Multifunctional MXene/Carbon Nanotube Janus Film for Electromagnetic Shielding and Infrared Shielding/Detection in Harsh Environments

Multifunctional,flexible,and robust thin films capable of operating in demanding harsh temperature environments are crucial for various cutting-edge applications.This study presents a multifunctional Janus film integrating highly-crystalline Ti_(3)C_(2)T_(x) MXene and mechanically-robust carbon nanotube(CNT)film through strong hydrogen bonding.The hybrid film not only exhibits high electrical conductivity(4250 S cm^(-1)),but also demonstrates robust mechanical strength and durability in both extremely low and high temperature environments,showing exceptional resistance to thermal shock.This hybrid Janus film of 15μm thickness reveals remarkable multifunctionality,including efficient electromagnetic shielding effectiveness of 72 dB in X band frequency range,excellent infrared(IR)shielding capability with an average emissivity of 0.09(a minimal value of 0.02),superior thermal camouflage performance over a wide temperature range(−1 to 300℃)achieving a notable reduction in the radiated temperature by 243℃ against a background temperature of 300℃,and outstanding IR detection capability characterized by a 44%increase in resistance when exposed to 250 W IR radiation.This multifunctional MXene/CNT Janus film offers a feasible solution for electromagnetic shielding and IR shielding/detection under challenging conditions.

Field Emission from a Mixture of Amorphous Carbon and Carbon Nanotubes Films

A mixture of amorphous carbon and carbon nanotubes films was synthesized on stainless steel plates by a micro- wave plasma enhanced chemical vapor deposition system. The source gases were hydrogen and methane with flow rates of 100 and 16sccm,respectively,with a total pressure of 5.0kPa. The surface morphology and the structure of the films were characterized by field emission scanning electron microscopy （SEM） and Raman scattering spectroscopy. Field emission properties of as-deposited film were measured in a vacuum room below 5 ×10^ 5 Pa. The experimental results show that the initial turn-on field is 0. 9V/μm; The current density is 4.0mA/cm2 and the emission sites are dense and uniform at an electric field of 3.7V/μm. These results indicate that such a mixture of amorphous carbon and carbon nanotubes films is a promising material for field emission applications.

Temperature Dependent Surface Resistivity Measures of Commercial, Multiwall Carbon Nanotubes (MWCNT), and Silver Nano-Particle Doped Polyvinyl Alcohol (PVA) Films

Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.

Carbon nanotube and graphene reinforced magnesium matrix composites:A state-of-the-art review

Magnesium(Mg)composites reinforced with carbon-based nanomaterial(CBN)often exhibit low density,enhanced strength,good conductivity,improved wear resistance,and excellent biocompatibility when compared to current industry Mg alloys.This review aims to critically evaluate recent developments in Mg-CBN composites and is divided into five sections:First,a brief introduction to Mg-CBN composites is provided,followed by a discussion of different fabrication techniques for these composites,including powder metallurgy,casting,friction stir processing,and selective laser melting.A particular focus is on the current processing challenges,including dispersion strategies to create homogeneous Mg-CBN composites.The effect of processing on the quantifying disorder in CBNs and distinguishing different sp2carbon materials is also highlighted.Then,the effect of CBN on various properties of Mg-CBN composites is thoroughly analyzed,and the strengthening efficiency of CNTs and graphene in the Mg matrix is examined.Finally,the potential applications of Mg-CBN composites in various industries are proposed,followed by a summary and suggestions for future research directions in the field of Mg-CBN composites.

Printable Aligned Single-Walled Carbon Nanotube Film with Outstanding Thermal Conductivity and Electromagnetic Interference Shielding Performance

Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.

A flexible carbon nanotube@V_(2)O_(5) film as a high-capacity and durable cathode for zinc ion batteries

Aqueous zinc-ion batteries(ZIBs)are receiving a continuously increasing attention for mobile devices,especially for the flexible and wearable electronics,due to their non-toxicity,non-flammability,and low-cost features.Despite the significant progress in achieving higher capacities for electrode materials of ZIBs,to endow them with high flexibility and economic feasibility is,however,still a significant challenge remaining unsolved.Herein,we present a highly flexible composite film composed of carbon nanotube film and V_(2)O_(5)(CNTF@V_(2)O_(5))with high strength and high conductivity,which is prepared by simply impregnating a porous CNT film with an aqueous V_(2)O_(5)sol under vacuum.For this material,intimate incorporation between V_(2)O_(5)and CNTs has been achieved,successfully integrating the high zinc ion storage capability with high mechanical flexibility.As a result,this CNTF@V_(2)O_(5)film delivers a high capacity of 356.6 m Ah g^(-1)at 0.4 A g^(-1)and excellent cycling stability with 80.1%capacity retention after 500 cycles at 2.0 A g^(-1).The novel strategy and the outstanding battery performance presented in this work should shed light on the development of high-performance and flexible ZIBs.

Simple method to rapidly fabricate chain-like carbon nanotube films and its field emission properties

A simple process to fabricate chain-like carbon nanotube （CNT） films by microwave plasma-enhanced chemical vapor deposition （MPCVD） was developed successfully. Prior to deposition, the Ti/Al2O3 substrates were ground with Fe-doped SiO2 powder. The nano-structure of the deposited films was analyzed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Raman spectroscopy. The field electron emission characteristics of the chain-like carbon nanotube films were measured under the vacuum of 10-5 Pa. The low turn-on field of 0.80 V/μm and the emission current density of 8.5 mA/cm2 at the electric field of 3.0 V/μm are obtained. Based on the above results, chain-like carbon nanotube films probably have important applications in cold cathode materials and electrode materials.

Dispersion and Performance Properties of Carbon Nanotubes (CNTs) Based Polymer Composites: A Review

Carbon nanotubes (CNTs) based polymer composites have variety of engineering applications (electromagnetic shielding, antistatic coatings, high-strength low-density corrosion-resistant components, lightweight energy storage and many more);due to their excellent mechanical, electrical, chemical, magnetic, etc. properties. In the polymer nanocomposites CNTs are dispersed in the polymeric matrix. However the dispersion may be uniform or may not be uniform. The biggest challenge is the effective dispersion of individual CNTs in the polymer matrices, as CNTs tends to form clusters and bundles due to strong van der Waals’ forces of attraction. The aggregated structure continue until physical (Mechanical) or chemical modification (Encapsulation/surface modification) of CNTs. Few modification methods such as vigorous mixing of the polymers damages CNTs structure, and may hinder their properties. But these problems can be overcome by mechanical or chemical modification of CNTs surfaces. In the chemical modification, the modifier or the long tail surfactant may encapsulate and/or partially wrap the CNTs surfaces. In this review, recent work on CNTs based polymer nanocomposite is carried out with few modifiers/encapsulating agents. Incorporation of CNTs in polymer matrix changes the performance properties such as tensile strength, tensile modulus, elongation at break, toughness, Dynamic mechanical thermal analysis (DMTA), etc. The phase morphology of the composite materials throws light on the properties of CNTs based polymer nanocomposite. Moreover phase morphology may be directly correlated with the behavior of the material, hence reviewed here through transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Furthermore review is also carried out on the non-isothermal crystallization (DSC) and rheology of CNTs polymer nanocomposite.

Assembly and Applications of Carbon Nanotube Thin Films

The ultimate goal of current research on carbon nanotubes （CNTs） is to make breakthroughs that advance nanotechnological applications of bulk CNT materials. Especially, there has been growing interest in CNT thin films because of their unique and usually enhanced properties and tremendous potential as components for use in nano-electronic and nano-mechanical device applications or as structural elements in various devices. If a synthetic or a post processing method can produce high yield of nanotube thin films, these structures will provide tremendous potential for fundamental research on these devices. This review will address the synthesis, the post processing and the device applications of self-assembled nanotube thin films.

A general surface-treatment-free approach to fabrication of alignment layers using a super-aligned carbon nanotube film template

We develop a general approach to the fabrication of films with unidirectional grooves, such as silicon nitride, silicon dioxide and aluminium oxide, in which the surface is not required to be treated. Super-aligned carbon nanotube （SACNT） film may be used as a template and as sacrificial layer, which is subsequently removed by heating in an atmosphere of air. The unidirectional morphology of the SACNT film turns into a desired film, which is found to possess the ability to align liquid crystal molecules. This approach also features high efficiency, low cost and easy scaling-up for mass production.

Carbon nanotube film synthesized from ethanol and its oxidation behavior in air

In this paper, we propose an efficient way to synthesize carbon nanotube films using ferrocene and ethanol. The as-grown film is free-standing, semi-transparent, and of macro scale size. The tubes in the film are mostly single- or double-walled. The oxidation behavior of the film is studied via Raman spectroscopy, and the result indicates that the inner wall of the double-walled tube is effectively protected from oxidation by the outer wall.

Platinum Wire Implants Coated with PEDOT/Carbon Nanotube Conducting Polymer Films in the Brain of Rats: A Histological Evaluation

Platinum （Pt） implants coated with poly （3, 4-ethylenedioxythiophene）/carbon nanotube （PEDOT/CNT） composite films were implanted into the brain of rats, and the brain response was evaluated 6 weeks after the implantation. The surface morphology of Pt implants with and without the PEDOT/CNT coating was studied using scanning electron microscopy （SEM）. After 6 weeks post-implantation, the expression of laminin （vascular endothelial marker） and neuronal nuclei （NeuN, neuronal marker） were evaluated by immnohistochemistry. It is revealed that the obvious improvements of the surface density of blood vessels and neurons aound the Pt implants with the coating, which were evidenced by laminin and NeuN staining in the zone within the distance of 150 μm to the implant interface. These results suggest the PEDOT/CNT composite films can improve the biocompatibility of the Pt electrodes while it is implanted in brain.

Tensile and Electro-Mechanical Properties of Carbon Nanotube Film Twisted Yarn with Adjustable Diameter

Carbon nanotube(CNT)yarns with adjustable diameters were manufactured by twisting CNT films with varied twists.Different from traditional CNT fibers,CNT yarns exhibited a larger diameter(423μm)and a higher tensile force(1988 cN).The results showed that CNT yarns with the twist angle of 35°exhibited the highest conductivity(886 S/cm)and the highest tensile strain(35%).

Observation of 550 MHz passively harmonic mode-locked pulses at L-band in an Er-doped fiber laser using carbon nanotubes film

We demonstrate a passively harmonic mode-locked（PHML） fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol（CNTs-PVA） film. Under suitable pump power and an appropriate setting of the polarization controller（PC）, the 54^（th） harmonic pulses at the L-band are generated with the side mode suppression ratio（SMSR） better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.

Effects of Orientation of Carbon Nanotubes on CNT Bundle Based Silk Composite Using Finite Element Method

Carbon Nanotubes (CNTs) have exceptional mechanical properties. They are the stiffest and strongest material, yet discovered, because of their high length to diameter ratio. In this paper a Representative Volume Element (RVE) model of CNT-silk composite is made. Then the orientations of the CNTs in the composite are varied and the effects of this variation are observed. The change is mainly observed between the interfaces of CNT and silk. Also there is a change in Young’s Modulus. COMSOL Multiphysics 4.2a is used for building model and performing simulations.

A High-Luminescence Fringelike Field Emission from Screen-Printed Carbon Nanotube and Zinc Oxide Composite Film

A fringelike field emission with high-luminescence and stable emission current from screen-printed carbon nanotube mixed zinc oxide (CNT-ZnO) composite cathode was investigated. The luminescent patterns are significantly different from those observed in the field emission measure of pure CNT cathode. SEM images reveal that the CNTs are perfectly matched with ZnO powders by filling the interspaces in CNT film. XRD analysis demonstrates that the CNTs and ZnO have a high degree of crystalline perfection. Field emission measurement exhibits that the turn-on field of CNT-ZnO cathode is 2.08 V/μm, lower than 2.46 V/μm for pure CNT cathode. The large fringelike emission current at the brims of CNT-ZnO cathode is attributed to a combination of the increased effective contact area of CNTs, which decrease the sheet resistance of cathode film, and the dangled CNT bundles at the brims of CNT-ZnO film cathode.

Study on Low-Temperature Properties of the Asphalt Modified by Carbon Nanotubes(CNTs)and Crumb Rubber(CR)

The effect of adding crumb rubber(CR)and carbon nanotubes(CNTs)on the low-temperature properties of virgin asphalt was studied.Using the force-ductility test and the bending beam rheometer(BBR)test,the deformation resistance and rheological properties of asphalt samples at low temperatures were evaluated,respectively.Based on the result of BBR test,the creep functions of the Burgers model and the Zener model were used to fit the low-temperature creep characteristics of the asphalt samples.Furthermore,the differential scanning calorimetry(DSC)test and the attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR)test were utilized to appraise the low-temperature stability and chemical properties of asphalt samples,respectively.The results showed that CR significantly improved the low-temperature properties of virgin asphalt,while CNTs had little effect.Moreover,during the degradation of CR,aromatic and aliphatic components were released.In particular,the aliphatic components of CR-modified asphalt were much higher than those of virgin asphalt,which had a significant effect on improving the low-temperature properties of the asphalt.The DSC test results showed that CR enhanced the low-temperature stability of the asphalt,while the addition of CNTs presented a slightly negative effect.

Optical-Electronic Properties of Carbon-Nanotubes Based Transparent Conducting Films

Three coating methods (slot, dip and blade coatings) were used separately to coat a well-dispersed single-wall carbonnanotube (SWCNT) solution on polyethylene terephthalate (PET) film, and the resulting optical and electronic properties were measured and compared. It was found that the sheet resistance and the transparency of the SWCNT coated film decreased as the coating speed increased for dip and blade coatings, but were independent of the coating speed for slot coating. All three coating methods were able to produce transparent conductive film with transparency above 85% and sheet resistance close to 1000 ohm/sq. For industrial production, the slot die coating method appears to be more suitable in terms of high coating speed and uniformity of optical and electronic properties.

A statistical mechanics model of carbon nanotube macro-films

Carbon nanotube macro-films are two-dimensional films with micrometer thickness and centimeter by centimeter in-plane dimension.These carbon nanotube macroscopic assemblies have attracted significant attention from the material and mechanics communities recently because they can be easily handled and tailored to meet specific engineering needs.This paper reports the experimental methods on the preparation and characterization of single-walled carbon nanotube macro-films,and a statistical mechanics model on the deformation behavior of this material.This model provides a capability to optimize the synthesis process by comparing with the experiments.

Impacts of Parameter Scaling for Low-Power Applications Using CNTFET （Carbon Nanotube Field Effect Transistor） Models： A Comparative Assessment

This paper provides an extension to the earlier work wherein a comparison between different models that had studied the effects of several parameters scaling on the performance of carbon nano tube field-effect transistors was presented. The evaluation for the studied models, with regard to the scaling effects, was to determine those which best reflect the very essence of carbon nano-tube technologies. Whereas the models subject this comparison （Fettoy, Roy, Stanford, and Southampton） were affected to varying degrees due to such parametric variations, the Stanford model was shown as still being valid for a wide range of chiralities and diameter sizes; a model that is also applicable for circuit simulations. In this paper, we present a comparative assessment of the various models subject to the study with regard to the effect of incorporating multiple carbon nanotubes in the channel region. We also assess the effect of oxide thickness on transistor performance in terms of the supply voltage threshold effects. Results leveraging our findings in this ongoing research endeavor reveal that many research efforts were not efficient to high degree due to high delay and not valid for circuit simulations.