Nanotube Core Research Articles

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.

Parameteric optimization of SiGe S/D NT JLFET using analytical modeling to improve L‐BTBT induced GIDL

AbstractIn the present work, we investigate the impact of structure dimensional parameters on the short channel effects which occurs especially below 20 nm regime particularly gate induced drain leakage (GIDL) current. Using technology computer aided design simulation (TCAD), we have examined the GIDL for SiGe as source/drain in NTJLFET. The structural dimensional parameters such as the nanotube thickness, core and outer gates thickness and gate electrode work function shows the significant impact on the band to band tunneling in lateral direction (L‐BTBT) which induced GIDL current. It is analyzed that increase in the nanotube thickness and physical oxide thickness increase the GIDL current, while increasing the gate electrode work function, core gate and outer gate thicknesses gives reduced GIDL current. The SiGe S/D NTJLFET produce a remarkable high ION/IOFF ratio ~ 1011. A compact model for GIDL current is also developed which shows the dependency of structure parameters on leakage current. The SiGe has been incorporated as source and drain in NTJLFET which creates the energy band discontinuity. Furthermore, SiGe S/D NTJLFET is fairly compared with the conventional NT JLFET and nanowire (NW) JLFET and shows an improved performance.

Encapsulation of Uranium Oxide in Multiwall WS2 Nanotubes.

Uranium is a high-value energy element, yet also poses an appreciable environmental burden. The demand for a straightforward, low energy, and environmentally friendly method for encapsulating uranium species can be beneficial for long-term storage of spent uranium fuel and a host of other applications. Leveraging on the low melting point (60°C) of uranyl nitrate hexahydrate and nanocapillary effect, a uranium compound is entrapped in the hollow core of WS2 nanotubes. Followingly, the product is reduced at elevated temperatures in a hydrogen atmosphere. Nanocrystalline UO2 nanoparticles anchor within the WS2 nanotube lumen are obtained through this procedure. Such methodology can find utilization in the processing of spent nuclear fuel or other highly active radionuclides as well as a fuel for deep space missions. Moreover, the low melting temperatures of different heavy metal-nitrate hydrates, pave the way for their encapsulation within the hollow core of the WS2 nanotubes, as demonstrated herein.

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.

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.

Ion Adsorption and Desorption in a Hollow Core of a Single-Walled Carbon Nanotube

Ion Adsorption and Desorption in a Hollow Core of a Single-Walled Carbon Nanotube

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.

MIL-68 (In)-derived In2O3@TiO2 S-scheme heterojunction with hierarchical hollow structure for selective photoconversion of CO2 to hydrocarbon fuels

The hierarchical hollow structured photocatalysts of TiO2 nanosheet arrays-decorated In2O3 hexagonal nanotubes (core–shell structural In2O3@TiO2) were successfully fabricated by the in-situ hydrothermal method. Hierarchical hollow structure of In2O3@TiO2 photocatalysts with large specific surface area can improve the light harvesting efficiency and the adsorption capability for CO2 and H2O reactants. The internal electric field in In2O3@TiO2 photocatalysts provides the strong driving force for S-scheme electron transfer from conduction band of TiO2 to valence band of In2O3. The In2O3@TiO2 catalysts exhibited super performance for selectively photocatalytic CO2 conversion with H2O into hydrocarbon fuel (CH4) without sacrificial agent. Among the catalysts, In2O3@TiO2-10 catalyst has the largest yield (11.1 μmol g−1h−1) and selectivity (88.1 %) of CH4 product. Based on results of the characterizations, the mechanism of selective CO2 photoreduction is proposed: the surface enrichment of photogenerated electron induced by the S-scheme In2O3-TiO2 heterojunction is key-step for selective CO2 photoreduction into CH4. This work provides new ideas for the design and construction of high-efficient S-scheme photocatalysts.

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.

A physics-based drain current model for Si1-xGex source/drain NT JLFET for enhanced hot carrier reliability with temperature measurement

In this paper, we report, the hot carrier reliability issue in the Si1-xGex source/drain nanotube (NT) junctionless field-effect transistor (JLFET) with temperature variations. The surface potential, electric field and drain current have been formulated by developing a physics-based analytical model. SiGe in the source/drain regions creates valence band discontinuity of ΔEg = 0.23 eV which significantly increases the tunneling width at the channel/drain interface and therefore, results in a diminished L-BTBT action. The results demonstrate that at T = 500 K, drain current with the influence of interface trap charges in the Si1-xGex S/D architecture shows better immunity than the conventional NTJLFET. The Si1-xGex S/D enhances the reliability of analog/RF parameters such as transconductance (gm), intrinsic gain (gm/gd), cut-off frequency (fT), and gain-transconductance-frequency-product (GTFP), against the hot carriers. We have also explored the reliability with germanium (Ge) content, x and observed that for Ge content above x = 0.3, the reliability degrades in terms of higher electron temperature, reduced gm, and lower fT. The analytical results are verified and are in good agreement with results of Sentaurus TCAD simulations. The Si1–xGex S/D architecture combined with NT core gate can help relieve the HCI trap charge reliability for JLFETs leading to significantly improved analog/RF parameters.

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.

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.