碳纳米管的改性与应用

本文主要介绍对碳纳米管不同位置的修饰以及其应用等方面的研究进展,并对今后的研究方向进行展望.     

超声喷雾化学镀法制备镀Ni碳纳米管及其微波吸收性能

将碳纳米管（CNTs）经过酸化、敏化和活化处理后,采用超声喷雾化学镀的方法来制备镀Ni碳纳米管（Ni-CNTs）。采用TEM、EDS和拉曼光谱进行表征。结果表明,采用超声喷雾化学镀可实现Ni层在CNTs表面均匀连续的镀覆,并且改善了CNTs的分散性,有利于其在复合材料领域的应用。不同形貌的Ni-CNTs的吸波性能有明显差异。对于镀层相对较薄的Ni-CNTs试样,其反射损耗峰值为-17.12 dB,出现在9.36 GHz处;吸波频带宽度为5.28 GHz（R<-5 dB）和2 GHz（R<-10 dB）,这样的趋势有利于制造宽频复合吸波材料。     

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,...     

Ni催化剂在N2O／N2／NH3中退火对碳纳米管表面结构及场发射特性的影响

研究在N2O/N2/NH3氛围中对Ni催化剂进行退火处理,旨在探讨退火处理对所生成碳纳米管的表面结构及其发射特性的影响.从表面结构及表面元素分析结果发现:Ni催化剂在N2O/N2/NH3氛围中退火处理之后,Ni催化剂的颗粒大小及催化剂的化学成分发生改变,进而影响所合成的碳纳米管的表面结构及场发射特性.扫描电镜显示:经过N2O退火前处理后,催化金属薄膜在成核时较易形成均匀性的金属颗粒,且金属颗粒较小.比较经N2O/N2/NH3氛围退火处理之后所合成的碳纳米管结果,经过N2O前处理可以有效抑制非品质碳的成长,使所成长出的碳纳米管数量最多、场发射电流最大.原因主要是因为N2O对催化剂镍膜金属前处理过程中分解出的氮原子及氧原子会活化及氧化催化剂Ni金属,并使所形成的Ni金属颗粒较小且更为均匀,造成表面型态上的显著改变,有助于使合成的碳纳米管场发射电流变大.     

碳纳米管/平面各向异性羰基铁复合材料的液相共混法制备及其电磁性能

采用机械球磨法制备了平面各向异性羰基铁（Planar Anisotropic Carbonyl Iron,PACI）,然后通过液相共混法制备了碳纳米管（CNTs）/PACI复合材料。采用同轴法测定CNTs/PACI复合材料在2~18 GHz频段内的复介电常数和复磁导率,研究了CNTs掺杂量对复合材料电磁性能的影响。结果表明：CNTs/PACI复合材料相对于PACI具有更高的复介电常数和衰减常数,随着CNTs质量分数的提高,复合材料的复介电常数和衰减常数逐渐增大,特征阻抗则逐渐减小。CNTs掺杂能够有效提高CNTs/PACI复合材料的吸波性能,通过调整厚度和CNTs掺杂量可以对复合材料的吸波性能进行有效调控。厚度为1.2 mm、CNTs质量分数为2wt%和厚度为1.6 mm、CNTs质量分数为0.5wt%的CNTs/PACI复合材料在Ku波段（12~18 GHz）的反射率均小于-10 dB;厚度为2.0 mm、CNTs质量分数为0.5wt%和1wt%的复合材料反射率小于-10 dB的频带宽分别为5.28 GHz（8.24~13.52 GHz）和5.04 GHz（7.52~12.56 GHz）,覆盖整个X波段（8~12 GHz）。     

Structural mechanics of carbon nanotubes: From continuum elasticity to atomistic fracture

Summary Motivated by recent observations of bent, collapsed and twisted carbon nanotubes, we investigate their behavior at large deformations. These hollow molecules behave remarkably similar to their macroscopic homologs. They reversibly switch into different morphological patterns, and each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. These transformations, simulated using a realistic many-body potential, are accurately described by a continuum-shell model. In contrast, a response to axial tension proceeds smoothly up to a fracture threshold, beyond which a monoatomic carbon chain unravels between the tube fragments.     

Nanowires sheathed inside nanotubes: Manipulation,properties and applications

Since the discovery of metals encapsulated into multi-walled carbon nanotubes (CNTs), such sheathed structures attracted extensive interest with respect to the development of various synthetic strategies for producing the unique structure of nanowires sheathed inside nanotubes. The nanowire materials varied from metals to alloys, from semiconductors to insulators, and even metal–semiconductor heterojunctions were tried. In recent years, the studies on these nanostructures have been mainly focused on in-situ manipulation, property analysis and applications. Exploration of on-demand nano-engineering of the regarded structures toward practical device design and fabrication was mainly guided by high-resolution transmission electron microscopy (TEM) technique combining new capabilities of implementation of atomic force (AFM) or scanning tunneling microscopy (STM) holders, and heating/cooling holders. Such novel in-situ TEM techniques have rapidly developed to a stage where they truly become a very powerful tool for the studies of core/shell nanowire heterostructures. In this review, we summarize the significant developments and achievements in regards of manipulation, property measurements and device applications of inorganic nanowires sheathed inside nanotubes according to different categories of the filling materials, i.e., metals, alloys, compounds and semiconductor–metal heterojunction nanowires. We also highlight the irreplaceable value of in-situ TEM technology in this field, compare different fillings for so-called nanothermometers, discuss mass transportation mechanism in nanotubes, and conclude with an outlook of future developments and challenging issues that are still in the premature stage.     

Amorphous oxide semiconductors: From fundamental properties to practical applications

Amorphous oxide semiconductors (AOSs) have exceptional features of high visible transparency, high carrier mobility, excellent uniformity, and low-temperature growth process, making them promising in the electronic and information industry. InGaZnO is the most widely studied AOS and has been applied in commercial, which, however, contains rare and precious indium. For sustainable development, a diversity of In-free AOSs have been designed and proposed, which are attracted more and more attention. There have been several reviews on AOSs mainly centred on InGaZnO; in contrast, the review on In-free AOSs is not available at present. In this work, we provide a comprehensive review on In-free AOSs from fundamental properties to practical applications. Various In-free AOSs available in literatures are introduced, with the focus on ZnSnO-based AOSs. Thin-film transistors (TFTs) based on In-free AOSs are investigated in detail, which are the key device for next-generation transparent and flexible displays. Also, the applications in transparent electrodes, sensors, memristors, synaptic devices, and circuits are introduced. This review is expected to provide a guide to well understand the state-of-the-art principles, materials, devices, fabrication, applications, and perspectives of In-free AOSs.     

Nanocomposites based on conducting polymers and carbon nanotubes: from fancy materials to functional applications

This review deals with recent progress on the development of nanocomposite materials formed by conducting organic polymers (COPs) and carbon nanotubes (CNs), both from a fundamental and applied point of view. The combination of the unique properties of CNs with COPs makes of these materials interesting multifunctional systems with great potential in many applications such as supercapacitors, sensors, photovoltaic cells and photodiodes, optical limiting devices, solar cells, high-resolution printable conductor, electromagnetic absorbers, and, last but not least, advanced transistors.     

Inorganic lead-based halide perovskites: From fundamental properties to photovoltaic applications

Compared with organic–inorganic hybrid halide perovskites (OIHPs), inorganic cesium lead halide perovskites (CsPbX₃) possess superior intrinsic stability for high temperatures and are considered one of the most attractive research hotspots in the perovskite photovoltaic (PV) field in the past several years. The PCE of CsPbX₃ inorganic perovskite solar cells (IPSCs) has increased from 2.9% in 2015 to more than 20% with excellent stability. There are still many on-going studies on the properties of perovskite materials and their applications in PV technology, thereby needing a thorough understanding. Here, the progress of inorganic perovskites is systematically introduced, including the fundamental properties of CsPbX₃ materials and CsPbX₃-based PV devices. The origins of stability and instability of CsPbX₃ and defects in CsPbX₃ are discussed. CsPbI₃-, CsPbI₂Br-, CsPbIBr₂- and CsPbBr₃-based PV devices and performance are comprehensively reviewed. The stabilization methods and mechanism for the photoactive phases of inorganic perovskites with low bandgap are emphasized. Reported strategies to boost the performance of CsPbX₃-based IPSCs are summarized. In the end, the potential of inorganic perovskites is evaluated, which opens up new prospects for the commercialization of IPSCs.     

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.     

Preparation and investigation on properties of lysozyme chemically bonded to single-walled carbon nanotubes

The purpose of this research is the preparation of a lysozyme-single-walled carbon nanotube (SWCNT) conjugate and investigation of the effect of conjugation on the structure and function of lysozyme. At first, SWCNTs were functionalised by oxygen and lysozyme was coupled to the SWCNTs by carbodiimide method. The high chemical stability of conjugation was purposed for the SWCNTs conjugated enzyme as approved by Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM) images, agarose gel electrophoresis and X-ray diffraction (XRD) patterns. The degree of conjugation was determined by thermogravimetric analysis (TGA) process. The results showed no significant differences between the XRD patterns of the native lysozyme and conjugated lysozyme–SWCNTs and these indicated excellent capacity of the SWCNTs to conjugated enzyme. The gel electrophoresis studies and TEM image confirmed the covalent attachment of the enzyme to the functionalised SWCNTs. These results revealed that the enzyme retain a high fraction of their native structure and activity upon attachment to SWCNTs. Therefore, this conjugated protein represents novel preparations that make it an attractive choice as a natural antimicrobial agent.     

Nano-silver modified carbon nanotubes to reinforce the copper matrix composites and their mechanical properties

In ensuring the effective load transfer of carbon nanotubes (CNTs) reinforced copper (Cu)-based composites, good and stable interface contact is a key factor. Powder electrodeposition technology is used in the present study to coat silver (Ag) nanoparticles on CNTs for the first time. Subsequently, by ball milling and spark plasma sintering, uniform distribution of CNTs in the Cu matrix and tight Cu/C interface bonding are successfully achieved. It is found that Ag nanoparticles with a size of 5 nm are evenly embedded in the surface of CNTs. The results reveal that the agglomeration of CNTs is prevented by the addition of Ag nanoparticles and the adhesion between CNTs and Cu matrix is enhanced by the formation of coherent interface. Further, the load transfer of composite materials is effectively realized by the pinning effect of Ag particles on CNTs. The tensile strength, elongation, and conductivity of the 0.75 CNT-Ag/Cu samples were 314 MPa, 24.8%, and 93.6% IACS, respectively, which are 40.1%, 818%, and 3.3% higher than those of the CNT/Cu samples, respectively. The present method provides a new direction for the uniform coating powder materials and the synergistic strengthening of metal matrix composites.     

TiO2 nanotubes: Self-organized electrochemical formation, properties and applications

The present paper gives an overview and review on self-organized TiO₂ nanotube layers and other transition metal oxide tubular structures grown by controlled anodic oxidation of a metal substrate. We describe mechanistic aspects of the tube growth and discuss the electrochemical conditions that need to be fulfilled in order to synthesize these layers. Key properties of these highly ordered, high aspect ratio tubular layers are discussed. In the past few years, a wide range of functional applications of the layers have been explored ranging from photocatalysis, solar energy conversion, electrochromic effects over using the material as a template or catalyst support to applications in the biomedical field. A comprehensive view on state of the art is provided.     

Recent progress in the development and properties of novel metal matrix nanocomposites reinforced with carbon nanotubes and graphene nanosheets

One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.     

Macroscopic carbon nanotube assemblies: preparation, properties, and potential applications

As classical 1D nanoscale structures, carbon nanotubes (CNTs) possess remarkable mechanical, electrical, thermal, and optical properties. In the past several years, considerable attention has been paid to the use of CNTs as building blocks for novel high-performance materials. In this way, the production of macroscopic architectures based on assembled CNTs with controlled orientation and configurations is an important step towards their application. So far, various forms of macroscale CNT assemblies have been produced, such as 1D CNT fibers, 2D CNT films/sheets, and 3D aligned CNT arrays or foams. These macroarchitectures, depending on the manner in which they are assembled, display a variety of fascinating features that cannot be achieved using conventional materials. This review provides an overview of various macroscopic CNT assemblies, with a focus on their preparation and mechanical properties as well as their potential applications in practical fields.     

Influence of carbon nanotubes and dispersions of SiC on the physical and mechanical properties of pure copper and copper‐nickel alloy

This paper investigates the physical and mechanical properties of copper‐nickel alloy (at 50 wt.%–50 wt.%) and pure copper, mixed with various types of reinforcement materials such as carbon nanotubes (0.5 wt.%–2 wt.%) as nanoparticles, silicon carbide (1 wt.%–4 wt.%) as microparticles. The acquired composite specimens characteristics were estimated such as microstructure, density, electrical and thermal conductivity, hardness, and compression stress properties to determine the suitable reinforcement percentage that has the best physical and mechanical properties with different main matrix material whether copper‐nickel mechanical alloying or pure copper powder. The micron‐sized silicon carbide and nanosized carbon nanotubes were added to improve the mechanical and physical properties of the composite. The electrical and thermal conductivity of pure copper alloy enhanced compared with the copper‐nickel alloy matrix material. The hardness and compression yield stress of both pure copper and copper‐nickel composites have enhancement values and for copper‐nickel base composites hardness and compression yield stress have enhanced with the most positive enhancement values to examined an optimum percentage of reinforcing material.     

Physical properties of carbon nanotubes radiated by proton beams: Gas adsorption and electron microscopy studies

Single walled carbon nanotues (SWCNTs) of high purity and multi walled carbon nanotubes (MWCNTs) were radiated by high energies of proton and electron beams. The surface physical properties were examined by XRD and TEM for both irradiated and non-radiated samples to compare the effect of radiation. The possible changes of surface characteristics were investigated by isotherm gas adsorption technique using Ar which can probe the local structure in an order of atomic scale. A series of Ar gas adsorption results measured below 77 K revealed significant changes in surface properties of carbon nanotubes by the bombardment of proton beams, which may induce the local surface defects. It is speculated that reactions on carbon nanotubes radiated by beams were led by kinetic energy transfer of the bombardments.     

From micro to nano: properties and potential applications of micro- and nano-filled polymer ceramic composites in microsystem technology

In microsystem technology, four important material classes are established either for the generation or the replication of microstructured surfaces: silicon, polymers, metals and ceramics. Composite materials consisting of a polymer matrix and ceramic fillers show improved thermomechanical properties in comparison to polymers and can be introduced as a new additional material class. The substitution of micro-sized ceramic fillers by nano-sized ceramics in composites has a strong influence on the composite's physical properties: the reduction of ceramic particle size down to the nanometre scale results in an improved sinter activity owing to the large surface area. The fabrication of dense ceramics is simplified and can be used for a rapid prototyping of microstructured ceramic parts. The addition of nano-sized ceramics with particle sizes of <40 nm to polymers allows the manufacturing of transparent polymer based composites with modified refractive indices for use in polymer waveguides. The influence of the ceramic particle size, the ceramic content and different dispersion methods on the composite's physical properties are discussed.     

Fabrication of PbS nanoparticle coated amorphous carbon nanotubes: Structural, thermal and field emission properties

A simple chemical route for the synthesis of PbS nanoparticle coated amorphous carbon nanotubes (aCNTs) was described. The nanocomposite was prepared from an aqueous suspension of acid functionalized aCNTs, lead acetate (PbAc), and thiourea (TU) at room temperature. The phase formation and composition of the samples were characterized by X-ray diffraction and energy dispersive analysis of X-ray studies. The Fourier transformed infrared spectra analysis revealed the attachment of PbS nanoparticles on the acid functionalized aCNT surfaces. Morphology of the samples was analyzed with a field emission scanning electron microscope. UV-Vis study also confirmed the attachment of PbS nanoparticles on the walls of aCNTs. Thermal gravimetric analysis showed that the PbS coated aCNTs are more thermally stable than functionalized aCNTs. The PbS coated aCNTs showed enhanced field emission properties with a turn-on field 3.34 V μm⁻¹ and the result is comparable to that of pure crystalline CNTs.