full solid-state, flexible, dye-sensitized solar cell (DSSC) based on novel ionic liquid gel, organic dye, ZnO nanoparticles and carbon nanotube (CNT) thin film stamped onto a polyethylene terephthalate (PET) substrate. The CNTs serve both as the charge collector and as scaffolds for the growth of ZnO nanoparticles, where the black dye molecules are anchored.

厚壁和薄壁碳纳米管载Pt催化剂制备和对甲醇氧化的电催化活性

制备了壁厚约5 nm、管径为140~220 nm薄壁碳纳米管(CNTs)和壁厚约50 nm,管径为80~200 nm厚壁碳纳米管。研究了浓HNO3处理对不同壁厚CNTs结构和表面基团的影响。结果表明,经硝酸处理后,厚壁CNTs的双电层充放电电量(Qd)和表面含氧基团氧化所需电量(Qo)分别增加了1.34和0.098 mC,薄壁CNTs的Qd和Qo分别增加了5.69和0.175 mC。表明与厚壁CNTs相比,薄壁CNTs易被切断,表面碳原子易被氧化。当用常规液相还原法将Pt粒子沉积在薄壁和厚壁CNTs上后,由于浓HNO3处理过的薄壁CNTs具有大的比表面积和多的含氧基团,Pt粒子更容易均匀的吸附在薄壁CNTs表面,因此,制得的Pt/CNTs催化剂对甲醇氧化有很高的电催化活性。