Hybrid Multi-walled Carbon Research Articles

Synergistic Effect of CNT-TiO2 Catalyst and 3D Electrode Architecture for Electrochemical Performance in Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are a potential electrochemical storage system for the future with high capacity (1675 mAh g−1) and energy density (∼2600 Wh kg−1). The poor conductivity of sulfur, polysulfide shuttle effect, and volume expansion of the sulfur cathode are the main hurdles to their commercialization. To mitigate these issues, this work represents a rational composite of hybrid multiwalled carbon nanotubes (MWCNT) -TiO2 high surface area carbon-sulfur composite (CTHS) onto a 3D carbon fiber (CF) based free-standing electrode (CTHS@CF) architecture. TiO2 can effectively anchor the polysulfides by chemical bonding and improve cyclability. MWCNTs and CFs are the effective electron transport materials that accelerate the redox kinetics of polysulfides. The electrochemistry of CTHS@CF reveals an excellent discharge capacity of 910 mAh g−1 (1st cycle) at 100 mA g−1 compared to the conventional aluminum-coated (CTHS@Al) of 532 mAh g−1. The CTHS@CF (at 300 mA g−1) displays 514 mAh g−1 (initial discharge) capacity with 83% capacity retention up to 100 cycles, whereas CTHS@Al shows 394 mAh g−1 with 44% capacity retention. Combining 3D electrode architecture with the metal oxide (TiO2) plays a vital role in the electrochemistry of LSBs by improving the stability of the battery’s cycle life and overall energy density.

Shape memory properties of epoxy with hybrid multi-walled carbon nanotube and montmorillonite nanoclay nanofiller

Shape memory properties of epoxy with hybrid multi-walled carbon nanotube and montmorillonite nanoclay nanofiller

Covalent functionalization of hybrid multi-walled carbon nanotube-graphene with polyethileneglycol for targeted delivery of Temozolomide

Covalent functionalization of hybrid multi-walled carbon nanotube-graphene with polyethileneglycol for targeted delivery of Temozolomide

Pristine, carboxylated, and hybrid multi-walled carbon nanotubes exert potent antioxidant activities in in vitro-cell free systems

Multi-walled carbon nanotubes (MWCNTs) are tubular-shaped carbon allotropes, composed of multiple concentric graphene cylinders. The extended systems of conjugated double bonds, that MWCNTs are constituted by, provide them with high electron affinities, enabling them to act as electron donors or acceptors. Consequently, their potential biomedical applications, as synthetic antioxidant agents, are of particular interest. Based on the above, the purpose of the present study was to evaluate the intrinsic antioxidant properties of pristine and carboxylated MWCNTs, as well as of novel hybrid nanocomposites of MWCNTs and inorganic nanoparticles. To this end, after the synthesis and characterization of MWCNTs, their antiradical, reducing, and antigenotoxic properties were assessed in cell-free assays, using a methodological approach that has been recently proposed by our research group. According to our results, most of the tested MWCNTs exhibited strong antioxidant activities. More elaborately, the hybrid material of MWCNTs and ferrous oxide nanoparticles, i.e., CNTs@Fe3O4, showed robust scavenging capacities in all free-radical scavenging assays examined. As regards reducing properties, the pristine MWCNTs, i.e., CNTs-Ref, exhibited the greater electron donating capacity. Finally, in terms of antigenotoxic properties, the hybrid material of MWCNTs and silicon carbide nanoparticles, i.e., CNTs@SiC, exhibited potent ability to inhibit the formation of peroxyl radicals, thus preventing from the oxidative DNA damage. Conclusively, our findings suggest that the MWCNTs of the study could be considered as promising broad-spectrum antioxidants, however, further investigations are required to evaluate their toxicological profile in cell-based and in vivo systems.

Preparation of Hybrid Multi-Walled Carbon Nanotubes (Mwcnts)-Polymer Films on Top of Micro-Interdigitated Electrodes for the Selective Detection of Volatile Organic Compounds At Room-Temperature

Preparation of Hybrid Multi-Walled Carbon Nanotubes (Mwcnts)-Polymer Films on Top of Micro-Interdigitated Electrodes for the Selective Detection of Volatile Organic Compounds At Room-Temperature

Effect of hybrid multi-walled carbon nanotube and montmorillonite nanoclay content on mechanical properties of shape memory epoxy nanocomposite

In this study, the hybrid nanofiller of montmorillonite (MMT) and multi-walled carbon nanotube (MWCNT) were incorporated into shape memory epoxy (SMEP) at different loadings. The fillers were dispersed in the SMEP resin by sonication. Tensile and flexural properties were analyzed at room temperature (RT) and high temperature (HT). Field emission scanning electron microscopy (FE-SEM) was used to analyze the microstructure of fractured samples. The tensile results revealed that at RT, the hybrid filler nanocomposite exhibits a ductile behavior meanwhile at HT, the nanocomposite exhibits a brittle behavior. The sample with the hybrid filler loading of 3 wt% MMT and 1.0 wt% MWCNT produced maximum performance with an increase of 32.5% in the ultimate tensile strength (UTS) and 20.9% in Young’s modulus at RT. The trends of the UTS and modulus obtained in the HT tensile test were almost similar to the RT tensile test despite yielding lower value. The RT flexural test revealed an increasing flexural strength as the filler loading increased with a maximum of 176% increase for hybrid filler of 3 wt% MMT and 1.0 wt% MWCNT. This trend was also observed for the flexural strength at HT. From FE-SEM, it was observed that the SMEP nanocomposite containing 3 wt% MMT and 1.0 wt% MWCNT was well dispersed and interact with each other, producing a synergetic reinforcement towards the performance. This study demonstrates the tensile and flexural reinforcement effect of MMT and MWCNT hybrid nanofiller. Findings from this study can be utilized to select the optimum loading for mechanical requirements in various applications.

Development of low-cost hybrid multi-walled carbon nanotube-based ammonia gas-sensing strips with an integrated sensor read-out system for clinical breath analyzer applications

This work demonstrates the development of Ag@polyaniline/multi-walled carbon nanotube nanocomposite-based sensor strips and a suitable integrated electronic read-out system for the measurement of trace-level concentrations of ammonia (NH3). The sensor is optimized under various operating conditions and the resulting sensor exhibited an enhanced response (32% for 2 ppm) with excellent selectivity. Stable performance was observed towards NH3 in the presence of high concentrations of CO2 (>40 000 ppm), simulated and real breath samples. A suitable electronic sensor read-out system has also been designed and developed based on multi-scale resistance-to-voltage conversion architecture, processed by a 32-bit microcontroller which is operatable over a wide range of sensor resistance (1 kΩ to 200 MΩ). As a proof of concept, integration of gas-sensing strips with the electronic read-out system was tested with various levels of NH3 (<2 ppm as normal, >2 ppm as critical and 2 ppm as threshold), which is important for clinical breath analyzer applications. The developed prototype device can be readily incorporated into a portable, low-cost and non-invasive point-of-care breath NH3 detection unit for portable pre-diagnostic breath analyzer applications.

Kinetic study of MWCNT and MWCNT@P3HT hybrid thermal decomposition under isothermal and non-isothermal conditions using the artificial neural network and isoconversional methods

Development of new hybrid multi-walled carbon nanotubes (MWCNT) and conducting polymer has been studied due to these materials versatility. The knowledge of thermal properties is essential to evaluate the hybrids applicability, mainly in optoelectronic devices. In this work, chemical modifications was performed on the surface of MWCNT through microwave reaction, due to a shorter reaction time, less use of organic solvents and thionyl chloride free (high toxicity reagent). Subsequently, a new hybrid MWCNT@P3HT was obtained by in situ polymerization of poly (3-hexylthiophene) in the modified MWCNT, covalently linked. Kinetic study of thermal degradation was performed employing artificial neural network and isoconversional treatment, Friedman (FR) and Vyazovkin methods. The activation energies of MWCNT and MWCNT@P3HT thermal decomposition were determined and showed a significant increase in thermal stability for the hybrid. The activation energy for the MWCNT@P3HT is almost four times greater than the pure one, around 454.9 kJ mol−1.

Synergistic effects of hybrid MWCNT/nanosilica on the tensile and tribological properties of woven carbon fabric epoxy composites

An epoxy matrix incorporated with hybrid multi-walled carbon nanotube (MWCNT) and nanosilica was used to fabricate woven carbon fabric epoxy composites using vacuum-assisted resin infusion molding (VARIM). Three types of multi-scale hybrid composites containing 0.2 wt.% MWCNT + 0.7 wt.% nanosilica, 0.7 wt.% MWCNT + 0.2 wt.% nanosilica, and 0.45 wt.% MWCNT + 0.45 wt.% nanosilica were prepared to investigate both tensile and tribological properties, simultaneously. The results of tensile and tribological experiments showed that specimens containing 0.45 wt.% MWCNT + 0.45 wt.% nanosilica were better than the corresponding single-type nanoparticles with the same total weight percentages. Especially, the tensile strength and tensile modulus of composite specimens containing 0.45 wt.% MWCNT + 0.45 wt.% nanosilica increased by 25.2% and 31% in comparison with the neat composites, while their friction coefficient and wear rate decreased by 88% and 98% in comparison with the neat composites, respectively. The SEM images of fracture surfaces showed that the incorporation of nanoparticles enhanced the fiber–matrix interfacial strength, toughened the surrounding matrix, and improved resin adhesion to the fiber, which increased tensile properties of incorporated composites with hybrid nano-fillers. Moreover, by adding the hybrid nanoparticles to the unfilled carbon fabric composites, the friction coefficient variation of these specimens totally changed, which led to an improvement in the friction-reducing ability and wear rate resistance. In conclusion, a method is suggested in this paper to incorporate hybrid nanoparticles for benefitting from the properties of both nanoparticles at higher weight percentages.

Highly Stretchable Micro‐Supercapacitor Arrays with Hybrid MWCNT/PANI Electrodes

Stretchable energy storage devices are required to fit for stretchable electronic devices, forming a fully stretchable system for comfortable and body‐attachable electronic devices. Herein, highly stretchable micro‐supercapacitors are fabricated by designing wave‐shaped hybrid multiwalled carbon nanotubes/polyaniline electrodes. As‐fabricated stretchable devices exhibit a large areal capacitance of 44.13 mF cm−2 and offer a power density of 0.07 mW cm−2 at an area energy density of 0.004 mW h cm−2. Owing to the designed wavy electrode structure, the electrochemical performances of the stretchable micro‐supercapacitors are almost invariably under different stretching stations ranging from 5% to 40%. By fabricating stretchable micro‐supercapacitors arrays, a red light‐emitting diode can be easily lighted under different conditions including stretching, twisting, crimping, and winding. All these results confirm the outstanding stability and mechanical strength of stretchable micro‐supercapacitors, demonstrating its potential application in skin‐patchable electronics or portable/wearable devices.

A novel sandwich-type immunosensor for detection of carcino-embryonic antigen using silver hybrid multiwalled carbon nanotubes/manganese dioxide

A novel sensitive sandwich-type nonenzymatical electrochemical immunosensor was fabricated for quantitative determination of the carcino-embryonic antigen (CEA). β-cyclodextrin/multiwalled carbon nanotubes (β-CD/MWCNTs) that were used as electrochemical sensing platform improved the surface of electrode to immobilize first antibodies (Ab1) and enhanced the electrical conductivity. The synthetic silver nanoparticles-carbon nanotube/manganese dioxide (Ag NPs-MWCNTs/MnO2) was used as labels of secondary antibodies (Ab2) can improve the surface of electrode and enhance the electrochemical signal. MnO2 and Ag NPs achieve dual signal amplification to improve the sensitivity effectively. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.0001–0.5ng·mL−1 and 0.5–10ng·mL−1 respectively with a low detection limit of 0.03pg·mL−1 for CEA. The immunosensor was also successfully applied to detect the actual sample. This novel method may find huge potential application for the detection of CEA in the clinical diagnosis.

A sandwich-type electrochemical immunosensor based on multiple signal amplification for α-fetoprotein labeled by platinum hybrid multiwalled carbon nanotubes adhered copper oxide

In this work, we designed a novel and ultrasensitive sandwich-type electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP), using β-cyclodextrin functionalized graphene (CD-GS) as the platform and platinum hybrid multiwalled carbon nanotubes adhered copper oxide (Pt@CuO-MWCNTs) as labels. CD-GS has high specific surface area, ideal dispersibility and good biocompatibility, which was used to efficiently capture more primary antibodies (Ab1). Pt, CuO and multiwalled carbon nanotubes (MWCNTs) can be used as catalysts for the decomposition of hydrogen peroxide. The Pt@CuO-MWCNTs realized multiple amplified signals due to their synergy. Therefore, Pt@CuO-MWCNTs was used as the marker, combined with secondary antibodies (Ab2) and this has the effect of multiple amplified signals to catalyze hydrogen peroxide. Under optimal conditions the designed immunosensor exhibited a wide linear range from 1pgmL−1 to 20ngmL−1 with a low detection limit of 0.33pgmL−1 (S/N=3) for AFP. The designed immunosensor showed good selectivity, reproducibility and stability, which could provide potential applications in clinical monitoring of AFP.

Free-binder lithium ion battery based on a hybrid multiwalled carbon nanotube-graphitic platelet architecture

We have developed a novel material with a hybrid multiwalled carbon nanotube–graphitic platelet architecture for lithium ion battery (LIB) anode that requires no additional aggregate and support materials such as polymeric binders and current collectors of copper or aluminum foils. The absence of these inhomogeneous additives signifies a weight increase of the anode active materials, which contributes to charge-discharge capacities and gives rise to increasing energy densities. The as-prepared materials were characterized by scanning electronic microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical measurements. Results reveal that these hybrid architecture materials with multiwalled carbon nanotubes (MWCNTs) and layered and honeycombed graphitic platelets not only show excellent performance as LIB electrode material but also lower the manufacturing costs.

Hybrid multiwalled carbon nanotube − Laponite sorbent for removal of methylene blue from aqueous solutions

The article discusses adsorption of methylene blue dye by novel hybrid sorbent consisting of Laponite and multiwalled carbon nanotubes. The sorbent was obtained by sonication of the aqueous suspensions of nanotubes at different concentrations of Laponite. The methods of the methylene blue adsorption, dead-end membrane filtration and environmental scanning electron microscopy were used for the sorbent characterization.It may be concluded from the results of filtration and adsorption experiments that sonication of mixed aqueous suspensions of Laponite and multiwalled carbon nanotubes leads to the formation of hybrid particles (ML-particles) with a core–shell structure. The size and the shape of hybrid particles were determined by nanotubes, while their adsorption properties were determined by Laponite particles attached to the surface of nanotubes. The Laponite content in hybrid particles was corresponding to the Laponite to nanotubes ratio in the initial suspension XL=0–1.Due to the presence of Laponite in the sorbent, its adsorbing capacity was much higher as compared to the adsorbing capacity of pure nanotubes, and it was directly proportional to the Laponite content. This sorbent may be used either as a purifying additive or as a filtering layer if it is deposited on the surface of a supporting membrane. Due to relatively large size of hybrid particles, they can be easily separated from the purified solution by filtration or centrifugation.

High electrical conductivity of nylon 6 composites obtained with hybrid multiwalled carbon nanotube/carbon fiber fillers

ABSTRACTThe synergetic effect of multiwalled carbon nanotubes (MWNTs) and carbon fibers (CFs) in enhancing the electrical conductivity of nylon 6 (PA6) composites was investigated. To improve the compatibility between the fillers and the PA6 resin, we grafted γ‐aminopropyltriethoxy silane (KH‐550) onto the MWNTs and CFs after carboxyl groups were generated on their surface by chemical oxidation with nitric acid. Fourier transform infrared spectroscopy and thermogravimetric analysis proved that the KH‐550 molecules were successfully grafted onto the surface of the MWNTs and CFs. Scanning electron microscopy and optical microscopy showed that the obtained modified fillers reduced the aggregation of fillers and resulted in better dispersion and interfacial compatibility. We found that the electrical percolation threshold of the MWNT/PA6 and CF/PA6 composites occurred when the volume fraction of the fillers were 4 and 5%, respectively. The MWNT/CF hybrid‐filler system exhibited a remarkable synergetic effect on the electrically conductive networks. The MWNT/7% CF hybrid‐filler system appeared to show a second percolation when the MWNT volume fraction was above 4% and a volume resistivity reduction of two orders of magnitude compared with the MWNT/PA6 system. The mechanical properties of different types of PA6 composites with variation in the filler volume content were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40923.

Hybrid multi-walled carbon nanotubes-alginate-polysulfone beads for adsorption of bisphenol-A from aqueous solution

In recent years, the potential application of carbon nanotubes (CNTs) as sorbent materials in wastewater treatment has garnered tremendous attention. Concerns that CNTs may be toxic to living organism, however, necessitate that the containment of CNTs to prevent their release into the environment in order to realize their practical application in wastewater treatment. In this study, we immobilized multi-walled carbon nanotubes (MWCNTs) within macro-calcium alginate beads. The composite beads were coated with an additional polysulfone (Psf) layer both to provide an external barrier to MWCNTs release into the effluent and also to improve the mechanical integrity of the beads. The hybrid beads were tested for their capacity to remove the bio-refractory endocrine disruptor compound bisphenol-A (BPA) using batch and packed bead column experiments. Maximum BPA removal was achieved at 22% MWCNTs, which was the dispersion limit of MWCNTs in our study. The adsorption of BPA followed Langmuir isotherm model with good correlation. The maximum adsorption capacity of the composite beads of dosage 4 g L−1 as obtained using the Langmuir model was 24.69 mg g−1. Addition of the Psf layer, together with MWCNTs, improved the bead compression performance by up to twelvefold at 40% compressive extension. This study showed that the hybrid alginate-Psf bead may serve as compartment for encapsulation of MWCNTs for removal of BPA. Improved compression performance introduced by addition of Psf layer could protect hybrid beads used, for example, in reactors subjected to extreme conditions such as high flow rates.

Synthesis, characterization, and dye sorption ability of carbon nanotube–biochar nanocomposites

Innovative technologies incorporating engineered nanoparticles into biochar production systems could improve the functions of biochar for many applications including soil fertility enhancement, carbon sequestration and wastewater treatment. In this study, hybrid multi-walled carbon nanotube (CNT)-coated biochars were synthesized by dip-coating biomass in varying concentrations of carboxyl-functionalized CNT solutions (0.01% and 1% by weight) prior to slow pyrolysis. Untreated hickory and bagasse biochars (HC and BC, respectively) and CNT–biochar composites (HC–CNT and BC–CNT, respectively) were characterized, and the methylene blue (MB) sorption ability of the resulting chars was evaluated in batch sorption experiments. The addition of CNTs significantly enhanced the physiochemical properties of the biochars with HC–CNT-1% and BC–CNT-1% exhibiting the greatest thermal stabilities, surface areas (351 and 390m2g−1, respectively), and pore volumes (0.14 and 0.22ccg−1, respectively). Sorption kinetic and isotherm data showed that, among the biochars examined, BC–CNT-1% had the highest MB sorption capacity (6.2mgg−1). While increased pH (up to ∼7), promoted the uptake of MB by all the biochars, whether coated or not, increasing ionic strength decreased the uptake of MB by all biochars tested. These findings suggest that electrostatic attraction was the dominant mechanisms for the sorption of MB onto the chars, though diffusion controlled its rate. Hybridized CNT–biochar nanocomposite can thus be considered a promising, inexpensive sorbent material for removing dyes and organic pollutants from aqueous systems.

The Effect of Ultrasonic Treatment and Gamma Radiation on the Thermal Conductivity of TPNR Hybrid Nanocomposites

This paper discusses the effect of Gamma radiation and ultrasonic treatment time on hybrid nanofillers nanoclay and multi-walled carbon nanotubes (MWCNTs) as reinforcing agents to improve the thermal conductivity of TPNR. The laser flash technique was also employed to determine the thermal conductivity of the hybrid nanocomposite. The thermal conductivity of hybrid nanocomposites that were sintered at 30 to 150 °C did not show a monotonous change with MWCNTs as the filler has a high thermal conductivity compared to nanoclay by using different dose of gamma radiation or with different time of ultrasonic treatment. TEM results showed a combination of intercalated-exfoliated structure of OMMT and the dispersion of MWCNTs in the TPNR composite. The probability that hybrid nanoparticles form a network depends on the interaction between the particles, on their shape (aspect ration), preparation conditions and on their inter-particle distance will control the thermal conductivity of the hybrid nanocomposite.

Thermal Conductivity, Thermal Diffusivity and Specific Heat of TPNR Hybrid Nanocomposites at Different Temperatures

This paper discusses the inclusion of hybrid nanofillers nanoclay and multi-walled carbon nanotubes (MWNTs) as reinforcing agents to improve the thermal properties of TPNR. The laser flash technique was also employed to determine the thermal conductivity, thermal diffusivity and specific heat capacity of the nanocomposite. Two types of hybrid nanofillers were introduced into TPNR, which are untreated hybrid composites (UTH) prepared from MWNTs (without acid treatment)-nanoclay and treated hybrid composites (TH), consisting of acid treated MWNTs and nanoclay. The thermal properties of treated hybrid composites are better than untreated hybrid composites. The thermal conductivity of untreated hybrid composites that were sintered at 30 to 150 oC did not show a monotonous change with MWNTs as the filler has a high thermal conductivity compared to nanoclay. The results showed that the thermal diffusivity decreased with the increasing of temperature. The specific heat of all the measured samples increases linearly with the measured temperature from 30°C to 150°C.

Carbon nanotube based aliphatic hydrocarbon sensor

A hybrid multi-walled carbon nanotube (MWCNT) based chemical sensor was designed and developed by integration of microfabrication techniques with nano-assembly. This integrated sensing mechanism on a chip, comprised of thiol functionalized MWCNTs that functioned as transducers which were integrated with micro-electrode array measurement sites. The detection of the four fundamental hydrocarbons belonging to the aliphatic hydrocarbon family--methanol, ethanol, propanol and butanol was experimentally demonstrated. High degree of selectivity was demonstrated by repeated robust identification of individual hydro carbons belonging to the same family. The sensor demonstrated 1 ppm detection sensitivity. The detection mechanism was based on nano-scale transduction of the detection of the localized binding event between the functional binding sites and the chemical species of interest. Specific electrical signatures for each of these chemicals were identified using multiple levels of data analysis comprising of Fast Fourier Transformation (FFT) and Power Spectral Density (PSD). The sensor demonstrated a rapid response time with portability, accuracy and versatility for the in situ detection of multiple chemical agents, with potential for automation.