Development Of Multiwalled Carbon Nanotubes Research Articles

Development of multiwalled carbon nanotubes (MWCNT's) functionalized with molybdenum disulfide (MoS2) by separate methodology

Carbon nanotubes have considerable potential for many applications due to their unique physical and chemical properties. In this work, Multiwalled Carbon Nanotubes (MWCNT's) were synthesized by chemical vapor deposition and functionalized with molybdenum disulfide (MoS2) nanoparticles. The obtained nanostructures were characterized by SEM, TEM, Raman, XRD, XPS and TGA. Hybrid nanostructures of MWCNT's/MoS2 with stable MoS2 layer thickness of ~2 nm was obtained. The functionalized nanotubes showed variations in crystal structure, chemical composition, and thermal response with respect to the uncoated ones, so these structures are expected to have potential use in diverse engineering fields.

Effect of mixing protocol on the morphology development of multi-walled carbon nanotubes incorporated ternary blends of polycarbonate, styrene-acrylonitrile, and poly(methyl methacrylate) in a twin screw extruder

Effect of mixing protocol on the morphology development of multi-walled carbon nanotubes incorporated ternary blends of polycarbonate, styrene-acrylonitrile, and poly(methyl methacrylate) in a twin screw extruder

Development of multi-walled carbon nanotubes obtained from recycled plastics by single stage pyrolysis process

The development of nanofillers from plastic waste plays a significant role as an alternative plastic waste managing method. Multi-walled carbon nanotubes were produced by a single stage chemical vapor decomposition using polypropylene as carbon source in the presence of bimetallic catalyst. A mixture of Ar/H2 gas was used as a reducing agent for catalyst and at a later stage N2 was used to supply inert conditions for the pyrolysis product. Fe-Mn/Al2O3 catalyst was reduced at a temperature of 700 °C and PP waste was introduced at the same temperature to decompose at the surface of the catalyst to form the nanofillers. Tramission Electron Microscopy (TEM) and Raman characterization techniques were used to determine the properties of the nanofillers. The results showed that the developed nanofillers have a maximum diameter of 19.09 nm. TEM micrographs displayed lattice fringes at the magnitude of 20 nm indicating that the morphology of these nanofillers is crystalline. The Raman spectra showed the defect mode, D at the frequency of 1346 cm−1 and the tangential mode, G is at the frequency of 1588 cm−1. The intensity ratio ID/IG is 0,84 and signifies the quality of the nanofillers, as the ratio is the direct measure of the sample purity.The diameter obtained from the TEM analysis and the absence of the Radial Breathing Mode (RBM) on Raman spectra concluded that the nanofillers produced can be classified as Multi-Walled Carbon Nanotubes (MWCNT).

How do the mechanical properties of carbon nanotubes increase? An experimental evaluation and modeling of the engineering tensile strength of individual carbon nanotubes

To enable the development of multiwalled carbon nanotubes (MWCNTs) with superior mechanical properties, a theoretical model of the tensile strength of MWCNTs is developed, and the structural–mechanical property relationships of MWCNTs are investigated using experimental results obtained by uniaxial tensile tests from this study and data from the literature. We show that the nominal tensile strength is an important design factor in determining the mechanical properties of composites reinforced with carbon nanotubes (CNTs) and that the nominal (engineering) tensile strength is written as a product of the fracture strength (effective strength) and fracture cross-section ratio that can be calculated by the fracture cross-sectional area divided by the full cross-sectional area including the hollow core. Based on this model, controlling the degree of intershell crosslinking to produce clean break fractures in the nanotube shells without a dramatic degradation of the fracture strength is important for improving the nominal tensile strength.

Development of multi-walled carbon nanotubes modified pencil graphite electrode for the electrochemical investigation of aceclofenac present in pharmaceutical and biological samples

A sensitive and novel chemically modified multi-walled carbon nanotubes modified pencil graphite electrode (MCPGE) has been developed for the electrochemical investigation of aceclofenac (ACF). MCPGE was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Phosphate buffer solution (PBS) of pH7.0 was used as a suitable electrolytic medium, in which aceclofenac (ACF) exhibited a sensitive adsorption controlled oxidation peaks at +0.12, +0.32 and +0.51V and a reduction peak at −0.26V (vs Ag/AgCl). The experimental conditions were optimised by means of investigating the dependence of peak current on solution pH, concentration and scan rate etc. The electrochemical parameters such as surface concentration (Γ), electron transfer coefficient (α) and the standard rate constant (ks) were investigated at MCPGE. The oxidative peak currents were varied linearly with concentration in the range between 1×10−6 to 60×10−6M with a detection limit of 2.6×10−9M. The UV–Vis absorption spectrum of ACF gave the λmax at 272–273nm and is attributed to the presence of ACF. The applicability of the MCPGE was illustrated by the determination of ACF present in pharmaceutical and human urine samples.

MWCNT decorated V-doped titania: An efficient visible active photocatalyst

Highly photoactive metal oxide catalyst with efficient charge carrier separation can be developed using low-cost electron scavengers as an electron sink. Present work reports the development of Multiwalled Carbon Nanotube (MWCNT) decorated V-doped Titania (TiV) through sol-gel technique as an efficient visible active photocatalyst. MWCNT/TiV sample showed superior photocatalytic performance through 18 times enhancement in the rate constant compared to reference catalyst Degussa P25. TEM micrograph of the sample reveals the close bonding of TiV nanoparticles on the surface of MWCNT. The optical analyses confirm the extended and elevated absorption of the sample in visible range compared to the reference catalyst Degussa P25. The Raman spectra confirm the anatase/mixed phase of the sample and which is in agreement with the corresponding XRD and/or SAED data. The photocatalytic performance of the samples has been evaluated using methylene blue as probe pollutant. TiV (mixed) showed relatively high photocatalytic activity compared to MWCNT/TiV, TiV (anatase) and Degussa P25. The above results confirm that the optimized MWCNT/TiV (mixed) is expected to be a superior visible active low-cost photocatalyst for energy and environmental applications.

CVD Grown Mwcnts and Graphene for Pemfcs Application

In this paper we report the development of Multi-Walled Carbon Nanotubes (MWCNTs) and graphene via chemical vapor deposition (CVD) for PEM Fuel Cells applications. MWCNTs growth are achieved by the flow of ethylene and hydrogen gasses over iron beased catalytic substrates at different temperatures and gas flow. Graphene growth is carried out by the flow of methane and hydrogen gasses over various thickness cupper substrates cleaned by different methods (electropolishing, acetone and acetic acid) at low (500 mTorr) and atmospheric pressure. Characterization is performed with XRD, optical microscopy (SEM/EDS) and Raman/AFM spectroscopy. Results show noticeable differences in Raman signals and optical color contrast regarding the preferential growth of MWCNTs, and between the number and quality of layers of graphene and graphite, as well as distinctions between single-to-few- and multi-layer graphene, respectively. The electrochemical behavior of CVD grown MWCNTs and graphene are studied by cycling voltammetry on rotating disk electrode (RDE) to determine the activity of toward oxygen reduction reaction (ORR). Scanning Electrochemical Microscopy (SECM) is used to shows the localized electrochemical behavior difference between the MWCNTs and graphenes.

Development of Multi-Walled Carbon Nanotube and Processed Graphite Incorporated Hydraulically Bonded Refractory Castable

The incorporation of carbon materials is known to significantly enhance both corrosion and thermal shock resistance of refractories. For mixing and placement of refractory castables, water is the most suitable liquid media due to its availability, cost, non-hazardous characteristics and ease of handling. The main factors limiting the development and use of carbon-containing castables are the inferior wettability of carbon by water. Dispersion of carbon-containing materials in water with and without addition of surfactant was tested. By varying the carbon source and keeping the quality and quantity of all other raw materials constant, zero cement castable (ZCC) compositions were designed. The samples were coked and physical properties, oxidation resistance, and pore sizes were measured and FESEM studies carried out. The properties of castables containing processed graphite (PG) and multi-walled carbon nanotubes (MWCNT) were found to be most favourable for the iron and steel industry.

Multi-walled carbon nanotube–graphene–polyaniline multiphase nanocomposite with superior electromagnetic shielding effectiveness

The multiphase approach was adapted to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline (PANI) based nanocomposites. The natural graphite flakes (NGF) incorporated modified PANI was used for the development of multi-walled carbon nanotubes (MWCNTs) based nanocomposites. In PANINGF-MWCNTs composites, multilayer graphene was synthesized in situ by ball milling. The resultant PANINGF-MWCNTs nanocomposites were characterized by different techniques. It was revealed from the transmission electron microscope (TEM) observation that in situ derived multilayer graphene acts as a bridge between PANI and MWCNTs, and plays a significant role for improving the properties of multiphase nanocomposites. It was observed that EMI-SE increases with increasing the MWCNTs content from 1 to 10 wt% in the multiphase nanocomposites. The maximum value of total EMI-SE was -98 dB of nanocomposite with 10 wt% of MWCNTs content. The high value of EMI-SE is dominated by the absorption phenomenon which is due to the collective effect of increase in space charge polarization and decrease in carrier mobility. The decrease in carrier mobility has a positive effect on the shore hardness value due to the strong interaction between the reinforcing constituent in multiphase nanocomposites. As a consequence, shore hardness increases from 56 to 91 at 10 wt% of MWCNTs.

Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications

In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO4) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09±1.85MPa to 21.56±2.47MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials.

Development of multiwalled carbon nanotubes based micro-solid-phase extraction for the determination of trace levels of sixteen polycyclic aromatic hydrocarbons in environmental water samples

Micro-solid-phase extraction (μ-SPE) was developed for the determination of trace level of 16 United States Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) in river water samples with gas chromatography-mass spectrometry (GC-MS). In the μ-SPE device, multiwalled carbon nanotubes was employed as sorbent and was packed inside an porous polypropylene membrane "envelope" whose edges were heat-sealed to secure the contents. The μ-SPE device was placed in a stirred sample solution to extract the analytes. The porous polypropylene membrane envelope in μ-SPE device acts as a filter to exclude potential interferences, such as eliminating or reducing the influence of particles that are bigger than the pore size. After extraction, analyte desorption was carried out with a suitable organic solvent under ultrasonication. Important extraction parameters were optimized in detail, including the selection and amount of sorbent materials, the extraction temperature and extraction time, desorption solvent and desorption time, amount of organic modifier, agitation speed and sample ionic strength. Under the developed extraction conditions, the proposed method provided good linearity in the range of 0.1-50 μg/L, low limits of detection (4.2-46.5 ng/L), and good repeatability of the extractions (relative standard deviations, <12%, n=5). The developed μ-SPE method was successfully applied to the extraction of PAHs in river water samples. The μ-SPE method was demonstrated to be a fast and efficient method for the determination of PAHs from environmental water samples.

Sol–gel synthesis of multiwalled carbon nanotube-LiMn 2O 4 nanocomposites as cathode materials for Li-ion batteries

This study reports the development of multiwalled carbon nanotube (MWCNT)-LiMn 2O 4 nanocomposites by a facile sol–gel method. The elemental compositions, surface morphologies and structures of the nanocomposites are characterized with a view to their use as cathode materials for Li-ion batteries. The results indicate that the nanocomposite consists of LiMn 2O 4 nanoparticles containing undamaged MWCNTs. The nanocomposites show high cycle performance with a remarkable capacity retention of 99% after 20 cycles, compared with LiMn 2O 4 nanoparticles with a 9% loss of the initial capacity after 20 cycles. Measurements of a.c. impedance show that the charge-transfer resistance of the nanocomposites is much lower than that of spinel LiMn 2O 4. A cyclic voltammetry study further confirms higher reversibility of the nanocomposites compared with LiMn 2O 4 particles. The enhanced electrochemical performance of the nanocomposites is attributed to the formation of conductive networks by MWCNTs that act as intra-electrode wires, thereby facilitating charge-transfer among the spinel LiMn 2O 4 particles.

In Situ Cationic Ring-Opening Polymerization and Quaternization Reactions To Confine Ferricyanide onto Carbon Nanotubes: A General Approach to Development of Integrative Nanostructured Electrochemical Biosensors

This study demonstrates a new and relatively general route to the development of multiwalled carbon nanotube (MWNT)-based integrative electrochemical biosensors by confining ferricyanide redox mediator onto MWNTs. The ferricyanide-confined MWNTs are synthesized first through grafting of epoxy chloropropane onto MWNTs with in situ cationic ring-opening polymerization and then introducing the positively charged methylimidazolium moieties into the grafted polymer with a quaternization reaction. The grafted polymers with positively charged methylimidazolium moieties tethered onto MWNTs can essentially be used to confine redox-active ferricyanide onto MWNTs to form a redox mediator-confined nanocomposite with a good stability and excellent electrochemical property. The synthetic nanocomposite with surface-confined ferricyanide is demonstrated to be well-competent as the efficient electronic transducers for the general development of electrochemical biosensors upon combination with biorecognition units, which is illustrated by using glucose oxidase and laccase as two model biorecognition units. This study essentially paves a facile and general approach to the development of integrative nanostructured electrochemical biosensors.