碳纳米管基气体传感器研究进展

碳纳米管具有灵敏度高、响应快和工作温度低等优异的气敏特性,近年来碳纳米管基气体传感器的研究成为研究热点.概述了碳纳米管基气体传感器的种类、结构特点、气敏性能和未来的发展方向,着重介绍了纯的碳纳米管包括单壁碳纳米管、多壁碳纳米管和碳纳米管阵列的气敏特性,以及碳纳米管的修饰或碳纳米管与高分子材料、氧化物等复合对其气敏性能的影响.     

Carbon Nanotube and Gold‐Based Materials: A Symbiosis

Carbon nanotubes constitute a novel class of nanomaterials with potential applications in many areas. The attachment of metal nanoparticles to carbon nanotubes is new way to obtain novel hybrid materials with interesting properties for various applications such as catalysts and gas sensors as well as electronic and magnetic devices. Their unique properties such as excellent electronic properties, a good chemical stability, and a large surface area make carbon nanotubes very useful as a support for gold nanoparticles in many potential applications, ranging from advanced catalytic systems through very sensitive electrochemical sensors and biosensors to highly efficient fuel cells. Here we give an overview on the recent progress in this area by exploring the various synthesis approaches and types of assemblies, in which nanotubes can be decorated with gold nanoparticles and explore the diverse applications of the resulting composites.     

Dispersions, novel nanomaterial sensors and nanoconjugates based on carbon nanotubes

Nanomaterials are structures with dimensions characteristically much below 100 nm. The unique physical properties (e.g., conductivity, reactivity) have placed these nanomaterials in the forefront of emerging technologies. Significant enhancement of optical, mechanical, electrical, structural, and magnetic properties are commonly found through the use of novel nanomaterials. One of the most exciting classes of nanomaterials is represented by the carbon nanotubes. Carbon nanotubes, including single-wall carbon nanotubes, multi-wall carbon nanotubes, and concentric tubes have been shown to possess superior electronic, thermal, and mechanical properties to be attractive for a wide range of potential applications They sometimes bunch to form “ropes” and show great potential for use as highly sensitive electronic (bio)sensors due to the very small diameter, directly comparable to the size of single analyte molecules and that every single carbon atom is in direct contact with the environment, allowing optimal interaction with nearby molecules. Composite materials based on integration of carbon nanotubes and some other materials to possess properties of the individual components with a synergistic effect have gained growing interest. Materials for such purposes include conducting polymers, redox mediators and metal nanoparticles. These tubes provide the necessary building blocks for electronic circuits and afford new opportunities for chip miniaturization, which can dramatically improve the scaling prospects for the semiconductor technologies and the fabrication of devices, including field-effect transistors and sensors. Carbon nanotubes are one of the ideal materials for the preparation of nanoelectronic devices and nanosensors due to the unique electrical properties, outstanding electrocatalytic properties, high chemical stability and larger specific surface area of nanotubes. Carbon nanotubes are attractive material for supercapacitors due to their unique one-dimensional mesoporous structure, high specific surface area, low resistivity and good chemical stability. Nanoscaled composite materials based on carbon nanotubes have been broadly used due to their high chemical inertness, non-swelling effect, high purity and rigidity. The integration of carbon nanotubes with organics, biomaterials and metal nanoparticles has led to the development of new hybrid materials and sensors. Hybrid nanoscale materials are well established in various processes such as organic and inorganic compounds, nucleic acid detachment, protein separation, and immobilization of enzymes. Those nanostructures can be used as the building blocks for electronics and nanodevices because uniform organic and metal coatings with the small and monodisperse domain sizes are crucial to optimize nanoparticle conductivity and to detect changes in conductivity and absorption induced by analyte adsorption on these surfaces. The highly ordered assembly of zero-dimensional and one-dimensional nanoparticles is not only necessary for making functional devices, but also presents an opportunity to develop novel collective properties.     

碳纳米管气体传感器研究进展

碳纳米管具有一维纳米结构、高表面吸附能力、良好的导电性和电子弹道传输特性等优异的力学、电学、物理和化学性能,成为制作纳米气体传感器的理想材料之一.近年来,各国研究者广泛开展了碳纳米管气体传感器的研究工作,并取得了许多显著成果.研究结果表明,碳纳米管气体传感器具有灵敏度高、响应速度快、尺寸小、能耗低和室温下工作等诸多特点.本文结合本研究小组近年来在碳纳米管气体传感器领域所做的大量研究工作,从环境监测、医学检测和国防军事等方面,对碳纳米管气体传感器取得的研究进展进行了综述,同时也阐述和分析了碳纳米管气体传感器的工作原理和制作过程.尽管面临诸多挑战,随着研究的不断深入,碳纳米管气体传感器仍有可能凭借其独特的性能优势成为当前商业应用气体传感器的有力竞争者.     

Functionalization and Dissolution of Single-Walled Carbon Nanotubes by Chemical-Physical and Electrochemical Treatments

Single-Walled Carbon Nanotubes (SWCNTs) possess a wealth of exceptional structural, mechanical and electronic properties. These have made them potentially useful for applications in nanotube-reinforced materials, nanoelectronic devices, field emitters, probe tips for SPM, as well as for sensors, biosensors, and actuators. However, manipulation and processing of SWCNTs has been limited by their insolubility in most common solvents, although some dissolution has recently been obtained. Their chemical modification might pave the way to many useful applications, including the preparation of composite materials or the immobilization of biological molecules as enzymes (i.e., for biosensors and electrochemical sensors). Attachment of oxygen-containing functional groups (i.e., carboxy groups, carbonyl groups, hydroxy groups, etc.) on the surface of the carbon nanotubes could be achieved using different pretreatments of the nanostructured material. These involved (a) chemical and physical procedures; and (b) electrochemical functionalization. Different attempts at sidewall modification have been hampered by the presence of significant contaminants as graphitic and amorphous carbon or have required solubilization via chemical reactions on the ends of cut nanotubes. A more accommodating and direct approach to functionalize nanotubes is therefore required. We report here the sidewall functionalization of purified SWCNTs, obtained by different approaches and finally, we can discuss possible applications of functionalized SWCNTs in the sensing area.     

Electrochemical Sensors Based on Carbon Nanotubes

Carbon nanotubes are attractive new materials. It has been about a decade since carbon nanotubes were discovered. Carbon nanotubes have many outstanding properties and have many practical or potential applications. In this short review we introduce recent advances in carbon nanotubes as potential material for electrochemical sensors. The advantages of carbon nanotubes as sensors are discussed along with future prospects.     

Carbon nanotubes and graphene in analytical sciences

Nanosized carbon materials are offering great opportunities in various areas of nanotechnology. Carbon nanotubes and graphene, due to their unique mechanical, electronic, chemical, optical and electrochemical properties, represent the most interesting building blocks in various applications where analytical chemistry is of special importance. The possibility of conjugating carbon nanomaterials with biomolecules has received particular attention with respect to the design of chemical sensors and biosensors. This review describes the trends in this field as reported in the last 6?years in (bio)analytical chemistry in general, and in biosensing in particular.

碳纳米管用作超级电容器电极材料

碳纳米管由于具有化学稳定性好、比表面积大、导电性好和密度小等优点,是很有前景的超级电容器电极材料。本文介绍了碳纳米管用作超级电容器电极材料的研究现状,总结了单纯碳纳米管电极材料和碳纳米管复合物电极材料的特点与性能,并探讨了今后碳纳米管电极材料的发展方向。     

A Review on the Effects of Introducing CNTs in the Modification Process of Electrochemical Sensors

This review summarizes some developments in the fabrication of modified sensors and biosensors through the incorporating the carbon nanotubes (CNTs) in their modification ingredients. A large number of papers have paid attention towards the application of carbon nanotubes (CNTs) as electrode constituents and studied its electrochemical behavior. Here, we survey the achievements in the detection of various substances with high selectivity and sensitivity provided using CNTs based electrodes. Moreover, modified electrodes by CNTs have demonstrated the electrocatalytic features and higher sensitivity in detection of analytes. The improved characteristics arises from the large surface area and good conductivity of CNTs. However, it should be considered that the use of single walled carbon nanotubes (SWCNTs) or multi‐walled carbon nanotubes (MWCNTs), the presence of impurities, and the chemical procedures adopted are effective on the performance of the modified sensors.     

Mechanical properties of carbon nanomaterials.

Carbon nanomaterials show a variety of interesting chemical and physical properties. In this Minireview we focus on the mechanical properties of carbon nanomaterials with emphasis on carbon nanotubes and their composite materials. We introduce some recently developed components made of carbon nanotube composite materials and outline their importance for applications in everyday life.     

二氧化钛纳米管的研究进展

二氧化钛纳米管由于其新奇的光电、催化、气敏等性能引起了广泛的关注,在太阳能电池、光催化、环境净化、气体传感器等领域有潜在的应用价值.本文概述了近年来在制备方法、反应机理和组成、晶型和形貌及掺杂和应用方面的进展,并讨论了今后可能的研究发展方向.     

Proton-fueled DNA-duplex-based stimuli-responsive reversible assembly of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs) have received much attention in nanotechnology because of their potential applications in molecular electronics, field-emission devices, biomedical engineering, and biosensors. Carbon nanotubes as gene and drug delivery vectors or as "building blocks" in nano-/microelectronic devices has been successfully explored. However, since SWNTs lack chemical recognition, SWNT-based electronic devices and sensors are strictly related to the development of a bottom-up self-assembly technique. Here we present an example of using DNA duplex-based protons (H(+)) as a fuel to control reversible assembly of SWNTs without generation of waste duplex products that poison DNA-based systems.     

Single carbon nanotube optical spectroscopy.

This Minireview discusses novel insights into the electronic structure of carbon nanotubes obtained using single-molecule fluorescence spectroscopy. Fluorescence spectra from single nanotubes are well described by a single, Lorentzian lineshape. Nanotubes with identical structures fluoresce with different energies due to local electronic perturbations. Carbon nanotube fluorescence unexpectedly does not-show any intensity or spectral fluctuations at 300 K The lack of intensity blinking or bleaching demonstrates that carbon nanotubes have the potential to provide a stable, single-molecule infrared photon source, allowing for the exciting possibility of applications in quantum optics and biophotonics.     

Carbon nanofiber vs. carbon microparticles as modifiers of glassy carbon and gold electrodes applied in electrochemical sensing of NADH

Carbon materials (CMs), such as carbon nanotubes (CNTs), carbon nanofibers (CNFs), and carbon microparticles (CMPs) are used as doping materials for electrochemical sensors. The efficiency of these materials (either before or after acidic treatments) while being used as electrocatalysts in electrochemical sensors is discussed for β-nicotinamide adenine dinucleotide (NADH) detection using cyclic voltammetry (CV). The sensitivity of the electrodes (glassy carbon (GC) and gold (Au)) modified with both treated and untreated materials have been deeply studied. The response efficiencies of the GC and Au electrodes modified with CNF and CMP, using dimethylformamide (DMF) as dispersing agent are significantly different due to the peculiar physical and chemical characteristics of each doping material. Several differences between the electrocatalytic activities of CMs modified electrodes upon NADH oxidation have been observed. The CNF film promotes better the electron transfer of NADH minimizing the oxidation potential at +0.352 V. Moreover higher currents for the NADH oxidation peak have been observed for these electrodes. The shown differences in the electrochemical reactivities of CNF and CMP modified electrodes should be with interest for future applications in biosensors.     

Soluble carbon nanotubes

Carbon nanotubes have attracted great interdisciplinary interest because of their unique structure and properties. However, carbon-nanotube research is challenged by several problems, such as: i) mass production of material, ii) control of length, diameter, and chirality, and iii) manipulation for use in diverse technological fields. Issues regarding the synthesis and purification as well as the functionalization and solubilization of carbon nanotubes are relevant topics in this rapidly growing field. In this paper, covalent and noncovalent approaches to functionalized and solubilized nanotubes are examined in detail, with particular emphasis on the change of properties that accompany the chemical modification.     

Carbon nanotubes as solid-phase extraction sorbents prior to atomic spectrometric determination of metal species: A review

New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high adsorption and desorption capacities – have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed.     

Aligned Nanotubes

Since the discovery of carbon nanotubes by Iijima in 1991, various carbon nanotubes with either a single‐ or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size‐dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat‐panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.     

Chemical and biochemical sensing with modified single walled carbon nanotubes

The nano dimensions, graphitic surface chemistry and electronic properties of single walled carbon nanotubes make such a material an ideal candidate for chemical or biochemical sensing. Carbon nanotubes can be nondestructively oxidized along their sidewalls or ends and subsequently covalently functionalized with colloidal particles or polyamine dendrimers via carboxylate chemistry. Proteins adsorb individually, strongly and noncovalently along nanotube lengths. These nanotube-protein conjugates are readily characterized at the molecular level by atomic force microscopy. Several metalloproteins and enzymes have been bound on both the sidewalls and termini of single walled carbon nanotubes. Though coupling can be controlled, to a degree, through variation of tube oxidative pre-activation chemistry, careful control experiments and observations made by atomic force microscopy suggest that immobilization is strong, physical and does not require covalent bonding. Importantly, in terms of possible device applications, protein attachment appears to occur with retention of native biological structure. Nanotube electrodes exhibit useful voltammetric properties with direct electrical communication possible between a redox-active biomolecule and the delocalized pi system of its carbon nanotube support.     

Chemical functionalization of single-walled carbon nanotube field-effect transistors as switches and sensors

Because of the one-dimensional (1D) nanostructural nature of single-walled carbon nanotubes (SWNTs) and their advantages of chemical flexibility and sensitivity arising from the susceptibility of their active surfaces to interacting species, great effort has been made to integrate carbon nanotube field-effect transistors (NTFETs) into functional optoelectronic devices capable of converting external stimuli to easily detectable electrical signals. In this Review article, we aim to capture recent advances of rational design and chemical functionalization of NTFETs for the purpose of switching or biosensing applications. To provide a deeper understanding of the device responses to analytes, this review will also survey the proposed sensing mechanisms. As demonstrated by these remarkable examples, the concept of combining the proper selection of functional molecular materials and molecular self-assembly with device micro/nanofabrication offers attractive new prospects for constructing NTFET-based molecular optoelectronic devices with desired functionalities.