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So far, the method of top-down preparing graphene nanoribbons by etching of carbon nanotubes (CNTs) mainly relies on the catalytic reaction of Fe, Co, and Ni nanoparticles. However, etching cannot be guaranteed along the CNT axis only. In this study, Ti 3 AlC 2 is decomposed into liquid aluminum in the dynamic magnetic flux template to catalyze the growth of multiwalled carbon nanotubes (MWCNTs). Successively, the obtained MWCNTs are etched in-situ by rutile TiO 2 particles to generate multilayered graphene nanoribbons (MLGNRs). Thus-obtained nanoribbons will create zigzag edges full of short-range order segment, demonstrating a spin glass state. This work has paved a new way for a top-down approach to create MLGNRs by tailoring MWCNTs along axis direction only using dynamic magnetic flux template. So far, the method of top-down preparing graphene nanoribbons by etching of carbon nanotubes (CNTs) mainly relies on the catalytic reaction of Fe, Co, and Ni nanoparticles. However, etching cannot be guaranteed along the CNT axis only. In this study, Ti 3 AlC 2 is decomposed into liquid aluminum in the dynamic magnetic flux template to catalyze the growth of multiwalled carbon nanotubes (MWCNTs). Successively, the obtained MWCNTs are etched in-situ by rutile TiO 2 particles to generate multilayered graphene nanoribbons (MLGNRs). Thus-obtained nanoribbons will create zigzag edges full of short-range order segment, demonstrating a spin glass state. This work has paved a new way for a top-down approach to create MLGNRs by tailoring MWCNTs along axis direction only using dynamic magnetic flux template. [Display omitted] [ABSTRACT FROM AUTHOR]

3D efficient heat dissipation is essential and critical to the high-performance thermal management systems. However, challenges remain pertaining to manufacturing controllability and consistency, as well as 3D interconnected highly thermally conducive networks. Herein, a novel heat conduction architecture featuring high uniformity and condensity was constructed by tailoring aligned and densified carbon nanotube (CNT)@graphene oxide (GO) coaxial yarn assembled via a facile and controllable roll-dip-coating strategy into an integral whole, with extraordinary 3D interconnection of aligned highly crystalline graphene nanosheets. The unique architectural features of the resulting CNT-graphene film (CGF) guaranteed adequate pathways acting as "superhighways" for rapid 3D heat transfer, thereby enabling a high-efficiency 3D heat dissipation behavior, with the in-plane and through-plane thermal conductivities reached as high as 804.9 and 63.8 W m−1 K−1, respectively. This work has shed light on new strategies for designing and fabricating 3D highly thermally conducive microstructures toward high-efficiency thermal management systems. Highly uniform and condense heat conduction architecture with extraordinary 3D interconnection of aligned highly crystalline graphene nanosheets, which is constructed by tailoring aligned and densified carbon nanotube (CNT)@graphene oxide (GO) coaxial yarn assembled via a facile and controllable roll-dip-coating strategy into an integral whole, enables adequate pathways acting as "superhighways" for rapid 3D heat transfer, thereby featuring a high-efficiency 3D heat dissipation behavior. [Display omitted] • Aligned and densified CNT@GO coaxial yarn was assembled via a facile and controllable roll-dip-coating strategy. • Highly uniform and condense CGF with extraordinary 3D interconnection of aligned highly crystalline graphene nanosheets was constructed by tailoring coaxial yarn into an integral whole. • The unique architecture of CGF enabled adequate pathways acting as "superhighways" for rapid 3D heat transfer. • CGF exhibited a high-efficiency 3D heat dissipation behavior. [ABSTRACT FROM AUTHOR]

The molybdenum disulfide (MoS 2) based nanomaterials show outstanding catalytic performance in many electrochemical sensing applications with improved catalytic and electrochemical properties. Novel electrocatalyst developments and their application for food additives monitoring are of significant interest. In this work, we have developed a novel synthesis protocol for graphitic carbon nitride nanotubes decorated MoS 2 composite (g-C 3 N 4 NTs@MoS 2) using the hydrothermal method and evaluated its electrochemical sensing performance towards vanillin (VN) determination. The electrochemical sensor was accomplished at various electrolytes and optimized parameters to get an enhanced current signal for VN detection. Under the optimized conditions, the sensor obtained wide linear ranges (0.005-458.9 µM), low limit of detection (LOD, 4 nM), and excellent sensitivity (3.48 μA μM−1 cm−2) using differential pulse voltammetry (DPV). Moreover, the practical applicability of the developed sensor was also successfully evaluated in food samples with an excellent recovery rate. [Display omitted] • Novel MoS 2 nanosheets assembled on g-C 3 N 4 nanotubes using in-situ hydrothermal method. • The composite electrocatalyst of g-C 3 N 4 NTs@MoS 2 offers a synergistic effect for enhanced electrochemical detection of VN. • The proposed sensor has better electrocatalytic activity with a wide linear range and LOD for VN detection. • The proposed sensor has potential for sensing of VN in real samples. [ABSTRACT FROM AUTHOR]

Due to their unique graphitic tubular structures, carbon nanotubes (CNTs) are chemically and mechanically stable, and thus not easily degradable, which is a major safety concern for their wide and environmentally friendly use. In this study, we report the rapid degradation of single-wall CNTs (SWNTs) into carbon dioxide at room temperature using sodium hypochlorite (NaClO) and UV-light irradiation (UV/NaClO). The results showed that SWNTs could be degraded within 1–2 h, compared with >1 week without light irradiation. No obvious light dependence was observed for SWNT degradation using monochromatic light sources at 245 nm, 365 nm, and 305 nm. Raman and Fourier-transform infrared spectroscopies and scanning electron microscopy with energy dispersive spectroscopy revealed that degradation of SWNTs involved a multi-step oxidation reaction. Irradiation of NaClO induced the formation of oxygen radicals, which reacted with SWNTs to generate epoxy and ether groups. These groups then reacted with the oxygen radicals to form carboxylic groups, which introduced defects into SWNTs. Carboxylic and/or ether groups were directly transformed to CO 2 , or into intermediate products such as ethylene glycols, as oxidation progressed. The findings improve our understanding of the stability of CNTs and demonstrate a potential route for the rapid treatment of CNT wastewater for safe handling, disposal, and risk management. [Display omitted] [ABSTRACT FROM AUTHOR]

Hierarchical structures with synergistic dielectric-magnetic compositions are highly desired for electromagnetic wave absorption and interference shielding applications. Fabricating lightweight and high-performance electromagnetic protection composites with additional functions are demanded to suppress severe electromagnetic radiation and interference pollution. Herein, a unique three-dimensional hierarchical structure consisting of 1D multi-walled carbon nanotubes anchored on 1D MXene@CF core-sheath microrods are rationally proposed via electrostatic self-assembly and hydrothermal strategy as well as subsequent thermal-catalysis treatment. The multi-walled carbon nanotubes encapsulated with magnetic CoNi nanoparticles are immobilized onto core-sheath microrods matrix, constructing effective 1D/1D electron migration bridges and the uniformly dispersed magnetic component to facilitate magnetic coupling effect. Consequently, profiting from the optimized impedance matching, enhanced conduction loss, dielectric polarization, and magnetic loss, the as-prepared sample shows an outstanding absorption capacity with reflection loss value of −56.8 dB and X-band full absorption. When used as electromagnetic shielding materials, the composites exhibit exceptional electromagnetic interference shielding properties. In addition, the upgraded mechanical strength, remarkable voltage-driven Joule heating and superhydrophobic properties endow the absorbers with multi-scenario adaptability and long life-time applications. This work provides well-designed hierarchical structures for high-performance electromagnetic absorbing and shielding with the great prospect of multifunctional applications. The unique three-dimensional hierarchical composites consisting of 1D multi-walled carbon nanotubes anchored on 1D MXene@CF core-sheath microrods are rationally proposed. The prepared composites show excellent electromagnetic wave absorbing and shielding performance, the upgraded mechanical strength, remarkable voltage-driven Joule heating and superhydrophobic properties. [Display omitted] • Hierarchical structures of N-doped carbon nanotubes anchored on 1D core-sheath microrods structure were successfully prepared. • The composites exhibits exceptional electromagnetic wave absorption and shielding properties. • The designed composites show enhanced mechanical strength, excellent voltage-driven Joule heating and superhydrophobic capabilities. [ABSTRACT FROM AUTHOR]

Various carbon nitride (C 3 N 4) materials show great potential as an eco-friendly, visible-light-active photocatalyst for hydrogen evolution reaction (HER). In this work, a new route to produce one-dimensional (1D) P-doped carbon nitride nanotubes is developed via supramolecular self-assembly. The nanotubes are produced by thermal condensation of melamine and cyanuric acid. The addition of an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) improves the uniformity of the nanotubes. It is revealed that the C 3 N 4 nanotubes are formed by thermal condensation of rod-shaped intermediates. The nanotubes show an excellent photocatalytic HER activity under visible light irradiation and are a superior catalyst to 3D C 3 N 4 samples. From thorough structural and photophysical characterizations, it is found that the nanotubes contain larger surface areas, more amine bridges, better crystallinity, and more visible-light-absorption ability than control samples. These structural features are reasons for the enhanced photocatalytic performance. [Display omitted] [ABSTRACT FROM AUTHOR]

The optical transition energies of chiral carbon nanotubes (CNTs) are intimately related to their geometrical structures, and are frequently applied in the recognition and isolation of single nanotubes. Conventional translational crystal lattice (TCL) scheme failed to offer an accurate description of the optical properties of the chiral CNTs due to the formidable unit cell size constraint as well as the complexity of the band structures. Most fitting equations for the Kataura plot, usually based on the empirical correlations with the chiral indices of the CNTs, lack a clear physical interpretation. In this study, we apply the natural helical crystal lattice (NHCL) scheme to systematically analyze the band gap variation of arbitrary chiral CNTs. We derive a global analytical formula that takes into account the comprehensive geometrical connection topologies for the band gap of all (n , m)-CNTs with a diameter larger than 1.2 nm. With the inclusion of the many-body effect, we are able to provide a global Kataura plot prediction with a minimal set of only two fitting parameters, and the results are consistent with the experimental Kataura plot within 0.67% deviation for over 1300 data points. Our formula precisely captures the observed experimental branching features and presents a clear physical rationalization for the topological family effect on the optical excitation energies of chiral CNTs. [Display omitted] [ABSTRACT FROM AUTHOR]

Neutron capture therapy (NCT) is a form of radiotherapy that exploits the potential of some specific isotopes to capture thermal neutrons and subsequently yield high linear energy transfer (LET) particles, suitable for cancer treatment. Recently, relevant technological improvements have been made in terms of accelerators as suitable neutron sources for NCT at hospitals. However, low selective delivery of current drugs to cancer cells remains as the main challenge for successful clinical application of NCT. This work presents an innovative and previously unexplored approach for the design of nanotherapeutic NCT agents. Herein, a new concept based on carbon nanomaterials that seal 6Li active NCT nuclides is investigated. The 6Li active species are located in the inner cavity of the nanocarrier (carbon nanohorns or carbon nanotubes) and therefore, completely protected from the biological environment, avoiding toxicity and degradation. After encapsulation of the active cargo, the external surface of the nanocarrier is modified for improved biocompatibility. The developed 6Li-filled carbon nanohorns offered the possibility to explore 6Li compounds as active NCT agents by delivering therapeutic doses to cancer cells. We envisage that nanoencapsulation of 6Li can trigger the successful development and implementation of Lithium Neutron Cancer Therapy (LiNCT). [Display omitted] [ABSTRACT FROM AUTHOR]

One of the most important characteristics of two-dimensional (2D) electrolytes [1] is their ability to reversibly transform into one-dimensional (1D) structures, such as nanoscrolls. However, when formed, these 1D structures are soft and unstable (because of the weak internal chemical bonds) and poorly electrically conducting (since chemical functionalization introduces a large degree of disorder in the 2D material basal plane). Using PeakForce™ quantitative nano-mechanics (PF-QNM™) mode in atomic force microscopy (AFM) and electrical transport measurements, we demonstrate that a one-step, catalyst-free, graphitization of 1D graphene nanoscrolls leads to an enhanced structural stability (an increase of 6 times in the Young's modulus) and a dramatic reduction of structural disorder (observed by a resulting 5 orders of magnitude reduction of the electrical resistance) These large changes in physical properties open up the doors for the use of 1D graphene nanoscrolls in the study of exotic materials in 1D as well as a plethora of possible industrial applications, such as hydrogen and energy storage, akin to carbon nanotubes but with a much bigger flexibility in terms of morphologies and functionalities. [Display omitted] [ABSTRACT FROM AUTHOR]

Compared with the other absorption materials, multicomponent of CNTs composite materials have become increasingly significant in the preparation of high-performance electromagnetic wave absorption materials due to their unique dielectric-magnetic advantages. In this paper, we use the heating and disintegration of organic amine salt to achieve the restoration of oxides while derivating carbon nanotubes, preparing an excellent performance of Co/Cu/CrN/CNTs composite materials. Due to annealing, slim -shaped CrN evenly attached to the surface of carbon nanotubes. The material forms a rich interface and good impedance matching characteristics, thereby realizing the excellent electromagnetic wave absorption performance of the material. The maximum bandwidth of 7.2 GHz was obtained at 2.62 mm and the minimum reflection loss was – 53.58 dB. The composite material design provides a new way for the development of high-performance electromagnetic wave absorption materials. [Display omitted] • Dicyandiamide derivatives were used to decompose nitriding to achieve the successful synthesis of CrN. • Carbon nanotubes were derived from Co/Cu metal particles as growth sites. • The maximum reflection loss is −53.58 dB and the absorbing bandwidth (<-10 dB) is 7.2 GHz at the same thickness (2.62 mm). [ABSTRACT FROM AUTHOR]

One dimensional carbon nano material has attracted extensive attention in the field of electromagnetic wave (EMW) absorption due to its large aspect ratio, ultrafine nano networks, good thermal stability and designable surfaces. However, one-dimensional nanomaterials are easy to agglomerate, loss and impedance are mismatched, which seriously restricts their application. How to overcome the agglomeration of one-dimensional nanomaterials, as well as design nano-interface and precisely control the dielectric loss are the key to the research of EMW absorbing materials. Inspired by the dense and regular hierarchical structure of pine branches, we use carbon nano fiber (CNF) converted from bacterial cellulose (BC) as the matrix, and in situ growth amorphous carbon nanotubes (CNTs) on its surface, so as to construct a hierarchical architecture similar to pine leaves in nanoscale, which not only solves the common aggregation problem of one dimensional nanomaterial, but also obtains stronger interface polarization capability through hierarchical nano structure. Furthermore, the amorphous CNTs network have moderate conductivity, which does not lead to impedance mismatch. The reflection loss of CNTs/CNF with a CNTs content of 63.2 wt% can reach −68.2 dB at a thickness of 2.7 mm, and the maximum effective absorption bandwidth reaches 5.5 GHz. The design strategy of hierarchical amorphous carbon nanocomposite integrates strong EMW absorption and good impedance characteristics, the synthesized CNTs/CNF composites exhibit excellent EMW absorption properties. [Display omitted] • We synthesized a pine-like branch with controllable CNTs content by in situ growth of well-dispersed CNTs on the nanoscale CNF network. The nano composite takes CNF as the axis, and uniform and dense CNTs are distributed around the axis CNF. • The three-dimensional hierarchical architecture overcomes the problem of easy accumulation of CNTs, enhance interface polarization capability, and enables CNTs to act as a loss medium to more fully attenuate EMW energy. • The in-situ grown amorphous CNT does not damage the impedance characteristics, and forms a three-dimensional conductive network, which is conducive to the migration and transition of electrons and enhances the conductivity loss. [ABSTRACT FROM AUTHOR]

Phosphotungstic acid (PTA) is a highly stable dopant. In this research, transparent conductive films (TCFs) with polyethylene terephthalate as a substrate and PTA/Au secondary p -type doped single-walled carbon nanotubes (SWCNTs) as a conductive layer were prepared by spraying and employed as heating devices. The films had excellent optoelectronic properties (sheet resistance of 46.7 Ω/sq with 87.1% transmittance), mechanical properties (only 0.03 change in sheet resistance after 5000 bending cycles), stability (29.4% change in sheet resistance after one week of exposure to 95% humidity) and electrical heating properties. Transparent flexible heaters (TFHs) made of PTA/Au dual p -type doped SWCNT TCFs have a quick response to temperature changes and outstanding cycling stability. At an operating voltage of 20 V, the temperature of the TFH rapidly reached its maximum steady-state temperature (T max) of ∼120 °C within less than 90 s. After 50 cycles at 15 V in the voltage-on-off cycle test, the T max achieved by the TFH did not change appreciably. The results of the performance evaluation indicate that the film has a bright future in flexible wearable devices for warmth, physiotherapy, or deicing/defrosting applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Polymer-derived pyrolytic carbons (PyCs) are often desirable for low density high-temperature structural applications when they can be reinforced with high stiffness and strength fibers to address brittleness. Nanofibers, such as aligned carbon nanotubes (A-CNTs), can be an ideal reinforcement owing to their high mass-specific properties, and while modeling suggests that properties of A-CNTs at high volume fractions (i.e., 10–30 vol%) could yield significant enhancements, it is unknown how CNT confinement influences processing, as such materials have never been synthesized. Here, we report process development demonstrating the first successful fabrication of fully infused, void-free A-CNT carbon matrix nanocomposites (A/C-NCs) via polymer infiltration pyrolysis (PIP) that establishes a platform to study nanofiber-reinforced polymer-derived ceramics. The size of the average A/C-NC graphitic crystallites increases as CNT vol% increases up to 30 vol%, and the inter-layer separation of the PyC graphitic crystallites decreases, evidencing a nanoscale confinement effect observed in concert with increased mechanical performance. Vickers microhardness testing in the axial CNT direction of A/C-NCs shows agreement with prior data for low vol% CNTs in PyC and mechanical modeling, where specific hardness increases from ∼ 3.3 GPa/(g/cm3) for PyC to ∼ 6.7 GPa/(g/cm3) for 30 vol% A/C-NCs, demonstrating A/C-NCs as an advantaged superhard lightweight material. [Display omitted] • Fabrication of pyrolytic carbon composites with 1-30 vol% aligned carbon nanotubes. • Vacuum- and capillary-assisted infiltration of phenolic resin enable full infusion. • Four polymer infiltration pyrolysis cycles decrease porosity and increases density. • Graphitic crystallites in matrix are longer and denser with nanotube reinforcement. • Specific microhardness increases up to 30 vol% carbon nanotubes, rivaling diamond. [ABSTRACT FROM AUTHOR]

Chirality separation of single-wall carbon nanotubes (SWCNTs) is key to enabling applications in single photon sources, optoelectronic devices and bioimaging, and it generally requires multiple separation steps to obtain single chirality species with the desired purity. In this work, we report the use of a novel sodium hyodeoxycholate (SHC) surfactant for separation of single-chirality SWCNTs. The results demonstrated that chirality-selective adsorption and desorption of SWCNTs on a gel column can be achieved readily by modulating the concentrations of the SHC-based mixed surfactants. Through an optimized one-step procedure, single-chirality (6,5) SWCNTs were successfully separated, and the chirality purity was estimated to be 97% by using a spectroscopic approach, exceeding most reported purities for traditional surfactant-based one- or multiple-step separations. Due to the ultrahigh chirality resolution of the present method, the (6,5) SWCNTs can also be effectively separated from different SWCNT materials with various diameter or chirality distributions, even from materials containing very few (6,5) SWCNTs. The high-purity chirality separation demonstrated in this work lays an important foundation for the industrial production and applications of single-chirality SWCNTs. [Display omitted] [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) structure can improve electromagnetic interference (EMI) shielding effectiveness (SE) of carbon-materials, thereby satisfy the requirement of lightweight. Herein, a leaf-like 3D carbon nanotubes (CNTs)/graphene aerogel film (CGAF) is prepared in which the CNTs are seamlessly embedded in graphene, analogous to veins and mesophyll of a leaf, respectively. The assembly of mesophyll-like graphene into 3D materials not only improves EMI SE, but also changes the EMI shielding mechanism. The addition of veins-like CNTs further amplifies the change of EMI shielding mechanism. The total EMI SE (SE tot) of 3D CGAF is 26.6 dB, which was 3.0 dB and 5.1 dB higher than that of CGP (prepared by compressing CGAF) and GAF (CGAF without CNTs). Besides, the 3D structure makes the absorption SE (SE A) dominates the SE tot of CGAF, accounting for 66.5%, but the reflection SE (SE R) is dominant in the SE tot of CGP and the theoretical SE tot of CGAF. This shows that 3D structure can improve the absorption effect by repeatedly reflecting electromagnetic waves (EMWs) from countless pore walls, and the addition of CNTs further synergizes this effect, thus enhancing the SE tot and SE A. Furthermore, the SE MA (SE tot divided by mass per unit area) of CGAF can reach 12091 dB cm2 g−1, which increases by 12.7% and 18.1% compared to CGP and GAF, respectively. In addition, by combining multilayer CGAF with polydimethylsiloxane (PDMS), the SE tot can reach 74.7 dB at 8.2 GHz, and its SE tot still retains 45.6 dB after 100 cycles of bending, still far above the industry standard (20 dB), showing excellent bending resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

Since the application environment of electromagnetic wave (EMW) absorbing materials is constantly changing, it is of great significance to design it with adjustable performance to adapt to the change of environment. In order to realize the adjustable performance of materials, we use WPU to bond the absorbing monomer CNTs/CNF with a hierarchical structure. After a simple bidirectional freeze-drying method, a resilient CNTs/CNF-WPU layered composite aerogel was prepared. The minimum reflection loss (RL min) of CNTs/CNF-WPU aerogel with 2.5 wt% CNTs/CNF content reaches −77.3 dB and the effective absorbing bandwidth (EAB) can cover the whole X-band. The RL of the sample with a thickness of 4.9 mm can achieve less than −13.4 dB at the full frequency of X-band. The CNTs/CNF-WPU aerogel has a directional arrangement layered structure, which makes it have good stability of EMW absorption performance. It can adhere to at least 100 cycles under 60% strain. Under the condition of applied stress field, with the increase of compressive loading, the distance between the layers becomes narrower, so that the storage charge capacity of the layers increases, the complex permittivity increases, and the EMW absorption performance also changes. By compressing and releasing the block, the EAB of the aerogel can be reversed from low frequency to high frequency. When the compressive loading is 40%, the RL min of the resilient aerogel can reach −54.3 dB at a frequency of 9.7 GHz and a thickness of 4.6 mm, the EAB≥4.2 GHz. It offers an efficient path to explore new smart EMW absorber. [Display omitted] [ABSTRACT FROM AUTHOR]

At present, hydrogen storage by physisorption is being investigated on novel polycrystalline carbon nanotubes (PCNTs) in order to utilize them for large-scale applications. Large-sized nanotubes are susceptible to structural flaws known as polycrystallinity, which evolve owing to the inherent constraints of growth kinetics and purification during the synthesis process. In this study, molecular dynamics simulations (MDS) were used to analyze the adsorption and desorption behavior of PCNTs employing hybrid grand canonical Monte Carlo (GCMC) simulations coupled with microcanonical ensembles. Moreover, a distinctive potential energy distribution technique was used to compute the adsorption metrics. We further investigated the size dependency effects, including curvature, length, and grain boundaries (GBs), on hydrogen adsorption functionalities. The MDS revealed that PCNTs with a moderate grain size of 4 nm are energetically stable and adsorption compatible with maximum gravimetric densities of 8.22 and 1.03 wt% at 77 and 300 K, respectively. Furthermore, the optimized PCNTs were functionalized with Li adatoms of varied concentrations and simulated at various temperatures and pressures. Afterward, adsorption/desorption kinetics and isosteric enthalpies of Li-functionalized PCNTs (Li-PCNTs) were computed to assess the synergistic impacts of Li adatoms and GBs. Li-PCNTs have shown remarkable performance in terms of hydrogen storage and deliverability. Consequently, at 77 and 300 K, Li-PCNTs doped with a 25% adatom concentration exhibited the maximum hydrogen uptake of 10.36 wt% and 2.13 wt%, respectively. Additionally, at 300 and 77 K, the averaged isosteric enthalpy of adsorption, estimated from the adsorption isotherms, was about 7.07 kJ/mol and 4.03 kJ/mol, respectively. Therefore, despite their ability to prevent metal clustering, PCNTs have a modest impact on adsorption metrics. Our findings open up new avenues for the utilization of PCNTs in large-scale hydrogen storage applications with suitable functionalization strategies. [Display omitted] • The hydrogen adsorption metrics of Li-doped polycrystalline CNTs (PCNTs) were studied using MD simulations. • A novel potential energy distribution technique was incorporated with MD simulations. • Binding energy convergence analysis was performed to obtain the optimum size of polycrystalline CNTs. • Moderate-grain-sized polycrystalline CNTs showed favorable hydrogen adsorption and energetic stability. • The Li-concentration between 15 and 20% is best suited for H 2 adsorption/desorption abilities of polycrystalline CNTs. [ABSTRACT FROM AUTHOR]

The effectiveness of mechanical enhancement of carbon nanotubes-polymer matrices, particularly, epoxy resin (EP), depends strongly on the interface interaction between constituents. Providing rough surface and chemical activity of CNTs is the effective way to reach that. To explore both approaches, in this study, unzipped CNTs (uCNTs) and drilled CNTs (dCNTs)were prepared by Hummers methods and chemical etching. The structure of uCNTs and dCNTs were characterized by FT-IR, TG and XPS. The Eu3+ complexes were anchored to CNTs, uCNTs, and dCNTs via strong interaction to form a stable "tenon" structure. That materials were found useful to fabricate the composite with EP. Our study reveals that the ultimate tensile and flexural strengths of Eu-dCNTs/EP increases by 161% and 226%, indicating that Eu-dCNTs improves significantly the mechanical properties of EP. The drilling treatment and the "tenon" structure of the Eu-dCNTs hybrid play a key role in improving the mechanical properties of EP. Fracture morphology and the strengthening mechanism were discussed. Our study shows an effectiveness of using dCNTs and uCNTs to fabricate luminescent polymer composites with enhanced properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Owing to their remarkable properties and ordered architecture, vertically aligned CNT forests (VACNT) hold promises for countless applications ranging from energy storage to multifunctional fiber production. Over the last three decades, studies of carbon nanotube (CNT) growth have provided invaluable insight into the CNT nucleation and growth mechanism and enabled critical advancements in nanotechnology. Nevertheless, the ability to fully harness the exceptional VACNT properties in commercial devices is bottlenecked by compatibility of current CNT synthesis processes with large-scale manufacturing. Metal foil substrates present an economic alternative to traditional insulating substrates, like silicon or quartz, and are compatible with both roll-to-roll and automated, large-scale, batch processes. Compared to CNT growth on Si substrates, metal foils present additional challenges, such as increased roughness and reactivity at high temperatures. Nonetheless, many successful VACNT growths on conducting metal foils have been reported, which demonstrate the feasibility of metal substrate use for large-volume production of high-quality CNTs. In this review, we discuss advancements in the field of VACNT growth on metal foil and specifically examine different choices for metal substrates, barrier and catalyst layers, deposition and growth methods, resulting CNT characteristics, and highlight a number of applications that benefit from CNT growth on metal substrates and transition to large-scale manufacturing. [Display omitted] • Exceptional VACNT properties are transformative for many technologies. • Challenges and successes of growing VACNTs on metal foils are described in detail. • Material choice, process conditions, and resulting CNT characteristics are reviewed. • Fundamental investigations and application driven developments are highlighted. • Products based on VACNTs grown on metal supports are at the market horizon. [ABSTRACT FROM AUTHOR]

Recently, we proposed a new strategy to develop a three-dimensional conductive network within a cement mortar by coating sand with graphene. In such a design, the interfacial transition zone (ITZ) was directly embedded in the conductive network, thus resulting in high piezoresistive performance. Considering that the ITZ between coarse aggregate and paste is typically much more vulnerable than that of the ITZ between fine aggregate and paste, here we extend this strategy to concrete, whose piezoresistive property has been rarely reported yet intimately relevant for practical application. Conductive fine and coarse aggregates are readily prepared by dipping coating with carbon nanotube (CNT) polymer slurry. Because of the high volume percentage of aggregates (∼70%) in concrete, the obtained concrete exhibit very high conductivity at low CNT usage of 0.41% (by weight of cement), several orders of magnitude higher than that reported before at similar CNT load. We find that the mixture incorporating conductive aggregates has a 28-day electrical resistivity of 1076 Ω cm with a compressive strength loss of 17.8%. On this basis, we further optimize the high-conductivity concrete by connecting conductive aggregates with a small amount of 0.25 wt% carbon fibre, which demonstrates an outstanding 28-day electrical resistivity of 235 Ω cm and an excellent fractional change in resistivity of ∼80%, more than one order of magnitude higher than those obtained in comparable systems. The experimental results also testify that our smart concrete exhibits acceptable mechanical properties and durability. The simple operation and low-cost benefits make our smart concrete demonstrate great potential for large-scale practical application. [Display omitted] [ABSTRACT FROM AUTHOR]

Taking full advantage of interface engineering to strengthen interface polarization is an effective strategy to improve microwave absorption. Therefore, constructing the mixed-dimensional heterostructures and/or three-dimensional (3D) interconnected network structures should be attractive pathways to create the abundant interfaces for enhanced interfacial effect. Herein, mixed-dimensional framework structure carbon foam (CF)/carbon nanotubes (CNTs)@Fe 3 C@Fe 3 O 4 samples consisting of 3D CF, one-dimensional (1D) CNTs and zero-dimensional (0D) Fe 3 C@Fe 3 O 4 nanoparticles were elaborately designed and produced through a simple catalytic chemical vapor deposition process. The as-prepared CF/CNTs@Fe 3 C@Fe 3 O 4 heterostructures with the different contents of CNTs could be selectively produced by regulating the pyrolysis time. Owing to the unique structure and excellent synergistic effects, the obtained mixed-dimensional CF/CNTs@Fe 3 C@Fe 3 O 4 samples presented the excellent comprehensive electromagnetic wave absorption performances (EMWAPs) including strong absorption capabilities, broad absorption bandwidths, thin matching thicknesses and low densities. Furthermore, the obtained results demonstrated that the enhanced content of CNTs greatly boosted their conduction and polarization loss abilities, which resulted in the enhanced comprehensive EMWAPs. Therefore, our findings not only offered a simple strategy to produce the mixed-dimensional framework structure magnetic CF/CNTs-based heterostructures as excellent lightweight high-efficiency microwave absorbers, but also provided an effective pathway to make the best of interface engineering for enhancing interface polarization. Constructing mixed-dimensional lightweight flexible CF/CNTs@Fe 3 C@Fe 3 O 4 heterostructures: an effective strategy to achieve tunable and boosted microwave absorption. [Display omitted] • Mixed-dimensional framework structure CF/CNTs@Fe 3 C@Fe 3 O 4 heterostructures were produced through a simple process. • The CF/CNTs@Fe 3 C@Fe 3 O 4 with different contents of CNTs were produced by regulating the pyrolysis time. • The enhanced content of CNTs greatly boosted their conduction and polarization loss abilities. • Owing to the abundant interfaces, the designed CF/CNTs@Fe 3 C@Fe 3 O 4 presented the excellent EMWAPs. • Our findings provided an effective pathway to make the best of interface engineering for enhanced interface polarization. [ABSTRACT FROM AUTHOR]

Bolometric photodetectors based on single-wall carbon nanotubes (SWCNTs) have shown advantages of an ultrawide absorption spectrum, high charge carrier mobility, good processability, and high mechanical flexibility. However, their detection performance needs to be improved to meet the requirements of real applications. A flexible infrared photodetector was fabricated based on high quality SWCNT films. The device showed an ultrahigh detectivity up to 1.35 × 108 Jones under a bias voltage of 0.2 V, and a short response time of 70 ms in air. In addition, we found that the photocurrent response of the detector was closely related to the structure of the SWCNT network. A negative photocurrent was measured using photodetectors constructed from highly-crystalline SWCNTs owing to dominant phonon scattering transfer, while a positive photocurrent was detected from those fabricated using defect-rich SWCNTs due to dominant electron hopping transfer. Our results shed light on the construction of high-performance SWCNT film-based infrared photodetectors. A high negative photocurrent was measured using photodetectors constructed from highly-crystalline SWCNTs (I G /I D ∼177) owing to dominant phonon scattering transfer, while a positive photocurrent was detected from those fabricated using defect-rich SWCNTs (I G /I D ∼31) due to dominant electron hopping transfer. [Display omitted] [ABSTRACT FROM AUTHOR]

Electromagnetic interference (EMI) generated by electronic devices is disruptive to surrounding electronic components and deemed harmful to human beings. As high-speed, miniaturized mobile devices become ubiquitous, developing lightweight, thin, and flexible electromagnetic shielding materials (ESMs) to replace the common metallic ones is of utmost importance. Here we report the development of a high-efficiency standalone ESM made of a self-standing CNT mat (CNTM). This textile is electrically conductive (∼50 × 103 S m−1) and can be post-treated by chemical oxidation or thin copper metalization, increasing the conductivity by ∼10 and ∼1000 times, respectively. CNTMs were tested for shielding effectiveness (SE) in an ultra-wide bandwidth of 30 kHz–70 GHz. Maximal SE of >120 dB was measured for a 30 g m−2 CNTM (<100 μm thickness) at 70 GHz. SE normalized by thickness (SE/t) reached a value of >20,000 dB cm−1 for an HCl-oxidized CNTM. Both SE values are the highest values for non-metal-based ESMs. The CNTMs' experimental EMI shielding behavior corresponds to Schelkunoff's theory which confirms that the CNTM SE is dominated by conductivity-dependent reflection at lower frequencies (<1 GHz) and thickness-dependent absorption at higher frequencies. CNTMs (20 g m−2) were utilized as EMI gaskets and in composite EMI enclosures, tested at 10–50 GHz and 50 MHz-90 GHz, respectively. EMI CNT gaskets reached an SE of 120.9 dB at 50 GHz, surpassing the performance of high-end commercial gaskets (600 g m−2). EMI composite boxes laminated with CNTMs reached an SE of 119.9 dB at 90 GHz, outperforming the non-CNT laminated reference. [Display omitted] • Direct-spun CNT mats were tested as thin, lightweight EMI shielding materials. • Tests were conducted in an ultra-wide bandwidth of 30 kHz–70 GHz. • 30 g m−1 CNT mats showed extraordinary EMI shielding efficiency of up to 121.7 dB. • A good fit to Schelkunoffs theory verified CNT mats act as non-magnetic conductors. • CNT mats were successfully integrated as EMI gaskets and in EMI boxes. [ABSTRACT FROM AUTHOR]

Carbon nanotubes/Carbon nanofibers (CNT/CNF), owing to their abundant active sites and high acidic resistance, have emerged as promising electrocatalysts for high-energy-density vanadium redox flow batteries (VRFB). However, the utilization of CNT/CNF has been obstructed owing to problems such as cost, and the detachment of CNT/CNF from the carbon electrode caused by the flowing electrolyte in VRFB. In this study, we proposed a novel strategy for uniformly implanted multiwall CNT in electrode materials such as graphite felt, for the development of efficient electron-networked electrodes. The weed root-like morphology of the electrode improved the charge transfer ability and minimized the increase in overpotential even after 1000 cycles of stability test. As a result, the electrode exhibited a high discharge capacity of 30.7 Ah·L−1 and an energy efficiency of 86.9%. Therefore, the proposed CNT implanted electrode can be used as an alternative design in practically feasible VRFB exhibiting sustainable electrochemical performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Field-effect transistor (FET) biosensor has received widespread attention due to their unique high-sensitivity properties. In conventional FET biosensors, the complicated interaction between the sample solution and the semiconductor channel always results in poor stability. Especially for FET-based pH sensors, the interface failure caused by the harsh acid-base working environment makes accurate, continuous, and low hysteresis pH measurement quite challenging. Here, we report a carbon nanotube (CNT)-FET pH sensor with enhanced environmental stability by introducing HfO 2 film into the gate insulator. The proposed devices show desired immunity to environmental interference including various chemical and physical factors. More importantly, we verified the feasibility of this CNT-FET device for continuous pH sensing, which demonstrates a sensitivity of 67.62 mV/pH, a wide pH range of 1.34–12.68, and low hysteresis of 500 pA with pH switching loops of 4.22–10.24. This work not only realizes a high-performance pH sensor but also paves the way for the development of FET biosensors with high environmental stability, which is of great significance for FET biosensors to maintain normal working performance in complex systems. [Display omitted] • A floating gate CNT-FET biosensor with high environmental stability was fabricated and demonstrated as a high-precision pH sensor. • Excellent pH sensing capabilities were achieved, including a pH range of 1.34–12.68, sensitivity near the Nernst limit. • Based on the stable HfO 2 -solution interface, the desired hysteresis, and repeatability of this pH sensor were achieved. [ABSTRACT FROM AUTHOR]

We report the existence of moiré patterns and magic angle physics in all families of chiral collapsed carbon nanotubes. A detailed study of the electronic structure of all types of chiral nanotubes, previously collapsed via molecular dynamics, has been performed. We find that each family possesses a unique geometry and moiré disposition, as well as a characteristic number of flat bands. Remarkably, all kinds of nanotubes behave the same with respect to magic angle tuning, showing a monotonic behavior that gives rise to magic angles in full agreement with those of twisted bilayer graphene. Therefore, magic angle behavior is universally found in chiral collapsed nanotubes with a small chiral angle, giving rise to moiré patterns. Our approach comprises first-principles and semi-empirical calculations of the band structure, density of states and spatial distribution of the localized states signaled by flat bands. [Display omitted] [ABSTRACT FROM AUTHOR]

Efforts to fabricate high-conducting and high-strength free-standing graphene/carbon nanotube (CNT) buckypaper through room-temperature functionalization have been frustrated by the defective surface of the graphene and CNTs. In this study, high-quality graphene sheets were prepared via an amino-assisted liquid phase exfoliation method and used to integrate with CNTs to form free-standing flexible graphene/CNTs buckypaper. After that, individual graphene and CNT of the graphene/CNTs buckypaper were linked via diazonium chemistry to generate covalent bonds. By tuning functionalization time, the functionalized graphene/CNTs buckypaper exhibits an electrical conductivity of 87,500 S/m and a Young's modulus of 22.3 GPa, which are 6 and 10 times higher, respectively, than unfunctionalized graphene/CNTs buckypaper. Density functional theory calculations demonstrate that charge transfer rate (K et) of the aryl linker bonded moiety configuration via covalent functionalization is an order faster than without the aryl linker bonded moiety configuration. Unprecedently, the capacitance of the functionalized graphene/CNTs buckypaper is 359.6 mF/cm3 at a scan rate of 1 mV/s with no capacitance change after 10,000 cycles of testing. This work sheds the light of the value of molecular engineering in the design of novel composite for flexible electronics, energy storage and provides important insights into the understanding of basic principles of covalent functionalization of graphene/CNTs. The functionalized graphene/CNTs buckypaper were crosslinked to form covalent bonds between individual material via diazonium chemistry reaction and it achieved an electrical conductivity of 875 S/cm and Young's modulus of 22.3 GPa, which are 6 and 10 times higher than unfunctionalized graphene/CNTs buckypaper. Besides, charge transfer rate (K et) of the functionalized graphene/CNTs shows ten times faster than unfunctionalized moiety configuration. [Display omitted] [ABSTRACT FROM AUTHOR]

The great attention of rechargeable Zn-air battery has motivated extensive research on the development of inexpensive, highly efficient, and robust noble-metal-free bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a supramolecular complex derived strategy was used to prepare bamboo-like carbon nanotubes with abundant Fe single atoms and sub-nanometer clusters anchored on tube walls. When served as a bifunctional ORR/OER electrocatalyst, this hybrid showed a small overpotential gap of 0.713 V and excellent stability. More importantly, a large power density of 213 mW cm−2 and stable long-time round-trip charge-discharge performance were achieved for the assembled rechargeable Zn-air batteries. Density functional theory calculations revealed that atomic Fe–N 4 moiety in the catalyst could be the essence of high ORR activity, while atomic Fe–N 4 moiety coupled sub-nanometer cluster significantly reduces the OER energy barrier. This work provides an effective strategy for the preparation of high-performance and robust oxygen electrode catalysts as well as a significant new insight on the catalytic mechanisms, helping to realize significant advances in energy devices. A supramolecular complex derived strategy was used to synthesize a tubular Fe–N/C material enriched with atomically dispersed Fe–N 4 moiety to boost the oxygen reduction activity and atomic Fe–N 4 moiety coupled sub-nanometer cluster to improve the oxygen evolution activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to their ultra-high thermal conductivity, carbon nanotubes (CNTs) have become a hot spot for thermal enhancement materials. However, many researchers have found that the CNT assemblies had a reduced thermal conductivity by 2–3 orders of magnitude even though that of an individual CNT was 3700 W m − 1 K − 1. From a nanoscale perspective, interfacial phonon scattering is widely accepted as the culprit for above-mentioned enormous reduction of thermal transport. This paper reviews the thermal transport mechanisms and their enhancement approaches using the modification of micro- and nano-scale guest materials. Various aspects like the individual-level to batch-level modulations of CNTs, the phonon transport law, the thermal enhancement effect and the different interface optimization mechanisms are summarized. The bonding force is the best way to improve the interfacial thermal transport, and the excellent spatial arrangement design of CNTs can greatly enhance the directional thermal transport. In addition, a multi-material structural synergy to break through the limitation of weak phonon transport under the van der Waals force is also discussed. [Display omitted] • Effects of structure, arrangement and interface on the inter-tube thermal transport. • Influence of overlapping length, crossing angle and interaction on heat transfer. • Synergistic effect of inter-tube junctions on the thermal conduction of the network. • Open phonon channels by guest materials to enhance the cross-tube thermal transport. [ABSTRACT FROM AUTHOR]

Silica (SiO 2) is regarded as a promising anode for lithium-ion batteries due to the high specific capacity, abundant resources and low cost. However, the inherently poor electrical conductivity and the huge volume variation during charge/discharge process significantly hinder the application of SiO 2. Designing nanostructured SiO 2 and coating with high conductivity materials are effective methods to solve the above challenges. In this work, advanced SiO 2 anodes were prepared by coating hollow SiO 2 nanotubes (SNTs) with lignin or phenolated and depolymerized lignin furfural resin (PDLF)-derived carbon. The novel structure of the obtained SNTs greatly promotes the rapid transport for both Li+ and electron, increases the exposed active sites for Li+ insertion and accommodates the volume change of SNTs. Especially, PDLF possesses abundant functional groups, high carbon content and thermosetting property, which are beneficial to the dispersion of SNTs and formation of a cross-linked 3D conductive network. Thereby, SNTs@C-PDLF presents higher specific capacity of 661 mAh g−1 at 100 mA g−1, superior rate capability (262 mAh g−1 at 3000 mA g−1) and better cycling stability (549 mAh g−1 at 1000 mA g−1 after 800 cycles) compared with SNTs@C-lignin and pristine SNTs. Silica (SiO 2) is considered to be one of the most promising anode materials due to its high theoretical specific capacity (1965 mAh g−1), abundant resources and low cost. However, SiO 2 also faces problems such as large volume change and poor conductivity, resulting in poor rate capability and limited cycle life. In this work, we designed advanced SiO 2 anodes by coating hollow SiO 2 nanotubes (SNTs) with lignin-/phenolated and depolymerized lignin furfural resin (PDLF)-derived carbon. The SNTs@C-PDLF anode delivers a high discharge capacity of 911 mAh g−1 after 300 cycles. This work sheds light on the developing high-performance SiO 2 anode and will promote the value added transformation and utilization of biomass. [Display omitted] • High-capacity SiO 2 anode was prepared by coating SiO 2 nanotubes with biomass-derived carbon. • The hollow and porous structure of SiO 2 nanotubes effectively accommodate the volume change during lithiation/delithiation. • Biomass-derived porous carbon enhances the electrical conductivity and shortens Li+ diffusion distance. [ABSTRACT FROM AUTHOR]

Precise design of oxygen electrode catalysts can alleviate the problems of slow kinetic reaction and high overpotential in the rechargeable zinc-air flow batteries (ZAFBs). Herein, an ideal 3D carbon-based material for FeCo alloy inlaid to Fe/Co and N co-doped bamboo-like carbon nanotubes (CNTs) is prepared by means of a one-pot high-temperature pyrolysis strategy of three metal organic frameworks (MOFs) mixed-precursors. The concentration of active metal species, the amount of conductive CNTs and the hierarchical porous structure with high specific surface area in this material are regulated. The optimal catalyst, Fe/12Zn/Co-NCNTs, demonstrates excellent electrochemical activity with a high half-wave potential of 0.879 V for oxygen reduction reaction (ORR) and low overpotential of 340 mV at 10 mA cm−2 for oxygen evolution reaction (OER) in the half-cell. Moreover, the smaller bifunctional ΔE value of Fe/12Zn/Co-NCNTs and Fe/(12Zn/Co)-NCNTs catalyst are 0.693 V and 0.717 V, respectively, less than the commercial Pt/C+IrO 2 (ΔE = 0.77 V). The ZAFB yields a high open circuit voltage of 1.518 V, peak power density of 166 mW cm−2, and specific capacity of 809.1 mAh g−1 when employing Fe/12Zn/Co-NCNTs as air cathode because of the synergistic effect that improves both OER and ORR. More importantly, both Fe/12Zn/Co-NCNTs and Fe/(12Zn/Co)-NCNTs as the bifunctional catalysts produce a low charge-discharge voltage gap and high cycle lifespan of more than 320 h at 10 mA cm−2. This work provides a facile strategy for fabricating high-efficiency and low-cost bifunctional electrocatalysts for ZAFBs and other clean energy applications. [Display omitted] • A hybrid-pyrolysis synthetic method enabled the properties of MOFs to be improved. • As-prepared material possesses Fe/Co-N x and FeCo alloy active sites and 3D nanoporous structure. • Fe/12Zn/Co-NCNs exhibits highest half-wave potential for ORR and lowest overpotential for OER. • Fe/12Zn/Co-NCNs presents smaller bifunctional ΔE and longer ZAFB cycle lifetime. [ABSTRACT FROM AUTHOR]

For carbon-based nanocomposites, enhanced conduction loss, polarization loss and impedance match are beneficial for enhancing electromagnetic wave (EMW) absorption property. In this work, graphene nanoribbon (GNR) nanocomposite foam system with regulated atomic defects, enhanced interfacial polarization and suitable impedance match were combined to achieve high-efficient EMW absorption: (1) Tubular carbon nanotube (CNT) is unzipped via chemical oxidation to obtain GNR with unique structure of long strip; (2) Oxidation and reduction of GNR enables the regulation of in-plane atomic defects; (3) a suitable electrical conduction of GNR renders its nanocomposite a better impedance match than CNT or graphene nanoplatelet (GNP) nanocomposites; (4) cellular structure in GNR nanocomposite further improves the impedance match compared with air; (5) the long-strip characteristic of GNR features the high-efficient interfacial polarization even in cell walls which undergo stretching, while tubular CNTs have weak interfacial polarization and platelet GNPs have deteriorated interfacial polarization after cell wall stretching. Owing to the above specific tailored multiscale electron dissipation strategy, GNR nanocomposite presents better EMW absorption property of −42.6 dB than CNT nanocomposite of −21.8 dB and GNP nanocomposite of −25.6 dB. Furthermore, supercritical carbon dioxide (scCO 2) foaming improves the impedance match and enhances GNR interfacial polarization. The EMW absorption property of GNR nanocomposite foam further increased to −54.1 dB after selectively and restrictively locating GNR in cell walls. [Display omitted] • Tubular CNT is unzipped via chemical oxidation to obtain long strip GNR. • Thermal and chemical reduction are used to regulate in-plane defects of GNR. • Cellular structure in GNR nanocomposite further improves the impedance match. • Synergistic effect between ribbon and thin cell wall to boost interface polarization. [ABSTRACT FROM AUTHOR]

Poly(triarylamine) (PTAA)-wrapped single-walled carbon nanotubes (SWCNTs) functioned in a dual role as an efficient hole-transporting layer and electrode in perovskite solar cells (PSCs). Thanks to the well-matched energy level, increased hole-transporting mobility, and hydrophobicity rendered by dopant-free PTAA, this dual-role SWCNTs electrode applied-PSCs using dopant-free PTAA achieved a better efficiency and stability than reference standards using LiTFSI-doped Spiro-OMeTAD. This dopant-free PTAA-applied SWCNTs electrode is expected to not only give a solution for efficiently using the SWCNTs electrode in PSCs, but also unveil the mechanism of the interaction between the hole-transporting layer and SWCNTs. [Display omitted] [ABSTRACT FROM AUTHOR]

Obtaining high-density horizontal single-walled carbon nanotube (SWNT) arrays is the key point of developing SWNT-based integrated circuits. However, some catalysts showing good control over SWNT structures possess relatively low activity to grow SWNT, which restricts the density of the grown arrays. Therefore, we developed a rational method to grow high-density SWNT arrays by iron (Fe)-assisted pre-cracking of carbon source in gas phase. A tiny amount of Fe, decomposed from ferrocene, was introduced into the chemical vapor deposition system with the gas flow without forming Fe nanoparticles on the substrates. The density of the SWNT arrays grown from Mo 2 C, WC and Cu catalysts can be significantly increased by 3–5 times with the help of Fe, reaching 40, 35 and 24 tubes μm−1, respectively. Through gas chromatography and Raman spectrum characterization, it is proved that carbon source decomposed more completely with Fe in the gas phase, which resulted in higher utilization efficiency of carbon source and better quality of the grown SWNTs. This pre-cracking approach is an effective way to improve the density of SWNT arrays with controlled structures. [Display omitted] [ABSTRACT FROM AUTHOR]

Pressure sensors based on field-effect transistor mechanism has received a lot of attention from researchers, which can effectively suppress low contrast and crosstalk effects. In this paper, we demonstrate a pressure sensor based on carbon nanotube field-effect transistor (CNTs-FET) and three-dimensional conformal force-sensitive top electrode with high sensitivity and easy integration. The high mobility field-effect transistor sensors were prepared using CNTs films with 99.9999% semiconductor concentration as the channel material. Conformal graphene nanowalls (GNWs) film on pyramidal micro-structure arrays worked as force-sensitive top electrode, the field-effect transistor sensor shows a sensitivity of 946.23 kPa−1 and 43.79 kPa−1 in the linear range of 0–30 Pa and 0.03–10 kPa, much higher than piezoresistive sensor (the sensitivity of about 377.73 kPa−1) and capacitive sensor (the sensitivity of 115.78 kPa−1). And the sensitivity and range of the sensor can be adjusted by the force-sensitive layer orientation design. Additionally, the sensor's response time is less than 30 ms, the recovery time is about 30 ms. The field-effect pressure sensor could detect ultra-low pressure (about 1.3 mg) of the chrysanthemum petals, and also could record the dynamic crawling process of the insect. [Display omitted] [ABSTRACT FROM AUTHOR]

Stimuli-responsive membrane reactors offer advanced strategies towards simultaneous separation and degradation of persistent organic contaminants, allowing for triggered response through photo or electro stimuli. However, the scalable fabrication of stimuli-responsive nanoporous membranes with high selectivity and catalytic reactivity is still challenging in practical application. Here, photo-electro responsive membranes were designed by assembling carbon nanotubes (CNT) scaffolds decorated with conformal nanoscale SnO 2 coatings. The membranes, built from spinnable CNT materials supported the generation of a unique class of ultrathin and flexible ultrafiltration membranes with thicknesses down to 25 nm and pore size as narrow as ∼20 nm. The CNTs were used as effective conductive photosensitizers to promote charge transfer from the graphitic to the SnO 2 layer, supporting synergistic effects arising from generated Schottky-like diodes to improve the photo/electro-catalytic activity of nanocomposite membranes. The SnO 2 -CNT membranes exhibited high water permeance of 2.24 × 103 L m−2 h−1.bar−1, and faster reaction kinetics of 77.6 × 10−3 for acetaminophen degradation, which was 2–10 times higher than the kinetics achieved by currently available catalytic membrane reactors. The structural stability and outstanding performance of SnO 2 -CNT membranes were maintained over 8 reuse cycles with ∼99% degradation efficiency against acetaminophen in 60 min. The unique solid-state fabrication method of uniformly coated catalytic metal oxide on well aligned CNTs provides a scalable feasible approach to produce high-performance ultrafiltration photo/electro-catalytic membrane reactors towards cost-effective water purification at a competent reaction rate. [Display omitted] • Schottky-like SnO 2 -CNT membranes are developed via solid-state CNT spinning and SnO 2 atomic layer deposition. • Stimuli-responsive SnO 2 -CNT ultrafiltration membranes exhibit fine-tuned pore size down to 20 nm. • Synergistic photo/electro-catalytic performance is boosted via generated SnO 2 -CNT Schottky barriers. • A feasible approach to engineer high performance CNT-based catalytic membrane reactors. • High water permeance and fast reaction kinetics are achieved during photo/electro-catalytic ultrafiltration of acetaminophen. [ABSTRACT FROM AUTHOR]

Sorting single-chirality enantiomers is the ultimate goal for single-wall carbon nanotube (SWCNT) separation. In this work, aqueous two-phase extraction (ATPE) is used to obtain highly purified (>80%) left- and right-handed (6,5) SWCNTs with limited experimental steps. The optimized surfactant conditions are presented, and analytical ultracentrifugation (AUC) and near-infrared photoluminescence (PL) measurements are used to examine the surfactant wrapping and partition coefficient change conditions (PCCCs) required for separation. Our study provides valuable insights into the underlying mechanisms behind surfactant-assisted SWCNT separations and facilitates the use of SWCNT enantiomers in fundamental studies and applications in the future. [Display omitted] • Single-wall carbon nanotube enantiomers are prepared using a simple aqueous two-phase extraction method. • Different co-surfactant systems are examined to optimize the separation results. • Surfactant wrapping on both right- and left-handed (6,5) SWCNTs are investigated by analytical ultracentrifugation. • The partition coefficient change conditions are measured for handedness sorting. [ABSTRACT FROM AUTHOR]

This study investigates a novel approach of improving the mechanical performance of scarf-repaired carbon fiber reinforced composites by integrating nanomaterials in the patch constituents. Two distinct types of carbon-based nanomaterials, thermally exfoliated graphene oxide grade-2 (TEGO) and Epocyl™ 128–06 (MWCNT) are integrated into the patch resin matrix and fiber/matrix interface in an upscaled manner. Another group of composites are repaired with pristine patches in accordance with the existing and prevalent composite repair method. Compared to the reference panel, 109.9%, 99.7% and 99.3% stiffness recoveries are achieved for the patches with CNT and TEGO-incorporated resin matrices and TEGO-electrosprayed fibers, respectively. Location-wise analyses of the test data show that the stiffness, strength, Poisson's ratio, and strain values depend on the number of patch plies in each specimen. Fractographic inspections show that the failure sites shift towards the outer areas of the scarf region demonstrating an enhanced stress redistribution due to the nanomaterials. SEM observations show that nanoparticles affect toughening mechanisms based on the type, location, and alignment of the nano-reinforcement, which in turn limits the shear-dominated failures (SDF) in the baseline and pristine patch repair system. In CNT- and TEGO-reinforced resin patches, efficient crack bridging and fracture plane tilting/twisting or crack bifurcations are observed whereas the electrosprayed TEGO particles positioned at the perimeter of fibers operate as a shield for the fibers to prevent SDFs. These findings demonstrate that failure behavior of repair systems and therefore their mechanical performance are governed by the type of nano-reinforcement and its integration process. [Display omitted] • Nano-integrated patches restore stiffness and strength, and prevent patch loss. • Carbon nanotubes dispersed in the patch matrix enhance the interfacial adhesion. • Randomly oriented graphene oxide flakes in the matrix hinder shear dominated failure. • Electrosprayed graphene oxide shields the tows, protecting them from transverse cracks. [ABSTRACT FROM AUTHOR]

Multifunctional nanocomposite strain sensors, especially those that contain dispersed multiwall carbon nanotubes (MWCNTs), are known to possess exceptional electrical conductivity. These nano-reinforced composites can be used for structural health monitoring. It is with this in mind that we focus our attention on calibrating the electromechanical behaviour of MWCNT-reinforced epoxy nanocomposites both numerically and experimentally. In particular, our main objective is to unravel the coupled electromechanical behaviour of the conducting composite prior to failure. In the numerical effort, we adopted the effective-medium homogenization and Mori-Tanaka method to account for tunnelling resistance and to predict the sensory capability of the newly developed composite. In the experimental effort, a conductive epoxy nanocomposite containing high quality MWCNTs randomly dispersed within liquid neat epoxy system was developed. The conducting domains of the developed nanocomposite were characterized using atomic force microscope (AFM) measurements. Electromechanical characterisation of the MWCNT-reinforced nanocomposites was also performed using controlled uniaxial tensile tests to evaluate its sensory capability against load. The results of our work reveal: (i) excellent agreement with the micromechanical model, and (ii) the dramatic influence of the concentration of the MWCNTs, their agglomeration and aggregation on the sensory sensitivity of the MWCNT-reinforced epoxy nanocomposite. Interestingly, an increase in the MWCNT filler loading led to a decrease in the sensory sensitivity of the nanocomposite as measured by uniaxial strain gauge factor. The work was further extended to highlight the sources of errors that could lead to erroneous results in developing and calibrating electrically conducting pathways in polymer nanocomposites. [Display omitted] [ABSTRACT FROM AUTHOR]

Transition metal carbide/nitride (MXene) materials have triggered intensive research interest in the field of microwave absorption (MA). However, the complicated fabrication process and monotonous loss mechanism of MXene materials seriously hinder their practical applications. Here, we first developed a green and facile synthesis of dielectric-magnetic MXene-Fe nanocomposites via one-step Lewis acidic molten salts etching, which were combined with carbon nanotube (CNT) filler and silicone rubber (SR) matrix to fabricate double-layered MXene-Fe/CNT/SR composites by casting and curing. The in-situ growth magnetic Fe nanoparticles on MXene and unique double-layered structure composed of MXene-Fe/SR as the upper absorption layer and CNT/SR as the bottom reflection layer imparted the composites with excellent MA properties by offering appropriate impedance matching, strengthened internal reflection, polarization, magnetic loss, and conductive loss. Accordingly, the proposed double-layered composites showed superior MA properties compared with other MXene-based composites. The MXene-Fe-45%/CNT-5%/SR sample showed a reflection loss value of −65.9 dB at 12 GHz and an effective absorption bandwidth up to 8.24 GHz at 2.86 mm thickness. The double-layered composites exhibited tunable absorption frequency between the whole Ku-band and X-band by simply regulating the sample thicknesses and filler contents. These features indicate that the developed double-layered MXene-Fe/CNT/SR composites have great potential for high-performance MA applications. This study offers a novel and simple strategy to develop high-efficiency and broadband MA materials. [Display omitted] • Dielectric-magnetic MXene-Fe nanocomposites were developed by a facile and green one-step method. • The appropriate impedance matching and enriched loss mechanism contributed to the enhanced microwave absorption properties. • The double-layered composite exhibited superior microwave absorption properties with RL min of −65.9 dB and EAB of 8.24 GHz. • Tunable absorption frequency between the whole K-band and X-band was achieved. [ABSTRACT FROM AUTHOR]

The rational design of N‒doped multi‒walled carbon nanotubes (MWCNT) by surface engineering was performed by changing the synthetic method, the nitrogen source, and the addition of a surface defect promoter. The solvothermal (S), and the thermal treatment (TT) were used employing melamine or urea as nitrogen precursors. It was found that the activity for ORR through the TT increased in contrast to pure MWCNT and MWCNT modified by the S method. In addition, melamine allowed to obtain better activity than urea as N precursor. However, as the activity of N‒doped MWCNT was not as close to Pt/C, hydrogen peroxide as a surface‒defect promoter was added before the TT. The material obtained using melamine, the TT method, and H 2 O 2 was employed as a highly active material for ORR, presenting onset (E o) and half‒wave (E 1/2) potentials of 0.9 and 0.77 V vs. reversible hydrogen electrode (RHE) respectively, having an activity loss of only 17% after 24 h. In the Zn‒air battery (ZAB), a cell voltage of 1.30 V was achieved, displaying a power density of 101 mW cm−2 and a specific capacity of 650 mA h g−1, being this capacity near to that obtained using Pt/C. Finally, Density Functional Theory allowed to explain how the incorporation of engineering defects and heteroatoms allowed to create a free energy state that increase the electrocatalytic activity. [Display omitted] • Highly active N-doped MWCNT were obtained by analyzing the effect of different variables. • The presence of topological defects modulates the MWCNT electronic character. • The overpotential for the N-doped MWCNT was only 70 mV higher in comparison to benchmarked Pt/C. • Cell voltage of 1.30 V and a power density of 101 mW cm−2 were achieved by the N-doped MWCNT. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWNT) is desirable next generation semiconductor for flexible, transparent and even stretchable with exceptional electrical characteristics. Here, high-performance n-type semiconducting SWNT field-effect transistors (s-SWNT-FETs) are achieved by chemical doping using anion-π interaction between SWNT and anion of tetrabutylammonium fluoride (TBAF) salt. The Fermi level (E F) of SWNT shifts to the conduction band edge with increasing dopant concentration. The doped s-SWNT-FETs exhibit significant improvement in electron mobility (39.4 cm2V−1s−1) with high current on/off ratio (>104) compared to those of un-doped device. The doping using anion–π interaction leads to populate electron density of channel and reduces both channel and contact resistance by 99.0% and 99.6%. Excess carriers introduced by the doping compensate traps by shifting the E F toward conduction band edge. The doped device showed improved current stability after 10 h of bias stress test, while the current of undoped FET decreased by 40.4%. Finally, flexible FETs with TBAF doped s-SWNT network are demonstrated on polyethylene naphthalate substrate and show stable operation after 2000 times bending test. [Display omitted] [ABSTRACT FROM AUTHOR]

High temperature anneal is of importance to create nanocarbon-based materials with excellent functions and performances. However, a comprehensive understanding on annealed nanocarbon assembly structures has been challenging. We successfully propose the micro and macroscopic structural analysis of 0.8–3.4 nm diameter few-walled carbon nanotube (CNT) bundled network by a multifaceted characterization, which were annealed over 1200–3000 °C in the form of a film as the case study. Up to 1800 °C carbonaceous impurities were removed to secure nanospace among nanotubes, i.e. interstitial channels important to design multiple functions. Beyond 1900 °C nanoscale graphitic particles were generated on the nanotube bundles, then grown to be micro-meter scale toward 3000 °C. Parallel to the particle growth, small diameter (<1.2 nm) nanotubes became undetected at 2200–2400 °C with a decrease in available interstitial channels, finally resulting in the nontubular, graphitized network structures at 2600–3000 °C. The anneal at 1200–1800 °C can afford the high purity CNT bundled network structures, and the higher temperature anneal led to the high crystallinity graphitized network structures. To understand the structural evolution, 14 different analytical methods were employed, and two-dimensional correlation analysis from the collected data revealed the synchronous and asynchronous structural parameters with the annealing temperature. Thus, we found that the structural changes occurred in 3 stages of 1200–1800 °C, 1900–2400 °C, and 2600–3000 °C. On the other hand, the electrical conductivity gradually decreased due to the removed carbonaceous impurities and the structure changes. Our findings can be an asset for carbon material science and pave a way toward nanocarbon applications with the films, fibers, and composites. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel in situ self-catalyzed synthetic strategy is explored to prepare graphitic carbon nanotubes (CNTs) wrapped and amorphous nanocarbon shells coated LiFePO 4 microclews (LiFePO 4 @C@CNT) at one-step. The formation mechanism of CNTs entangled LiFePO 4 @C microclews is investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the in situ intergrowths of CNTs and LiFePO 4 @C could be realized by the catalytic effect of Fe 3 C nanoparticles based on the tip-growth mechanism. The as-prepared LiFePO 4 @C@CNT-5 composite with a low carbon content of 5 wt %, an optimum composition of graphitic CNTs and amorphous carbon shells (I D / I G = 0.9), a specific surface area of 83 m2 g−1 and an electronic/ionic conductivity of 0.68 S cm−1/2.1 × 10−12 cm2 s−1 delivers a stable discharge capacity of 158.2 mAh g−1 at 0.1 C, outstanding rate capability of 136.1 mAh g−1 at 1 C and remarkable long-term cycling stability of 129.6 mAh g−1 after 1000 cycles at 1 C, indicating a promising application in high-power lithium-ion batteries. The combined good electronic-ionic conductivity of twisted carbon nanotubes and porous nanocarbon shells and robust mechanical stability of geometrically confined LiFePO 4 particles within dual nanocarbon matrices contribute to the excellent electrochemical performance of LiFePO 4 @C@CNT. [Display omitted] [ABSTRACT FROM AUTHOR]

Recently, interest in Li-metal batteries (LMBs) has been revived because the high specific capacity and lowest operating potential of Li-metal anodes help in resolving the existing issues of conventional Li-ion batteries. Unfortunately, the main problems associated with poor coulombic efficiency and dendritic Li formation impede the use of Li-metal anodes for commercial batteries. Among various strategies to address these intrinsic challenges of Li-metal anodes, the approach to utilize 3D current collectors has shown attractive results in terms of electrochemical stability. Herein, we assessed two different carbon nanotubes (e.g., double-walled nanotubes (DWNTs) and multi-walled nanotubes (MWNTs) scaffolds to study how the structure of carbon-based current collectors affects the coulombic efficiency and electrochemical stability of LMBs. As MWNTs have a more favorable structure for the reversible storage/release of Li-ion than DWNTs, they facilitate uniform and stable Li deposition over the entire surface of the MWNT matrix, thereby diminishing the growth of sharp dendritic Li. This resulting effect directly contributes to the stable operation of Li-metal cells at high current densities. Moreover, it has shown a remarkable improvement in electrochemical stability when the MWNT current collector was applied to the anode-free cell using a LiCoO 2 cathode. The MWNT/LiCoO 2 cell exhibited excellent cycle retention (97% at 50 cycles) with a high coulombic efficiency (99%). This work suggests that the material of the current collectors plays an apparently important role in the electrochemical stability of LMBs. [Display omitted] • CNT scaffolds were used as 3D current collectors for Li-metal batteries (LMBs). • Double-walled nanotubes (DWNTs) and multi-walled nanotubes (MWNTs) were employed. • MWNT current collectors enabled more uniform Li deposition than DWNT current collectors. • Half- and full-cells with the MWNT current collector exhibited excellent performances. [ABSTRACT FROM AUTHOR]

Measuring electronic Raman scattering (ERS) has become an efficient method for structural characterization of metallic single-wall carbon nanotubes (SWCNT). However, applying this method to other types of SWCNT-based structures, e.g. , those with strong van der Waals (VDW) coupling, is currently not well studied. In this work, we combine electron diffraction, Rayleigh and Raman spectroscopies to investigate the ERS process near 36 metallic transitions in 21 individual double-wall carbon nanotubes (DWCNTs) with all types of electronic configurations. We observe the partial suppression of ERS intensity in DWCNTs compared to SWCNTs and mainly attribute it to the effect of dielectric screening of Coulomb interactions. We probe ultra-pure macroscopic multi-chirality DWCNT solutions and identify the role of inhomogeneous broadening in observing ERS peaks in Raman spectra. Based on the experimental findings, we propose an adapted method for the structural identification of DWCNT samples from the ERS data. The obtained results can be generalized to the characterization of the emerging 1D VDW heterostructures based on metallic SWCNTs. [Display omitted] [ABSTRACT FROM AUTHOR]

Self-sensing refers to a structural material sensing itself. It is valuable for smart structures. It is mainly achieved by measuring the electrical resistance of the structural material, as the resistance is affected by strain and damage. Electrical-resistance-based strain/damage self-sensing in cement-based materials emerged in 1993 and the field has grown greatly since then. This is a critical review of this field. Elastic strain causes reversible resistivity change. Damage causes irreversible resistivity increase. Conductive admixtures are required. For short carbon fiber as admixture, the resistivity decreases upon compression, due to the fiber-matrix interfacial resistivity decrease, and increases upon tension; upon flexure, the compression surface resistance decreases and tension surface resistance increases. As shown by the gage factor, carbon fiber/nanofiber/nanotube is more effective than carbon-black/graphite-nanoplatelet/graphene, and short carbon fiber is more effective than carbon nanotube. The addition of carbon nanotube to short carbon fiber decreases the gage factor. For nanotube/nanofiber, the resistivity decreases upon compression, due to increased contact among the nanotube/nanofiber units. The sensing performance is best when the admixture volume fraction is near the percolation threshold. Silica fume and surfactants in the cement mix promote the admixture dispersion. Sonication for promoting the nanocarbon dispersion is not necessary for the fiber dispersion. Nanofiber/nanotube deposition on fine aggregate enhances the dispersion. Macroscale steel fibers are less effective than microscale ones, which are less effective than carbon fiber. Common experimental method pitfalls are also addressed. The four-probe method is much more reliable than the two-probe method. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, we propose novel, highly effective Pt-free counter electrode (CE) material for dye-sensitized solar cells (DSSC) based on the hierarchical carbon nanofibers/carbon nanotubes/NiCo (eCNF/CNT/NiCoNP) ternary nanocomposites. The materials were obtained by combining the electrospinning technique and CCVD synthesis of carbon nanotubes directly on the surface of eCNF. By using various conditions of the CNT growth, it was possible to obtain series of nanocomposites differing with their morphology, surface chemistry, and structural ordering. The conducted studies unraveled significant correlations between the disordering of the nanocomposites, and their electrocatalytic activity towards reduction of I 3 −. The investigation methods included i.a. SEM, TEM, XPS, UPS, EDS, XRD, SAED, CV, EIS and J-V characterizations. The counter electrodes based on the nanocomposite synthetized at the lowest CCVD temperature of 700 °C exhibited remarkable catalytical activity as evidenced by very low charge transfer resistance of 0.93 Ω cm2. Based on the obtained data, we propose new, alternative interpretation of the additional minor arc appearing at the high-frequency region of EIS Nyquist spectra of carbon based-CE. The DSSC with eCNF/CNT/NiCoNP-electrodes were characterized by efficiencies up to 7.08% (avg. η = 6.95%), which was higher than for Pt-based devices (avg. η = 6.80%), thus demonstrating excellent performance of prepared CE. Our results confirm that the eCNF/CNT/NiCoNP nanocomposite material is a promising low-cost CE alternative for DSSC. [Display omitted] • High catalytic activity of hierarchical carbon nanofibers/NiCoNP in I 3 −/I− redox. • Defects in CNT were majorly responsible for the enhanced activity of nanocomposites. • Temperature of CCVD controlled electrochemical performance of nanocomposites. • Minor hi-freq. EIS arc seems to originate from charge transfer at FTO/particle IF. • Hierarchical carbon nanocomposites are promising Pt-free counter electrode for DSSC. [ABSTRACT FROM AUTHOR]

Uniform 1D/2D amorphous carbon nanostructures were discovered to spontaneously form on the fracture surfaces of carbon nanotube-concentrated ceramic composites upon their static fracture. The factors potentially responsible for the formation, thickness and detectability of such nanosized amorphous carbon structures are discussed. Ultimately, a mechanism for their formation upon fracture is proposed. The present discovery could help to avoid misinterpretation of the carbon/matrix interfacial strength, reactions and the composites reinforcing mechanism especially in carbon-concentrated composite systems. Furthermore, this is the first report on the formation of amorphous carbon nanostructures upon fracture of a carbon-based composite material. [Display omitted] [ABSTRACT FROM AUTHOR]

As the key to manufacturing large scale integrated circuits, horizontally aligned semiconducting single-walled carbon nanotube (s-SWNT) arrays play a key role in the next-generation electronic device. Though various techniques have been developed, obtaining pure s-SWNT horizontal arrays is still the greatest challenge. Here, we propose an effective and facile method to produce s-SWNT arrays from a diverse perspective by implementing photochemical chlorination on the as-grown aligned SWNT arrays. The electrical measurements demonstrate a high fraction of s-SWNTs (>98.1%) after photochlorination, and its exceptional performance as a field-effect transistor with an on-off ratio up to 3730. Meanwhile, through the well-controlled mask-assisted photochlorination, a type of metallic-semiconducting SWNT intramolecular junction with rectifying diode and non-linear transport characteristics has also been successfully obtain. Our work provides a new method for the preparation of high-purity s-SWNT arrays and SWNT intramolecular junction, which has great significance for the carbon-based nano-electronic devices in applications. [Display omitted] • Transition from m-SWNT to s-SWNT. • Selective modification to s-SWNT. • Less damage and contamination to the samples. • Convenient and simple. • Area-selected method to fabricate SWNT intramolecular junction. [ABSTRACT FROM AUTHOR]