Pt/WC-CNTs催化剂的制备及其对氧还原的电催化性能

通过表面修饰和还原碳化技术制备了以WC为主相的碳化钨/碳纳米管材料（WC-CNTs）,并进一步采用微波多元醇法载铂制备复合催化剂Pt/WC-CNTs。该催化剂相比于Pt/CNTs催化剂,具有更低的过电位、更大的电流密度和交换电流密度,且具有更小的电荷转移电阻和更好的氧还原选择性,显示了优异的氧还原电催化性能。XRD结果表明催化剂由多晶面的WC、Pt晶粒和CNTs组成,TEM和HRTEM显示细小的Pt颗粒均匀地分布在WC-CNTs表面。Pt颗粒和WC颗粒紧密接触,这有利于它们之间的催化协同效应,从而大大增强了Pt的氧还原催化活性。旋转圆盘电极研究结果表明Pt/WC-CNTs催化剂对氧还原反应为直接四电子过程。碳化钨/碳纳米管载铂催化剂性能优异、成本较低,在燃料电池阴极催化剂的研究应用中具有良好的发展前景。     

碳纳米管聚氨酯复合材料的制备及其性能研究

将多壁碳纳米管超声分散后,利用直接共混法将分散液与水性聚氨酯混合,使其在平板上流延并烘干成膜,通过扫描电子显微镜(SEM)和X-射线衍射仪(XRD)对该材料的结构和性能进行表征,测定其透光率及抗张强度等,对该材料的性能进行了系统的研究.研究结果表明碳纳米管能够在聚氨酯中分散开,且碳纳米管能够很好的实现对聚氨酯的增强和增韧.     

碳纳米管表面改性及其应用于复合材料的研究现状

对碳纳米管进行表面改性可提高碳纳米管的表面活性、分散能力和与基体材料之间的相容性,从而提高其在复合材料中的增强效果。本文介绍了碳纳米管表面改性的方法,分为物理法和化学法,物理法主要有高能机械研磨法、高能球磨法和超声振动法;化学法主要有酸处理法、偶联剂法、化学镀法、高能射线辐照法和原子转移自由基聚合法。在实际应用中常将几种改性方法联合使用,使得到的改性产物性能更稳定,性质更多样化。同时,介绍了改性后的碳纳米管在各种复合材料中的应用现状。并指出了对碳纳米管进行改性的两个重点：一是尽量保持碳纳米管的本身结构完整性;二是提高碳纳米管在基体中的分散性。     

碳纳米管水平阵列的结构控制生长：进展与展望

碳纳米管水平阵列是指生长于平整基底上且与沿基底平行排列的一种碳纳米管类型。与其他类型的碳纳米管相比,水平阵列类型的碳纳米管具有很低的结构缺陷和优异的力学、电学、热学性能,在微电子、超强纤维、航空航天等尖端领域有广阔和重要的应用前景。这些应用对碳纳米管的缺陷浓度、手性分布、半导体型纯度及阵列密度等指标的要求十分严苛,因而碳纳米管水平阵列的结构控制与批量制备是其实现性能应用的关键。在过去的近三十年中,研究者们已在碳纳米管水平阵列的结构控制生长上取得了大量进展,但同时也面临不少挑战。本文对碳纳米管水平阵列的结构控制、批量制备及前沿应用的研究进展进行了回顾,并对其面临的挑战和未来发展方向进行了讨论。     

环氧树脂/碳纳米管复合材料制备及导电性能研究进展

简要介绍了环氧树脂/碳纳米管复合材料的组成以及碳纳米管在环氧树脂中的分散方法;综述了环氧树脂/碳纳米管复合材料的制备方法,包括溶液浇铸法、原位聚合法、化学改性法、混合固化剂辅助叠层法和树脂传递模塑法;总结了国内外对环氧树脂/碳纳米管复合材料导电性能的研究现状,并分析了影响其导电性能的因素,包括碳纳米管的比表面积、表面功能化和制备方法,剪切速率及固化条件等。     

制备碳纳米管和碳洋葱所用催化剂研究进展

为借鉴定向生长碳纳米管的方法来实现碳洋葱尺寸可控的周期性阵列生长,基于碳纳米管和碳洋葱会相伴相随产生,文章对化学气相沉积法制备碳纳米管和碳洋葱所用催化剂进行了综述,并从二者的生长机理方面探讨了彼此之间的联系,阐明了借鉴定向生长碳纳米管的方法实现碳洋葱的周期性阵列生长的可行性。     

碳纳米管阵列在电化学中的应用

高定向的碳纳米管阵列由于有优越的电导率、高比表面积、发达的多孔结构而具有良好的电化学性能如大容量、优异的速率性能和较长的循环寿命,这些独特的性质使其在电化学领域显现出巨大的应用潜力。本文简要介绍了碳纳米管阵列的制备,并从电化学储能、电化学催化和电化学传感器等领域综述近年来碳纳米管阵列在电化学应用中的最新研究进展,分析了其所面临的问题,并提出了未来碳纳米管阵列在电化学应用中的发展方向。关键词：碳纳米管阵列；电化学性能；储能；催化；传感器中图分类号：     

溶液共混法制备聚氨酯／碳纳米管复合材料及其性能

 通过强酸处理方法对碳纳米管进行改性处理并对其结构和分散稳定性进行分析。采用溶液共混法制备了聚氨 酯/碳纳米管复合材料,利用FTIR对其结构进行了分析,探讨了碳纳米管对复合材料力学性能、热稳定性能以及弹 性回复率的影响。结果表明,碳纳米管经酸处理后添加了羧酸活性基团,提高了其在溶剂中的分散性|在复合材料 中,碳纳米管以较强氢键与大分子连接,复合材料的力学性能和热稳定性能都有所提高,而弹性回复率没有受到很 大影响。     

聚氨酯/碳纳米管复合材料的制备及表征

采用原位聚合法制备了聚氨酯/碳纳米管复合材料,并利用扫描电子显微镜、傅立叶红外光谱仪对其进行了表征,同时探讨了碳纳米管对复合材料力学性能、热稳定性、弹性回复率及导电性能的影响.结果表明,经过酸处理的碳纳米管参与了聚合反应,并在基体中获得了较好的分散,同时力学性能、热稳定性及导电性都有明显的提高,而弹性回复率没有受到很大的影响.     

垂直碳纳米管阵列的生长控制研究进展

垂直碳纳米管（VACNT）阵列由于具有良好的排列、优异的导电导热能力、高比表面积、高纯度等优点而得到广泛应用。本文概述了用于碳纳米管阵列生长的热化学气相沉积（CVD）制备方法的最新进展,重点阐述了CVD法生长碳纳米管阵列的动力学与生长终止机理,指出CVD过程中的催化剂形貌演化是引发碳纳米管阵列生长停止的重要原因。介绍了人们通过生长条件控制与催化剂设计等方法调控碳纳米管阵列结构（包括管壁数、管径和密度）方面取得的进展,指出碳纳米管阵列的大批量制备及结构参数的精确调控是未来发展的 重点。     

Highly dispersed Pt nanoparticles by pentagon defects introduced in bamboo-shaped carbon nanotube support and their enhanced catalytic activity on methanol oxidation

Bamboo-shaped carbon nanotubes (BCNTs), which were synthesized through chemical vapor deposition by using cresol as the carbon source, were explored as Pt catalyst support in comparison with conventional carbon nanotubes (CNTs) and Vulcan XC carbon blacks. The pyrolysis of cresol produced a large amount of pentagon defects introduced in the walls of BCNTs, which could possess higher chemical activity and stronger interaction with metal particles. After a mild purification, the BCNTs exhibited more oxygen-containing functional groups than CNTs, as shown by Fourier transform infrared spectra and cyclic voltammetry. The formed oxygen-containing functional groups as well as the pentagon defects could act as uniform active sites for metal particle loading. By ethylene glycol reduction, highly dispersed Pt nanoparticles with a narrow size distribution of 2-3 nm were easily supported on BCNTs, as shown by transmission electron microscope. The Pt/BCNT catalyst showed higher electro-catalytic activity on the methanol oxidation than the Pt/CNT and Pt/Vulcan XC catalyst, which could be largely ascribed to the highly dispersed Pt nanoparticles due to the introduced pentagon defects in the tube-walls (comparing with Pt/CNT) and the graphitic nanotube network that could provide good electron conduction (comparing with Pt/Vulcan XC).     

炭载体对Pt-C复合物非碱性条件下催化甘油氧化性能的影响

采用等量浸渍法制备了具有相似平均粒径的活性炭（AC）和碳纳米管（CNTs）负载的Pt催化剂,并比较研究了非碱性条件下两种催化剂催化甘油氧化反应的性能。结果表明,炭载体对Pt-C复合物催化甘油氧化反应的活性、选择性和稳定性有重要影响。相对于Pt/CNTs催化剂,Pt/AC催化剂中Pt 4f结合能较低,导致其表面氧的覆盖度相对较高,因而抑制了甘油的吸附,降低了甘油氧化反应的初始活性;Pt/AC催化剂会促进甘油醛进一步氧化成甘油酸以及C₃产物的氧化断键;Pt/AC催化剂失活的主要原因是氧中毒和中间产物的吸附,而Pt/CNTs催化剂的失活主要是由于甘油酸的吸附堵塞Pt表面的活性位造成的。     

PET/碳纳米管共混物的研究进展

综述了聚对苯二甲酸乙二醇酯(PET)/碳纳米管(CNTs)的共混物的制备和性能。官能化CNTs比未官能化CNTs在PET母体中的分散性得到改善;PET/未官能化CNTs共混物和PET/官能化CNTs共混物相比PET,熔融结晶温度均增高,具有更高的结晶度;PET/未官能化CNTs共混物的熔点变化不大,而PET/官能化CNTs共混物的熔点的变化取决于官能化CNTs中引入官能团的化学结构;PET/未官能化CNTs共混物和PET/官能化CNTs共混物的熔体黏度均比PET有所提高,切力变稀行为比PET也有所增强;PET/未官能化CNTs共混物和PET/官能化CNTs共混物的热稳定性、导电性能及机械性能均得到改善。     

Formation of carbon nanotubes through ethylene decomposition over supported Pt catalysts and silica-coated Pt catalysts

Ethylene decomposition was performed over supported Pt catalysts to fabricate composites of Pt metal nanoparticles and carbon nanotubes (CNTs). All supported Pt catalysts (Pt/carbon black, Pt/CNT, Pt/MgO, Pt/Al₂O₃ and Pt/SiO₂) showed catalytic activity for ethylene decomposition at 973 K to form CNTs. Pt metal particles were found at tips of CNTs. These results indicate that Pt metal particles have catalytic activity for growth of CNTs through hydrocarbon decomposition. A broad range (5-50 nm) of CNT diameters were formed from the use of supported Pt metal catalysts although Pt metal particles in the catalysts before ethylene decomposition were relatively uniform in size (2-5 nm). These results imply that Pt metal particles in the catalysts aggregated during ethylene decomposition at 973 K. Aggregation of Pt metal particles in catalysts during ethylene decomposition could be suppressed by covering catalysts with silica layers that were a few nanometers thick. Silica-coated Pt catalysts showed high activity for ethylene decomposition to form CNTs with uniform diameters (8-10 nm) despite the uniform coverage of Pt metal particles with silica layers.     

The effect of the Pt deposition method and the support on Pt dispersion on carbon nanotubes

Carbon nanotube supported platinum (Pt/CNTs) catalysts prepared by different Pt deposition methods and on different CNT supports were studied. Colloidal based methods were demonstrated to be more effective than other wet chemistry deposition methods (e.g., impregnation and precipitation) for the preparation of highly dispersed Pt/CNTs. Pt catalyst supported on CNTs with a dispersion uniformity comparable to that supported on carbon powder was achieved using a zwitterionic surfactant 3-(N,N-dimethyldodecylammonio) propanesulfonate (SB12) as stabilizer in a monitored pH environment. It was experimentally observed that oxygen-containing surface functionalities on CNTs can greatly affect the catalyst particle dispersion by manipulating Pt anchoring and/or nucleating sites. Furthermore, it was revealed that the performance of Pt/CNTs based fuel cell is strongly dependent on the electrode fabrication method.     

Production of Carbon Nanotube by Ethylene Decomposition over Silica-Coated Metal Catalysts

Formation of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) through the decomposition of ethylene at 973 K was achieved using various metal catalysts covered with silica layers. CNFs of various diameters were formed by ethylene decomposition over a Co metal catalyst supported on the outer surface of the silica. In contrast, silica-coated Co catalysts formed CNTs with uniform diameters by ethylene decomposition. Silica-coated Ni/SiO₂ and Pt/carbon black also formed CNTs with uniform diameters, while CNFs and CNTs with various diameters were formed over Ni/SiO₂ and Pt/carbon black without a silica coating. These results indicate that silica layers that envelop metal particles prevent sintering of the metal particles during ethylene decomposition. This results in the preferential formation of CNTs with a uniform diameter.     

Hall Measurements on Carbon Nanotube Paper Modified With Electroless Deposited Platinum

Carbon nanotube paper, sometimes referred to as bucky paper, is a random arrangement of carbon nanotubes meshed into a single robust structure, which can be manipulated with relative ease. Multi-walled carbon nanotubes were used to make the nanotube paper, and were subsequently modified with platinum using an electroless deposition method based on substrate enhanced electroless deposition. This involves the use of a sacrificial metal substrate that undergoes electro-dissolution while the platinum metal deposits out of solution onto the nanotube paper via a galvanic displacement reaction. The samples were characterized using SEM/EDS, and Hall-effect measurements. The SEM/EDS analysis clearly revealed deposits of platinum (Pt) distributed over the nanotube paper surface, and the qualitative elemental analysis revealed co-deposition of other elements from the metal substrates used. When stainless steel was used as sacrificial metal a large degree of Pt contamination with various other metals was observed. Whereas when pure sacrificial metals were used bimetallic Pt clusters resulted. The co-deposition of a bimetallic system upon carbon nanotubes was a function of the metal type and the time of exposure. Hall-effect measurements revealed some interesting fluctuations in sheet carrier density and the dominant carrier switched from N- to P-type when Pt was deposited onto the nanotube paper. Perspectives on the use of the nanotube paper as a replacement to traditional carbon cloth in water electrolysis systems are also discussed.     

Catalyst-free,self-assembly,and controllable synthesis of graphene flake–carbon nanotube composites for high-performance field emission

Catalyst-free and self-assembled growth of graphene flakes (GFs) on carbon nanotube (CNT) arrays have been realized by using microwave plasma enhanced chemical vapor deposition. The shape of GFs was highly manipulated by adjusting the growth time, C concentration, and microwave power. We qualitatively discussed the nucleation and growth mechanism of GFs based on the growth parameter–GF shape studies. The field emission (FE) properties of graphene flake–carbon nanotube (GF–CNT) composites for different GF shapes were measured and found to be strongly influenced by the GF distribution. The optimal shape of GFs for FE had small scales, sharp edges, and sparse distribution on CNTs. The best FE properties with the optimal shape were observed with a low turn-on electric field of 0.73 V/μm and excellent stability, which are superior to those of the as-grown CNT arrays and GF–CNT composites covered by densely distributed GFs. We consider that the large aspect ratio of CNTs and the unique FE stability of GFs play a synergetic effect on the improved FE properties.     

Fabrication of patterned carbon nanotube thin films using electrophoretic deposition and ultrasonic radiation

A simple wet-deposition method for preparing patterned carbon nanotube (CNT) thin films is reported. Using electrophoretic deposition (EPD), CNTs were deposited over indium tin oxide (ITO) plates that had been patterned with a photoresist; consequently, CNTs covered not only the exposed ITO areas but also the photoresist areas because thinness of the photoresists could not prevent the transverse deposition of CNTs over the photoresist areas. The ultrasonic treatment for the samples removed only CNTs on the photoresist areas, resulting in the formation of patterned CNT thin films, because Ni metal formed during EPD connects CNTs to ITO plates.     

离子液体中制备碳纳米管复合材料的研究

与传统的溶剂相比,离子液体作为一种新型的绿色环保溶剂及优良电解质,在碳纳米管复合材料制备中得到了广泛的应用.对近年来利用离子液体合成出的碳纳米管/金属复合材料、碳纳米管/纤维素复合材料、碳纳米管/聚合物复合材料,以及在高分子离子液体、离子液凝胶中制备的碳纳米管复合材料进行了综述,介绍它们的优势及特点.对今后离子液体在碳...