High-quality Multi-walled Carbon Nanotubes Research Articles

Mo-Doped Ni/C Catalyst for Improved Simultaneous Production of Hydrogen and Carbon Nanotubes through Ethanol Decomposition.

A Mo-Ni/C catalyst was developed and assessed in terms of the decomposition of ethanol to produce multi-wall carbon nanotubes (MWCNTs) and hydrogen. The catalyst utilized different molar ratios of Mo:Ni (1:9, 2:8, and 3:7), with Mo acting as a dopant to enhance the MWCNT yield and Ni acting as the primary active phase for MWCNT formation. Among the tested ratios, the 2:8 Mo:Ni ratio exhibited the optimal performance, yielding 86% hydrogen and high-quality MWCNTs. In addition to hydrogen, the process also generated CO, CH4, and CO2. Gas chromatography (GC) was employed to analyze the influence of the Mo:Ni ratio on gas production and selectivity, while the quality of the resulting MWCNTs was evaluated using SEM, Raman spectroscopy, and TEM analyses.

High-quality multi-walled carbon nanotubes toughened glass-ceramic by a two-dimension carbon nanotube film interlayer

The brittleness of bioglass/ceramics limits their applications in bone repair. The toughness of the glass matrix can be enhanced by adding nanoscale reinforcements at random; however, the effect is quite limited. This study proposes a novel strategy to prepare controllable fabricating lamellar precursors with multiwalled carbon nanotubes (MWCNTs) film/glass/MWCNTs film sandwich structure by a high-temperature foaming method. Subsequently, the precursor was sintered by spark plasma to obtain a composite material with strong cross-linking between MWCNTs and the glass matrix. The mechanical properties of the composites were characterized, and mechanisms were analyzed by the finite element method. The results revealed that the glass composite with 1.0 wt% MWCNTs had a significantly enhanced fracture toughness (2.65 MPa m1/2) and flexural strength (145 MPa), which were 2.1 times and 1.8 times higher than those of pure glass, respectively. This increase in toughness is attributed to the strong resistance of the well-combined bent and entangled MWCNTs to the fiber pull-out process. The glass/MWCNTs composite showed a low electrical resistivity of 5.8 Ω cm, which would aid skeletal restoration. Thus, this strategy paves a facile way to prepare the highly toughed bio-glass with multifunctional properties.

Smart and sensitive nanomaterial-based electrochemical sensor for the determination of a poly (ADP-ribose) polymerase (PARP) inhibitor anticancer agent

In this research, we propose a novel approach for constructing a sensitive and selective electrochemical sensor utilizing high-quality multi-walled carbon nanotubes functionalized with amino groups (MWCNT-NH2) for the detection of Talazoparib (TLZ), a poly (ADP-ribose) polymerase (PARP) enzyme inhibitor, in real samples. The MWCNT-NH2-based sensor exhibited remarkable performance characteristics, including excellent repeatability, reproducibility, and high selectivity against various interferences. Under optimized conditions, the sensor demonstrated a wide linear concentration range of 1.0–5.0 μM, with a low limit of detection (LOD) of 0.201 μM. Substantiated by rigorous analysis of pharmaceutical and biological matrices, our methodology emerges as a paragon of reliability, boasting recovery rates within the satisfactory bracket of 96.38–105.25%. The successful application of the MWCNT-NH2-based sensor in practical sample analysis highlights its potential for implementation in clinical and pharmaceutical settings. This research not only advances the application of MWCNT-NH2 in electrochemical sensing but also opens new avenues for the development and monitoring of innovative anticancer treatments. The insights gained from our study have far-reaching implications, pointing toward a future where precision and innovation converge to improve patient care and treatment outcomes.

Unravelling the sensory capability of MWCNT-reinforced nanocomposites: Experimental and numerical investigations

Multifunctional nanocomposite strain sensors, especially those that contain dispersed multiwall carbon nanotubes (MWCNTs), are known to possess exceptional electrical conductivity. These nano-reinforced composites can be used for structural health monitoring. It is with this in mind that we focus our attention on calibrating the electromechanical behaviour of MWCNT-reinforced epoxy nanocomposites both numerically and experimentally. In particular, our main objective is to unravel the coupled electromechanical behaviour of the conducting composite prior to failure. In the numerical effort, we adopted the effective-medium homogenization and Mori-Tanaka method to account for tunnelling resistance and to predict the sensory capability of the newly developed composite. In the experimental effort, a conductive epoxy nanocomposite containing high quality MWCNTs randomly dispersed within liquid neat epoxy system was developed. The conducting domains of the developed nanocomposite were characterized using atomic force microscope (AFM) measurements. Electromechanical characterisation of the MWCNT-reinforced nanocomposites was also performed using controlled uniaxial tensile tests to evaluate its sensory capability against load. The results of our work reveal: (i) excellent agreement with the micromechanical model, and (ii) the dramatic influence of the concentration of the MWCNTs, their agglomeration and aggregation on the sensory sensitivity of the MWCNT-reinforced epoxy nanocomposite. Interestingly, an increase in the MWCNT filler loading led to a decrease in the sensory sensitivity of the nanocomposite as measured by uniaxial strain gauge factor. The work was further extended to highlight the sources of errors that could lead to erroneous results in developing and calibrating electrically conducting pathways in polymer nanocomposites.

Directly Using Red Sandstone as a Catalyst to Synthesize Multi-Walled Carbon Nanotubes

Natural catalysts used in the synthesis of carbon nanotubes have significant cost advantages due to their huge reserves, but natural minerals often require complicated pretreatments to obtain satisfactory products. In this study, red sandstone was directly used as a catalyst for the synthesis of multi-carbon nanotubes by chemical vapor deposition without complicated pretreatment. The SEM, TEM, Raman and TG characterization of the products at different growth temperatures ([Formula: see text]C, [Formula: see text]C and [Formula: see text]C) showed that [Formula: see text]C is the optimal condition for the growth of multi-walled carbon nanotubes (MWCNTs) by red sandstone. High-quality multi-wall carbon nanotubes can be obtained with a relatively high yield, and the [Formula: see text] of the product reaches 1.78, which exceeds that of many commercial multi-wall carbon nanotubes. Compared with other natural materials as catalysts for the synthesis of MWCNTs, red sandstone has a huge cost advantage because it can catalyze the synthesis of high-quality MWCNTs at [Formula: see text]C without complicated pretreatment.

Low-cost synthesis of multi-walled carbon nanotubes using red soil as catalyst

Low-cost catalysts are of great significance for the batch synthesis of carbon nanotubes. In this study, the low-cost red soil was directly used as a natural catalyst to catalyze the growth of multi-walled carbon nanotubes (MWCNTs). The results of SEM, TEM, Raman, TG and carbon yields of the products consistently showed that 400 °C calcined red soil lead to high quality MWCNTs growth, the Raman IG/ID of the product is 1.66, which indicates that the product has exceeded the graphitization of many industrially synthesized MWCNTs. The high catalyzation efficiency may be attributed to the fact of composition characteristics that red soil lacks alkali metals and alkaline earth metals but is rich in iron and aluminum oxide, making the composition of red soil similar to the catalyst composition used in the synthesis of carbon nanotubes by common chemical vapor deposition method. Meanwhile the impurity content is less than other natural catalytic materials. The porous structure formed after proper calcination has also played a positive role to the catalytic growth of MWCNTs, which improved catalyst utilization by facilitating the gas phase diffusion. We explored a technique for synthesis of high-quality MWCNTs at low cost using soil as a catalyst.

Effect of pyrolysis temperature on the synthesis of high-quality MWCNTs by CVD method

Production of high-quality Multi-Walled Carbon Nano-Tubes (MWCNTs) is essential in some field, especially in medical and mechanical applications. This work illustrates the synthesis of high-quality (MWCNTs) by Injection Chemical Vapor Deposition (Inj-CVD) method using Ferrocene / Toluene solution as a carbon precursor and a catalyst. The effect of synthesis pyrolysis temperature, which has a pivot impact on the synthesis process, was investigated. The structure defects, impurities, thermal stability and sample morphology, as well as the mean diameters of the MWCNTs, were analyzed using Raman spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscope (SEM), respectively. The results revealed that a change in quality, mean diameter and purity were observed when the pyrolysis temperature varied between 700°C to 850°C. High-quality MWCNTs were observed by Raman spectroscopy at a pyrolysis temperature of 700°C with ID/IG = 0.2. While the outer and inner diameters were 25±6 nm and 7.8±1.5nm respectively, measured by Transmission Electron Microscope (TEM). The Inj-CVD shows an excellent control of the quality of the prepared MWCNTs by optimizing the synthesis temperature.

Impact of Co/Mo ratio on the activity of CoMo/MgO catalyst for production of high-quality multi-walled carbon nanotubes from polyethylene waste

A simple two-stage method was used to produce multiwalled carbon nanotubes (MWCNTs) from low-density polyethylene (LDPE) plastic waste using a group of CoMo/MgO catalysts with several Co/Mo molar ratios (14.5, 6.5, 2.5, 1 and 0.4). The catalytic degradation of LDPE waste was performed using the HZSM-5 catalyst at a low temperature of 400 °C to form non-condensable gases, which were subsequently used as a carbon source for the production of MWCNTs at 700 °C. The influence of Co/Mo ratio on the yield, morphological structure, thermal stability, purity, and quality of MWCNTs was studied. The freshly calcined catalysts were characterized using BET surface area, XRD, FTIR, and H2-TPR techniques. On the other hand, Raman spectroscopy, TEM, XRD, and TGA analyses were performed for full characterization of the as-deposited carbon materials. The TPR and FTIR profiles of the fresh catalysts illustrated that the interaction between Co, Mo, and MgO increased by decreasing the Co/Mo ratio from 14.5 to 0.4. Also, the CoMo(6.5)/MgO catalyst displayed the highest surface properties compared to the other catalysts with different Co/Mo ratios. The CoMo(6.5)/MgO catalyst was the most active in terms of MWCNTs production. Moreover, the morphology, purity, and quality of the produced MWCNTs were strongly associated with the catalyst composition. TEM images illustrated that pure MWCNTs were obtained using the CoMo(14.5)/MgO catalyst, while a mixture of MWCNTs, carbon nanofibers (CNFs) and carbon nano-onions (CNOs) was produced using the CoMo(0.4)/MgO catalyst. Raman spectroscopy and TGA results proved that MWCNTs with the best quality and purity were obtained using the catalysts with Co/Mo ratios of 14.5 and 6.5.

One-Step Pyrolytic Synthesis of Multiwalled Carbon Nanotubes: The Role of Resupply of Carbon Species on the Quality Control.

An investigation on varying experimental parameters such as solution quantity (2.5, 5 and 7.5 mL) and reaction time (15, 30, 45 and 60 min) was carried out for the production of high-quality multiwalled carbon nanotubes (MWCNTs) in one step pyrolysis. Structural analysis revealed the uniform diameter distribution and the length of nanotubes in the range of 60-80 nm and 0.4-2 μm, respectively. Raman and X-ray diffraction analysis showed a remarkable reduction in defect density with increase in graphitization degree, upon increasing the solution volume and reaction time. MWCNTs prepared at higher solution quantity (7.5 mL) with higher reaction time (60 min) showed higher crystallinity (70% graphitization) and lower defect density (ID/IG: 0.56). The attainment in equilibrium of evaporation cum precipitation in formation of high quality nanotubes structure is evaluated. An effective resupplying of condensed precursors by re-evaporation leads for the achievement of low defect density nanotubes with higher product yield is achieved.

Proizvodnja višeslojnih ugljeničnih nanocevki polazeći od komercijalnih grafitnih olovaka korišćenjem pražnjenja električnog luka u vodenoj sredini

Carbon nanotubes (CNTs) are studied because of their diverse applications in many fields, such as medicine, computing, physics, chemistry, and others. Therefore, it is crucial to develop techniques for producing a large volume of high-quality multi-wall carbon nanotubes (MWCNTs) with the best cost-to-benefit ratio. In this paper, we obtain MWCNTs via an arc-electric alternative route, which dispenses catalysts and sealed cameras using water as an insulating medium. This method is simple, cost-effective (starting from pieces of commercial graphite pencil), efficient, and highly reproducible. Since no catalysts are used, no purification post-treatment was necessary, leading to high-quality MWCNTs. This technique is very promising for industrial applications because a lot of high-quality MWCNTs could be easily produced in a short time.

Nanocomposites Consisting of Carbon Nanotubes and Nanoparticles of Noble Metals

In the framework of the made researches nanocomposite of CNT-NPs type (Carbon Nanotube-Nanoparticles) consisting of multiwalled carbon nanotubes coated by rhodium nanoparticles and/or palladium using the two-step indirect method: chemical reduction have been produced. In the researches high-quality multi-walled carbon nanotubes MWCNTs with a length of 100 to 500 nm and a diameter of 8 to 20 nm previously obtained in the catalytic-chemical vapour deposition CCVD have been used. Nanotubes produced within the framework of own researches contain minor amounts of metallic impurities and amorphous carbon deposits. In order to deposit the noble metal nanoparticles on the surface of carbon nanotubes functionalization of multi-walled carbon nanotubes in a mixture of H2SO4 and HNO3 acids have been used. The prepared material has been subjected chemical reduction using noble metal precursors (RhCI3, PdCl2). The characterization of the produced material including the examination of the structure, morphology, chemical composition and evaluation of the size and distribution of rhodium and/or palladium nanoparticles on the surface of carbon nanotubes has been performed using: scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS). The produced nanomaterials may be used as the active layer of sensors of chemical/biological agents.

Development of sizing-free multi-functional carbon fibre nanocomposites

High quality multi-walled carbon nanotubes (CNTs) grown at high density using a low temperature growth method are used as an alternative material to polymer sizing and is utilised in a series of epoxy composites reinforced with carbon fibres to provide improved physical and electrical properties. We report improvements for sizing-sensitive mechanical and physical properties, such as the interfacial adhesion, shear properties and handling of the fibres, whilst retaining resin-infusion capability. Following fibre volume fraction normalisation, the carbon nanotube-modified carbon fibre composite offers improvements of 146% increase in Young’s modulus; 20% increase in ultimate shear stress; 74% increase in shear chord modulus and an 83% improvement in the initial fracture toughness. The addition of CNTs imparts electrical functionalisation to the composite, enhancements in the surface direction are 400%, demonstrating a suitable route to sizing-free composites with enhanced mechanical and electrical functionality.

High performance electrochemical H2O2 sensor based on MWCNT thin films fabricated by novel electron beam evaporation

High quality multi-walled carbon nanotubes (MWCNT) were grown by electron beam evaporation (EBE) under a high vacuum of 10−6mtorr. The influence of deposition thickness on the orientation, morphology and vibrational bands of MWCNT films fabricated on tantalum (Ta) substrate was discussed. XRD patterns of the film revealed the presence of (002) preferential plane of carbon. Raman spectral analysis show the G-band Raman feature corresponding to high frequency E2g of first order mode, suggesting that CNTs were composed of crystalline carbon. SEM image of 200nm thick MWCNT film shows well shaped homogenous fine nanotubes of length ~300nm and diameter ~70nm with high purity. The electrochemical performance of the MWCNTs/Ta electrodes was studied by cyclic voltammetry. The sensor prepared with optimum thickness can detect H2O2 in the wide range covering 5µM to 0.025mM, with the detection limit as low as 0.09µM. The results demonstrate that the fabrication of MWCNTs/Ta electrode by EBE is a very interesting and useful approach, likely to be a focus of upcoming research efforts in electrochemical sensing.

The MWCNTs-Rh Nanocomposite Obtained By The New High-Temperature Method

AbstractA nanocomposite was fabricated during the research undertaken, consisting of multiwalled carbon nanotubes coated with rhodium nanoparticles by the new high-temperature method being the subject of the patent claim. High quality multiwalled carbon nanotubes (MWCNTs) with the length of 100÷500 nm and the diameter of 8÷20 nm obtained in advance with Catalytic Chemical Vapour Deposition (CVD) were employed in the investigations. The nanotubes manufactured under the own research contain small amounts of metallic impurities and amorphous carbon deposits. Multiwalled carbon nanotubes functionalisation in acids was applied to deposit rhodium nanoparticles onto the surface of carbon nanotubes, and then the material was placed in a solution being a precursor of rhodium nanoparticles. The material prepared was next placed in a quartz vessel and subjected to high-temperature reduction in the atmosphere of argon to deposit rhodium nanoparticles onto the surface of multiwalled carbon nanotubes. The following examinations were performed, respectively: MWCNTs fabrication, fabrication of a CNT-NPs (Carbon NanoTube-NanoParticles) nanocomposite material; the characterisation of the materials produced including examination of the structure and morphology, and the assessment of rhodium nanoparticles distribution on the surface of carbon nanotubes. Micro- and spectroscopy techniques were employed to characterise the structure of the nanocomposites obtained.

Pyrolysis–Catalytic Reforming/Gasification of Waste Tires for Production of Carbon Nanotubes and Hydrogen

The production of high-value carbon nanotubes and hydrogen from the two-stage pyrolysis–catalytic reforming/gasification of waste tires have been investigated. The catalysts used were Co/Al2O3, Cu/Al2O3, Fe/Al2O3, and Ni/Al2O3. The pyrolysis temperature and catalyst temperature were 600 and 800 °C, respectively. The fresh catalysts were analyzed by temperature-programmed reduction and X-ray diffraction. The product gases including hydrogen were analyzed by gas chromatography, and the carbon nanotubes were characterized by scanning and transmission electron microscopy and Raman spectrometry. The results showed that the Ni/Al2O3 catalyst produced high-quality multi-walled carbon nanotubes along with the highest H2 yield of 18.14 mmol g–1 tire compared to the other catalysts, while the Co/Al2O3 and Cu/Al2O3 catalysts produced lower hydrogen yields, which is suggested to be associated with the formation of amorphous-type carbons on the surface of the Co/Al2O3 and Cu/Al2O3 catalysts.

Facile synthesis of high quality multi-walled carbon nanotubes on novel 3D KIT-6: application in high performance dye-sensitized solar cells.

A novel hard templating strategy for the synthesis of high quality multi-walled carbon nanotubes (MWCNTs) with a uniform diameter was developed. MWCNTs were successfully synthesized through chemical vapour deposition (CVD) using acetylene by employing 3D bicontinuous mesoporous silica (KIT-6) as a hard template and used as the counter electrode in dye-sensitized solar cells (DSSCs). Here, we report that Ni-Cr-KIT-6 and Co-Cr-KIT-6 systems are the most suitable catalysts for the growth of MWCNTs. Raman spectroscopy and TEM analysis revealed that the synthesized MWCNTs were of high quality and well graphitized. Impressively, DSSCs with a MWCNT counter electrode demonstrated high power conversion efficiencies (PCEs) of up to 10.53%, which was significantly higher than that of 9.87% obtained for a DSSC with a conventional Pt counter electrode. Moreover, MWCNTs had a charge transfer resistance (Rct) of only 0.74 Ω cm(2) towards the I3(-)/I(-) electrolyte commonly applied in DSSCs, which is several orders of magnitude lower than that of a typical Pt electrode (2.78 Ω cm(2)). These results indicate that the synthesized MWCNT counter electrodes are versatile candidates that can increase the power conversion efficiency (PCE) of DSSCs.

New ‘chimie douce’ approach to the synthesis of hybrid nanosheets of MoS2 on CNT and their anti-friction and anti-wear properties

Hybrid organic–inorganic oleylamine@MoS2–CNT nanocomposites with different compositions were obtained by thermal decomposition of tetrathiomolybdate in the presence of oleylamine and high quality multiwalled carbon nanotubes (CNTs) previously prepared by the CCVD technique. The nanocomposite samples were characterized by the TEM, SEM TG-MS, Raman and XRD techniques and successfully tested as anti-friction and anti-wear additives for grease lubricants.

Continuous and low-cost synthesis of high-quality multi-walled carbon nanotubes by arc discharge in air

We have developed a continuous and low-cost approach to prepare high-quality multi-walled carbon nanotubes (MWCNTs) using direct current arc discharge with a horizontal graphite anode and a vertical rotating cylindrical graphite cathode in air. The most important features of this promising process are continuously preparing nanotubes and simply adopting the cheapest and most accessible air as the buffer gas. When the cylindrical cathode rotates constantly, film-like MWCNT products are continuously deposited on the surface of cathode and immediately taken out of the arc discharge region by the rotating cathode. This process is quite favorable for the formation of nanotubes due to the easier condensation of carbon vapor quickly away from the arc region. Fine MWCNTs with random orientation can be obtained and they are nearly free of carbon nanoparticles and curved graphite sheet in them after simple purification at 750°C for 30min in air. The purified MWCNT film shows a good field emission property, and the open-on and threshold electric fields are 1.15V/μm and 1.66V/μm, respectively.

CHARACTERIZATION AND ELECTRICAL PROPERTIES OF ALIGNED CARBON NANOTUBES WITH HIGH ASPECT RATIO

High-quality multiwall carbon nanotubes (MWNTs) were produced by a simple one-step technique. The production of MWNTs was based on thermal decomposition of the mixture of a liquid phase organic compound and ferrocene. High degree of alignment was noticed by scanning electron microscopy. The aspect ratio of as-synthesized MWNTs was quite high (more than 4500). Transmission electron microscopy analysis showed the presence of the catalytic iron nanorods at various lengths of MWNTs. Raman spectroscopy was used to know the quality of MWNTs. The ratio of intensity of the G-peak to the D-peak was very high which revealed high quality of MWNTs. Magnetotransport studies were carried out at low temperature and a negative MR was noticed.

Investigation of water-assisted synthesis of high quality carbon nanotubes

Multiwall carbon nanotubes (MWNTs) were synthesized using a water-assisted method. High quality MWNTs having inner and outer diameter in the range of tens of nm and length in the range of hundreds of nm were obtained. The characterization results (SEM micrographs) clearly show that yield as well as nature (straight or twisted and curled) of produced carbon nanotubes varies directly with the diameter of initial carbon based precursor.