Use Of Carbon Nanotubes Research Articles

Skepticism regarding the use of carbon nanotubes as reinforcing agent in ceramics for biomedical applications: A critical review

Recent advancements in composite materials, including ceramics, metals, and polymers, have shown significant promise for biomedical applications. In particular, the use of carbon nanotubes (CNTs) as reinforcement in alumina and zirconia ceramics has garnered attention due to their potential to greatly enhance mechanical properties. CNTs, with their high aspect ratio, mechanical strength, and electrical conductivity, offer unique advantages for improving traditional ceramics used in biomedical applications, such as hip and knee replacements, where alumina and zirconia have been employed since the 1970s for their superior wear resistance and biocompatibility. This review critically examines the mechanical benefits of CNT-reinforced ceramics, focusing on factors such as CNT distribution, reinforcement mechanisms, fracture toughness, and long-term durability. Additionally, it explores the significant challenge of CNT toxicity, cytocompatibility, and potential long-term health risks, particularly their non-biodegradable and carcinogenic nature, which could limit their use in medical implants. While promising, inconsistencies in reported improvements, largely due to dispersion issues and ceramic-CNT interactions, along with unresolved toxicity concerns, indicate the need for further research. This review aims to provide a comprehensive understanding of both the mechanical potential and the biological risks of CNT-reinforced ceramics in biomedical applications.

Heat Transfer in Carbon-Nanotube Dispersions: A Simulation Study of the Role of Nanotube Morphology and Connectivity

Simulation of the behavior of carbon nanotubes (CNTs) can become a very challenging task considering their complicated shape and large aspect ratio. This study aims to elucidate the role of CNT shape, length, and connectivity during heat transfer in CNT dispersions through a three-dimensional (3D) simulator. Three characteristic shapes for the CNTs are considered, namely, straight, moderately curved, and strongly curved. The results reveal that the commonly used assumption of viewing CNTs as straight cylinders leads to significant overestimation of the overall medium conductivity. The CNT length has an important effect on the nanofluid conductivity for all types of CNT shapes considered here. In addition, use of CNTs with higher conductivity than a certain value appears to have no further beneficial effect, thus relaxing the need for extremely pure or single-wall CNTs. On the contrary, the conductivity remains a strong function of the CNT concentration and may be even increased upon organization of CNTs into loose clusters. The overall approach and concept can be extended to CNT composites in a straightforward manner.

Unwinding DNA strands by single-walled carbon nanotubes: Molecular docking and MD simulation approach

Despite the growing research into the use of carbon nano-tubes (CNTs) in science and medicine, concerns about their potential toxicity remain insufficiently studied. This study utilizes molecular docking calculations combined by molecular dynamics simulations to investigate the dynamic intricacies of the interaction between single-walled carbon nanotubes (swCNTs) and double-stranded DNA (dsDNA). By examining the influence of swCNT characteristics such as length, radius, and chirality, our findings shed light on the complex interplay that shapes the binding affinity and stability of the dsDNA-swCNT complex. Molecular docking results identify a zigzag swCNT, with a radius of 0.16 Å and a length of 38 Å, as exhibiting the highest binding affinity with dsDNA (−23.9 kcal/mol). Comprehensive analyses, spanning docking results, binding energies, RMSD, radius of gyration, and potential of mean force (PMF) profiles, provide a detailed understanding of the denaturation dynamics. The PMF profiles reveal the thermodynamic feasibility of the DNA-CNT interaction, outlining distinct energy landscapes and barriers: when the selected swCNT binds within the dsDNA groove, the system becomes trapped at the first and second local energy minima, occurring at 1.48 nm and 1.00 nm, respectively. Intramolecular hydrogen bond calculations show a significant reduction, affirming the denaturing effect of swCNTs on DNA. Furthermore, the study reveals a significant reduction in the binding affinity of Ethidium Bromide (EB) to dsDNA following its interaction with swCNT, with a decrease in EB binding to dsDNA of approximately 13.2 %. This research offers valuable insights into the toxic effects of swCNTs on dsDNA, contributing to a rationalization of the cancerous potential of swCNTs.

Cement-Based Composites Containing Carbon Nanofibers and Carbon Nanotubes

Abstract: In cement-based composites, carbon nanotubes (CNTs) and carbon nano fibres (CNFs) can act as crack bridging, delaying the development of nano fractures into microcracks. Recent research on the use of CNTs and CNFs in cement-based composites was reviewed in this paper. Earlier studies have demonstrated that cement-based composites reinforced with CNTs/CNFs have lower porosities and superior mechanical properties to plain cement-based composites. Using CNTs or CNFs in cement-based composites presents challenges due to their low matrix dispersion and weak interfacial contact. Some projected future investigations were indicated. Results: Earlier studies have demonstrated that cement-based composites reinforced with CNTs/CNFs have lower porosities and superior mechanical properties to plain cement-based composites. Using CNTs or CNFs in cement-based composites presents challenges due to their low matrix dispersion and weak interfacial contact . Recommendation: some projected future investigations were indicated.

Electrochemically-Tunable Intersubband Plasmon Absorption in Carbon Nanotube Films

Owing to their unique photophysics and highly tunable electronic properties, carbon nanotubes (CNTs) are promising materials for next-generation electrochromic devices. Here, we present recent work on ionic liquid-gated carbon nanotube devices that show reversible, bistable, and tunable absorption of near-infrared (NIR) radiation. Gating of the CNTs enables reversible changes in the optical transmittance of up to 40% in the wavelength range of 1.7 – 2.2 µm. Additionally, these devices exhibit bistability in an open-circuit configuration that persists for hundreds of seconds. We explore—both experimentally and with numerical modelling—the impact of CNT diameter on the absorption spectrum and the electrochemical properties of the devices. Our results have implications for the use of CNTs in electrochromic, charge storage, and chemical sensing applications.

Innovative Use of Carbon Nanotubes in Electrochemical Sensors for the Analysis of Europium in Samples from the Environment

An adsorptive stripping voltammetric method for the determination of trace europium(III) based on the adsorption of europium(III)−cupferron complex on the multiwall carbon nanotubes/spherical glassy carbon (MWCNTs/SGC) electrode modified with a lead film is presented. The method was optimized with respect to the main electrochemical parameters that affect the voltammetric determination (supporting electrolyte, pH, cupferron concentration, deposition potential and time). The calibration graph is linear from 5 × 10−9 to 5 × 10−7 mol l−1 with a correlation coefficient of 0.9993 for europium for a preconcentration time of 80 s. The detection limit for a preconcentration time of 80 s is as low as 1.3 × 10−9 mol l−1 for europium. To confirm the effectiveness of the developed procedure on the MWCNTs/SGC electrode, tests were also carried out on a glassy carbon electrode to compare the detection limits obtained. The developed procedure was tested for the effect of extraneous substances on the europium signal. The proposed method was successfully applied by studying natural samples and certified reference materials.

Molecular Dynamics Simulation and Experimental Study of Friction and Wear Characteristics of Carbon Nanotube-Reinforced Nitrile Butadiene Rubber

Nitrile butadiene rubber (NBR) and its various composite materials are widely employed as friction materials in mechanical equipment. The use of carbon nanotube (CNT) reinforcement in NBR for improved friction and wear characteristics has become a major research focus. However, the mechanisms underlying the improvement in the friction and wear characteristics of NBR with different CNT contents remain insufficiently elucidated. Therefore, we conducted a combined analysis of NBR reinforced with varying CNT contents through molecular dynamics (MD) simulations and ring–block friction experiments. The aim is to analyze the extent to which CNTs enhance the water-lubricated friction and dry wear properties of NBR and explore the improvement mechanisms through molecular chain characteristics. The results of this study demonstrate that as the mass fraction of CNTs (0%, 1.25%, 2.5%, 5%) increases, the water-lubricated friction coefficient of NBR continuously decreases. Under water-lubricated conditions, CNTs improve the water storage capacity of the NBR surface and enhance lubrication efficiency. In the dry wear state, CNTs help reduce scratch depth and dry wear volume.

Catalytic methane decomposition on CNT-supported Fe-catalysts

Methane, either as natural gas or as a resource obtained from various bioprocesses (e.g., digestion, landfill) can be converted to carbon and hydrogen according to.CH4(g)→C(s)+2H2(g)ΔH298K=74.8kJ/mol.Previous research has stressed the growing importance of substituting the high-temperature Steam Methane Reforming (SMR) by a moderate temperature Catalytic Methane Decomposition (CMD). The carbon formed is moreover of nanotube nature, in high industrial demand.To avoid the use of an inert support for the active catalyst species, e.g., Al2O3 for Fe, leading to a progressive contamination of the catalyst by support debris and coking of the catalyst, the present research investigates the use of carbon nanotubes (CNTs) as Fe-support.Average CH4 conversions of 75–85% are obtained at 700 °C for a continuous operation of 40 h. The produced CNT from the methane conversion can be continuously removed from the catalyst bed by carry-over due to its bulk density difference (∼120 kg/m3) with the catalyst itself (∼1500 kg/m3). CNT properties are fully specified. No thermal regeneration of the catalyst is required.A tentative process layout and economic analysis demonstrate the scalability of the process and the very competitive production costs of H2 and CNT.

Adsorption and separation of lead ions in phosphoric acid by co-doped carbon nanotubes with sulfur, oxygen, and manganese

The purpose of this study was to prepare a novel and efficient adsorbent for the removal of trace Pb(II) from phosphoric acid. Manganese oxide/sulfur-oxygen doped carbon nanotube composites (CNTs-S-O-Mn) were prepared from multi-walled carbon nanotubes modified with nitric acid, mercaptoacetic acid, acetic anhydride, concentrated sulfuric acid and potassium permanganate. Characterisation revealed that CNTs-S-O-Mn contained hydroxyl, sulphonate groups, MnO and Mn3O4. At 298 K, 15.362 mg·L-1 initial concentration of lead ions, and 18.4 % phosphoric acid concentration, the adsorption capacity of the composites for lead ions was 38.65 mg·g−1, which was higher than that of the unmodified CNTs, 8.04 mg·g−1. The adsorption kinetic data at 298 K conformed to the quasi-second-order kinetic equation, R2 = 0.997; 298, adsorption isotherms at 308 and 318 K conformed to the Langmuir equation, R2 = 0.990–––0.991. The adsorption capacity increased with decreasing phosphoric acid concentration. In this system, the adsorption is affected by a certain concentration of lead ions. Adsorption occurs via chemisorption and is exothermic. Sulfonic acid groups and hydroxyl groups on manganese oxides play an important role in the adsorption of Pb (II) through surface complexation with Pb (II). These results indicate that the removal of trace Pb (II) from phosphoric acid by modified carbon nanotubes is feasible, revealing a new use of carbon nanotubes for phosphoric acid purification.

Resistance Welding of CF/PEI Composites by a Novel Implant of Flame-grown Carbon Nanotubes Grafted Carbon Fibers

Objective: Interface enhancement between resin and fiber has been a longstanding goal for manufacturing composite material. Using carbon nanomaterials in combination with macro-materials for composite materials is an important application of advanced manufacturing technology. Methods: This study examined the use of carbon nanotubes (CNTs) wrapped carbon fibers (CFs) (CFs@CNT), a cross-scale composite component incorporating CNTs and CFs, as an implant for resistance welding of composites containing carbon-fiber-reinforced polyetherimide (CF/PEI). Results: The correlation of growth time (tg) on growth morphology of CNTs on implant and strengths of joints were studied. The surface of CF was gradually covered by CNTs and finally completely wrapped, and CNTs appeared as multi-walled CNTs. The interface structure of resistance welded joints and their mechanical properties were evaluated. The PEI resin was sufficiently melted and obtained a perfect bonding joint with stronger mechanical properties when tg was 2min and 3min. The cracks were found at the edge of the bonding interface and a collapse first appeared in joint when tg was 4min and 5min, respectively. The defects were caused by the accumulation of amorphous carbon at the top of the CNTs. The strength of joint welded by CFs@CNT implant increased to 37.8MPa compared with the joint obtained by pure CFs implant alone only 24.2MPa when tg was 3min. Conclusion: The purpose of strengthening the joint was achieved by improving the wettability of PEI resin on CFs@CNT lead to the CFs was fully wrapped by molten resin during welding process.

Carbon nanotubes: a novel innovation as food supplements and biosensing for food safety.

Recently, nanotechnology has emerged as an extensively growing field. Several important fabricated products including Carbon nanotubes (CNTs) are of great importance and hold significance in several industrial sectors, mainly food industry. Recent developments have come up with methodologies for the prevention of health complications like lack of adequate nutrition in our diet. This review delves deeper into the details of the food supplementation techniques and how CNTs function in this regard. This review includes the challenges in using CNTs for food applications and their future prospects in the industry. Food shortage has become a global issue and limiting food resources put an additional burden on the farmers for growing crops. Apart from quantity, quality should also be taken into consideration and new ways should be developed for increasing nutritional value of food items. Food supplementation has several complications due to the biologically active compounds and reaction in the in vivo environment, CNTs can play a crucial role in countering this problem through the supplementation of food by various processes including; nanoencapsulation and nanobiofortification thus stimulating crop growth and seed germination rates. CNTs also hold a key position in biosensing and diagnostic application for either the quality control of the food supplements or the detection of contagions like toxins, chemicals, dyes, pesticides, pathogens, additives, and preservatives. Detection such pathogens can help in attaining global food security goal and better production and provision of food resources. The data used in the current review was collected up to date as of March 31, 2024 and contains the best of our knowledge. Data collection was performed from various reliable and authentic literatures comprising PubMed database, Springer Link, Scopus, Wiley Online, Web of Science, ScienceDirect, and Google Scholar. Research related to commercially available CNTs has been added for the readers seeking additional information on the use of CNTs in various economic sectors.

Use of carbon nanotubes in flat and evacuated tube solar collectors for thermal enhancement: A review

Solar thermal collectors (STCs) are a potential heating and cooling solution owing to their pollution-free nature and availability in many parts of the globe. Enhancing the thermal efficiency of STCs is crucial for optimizing energy conversion. In this respect, the purpose of this article is to provide an overview of the usage of carbon nanotubes (CNTs) for the enhancement of thermal performance in evacuated tube and flat plate solar thermal collectors. According to the research that was conducted earlier, it was discovered that the use of CNTs, both single-walled and multi-walled, results to increases the efficiency of a flat and evacuated solar thermal collector. In this article, the impact of carbon nanotubes (CNTs) was investigated in depth for their potential usage in flat and evacuated tube solar collectors (ETSCs). This review article offers a novel aspect based on extensive research that has been published in the past related to the impact of CNTs on the thermal performance of flat and ESTCs.

Molecular dynamics study of the interface fine structure and mechanical properties of Ni@SWCNT/Cu nanocrystalline composite materials

The use of carbon nanotubes (CNTs) as reinforcing phase in copper-based composites has been extensively studied. However, controlling the synthesis interface structure and explaining the nanoscale interface bonding mechanism through experimental methods still poses challenges. In this study, a model of single-walled carbon nanotube nanocrystalline copper composite was established based on molecular dynamics (MD) simulations to investigate the effects of grain boundaries and dislocations on the composite material. It was found that the addition of nickel atoms improved the interface bonding between carbon nanotubes and the copper matrix, reducing vacancies at the interface. Ni@SWCNT/Cu exhibited better mechanical properties. Structural changes and defect evolution during deformation were studied. The ultimate tensile strength of SWCNT/Cu and Ni@SWCNT/Cu composites increased by 62.29 % and 68.78 % respectively compared to nanocrystalline copper, while the Young's modulus increased by 25.91 % and 32.48 % respectively; moreover, the Young's modulus of these two composites increased by 45.24 % and 49.42 % respectively. Ni@SWCNT/Cu had the lowest wear rate and friction coefficient, with a minimum wear rate of 0.0055 and a minimum friction coefficient of 0.67, demonstrating better wear resistance. The effects of different friction speeds and depths of indentation on the friction performance of the composite materials were also investigated.

Application of CNTs/H2O nanofluid and the wavy fin with dimples in thermal management of CPU: A numerical modeling of hybrid passive cooling

A study was conducted utilizing computational fluid dynamics (CFD) to explore a novel cooling technique for the central processing unit (CPU), involving the use of carbon nanotubes (CNTs)/H2O nanofluid-fin heat sinks with dimples. Different fin heat sink designs with varying dimple arrangements were created using AutoCAD software. The three-dimensional flow, heat transfer, and mass transfer of the nanofluid within the liquid block were simulated using a finite volume-based CFD code. The study investigated the influence of different nanoparticle concentrations and dimple arrangements on cooling performance, heat transfer coefficient, pumping power, and thermal efficiency. The results revealed that the maximum temperature reduction on the CPU's top surface was approximately 13.1 K for multi-walled carbon nanotube/H2O nanofluids and 14.34 K for single-walled carbon nanotube (SWCNT)/H2O nanofluids. The best thermal efficiencies were achieved using SWCNT (2%)/H2O with three rows of dimples on each fin, resulting in an 8.5% improvement in heat sink performance at Re = 1,500 and an 8.8% improvement at Re = 2,000 compared to fins without dimples. However, it was observed that increasing the number of dimples on the fins led to an increase in pressure drop within the liquid block, necessitating additional pumping power. The simulation results aligned well with earlier experimental data and numerical studies in terms of cooling and heat transfer.

Magnetized hybrid nanofluid flow across a wedge: A computational three-dimensional study

The boundary layer fluid flow past a wedge surface occurs in various industrial processes, including wire drawing, metal foaming, polymer extraction, fiber processing, and in determining the dynamic properties (shear stress, drag) of working fluids. Theoretically, the boundary layer three-dimensional flow of a magnetized hybrid nanoliquid over a wedge surface is studied with viscous dissipation and radiation effects. The flow is due to moving wedge surface and power-law free-stream velocities. The current study unifies three different classical flow problems, namely, the Blasius flow, the Hiemenz flow, and the Falkner-Skan flow. Single-phase description of hybrid nanofluid is considered, and the problem is kept realistic by considering the experimental thermophysical properties of the nanomaterial. The governing system consists of conservation of mass, momentum, and the energy equations for hybrid nanofluids. Prandtl’s boundary layer approximations are applied to study the viscous dominant fluid regimes. The entropy equation and the Bejan number are also derived. Numerical computations of self-similar equations are obtained to explore the rheological and the heat transport features against the physical parameters. The Nusselt number and the drag on the wedge surface are computed and analyzed. Of the three classical flow problems, the maximum thickness of the momentum layer occurs for the Blasius flow problem. A minimum drag force on the wedge surface occurs for lower Hartmann number values. Furthermore, an increase in the volume fraction of the hybrid nanoparticles leads to an enhanced heat transport. The use of carbon nanotubes which has exceptional characteristics are taken into consideration in this study. This study also demonstrates the comparison on three-different classical flow problems (Blasius flow, Hiemenz flow, and Falkner-Skan flow).

CNT thin films based on epoxy mixtures: fabrication, electrical characteristics

The simple scaling of silicon transistors no longer ensures the advantages of high energy efficiency, driving research into nanotechnologies beyond silicon. Specifically, digital circuits based on carbon nanotube (CNT) field-effect transistors promise significant advantages in energy efficiency. However, the inability to perfectly control internal nanoscale defects and the variability of carbon nanotubes hinder the realization of very large-scale integrated systems. In this study, we investigated a novel method for fabricating transistors based on carbon nanotubes (CNTs) using epoxy mixtures, obtained the electrical properties of the transistors, and compared their microstructure and composition via the scanning electron microscopy. The carrier mobility on epoxy-based transistors was 28.87 cm²/V∙s, and the transistor switching frequency was 2.2 MHz. The samples exhibited electrical and physical stability over an extended period of time. The use of carbon nanotubes in epoxy resin as a conducting layer for transistors opens significant prospects in the field of electronics. The CNT-epoxy mixture technology allows for more flexible and rapid fabrication of thin-film transistors compared to classical methods. However, it is not appropriate to speak of a complete replacement; in this study, we present an alternative method for producing thin-film transistors, which may be of interest for specific purposes.

Inherent resonance of carbon and graphene-based nanocomposite coupled single-span arch beams

In recent decades, there has been a significant rise in the utilization of composite materials for various engineering applications. These advanced materials offer the potential to improve the mechanical properties and vibration characteristics of structural components. This particular study is dedicated to enhancing the vibration performance of coupled curved-curved beams that feature a linear elastic mid-layer, achieved through the incorporation of carbon nanotubes (CNTs), graphene nanoplates (GNPs), and graphene oxide powder (GOPs). The governing equations of the system are solved using the generalized differential quadrature (GDQ) method. While previous research primarily focused on the use of CNTs to enhance the vibration behavior of coupled-curved beams, this study delves into the utilization of multiple nanofillers for this purpose. An essential aspect of modeling composite materials lies in determining their equivalent mechanical properties. This research undertakes a comparison between the rule of mixture (RoM) and Halpin-Tsai methods for calculating these properties, revealing that frequencies derived from the RoM method are higher than those obtained through the Halpin-Tsai approach. Additionally, the study highlights that systems incorporating GNPs demonstrate higher frequencies at lower nanofiller volumes, with CNTs and GOPs following in ranking. However, this hierarchy shifts at higher nanofiller volumes. The arrangement of nanofillers within the system is influenced by its boundary conditions, with the curvature of the bottom beam playing a significant role in affecting vibration behavior. Increasing the radius of the bottom beam (R2) leads to higher system frequencies, which subsequently decrease with higher R2 values.

Jute and Flax Fiber Composites Enhancement through Carbon Nanotube Filler

This investigation primarily focuses on enhancing the sustainable jute/flax/epoxy nanocomposite with the use of carbon nanotubes (CNTs) as filler. The flax and jute natural fibres were treated with sodium hydroxide solution. The compression moulding technique was preferred for better fabrication. The CNTs were thoroughly mixed with epoxy resin with the help of a ball milling-type mixture. The nanocomposite samples were prepared by varying the reinforcement and filler content. Jute fibre varied from 59 to 99 wt%, Flax Fiber varied from 0 to 40 wt% and the filler was maintained as constant of 1 wt%. The five types of laminated and fabricated composites were characterized in terms of tensile strength, flexural strength and modulus of elasticity. The SEM examinations were carried for the composite samples to analyse the fibre diameter (µm), CNT dispersion and interfacial adhesion. The results revealed that the sample fabricated with 69 jute fibre, 30 wt% flax fibre, and 1 wt% CNT filler outperformed with 60.1 MPa tensile strength, 79.3 MPa flexural strength, 8.1 GPa modulus of elasticity.

On the Darcy–Forchheimer flow of carbon nanotubes nanofluid across a stretching surface for the impact of heat source/sink and Ohmic heating

This research leads to carrying out the productivity and the efficiency of the carbon nanotubes (CNTs) that have extensive applications in solar collectors. Due to the superior thermal as well as electrical properties, the use of CNTs has an important contribution to the nanotechnology revolution. Therefore, owing to the aforementioned vital points, this investigation intended to put forth the thermophysical properties of both single and multi-walled CNT nanofluids past a stretching surface. Additionally, an electrically conducting nanofluid flow phenomenon enriches due to the inclusion of dissipation (Ohmic heating) and external heat source/sink. The dimensional form of the three-dimensional fluid flow phenomena is transformed to a non-dimensional form with the use of similarity transformation and further numerical procedure is implemented to solve the nonlinear governing equations. The substantial significance of the characterizing parameters is presented briefly via figures and the comparative analysis with the earlier investigation is deployed through the table. However, the main findings of this study are as follows: A significant attenuation in the shear rate is marked for the enhanced inertial drag but it augments for the augmented values of the magnetization; further, particle concentrations of both the CNTs favor accelerating the fluid momentum as well as temperature distribution.

The importance of carbon nanoenergy oil-producing countries

The importance of carbon nanoenergy for oil-producing countries, including traditional hydrocarbon energy, the use of carbon nanotubes, and gas hydrate energy, is considered. It is shown that the features of all types of carbon materials are determined at the nanoscale and that modern energy criteria determine the development of nanoenergy as one of the most important areas of nanotechnology application in the global economy. Carbon is used in equipment elements of renewable energy sources, in the nuclear industry, in hydrogen and solar energy. The renewable nature of hydrocarbon resources due to the carbon cycle is noted.