Properties Of Nanotubes Research Articles

Multifiller carbon nanotube, graphene, and carbon black composite filaments: A path to versatile electromaterials

Abstract Addressing the growing demand for conductive and flexible composites, this research focuses on producing thermoplastic composite fibers made of polyurethane and carbon nanomaterials featuring the highest possible electrical conductivity. Based on a recently developed methodology enabling the formation of very high filler contents of 40% w/w, this work presents a systematic investigation of the role of all the materials used during the manufacturing process and selects the materials that ensure the best electrical performance. The results show that the highest electrical conductivity and current-carrying capacities are obtained when dimethylformamide is used as a solvent, and small amounts of AKM surfactant aid the de-agglomeration of carbon nanomaterials. It is also shown that the hybridization of MWCNTs filler with graphene nanoplatelets and small amounts of carbon black is beneficial for the electrical properties. However, the highest performance is achieved with SWCNTs as fillers, exhibiting two orders of magnitude higher electrical conductivities of 6.17 × 104 S/m. Impact statement The article presents a pioneering exploration into the synthesis and application of a novel composite material. This research significantly impacts the field of electromaterials by introducing a cutting-edge approach that leverages the synergistic properties of carbon nanotubes, graphene, and carbon black within a single filament. The impact of this research extends beyond the laboratory, influencing the development of next-generation materials that bridge the gap between conventional materials and advanced nanomaterials. The presented composite filaments open avenues for the creation of innovative devices and systems that demand good mechanical strength, electrical conductivity, and thermal stability. Moreover, the versatility of these filaments allows for the optimization of materials properties, enabling customization based on specific application requirements. In addition to its technological significance, the paper contributes to sustainability efforts by facilitating the production of lightweight, energy-efficient materials. The insights provided by this research have the potential to reshape the landscape of materials science, inspiring further exploration and innovation in the quest for versatile and high-performance electromaterials. Graphical abstract

"Surface-Like Growth" Strategy for the Direct Synthesis of Horizontally Aligned Boron Nitride Nanotubes.

The inherent properties of boron nitride nanotubes (BNNTs) can be further enhanced through the control of their anisotropy. In particular, horizontally aligned BNNTs (HABNNTs) exhibit considerable potential for various applications. However, directly synthesizing HABNNTs is difficult owing to the random floating of BNNTs and the absence of directional forces. Here, we employed a simple, efficient, and universal "surface-like growth" strategy to synthesize high-density and high-quality HABNNTs in the W2B5/Zn precursor system. First, the floating range of BNNTs was restricted to the vicinity of the precursor, and then, directional forces were applied to induce BNNT directional growth along the substrate surface. Experiments and simulations confirmed that the HABNNT orientation could be controlled through manipulation of the directional forces. Furthermore, the strategy was employed for HABNNTs synthesis using the MoB2/Zn, further demonstrating the universality of the approach. Overall, this work offers a fresh perspective on the synthesis of HABNNTs, further expanding their potential applications.

Novel synthesis of thermoresponsive single-walled carbon nanotubes/poly(N-isopropylacrylamide) hybrids

Poly(N-isopropylacrylamide) (PNIPAM) is one of the most well studied thermoresponsive polymers and its microgels undergo a reversible volume phase transition (VPT) at temperatures close to that of the human body. Coupling this property with the unique optical properties of single-walled carbon nanotubes (SWCNT) in the near infrared (NIR) leads to interesting nanohybrids that could be used as multi-responsive sensors/actuators for biological applications.We show the synthesis of thermoresponsive SWCNT/PNIPAM hybrids using two different non-covalent strategies, preserving the nanotube optical properties such as fluorescence. The first strategy involves the dispersion of the SWCNT in water with sodium dodecyl sulfate (SDS), and subsequent in situ synthesis of PNIPAM microgels inside the SDS coatings around the nanotubes. The second strategy starts with modifying the nanotubes with a pyrene derivative, which in turn is used as the starting point for the in situ polymerization of the PNIPAM microgels, thus ensuring that the polymer grows around the nanotubes. In both cases, we obtain hybrids showing a phase transition at temperatures close to that of the human body, with the absorption and fluorescence spectra of the hybrids in the NIR changing in response to the changing dielectric environment. These systems could be used as actuators/sensors in biological systems.

Carbon nanotubes as a basis of metamaterials and nanostructures: Crafting via design optimization

Nanotruss structures made of carbon nanotubes are investigated in two conceptual applications: either as building blocks of metamaterials or for nanostructural applications. The nanotrusses are optimized for different purposes, including various loadings, boundary conditions, parameterizations, objectives and constraints used to formulate optimization problems. The procedure relies on a recently developed framework consisting of molecular dynamics simulations, neural networks and finite elements. This framework is now used in the design optimization of nanostructures and the performances of different popular heuristic optimization methods are compared. Five applications of nanotrusses made of carbon nanotubes are analyzed in detail to investigate the mechanical behavior of such structures and the efficiency of the optimizations. Besides an introductory example, the design of an energy trapping carbon nanotube nanotruss, an auxetic nanotruss, a cantilever nanotruss and the maximization of the compressive strength of a metamaterial are presented. It is shown that the exceptional mechanical properties of carbon nanotubes can indeed be exploited for the development of structures and materials with extraordinary mechanical properties. Although hampered by material and geometrical nonlinearity of the problem, most of the tested optimization methods have proven to be a good choice for the design of such materials and structures.

Energy-efficient design of quaternary logic gates and arithmetic circuits using hybrid CNTFET-RRAM technology

Multi-valued logic (MVL) extends binary logic by providing a framework to represent complex systems with more than two truth values. MVL was introduced to confront the enormous interconnect issue associated with the binary logic in implementing the presnt day complex nanoelectronic architectures. This paper delves into the circuit design, computational aspects, and practical applications of the quaternary logic system, which is a type of MVL with four truth values. The multi-threshold property of carbon nanotube field-effect-transistors (CNTFETs), combined with the ability of resistive random-access memory (RRAM) to store multiple resistance values, has enabled the design of quaternary logic gates and arithmetic circuits. A new CNTFET-based design architecture has been proposed to implement the quaternary logic compatible with the existing technologies. Quaternary logic gates such as inverter, NAND, and NOR, and quaternary arithmetic circuits including decoder, half adder, and multiplier have been designed. The power-delay-product (PDP) of the proposed quaternary inverter, NAND, NOR, half adder, and multiplier is 62.38%, 93.4%, 80.29%, 14.79%, and 20% less than the least PDP of the quaternary designs under consideration. The static power reduction due to the effecciency of the design architecture and high OFF state resistance offered by integrating RRAM into the logic design was explored.The proposed circuits have been subject to various types of parameter variations to validate thir proper functionality in presence of these variations.

Water at the nanoscale: From filling or dewetting hydrophobic pores and carbon nanotubes to "sliding" on graphene.

In this work, we study the effect of nanoconfinement on the hydration properties of model hydrophobic pores and carbon nanotubes, determining their wetting propensity and the conditions for geometrically induced dehydration. By employing a recently introduced water structural index, we aim at two main goals: (1) to accurately quantify the local hydrophobicity and predict the drying transitions in such systems, and (2) to provide a molecular rationalization of the wetting process. In this sense, we will further discuss the number and strength of the interactions required by the water molecules to promote wetting. In the case of graphene-like surfaces, an explanation for their unexpectedly significant hydrophilicity will also be provided. On the one hand, the structural index will show that the net attraction to the dense carbon network that a water molecule experiences through several simultaneous weak interactions is sufficient to give rise to hydrophilic behavior. On the other hand, we will show that an additional effect is also at play: the hydrating water molecule is retained on the surface by a smooth exchange of such simultaneous weak interactions, as if "sliding" on graphene.

Organic solar cell efficiency improvement through architecture engineering by integrating carbon nanoring – SCAPS 1D modelling

This research work aims to investigate on improving the performance of organic solar cells (OSC) by proposing new architectures that progressively integrate carbon nanotubes. This contribution takes into account the exceptional properties of carbon nanotubes (CNT) highlighted in recent work, with the aim of addressing the current challenges of materials used in the manufacture of conventional OSCs, such as reactivity with the ambient medium, stability over time, better transport of charge carriers, etc. Using a reference OSC cell with the following structure: PEDOT/BHJ/PDINO and the numerical one-dimensional simulation tool SCAPS, which helps in validating the modelling approach, we gradually replace each layer with a CNT-based material exhibiting superior properties. In this respect, we carry out calculations on the different cells architectures, to better visualize energy-level alignment profiles, the different current-voltage (J-V), and quantum efficiency (QE) characteristics. Approaches toward efficiency improvement were discussed, by investigating the effects of active layer thickness, the doping level, the charge carriers mobility, defect density, and external parameters such as temperature. After numerous calculations and modelling, very promising results were finally achieved with a full CNT-based solar structure with the following recorded performances: VOC=0.87V, JSC=27.81mA/cm2, FF=80.91%, and PCE=19.63%. These results are the first theoretical report for a complete CNT-based modelled OSC and, given the reliability and robustness of the approach adopted, they can be considered as relevant for future theoretical and experimental work. The integration of CNT as functional layers is a remarkable step forward in OSC architectures engineering for efficiency enhancement. CNT are good candidates for light harvesting applications.

Fabrication of a salivary amylase electrochemical sensor based on surface confined MWCNTs/β-cyclodextrin/starch architect for dental caries in clinical samples

Salivary α-amylase (α-ALS) has drawn attention as a possible bioindicator for dental caries. Herein, combining the synergistic properties of multi-walled carbon nanotubes (MWCNTs), β-cyclodextrin (β-CD) and starch, an electrochemical sensor is constructed employing ferrocene (FCN) as an electrochemical indicator to oversee the progression of the enzymatic catalysis of α-ALS. The method involves a two-step chemical reaction sequence on a screen-printed carbon electrode (SPCE). X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscope (FE-SEM), and Dynamic light scattering (DLS) were used to characterize the synthesized material, while Static water Contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were performed to monitor each step of sensor fabrication. The electrochemical sensor permitted to detect α-ALS within the linear range of 0.5–280 U mL−1, revealing detection (LOD), and quantification (LOQ) values of 0.041 U mL−1, and 0.159 U mL−1, respectively. Remarkably, the sensor demonstrated exceptional specificity and selectivity, effectively discriminating against other interfering substances in saliva. Validation of the method involved analyzing α-ALS levels in artificial saliva with an accuracy range of 97 % to 103 %, as well as in real clinical saliva samples across various age groups.

Investigating the optical properties and electronic structure of gallium phosphide nanotubes doped with arsenic via implementing first-principles calculations.

This study investigates the impact of arsenic doping on the optical characteristics and electronic structure of zigzag (8, 0) and armchair (4, 4) gallium phosphide nanotubes using first-principles calculations based on the GaP1-xAsx system, where x = 0, 0.25, 0.5, 0.75, and 1. The electronic calculations showed that doping more arsenic atoms reduces the energy band gap for zigzag and armchair GaPAs nanotubes. PDOS analysis indicates that Ga-4p and P-3p orbitals play a significant role in determining the electronic properties of the GaP nanotube. The dominance of Ga-4p and P-3p orbitals in both the valence and conduction bands indicates their importance across the energy spectrum of the material. The complex dielectric function and absorption coefficient of zigzag and armchair GaP1-xAsx nanotubes are calculated for incident radiation with energies ranging from 1 to 6.2eV. Optical results revealed that both zigzag and armchair GaPNTs exhibit strong absorption in the UV-visible regions due to electronic transitions between different Van Hove singularities. Also, due to quantum confinement effects, pure zigzag gallium phosphide nanotube exhibited two absorption edges at wavelengths (273 and 375nm). These edges stand from the energy level's quantization in the nanotube construction, affecting the absorption characteristics. Substitutional doping by arsenic atoms changes the absorption edge to the long wavelengths due to decreased bandgap energy. Investigating electronic structures and optical properties of nanotubes proposes several advantages, such as understanding the doping effects on the nanotube structure and contributing to the direction of the experimental studies. These computational studies play a key role in developing the applications of nanomaterials. Calculations of density functional theory (DFT) are achieved via the SIESTA package. SIESTA is a powerful and effective tool for executing DFT calculations on a large system of atoms. It generates numerous output files covering detailed information about the electronic structure, optical properties, total energy, optimized geometry, and other computed properties. The generalized gradient approximation GGA with Perdew-Burke-Ernzerhof PBE functional was used. A vacuum region of 10 A0 was applied to avoid the interactions of adjacent nanotubes.

A First-Principles Study on the Anchoring Properties of Defective Single-Walled Carbon Nanotubes for Lithium-Sulfur Batteries

The application of lithium-sulfur (Li–S) batteries is impeded by the significant polysulfide shuttling phenomenon. Developing suitable anchoring material is an effective way to restrain this behavior. In this work, the anchoring performance of lithium polysulfide (LiPSs) on defective single-wall carbon nanotubes (DSWNT) is investigated by density functional theory. The results demonstrate that the DSWNT with three carbon vacancies (DSWNT-3) has the highest forming capacity and the strongest adsorption capacity, indicating it has the best anchoring effect of LiPSs. As the anchoring material of the cathode, DSWNT-3 has greater energy than solvent molecules to inhibit the dissolution of long-chain polysulfides. In general, DSWNT-3 demonstrates notable efficacy as an anchoring material for Li–S batteries, which establishes a theoretical foundation for exploring the anchoring characteristics of defects and their application in the cathode of Li–S batteries.

Study of the Effect of Growth Temperature on the Properties of Nitrogen-Doped Carbon Nanotubes for Designing Nanopiezotronic Devices

Study of the Effect of Growth Temperature on the Properties of Nitrogen-Doped Carbon Nanotubes for Designing Nanopiezotronic Devices

A density functional theory study on the photocatalytic performance of PtS2 nanotubes with high carrier mobility for photocatalytic water splitting

In this paper, the electronic and photocatalytic properties of PtS2 nanotubes have been further investigated by means of first-principles approach. We observed that the band gap of PtS2 nanotubes increases with the increase of the radius, while the strain energy decreases with the increase of the radius. Significantly, the electron mobility of PtS2 nanotubes was 1.34 × 103cm2V-1S-1, while the hole mobility was only 15.95 cm2V-1S-1. The band edge positions of PtS2 nanotubes at pH=0 can satisfy the requirement of the water splitting redox potential. Moreover, the band gap is decreased by strain regulation which should expand the light absorption range. Based on these important findings, we expect that PtS2 nanotubes will have great potential in photocatalytic material applications.

Tensile properties at various strain rates of flexible carbon nanotube film densified by the combination of chlorosulfuric acid and uniaxial drawing

AbstractThe quasi‐static tensile properties of carbon nanotube (CNT) films have been extensively investigated, yet research on their impact tensile properties at high strain rates remains scarce. In this article, CNT films prepared by floating catalyst chemical vapor deposition (FCCVD) method were densely arranged by chlorosulfuric acid (CSA) under wet stretching. The Instron 3365 and miniaturized split Hopkinson tension bar (SHTB) were used to conduct tensile testing at different strain rates. The findings reveal that CSA wet‐stretching markedly enhances the density and orientation of CNT films, resulting in significant improvements in tensile properties with a notable strain rate effect. Specifically, when immersed for 60 s under a draft ratio of 40% and a strain rate of 1900 s−1, the densified CNT films exhibit maximum stress and energy absorption values of 777.44 MPa and 54.79 MJ/m3, respectively, achieving a 637.1% and 425.7% increase compared with the original film. This research provides a convenient and feasible strategy to prepare CNT films with high energy absorption tolerance across various strain rates, thus expanding the practical application potential of CNT films.Highlights The study innovates a posttreatment way to produce superior FCCVD CNT films. CSA treatment and wet stretching enhance CNT films' mechanical properties. Dynamic fracture strength boosts over 600% and energy absorption raises over 400%. CSA can purify FCCVD‐prepared CNT films, greatly improving their properties. The Prep can be effectively integrated with the direct spinning process.

Mechanical properties of carbon nanotube (CNT) reinforced polymers using electron‐deficient aromatics as additives

AbstractIn initial experiments the effects of aromatic model substances on carbon nanotube (CNT) dispersions in dimethylformamide (DMF) were investigated. Electron‐deficient aromatics interact strongly with CNTs, causing increased agglomeration and sedimentation. Conversely, electron‐donating aromatics stabilize CNT dispersions in DMF. Polymers with electron‐deficient aromatics, such as polydinitrostyrene (PDNS), exhibit a concentration‐dependent effect: low concentrations lead to stabilization of dispersions, while higher concentrations lead to sedimentation. This suggests that such polymers can enhance attraction between the matrix of CNT‐reinforced polymers as well as stabilize the dispersed CNTs. Polycarbonate, modified with polydinitrocarbonate (PDNC) and reinforced with CNTs showed improved mechanical properties. The addition of 6 wt.% CNTs and 6 wt.% PDNC resulted in a notable improvement with a 22% increase in tensile strength, a 29% increase in flexural strength, a 39% increase in Young's modulus and a 47% increase in flexural modulus. This enhancement resulted in an overall mechanical performance comparable to the high‐performance polymer polyetherimide. However, there must be noted, that the addition of PDNC increases the CNT particle size, which can negatively affect mechanical properties. The results highlight the additive's dual role in enhancing adhesive interactions while potentially increasing CNT agglomerate sizes.Highlights Interactions of CNTs dispersed in DMF and various aromatics were investigated. Polydinitrocarbonate (PDNC) was synthesized as a new additive for CNT‐composites. Polycarbonate/CNT‐composites were obtained using extrusion. Test specimens with CNT contents up to 6 wt.% were obtained. Mechanical properties of polycarbonate reached the level of polyetherimide.

Exploring the thermal and mechanical properties of PAI-Graphene monolayers and nanotubes: Insights from molecular dynamics simulations

Two-dimensional (2D) materials are widely applicable in emerging technologies, with graphene remaining a focal point of interest. Among the computationally designed 2D carbon allotropes is PAI-Graphene (PAI-G), formed through the lateral polymerization of molecules containing 5- and 6-membered rings, specifically Polimerized as-Indacene. This study employs reactive molecular dynamics simulations to explore the thermal and mechanical properties of PAI-G monolayers and nanotubes using the AIREBO-M potential. The results reveal that the melting point of PAI-G is 3200 K, significantly lower than that of graphene. Anisotropic behavior in elastic properties is observed in PAI-G monolayers, with similar trends seen in nanotubes of varying chiralities. The Young’s modulus values for these systems range between 650 and 900 GPa. Furthermore, the analysis of nanotubes across different diameters unveils a correlation between diameter and elastic constants. A Machine Learning Interatomic Potential (MLIP) was trained to confirm the appropriateness of the standard parameterized AIREBO-M potential for describing the thermomechanical behavior of PAI-G.

Studies, characterizations and evaluation of the antibacterial activity of Silver Titanate Nanotubes

Titanium nanostructures have been widely studied due to their potential for various applications. One of its most promising applications is in the antibacterial activity, in particular, of Silver Titanate Nanoubes (Ag-TiNT). The determining factors for the high efficiency process against bacteria are related to the surface area of the material and the main metal that composes it. Microbial infections continue to be one of the most serious complications in different areas, particularly in the hospital environment. This work was investigated as bactericidal properties of Silver Titanate nanotubes against Gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa and Gram-positive bacteria of Staphylococcus aureus, in systems containing only the Ag-TiNT for the antibiotic compounds. In addition, the study of the main, vibrational and morphological characteristics of Ag-TiNT was carried out. As a result, as microdilution plates accompanying only the positive anti-bacterial dish, while in the microdilution plates containing Ag-TiNT with antibiotics, divergent results. Abstract: Ag-TiNT morphology structures, electron microscopy (SEM, TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and dispersion spectroscopy were detected of X-ray energy (EDS).

Effect of vacancy defect on the structural and electrical properties of single-walled silicon nanotube

The effect of vacancy defects on zigzag and armchair single-walled silicon nanotubes (SiNTs) has been investigated using the self-consistent charge density functional tight-binding (SCC-DFTB) method. The findings indicate that the introduction of defects leads to the inability of the smaller-diameter tube to uphold its tubular structure and cluster. Conversely, the larger-diameter tube undergoes an elliptical transformation, yet retains tubular characteristics and hexagonal structures displaying specific symmetry. The double vacancy defect alters the atomic arrangement on the side opposite the defect. The stability of single-walled SiNTs is related to defect type and chiral index. In addition, the single vacancy defect increases the binding energy and stability of the zigzag tube, while causing a rapid decrease in stability of the armchair tube (7,7). The spin polarization phenomenon manifests within the defect tube, resulting in the splitting of the initial degenerate energy band and a significant decrease in its degeneracy. The existence of electronic interaction, results in a prominent manifestation of vacancy-induced magnetism in armchair and zigzag defect tubes. This phenomenon gives rise to localized spin-up bands situated below the Fermi level, as well as localized spin-down bands positioned above the Fermi level. In the energy band structure of most nanotubes, there are conduction bands or valence bands passing through the Fermi level, leading to a transition from semiconductor to semimetal or metal properties.

Wet-spinning of carbon nanotube fibers: dispersion, processing and properties

ABSTRACT Owing to the intrinsic excellent mechanical, electrical, and thermal properties of carbon nanotubes (CNTs), carbon nanotube fibers (CNTFs) have been expected to become promising candidates for the next-generation of high-performance fibers. They have received considerable interest for cutting-edge applications, such as ultra-light electric wire, aerospace craft, military equipment, and space elevators. Wet-spinning is a broadly utilized commercial technique for high-performance fiber manufacturing. Thus, compared with array spinning from drawable CNTs vertical array and direct dry spinning from floating catalyst chemical vapor deposition (FCCVD), the wet-spinning technique is considered to be a promising strategy to realize the production of CNTFs on a large scale. In this tutorial review, we begin with a summative description of CNTFs wet-spinning process. Then, we discuss the high-concentration CNTs wet-spinning dope preparation strategies and corresponding non-covalent adsorption/charge transfer mechanisms. The filament solidification during the coagulation process is another critical procedure for determining the configurations and properties for derived CNTFs. Next, we discuss post-treatment, including continuous drafting and thermal annealing, to further optimize the CNTs orientation and compact configuration. Finally, we summarize the physical property-structure relationship to give insights for further performance promotion in order to satisfy the prerequisite for detailed application. Insights into propelling high-performance CNTFs production from lab-scale to industry-scale are proposed, in anticipation of this novel fiber having an impact on our lives in the near future.

Carbon nanotubes-encapsulated Co/Co7Fe3 nanocomposites: Achieving wideband electromagnetic wave absorption at ultrathin-thickness by regulating magnetic phase ratio

Nowadays, through various strategies such as composition regulation and structural design, the electromagnetic wave (EMW) attenuation ability of composites has been significantly improved. Nevertheless, at ultra-thin sample matching thicknesses, it is still a challenge for absorbing materials to possess high-intensity and wide bandwidth simultaneously. In this work, the cobalt/iron nitrilotriacetic acid chelates (Co/Fe-NAC) were fabricated by a one-step hydrothermal self-assembly strategy. Then, a series of carbon nanotubes-encapsulated Co/Co7Fe3 (Co/Co7Fe3@CNTs) nanocomposites were constructed by coating glucose hydrothermal carbon on Co/Fe-NAC precursors and subsequent calcination process. By controlling the Co/Fe ion content, the magnetic phase ratio in the product can be efficiently regulated to comprehensively optimize microwave absorption (MA) performance. The minimum reflection loss (RL) of the optimized sample is −42.6 dB at only 1.1 mm thickness, and the effective absorption bandwidth (EAB) reaches up to 10.1 GHz (7.9–18 GHz). Surprisingly, for all samples, the widest EAB can exceed 8.2 GHz at the ultra-thin thickness (thinner than 1.3 mm) and the strongest RL values are all below −30 dB (99.9 % EMW can be absorbed). Such excellent MA performance is attributed to the strong magnetic loss of highly dispersed magnetic nanoparticles, the strong dielectric properties of carbon nanotubes and shells, optimized impedance matching, as well as the synergistic effect of multi-dimensional heterogeneous components and structures. Moreover, the high-frequency structure simulator (HFSS) was used to further analyze the multi-polarization behaviors and heterogeneous magnetic coupling effect. This work may provide a new direction to the fabrication of efficient and ultra-thin absorbers, and Co/Co7Fe3@CNTs nanocomposites may become a promising candidate for practical application in the MA field.

A review of structural and electronic properties of graphyne-based nanotubes

A review of structural and electronic properties of graphyne-based nanotubes