Embedded Carbon Nanotubes Research Articles

Sodium chloride solution transport through a carbon nanotube with an embedded carbon nanotube via molecular dynamics simulations

Carbon nanotubes hold significant potential for developing highly efficient desalination membranes. However, achieving both enhanced water transfer rate and salt rejection efficiency simultaneously has been challenging due to the pore size limitation. In this study, we discovered that embedding a carbon nanotube within a large-diameter carbon nanotube enables the simultaneous enhancement of both water transfer rate and salt rejection efficiency. This outcome is attributed to the accelerated water velocity and the blockage of ions entering the narrowed cross-section of the carbon nanotube. These findings have valuable implications for the design of fast water transport membranes with high salt rejection efficiency.

Ultra-Large Stress and Strain Polymer Nanocomposite Actuators Incorporating a Mutually-Interpenetrated, Collective-Deformation Carbon Nanotube Network.

Stimulus-responsive polymer-based actuators are extensively studied, with the challenging goal of achieving comprehensive performance metrics that include large output stress and strain, fast response, and versatile actuation modes. The design and fabrication of nanocomposites offer a promising route to integrate the advantages of both polymers and nanoscale fillers, thus ensuring superior performance. Here, it is started from a three-dimensional (3D) porous sponge to fabricate a mutually interpenetrated nanocomposite, in which the embedded carbon nanotube (CNT) network undergoes collective deformation with the shape memory polymer (SMP) matrix during large-degree stretching and releasing, increases junction density with polymer chains and enhances molecular orientation. These features result in substantial improvement of the overall mechanical properties and during thermally actuated contraction, the bulk SMP/CNT composites exhibit output stresses up to 19.5 ± 0.97MPa and strains up to 69%, accompanied by a rapid response and high energy density, exceeding the majority of recent reports. Furthermore, electrical actuation is also demonstrated via uniform Joule heating across the self-percolated CNT network. Applications such as low-temperature thermal actuated vascular stent and wound dressing are explored. These findings lay out a universal blueprint for developing robust and highly deformable SMP/CNT nanocomposite actuators with broad potential applications.

Nonlinear phenomena in vibrations of embedded carbon nanotubes conveying viscous fluid

Various nonlinear phenomena such as bifurcations and chaos in the responses of carbon nanotubes (CNTs) are recognized as being major contributors to the inaccuracy and instability of nanoscale mechanical systems. Therefore, the main purpose of this paper is to predict the nonlinear dynamic behavior of a CNT conveying viscous fluid and supported on a nonlinear elastic foundation. The proposed model is based on nonlocal Euler–Bernoulli beam theory. The Galerkin method and perturbation analysis are used to discretize the partial differential equation of motion and obtain the frequency-response equation, respectively. A detailed parametric study is reported into how the nonlocal parameter, foundation coefficients, fluid viscosity, and amplitude and frequency of the external force influence the nonlinear dynamics of the system. Subharmonic, quasi-periodic, and chaotic behaviors and hardening nonlinearity are revealed by means of the vibration time histories, frequency-response curves, bifurcation diagrams, phase portraits, power spectra, and Poincaré maps. Also, the results show that it is possible to eliminate irregular motion in the whole range of external force amplitude by selecting appropriate parameters.

Spray deposited carbon nanotube embedded ZnO as an electrons transport layer in inverted organic solar cells

In this report, the synthesis and characterization of ZnO and carbon nanotube (CNT) embedded ZnO composite thin films are presented. The obtained ZnO and CNT composite ZnO thin films are used as an electron transport layer (ETL) for bulk heterojunction (BHJ) inverted organic solar cell (IOSC) with the architecture of ITO/ZnO:CNT/PTB7:PC71BM/MoO3/Ag. Both ZnO and CNT composite ZnO thin films exhibited a highly preferred c-axis oriented (002) diffraction peak and the peak position is shifted toward a lower angle after embedding CNT into the ZnO matrix. The transmittance slightly decreases after CNT is embedded into the ZnO matrix. Completely wrapped CNT with the ZnO was confirmed by Scanning electron microscope (SEM) measurement. The resistivity of ZnO decreased from 2.02 × 10−2 to 5.61 × 10−3 Ω-cm and mobility increased from 4.30 to 15.24 cm2/V-s after adding CNT into the ZnO matrix. CNT composite ZnO thin film surface is found to be hydrophobic, providing good interfacial contact with the BHJ layer resulting to improve fill factor (FF) of IOSC. The performance of IOSC with CNT composite ZnO ETL layer was significantly improved with a power conversion efficiency of 6.76%, open circuit voltage (VOC) of 700 mV, short circuit current density (JSC) of 20.05 mA/cm2 and FF of 48.17%, respectively.

Substrate Strain Engineering of Single-Atomic Sn-N4 Sites Embedded in Various Carbon Matrixes for Bifunctional Oxygen Electrocatalysis

It is still a great challenge to design and synthesize high-efficiency and low-cost single-atom catalysts (SACs) as promising bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Herein, theoretical insights into Sn-N4 embedded carbon nanotubes, graphene quantum dots, and graphene nanosheets (denoted as Sn-N4-CNTs, Sn-N4-GQDs, and Sn-N4-Gra, respectively) for the ORR/OER are systematically provided. These results show that the protruding Sn atom creates a Sn-N4 pyramid and induces varied strain transfer between Sn-N4 and different carbon substrates prior to adsorption of O intermediates, resulting in the opposite response of the adsorption strengths of O intermediates to the substrate curvature of Sn-N4-CNTs and Sn-N4-GQDs. The torsional strain induced by OH* and OOH* on the Sn atom of Sn-N4-CNTs breaks the scaling relations between the adsorption strengths of O intermediates. Consequently, Sn-N4-CNTs with suitable curvature achieve outstanding ORR performance with very low overpotentials (0.28 V). Furthermore, the increase of curvature boosts the OER activity of Sn-N4-CNTs. For Sn-N4-GQDs, high curvature contributes to promoted OER activity but reduced ORR activity. The electronic interactions reveal the electron transfer from the s/p-bands of Sn to the half-filled β states of the frontier orbitals of O intermediates.

Percolation Effects in Mixed Matrix Membranes with Embedded Carbon Nanotubes.

Polymeric membranes with embedded nanoparticles, e.g., nanotubes, show a significant increase in permeability of the target component while maintaining selectivity. However, the question of the reasons for this behavior of the composite membrane has not been unequivocally answered to date. In the present work, based on experimental data on the permeability of polymer membranes based on Poly(vinyl trimethylsilane) (PVTMS) with embedded CNTs, an approach to explain the abnormal behavior of such composite membranes is proposed. The presented model considered the mass transfer of gases and liquids through polymeric membranes with embedded CNTs as a parallel transport of gases through the polymeric matrix and a "percolation" cluster-bound regions around the embedded CNTs. The proposed algorithm for modeling parameters of a percolation cluster of embedded tubular particles takes into account an agglomeration and makes it possible to describe the threshold increase and subsequent decrease permeability with increasing concentration of embedded particles. The numerical simulation of such structures showed: an increase in the particle length leads to a decrease in the percolation concentration in a matrix of finite size, the power of the percolation cluster decreases significantly, but the combination of these effects leads to a decrease in the influence of the introduced particles on the properties of the matrix in the vicinity of the percolation threshold; an increase in the concentration of embedded particles leads to an increase in the probability of the formation of agglomerates and the characteristic size of the elements that make up the percolation cluster, the influence of individual particles decreases and the characteristics of the percolation transition determine the ratio of the sizes of agglomerates and matrix; and an increase in the lateral linear dimensions of the matrix leads to a nonlinear decrease in the proportion of the matrix, which is affected by the introduced particles, and the transport characteristics of such MMMs deteriorate.

Enhanced Hydrogen Evolution Reaction over Co Nanoparticles Embedded N-Doped Carbon Nanotubes Electrocatalyst with Zn as an Accelerant.

The rational design for transition metals-based carbon nano-materials as efficient electrocatalysts still remains a crucial challenge for economical electrochemical hydrogen production. Carbon nanotubes (CNTs) as attractive electrocatalysts are typically activated by non-metal dopant to promote catalytic performance. Metals doping or metal/non-metal co-doping of CNTs, however, are rarely explored. Herein, this work rationally designs bimetal oxide templates of ZnCo2 O4 for heterogeneously doping Zn and N into Co nanoparticles embedded carbon nanotubes (Co@Zn-N-CNTs). During the formation of CNTs, Zn atoms volatilize from ZnCo2 O4 and in situ dope into the carbon skeleton. In particular, owing to the low electronegativity of Zn, the electrons aptly transfer from Zn to carbon atoms, which generate a high electron density for the carbon layers and offermore preponderant catalytic sites for hydrogen reduction. The Co@Zn-N-CNTs catalyst exhibits enhanced hydrogen evolution reaction activity in 0.5m H2 SO4 electrolyte, with a low onset potential of -20mV versus RHE at 1mA cm-2 , an overpotential of 67mV at 10mA cm-2 , a small Tafel slope of 52.1mV dec-1 , and persistent long-term stability. This study provides brand-new insights into the utilization of Zn as electronic regulator and activity promoter toward the design of high-efficiency electrocatalysts.

Nanoarchitectonics with NiFe-layered double hydroxide decorated Co/Ni-carbon nanotubes for efficient oxygen evolution reaction electrocatalysis

• NiFe-LDH decorated Co/Ni-carbon nanotube nanoarchitectonics was fabricated. • The nanotubes enhanced the conductivity and improved the distribution of NiFe- LDH. • The nanoarchitectonics revealed efficient oxygen evolution reaction (OER) performance. • The result provided a feasible approach to get excellent OER electrocatalysts. To face the application request of electrocatalytic overall water splitting, developing highly efficient and cost-effective catalysts for water splitting, especially for oxygen evolution reaction (OER) is yet challenging. In this work, NiFe-layered double hydroxides (NiFe-LDHs) are grown on the bimetallic (Ni and Co) embedded carbon nanotubes to get efficient catalysts for excellent OER performance, in which 267 mV is required to reach the current density of 10 mA cm −2 in 1 M KOH solution without iR-compensation. The formation of carbon nanotubes significantly enhances the conductivity and alleviates the agglomeration of NiFe-LDHs, meanwhile, the bimetallic carbon substrate/nanotube is employed as a bridge to drive electrons transfer to NiFe-LDHs. The redistribution of electrons makes NiFe-LDHs in an electron-rich situation. The regulation of the electronic situation adjusts the bonding strength between the active sites and oxygen intermediates to promote the deprotonation process.

Metal-organic frameworks derived carbon nanotube and carbonyl iron composite materials for broadband microwave absorbers with a wide filling range

• CI/CNT composite was obtained by epitaxial growth-pyrolysis scheme. • Embedding CNT between CI sheets, it exhibits great EMWA in a wide filling range. • By the meta-structure design, the composite achieved RL < −10 dB in 2–18 GHz. Magnetic carbon-based composites derived from metal organic frameworks (MOFs), with tunable morphology and highly dispersed magnetic particles, show great potential as electromagnetic wave absorbing (EMWA) materials. Here, a composite with carbon nanotube (CNT) embedded only between the gaps of carbonyl iron (CI) sheets were obtained, which was achieved by controlling the collapse state of the MOF skeleton during pyrolysis. The unique distribution can prevent the production of global conduction channels, resulting in the impedance matching between air and the composites in the broadened filling range. The composite thus can achieve a broadband absorption in the frequency range of 2–18 GHz by structure design. This work provides a new approach for EMWA materials to reduce the preparation difficulty of broadband absorbers.

MXene/CNTs/Cu-MOF electrochemical probe for detecting tyrosine

Tyrosine is the precursor of some neurotransmitters such as thyroxine and dopamine. It has the effect of regulating emotions and stimulating the nervous system. Changes in tyrosine levels in the human body are associated with certain diseases. Therefore, it is very necessary to prepare a new type of tyrosine sensor. In this work, an enzyme-free electrochemical sensor based on MXene/CNTs/CuMOF composite was developed for the detection of tyrosine. Embedding carbon nanotubes (CNTs) into MXene effectively prevented the aggregation of MXene sheets. Further modification of MXene/CNTs materials with CuMOF octahedral particles with porous structure can improve the porosity and catalytic capability of the composites. Under the optimal detection conditions, the prepared sensor has good linearity in the detection of tyrosine within range 0.53 μM–232.46 μM with a limit of detection (LOD) of 0.19 μM. The stability and selectivity of the sensor is high, and can be used to detect tyrosine in human serum.

DNA foams constructed by freeze drying and their optoelectronic characteristics

The distinctive properties of DNA make it a promising biomaterial to use in nanoscience and nanotechnology. In the present study, DNA foam was fabricated into multi-dimensional shapes using a freeze drying process with liquid nitrogen and 3D printed molds. The physicochemical and optoelectronic properties of the fabricated DNA foams were investigated using Fourier transform infrared (FTIR) spectrum, X-ray photoelectron spectrum (XPS), thermogravimetric analysis (TGA), ultraviolet-visible (UV-Vis) absorption spectrum, and current-voltage (I-V) characteristics to understand the changes formed in the DNA structure and their effect on properties during the fabrication of DNA foam. The FTIR and XPS analyses confirmed that nitrogen was diffusing into the DNA structure during the DNA foam fabrication. The diffused nitrogen caused a decrease in bond lengths, strong chemical bonds, compaction of DNA structure, existence of additional carbon-nitrogen bonds, and variation in the electron density of the base elements in DNA. These changes in the DNA structure of the DNA foam were reflected in their chemical, optical, and electrical properties. Furthermore, the proper utilization of DNA foams as a template for functional materials by embedding carbon nanotubes (CNTs) and thermocolor was demonstrated.

Research on the Performance of Composite Cantilever Beam under Special Environmental Condition

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;This paper will focus on the root facture problem of carbon fibre reinforced polymers (CFRP) material of aircraft winglets through ABAQUS simulation analysis regarding the aircraft takeoff and landing from high altitude at the constant and low-temperature experimental analysis and topography analysis. The innovative purpose of this paper is to identify the critical failure stress of the cantilever bending of unidirectional and orthogonal, embedding carbon nanotube reinforcement, and exploring the embedded carbon nanotube regarding the enhancement effect of CFRP aircraft winglet. First of all, the analysis of the force state of the aircraft winglet, the unidirectional and orthogonal CFRP aircraft winglet at normal temperature, and low- temperature cycling is established based on the principle of classic laminates and statics. The wing cantilever bending critical failure stress mechanics model provides a theoretical basis for the influence of low- temperature cycles on aircraft winglets. Secondly, verifying the correctness of the above-mentioned mechanical model, the CFRP aircraft winglet was studied through bending stress analysis, stress- displacement curve analysis, and sample topography analysis. Finally, the equipment for preparing embedded carbon nanotubes CFRP composite material was designed to ensure the accuracy of the test piece and explored the effect of embedded carbon nanotubes on the CFRP aircraft winglet. The main reason for the weakening of the winglet cantilever anti-bending strength is the fibre. During the low-temperature cycle, the residual stress generated by the aircraft winglet fiber’s repeated damp and heat deformation is too weak to increase the wing's cantilever bending failure critical stress. The enhanced result of the cantilever anti-bending ability and the microscopic mechanism of action provides the basis of the carbon nanotube reinforcement medium to the CFRP aircraft winglet development.&lt;/div&gt;&lt;/div&gt;

Dependence of the conductivity of PEDOT:PSS-Carbon nanotubes composite films on the deposition method

The dependence of conductivity of the composite PEDOT:PSS with embedded carbon nanotubes films on the method of its preparation was investigated. Especially, a method of layer-by-layer deposition of carbon nanotubes and the method of film deposition from a mixture of PEDOT:PSS with carbon nanotubes (CNT) are compared. The electrophysical film parameters were obtained from a four-point probes measurements while optical parameters from spectroscopic ellipsometry. Our results showed that the method of layer-by-layer deposition of CNT and PEDOT:PSS allows one to obtain films with higher conductivity (≈170–180 S/cm) compared to the method of depositing a film from their mixture (≈62–92 S/cm).

Radiative Cooling and Solar Heating Janus Films for Personal Thermal Management

Hot and cold seasonal temperature fluctuations pose a serious public health threat. Radiative thermal management has been shown to be an effective method for personal thermal management. However, the currently available materials cannot maintain human thermal comfort against the hot and cold seasonal temperature fluctuations, such as heating in cold weather or cooling in hot weather. Here, a Janus film that integrates the two opposite requirements of heating and cooling into one functional dual-mode film is fabricated. In cooling mode, the Al backing and embedded silicon dioxide (SiO2) microparticle can achieve a high solar reflectivity (∼0.85) and high IR emissivity (∼0.95) to induce a temperature drop of ∼2 °C. In contrast, the embedded carbon nanotubes (CNTs) can improve solar absorption (∼0.95) and induce a temperature increase of ∼7 °C. Owing to its radiative cooling and solar heating capability and compatibility with large-scale production, this Janus film is promising to bring new insights into the design of the next-generation functional textiles.

Priority Occupation of C-Sites by N-Confining P-Implantation in Pyrrodic N-Sites in NCNT@P,N-Mo2C for Highly Efficient Electrocatalytic Hydrogen Evolution.

Optimizing the electronic configuration of Mo2C by activating heteroatom(s)-neighboring carbon atoms to enhance the activity of hydrogen evolution reaction (HER) has been demonstrated. However, the development of heteroatom-doped Mo2C to fabricate a water electrolyzer is still a challenge because of the limitation of a well-defined electronic structure of hybridization of Mo with heteroatom(s). Here, nitrogen (N) and phosphor (P) codoped Mo2C embedded carbon nanotubes (NCNT@P,N-Mo2C) with the priority occupation of C-sites by N, which well confines the P-implantation at the pyrrodic N-sites and brings out N-O bonding on the surface, which favorably modifies the electronic configuration of adjacent Mo, resulting in highly efficient pH-tolerant HER activity. This study not only presents a potential HER electrocatalyst candidate but also provides a strategy for the construction of a well-defined electronic structure of heteroatom(s)-neighboring carbon-based materials.

Conductive reverse osmosis membrane for electrochemical chlorine reduction and sustainable brackish water treatment

The susceptibility of RO membrane for chlorine, which is widely used for disinfecting the feedwater, remains a biggest challenge. Herein for the first time, we report an electrochemical chlorine reduction on a conductive RO membrane interface as a sustainable solution to overcome this limitation. In this study, cyclic voltammetry was employed to investigate the potential of electrochemical chlorine reduction. Later, a conductive RO membrane with an embedded carbon nanotubes layer (CNT-RO) was fabricated, and its resistance to chlorine was tested via batch soaking into a sodium hypochlorite solution (NaOCl; 1,000 ppm; pH = 5) used as the chlorine source, followed by the flux and salt rejection monitoring.The CNT-RO membrane resulted in 3.5% and 9.3% chlorine uptake after chlorinating for 1 h and 24 h, hence faced prominent decline in the amide II and aromatic amide peak positioned at 1541 cm−1 and 1609 cm−1, respectively. In contrast, the application of 2 V on conductive CNT-RO membrane interface when used as a cathode resulted in an irreversible chlorine reduction, hence formed chloride as validated via ion chromatography. Chlorination of CNT-RO membrane under conducting mode could not cause any significant change in the membrane morphology, elemental composition, amide bonding structure, and surface wettability. Therefore, CNT-RO membrane demonstrated 88% rejection against monovalent salt even after 24 h of chlorination under conducting mode as compared to the commercial and CNT-RO (chlorinated without DC charge application) which showed 69% and 74% rejection, respectively. These findings clearly illustrated the potential of conductive RO membrane for sustainable desalination and water reuse applications.

ИССЛЕДОВАНИЕ НАНОКОМПОЗИТА НА ОСНОВЕ АЛЮМИНИЯ, УПРОЧНЕННОГО УГЛЕРОДНЫМИ НАНОТРУБКАМИ

aluminum-based nanocomposites reinforced with carbon nanotubes were studied by computational calculations. Numerical simulations were performed within the framework of density functional theory using the plane wave basis set implemented in VASP software package. Non-local van der Waals functional was used to describe. For modeling of aluminum-based composites with large-diameter nanotubes the limiting case of the interface of the graphene/aluminum species was considered. The values of 4.3 meV/Å2 and 18.1 meV/Å2 respectively, were obtained, which are comparable with the van der Waals interaction energies by order. It is also obtained that the critical shear stress value for the defect-free graphene/aluminum system varies from 20 MPa to 70 MPa, depending on the surface type and "armchair" or "zigzag" shear direction. The influence of carbon monovacancies on mechanical properties of the composite was studied. Critical shear stress values of 1500-2000 MPa were obtained for energetically advantageous configurations of composites, depending on defect location, surface type and shear direction. The formation energies of the defects were determined. Finally, the alumina matrix composites with small diameter embedded carbon nanotubes are considered. It is shown that with a decrease in the size of the nanotube its surface curvature is observed and, as a consequence, the binding energy at the interface with the metal matrix is increased. Calculated values of critical stress reach values of the order of ~103 MPa.

Strain-Sensing Characteristics of Carbon Nanotube Yarns Embedded in Three-Dimensional Braided Composites under Cyclic Loading

Carbon nanotube yarns are embedded in three-dimensional (3D) braided composites with five-axis yarns, which are used as strain sensors to monitor the damage of 3D braided composites. In the cyclic mechanical loading experiment, the strain-sensing characteristics of 3D braided composites were studied by in situ measuring the resistance change of the embedded carbon nanotube yarn. The 3D five-directional braided composite prefabricated part based on carbon nanotube yarns was developed, and the progressive damage accumulation experiments were carried out on carbon nanotube yarns and specimens embedded in carbon nanotube yarns. The research results show that there is a good correlation between the change of relative resistance of the carbon nanotube yarn and the strain of the composite specimen during cyclic loading and unloading. When the tensile degree of the specimen increases beyond a certain range, the carbon nanotube yarn sensor embedded in the specimen shows resistance hysteresis and produces residual resistance. Therefore, the fiber can better monitor the progressive damage accumulation of 3D five-direction braided composites.

In-situ damage sensing in intra-ply glass/carbon laminate composites under interlaminar shear loading

An experimental study is preformed to investigate the in-situ damage sensing capabilities of intra-ply hybrid carbon/glass laminate and epoxy composites under quasi-static interlaminar shear loading. A three-dimensional electrical sensory network is generated inside the composites through embedded carbon nanotubes (CNTs) in an epoxy matrix along with the carbon fibers in the intra-ply hybrid laminates. CNTs are dispersed in the epoxy matrix using a combination of ultrasonication and shear mixing techniques. Four circumferential ring probes are used to examine the electrical response under interlaminar shear load. The effect of four different intra-ply orientations (((0–90)C, where carbon fibers are oriented along the loading direction), ((0–90)G, where glass fibers are oriented along the loading direction), ((45/−45, where glass and carbon fibers are oriented at 45o/−45o and the laminates are repeated), and ((45/−45)A, where glass and carbon fibers are oriented at 45o/−45o and the laminates are alternated)) on the shear constitutive behavior and the damage detection are discussed. Intra-ply orientations of (45/−45) and (45/−45)A showed higher interlaminar shear strength and shear strain at break compared to (0/90)C and (0/90)G orientations. Out of all four orientations, (45/−45)A provided a better resolution of electrical response for damage sensing applications.

Chitosan-Based Flexible Memristors with Embedded Carbon Nanotubes for Neuromorphic Electronics.

In this study, we propose high-performance chitosan-based flexible memristors with embedded single-walled carbon nanotubes (SWCNTs) for neuromorphic electronics. These flexible transparent memristors were applied to a polyethylene naphthalate (PEN) substrate using low-temperature solution processing. The chitosan-based flexible memristors have a bipolar resistive switching (BRS) behavior due to the cation-based electrochemical reaction between a polymeric chitosan electrolyte and mobile ions. The effect of SWCNT addition on the BRS characteristics was analyzed. It was observed that the embedded SWCNTs absorb more metal ions and trigger the conductive filament in the chitosan electrolyte, resulting in a more stable and wider BRS window compared to the device with no SWCNTs. The memory window of the chitosan nanocomposite memristors with SWCNTs was 14.98, which was approximately double that of devices without SWCNTs (6.39). Furthermore, the proposed SWCNT-embedded chitosan-based memristors had memristive properties, such as short-term and long-term plasticity via paired-pulse facilitation and spike-timing-dependent plasticity, respectively. In addition, the conductivity modulation was evaluated with 300 synaptic pulses. These findings suggest that memristors featuring SWCNT-embedded chitosan are a promising building block for future artificial synaptic electronics applications.