Performance Of Multiwalled Carbon Nanotubes Research Articles

Mechanical behaviour of MWCNTs reinforced electrospun nanofibres

The nanoscale dimension of electrospun polymeric nanofibres produced by electrospinning are highly captivating, yet facing limitation of resisting external forces due to the weak tensile properties. Carbon nanotubes providing tremendous toughness due to extraordinary strong sp2 bonding network of carbon atoms in honeycomb lattice structure, augmented the physical resistant strength and is easily recover to its original state after load is removed. This study reports the performance of multi-walled carbon nanotubes (MWCNTs) as filler in the electrospinning of poly (L-lactide)-co-ε-caprolactone) (PLCL) composite nanofibres. Voltage of 10 kV is applied to the spinning solution mixture of 11 wt% (w/v) PLCL and MWCNTs, yielded nanofibres having diameters less than 400 nm. Results obtained showed the formation of composite nanofibres with tailored tensile behavior by modifying the content of MWCNTs. The addition of MWCNTs improved the tensile properties of resultant composite nanofibres, signified by tensile strength of 5.82 to 15.95 MPa, which were obtained using 0.1 to 1.0 wt% of MWCNTs. The structural integrity of nanofibres mats were retained in phosphate buffer saline (PBS) medium. Scanning Electron Microscopy (SEM) micrographs revealed the minimal of fiber deformation over 30 days of incubation and are closely identical to the initial diameter of as-spun fiber.

Low‐Cost Chitosan‐Derived N‐Doped Carbons Boost Electrocatalytic Activity of Multiwall Carbon Nanotubes

AbstractAn effective strategy is proposed to enhance the oxygen reduction reaction (ORR) performance of multiwall carbon nanotubes (MWCNTs) in both acid and alkaline electrolytes by coating them with a layer of biomass derivative N‐doped hydrothermal carbons. The N‐doped amorphous carbon coating plays triple roles: it (i) promotes the assembly of MWCNTs into a 3D network therefore improving the mass transfer and thus increasing the catalytic activity; (ii) protects the Fe‐containing active sites, present on the surface of the MWCNTs, from H2O2 poisoning; (iii) creates nitrogenated active sites and hence further enhances ORR activity and robustness.

Modeling of Joule Heating Induced Effects in Multiwall Carbon Nanotube Interconnects

Electrothermal performance of multiwall carbon nanotubes (MWCNT)-based interconnects has been studied under the influence of self-heating. The interlayer insulator is a low-k ( $\varepsilon _{r}\sim 2$ ) dielectric. Various geometries have been studied for the normal operation and breakdown conditions. Electrothermal coupled equations have been solved iteratively by solving Fourier heat diffusion equation with a finite-element method. Within the relaxation time approximation, mean free path of the electron has been calculated under different scattering mechanisms. Landauer–Buttiker formalism resistance has been used for calculating electrical resistance. Breakdown voltages for varying MWCNT lengths have been calculated and found to be higher in MWCNT with a shorter length. Breakdown voltage varies from 8.2 to 12 V for inner diameters 10–40 nm of 5- $\mu \text{m}$ interconnect length and 50-nm outer diameter. Breakdown voltage decreases with the increase in the length of interconnect. For a 5- $\mu \text{m}$ long interconnect, the breakdown voltage is nearly 8 V whereas for the same diameter $1~\mu \text{m}$ long interconnect it is nearly 22 V. Breakdown current density depends on the geometry $\vphantom {_{\int }} $ of the MWCNT and is estimated on the order of $10^{8}$ A $\cdot $ cm−2.

Study on electrochemical performance of multi-wall carbon nanotubes coated by iron oxide nanoparticles as advanced electrode materials for supercapacitors

Iron oxide was deposited on surface of multi-walled carbon nanotubes (Fe2O3@MWNTs) by atomic layer deposition (ALD). By a following calcination process, the electrochemical performance of the Fe2O3@MWNTs nanocompisites was further improved. From the X-ray diffraction and Raman spectra analysis of nanocomposites, Fe2O3 nanocrystallites were found to be successfully formed after a simple calcination process. The transmission electron microscopy revealed that Fe2O3 nanoparticles with the size of less than 10 nm are uniformly anchored on the surface of MWNTs. The X-ray photoelectron spectroscopy further confirmed that the valence state of iron in the composites is +3 and no other impurities were detected. The Fe2O3@MWNTs nanocomposites were investigated as electrode materials for high-performance supercapacitor. Electrochemical test results exhibited a high specific capacitance with 787 F g−1 at a discharge current density of 1 A g−1 and an outstanding rate performance (72% capacitance retention at 30 A g−1), and even after 5000 cycles the capacity retention was still maintained at 91.6%.

Effect of polymer type on characterization and filtration performances of multi-walled carbon nanotubes (MWCNT)-COOH-based polymeric mixed matrix membranes

ABSTRACTMulti-walled carbon nanotubes (MWCNTs) can be used for the fabrication of mixed matrix polymeric membranes that can enhance filtration perfomances of the membranes by modifying membrane surface properties. In this study, detailed characterization and filtration performances of MWCNTs functionalized with COOH group, blended into polymeric flat-sheet membranes were investigated using different polymer types. Morphological characterization was carried out using atomic force microscopy, scanning electron microscopy and contact angle measurements. For filtration performance tests, protein, dextran, E. coli suspension, Xanthan Gum and real activated sludge solutions were used. Experimental data and analyses revealed that Polyethersulfone (PES) + MWCNT-COOH mixed matrix membranes have superior performance abilities compared to other tested membranes.

Impact of tunneling conductance on the performance of multi walled carbon nanotubes as VLSI interconnects for nano-scaled technology nodes

Multi walled carbon nanotube (MWCNT) has received most of the attention for their unique characteristics as a possible alternative for copper as a VLSI interconnects for future integrated circuits. Multiple equivalent single-conductor circuit (ESC) models are reported in the literature for analysis of MWCNT as an interconnect, however most of them have neglected the impact of intershell tunneling conductance on the performance of MWCNT as interconnect. In this paper, a model is proposed for deriving equivalent impedance parameters by including tunneling conductance in order to study the impact of intershell tunneling conductance on the performance of MWCNT interconnect in terms of delay. Based on the derived equivalent impedance parameters, existing ESC model is modified. Further, the analytical and simulated results obtained from proposed model are compared with the results of existing models. It is revealed from the comparative analysis that the tunneling conductance has considerable impact on the impedance parameters and the propagation delay of an MWCNT bundle interconnect at variable interconnects length for nano-scaled technology nodes i.e. 32, 22 and 16 nm.

Functionalization of multi-walled carbon nanotubes with phenylenediamine for enhanced CO2 adsorption

The adsorption performance of multi-walled carbon nanotubes (MWCNTs) towards CO2 gas was enhanced by covalently grafting of phenylenediamine (PDA) via an activation-grafting process. Different loading amounts were achieved by changing the activation time and the dosage of activating agent. The so-synthesized adsorbents were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Thermogravimetry analysis, Transmission electron microscope, Raman spectroscopy and Nitrogen adsorption–desorption analysis. The CO2 adsorption properties were studied via static volumetric method. The results indicated that the modification process did not alter the crystal structure, whilst the quantity of defect sites and amorphous structures increased greatly. Moreover, the average pore size after functionalization increased from 9.68 to 23.80 nm. 0.59 mmol·g−1 of CO2 were captured by aminated MWCNTs at 303.15 K and 200 kPa, while the adsorption capacity of the raw materials was only 0.17 mmol·g−1 under the same conditions. Adsorption–regeneration cycles exhibited the stability of the PDA modified MWCNTs during the prolonged cyclic operations. We found that the adsorption of CO2 on MWCNTs belonged to physical adsorption and the adsorption behavior of CO2 on PDA modified MWCNTs was a chemical adsorption. The effective enhancement of the CO2 capture ability was attributed to the increased number of active sites, which offered stronger interactions with CO2 after PDA grafting.

Experimental investigation of MWCNT–water nanofluids flow and convective heat transfer characteristics in multiport minichannels with smooth/micro-fin surface

This paper reports on the results of an experimental study on the heat transfer and flow performance of multiwalled carbon nanotubes (MWCNT) in aqueous suspensions flowing in multiport minichannel flat tubes with smooth/micro-fin surface under a constant heat flux condition. The MWCNT–water nanofluids volume concentrations are 0.001%, 0.005%, 0.01%, and 0.1%. Results indicate that the friction factor and the Nusselt number of the nanofluids are higher than those of water. The Nusselt number does not increase with volume concentration. The heat transfer of nanofluids in the micro-fin tubes is higher than that of nanofluids in the smooth tube. However, the heat transfer enhancement of nanofluids in the micro-fin tubes is lower than that of nanofluids in the smooth tube. The effect of micro-fin spacing is more evident in nanofluids than in water. Nanofluids with a concentration of 0.01% flowing in the tube with closely spaced micro-fin tube exhibit the optimal thermal performance in accordance with the performance evaluation criterion.

Experimental study on the heat transfer of MWCNT/water nanofluid flowing in a car radiator

This study is concerned with an experimental evaluation of the thermal performance of multi-walled carbon nanotubes (MWCNT) dispersed in distilled water flowing inside an automotive radiator. A two-step method called high-pressure homogenization was used to disperse the MWCNT nanoparticles in water, in concentrations varying between 0.05 and 0.16wt%. Experiments have been carried out in an experimental set up composed by a wind tunnel that simulates the air flow through a car radiator, and a hot fluid circuit, that circulates the nanofluid inside the radiator. The air flow rate was maintained constant at 0.175kg/s. The mass flow rate of the hot fluid varied from 30 up to 70g/s and the inlet temperature was maintained constant at 50, 60, 70 and 80°C, respectively. The temperature drop and heat transfer rate have been investigated. A slight-decrease on the heat transfer rate, up to 5%, was found for all test conditions. On the other hand as the nanoparticle concentration increased, the heat transfer rate decreased.

Effect of Pretreatment on Physicochemical Properties and Performance of Multiwalled Carbon Nanotube Supported Cobalt Catalyst for Fischer–Tropsch Synthesis

The influence of different nitric acid concentrations (35, 50, 70 wt %) on the physicochemical properties of multiwalled carbon nanotube was investigated. 15 wt % cobalt was impregnated on acid treated nanotubes. The corresponding catalysts were characterized by BET, XRD, Raman, SEM, TEM, TPR, CO chemisorption techniques to further study the impact of acid functionalization on textual properties, metal dispersion, crystallite size, defect generation, and reducibility of 15Co/CNT catalysts. The performance of prepared catalysts was tested for 30% CO and 60% H2 with balanced Ar in a fixed bed microreactor for Fischer–Tropsch synthesis at 220 °C, 2 MPa, and GHSV of 3000 cm3·g–1·h–1. Pretreatment of CNTs with 70 wt % nitric acid exhibited improved physicochemical properties of 15Co/CNT catalyst and hydrocarbon yield by 35% as compared to untreated CNT supported catalyst.

Electrocatalytic performances of multi-walled carbon nanotubes chemically modified by metal phthalocyanines in Li/SOCl2batteries

​A series of metal 2,9,16,23-tetraaminophthalocyanines have been prepared and used to chemically modify fluorinated multi-walled carbon nanotubes (F-MWCNTs). The modified F-MWCNTs can dramatically improve the capacity of the Li/SOCl2battery.

Effect of wrinkles on electrochemical performance of multiwalled carbon nanotubes as anode material for Li ion battery

A 1-D monohybrid of multiwalled carbon nanotubes and graphene sheets, graphene wrapped multiwalled carbon nanotubes (gC) structure, synthesized in a template-free simple chemical vapor deposition technique without any chemical functionalization, was employed as efficient anode material for Li ion battery. Graphene nanosheets affixed to the multiwalled carbon nanotubes (MWNTs) surface by van der Waal's attraction gives a wrinkled surface to the final 1-D gC configuration. The protrusions on the surface of the tube enhances the porosity of the system and also acts as defects, enhancing lithium adsorption sites while the inner MWNT core gives high electrical conductivity, resulting enhanced electrochemical performance of 373mAhg−1 at 100mAg−1 current density after 150 cycles.

Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g−1 at C/10. Also, it exhibits 89 mAh g−1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

Hexagonal boron nitride (h-BN) nanoparticles decorated multi-walled carbon nanotubes (MWCNT) for hydrogen storage

Hydrogen is considered as the most promising clean energy carrier because of its abundance, environmental friendliness and high conversion efficiency. However, developing safe, compact, light weight and cost-effective hydrogen storage materials is one of the most technically challenging barriers to the widespread use of hydrogen as fuel. The present work reports the hydrogen storage performance of multi-walled carbon nanotubes (MWCNT)/hexagonal boron nitride (h-BN) nanocomposites (MWCNT/h-BN), where ultrasonication method is adopted for the synthesis of the MWCNT/h-BN nanocomposites. Hydrogenation process was carried out using Seiverts-like hydrogenation setup. Characterization techniques such as X-ray Diffraction (XRD), Micro-Raman Spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Nitrogen adsorption–desorption isothermal studies (BET), CHN-elemental analysis and Thermogravimetric Analysis (TGA) were used to analyze the samples at various stages of the experiment. A maximum of 2.3 wt% hydrogen storage is achieved in the case of acid treated MWCNTs (A-MWCNT) with 5 wt% of h-BN nanoparticles compared to pure MWCNTs that could store 0.15 wt% only. Moreover the calculated binding energy (0.42 eV) of stored hydrogen of A-MWCNT with 5 wt% of h-BN nanocomposite lies in the recommended range of binding energy (0.2–0.6 eV) for fuel cell applications. The TG study shows that 100% desorption is achieved at the temperature range of 120–410 °C and confirms that the prepared hydrogen storage medium will serve effectively in the realm of hydrogen fuel economy in near future.

Effects of NH3 PECVD treatment time on the performance of multiwall carbon nanotubes for antibody immobilization.

This work presents an amino plasma-enhanced chemical vapour deposition (NH3 PECVD) treatment to modify multiwall carbon nanotubes (MWCNTs) for the immobilization of antibodies (IgG-gold), and the effects of treatment time were studied. A titanium nitride (TiN) buffer layer and a nickel catalyst layer were deposited on silicon substrates for synthesis of MWCNTs using thermal CVD. The MWCNTs were modified by amine (NH2 (-) ) or amino (NH(-) ) functional groups for 1, 3, and 5 min by PECVD, respectively. Mouse IgG-golds were immobilized on the modified MWCNTs using glutaraldehyde (GA) as a crosslinker. The performance of the modified MWCNTs was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR), contact angle system (CA), X-ray photoelectron spectroscopy (XPS, ESCA), and UV-visible spectroscopy. Results show that the efficiency of IgG-gold immobilization was increased with the increase of NH3 PECVD treatment time. The NH3 PECVD treatment changed the surface properties of the MWCNTs, tuning them more hydrophilic without affecting their structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1343-1351, 2016.

Influence of temperature on MWCNT bundle, SWCNT bundle and copper interconnects for nanoscaled technology nodes

This paper presents the comparative analysis of temperature dependent performance of Multi-walled carbon nanotubes (MWCNT), Single-walled carbon nanotube (SWCNT) and copper interconnects for nanoscaled technology nodes. The temperature dependent impedance circuit model is proposed for MWCNT bundle interconnects. The proposed model for MWCNT bundle shows the various electron–phonon scattering mechanisms dependency as a function of temperature. The performance in terms of propagation delay, power dissipation and power delay product for MWCNT bundle interconnects is simulated on the basis of temperature dependent electrical parameters for global interconnects at three different technology nodes viz. 32, 22 and 16 nm for temperature range 200 to 450 K. A similar analysis is performed for SWCNT bundle and copper interconnects and results are compared with the MWCNT bundle interconnects. The comparative results revealed that the performance of MWCNT bundle interconnects is better than the performance of SWCNT bundle and copper interconnects at different temperature ranging from 200 to 450 K for 32, 22 and 16 nm technology nodes at global interconnects.

Determination of multi-pesticide residue in tobacco using multi-walled carbon nanotubes as a reversed-dispersive solid-phase extraction sorbent.

A multi-pesticide residue determination method based on a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method using multiwalled carbon nanotubes as reversed-dispersive solid-phase extraction material was validated in 37 representative pesticides in tobacco. Determination was performed using liquid chromatography with tandem mass spectrometry in multiple reaction monitoring mode. Three major types of tobacco leaf samples, namely, flue-cured, burley, and oriental tobacco were studied and compared. Three factors (extraction time, external diameter, and amount of extraction material used) that could affect the performance of multi-walled carbon nanotubes were investigated. Optimization of sample preparation and determination allowed recoveries between 70.8 and 114.8% for all 37 pesticides with < 20.0% relative standard deviations at three spiking levels of 20, 50, and 200 μg/kg. The limits of quantification and limits of detection for the 37 pesticides ranged within 0.46-28.57 and 0.14-8.57 μg/kg at a signal-to-noise ratio of 10 and 3, respectively.

Enhanced Rate Capability of Polymer-Derived SiCN Anode Material for Electrochemical Storage of Lithium with 3-D Carbon Nanotube Network Dispersed in Nanoscale.

Electrochemical performances of multi-walled carbon nanotubes (CNT)-SiCN composite have been investigated. The sample was synthesized by a simple ultrasonication assisted method combined with high-temperature pyrolysis and characterized by Fourier transform infrared spectra, Raman spectra, X-ray diffraction, field emission scanning electron microscopy and transmission electronic microscopy. In this composite, CNT were uniformly distributed in the SiCN ceramic matrix, it retained the structural integrity during the polymer-ceramic conversion and had a relatively strong bonding with the SiCN ceramic matrix. When tested as anode in the half cell, the obtained composite exhibited enhanced rate capability and cyclic capacity than that of pristine SiCN powder, CNT and graphite, it could supply a capacity of 222.7 mA h/g when charged at 2000 mA/g, while the SiCN anode showed nearly no capacity even at the low current density of 200 mA/g. It is expected that the CNT-SiCN composite, perhaps the series of CNT-PDC composites, may be prospective candidate for high power applications.

Adsorption performance of multiwall carbon nanotubes and graphene oxide for removal of thiophene and dibenzothiophene from model diesel fuel

Multiwall carbon nanotubes (MWCNT) and graphene oxide (GO) are promising compressible nano adsorbents that can be used in the deep desulfurization process for mobile applications. In this study, the adsorption isotherm and the adsorption kinetics of thiophene and dibenzothiophene (DBT) introduced in hexane as a model diesel fuel have been investigated. The adsorption performance of thiophene and DBT on MWCNT and GO were compared with the adsorption performance on activated carbon (AC) as a reference material. In addition, the effect of agitation speed and adsorbent dosage amount were studied. The DBT adsorption results on the three adsorbents were represented by Langmuir and Freundlich isotherm models. The Freundlich isotherm was found to be more favorable with squared correlation coefficient (R 2) >0.97. The thiophene adsorption isotherm was fitted only by the Freundlich isotherm model with R 2 > 0.989. The adsorption rate for these sulfur compounds follows the pseudo-second-order adsorption kinetic. The removal efficiency of DBT using the MWCNT was 68.8 % almost twice the GO removal efficiency but lower than the AC removal efficiency by about 25 %. In addition, the ability of these adsorbents to remove the DBT from the model fuel was much higher than their capability to remove the thiophene.

Oil Adsorption and Reuse Performance of Multi-Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) have aroused widespread attention as a new type of adsorbents due to their outstanding ability for oil adsorption. In this work, the effects of recycling method, different types oil, metal ions and surfactants on the adsorption capacity and reuse performance of MWCNTs were investigated. The results showed that with the increase of the number of reuse, oil adsorption ability of MWCNTs decreased and stabilized gradually. Through the study on the methods of oil removing from MWCNTs and re-adsorption performance of MWCNTs, it was found that the re-adsorption capacity of incinerated MWCNTs is higher than those extruded ones. This may due to the destruction of the gap between carbon nanotubes during the extrusion process, which leading to lower oil adsorption capacity. The oil adsorption capacity on the extruded MWCNTs increased with the increase of carbon chain length of the oil, while that on the incinerated ones decreased. With the existing of mental ions and surfactant, it was found that the oil adsorption capacity increased with the increasing of ions and surfactant concentration.