Fabrication Of Carbon Nanotubes Research Articles

Enhancing hydrogen evolution: Carbon nanotubes as a scaffold for Mo2C deposition via magnetron sputtering and chemical vapor deposition

This study presents an innovative approach to fabricating carbon nanotubes (CNTs) through magnetron sputtering and chemical vapor deposition (CVD). These CNTs serve as a robust structural scaffold for the deposition of molybdenum, which, through thermal annealing, becomes molybdenum carbide (Mo2C), which is highly efficient for hydrogen evolution reaction (HER). Our investigation delves into the physical and chemical attributes of these electrodes, revealing insights into the functionality of Mo2C on CNTs hybrid structures. Chemical characterization confirms the exceptional performance of the electrode. Our Mo2C on CNT hybrid system showcases remarkable electrocatalytic activity, with an onset potential of 103 mV at 1 mA/cm2 and an overpotential of 176 mV at 10 mA/cm2. Further validation comes from tests revealing a Tafel slope of 95 mV/dec, affirming its superiority in facilitating HER. Unparalleled combination of low charge transfer resistance and accelerated reaction kinetics, Mo2C on CNTs hybrid structure is poised to significantly enhance HER activity.

Fabrication of a novel magnetic carbon nanotube coated with polydopamine modified with EDTA for removing Cd2+ and Pb2+ ions from an aqueous solution

This work demonstrates the preparation of a new, effective, and reusable magnetic adsorbent by functionalizing dopamine with ethylenediaminetetraacetic dianhydride and polymerizing it on the surface of magnetic carbon nanotubes (EDTA@PD-CNT/Fe3O4). The adsorbent was analyzed using XRD, FT-IR, Zeta potential, FE-SEM, EDX, BET, TGA, DTA, and VSM. The synthesized adsorbent was used to remove lead and cadmium ions from aqueous solution. The adsorption process was improved by optimizing key parameters such as pH, adsorbent dosage, contact time, and ion concentration. For both ions, the thermodynamic data of the processes and adsorption kinetics were examined. Analyzing the experimental data revealed that the Langmuir isotherm was the most appropriate model, and the examination of adsorption kinetics showed a pseudo-second-order equation. The adsorption process by the EDTA@PD-CNT/Fe3O4 adsorbent was spontaneous and endothermic, according to the thermodynamic data, for Cd2+ and Pb2+, the highest adsorption capacities were found to be 204.54 mg g−1 and 376.48 mg g−1, respectively.

In-situ self-catalyzed fabricating carbon nanotubes on [010] preferential LiMn0.5Fe0.5PO4 nanoplates to achieve excellent high rate performance

Nano carbon material composites significantly enhance the performance of lithium manganese iron phosphate (LMFP) cathode materials. This study investigates the self-catalytic growth mechanism of highly conductive carbon nanotubes (CNTs) on bare LMFP particles via chemical vapor deposition (CVD), focusing on the influence of particle size and crystallographic orientation. It is found that the Fe3C particles formed on static solvothermal synthesized LMFP nanoplates with high [010] orientation were effective to catalyze the generation of CNTs. Diverse CVD durations produced CNTs coatings with varying structures to impact electrochemical properties of final products. The MP-L/CNTs-2 sample, with 3.6 wt% carbon, showed the highest reversible capacity of 158 mAh g−1 at 1 C with 99.3 % capacity retention after 400 cycles, after 3000 cycles at 10 C, the retention rate was 74.5 %. In contrast, LMFP synthesized via solid-phase method (MP-S/C) only formed a carbon film on the surface and delivered 143 mAh g−1 at 1 C (97.6 % retention after 400 cycles) with prominent capacity loss at 10 C. This study provides new insights into the self-catalytic growth mechanism of CNTs to promote ion-electron conductivity and structural stability of LMFP materials, thus improving kinetic property and cycling stability for high-performance lithium-ion batteries.

The Low-Temperature Growth of Carbon Nanotubes Using Nickel Catalyst

This study presents the results of a comprehensive investigation into the fabrication of single-walled carbon nanotubes (SWCNTs) employing chemical vapor deposition (CVD) technique, with nickel nanoparticles serving as crucial catalysts. These nanoparticles are synthesized via the reduction of oxide precursors using hydrogen and are strategically incorporated with ethanol vapor as the primary carbon source. The effectiveness and reproducibility of this synthesis method are thoroughly validated using advanced analytical techniques. Particularly noteworthy is the demonstrated ability to conduct the process at relatively low temperatures, not exceeding 500°C, which is of significant importance. Such precise control over synthesis conditions not only augurs well for the scalability of SWCNT production but also carries substantial implications for the advancement of nanomaterial synthesis methodologies.

Recent Advances in Carbon Nanotube Technology: Bridging the Gap from Fundamental Science to Wide Applications

Carbon nanotubes, as carbon allotropes distinguished by their intricate structures and exceptional physicochemical properties, have demonstrated substantial progress in recent years across diverse domains, including energy production, chemical synthesis, and environmental preservation. They exhibit notable attributes such as high thermal stability, superior adsorption capacity, and a substantial specific surface area, rendering them superb catalyst supports. Particularly in electrochemical energy storage, CNTs are extensively employed in supercapacitor electrodes owing to their elevated electrical conductivity, mechanical robustness, and electrocatalytic prowess, which facilitate significant energy storage capabilities. Their intricate pore architecture and reactive sites make functionalized carbon nanotubes well suited for synthesizing composite materials with diverse components, which are ideal for sequestering carbon dioxide from both atmospheric and indoor environments. This review presents a comprehensive examination of carbon nanotube synthesis methodologies, encompassing chemical vapor deposition, arc discharge, and laser ablation, and evaluates their impacts on the structural and functional properties of carbon nanotubes. Furthermore, this article underscores the applications of carbon nanotubes in fields such as fuel cells, photocatalysis, ammonia synthesis, dry methane reforming, Fischer–Tropsch synthesis, and supercapacitors. Despite the considerable potential of carbon nanotubes, their manufacturing processes remain intricate and costly, impeding large-scale industrial production. This review concludes by addressing the challenges in fabricating carbon nanotube composites and outlining future development prospects.

Sodium alginate/guar gum/multi-walled carbon nanotubes-based hydrophobic Joule thermal textiles for enhanced body thermal management and dehumidification

A sodium alginate (SA), guar gum, and multi-walled carbon nanotube composite solution was prepared using a simple blending method, followed by the construction of alginate/guar gum/multi-walled carbon nanotube fibers and fabrics through complexation with various metal ions (zinc, copper, calcium), featuring multiple hydrogen bonds and ionic complex structures. Specifically, the sodium alginate zinc/guar gum/multi-walled carbon nanotube (SA/GG/Zn2+/MWCNTs) composite fibers exhibited a significant Joule heat effect. By integrating with electronic components such as a temperature control switch, a wearable device capable of operating in cold and humid environments for dehumidification and warming was fabricated. The SA/GG/Zn2+/MWCNTs composite fabric demonstrated excellent hydrophobicity, with a contact angle reaching 145.4°, significantly enhancing its resistance to droplet penetration. Under a 5V voltage, the composite fabric rapidly generated Joule heat, increasing the surface temperature by 5∼7 °C (sensible heat) within just 40 s. Additionally, part of its energy (latent heat) transformed the tiny droplets adhering to the fabric's surface from liquid to gas, achieving dehumidification. This research provides an important theoretical and practical foundation for enhancing the performance and energy efficiency of personal thermal management textiles.

Selective laser melting fabricated carbon nanotube reinforced 18Ni300 maraging steel directly used for mold repairing

The extreme working conditions of 18Ni300 Maraging steel (MS) lead to the damage of molds, thus there is a constant demand of mold repairing. However, neither medium carbon steels nor 18Ni300 MS itself can ensure better compatibility with the aged-18Ni300 MS substrate. Therefore, 0.2 wt% CNTs were added to form 18Ni300/CNT composite through selective laser melting (SLM). This addition refines the grain size and leads to the formation of (Ti, Mo)C carbides. Due to the grain refinement strengthening and precipitation strengthening, both tensile strength and elongation of 18Ni300/CNT composite improved in comparison to the as-built 18Ni300 MS. The impact toughness also increases from 46 ± 1.5 J/cm2 to 62 ± 2 J/cm2. The comparable mechanical properties between 18Ni300/CNT composite and aged-18Ni300 MS suggests that this composite can be directly used for mold repairing without post heat treatment, presenting a promising and cost-effective method to prolong the mold lifetime.

Joule Heating in Controlled Atmospheres to Process Nanocarbon/Transition Metal Oxide Composites and Electrodes.

Composites of nanocarbons and transition metal oxides combine excellent mechanical properties and high electrical conductivity with high capacitive active sites. These composites are promising for applications such as electrochemical energy conversion and storage, catalysis, and sensing. Here, we show that Joule heating can be used as a rapid out-of-oven thermal processing technique to crystallize the inorganic metal oxide matrix within a carbon nanotube fabric (CNTf) composite. We choose manganese oxide and vanadium oxide as model metal oxides and show that the Joule heating process is rapid and enables accurate control over the temperature and phase transitions. Next, we use thermogravimetric analysis and Joule heating experiments in controlled atmospheres to show that metal oxides can actually catalyze thermal degradation and reduce the thermal stability of the CNTs, which could limit processing of many oxides. We solve this by using a reducing hydrogen atmosphere to successfully extend the Joule processing window and thermal stability of the CNTf/metal oxide composite to ∼1000 °C.

Carbon nanotube fibers with dynamic strength up to 14 GPa.

High dynamic strength is of fundamental importance for fibrous materials that are used in high-strain rate environments. Carbon nanotube fibers are one of the most promising candidates. Using a strategy to optimize hierarchical structures, we fabricated carbon nanotube fibers with a dynamic strength of 14 gigapascals (GPa) and excellent energy absorption. The dynamic performance of the fibers is attributed to the simultaneous breakage of individual nanotubes and delocalization of impact energy that occurs during the high-strain rate loading process; these behaviors are due to improvements in interfacial interactions, nanotube alignment, and densification therein. This work presents an effective strategy to utilize the strength of individual carbon nanotubes at the macroscale and provides fresh mechanism insights.

Preparation of graphene oxide and multi-walled carbon nanotubes, and they are used to modify the glassy carbon electrode for sensing Enalapril Maleate

In this study, the graphene oxide and multi-walled carbon nanotubes fabrication was evaluated using (SEM), (FTIR), Raman spectroscopy and (XRD). The results showed promising accuracy for the graphene oxide and multi-walled carbon nanotubes voltammetric sensor. The direct voltammetric determination of Enalapril Maleate in pharmaceutical samples, urine, and serum is detailed using a straightforward and extremely sensitive technique. Graphene oxide-multiwall carbon nanotubes are added to glassy carbon electrodes in an efficient manner to activate the GO-MWNT structures, which then electrocatalyzes the reduction of Enalapril Maleate. The results of the cyclic voltammetric (CV) experiment showed that the electrocatalytic activity of GO-MWNTs to reduce Enalapril Maleate was significantly improved, leading to a much higher cathodic peak current for EM. This finding opens the door to the possibility of creating a very sensitive voltammetric sensor to detect EM in biological and pharmaceutical fluid samples. A linear calibration curve in the 2.5–12.5 ppm concentration range, a detection limit of 0.2 ppm, and a relative standard deviation (R.S.D.%) lower than 1.0 % (n = 5) were all indicative of ideal conditions. Lastly, EM is a diffusion-controlled process that proceeds through a two-electron-two-proton change, which provides a mechanism for the reduction of EM.. The GO-MWCNTs/GCE sensor had a good repeatability and excellent reproducibility, R.S.D.% =1.77 and 1.82.

Fabrication of superior conductive composite yarn with 3D continuous CNT/WPU structure for high-performance stretchable heater and sensor

Composite yarns based on coating are suitable for broad application fields and massive production due to the flexibility, efficient fabrication, and economic feasibility. However, challenges remain for composite yarns to simultaneously meet the stringent requirements for stretchability, durability, and functionality in practical application. Herein, we report the fabrication of carbon nanotube (CNT)/waterborne polyurethane (WPU) composite yarn (C/WCY) by inducing CNT/WPU composite ink to construct a 3D continuous conductive structure in draw texturing yarn (DTY) through the capillary effect. Consequently, a high loading of 49 wt% CNTs and conductivity of over 2.3 × 103 S/m were achieved, which enabled C/WCY fast thermal response (120 °C within 8 s), long-term durability, superb electrothermal conversion efficiency (hr+c = 1.38 mW/°C), and excellent electrical properties. The stretchable heater and wearable sensors based on C/WCY were further achieved by braiding and weaving technology. This work offered new opportunities for scalable, fast, and low-cost fabrication of wearable electric devices.

Facile and efficient fabrication of carbon nanotube reinforced epoxy vitrimers through dynamic crosslinking

AbstractCarbon nanotubes (CNT) is an ideal candidate for reinforced epoxy vitrimer composites, however, achieving a desirable improvement of the mechanical properties is a great challenge owing to CNT is extremely easy to aggregate. In this study, well‐dispersed CNT reinforced epoxy vitrimers, namely EVD/CNT, were prepared by combining ultrasonic dispersion and dynamic crosslinking techniques, using multiple wall carbon nanotube as reinforcement filler, sebacic acid as curing agent, diglycidyl ether of bisphenol A (DGEBA) as epoxy monomer, zinc acetylacetonate as transesterification catalyst, torque rheometer (internal mixer) as dynamic crosslinking equipment. The CNT reinforced epoxy vitrimers, namely EVS/CNT, were prepared using traditional static curing method. The structure and morphology, mechanical properties and stress relaxation behavior of EVS/CNT and EVD/CNT were comparatively investigated, and the influence of CNT content on the structure and properties of EVD/CNT prepared by dynamic crosslinking method were also studied. The results indicated that dynamic crosslinking technology can stably disperse CNT into epoxy vitrimer resin matrix under continuous shear force. However, CNT experienced severe secondary agglomeration during the static curing process. When the loading amount of CNT was 2 wt%, the tensile strength and elongation at break of EVD/CNT‐2 were 3.2 times and 2.2 times higher than those of EVS/CNT‐2, respectively. The Young's modulus and glass transition temperature (Tg) of EVD/CNT‐2 (6.43 ± 1.10 MPa, 29.6°C) were also higher than those of EVS/CNT‐2 (5.46 ± 0.31 MPa, 25.4°C). Moreover, dynamic crosslinking technology greatly shortened the reaction time of CNT reinforced epoxy vitrimers, improved production efficiency and reduced reaction energy consumption, and was expected to be used for large‐scale and industrial production.

Facile fabrication of binder-free carbon nanotube–carbon nanocoil hybrid films for anodes of lithium-ion batteries

Facile fabrication of binder-free carbon nanotube–carbon nanocoil hybrid films for anodes of lithium-ion batteries

Mechanistic study of highly effective phosphate removal from aqueous solutions over a new lanthanum carbonate fabricated carbon nanotube film

The effective purification of phosphate-containing wastewater is considered as increasingly important. In this study, a highly effective LC-CNT film was developed for efficient phosphate removal. Kinetic results showed that the adsorbent exhibited an improved mass transfer efficiency and a fast adsorption rate during adsorption (reaching 80% and 100% equilibrium adsorption capacity within 175 and 270 min, respectively). Kinetic model analysis suggested that the adsorption was a combined chemical physical process. Isotherm study revealed that the LC-CNT film showed a superior adsorption capacity (178.6 mg/g, estimated from the Langmuir model) with multiple adsorption mechanisms. pH study suggested that surface complexation and ligand exchange played important roles during adsorption, and the adsorbent worked well within the pH range of 3–7 with little La leakage. The ionic strength and competing anions showed little influence on the adsorbent effectiveness except for the carbonate and sulfate ions. The characterization and mechanism study revealed that the phosphate adsorption of the LC-CNT film was controlled by inner-sphere complexation, outer-sphere complexation and surface precipitation. The LC-CNT film also showed excellent regenerability and stability in cycling runs, further demonstrating its potential in industrial applications.

Controllable fabrication of N-doped carbon nanotubes coated Co4N nanoparticles to boost hydrogen evolution reaction

Transition metal nitrides (TMNs) have attracted great attention as ideal active materials in the field of electrocatalysts in recent years due to their excellent electrical conductivity, wide band gap and adjustable morphology. Pure phase Co4N nanoparticles encapsulated nitrogen-doped carbon (NC) nanotubes (Co4N@NC) were in-situ synthesized by one-pot method. In this paper, the morphology of carbon nanotubes is controlled by adjusting the pyrolysis time, so that more active sites are exposed on carbon nanotubes. Thus, the cobalt nitride catalyst with excellent catalytic performance for hydrogen evolution reaction (HER) in acidic electrolyte was obtained. In summary, due to the protection of mesoporous nitrogen-doped carbon to Co4N nanoparticles, large electrochemically active surface area, good conductivity and more exposed active sites, Co4N@NC possesses excellent HER performance in acidic electrolytes. The overpotential of Co4N@NC at the current density of 10 mA cm−2 is 117 mV (η10), and it shows long-term stability in 0.5 M H2SO4 solution for 50 h. This study provides a strategy for the development of catalysts for the controllable synthesis of high-performance transition metal nitrides.

Opinions on the Development of Ultrahigh Permeation Membranes

In this work, recent progresses made in the development of membranes with ultrahigh permeation rate for reverse osmosis (RO) and membrane distillation (MD) are briefly summarized and the future prospect of those membranes is discussed. In fabrication of ultrahigh permeation RO membranes, carbon nanotube, aquaporin, graphene and fluorous oligoamide nanorings were used and in all of them several orders of magnitude higher fluxes than the conventional commercial membranes were achieved. Ultrahigh MD membranes were fabricated mostly from carbonaceous materials also with several orders of magnitude higher fluxes than conventional commercial membranes, except for those made of ultrathin polymeric material, which demonstrated a high flux at a low transmembrane temperature difference. Despite these remarkable achievements, it was concluded that many challenges would be encountered to produce a sufficient amount of water by the so-called membrane chips.

In-Situ Flame-Synthesized Carbon Nanomaterials via an Impinging Swirl Flow with an N-Butanol Pool

ABSTRACT This study aims to investigate the impact of flow rotation and oxygen concentration on the synthesis of carbon nanomaterials using n-butanol diffusion flames in a rotating stagnation flow with a liquid pool and a catalytic Ni substrate. With increasing angular velocity (ω), the diffusion flame shifts slightly toward the upper oxidizer nozzle, experiences a lower strain rate, and becomes stronger with a higher maximum flame temperature at a fixed oxygen concentration (ΩO). Meanwhile, the soot layer thickens and gradually turns yellowish. Field Emission Scanning Electron Microscopy (FESEM) analyses confirm that carbon nanotubes (CNTs) can only be fabricated at ω = 2 or 3 rps when ΩO = 21%, highlighting the critical role of flow rotation. Interestingly, the optimal positions for CNT synthesis consistently occur at the same sampling position (1.5 mm below the upper edge of the blue flame) for all values of oxygen concentration (ΩO). The corresponding temperature ranges for ΩO = 19%, 18%, and 17% are approximately 950°C, 820–920°C, and 800–850°C, respectively, which align with existing literature. High-resolution transmission electron microscopy (HRTEM) images reveal both typical straight tubular and bamboo-like CNT structures. Raman spectra indicate superior graphitization at high angular velocities (ω). Notably, at ω = 0 rps, the intensity ratio of the D- and G-bands is greater than 1 (ID/IG >1); however, as ω increases, the opposite holds (ID/IG <1), with its value gradually decreasing. This suggests that the swirl effect enhances graphite layer crystallization. Importantly, the strain rate controlled by flow rotation significantly influences CNT fabrication, considering both residence time and carbon source. The key finding of this study is that swirl flow enhances both the quality and quantity of CNTs synthesized via n-butanol diffusion flames.

Underwater Thermoacoustic Generation by a Hierarchical Tetrapodal Carbon Nanotube Network.

Solid-state fabricated carbon nanotube (CNT) sheets have shown promise as thermoacoustic (TA) sound generators, emitting tunable sound waves across a broad frequency spectrum (1-105 Hz) due to their ultralow specific heat capacity. However, their applications as underwater TA sound generators are limited by the reduced mechanical strength of CNT sheets in aqueous environments. In this study, we present a mechanically robust underwater TA device constructed from a three-dimensional (3D) tetrapodal assembly of carbon nanotubes (t-CNTs). These structures feature a high porosity (>99.9%) and a double-hollowed network of well-interconnected CNTs. We systematically explore the impact of different dimensions of t-CNTs and various annealing procedures on sound generation performance. Furnace-annealed t-CNTs, in contrast to directly resistive Joule heating annealing, provide superior, continuous, and homogeneous hydrophobicity across the surface of bulk t-CNTs. As a result, the t-CNTs-based underwater TA device demonstrates stable, smooth, and broad-spectrum sound generation within the frequency range of 1 × 102 to 1 × 104 Hz, along with a weak resonance response. Furthermore, these devices exhibit enhanced and more stable sound generation performance at nonresonance frequencies compared to regular CNT-based devices. This study contributes to advancing the development of underwater TA devices with characteristics such as being nonresonant, high-performing, flexible, elastically compressible, and reliable, enabling operation across a broad frequency range.

Improving Carbon Nanotube-Based Radiofrequency Field-Effect Transistors by the Device Architecture and Doping Process.

The semiconducting carbon nanotube (CNT) has been considered a promising candidate for future radiofrequency (RF) electronics due to its excellent electrical properties of high mobility and small capacitance. After decades of development, great progress has been achieved on CNT-based RF field-effect transistors (FETs). However, almost all elevations are owing to advancement of the CNT materials and fabrication process, while the study of device architecture is seldom considered and reported. In this work, we innovatively combined device architecture and related doping processes to further optimize CNT-based RF FETs by guiding process or materials with collaborative optimization for the first time and explore their effect on device performance carefully and statistically. Based on more mature random-oriented CNT materials, we fabricated CNT-based RF FETs having three different gate positions of device architecture variation accompanied by suitable doping schemes. The optimized FETs obtained 2-3 times of current density (transconductance) and 1.3 times the cutoff frequency and maximum oscillation frequency compared with unoptimized devices at the same channel length. After transistor-level verification of effect, we further built a CNT RF amplifier and demonstrated almost 10 dB of transducer gain improvement operating at 8 GHz for X-band application. The achieved results from this work would help further improve CNT RF performance beyond the materials and process point of view.

Pristine and Coated Carbon Nanotube Sheets—Characterization and Potential Applications

A carbon nanotube (CNT) sheet is a nonwoven fabric that is being evaluated for use in different textile applications. Several properties of pristine CNT sheets and CNT sheets coated with a polysilazane sealant and coating were measured and compared in the paper. The polysilazane coating is used to reduce the shedding of CNT fibers from the sheet when the sheet is in contact with surfaces. Most fabrics show some shedding of fibers during the washing or abrasion of the fabric. This study showed that the coating reduces the shedding of fibers from CNT fabric. The coating also increased the flame resistance of the fabric. The pristine and coated sheets both have low strength but high strain to failure. The pristine and coated CNT sheet densities are 0.48 g/cc and 0.65 g/cc, respectively. The pristine CNT sheet is approximately 27 μ thick. The coated sheet is approximately 24 μ thick. The coating may have densified the sheet, making it thinner. The thickness of the compliant sheets was difficult to measure and is a source of error in the properties. Characterization results are given in this paper. The results are for comparison purposes and not to establish material properties data. Possible applications for CNT sheets are briefly discussed.