Performance Of Carbon Nanotubes Research Articles

Enhancing Long-Term Memory in Carbon-Nanotube-Based Optoelectronic Synaptic Devices for Neuromorphic Computing.

This study investigates the impact of spin-coating speed on the performance of carbon nanotube (CNT)-based optoelectronic synaptic devices, focusing on their long-term memory properties. CNT films fabricated at lower spin speeds exhibited a greater thickness and density compared to those at higher speeds. These denser films showed enhanced persistent photoconductivity, resulting in higher excitatory postsynaptic currents (EPSCs) and the prolonged retention of memory states after UV stimulation. Devices coated at a lower spin-coating speed of 2000 RPM maintained EPSCs above 70% for 3600 s, outperforming their higher-speed counterparts in long-term memory retention. Additionally, the study demonstrated that the learning efficiency improved with repeated UV stimulation, with fewer pulses needed to achieve the maximum EPSC in successive learning cycles. These findings highlight that optimizing spin-coating speeds can significantly enhance the performance of CNT-based synaptic devices, making them suitable for applications in neuromorphic computing and artificial neural networks requiring robust memory retention and efficient learning.

A Comparative study of flow and C[sbnd]C heat flux over a magnetic field under the influence of nanomaterial and carbon nanotubes

The aim of this study is to investigate convective heat transfer on a flat surface in the presence of magneto-hydro-dynamic (MHD) flow. The analysis considers the Darcy-Forchheimer porosity medium in the flow. The study focuses on analyzing the heat transfer rate, incorporating joule heating and convective-conductive heat flux effects. The influence of varying fluid properties on the flow behavior is examined. The governing flow equations are initially expressed as partial differential equations (PDEs) and then transformed into ordinary differential equations (ODEs) using appropriate similarity transformations. The numerical method RKF-45 is employed to solve these ODEs. The results highlight the impact of different parameters in the model. It is observed that a higher Darcy parameter leads to a decrease in fluid velocity. Additionally, the performance of carbon nanotubes is superior compared to MoS2 nanoparticles in this study.

Expression of Concern: The Molecular Dynamics Study of Vacancy Defect Influence on Carbon Nanotube Performance as Drug Delivery System

Expression of Concern: The Molecular Dynamics Study of Vacancy Defect Influence on Carbon Nanotube Performance as Drug Delivery System

Electrostatic self-assembly effect of Fe3O4 nanoparticles on performance of carbon nanotubes in cement-based materials

Abstract The beneficial effect of carbon nanotubes (CNTs) to enhance the electrical conductivity and piezoresistivity of cement-based materials was highly contingent upon its dispersion. To achieve an appropriate dispersion of CNTs, ultrasonication, high-speed stirring, and chemical dispersion were commonly used, which raises the risk of structural damage of CNTs caused by the excessive energy. In this study, electrostatic self-assembly of Fe3O4 nanoparticles on CNTs was employed to efficiently disperse CNTs. To optimize the dispersion effect of conductive fillers in cement paste, the mix proportions including sodium dodecyl sulfate (SDS) concentration, CNTs concentration, and Fe3O4/CNTs ratios were adjusted. The dispersion degree and electrical property were evaluated by UV–vis absorption and zeta potential. In addition, the effect of self-assembled conductive filler dosage on the electrically conductive property of cement pastes was examined. The results show that the occurrence of electrostatic self-assembly was proved by the change of zeta potential, and the grape-bunch structure was observed by transmission electron microscopy. Further, the optimal proportions of self-assembled conductive fillers were 0.20 wt% SDS concentration, 0.05 wt% CNTs concentration, and 1:1 Fe3O4/CNTs ratio. The self-assembled conductive filler dosage between 0.02 and 0.10 wt% can effectively improve the electrical conductivity of cement paste with up to 68% reduction of resistivity.

Performance of Carbon Nanotube on Nickel-Plated Copper Substrate Using Electrophoretic Deposition Process for Electronic Cooling Application: Response Surface Method Optimization

Performance of Carbon Nanotube on Nickel-Plated Copper Substrate Using Electrophoretic Deposition Process for Electronic Cooling Application: Response Surface Method Optimization

Performance of carbon nanotubes (CNTs) on the development of radiating hybrid nanofluid flow through an stretching cylinder

In various industries, one of the important aspects is the cooling processes for which the material exhibits its perfect shape and size. Intending to the aforementioned property the current investigation leads to carry out the features of the materialistic property of thermal radiation and the dissipative heat by incorporating these in the water-based hybrid nanofluid. The fluid past a stretching cylinder embedded with a permeable medium and the impact of the magnetic field, and thermal radiation are depicted in momentum and energy profiles. In addition to that, the role of the Hamilton-Crosser conductivity model for the behavior of various shapes of the carbon nanotube (CNT) nanoparticles with their volume concentration is also vital. The transformation of the dimensional form of the governing equations into the non-dimensional form is obtained with the use of proper transformation rules. Further, the proposed designed model is handled by employing the traditional shooting-based Runge-Kutta fourth-order technique. The significant properties of different components are deployed graphically and the validation with earlier study shows a good correlation. Moreover, the important characteristics of the outcomes are; the surface cooling, driven by increased thermal buoyancy, promotes fluid velocity while simultaneously influencing the curvature parameter and profile to slow down the accumulation of nanoparticles.

Ni and Fe mixed oxide anchored on CNTs, GONRs, and Ti3C2 Mxene as efficient nanocatalysts for direct power generation from methanol electro-oxidation

In the field of heterogeneous catalysis, the selection of appropriate support is an effective strategy due to metal loading reduction and enhancing electron transfer kinetic. In this work, the performance of carbon nanotubes (CNTs), reduced graphene oxide nanoribbons (rGONRs), and titanium carbide nanosheets (Ti3C2 Mxene) as support was investigated on the catalytic performance of NiFe2O4 spinel nanoparticles. The samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, BET surface area analysis, field emission scanning, and transmission electron microscopy. The electrochemical properties of samples as fuel cell catalysts were compared using electrochemical techniques. The electrocatalytic activity of samples in methanol oxidation reaction (MOR) was obtained to be: NiFe2O4/Ti3C2> NiFe2O4/rGONRs > NiFe2O4/CNTs > NiFe2O4. The results approve that the Ti3C2 Mxene promotes the catalytic performance of NiFe2O4 and enhances the methanol oxidation kinetics via conductive pathway creation. Therefore, Ti3C2 can lead to great opportunities as an efficient catalyst support for alcohol fuel cells in the future.

Preparation of carbon nanotubes with high filling rate of copper nanoparticles

Performance of carbon nanotubes (CNTs) can be adjusted by filling their cavities with guest materials. In this study, Cu nanoparticles are filled into CNTs via wet chemical method. To improve the filling efficiency, oxygen-containing functional groups (OCFGs) are introduced onto the tube walls of CNTs by acid treatment. The defects and pore size distribution on CNTs are detected and quantified by N2 adsorption-desorption experiment, Raman spectra, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Morphologies of CNTs before and after filling treatment are observed by transmission electron microscope (TEM). The filling rate is characterized by inductively coupled plasma emission spectrometer (ICP) and thermal gravimetric analysis (TGA). The results indicate that the OCFGs can not only improve the hydrophilicity of CNTs, but also greatly affect the filling rate of CNTs. The filling rate of CNTs acid-treated for 24 h (1.99 wt% tested by TGA) is significantly lower than that of acid-treated for 8 h (12.11 wt% tested by TGA), which can be ascribed to the fact that excessive OCFGs could hinder Cu2+ ions from entering the cavity of CNTs. The obtained results can provide a new perspective for the application of CNTs in composite preparation and related fields.

The molecular dynamics study of vacancy defect influence on carbon nanotube performance as drug delivery system

In the current research, we described atomic vacancy defect influence on nanopumping performance of CNT structure with molecular dynamics (MD) method (for the first time). In our simulations, CNT structure is defined in the presence of C20 molecule and Au tips in the nanopumping process. Temperature and potential energy convergence after 1 ns indicated the atomic stability in defined systems, which this result arises from the appropriate settings inside the MD box. Also, the nanopumping process was detected after 0.26 ps for the CNT structure without any vacancy defect. By atomic defect implementation to C-based nanotube, the nano-pumping performance of this tube was disrupted. Numerically, by inserting 1% vacancy to pristine CNT, the nanopumping was detected after 0.29 ps. Furthermore, MD outputs predicted by implementing vacancy defect with a larger 10% ratio, nanopumping process doesn't occur. On the other hand, by nanopumping parameters optimization in defected CNT (with 1% defect), this atomic process (nanopumping) occurs after 0.24 ps.

The effect of thickness on the multiwalled carbon nanotubes performance in glass/epoxy composite laminates under dynamic loading

AbstractThe aim of this research is to investigate the thickness influence on the efficiency of multiwalled carbon nanotubes (MWCNTs) in glass/epoxy composite laminates under the high‐velocity impact. Combining 0.25 wt% of MWCNTs in the 4‐layer and 8‐layer specimens and 0.1 wt% of MWCNTs in the 16‐layer specimen led to the maximum rise in the energy absorption and specific perforation energy compared with the unreinforced laminates. The significant growth in energy absorption in the 4‐layer, 8‐layer, and 16‐layer specimens was 5.8, 8.3, and 14.4 J, respectively. The number of agglomerations (dislocations) in the matrix was consequently increased as a function of thickness, which led to the better performance of MWCNTs with lower weight percentages in the composite laminates containing more layers. The scanning electron microscope was used to observe the dispersion and agglomeration of MWCNTs in the resin epoxy, and there was also an improvement in the fiber–resin bonding.

CNT/epoxy interleaves for strengthening performance of filament wound composite structures

The failure mechanism of composites dominates the matrix, fiber and interface, and in general, the matrix corresponds to the definitive cause of damage. A filament–wound composite structure involves a notable bridging effect owing to the matrix between the layers, and particle additives are generally adopted to strengthen the matrix. However, particle additives exhibit a low performance when applied to structures, owing to the dispersibility and particle agglomeration. In this study, the strengthening performance of carbon nanotube (CNT)/epoxy interleaves was experimentally verified to facilitate their implementation in the structural design of a filament–wound cylinder structure. The burst pressure, compression, bending and interfacial bonding strength of the cylinder improved by approximately 20%, 161%, 16% and 36%, respectively, and the positioning of CNT/epoxy interleaves was a more notable influencing factor compared to the proportion of CNTs in the entire winding layer. The number of macro voids decreased inside the epoxy modified CNT. The findings demonstrated that the incorporation of CNTs through CNT/epoxy interleaves could facilitate the matrix strengthening and enhance the interfacial bonding.

Preparation of NH2-SH-GO/SWCNTs based on graphene oxide/single-walled carbon nanotubes for CO2 and N2 separation from blast furnace gas

The traditional molecular sieve membrane for gas separation is mostly prepared by zeolite, MOFs and other materials. Nano-carbon materials such as graphene and carbon nanotubes have been studied in the field of gas separation in recent years which have large specific surface area and high porosity. The performance of carbon nanotubes and graphene can be effectively improved by adding corresponding groups. A novel molecular sieve membrane was synthesized by sulfhydryl and amino-modified graphene oxide/oxidized single-walled carbon nanotubes (NH 2 -SH-GO/SWCNTs). The composite material was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller specific surface area analyzers. The results reveal that laminated graphene oxide and tubular single-walled carbon nanotubes are intertwined and carbon nanotubes attach onto the surface of GO or intercalate into the GO sheets to form a spatial stereoscopic structure. TGA results demonstrate that the loading amount of amino and sulfydryl groups in NH 2 -SH-GO/SWCNTs is about 11.91 wt%. When the intake pressure of N 2 is 0.10 MPa, the permeability coefficient for N 2 passing through NH 2 -SH-GO/SWCNTs is 1829 Barrer. With the increase of temperature, permeability coefficient for N 2 decreases, while it increases as the intake pressure rises. The experimental results for mixed gases passing through NH 2 -SH-GO/SWCNTs show that, when P 0 = 0.10 MPa and T = 323 K, the permeability coefficient for CO 2 is 1896 Barrer, while that for CO is only 116 Barrer. At 323 K, selectivity for N 2 /CO, CO 2 /CO and CO 2 /N 2 is 39.2, 46.3, and 9.3, respectively. These results indicate that NH 2 -SH-GO/SWCNTs may be a promising molecular sieve membrane for gas separation. • Simultaneously separate CO 2 and N 2 from blast furnace gas. • Preparation of new style NH 2 -SH-GO/SWCNTs. • The permeability coefficient for N 2 is 1829 Barrer. • Selectivity for N 2 /CO, CO 2 /CO and CO 2 /N 2 is 39.2, 46.3, and 9.3, respectively.

Nitrogen functionalized carbon nanotubes as a support of platinum electrocatalysts for performance improvement of ORR using fuel cell cathodic half-cell

In many works of literatures, the performance of carbon nanotubes as Pt support has been studied in the oxygen reduction reaction (ORR). Here we demonstrate the impact of these carbon nanotubes after modification by nitrogen groups to improve the performance of ORR in PEM fuel cell applications. In this regard, the characterization results of bare (MWCNTs), and functional groups of nitrogen by triethylenetetramine (MWCNTs-TETA), diethylenetriamine (MWCNTs-DETA) and malononitrile (MWCNTs-MN)precursor were presented and then the electrochemical analysis of Pt nanoparticles depositing on them are studied. The role of nitrogen functional groups on the activity and stability of Pt nanoparticles is investigated. These parameters are investigated using catalyst coated membrane electrode (CCME) which is placed inside a homemade cathodic half-cell. The CCME is prepared with a Nafion 117 membrane and gas diffusion layer (GDL) having an active area of 0.785 cm2. The half-cell test results show that Pt/MWCNTs-TETA electrode had the highest ORR performance of 64.48 mW cm−2, while showed the lower ECSA drop than Pt/MWCNTs.

Effect of ‘water-in-salt’ electrolytes in the electrochemical hydrogen evolution reaction of carbon nanotubes

Super-concentrated electrolytes based electrochemistry is an emerging trend in electrochemical processes (Borodin et al 2020 Joule 4 69–100), where unprecedented properties were reported recently. Such an ‘electrolyte engineered approach’ can find applicabilities in modern batteries and catalysis. Here we report the use of such high concentration lithium ions (Li+) containing electrolytes for enhancing the electrocatalytic hydrogen evolution (HER) performance of carbon nanotubes (CNTs), contrary to that observed with platinum. Different types of CNTs, namely metallic multi-wall (MWCNTs) and semiconducting single wall (SWCNTs), are tested towards the Li+ effect in the HER performance and similar trends are obtained. Further, different lithium salts having counter ions such as TFSI−, OTf−, ClO4−, Cl−, and OH− are also tested to verify the mechanism, and the role of Li+ in the HER augmentation of CNTs is established. The studies are conducted in different electrolytes having a range of pH values too (0–13), and the cation induced CNT’s HER enhancement is generalized. This study shows that even the sluggish HER kinetics of CNTs in alkaline medium can be augmented by such an electrolyte engineering approach where catalyst’s surface do not undergo any permanent modification. Further, such electrodes are found to be highly stable towards the long term HER performance.

Improved Thermoelectric Behavior of Super-Growth Carbon Nanotube Using Tetrathiafulvalene-Tetracyanoquinodimethane Nanoparticles

The addition of inorganic materials with high thermoelectric properties is a popular approach to modulate the performance of carbon nanotube (CNT), but, the representative hybridization of CNT and toxic Te or Bi is not practical considering safety. Here, we report a CNT film including charge-transfer complex nanoparticles, which has higher generality and thermoelectric properties. Interestingly, the CNT film containing 30 wt% Tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) nanoparticle exhibited a higher in-plane thermoelectric power factor (44.3 μW m-1 K-2) than the pure CNT (10.1 μW m-1 K-2), which is the first result of a nanostructured charge-transfer complex acting as a carrier promoter.

Exploring the Impact of Counterion Chemistry on Carrier Doping of Carbon Nanotubes

Semiconducting single-walled carbon nanotubes (s-SWCNT) are viewed as a promising candidate for optical, electronic, and energy conversion applications. Often the performance of carbon nanotubes in these applications is dependent on being able to control the interplay between their optical and electronic properties. One strategy toward achieving this control is tuning the position of the Fermi level through chemical doping to inject charge carriers into the electronic density of states.We have previously demonstrated that p-type doping using the one-electron oxidant, triethyloxonium hexachloroantimonate (OA) results in very efficient injection of free carriers into near-monochiral s-SWCNT networks. Here we build on our previous work by employing a series of charge-transfer dopants based on boron clusters appended with various organic moieties that control the redox properties of the dopant. These dopants are unique, since their chemical structure means that the electron that is extracted from the nanotube is localized on the boron cluster and spatially separated from hole density injected into the carbon nanotube. We explore the charge-transfer doping process using these boron-cluster dopants, the resulting charge-carrier transport properties of the doped s-SWCNT networks, and make a comparison to networks doped using either OA or 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ). We will present spectroscopic and bulk conductivity measurements of charge-transport in high-mobility s-SWCNT networks and will discuss the impact that the chemistry and structure of the dopant counterion has on charge transport and the implications for electronic devices comprised of these tailored s-SWCNT networks.

Numerical Investigation for Convective Heat Transfer of CNT Nano-Fluids over a Stretching Surface

The performance of carbon nanotube (CNT) nanofluids on convective heat transfer over a stretching sheet was investigated under thermal stratification and magnetic field effects. Water, engine oil and ethylene glycol are used as the base fluids. The governing equations are transformed into a system of coupled nonlinear ordinary differential equations using similarity transformations and solved numerically using the fourth-order Runge–Kutta–Fehlberg in conjunction to shooting method. The CNT nanofluids with an engine oil base fluid shows the highest thermal conductivity in comparison to ethylene glycol and water, respectively. Potential application of the thermal conductivity enhancement of CNT nanofluid is to increase the energy-efficient mechanical systems in heating, cooling and ventilation of the indoor environment.

Effect of Carbon Nano Tube on performance of asphalt binder under creep-recovery and sustained loading conditions

Abstract The present study aimed at evaluating the rutting performance of Carbon Nano Tube (CNT) modified asphalt binder under different loading conditions. CNT content was varied as 0%, 0.4%, 0.75%, 1.5% and 2.25% by the weight of control binder. Superpave rutting parameter (G*/Sinδ) and Shenoy parameter (G*/(1-(1/TanδSinδ))) were initially evaluated using temperature sweep test. Though both parameters showed a similar trend, the later one found to have more sensitivity towards evaluating unrecoverable strain value. Creep-recovery test was further conducted at four different stress levels (100 Pa, 3200 Pa, 5000 Pa, and 10000 Pa) to understand the effect of CNT under cyclic loading-unloading condition. Improvement in recovery value and a corresponding decrease in non-recoverable creep compliance value was observed with the addition of CNT. Further attempt was made to model the strain response from creep-recovery test using the Burgers model and Power model. Based upon the variation of viscous component of steady flow obtained from the Burgers model, CNT addition found to improve the rutting performance. Further, the power model also showed an excellent prediction of strain response under creep period, however, deviation from the experimentally observed response was observed in the recovery period. Modification to the power law model was done which significantly improved the strain prediction in the recovery period. Likewise, the effects of CNT under sustained loading condition was evaluated using a creep test at two different stress levels (100 Pa and 3200 Pa). Incremental dosages of CNT shifted the binder response from linear to nonlinear viscoelastic region at comparatively lower creep period. Significant decrease in deformation rate was also observed with CNT addition.

(Invited) Controlling Energy Transport in Tailored Carbon Nanotubes Networks for Energy Harvesting Applications

The ability to selectively extract semiconducting single-walled carbon nanotube (s-SWCNT) species from the raw material with high fidelity is leading to their incorporation as elements in a variety of optical and electronic applications. We have recently employed conjugated polymers based on the fluorene chemical moiety to produce tailored s-SWCNT samples that can be incorporated into photovoltaic, thermoelectric, and transistor architectures.By controlling both the extent of carbon nanotube bundling and/or removing the insulating polymer that wraps the individual carbon nanotubes, we explore the complex effects of these morphological modifications on the transport of energy by excitonic species and charge carriers in enriched s-SWCNT networks. We show that removal of the insulating polymer, which is often strongly bound to the carbon nanotubes through van de Waals forces between the π-electron systems of the two components, results in a significant improvement in charge carrier transport. In contrast, exciton transport is subtly dependent on the specific nanotube-nanotube interactions in the network. For instance, exciton energy transfer to minority low-bandgap species within a bundle is extremely efficient, but this often traps the exciton in an individual bundle, thereby inhibiting long-range transport within the network.As alluded to above, the performance of carbon nanotubes in these applications is sometimes strongly dependent on the interplay between the optical and electronic properties of the s-SWCNT networks, which can be controlled by tuning the charge carrier density. We have developed a number of processes that allow us to exert fine control over the charge carrier density injected by redox-active chemical dopants, including the ability to controllably dope the s-SWCNT network p-type and n-type. We will discuss how these strategies can be exploited to exert fine control over charge-carrier transport in the doped s-SWCNT networks, allowing us to target the optimum doping level for the desired application.Finally, we will discuss the implications of our findings within the context of the incorporation of enriched s-SWCNT networks in energy harvesting applications.

Friction reducing performance of carbon nanotubes covered pistons in internal combustion engines – engine test results

This article discusses the posibility of reducing friction losses in internal combustion engines by using carbon nanotubes, pointing out the large potential of this application. Experimental pistons were made of standard aluminum alloy and coated with a layer of nanotube deposits by spraying them with an aqueous solution containing the binder. The proposed technology of applying layers of nanotubes can be adopted in industrial-scale production. Engine tests were carried out showing a significant reduction of the engine motoring torque, up to 16% for the experimental pistons, thus confirming the favorable tribological properties of nanotubes observed in tribological research and reported by many authors. Supplementary tests were carried out: SEM, EDS, coordinate measuring technique, and x-ray tomography. An alternative technology for hierarchical nanotube multilayer coatings electro-deposition was proposed.