Carbon Nanotube Core Research Articles

Hierarchical Nanowire Host Material for High‐Areal‐Capacity All‐Solid‐State S/SeS2 Batteries

AbstractAll‐solid‐state sulfur batteries (ASBs) suffer from electrical and ionic conduction problems due to the insulating sulfur. By comparing three host materials with different structural characteristics, herein, carbon nanotubes (CNTs) decorated with a conductive metal sulfide (CoMoS2@CNT) is demonstrated, designed to host sulfur and exchange both Li‐ions and electrons, effectively. In this hierarchical wire structure, porous CoMoS2 nanosheets form close interfaces with sulfur, and the CNT core directly transfers electrons to the sulfur‐impregnated CoMoS2. Simultaneously, the solid electrolyte positioned on the outer region of the nanowire material ensures facile Li‐ion conduction to the sulfur‐impregnated CoMoS2. An ASB featuring a CoMoS2@CNT host material with a sulfur loading of 3 mg cm−2 exhibits a high‐areal‐capacity of 4.5 mAh cm−2 at a current density of 2.5 mA cm−2, while retaining 79.4% of its initial capacity after 300 cycles. When sulfur is replaced with SeS2 to further reinforce the charge conduction properties, all‐solid‐state SeS2 batteries (ASeS2Bs) with an extremely high‐areal‐capacity of 16.3 mAh cm−2 retain 99.3% of their initial capacities after 60 cycles at 60 °C. This study provides guidelines for the design principles of cathode composites for the ASBs and ASeS2Bs through multiangle comparative analysis.

Multiwall carbon nanotube-hyperbranched polymaleimide core–shell nanowires with hierarchical porous and polar structure as sulfur host for sustainable lithium-sulfur batteries

Lithium–sulfur (Li–S) batteries have gained considerable attention as a promising alternative to current advanced batteries because of their low cost, natural abundance, high energy density, and environmental benignity of sulfur. The commercial application of Li–S batteries is being seriously impeded by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish reaction kinetics of solid phase transformation. Herein, a novel composite material (PPI@MWCNT-Y) with a hierarchical porous skeleton and polar channel is prepared as a sulfur host using a convenient in-situ one-pot polymerization. PPI@MWCNT-Y is composed of conductive mesoporous multi-wall carbon nanotubes (MWCNTs) core and a microporous hyperbranched polymaleimide (PPI) shell formed by the self-polymerization of N,N′-1,4-phenylenedimaleimide (PDM). The mesoporous and conductive channels in PPI@MWCNT-Y improve the redox kinetics of the active materials by serving as a fast electron and Li-ions transportation pathway. The microporous structure and abundant adsorption sites (N and O atoms) within the PPI@MWCNT-Y served as physical and chemical barriers, preventing the loss of LiPSs, and suppressing the shuttle effect. Consequently, the S/PPI@MWCNT-38 composite exhibited a high discharge capacity of 1338 mAh g−1 at 0.2 C and a low-capacity decay rate of 0.088% for 400 cycles at 1 C.

A nonlocal higher-order shear deformation approach for nonline ar static analysis of magneto-electro-elastic sandwich Micro/Nano-plates with FG-CNT core in hygrothermal environment

In this study, the nonlocal static analysis of Magneto-Electro-Elastic (MEE) sandwich micro/nano-plates with Functionally Graded Carbon Nanotubes (FG-CNTs) core in a hygrothermal environment is studied. The nonlocal static formulation is developed based on Reddy's High-order Shear Deformation theory (HSDT). The von Kármán nonlinear strains are used and the governing equations of the HSDT are derived accounting for Eringen's nonlocal stress-gradient model. The governing equations are solved using the Galerkin method, which involves expanding the displacement field based on orthogonal functions. The variation of the volume fractions through the thickness of FG-CNTs core layer has been computed using two different homogenization techniques: the rule of mixtures and the Mori–Tanaka scheme. A detailed parametric study to show the characteristics of the FG-CNTs core, nonlocal parameters, thermal and moisture changes, types of CNT reinforcement and volume fraction, electric and magnetic potentials, and geometric parameters. The results are compared with the first-order shear deformation theory (FSDT) and classical plate theory to show the accuracy of nonlocal High-order Shear Deformation theory(NHSDT) formulation.

Highly stretchable conductor with elastomeric passivation sheath enabling applications in harsh conditions

The rapid development of robotics requires stretchable electrical conductors capable of large deformations and having high operational stability in terms of electrical and mechanical characteristics. Carbon nanotubes (CNT) have been considered as the primary component of stretchable conductors, and mechanically drawn CNT sheets have shown their functionality when combined with various elastomeric materials in the shape of yarns. Herein, an electrically passivated stretchable conductor with an elastomer sheath and a spandex–CNT coiled-yarn core structure is reported. Based on the proven performance of spandex–CNT coiled-yarn, the electrical insulation by the Ecoflex elastomer enhances its applicability in an actual situation without degrading the stretchable conductor functionality. The experimental results show a substantial working deformation range (up to 350%), high durability, and low resistance variation during repetitive stretch and release cycles. Additionally, its stability is confirmed over a wide temperature range (up to 150 °C) and even inside an acidic liquid environment where the elastomeric sheath protects the conducting core. The perfect cooperation between the Ecoflex sheath and spandex–CNT core opens the possibility of deploying this stretchable conductor technology under harsh conditions.

Ultralow-Overpotential Acidic Oxygen Evolution Reaction Over Bismuth Telluride-Carbon Nanotube Heterostructure with Organic Framework.

The state-of-the-art iridium and ruthenium oxides-based materials are best known for high efficiency and stability in acidic oxygen evolution reaction (OER). However, the development of economically feasible catalysts for water-splitting technologies is challenging by the requirements of low overpotential, high stability, and resistance of catalysts to dissolution during the acidic oxygen evolution reaction . Herein, an organometallic core-shell heterostructure composed of a carbon nanotube core (CNT) and bismuth telluride (Bi2Te3) shell (denoted as nC-Bi2Te3) is designed and use it as a catalyst for the acidic OER. The proposed catalyst achieves an ultralow overpotential of 160mV at 10mAcm-2 (geometrical), thereby outperforming most of the state-of-the-art precious-metal-based catalysts. The low Tafel slope of 30mVdec-1 and charge transfer resistance (RCT)of 1.5Ω demonstrate its excellent electrocatalytic activity. The morphological and chemical compositions of nC-Bi2Te3 enable the generation of ─OH functional group in the Bi─Te sections formed via a ligand support, which enhances the absorption capacity of H+ ions and increases the intrinsic catalytic activity. The presented insights regarding the material composition-structure relationship can help expand the application scope of high-performance catalysts.

1D Magnetic MX3 Single-Chains (M = Cr, V and X = Cl, Br, I).

Magnetic materials in reduced dimensions are not only excellent platforms for fundamental studies of magnetism, but they play crucial roles in technological advances. The discovery of intrinsic magnetism in monolayer 2D van der Waals systems has sparked enormous interest, but the single-chain limit of 1D magnetic van der Waals materials has been largely unexplored. This paper reports on a family of 1D magnetic van der Waals materials with composition MX3 (M = Cr, V, and X = Cl, Br, I), prepared in fully-isolated fashion within the protective cores of carbon nanotubes. Atomic-resolution scanning transmission electron microscopy identifies unique structures that differ from the well-known 2D honeycomb lattice MX3 structure. Density functional theory calculations reveal charge-driven reversible magnetic phase transitions.

Crack‐Induced Superelastic, Strength‐Tunable Carbon Nanotube Sponges

AbstractLightweight strong aerogels have many applications, but they suffer from the trade‐off between key mechanical properties, and it remains challenging to realize superelastic aerogels simultaneously possessing high strength and excellent structural recovery. Herein, a strategy to overcome such a problem by designing a carbon nanotube (CNT)‐based aerogel consisting of flexible‐rigid core‐shell structure, which achieve a combination of excellent properties including superelasticity (complete recovery at 90%), high strength (over 12 MPa at 90%) and wide tunability (from 101 kPa to 4.5 MPa at 50% strain), is presented. It is found that the outer rigid but brittle amorphous carbon shells crosslink the CNT cores and crack into orderly distributed segments during the first compression cycle, while the flexible CNT cores ensure the integrity of the overall skeleton and tolerance to large deformation. This designed CNT composite sponges exhibit overall superior mechanical properties than previously reported foams/aerogels, and due to such unique crack‐induced superelasticity mechanism, potential applications such as pressure sensors with wide‐range tailored sensitivity and high‐performance energy absorbers have been developed. This flexible‐rigid core‐shell synergia may provide further insight for tunable high‐strength aerogel design and innovative applications.

Machine learning assisted nonlinear deflection analysis of agglomerated carbon nanotube core smart sandwich plate with three-phase magneto-electro-elastic skin

This research focuses on evaluating the combined effects of the interphase of the three-phase magneto-electro-elastic (TPMEE) composites and carbon nanotubes (CNTs) agglomeration on the nonlinear deflection of the multifunctional sandwich plate, using an artificial neural network (ANN) assisted finite-element (FE) approach. The data points collected from the in-house developed FE computational tool are used to train the ANN model. To this end, a backpropagation-based Levenberg–Marquardt algorithm is used. The core of the plate is made of agglomerated CNTs, and the facesheets are made of TPMEE composites. Two different agglomeration states, partial and complete, are considered for evaluation. Also, three variations of CNTs arrangement are assumed. On the other hand, the interphase effects are incorporated through its volume fractions and compositions. The plate kinematics is based on the higher-order shear deformation theory, and the nonlinearity is assumed to follow von Karman's strain-displacement relation. The equations of motion are derived using the total potential energy principle. Finally, the direct iterative method is used to arrive at the solutions. The numerical examples are also provided to understand the influence of coupling fields associated with the parameters, such as agglomeration, interphase volume fraction, interphase compositions and CNTs arrangement.

Lightweight Copper–Carbon Nanotube Core–Shell Composite Fiber for Power Cable Application

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO2 emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss in copper cables resulting in a decrease in coal and gas consumption, and ultimately diminishing the carbon footprint. In this work, we created a lightweight Cu–CNT composite fiber through a multistep scalable process, including spinning, densification, functionalization, and double-layer copper deposition. The characterization and testing of the fabricated fiber included surface morphology, electrical conductivity, mechanical strength, crystallinity, and ampacity (current density). The electrical conductivity of the resultant composite fiber was measured to be 0.5 × 106 S/m with an ampacity of 0.18 × 105 A/cm2. The copper-coated CNT fibers were 16 times lighter and 2.7 times stronger than copper wire, as they revealed a gravimetric density of 0.4 g/cm3 and a mechanical strength of 0.68 GPa, suggesting a great potential in future applications as lightweight power transmission cables.

Oxygen‐vacancy‐containing cerium oxide nanoparticle‐decorated nanonetwork‐structured carbon toward high‐performance lithium–sulfur batteries

AbstractLithium–sulfur (Li–S) batteries have been regarded as promising next‐generation energy‐storage devices owing to their inherently high theoretical energy density. Unfortunately, the poor capacity and cycling life caused by severe polysulfide shuttle effect and sluggish redox kinetics in sulfur cathodes greatly impede the practical application of Li–S batteries. Herein, a new class of nanonetwork‐structured carbon decorated with oxygen‐vacancy‐containing cerium oxide nanoparticles (NSC–CeO2−x), in which carbon skeleton is composed of highly conductive carbon nanotube core welded by hybrid carbon shell, has been developed via one‐step heating treatment of hybrid molecular brush and further employed as functional interlayer to modify separator of Li–S battery. Owing to the synergistic effect of the highly active CeO2−x nanoparticles and the three‐dimensional carbon nanonetwork in enhancing the preservation of the soluble polysulfides and boosting the redox kinetics of sulfur species, the NSC–CeO2−x significantly promotes the electrochemical performance of sulfur cathode. As a result, the as‐constructed Li–S batteries exhibit an ultrahigh initial sulfur utilization of 92.9% and an extremely large capacity of 751 mA h g−1 at a high rate of 5 C. Remarkably, a stable capacity of 728 mA h g−1 over 300 cycles at 1 C is also achieved.

Nanofibrous Cathode Catalysts with MoC Nanoparticles Embedded in N-Rich Carbon Shells for Low-Overpotential Li–CO2 Batteries

Li-CO2 batteries with high theoretical energy densities are recognized as next-generation energy storage devices for addressing the range anxiety and environmental issues encountered in the field of electric transportation. However, cathode catalysts with unsatisfactory activity toward CO2 absorption and reduction/evolution reactions hinder the development of Li-CO2 batteries with desired specific capacities and sufficient cycle numbers. In this work, a multifunctional nanofibrous cathode catalyst that integrates N-rich carbon shells embedded with molybdenum carbide nanoparticles and multiwalled carbon nanotube cores was designed and prepared. The N-rich carbon shell could strengthen the absorption capacity of CO2 and Li2CO3. The molybdenum carbide nanoparticles would improve the catalytic activity of both CO2 reduction and evolution reactions. The carbon nanotube cores would provide an efficient network for electron transportation. The synergistic effect of the cathode catalysts enhances the electrochemical performance of Li-CO2 batteries. A high cycling stability of more than 150 cycles at a current density of 250 mA g-1 with a cutoff capacity of 1000 mAh g-1 and a charge/discharge overpotential of less than 1.5 V is achieved. This work provides a feasible strategy for the design of a high-performance cathode catalyst for lithium-air batteries.

Nano-confinement coating strategy derived Matryoshka-like carbon nanotubes@anatase nanocrystalline@amorphous carbon nanofibers for ultrafast sodium ion storage

Titania is considered to be an attractive candidate as anode for sodium ion batteries due to excellent cycle stability, advanced safety features, and small volume deformation in the charge-discharge process. However, limited by sodium storage mechanism, the fast charge and discharge performance of multi-crystals titania is failed to satisfy the requirements of commercial application. Here, we develop a Matryoshka-like carbon nanotubes@anatase nanocrystalline@amorphous carbon (CNTs@aTiO2@C) nanofibers for ultrafast sodium ion storage. A nano-confinement coating strategy is demonstrated for constructing an intermediate layer assembled by ultrafine nanocrystalline (2-3 nm) of anatase. The synthesized Matryoshka-like nanofibers with diameters of ∼95 nm consists of amorphous carbon outer layer (10-13 nm), anatase nanocrystalline assembled intermediate layer (13-15 nm), and carbon nanotube core. Benefit from the ultra-refinement of anatase nanocrystalline and Matryoshka-like micro-morphology, the proportion of the capacitive-controlled contribution are up to 90.1 %, 90.6%, 91.9 %, 92.3%, and 93.6% with sweep rate increased from 0.2 to 0.4, 0.6, 0.8, and 1.0 mV s−1, thus result in an outstanding reversible specific capacities of ∼120 mA h g−1 with Coulombic efficiency of ∼99.5% after long-life of 10000 cycles at ultrafast rate of 10 A g−1.

Active control of nonlinear coupled transient vibrations of multifunctional sandwich plates with agglomerated FG-CNTs core/magneto-electro-elastic facesheets

This article investigates the controlled nonlinear transient response of sandwich plates made of magneto-electro-elastic (MEE) facesheets and agglomerated carbon nanotube (ACNT) core. The control is achieved by active constrained layer damping (ACLD) treatment which consists of piezoelectric (PE) and viscoelastic (VE) layers. The agglomeration is mathematically modelled using the Eshelby–Mori–Tanaka approach. The governing equations are derived under the framework of finite element (FE) methods using Hamilton’s principle and condensation technique. The VE patch of the ACLD treatment is modelled through the Golla–Hughes–McTavish method. This evaluation has considered two states of agglomerations, such as complete and partial agglomeration. The proposed FE model facilitates the integration of the three-field (magnetic, electric and elastic) coupling with the agglomeration and electromagnetic circuit effects, which makes this work interesting. It acts as a ready tool for the realistic design of a smart structure and system. In addition, the computational efforts and efficiency of the proposed FE model prove to be better than the commercial numerical software. Extensive numerical examples are solved to assess the influence of CNT distributions, electromagnetic circuits, coupling, mechanical boundary conditions, thickness configuration and ACLD patch position. This work serves as a novel benchmark solution for further research on the active control of agglomerated CNT structures.

Ni3S2 nanowires filled carbon nanotubes of ultra-high quality: Synthesis methods, structure, and electrical properties

The synergy between the host carbon nanotube (CNT) and the guest filler distinguishes the filled CNTs as hybrid nanomaterials with unique properties. Many materials have been filled inside the CNT cores using several strategies; however, a reliable filling method to encapsulate transition metal sulfide nanowires inside the CNTs is still lacking. An in situ method is developed for the first time to synthesize the Ni3S2 nanowires filled CNTs (Ni3S2@CNTs), and their fundamental properties are investigated. Electron microscopy results demonstrate a core-shell structure of Ni3S2@CNT, i.e., a CNT filled with a continuous and single-crystalline, rhombohedral Ni3S2 nanowire up to several micrometers in length. An exceptionally low value of the ratio between the intensities of D and G bands (ID/IG = 0.26) in the Raman spectroscopy measurements suggests that Ni3S2@CNTs are very well graphitized, possessing an ultra-high quality. A mean resistivity of 6.1 × 10−5 Ωm is estimated using both two probe and four-point probe measurements on individual Ni3S2@CNTs. Also, a diameter selective electrical breakdown or emptying of the filled nanotube channel is observed as higher currents pass through an individual Ni3S2@CNT.

Thiophilic-Lithiophilic Hierarchically Porous Membrane-Enabled Full Lithium-Sulfur Battery with a Low N/P Ratio.

Lithium-sulfur batteries stand out as the next-generation batteries because of their high energy density and low cost. However, the shuttle effect of lithium polysulfides (LiPSs), growth of lithium dendrites, and overuse of lithium resources still hinder their further application. To address these problems, we constructed a porous network structure in which Sn is melted and coated on a frame that has a carbon nanotube (CNT) core and a nitrogen-doped carbon (NC) coating as cross-linking shell (CNT@NC@Sn). This hierarchically porous membrane electrode, which has an ultrahigh porosity of approximately 90%, works as a matrix to strengthen the conductivity of Li+ and electrons and provides enough space for the conversion between sulfur and LiPSs. Moreover, the in situ thin coating of Sn not only promotes the adsorption and catalytic conversion of LiPSs but also provides lithiophilic binding sites and induces uniform lithium deposition. Thus, the thiophilic-lithiophilic porous membrane electrode with lithium loaded on the frame (in the form of Sn-Li alloy) by electroplating can replace lithium sheets, reduce the use of Li, and improve the safety performance of the battery. Additionally, these dual-functional membranes boost the reaction kinetics and conductivity of the cathode by dispersing the sulfur slurry in the porous membrane framework. As a result, the lithium-sulfur full battery assembled with the CNT@NC@Sn integrated membrane electrode exhibits stable cycling with a reversible capacity of 617.1 mAh g-1 after 200 cycles at 1 C. The capacity decay rate per cycle is 0.105%, and the N/P ratio is as low as 2.98.

Intertube Excitonic Coupling in Nanotube Van der Waals Heterostructures (Adv. Funct. Mater. 11/2022)

Intertube Excitonic Coupling In article number 2104969, James Lloyd-Hughes and co-workers demonstrate strong intertube excitonic coupling in 1D van der Waals heterostructures comprising C/BN/MoS2 core/shell/skin nanotubes. Remarkably, infrared excitation of excitons in the carbon nanotube core creates a prominent excitonic response in the visible range from the MoS2 skin. Via classic analogies and a quantum model of the light–matter interaction these findings are assigned to intertube excitonic correlations.

Stress distribution of a cylindrical sandwich sector with FG-CNT core and piezoelectric face sheets subjected to low-velocity impact

A new theoretical solution based on Layerwise theory is presented to determine the stress distribution in a simply-supported cylindrical sandwich sector with a functionally graded carbon nanotube core and piezoelectric face sheets subjected to low-velocity impact. The spherical elastic ball hits the top face sheet of the sector at an initial velocity of 50 m/s. The classical non-adhesive elastic contact theory and Hunter's relationship were used to determine the normal contact pressure distribution in terms of time and distance of the contact location. Moreover, Hamilton's principle and Maxwell's static equation were used to obtain the nineteen equations of motion. The numerical code was written to solve these nonlinear equations and the stress components in each layer were calculated in terms of time. In addition, it was assumed that the out-of-shell displacement of the sector at each layer is a quadratic polynomial function of the radial component in addition to a function of the coordinate components within the shell. Due to this assumption, the normal out-of-shell strain is not only zero, or not even a constant, but it changes in the form of a linear function along with the thickness of each layer.

Selenium-doped carbon nanotubes/nickel selenide coaxial nanocables for energy storage

Coaxial nanocable heterostructures consisting of highly conductive carbon nanomaterial core and active transition-metal compound sheath are promising potential candidates for advanced energy storage materials. Herein, the multi-functional selenium‐doped carbon nanotubes/nickel selenide coaxial nanocables with chemical bonding interface are prepared by using an electroless deposition combined with the following chemical vapor reaction process, in which the nickel layer is first deposited onto the carbon nanotube core and subsequently transformed in-situ into the nickel selenide sheath by the controlled selenization reaction at elevated temperature. Such coaxial structure provides the large active material/electrolyte contact area, and the fast diffusion and transfer of mass and charge in the electrochemical process, thus which endows superior supercapacitive and good lithium storage performances. The coaxial nanocables exhibit a high specific capacity of 340.0 mAh g −1 at 1 A g −1 as an electrode for supercapacitor, and a lithium storage capacity of 600.0 mAh g −1 at 0.1 A g −1 as an anode for lithium-ion batteries. A supercapacitor based on the nanocables delivers a high energy density of 70.0 Wh kg −1 at 803.0 W kg −1 and long cycling stability with 65.0% capacitance retention after 8000 cycles at 10 A g −1 . • Preparing multi-functional Se-CNTs@NiSe nanocables with chemical bonding interface. • Graphene/NiSe nanoribbons are derived due to splitting of coaxial nanocables. • Nanocables show the excellent supercapacitive and lithium storage performances.

One-dimensional covalent organic framework—Carbon nanotube heterostructures for efficient capacitive energy storage

Covalent organic frameworks (COFs) with redox-active moieties are potential capacitive energy storage materials. However, their performance is limited by their poor electrical conductivity and sluggish ion diffusion in their nanopores. Herein, we report coaxial one-dimensional van der Waals heterostructures (vdWHs) comprised of a carbon nanotube (CNT) core and a pyrene–pyridine COF shell synthesized by an in situ wrapping method. The coaxial structure allows efficient electronic interaction between the CNT core and COF shell and improves the electrical conductivity significantly. It also improves electrolyte ion accesses to redox-active pyridine groups in the COF, resulting in excellent capacitive energy storage performance with a high specific capacitance of ∼360 F g−1, an excellent rate capability of ∼80%, and a good stability of 92% capacitance retention after 20 000 charge/discharge cycles. Our strategy opens the door to create other multi-dimensional vdWHs for various potential applications.

Durable n-type carbon nanotubes double-doped with 1,8-diazabicyclo[5.4.0]undec-7-ene and polyamidoamine dendrimers

Owing to their well-known instability in air, organic n-type semiconductors must be doped to protect them from moisture and oxygen. Such doping is crucial for producing soft flexible devices that can convert large amounts of low-temperature waste heat into electrical energy. Herein, we report the preparation and thermoelectric properties of drop-cast carbon nanotube (CNT) films double-doped with the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) superbase and electron-donating polyamidoamine dendrimers (PAMAM). Our method not only enhances the chemical stabilities of the electron carriers but also is favorable for large-scale applications. Despite being prepared in aqueous solvents, the p-type CNTs were found to exhibit n-type behavior, irrespective of the pKa of the electron-donating organic molecule. In particular, the addition of DBU resulted in the largest thermoelectric conversion output factor (Seebeck coefficient and power factor of −32.2 μV K−1 and 261 μW m−1 K−2, respectively). The inclusion of PAMAM as a dispersant and secondary dopant significantly prolonged the stability of the n-type behavior of DBU-doped CNTs in air at 80 °C from approximately 15 days for an undoped system to more than 30 days. Surprisingly, after 30 days, the thermoelectric conversion power factor of the doped system was found to be approximately 20% higher than that of the undoped system, confirming the excellent performance of hybrid thermoelectric material with a PAMAM shell/DBU-doped CNT core structure. In addition, its n-type doping process does not require organic solvents. These results create new avenues for the development of atmospherically stable drop-cast n-type CNT films.