Fabrication Of Carbon Nanotubes Research Articles

Fabrication and Characterization of Carbon Nanotube Filled PDMS Hybrid Membranes for Enhanced Ethanol Recovery.

Ethanol separation via the pervaporation process has shown growing application potential in solvent recovery and the bioethanol industry. In the continuous pervaporation process, polymeric membranes such as hydrophobic polydimethylsiloxane (PDMS) have been developed to enrich/separate ethanol from dilute aqueous solutions. However, its practical application remains largely limited due to the relatively low separation efficiency, especially in selectivity. In view of this, hydrophobic carbon nanotube (CNT) filled PDMS mixed matrix membranes (MMMs) aimed at high-efficiency ethanol recovery were fabricated in this work. The filler K-MWCNTs was prepared by functionalizing MWCNT-NH2 with epoxy-containing silane coupling agent (KH560) to improve the affinity between fillers and PDMS matrix. With K-MWCNT loading increased from 1 wt % to 10 wt %, membranes showed higher surface roughness and water contact angle was improved from 115° to 130°. The swelling degree of K-MWCNT/PDMS MMMs (2 wt %) in water were also reduced from 10 wt % to 2.5 wt %. Pervaporation performance for K-MWCNT/PDMS MMMs under varied feed concentrations and temperatures were evaluated. The results supported that the K-MWCNT/PDMS MMMs at 2 wt % K-MWCNT loading showed the optimum separation performance (compared with pure PDMS membranes), with the separation factor improved from 9.1 to 10.4, and the permeate flux increased by 50% (40-60 °C, at 6 wt % feed ethanol concentration). This work provides a promising method for preparing a PDMS composite with both high permeate flux and selectivity, which showed great potential for bioethanol production and alcohol separation in industry.

Fabrication of carbon nanotubes with rich Pyridinic nitrogen in H2/Ar atmosphere for efficient electroreduction of CO2 to CO

Fabrication of carbon nanotubes with rich Pyridinic nitrogen in H2/Ar atmosphere for efficient electroreduction of CO2 to CO

Processing of Composite Electrodes of Carbon Nanotube Fabrics and Inorganic Matrices via Rapid Joule Heating.

Composites of nanocarbon network structures are interesting materials, combining mechanical properties and electrical conductivity superior to those of granular systems. Hence, they are envisaged to have applications as electrodes for energy storage and transfer. Here, we show a new processing route using Joule heating for a nanostructured network composite of carbon nanotube (CNT) fabrics and an inorganic phase (namely, MoS2), and then study the resulting structure and properties. To this end, first, a unidirectional fabric of conductive CNT bundles is electrochemically coated with MoS2. Afterward, the conformally coated inorganic phase is crystallized via heat generated by direct current passing through the CNT ensemble. The Joule heating process is rapid (maximum heating rate up to 31.7 °C/s), enables accurate temperature control, and takes only a few minutes. The resulting composite material combines a high electrical conductivity of up to 1.72 (±0.25) × 105 S/m, tensile modulus as high as 8.82 ± 5.5 GPa/SG, and an axial tensile strength up to 200 ± 58 MPa/SG. Both electrical and mechanical properties are orders of magnitude above those of wet-processed nanocomposites of similar composition. The extraordinary longitudinal properties stem from the network of interconnected and highly aligned CNT bundles. Conductivity and modulus follow approximately a rule of mixtures, similar to a continuous fiber composite, whereas strength scales almost quadratically with the mass fraction of the inorganic phase due to the inorganic constraining realignment of CNTs upon stretching. This processing route is applicable to a wide range of nanocarbon-based composites with inorganic phases, leading to composites with specific strength above steel and electrical conductivity beyond the threshold for electronic limitations in battery electrodes.

Incorporating Cerium Vanadate into Multi-Walled Carbon Nanotubes for Fabrication of Sensitive Electrochemical Sensors toward Sulfamethazine Determination in Water Samples

We developed a simple hydrothermal technique for the fabrication of a flexible integrated composite containing cerium vanadate (CeVO4) and multi-walled carbon nanotubes (MWCNTs). The CeVO4/MWCNTs composite possessed good conductivity and interesting electrochemical catalytic performance when immobilized on a glassy carbon electrode (GCE). This CeVO4/MWCNTs-GCE sensor provided excellent analytical performance for the detection of the sulfonamide antibacterial drug sulfamethazine (SMZ). Benefiting from the significantly enlarged surface area of the modified electrode and the catalytic effect of CeVO4-MWCNTs, the sensor offered high sensitivity, good stability, fine selectivity, and a remarkable limit of detection (LOD) of 0.02 μM. Furthermore, the sensor also exhibited ideal performance with good recovery and precision when applied to SMZ residue detection in real aquaculture water samples.

Influence of electrode processing and electrolyte composition on multiwall carbon nanotube negative electrodes for sodium ion batteries

Nanostructured one-dimensional multiwall-carbon nanotubes have a variety of advantageous properties including good electrical conductivity and mechanical strength, and thus have been widely investigated for use in lithium-ion battery electrodes as conductive and microstructural additives, though they also possess some electrochemical activity. Their application to sodium-ion batteries has been less extensively researched, and therefore a greater understanding of the electrochemical reaction with sodium, and effects of slurry composition and electrolyte formulation is warranted, especially as these are likely components in future Na-ion electrode formulations. Here, we report the fabrication of aqueous and organic multi-wall carbon nanotube (MWCNT) negative electrodes processed by ball milling. The binder of choice is noted to greatly affect the electrochemical performance, both in terms of capacity retention and rate capability over a range of current densities from 25 to 500 mA g−1. Switching from a carbonate- to diglyme-based electrolyte considerably improves initial coulombic efficiencies (∼10%–60%), attributed to less extensive formation of solid electrolyte interphase, and enables a reversible mechanism with capacities up to 150 mAh g−1 over 100 cycles depending upon the binder used. Ex-situ characterization of the discharged and cycled carbon nanotubes by powder x-ray diffraction, transmission electron microscopy and Raman spectroscopy provide an insight into how MWCNTs undergo sodiation and demonstrate a partially reversible structural transformation during cycling when using the diglyme-based electrolyte. This work lays the foundation for a better understanding of these versatile materials, especially when used in the most promising alternative energy storage technology to lithium ion.

Fabrication of CNTFET Simulation Using Cadence Virtuoso

In this paper, the fabrication of CNTFET with the help of simulation using cadence virtuoso is presented. The process of fabricating Carbon Nanotube Field-Effect Transistors (CNTFETs) is a sophisticated task that demands great attention to detail. To aid in the design and optimization of CNTFET fabrication processes, simulation tools are often utilized. CNTFET fabrication simulations generally involve modeling the physical and chemical processes of creating the carbon nanotube channel, as well as the device's metal contacts and other components. Simulation tools such as COMSOL Multiphysics or Lumerical are used to model the mechanical, thermal, and electrical properties of the materials involved, and to predict how they will behave during fabrication. An essential challenge in CNTFET fabrication is obtaining precise control over the nanotube placement and orientation, which can be addressed through modeling the nanotube growth and optimizing the growth parameters to achieve the desired properties. Furthermore, simulations can assist in optimizing the process parameters for depositing metal contacts on the nanotubes, which is critical for achieving good device performance. Overall, simulation tools play a vital role in the CNTFET fabrication process, enabling researchers to optimize the device design and fabrication parameters for improved performance and yield. The work done & presented in this paper is the result of the mini-project work that has been done by the first sem engineering students of the college and as such there is little novelty in it and the references are being taken from various sources from the internet, the paper is being written by the students to test their writing skills in the starting of their engineering career and also to test the presentation skills during their mini-project presentation. The work done & presented in this paper is the report of the assignment / alternate assessment tool as a part and parcel of the academic assignment of the first year subject on nanotechnology & IoT.

Efficient Fabrication of Carbon Nanotube-Based Stretchable Electrodes for Flexible Electronic Devices.

Stretchable electrodes are highly demanded in various wearable and flexible electronic devices, whereas the efficient fabrication approach is still a challenge. In this work, an efficient shrinking method to fabricate carbon nanotube (CNT)-based stretchable electrodes is proposed. The electrode is a layer of anisotropic CNT wrinkling film coated on a latex balloon substrate (CNT@latex), whose resistivity remains stable after 25000 stretching cycles of 0 to 50% tensile strain, and can survive up to 500% tensile train. The highly conductive electrode can be used as the current collector of a stretchable Zinc-ion battery, maintaining an output voltage of 1.3V during the stretching process of 0 to 100%. The applications of the electrode in flexible triboelectric nanogenerators and Joule heating devices are also demonstrated, further indicating their good prospects in the field of stretchable electronic devices.

Polypyrrole Modified Carbon Nanotube/Polyimide Electrode Materials for Supercapacitors and Lithium-ion Batteries

Lithium-ion batteries have evolved and transcended in recent years to power every device across the spectrum, from watches to electrical vehicles and beyond. However, the lithium-ion battery requires the use of heavy and expensive transition metal oxides that have limited life cycles. Conductive polymer nanocomposites have been shown to possess good electrochemical and thermomechanical properties and are considered to be effective alternatives to transition metal oxides. The fabrication and properties of polyimide matrix-single wall carbon nanotube, SWCNT composite electrode materials, modified by the electrodeposition of polypyrrole, PPy was successfully carried out. The doping of PPy with p-Toluene sulfonic acid, T resulted in a dramatic transformation of the morphology and specific capacitance of the electrode material. Electrochemical impedance spectroscopy, EIS, cyclic voltammetry, CV, and galvanic charge–discharge tests were used to measure the electrode’s specific capacitance and specific capacity. Maximum specific capacitance values of up to 84.88 F/g and 127.13 F/g were obtained by CV and charge–discharge tests, respectively. A capacitance retention of over 80% was obtained after over 500 cycles of testing. The insertion of doped PPy into the electrode material by electrochemical polymerization was shown to positively correlate to the improved electrochemical performance of the nanocomposite. An increase in the porosity of about 34.68% over the non-doped polypyrrole was obtained from EIS measurement and supported by the optical microscope pictures. Increasing the process parameters, such as pyrrole, Py concentration and the amount of dopants, lead to a dramatic increase in the specific capacitance and capacity of the composite electrodes.

Efficient Fabrication of High-Quality Single-Walled Carbon Nanotubes and Their Macroscopic Conductive Fibers.

High-purity and well-graphitized single-walled carbon nanotubes (SWCNTs) with excellent physiochemical properties are ideal building blocks for the assembly of various CNT macrostructures for a wide range of applications. We report the preparation of high-quality SWCNTs on a large scale using a floating catalyst chemical vapor deposition (FCCVD) method. Under the optimum conditions, the conversion rate of the carbon source to SWCNTs reached 28.8%, and 20.4% of the metal nanoparticles were active for SWCNT growth, which are 15% and ∼400 times higher than those previously reported for FCCVD synthesis, respectively. As a result, the prepared SWCNTs have a very low residual catalyst content of ∼1.9 wt % and a high rapid oxidation temperature of 717 °C. Using these high-quality SWCNTs, we spun macroscopic SWCNT fibers by a wet-spinning process. The resulting fibers had a high electrical conductivity of 6.67 MS/m, which is 32% higher than the best value previously reported for SWCNT fibers.

Rational designing carbon nanotubes incorporated oxygen vacancy-enriched bimetallic (Ni, Co) oxide nanocages for high-performance hybrid supercapacitor

NiCo bimetallic oxide with low cost and high theoretical capacity is the candidate for high-performance supercapacitor electrodes, but the low conductivity and short cycle life of oxides have hindered their development. Herein, we designed a novel strategy for the fabrication of carbon nanotubes (CNT) incorporated oxygen vacancy (OV) NixCo1-xO nanocages for high performance supercapacitor. The existing oxygen vacancy in OV-NixCo1-xO nanocage changes the electronic environment on the crystal surface and provides more active sites, leading to the enhanced electrical conductivity together with CNT and capture capability for OH–. This CNT/OV-NixCo1-xO composite achieves high capacitance of 1400.7 F g−1 at the current density of 1 A g−1. When assembled a hybrid supercapacitor device of CNT/OV-NixCo1-xO//activated carbon, it exhibits an excellent energy density of 52.7 Wh kg−1 at a power density of 800 W kg−1. Besides, the device exhibited a capacity retention of 85.7 % over up to 10,000 cycles. This work provides a feasible strategy for surface vacancy regulation of Prussian blue derivatives used in high performance supercapacitor.

Two birds with one stone: Simultaneous fabrication of HfC nanowires and CNTs through efficient utilization of polymer-derived ceramics

• Carbon nanotubes (CNTs) were fabricated by using the waste gasses when preparing hafnium carbide nanowires (HfC NWs ) through thermal pyrolysis of Hf-containing precursor. • The CO and CH 4 released by Hf-containing precursor are the main carbon source for the growth of CNTs. • The in situ growth of HfC NWs increased the flexural strength of carbon/carbon (C/C) composites, and CNTs/carbon cloth displayed enhanced electrochemical performance. Carbon nanotubes (CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires (HfC NWs ) through thermal pyrolysis of Hf-containing polymer precursor. The formed HfC NWs are distributed uniformly on the surface of the carbon fibers in carbon/carbon (C/C) composites and display perfect single crystal appearance. The pyrolysis of the Hf-containing organic precursor provides hafnium and carbon source for the growth of HfC NWs . The released waste gasses containing CO, CH 4 and CO 2 are the main carbon source for the growth of CNTs. Specifically, the flexural strength of HfC NWs reinforced carbon/carbon (HfC NWs -C/C) composites is enhanced by ∼105% compared with pure C/C, and the CNTs/carbon cloth also displays improved electrochemical performance with respect to capacitor applications. The present study introduces a novel sustainable and eco-friendly process related to polymer-derived ceramics to form advanced ceramic nanocomposites and proposes a deep understanding of the growth mechanism of CNTs.

Additive Manufacturing of Stretchable Multi-Walled Carbon Nanotubes/Thermoplastic Polyurethanes Conducting Polymers for Strain Sensing.

With the development of science and technology, flexible sensors play an indispensable role in body monitoring. Rapid prototyping of high-performance flexible sensors has become an important method to develop flexible sensors. The purpose of this study was to develop a flexible resin with multi-walled carbon nanotubes (MWCNTs) for the rapid fabrication of flexible sensors using digital light processing additive manufacturing. In this study, MWCNTs were mixed in thermoplastic polyurethane (TPU) photosensitive resin to prepare polymer-matrix composites, and a flexible strain sensor was prepared using self-developed additive equipment. The results showed that the 1.2 wt% MWCNTs/TPU composite flexible sensor had high gauge factor of 9.988 with a linearity up to 45% strain and high mechanical durability (1000 cycles). Furthermore, the sensor could be used for gesture recognition and monitoring and has good performance. This method is expected to provide a new idea for the rapid personalized forming of flexible sensors.

Fabrication of carbon nanotube with high purity and crystallinity by methane decomposition over ceria-supported catalysts

Because of its unique properties, CeO2 is a widely used support material in steam reforming and dry reforming reactions conducted using CH4 as a reactant. However, it has been rarely used in the catalytic decomposition of methane (CDM). In a pre-test, a Co/CeO2 catalyst showed higher activity than Ni/Al2O3, Co/Al2O3, and Mo-Ni/MgO catalysts in the CDM conducted via catalytic chemical vapor deposition (CCVD). Therefore, in this study, the CDM for carbon nanotube (CNT) synthesis over CeO2-supported Co, Fe, and Ni catalysts was investigated, while focusing on the effects of CeO2 on the activities of the active metals in the CDM. Among the investigated catalysts, Ni/CeO2 showed a decent catalytic performance at 600 °C, which is a considerably lower temperature than those previously reported. X-ray diffraction, Brunauer–Emmett–Teller surface area, temperature-programmed reduction/desorption (TPR/TPD), and X-ray photoelectron spectroscopy (XPS) analyses were performed to characterize the catalysts. Through these experiments, it was found that Ni/CeO2 had many adsorption sites for CH4 molecules which could react with mobile oxygen existing in CeO2. Furthermore, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and thermogravimetric (TG) analyses were performed to examine the morphologies and properties of the carbon material grown on the catalysts.

Synergistic Solar-Driven Freshwater Generation and Electricity Output Empowered by Wafer-Scale Nanostructured Silicon.

Electricity generation triggered by the ubiquitous water evaporation process provides an intriguing way to harvest energy from water. Meanwhile, natural water evaporation is also a fundamental way to obtain fresh water for human beings. Here, a wafer-scale nanostructured silicon-based device that takes advantage of its well-aligned configuration that simultaneously realizes solar steam generation (SSG) for freshwater collection and hydrovoltaic effect generation for electricity output is developed. An ingenious porous, black carbon nanotube fabric (CNF) electrode endows the device with sustainable water self-pumping capability, excellent durable conductivity, and intense solar spectrum harvesting. A combined device based on the CNF electrode integrated with nanostructured silicon nanowire arrays (SiNWs) provided an aligned numerous surface-to-volume water evaporation interface that enables a recorded continuous short-circuit current 8.65mA and a water evaporation rate of 1.31kg m-2 h-1 under one sun illumination. Such wafer-scale SiNWs-based SSG and hydrovoltaic integration devices would unchain the bottleneck of the weak and discontinuous electrical output of hydrovoltaic devices, which inspires other sorts of semiconductor-based hydrovoltaic device designs to target superior performance.

Enhanced irradiation-resistance of polymer-derived SiC by incorporation of multiwalled carbon nanotubes

In this work, multiwalled carbon nanotubes were introduced into polycarbosilane to fabricate carbon nanotubes reinforced nano-SiC composites (MWCNTs/ PCS-nano-SiC). Radiation effects on MWCNTs/ PCS-nano-SiC were studied by irradiation with 2 MeV Au2+ ions at room temperature and doses ranging from 2 × 1014 to 8 × 1014 ions/cm2. The sample pyrolyzed at 1400 °C and containing 3 wt% carbon nanotubes exhibited excellent overall performances. The multiple graphite layers in the MWCNTs provided "absorption traps" for defects, improving the efficiency of defect recombination. Tightly combined MWCNTs/ PDC interface is required to enable the two phases to protect each other during irradiation. The critical amorphization dose was increased upon structural optimization, and the hardness degradation was significantly reduced. The rise of Young's modulus at a high damage dose was discovered because of the "interface-driven shrinkage" of nano-SiC. The present study provides insight into SiCf/ SiC design for an advanced nuclear system.

Improving interlaminar properties of woven carbon fibre composite laminates with industrial-scale carbon nanotube fibre interleaves

This work introduces a method to fabricate carbon nanotube fibre veils on woven carbon fibre/epoxy composite laminates and analyses the role of interleaf thickness and degree of infiltration on interlaminar properties. The interlaminar fracture toughness (IFT) under mode I and mode II loading conditions are investigated and discussed comparatively, followed by a systematic analysis of failure and toughening mechanisms. The experimental results revealed that the toughening effects of CNT veils depend highly on their thickness and degree of resin infiltration observed by electron microscopy and Raman spectroscopy. The propagation value of mode I interlaminar fracture toughness (GIC,prop) increased as much as 77 % and 76 % after interleaving CNT veils with a thickness of 5 and 10 μm, but strikingly dropped by 36 % as the thickness of the CNT veils reached up to 15 μm. In comparison, the mode II fracture toughness (GIIC) improved continuously with increasing the thickness of CNT veils. The figure of merit for interlaminar reinforcement, consisting of the change in interlaminar properties normalised by interleaf thickness and ply thickness, comes out as high as 58.5, which is an order of magnitude above the state-of-the-art.

Effects of Carbon Nanotube Diameter on the Fabrication and Performance of Collagen-Inspired Carbon Nanotube Films

High-performance carbon nanotube (CNT) fibers have long been pursued in many academic and industrial communities, and recent decades have witnessed continuous progress in the CNT fiber design and fabrication, although their commercial applications have not been well realized. Inspired by the microstructure of type I collagen fibers, we have proposed a high-throughput route to fabricate CNT fibers/ films by domino-pushing and ion bombarding as-grown CNT forest. With CNTs of small diameter, numerical simulations have demonstrated that the route can well produce collagen-mimicked high-performance CNT fibers with unidirectionally aligned and transversally crosslinked CNTs. As CNT diameter increases, the complex mechanical behaviors such as collapse will probably occur, and hence the influence of the CNT diameter on the fabrication and performance of the fibers needs to be further studied. This work revealed that during the fabrication process the round-to-dumbbell CNT collapse happens with their diameter larger than 2[Formula: see text]nm. Before the collapse, the mechanical performance of the acquired CNT fibers decreases with CNT diameter, but reverses to increase after the collapse, mainly due to the reversed porosity-diameter relation by the collapse behavior. The varying of the fiber mechanical properties with the bombardment energy and dosage was also shown for different CNT diameters. Further, some useful guidelines on the mechanical property and fabrication process design of the bioinspired CNT fibers are concluded.

Fabrication of small-diameter carbon nanotubes using a coordination polymer with a free-oxygen ligand as a catalyst precursor

Carbon nanotubes (CNTs) that are derived from coordination polymers (CPs) and which have controllable structures have served as a significant class of sorbents in renewable materials. However, it is difficult to achieve efficient conversion of CPs to small-diameter CNTs (SDCNTs) via chemical vapor deposition (CVD). As described herein, we first report the large-scale growth of SDCNTs from a Co-based CP. The oxygen atoms of trimesic acid (BTC) which surround the Co-based CP crystals impede the aggregation of Co nanocatalysts so that they effectively serve as a unique “sieve” which allows the catalyst to promote the formation of SDCNTs during the CVD process. CNTs with a diameter of ∼14 nm evolved from the pristine CP architecture. This strategy is novel and provides a new approach for the large-scale preparation of SDCNTs, and it that may facilitate the development of high performance and inexpensive sorbents as well as photocatalysts for water treatment.

Pore structure changes in free-standing single-wall carbon nanotube film on vacuum high-temperature annealing

• Highly pure and crystalline free-standing SWCNT films were fabricated. • Impurities can be removed completely by vacuum high-temperature annealing. • Vacuum annealing can improve crystallinity of SWCNT film. • Vacuum annealing eliminates nanowindows and other defects from SWCNT film. The fabrication of free-standing single-wall carbon nanotube (SWCNT) film is promising for better understanding of SWCNT and many applications. Here we fabricated highly pure and crystalline free-standing SWCNT film using vacuum high-temperature annealing. Impurities can be removed thoroughly by vacuum annealing at 2073 K and 10 −1 Pa for 3 h. Also, the vacuum annealing was quite efficient for removing nanowindows and improving crystallinity of the SWCNT film. The transmission electron microscopic observation and X-ray diffraction confirmed almost no change in the average tube diameter and bundle structure of SWCNT. The vacuum high-temperature annealing decreases the N 2 adsorption amount at 77 K by more than half, supporting closing nanowindows on graphene wall of SWCNT by the vacuum annealing. Our free-standing SWCNT film is expected to promote a fundamental understanding of electrochemical energy issues by the application these films as the well-characterized electrodes.

A Single Step Assembly of Carbon Nanotube Fabric Containing Embedded Copper Particles Produced from Advanced Electrolytic Baths

The electrodeposition of copper particles inside carbon nanotube (CNT) tissues is presented here. Copper electrodeposition inside CNT from aqueous electrolytes has been challenging researchers in recent years, as deposition was mostly restricted to the external surface of the tissue. This work introduces several organic additives, promoting deposition inside the tissue, as well. Electrochemical methods were applied and utilized in order to study the behavior of the CNT in the plating bath, and to analyze the effect of different additives on the deposition of the copper particles. Surface morphology of the coating and the deposits inside the tissue were examined and studies. This work presents an alternative method for the deposition and implementation of copper crystals inside CNT tissue.