Search

Abstract: Carbon nanotubes are synthesized on the silicon nanowire arrays which are fabricated on silicon substrate by chemical vapor depositing SiCl4 and H2 gases in the presence of Au catalysts. The silicon nanowires are single-crystal with lengths up to 100μm and diameters ranging from 50 to 500nm. The tangled carbon nanotubes are grown directly from the surface of Si nanowires. The field emission properties of the carbon nanotubes are investigated at the gap of 200μm. The low turn on and threshold fields are obtained. The stabilization of the emission currents is also presented. [Copyright &y& Elsevier]

Efficient heat transfer control is highly demanded for dynamic thermal management of equipment and buildings especially when the environmental temperature dramatically changes. Thermal switches, the current approach of heat transfer control, suffer from the issues of low switching ratios below eight and sharp state transition between "on" and "off". Herein, a continuously‐tuned thermal regulator with an ultrahigh thermal‐conductivity change ratio of 43 based on superaligned carbon nanotube aerogel is reported, which works on the regulation of both thermal interfacial resistance and conduction pathways by compressive deformation‐induced microstructure evolution. This thermal regulator can stabilize the device temperature at 25 °C when the environmental temperature varies by 7 and 11 °C under the natural convection and forced convection conditions, respectively. Toward practical application, the thermal regulator with flexibility is wrapped around a cylindrical lithium‐ion battery to control the operation temperature within the optimal range of 20–40 °C for enhanced discharging performance even at an environmental temperature of −20 °C. Besides, by combining the thermal regulator with radiative cooling film, the house model temperature can be lowered by 2.7 °C during daytime and raised by 1.1 °C during nighttime compared with the bare one. This efficient thermal regulation approach offers an effective solution for practical thermal management. [ABSTRACT FROM AUTHOR]

Reports on the synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates. Methods; Results; Conclusions.

Presents research in which gallium nitride nanorods were prepared through a carbon nanotube reaction. The reaction of Ga2O vapor with NH3 gas to form wurtzite gallium nitride nanorods; Proposed idea that the carbon nanotube acts as a template to confine the reaction; The possibility of synthesizing other nitride nanorods through similar carbon nanotube-confined reactions.

The carbon nanotube (CNT) is a compelling and promising material for industrial applications requiring high strength and rigidity. For a multi-walled CNT (MWCNT), the nominal tensile strength and Young's modulus (considering the whole cross-sectional area of the specimen) are key mechanical factors for the practical application of macroscopic fibers and composites. However, the nominal tensile strength and Young's modulus of MWCNTs are much lower than their effective tensile strength and Young's modulus (considering the fracture cross-sectional area) because the outermost graphite layer always fractures first due to the low cross-link between graphite layers. In this paper, we fabricated the carbon nanofibers (CNFs) by epitaxial growth on super-aligned MWCNT film template and conducted in situ uniaxial tensile tests on individual carbon-nanotube-templated CNFs. The individual CNFs show improved nominal mechanical performance than previously reported MWCNTs. The nominal mechanical properties enhancement of the CNFs is attributed to the effective control on load transfer between interwalls. [ABSTRACT FROM AUTHOR]

The polysulfide (PS) dissolution and low conductivity of lithium sulfides (Li2S) are generally considered the main reasons for limiting the reversible capacity of the lithium‐sulfur (Li‐S) system. However, as the inevitable intermediate between PSs and Li2S, lithium disulfide (Li2S2) evolutions are always overlooked. Herein, Li2S2 evolutions are monitored from the operando measurements on the pouch cell level. Results indicate that Li2S2 undergoes slow electrochemical reduction and chemical disproportionation simultaneously during the discharging process, leading to further PS dissolution and Li2S generation without capacity contribution. Compared with the fully oxidized Li2S, Li2S2 still residues at the end of the charging state. Therefore, instead of the considered Li2S and PSs, slow electrochemical conversions and side chemical reactions of Li2S2 are the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li‐S batteries. [ABSTRACT FROM AUTHOR]

The polysulfide (PS) dissolution and low conductivity of lithium sulfides (Li2S) are generally considered the main reasons for limiting the reversible capacity of the lithium‐sulfur (Li‐S) system. However, as the inevitable intermediate between PSs and Li2S, lithium disulfide (Li2S2) evolutions are always overlooked. Herein, Li2S2 evolutions are monitored from the operando measurements on the pouch cell level. Results indicate that Li2S2 undergoes slow electrochemical reduction and chemical disproportionation simultaneously during the discharging process, leading to further PS dissolution and Li2S generation without capacity contribution. Compared with the fully oxidized Li2S, Li2S2 still residues at the end of the charging state. Therefore, instead of the considered Li2S and PSs, slow electrochemical conversions and side chemical reactions of Li2S2 are the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li‐S batteries. [ABSTRACT FROM AUTHOR]

Non‐dispersive infrared (NDIR) gas monitoring has advantages of environment stability, convenient operation and maintenance, wide detection range, and multi‐gas‐detection capability. However, the conventional IR sources for NDIR gas monitoring, such as miniature lamps, microelectromechanical system (MEMS) light sources, and light‐emitting diodes (LEDs), can only work at narrow modulation frequency and spectral range, or require complicated design and fabrication, because of the constraint of materials and work principle. These issues cause low data acquisition rate, poor anti‐interference ability and limited gas compatibility to NDIR. Here, the super‐aligned carbon nanotube (SACNT) film is developed as an IR source in NDIR gas monitoring system. It has a wide spectral range (0.2–334 µm), a facile fabrication method, and can work up to a high frequency ≈150 kHz. A mechanical‐chopper‐free and wide‐concentration‐range monitoring equipment for CO2 and CH4 greenhouse gases is demonstrated with SACNT film IR source. The concentration ranges for CO2 and CH4 investigated in this paper are 0.0195–20.10% (v/v) and 0.10–17.11% (v/v), respectively. It can be easily applied to monitor other kinds of gases as well. [ABSTRACT FROM AUTHOR]

As the semiconductor industry enters the post‐Moore era, reconfigurability on the device level, that incorporates multifunction in a device unit to realize more complex systems with more compact logic gates, is a promising methodology to extend the development of integrated circuit industry. Here, a reconfigurable carbon nanotube (CNT) barristor is developed on the basis of a Schottky barrier (SB) CNT transistor. The device shows a significant rectifying characteristic and can be reconfigured to a forward rectifying mode or a backward rectifying mode by applying an appropriate gate voltage. The reconfigurability originates from the ambipolar characteristics of the CNT channel, and the rectification behaviors can be attributed to the drain‐induced self‐gating effect. Additional experiments reveal that it is the interfacial charge redistribution that plays the role of an additional gate on the SB near the drain. A gate‐controllable half‐wave rectifier has been fabricated by using the reconfigurable CNT barristor. The CNT barristor brings new functions to CNT electronic devices and also opens up a new methodology for future reconfigurable device design. [ABSTRACT FROM AUTHOR]

Abstract: The carbon nanotube/polyaniline (CNT/PANI) composites have important potential applications as the electrodes in energy storage devices for their attractive electrochemical properties. In this work, we report a novel method to prepare the interesting paper-like CNT/PANI composites by using the CNT network as the template. Compared with the conventional brittle CNT/PANI composites, these paper-like composites were much thin and flexible. This work demonstrates a new approach, which may transform a brittle polymer into flexible films. Meanwhile, these film electrodes showed much superior electrochemical performance such as higher specific capacitance, lower internal resistivity, and more stability under different current loads. These paper-like composite electrodes have promising applications in new kinds of energy storage devices. [Copyright &y& Elsevier]

Cross‐linked polyethylene glycol‐based resin (c‐PEGR) is constructed by a ring‐opening reaction of polyethylene glycol diglycidyl ether (PEGDE) with epoxy groups and polyether amine (PEA) with amino groups. By confining the hydroxyl groups with inferior oxidative stability to the c‐PEGR backbone, the oxidation potential of the PEG‐based polymer material with reduced reactivity is boosted to 4.36 V. The c‐PEGR based gel electrolyte shows excellent flexibility, lithium‐ion transport, lithium compatibility, and enhanced oxidation stability, and is successfully applied to a 4.35 V lithium cobaltate (LCO)||lithium (Li) battery system. A quasi‐static linear scanning voltammetry (QS‐LSV) method is proposed for the first time to accurately measure the oxidation potential and electrochemical stability window of materials with low conductivities such as polymers, which possesses the advantages of high accuracy and short test time. This work provides new insights and research techniques for selecting polymer electrolytes for high‐voltage flexible lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

Cross‐linked polyethylene glycol‐based resin (c‐PEGR) is constructed by a ring‐opening reaction of polyethylene glycol diglycidyl ether (PEGDE) with epoxy groups and polyether amine (PEA) with amino groups. By confining the hydroxyl groups with inferior oxidative stability to the c‐PEGR backbone, the oxidation potential of the PEG‐based polymer material with reduced reactivity is boosted to 4.36 V. The c‐PEGR based gel electrolyte shows excellent flexibility, lithium‐ion transport, lithium compatibility, and enhanced oxidation stability, and is successfully applied to a 4.35 V lithium cobaltate (LCO)||lithium (Li) battery system. A quasi‐static linear scanning voltammetry (QS‐LSV) method is proposed for the first time to accurately measure the oxidation potential and electrochemical stability window of materials with low conductivities such as polymers, which possesses the advantages of high accuracy and short test time. This work provides new insights and research techniques for selecting polymer electrolytes for high‐voltage flexible lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

Aluminum borate (Al4B2O9) nanowires are synthesized by directly heating a mixture of Al and B2O3 powder at 850 °C. The nanowires synthesized are single-crystal with lengths about several micrometers and diameters ranging from 20 to 100 nm. The transmission electron microscopy (TEM) images show that Al particles are at the tips of some nanowires, which indicates a vapor–liquid–solid (VLS) growth mechanism. Boron oxide dissociates metal Al powder to prevent it from aggregating and simultaneously reacts with aluminum to produce aluminum borate. A self-catalytic growth mechanism of the aluminum borate nanowires is proposed. [Copyright &y& Elsevier]

We report the design and simple spray coating fabrication process of a perfect absorber based on carbon nanotubes (CNTs) and carbon black particles with omnidirectional high absorption efficiency beyond 99.9% over the broad wavelength range from 400 nm to 20 μm. The carbon black particles are introduced into the CNT solution to form multi-scale all-carbon-based nanomaterials, effectively modifying the morphology of the sprayed layer to improve the light absorption. The promising absorption characteristics of the CNT–carbon black layer are attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trap light. In addition to serving as absorbers in the coating layer, the CNTs, more importantly, act as connectors between carbon black particles for absorber preparation at a large scale, which is the key to modifying the surface morphology. The all-carbon-based coating layer is also shown to be effective for solar thermal harvesting and self-cleaning function. The developed mixing method for CNTs and carbon black particles in solutions opens a new path for the realization of multi-functional sprayed layers based on CNTs and advances the technology of CNT coatings for scale-up to industry applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium metal anodes have a high theoretic capacity and are considered the promising electrodes for high energy density rechargeable batteries. However, the uneven deposition of lithium and lithium dendrites hinders the practical usage of lithium metal anodes. In order to solve this problem, carbon nanotube aerogels coated with amorphous carbon (AC@CNT aerogels) are used as the host, and molten lithium infuses into the carbon aerogels to obtain composite lithium metal anodes. The self-standing, porous AC@CNT aerogels provide a solid structure for lithium deposition/stripping and effectively reduce the local current density, so that lithium dendrites are suppressed and better electrochemical performances are achieved. Compared with the bare lithium metal anodes, the AC@CNT aerogel/lithium metal (AC@CNT/Li) anodes exhibit a longer cycling life of 500 h at deposition/striping capacity of 1 mAh cm−2 on symmetric cells, better cycling performance of 152 mAh g−1 at 0.1C in lithium cobalt oxide/lithium (LCO/Li) cells, and 120.3 mAh g−1 at 1 C in lithium iron phosphate/Li (LFP/Li) cells, demonstrating the potential of the AC@CNT/Li electrodes in developing high-performance lithium-metal batteries. Composite lithium anodes are fabricated by infiltrating molten lithium into amorphous carbon-coated carbon nanotube (AC@CNT) aerogels via thermal infusion. The AC@CNT aerogels significantly improve lithium deposition/stripping behavior. The AC@CNT/Li electrode exhibits better electrochemical performances in both symmetric and lithium cobalt oxide/lithium cells than the bare lithium metal anode, demonstrating its potential in developing high-performance lithium batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

By using superaligned carbon nanotube (SACNT) macrostructures as reinforcements, the one-step homoepitaxial growth of SACNT/graphite composites was achieved with a home-built experimental setup at temperatures as high as 2600 °C. Compared with traditional furnace heating method, this approach offers the advantages of increased convenience, high throughput and energy efficiency. This high-temperature homoepitaxy strategy was applied to three kinds of structures: SACNT yarn, SACNT film, and SACNT array. Because of the high temperature which exceeded 1800 °C, the samples after high-temperature homoepitaxy showed increased G/D peak area ratios in the Raman spectra, enhanced mechanical properties and improved thermal properties, all of which can meet the requirements of various applications. Image 1 • Three kinds of superaligned carbon nanotube (SACNT) structures are used for macroscopic continuity and manipulation. • The SACNT/graphite composite has been fabricated in a home-built experimental setup by self-heating up to 2600℃. • One-step fulfilment of both carbon deposition and simultaneous graphitization leads to convenience and energy efficiency. • Samples after high-temperature homoepitaxy exhibit increased G/D ratio in Raman spectra and superior material performance. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) are van der Waals layered materials with sizable and tunable bandgaps, offering promising platforms for two-dimensional electronics and optoelectronics. To this end, the bottleneck is how to acquire high-quality single crystals in a facile and efficient manner. As one of the most widely employed methods of single-crystal growth, conventional chemical vapor transport (CVT) generally encountered problems including the excess nucleation that leads to small crystal clusters and a slow growth rate. To address these issues, a seed crystal is introduced to suppress the nucleation and an inner tube is adopted as both a separator and a flow restrictor, favoring the growth of large-sized and high-quality TMD single crystals successfully. Three examples are presented: the effective growth of millimeter-sized MoSe2 and MoTe2 single crystals, and the greatly shortened growth period for a PtSe2 single crystal, all of which are synthesized in high quality according to detailed characterization. The mechanism of seeded CVT is discussed. Furthermore, a phototransistor based on exfoliated multi-layered MoSe2 displays an excellent photoresponse under ambient conditions, and considerably rapid rise and fall times of 110 and 125 μs are obtained, which might be contributed by the good crystallinity of the as-grown crystal. This work paves the way for developing a facile and versatile method to synthesize high-quality TMD single crystals in the laboratory. [ABSTRACT FROM AUTHOR]

Three dimensional TiO 2 –Au cross-nanoporous structure (3D TiO 2 –Au CNS) as an efficient photoelectrocatalytic system was fabricated using superaligned carbon nanotube films as etching masks and electron-beam evaporation. The 3D TiO 2 –Au CNS exhibited a broad absorption band in the visible region, and the incident photon-to-current conversion efficiency of 3D TiO 2 –Au CNS/Ti electrode was 3–4 times higher than that of pure TiO 2 electrode. The photocurrent density of the 3D TiO 2 –Au CNS device was 0.079 mA cm−2 at 0 V vs. Ag/AgCl with a solar irradiance of 100 mW cm−2. This developed preparation method was simple, of high flexibility and can be adopted for mass production due to its low cost and good compatibility with other processing technologies. The 3D TiO 2 –Au CNS and its preparation method have important value in design of photoelectrocatalytic system for research and practical applications, which may have a potential utility in photocatalytic and other photoelectrocatalytic reactions. Image 1 • 3D TiO 2 –Au CNS was fabricated by SCNT films as masks and electro-beam evaporation. • The photocatalytic performance of thin-layer TiO2 is improved in this structure. • Porous Ti substrate and Au NPs can accelerate the charge separation and transfer. • The photocurrent density of the structure was 0.079 mA cm−2 at 0 V vs. Ag/AgCl. • The preparation method is simple, flexible and can be used for mass production. [ABSTRACT FROM AUTHOR]

A strategy to produce sulfur (S) cathodes with ultrahigh areal capacity for lithium-sulfur (Li–S) batteries is proposed. Porous carbon nanotube (CNT) aerogel@Li 2 S 8 cathodes are obtained by dropping Li 2 S 8 solution into the CNT aerogels that are prepared through a freeze-drying method. The three-dimensional (3D) porous structure of the CNT aerogel provides a complete electron transport network and rapid ion transport channels. Moreover, the rich mesoporous structure has an extreme capillary action on the electrolyte. Numerical simulation shows that in a surprisingly short time (2 μs), the electrolyte can be absorbed into the mesopores by capillary action and reach a stable state, limiting the "shuttle effect" of polysulfides. Based on these unique characteristics, the CNT aerogel@Li 2 S 8 cathode exhibits excellent electrochemical performance. With an extremely high areal S loading of 20 mg cm−2, the cathode shows an ultrahigh areal specific capacity of 22.9 mAh cm−2. For the pouch cell with an areal S loading of 10 mg cm−2 and a low electrolyte/sulfur (E/S) ratio of 7.8 μL mg−1, the areal specific capacity reaches a high value of 10.4 mAh cm−2. Image 1 [ABSTRACT FROM AUTHOR]

The transport property of six types of individual carbon nanotubes (CNT) with specified chiral indices at high temperature is investigated on a home‐made apparatus. It is found that the resistivity of all individual CNTs increases with temperature monotonically, whereas the mobility decreases with temperature and follows different laws in different temperature ranges. The carrier concentration increases exponentially with −1/T. The mobility of CNT deviates from traditional trends with temperature, T−β, at high temperature (1070–1728 K). This deviation is attributed to scattering with optical phonons at high temperature. The data show that the electron‐optical phonon interaction becomes dominant in the temperature range of 1070–1362 K for all measured CNTs. Finally, result within a polaron model is discussed. [ABSTRACT FROM AUTHOR]

High‐temperature thermionic electron emission from different types of individual suspended carbon nanotubes (CNTs) in a homemade chip is studied. When collecting emission electrons with an external electrode, it is found that the collecting electric field influence the transport current in the CNTs, and the thermionic electron emission deviated from the traditional thermionic electron emission model and cannot reach "saturation". This effect is analyzed for single‐walled, double‐walled, multiwalled‐CNT and CNT bundles. It is found that this effect show correlation with the conductivity and diameter of the CNT. With the increase in metallicity, the influence of collecting electrode is gradually weakened. Also, the effect shows a negative correlation with the diameter of CNTs. An equation is proposed to describe the measured thermionic emission curve and determine the "effective" work function of the CNT. [ABSTRACT FROM AUTHOR]

Self-organized conical microstructures are fabricated by 308 nm XeCl excimer laser irradiation of cyanoacrylate-carbon nanotube composites in air. The morphology of the surface on the composite films is studied, varying the total number and fluence of the applied laser pulses. A simple mechanism of the fabrication based on the evaporation of cyanoacrylate and the burning of carbon nanotubes is proposed. The conical peak structures of cyanoacrylate-carbon nanotube composite films show good field-emission properties. Similar structures are also observed on carbon nanotube arrays. [ABSTRACT FROM AUTHOR]

Novel Raman scattering in polar semiconductor SiC and TaC one-dimensional materials have been carried out. With increasing incident laser wavelength from 488 to 633 nm there is a huge difference in Raman intensity enhancement for the LO/IF peaks and the TO peak. This has been interpreted as due to Fro¨hlich interaction and abundant defects in polar nano-scale semiconductor materials. [Copyright &y& Elsevier]

We report the design and simple fabrication process of a perfect absorber based on carbon nanotube films, which enable omnidirectional high absorption efficiency over the wavelength range from 250 nm to 20 μm with polarization independence. The absorber is fabricated using layers of super-aligned carbon nanotube (SACNT) films assembled in a unique manner, which could be easily prepared on stretchable or rigid substrates or suspended. The promising absorption characteristics of the SACNT films were attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trapped light. Moreover, the absorber and its fabrication method exhibit excellent compatibility with various composed materials and treatment processes. Through combination with ultraviolet-curable resist, a robust, ultrathin, and ultralight absorber with good mechanical properties was fabricated on stretchable substrates. The developed fabrication method opens a new path to realize high absorption performance using carbon nanomaterials and the obtained absorber has broad prospects in aerospace and military applications. Image 1 [ABSTRACT FROM AUTHOR]

Current artificial tactile sensors mostly exploit a variety of electron‐related physical mechanisms to obtain high sensitivity and low detection force. However, these mechanisms are still distinct from the ion‐related biological processes of human's tactile sensation, and are therefore away from the goal of bionic applications. In the past few years, only several types of ionic tactile sensors have been proposed, and they are still subject to low sensitivity. Here, a novel type of ultrasensitive hydrogel tactile sensor is reported based on asymmetric ionic charge injection as the working mechanism, named as asymmetric ionic sensing hydrogel (AISH). With a small external working voltage of only tens of millivolts, these AISH devices show an extremely low detection force of 0.075 Pa, ultrahigh sensitivity of 57–171 kPa−1, and excellent cycling reliability upon pressing. Applications of these ultrasensitive tactile sensors in fingerprint identification of voice, monitoring of pulse waves, and detection of underwater wave signals are experimentally demonstrated. Combining the merits of simple fabrication process, ionic‐type detection mechanism, and ion injection procedure, such AISH sensors not only reveal a new strategy toward highly sensitive tactile sensors, but also show realistic potential applications in future wearable electronic and bioelectronic devices. [ABSTRACT FROM AUTHOR]

Photodetectors based on two-dimensional (2D) transition metal dichalcogenides (TMDs) can only be operated in a single photovoltaic or photoconductive mode, showing either high detectivity or high responsivity, but not both. An effort to develop a photodetector that can dynamically switch its working mode is indispensable for practical applications. In this article, we demonstrate a high performance, phase-transition modulated, dual-mode photodetector based on WSe2/VO2 heterojunction. Enabled by the insulator-to-metal transition of VO2, the WSe2/VO2 heterojunction can be regulated from a type-II heterojunction to a Schottky junction, showing a tunable built-in electric field at the heterojunction interface. This resulted in the dynamic switch of carrier transport and photoresponse in the heterojunction. With this dual-mode function, the new photodetector can have both a high detectivity and a large responsivity, surpassing the current performance of single mode 2D TMDs photodetectors. With a direct laser writing and erasing technique, the photoresponse of a WSe2/VO2 device can be locally modulated as desired. This dual mode detection of the WSe2/VO2 photodetector deepens the fundamental understanding of charge transfer in heterojunctions and favors versatile applications in photodetection. [ABSTRACT FROM AUTHOR]

The thermoacoustic response of carbon nanotube (CNT) thin films at frequencies ranging from 300 Hz up to 100 kHz has been studied in a variety of gaseous mediums. Theoretical derivations show that the sound pressure generated by CNT thin films is approximately proportional to the inverse of the heat capacity of the gas within the audible frequency range of human hearing, which is consistent with the experimental results in argon, air, and helium. For large size CNT films, a decrease in sound pressure is observed within a higher frequency range in air, which is attributed to the destructive interference of sound waves in the near field zone according to the theoretical calculations. [ABSTRACT FROM AUTHOR]

Abstract Polyimide (PI) is a high-performance polymer with ultrahigh heat stability while carbon nanotube (CNT) possesses high mechanical strength, excellent electrical and thermal conductivity. Here we report a facile and low-cost method free from CNT pre-dispersion for fabricating super-aligned carbon nanotube (SACNT)/PI composite film which combines the advantages of both SACNT and PI. Flexible and scratch-resistant composite film with high CNT content, uniform dispersion of CNTs, and controlled patterned CNT structures can be fabricated easily via in situ imidization. The SACNT/PI composite film exhibits improvement in mechanical strength, Young's modulus, electrical conductivity compared with pristine PI, and shows good thermal stability. Thanks to these superb properties, a flexible, stable, addressable, electromagnetic wave permeable, and high-temperature fast-response multifunctional heater as well as a thermo-mechanical actuator based on SACNT/PI composite film have been demonstrated in this paper. And it also shows great potential in a variety of applications such as flexible/wearable electronics, RFID, other thermo-related devices and so on. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Ultrathin and cross-stacked carbon nanotube (CNT) films modified with hafnium oxide (HfO 2) by atomic layer deposition are employed as efficient polysulfide barriers for high performance Li-S batteries. A HfO 2 /CNT interlayer has an ultrathin, flexible structure with a thickness of 1.5 μm and an areal density of 0.087 mg cm−2, along with excellent wettability to electrolyte. The highly conductive CNT network and the catalytic surface adsorption of polysulfide species by HfO 2 significantly suppress the polysulfides shuttling phenomenon. With high sulfur loadings of up to 75 wt%, electrodes incorporating a HfO 2 /CNT interlayer show noticeable improvements in various electrochemical properties, including long-term cycling stability (721 mA h g−1 after 500 cycles at 1 C), high rate performance (800 mA h g−1 at 5 C), favorable anti-self-discharge capabilities, and suppression of Li anode corrosion. These results suggest a new and efficient polysulfide trapping material and a viable configuration for high-performance Li-S batteries. Graphical abstract An ultrathin HfO 2 /CNT interlayer is used as an efficient polysulfide barrier to improve the performance of Li-S batteries. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Developing hybrid supercapacitor-battery energy storage devices for applications in electric vehicles is attractive because of their high energy density and short charge/discharge time. In this study, flexible MnO 2 nanoparticle-coated air-oxidized carbon nanotube (MnO 2 /aCNT) electrodes are fabricated by the in situ redox reaction of KMnO 4 and aCNTs at room temperature. The MnO 2 nanoparticles have diameters of ∼10 nm. There is a strong chemical interaction between the MnO 2 active material and aCNTs as a result of the Mn–O–C linkage. The flexible aCNT network can alleviate the strain from the MnO 2 volume change and maintain the electrode integrity during rapid charge/discharge. The aCNT framework also provides a continuous and rapid electron pathway and ensures uniform dispersion of the MnO 2 nanoparticles. The presence of MnO 2 nanoparticles provides short pathways for Li-ion diffusion and allows interfacial capacitive lithium storage for ultrafast and reversible lithium storage. We report the best high-current performance to date for MnO 2 /C electrodes, of 395.8 mA h g−1 at 10 A g−1, and 630.2 mA h g−1 after 150 cycles at 2 A g−1. The excellent electrochemical performance, combined with the capacitive dominating process of the electrode, will further the design of high-performance hybrid supercapacitor-battery energy storage devices. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Vertically aligned carbon nanotube array/SiC composites (VACNT/SiCs), fabricated through chemical vapor infiltration (CVI) of SiC ceramics into the CNT arrays, have unique porous microstructures and microscopic properties along with internal CVI SiC gradient from surface to inside. The internal nanoindentation properties including modulus and hardness were characterized to be related to the CVI depths in horizontal and vertical directions, as compared to the external surface nanoindentation properties in the longitudinal and transverse directions. Results showed that the modulus and hardness of the VACNT/SiCs from surface to inside decreased linearly with the CVI depths. Besides, the fitting slopes of modulus with different CVI depths in the vertical and horizontal directions were nearly equal, but the fitting slope of hardness in the vertical direction was almost twice that in horizontal direction. Therefore, it can be indicated that the CVI deposited SiC gradient gives rise to reduction in both modulus and hardness, and has a larger effect on the latter which is mainly upon the deposited SiC quantity and density. Comparatively, the modulus along the external surface in the longitudinal was twice that in the transverse directions, 31.2 and 16.8 GPa, respectively. And the hardness in the longitudinal and transverse directions was nearly the same, 0.627 and 0.597 GPa. It can be inferred that the modulus of the VACNT/SiCs along the external surfaces shows anisotropy due to the CNT modulus anisotropy. Nevertheless, the hardness along the external surfaces was the nearly same, resulting from equally deposited SiC coating on all over the surfaces of composites. [ABSTRACT FROM AUTHOR]

We have studied the transmission of carbon nanotube film with ultrathin oxide coatings in the visible light range. It is found that the transmission is improved after coating. This is mainly due to Rayleigh scattering induced by the ultrathin oxide coatings. The improvement of the visible light transmission has important applications for a mobile phone touch screen. [ABSTRACT FROM AUTHOR]

Ultrathin and lightweight MoS 2 /carbon nanotube (CNT) interlayers are developed to effectively trap polysulfides in high-performance lithium–sulfur (Li–S) batteries. The MoS 2 /CNT interlayer is constructed by loading MoS 2 nanosheets onto a cross-stacked CNT film. The CNT film with excellent conductivity and superior mechanical properties provides the Li–S batteries with a uniform conductive network, a supporting skeleton for the MoS 2 nanosheets, as well as a physical barrier for the polysulfides. Moreover, chemical interactions and bonding between the MoS 2 nanosheets and the polysulfides are evident. The electrode with the MoS 2 /CNT interlayer delivers an attractive specific capacity of 784 mA h g −1  at a high capacity rate of 10 C. In addition, the electrode demonstrates a high initial capacity of 1237 mA h g −1 and a capacity fade as low as −0.061% per cycle over 500 charge/discharge cycles at 0.2 C. The problem of self-discharge can also be suppressed with the introduction of the MoS 2 /CNT interlayer. The simple fabrication procedure, which is suitable for commercialization, and the outstanding electrochemical performance of the cells with the MoS 2 /CNT interlayer demonstrate a great potential for the development of high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

The fabrication of high-performance cathodes with high sulfur content is essential for the practical realization of lithium–sulfur (Li–S) systems. The preparation of high-sulfur-content electrodes is currently hindered by poor dispersion of the conductive agents; nonuniformly distributed conductive agents cannot provide sufficient sulfur-loading sites, thereby resulting in aggregation of sulfur/Li 2 S and severe polarization. To deal with this issue, we prepare CO 2 modified carbon nanotube (CNT)-based cathodes for Li–S batteries. CNTs are exposed to CO 2 at 900 °C, resulting in uniformly distributed negative charges on the external surface of the tubes; the electrostatic repulsion facilitated the dispersion of CNTs. Compared with the previous work on CNTs prepared by air oxidation (denoted as air-CNTs), the dispersions of the CO 2 -treated CNTs (denoted as CO 2 -CNTs) are more stable, which allows higher sulfur loading and improves sulfur utilization. A free-standing CO 2 -CNT&S electrode with a sulfur content of 80 wt% is fabricated through a sonication-assisted method. The excellent dispersion of the CO 2 -CNT&S network results in little kinetic barriers, low polarization, and fast charge transport at the interface of the electrode and electrolyte. The CO 2 -CNT&S electrode delivers a lower capacity fading rate and superior rate performance compared with the air-CNT&S electrode. [ABSTRACT FROM AUTHOR]

Rapidly Modulated Wide-Spectrum Infrared Source Made of Super Aligned Carbon Nanotube Film for Greenhouse Gas Monitoring (Adv. Funct. Gas monitoring, NDIR, rapid modulated IR sources, SACNT films, wide-spectral ranges The SACNT film light source is expected to monitor other different kinds of gases in complex environments. [Extracted from the article]

Cross-stacked super-aligned carbon nanotube (SACNT) films are promising for use as current collectors in lithium-ion batteries because of their outstanding capability to decrease the weight and thickness of inactive material and strong adhesion to the electrodes. However, the relatively poor conductivity of SACNT films may limit their application to large-size electrodes or at high current rate. Herein, a facile approach is proposed to improve the conductivity of SACNT films by electron-beam deposition of a thin metal film on their surface. Such modification lowers the sheet resistance by three orders of magnitude while keeping the extremely small fraction of SACNT current collectors. The metal-coated SACNT films strongly inhibit polarization during the electrochemical reaction, resulting in improved cell performance compared with that of metal and uncoated CNT current collectors. The improvement in conductivity and cell performance achieved by this approach is so large that the effect of the increase of inactive material is overwhelmed, leading to increased gravimetric energy density. [ABSTRACT FROM AUTHOR]

Ultrathin MnO2/graphene oxide/carbon nanotube (G/M@CNT) interlayers are developed as efficient polysulfide-trapping shields for high-performance Li-S batteries. A simple layer-by-layer procedure is used to construct a sandwiched vein-membrane interlayer of thickness 2 µm and areal density 0.104 mg cm−2 by loading MnO2 nanoparticles and graphene oxide (GO) sheets on superaligned carbon nanotube films. The G/M@CNT interlayer provides a physical shield against both polysulfide shuttling and chemical adsorption of polysulfides by MnO2 nanoparticles and GO sheets. The synergetic effect of the G/M@CNT interlayer enables the production of Li-S cells with high sulfur loadings (60-80 wt%), a low capacity decay rate (−0.029% per cycle over 2500 cycles at 1 C), high rate performance (747 mA h g−1 at a charge rate of 10 C), and a low self-discharge rate with high capacity retention (93.0% after 20 d rest). Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy observations of the Li anodes after cycling confirm the polysulfide-trapping ability of the G/M@CNT interlayer and show its potential in developing high-performance Li-S batteries. [ABSTRACT FROM AUTHOR]

High-performance actuators have been studied for many years, as they can be used in the fields of artificial muscles, optical switches and biomimetic applications. However, previous actuators mostly had single colors. Actuators with switchable optical properties are still rare. Here, we propose a transparency-switchable actuator based on single-layer superaligned carbon nanotube sheet and paraffin-polydimethylsiloxane composite. When a voltage is applied, the transmittance of the actuator changes from 0.7% to 67% (at the wavelength of 550 nm). At the same time, it bends obviously with a displacement up to 8.4 mm. The actuator is also durable, demonstrating both reversible actuation phenomenon and repeatable switchable transparency for 100 cycles. In addition, since this new type of actuator demonstrates optical property changing together with actuation process, which is smarter compared to previous conventional actuators, a smart window is fabricated, indicating its application in personal privacy protection and intelligent household devices. In a word, this work opens new perspectives on smart windows, optical switches and so on. [ABSTRACT FROM AUTHOR]

Laser lift off (LLO) was one of the most essential processes in fabrication of vertical GaN-based LEDs. However, traditional laser lift off of GaN on sapphire substrates needed high laser energy threshold, which deteriorated the GaN crystal. In this paper, it was found that inserting carbon nanotube between GaN and sapphire could effectively reduce the laser energy threshold in GaN LLO, from 1.5 J / cm 2 of conventional GaN/sapphire to 1.3 J / cm 2 of CNT inserted GaN/sapphire. The temperature distributions at the GaN/sapphire interfaces with and without CNTs were simulated by the finite elements calculation under laser irradiation. It was found that, due to the higher laser absorption coefficient of CNT, the CNT played as a powerful heating wire, sending out the thermal outside to elevate the GaN's temperature, and thus reduce the laser threshold for LLO. Raman and photoluminescence measurements indicated that residual stress of GaN membranes was as small as 0.3 GPa by the carbon nanotube assisted LLO. This work not only opens new application of CNTs, but also demonstrates the potential of high performance blue and green LEDs. [ABSTRACT FROM AUTHOR]

We have systematically studied the radiation effects on both p-type and n-type single-walled carbon nanotube (SWCNT) thin film transistors (TFTs) using aligned CNT arrays and semiconducting CNT networks as conductive channels. The main electrical parameters were extracted and studied statistically to help determine both the radiation effects and the underlying physical mechanisms. We found that the predominant factors affecting the total ionizing dose (TID) effects in SWCNT-based TFTs are the carrier doping effect of the air molecules for p-type TFTs, the electron doping effect of the fixed charges for n-type TFTs, and the junction contact improvement for CNT-network TFTs. As a result, specific methods were proposed to act as guidelines to eradicate the corresponding causes and improve the radiation hardness performance of SWCNT-TFTs, e.g. by optimizing the shield or insulator materials, preliminary radiation treatments and raw CNT materials selection for future application of SWCNT-based complementary metal-oxide-semiconductor (CMOS) devices. In contrast, we can also use the radiation method to control the threshold voltages of the SWCNT-TFTs quantitatively according to our experiments. Additionally, we designed and fabricated radiation-stable ambipolar SWCNT-TFTs for assembly of CMOS-like logic inverters, which showed high-radiation hardness performances up to a TID of 5000 krad (Si). [ABSTRACT FROM AUTHOR]

Recently, actuating materials based on carbon nanotubes or graphene have been widely studied. However, present carbon-based actuating materials are mostly driven by a single stimulus (humidity, light, electricity, etc.), respectively, which means that the application conditions are limited. Here, a new kind of multiresponsive actuating material which can be driven by humidity, light, and electricity is proposed, so it can be used in various conditions. The fabrication is based on the simplest pencil-on-paper method, in which the pencil and paper are both low-cost and easily obtained daily materials. The actuation effect is more remarkable due to a dual-mode actuation mechanism, which leads to an ultralarge actuation (bending curvature up to 2.6 cm−1). Elaborately designed, the actuator can further exhibit a bidirectional bending actuation, which is a significant improvement compared with previous reported thermal actuators. What is more, a colorful biomimetic flower and a smart curtain are also fabricated, fully utilizing the printable characteristic of the paper and multiresponsive characteristic of the actuator. It is assumed that the newly designed actuating material has great potential in the fields of lab-on-paper devices, artificial muscles, robotics, biomimics, and smart household materials. [ABSTRACT FROM AUTHOR]

Binder-free polymer encapsulated nano sulfur/super-aligned CNT (PVP@S-SACNT) composite electrode is developed via a solution-based method. In the composite structure, PVP not only facilitates better dispersion of SACNT bundles into a 3D continuous network, but also encapsulates the sulfur nanoparticles onto the SACNT network to ensure their tight electrical connection and prevent polysulfide dissolution. Combining the advantages of the high conductive and porous SACNT network and the PVP surface modification, the PVP@S-SACNT cathode exhibits excellent cyclic stability (initial capacity of 1303 mA h g −1 and 856 mA h g −1 after 200 cycles at 1 C) and high-rate performance (590 mA h g −1 at 20 C). Moreover, the PVP@S-SACNT composite presents excellent long-term capacity stability with a capacity decay of 0.052% per cycle during 1000 charge/discharge cycles at 2 C. With these appealing performances, the PVP@S-SACNT composite becomes a promising cathode material for the next-generation rechargeable batteries. [ABSTRACT FROM AUTHOR]

A novel round shape electrothermal actuator based on a bimorph structure with a cross-stacked superaligned carbon nanotube film and polydimethylsiloxane has been designed and fabricated. The coated silver film (100 nm thickness) makes the actuator surface like a mirror. Compared with common polymer nanocomposites based electrothermal actuators, our actuator exhibits a distinctive shape change. Due to the different coefficients of thermal expansion of the two material layers, it turns into a convex shape (a concave shape on the other surface) by using low electric field strengths such as < 200 V m −1 . The curvature of the convex shape can be controlled by the voltage precisely. It can lift almost four times of its own weight. The cyclic actuation test shows the excellent stability of the actuator (over 2000 times). Owing to the advantages of low driving voltages, muscle-like responses, distinctive shape changes, mirror-like surface, stability, we think the novel actuator will have great potential usages in various applications, such as artificial muscles, optical devices, microsensors, microrobots, and so on. [ABSTRACT FROM AUTHOR]

Ultralong cycle‐life and stable Li2S‐C/Li cells can be achieved by using highly nitridated graphene and controlling both recharge capacity and voltage. [ABSTRACT FROM AUTHOR]

It is known that carbon nanotubes (CNTs) possess a high light absorption coefficient with a very broad spectrum, showing good potential for solar-thermal conversion. Bi 2 Te 3 is a typical thermoelectric material with high thermoelectric conversion efficiency. In this study, we first fabricated several simple elements based on p- and n-type Bi 2 Te 3 respectively. By integrating p- and n-type elements in series, we constructed a novel solar thermoelectric conversion device covered with 0.32 g/m 2 CNT sheets, which showed a high light absorption coefficient and generated a large short-circuit current ( I sc ) of 200 mA. The size of the cross section of each series element was 0.19×0.19 cm 2 . Thus, the short-circuit current density ( J sc ) was as high as 5520 mA/cm 2 . The open-circuit voltage ( V oc ) of the device reached 400 mV. Each element of the device displayed a power conversion efficiency (PCE) of 2.1% in the near-infrared (NIR) region by a narrow band diode laser source with light flux of 100 mW/cm 2 without using any optical or thermal concentrator. Furthermore, the device is stable, durable and capable of operating at high temperatures and thus is promising for converting sunlight into electricity. This work provides a simple and convenient approach to prepare solar-energy conversion devices for large-scale applications in the future. [ABSTRACT FROM AUTHOR]

• The mechanism of voltammetric electrochemical window measurements is explained. • The influence of testing parameters on electrochemical window measurement is analyzed. • A step voltammetry method is applied to measure the electrochemical window of Li 10 GeP 2 S 12. • The electrochemical window measurement methods of liquid and solid electrolytes are suggested. The availability of solid electrolytes promisingly boosts the energy density of lithium-ion batteries (LIBs), yet the accurate voltammetry measurement of their electrochemical windows (EWs) poses a longstanding and critical concern. In this work, the mechanism of EW measurement of electrolytes is explained using the electrical double layer theory. The influence of crucial variables in voltammetry, including the scan mode, the working electrode, and the selection of two- or three-electrode test systems is investigated. Furthermore, the step voltammetry method is proposed and applied to EW testing of the inorganic solid electrolyte Li 10 GeP 2 S 12 for the first time. Finally, suggestions for EW measurement of electrolytes are presented. The results of this work promote a comprehensive understanding and more accurate EW measurement of electrolytes, facilitating the selection of suitable solid electrolytes to match different cathodes, thus advancing the development of safer high-energy density LIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Super-aligned multi-walled carbon nanotubes (MWCNTs), which had been produced in large-scale, were oxidized by H2O2 and HNO3. The surface defects and oxygen-containing functional groups introduced during the oxidizing process were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. The surface modification of MWCNTs improved the electrochemical properties. As a result, H2O2-treated and HNO3-treated MWCNTs displayed reversible capacities of 364mAh/g and 391mAh/g, respectively, after 80 galvanostatic cycles, corresponding to 143% and 154% improvements compared with pristine MWCNTs. The rate capability was also increased. At a current density of 3500mA/g, H2O2-treated and HNO3-treated MWCNTs exhibited reversible capacities of 66mAh/g and 156mAh/g, respectively. In contrast, pristine MWCNTs were only able to deliver 27mAh/g at this current density. [Copyright &y& Elsevier]

Abstract: High-efficiency dielectrics are promising materials that may enable nanoelectronic devices, such as carbon nanotubes and graphene transistors, to reach their performance limits. A high current on/off ratio, low voltage operation, high on-current and current saturation were all realized in a chemical vapor deposition graphene transistor by using a high-efficiency ion-gel dielectric. Using a drift–diffusion device model based on the surface potential in the channel that also considers the contact resistance at the channel boundary, the output characteristics of the graphene transistor are simulated, which agrees well with the experimental data and indicates that the current saturation in the graphene channel is intrinsic ambipolar performance under low field conditions. We also demonstrate an ambipolar invertor based on these high performance graphene transistors with gain values as high as 4. [Copyright &y& Elsevier]

Abstract: Mn3O4 nanoparticles anchored on continuous super-aligned carbon nanotube (SACNT) films are synthesized by decomposition of Mn(NO3)2. In the Mn3O4/SACNT composite electrodes, SACNT film is capable of serving as both the conductive pathway and structural scaffold, therefore no binder, extra conductive agent, or current collector is needed. The electrochemical performance of the Mn3O4/SACNT composite electrode is significantly affected by the particle size of Mn3O4. With smaller particle size, the electrode displays smaller voltage hysteresis and much improved reversibility and rate capability. The Mn3O4/SACNT electrodes with particle size of Mn3O4 less than 10 nm show a capacity retention of 95% after 100 cycles at 1 C and a high rate capacity of 342 mAh g−1 at 10 C (based on the total mass of the electrode), suggesting their advantages over the commercial graphite anode and potential in practical applications. [Copyright &y& Elsevier]

Abstract: Porous Li4Ti5O12 nanoclusters with high surface area are synthesized by a facile solution-based method followed by low-temperature calcination. The Li4Ti5O12 nanoclusters present the key characteristics needed to serve as high-performance negative electrodes for lithium ion batteries, including nano-sized dimension of the Li4Ti5O12 clusters (50–100 nm) for short ion and electron transfer path, and high surface area (142 m2 g−1) with mesoporosity (pore diameter 2–6 nm) for easy access to the electrolyte and efficient ion transport. Based on these characteristics, the Li4Ti5O12 electrode delivers an initial capacity of 173 mAh g−1 at the rate of 0.5 C, comparable to its theoretical capacity. Excellent cycling stability at high rates is achieved in the Li4Ti5O12 electrode, offering potential to serve as a negative electrode material for high rate lithium ion battery applications. [Copyright &y& Elsevier]