CNT Nanocomposites Research Articles

Oxides overlayer confined Ni3Sn2 alloy enable enhanced lithium storage performance

Sn-based materials have been expected as promising anodes in lithium-ion batteries (LIBs) owing to the high theoretical specific capacity (over 2 times of graphite), low price and environmentally friendliness. However, the development of Sn-based materials is always restricted by the poor cyclic and rate performance caused by low conductivity. To address these problems, NiO&SnO2 (NiSnOx) surface oxides overlayer confined Ni3Sn2 particles supported on carbon nanotubes (Ni3Sn2@NiSnOx/CNT) are fabricated via a simple impregnation-reduction-oxidation method. Noteworthy, such hierarchical composites feature several merits including: (i) the oxides overlayer in-situ generates a nanometric matrix of Li2O, which separates the electrolyte from the active anodes, and accelerate lithium extraction from the anode material; (ii) the Ni matrix provides sufficient space to adjust the volume change during lithiation/delithiation processes; (iii) the CNT provides interconnected electronic conductive networks. As LIBs anodes, Ni3Sn2@NiSnOx/CNT exhibits higher specific capacitance values (1521 mA h g−1), superior rate capability (46% capacity remain at 50 times current amplification) and better cyclic stability (1041 mA h g−1 after 1000 cycles). Relying on the excellent electrochemical performance, the hierarchical Ni3Sn2@NiSnOx/CNT nanocomposites are considered as a promising anode material for LIBs.

CNT-based electro-responsive shape memory functionalized 3D printed nanocomposites for liquid sensors

3D printing of conductive polymer nanocomposites, which combines the electrical conductivity of nanofillers with customer-designed geometries, is promising for various sensors. However, the single shape of sensors restricts their environmental adaptability if the detecting environment changes. Herein, 3D and 4D printing of poly (D,L-lactide-co-trimethylene carbonate) (PLMC)/CNT nanocomposites with electro-responsive shape-changing capability was achieved by direct ink writing (DIW). The rheological and solvent evaporation capabilities of PLMC/CNT ink were modulated to make it printable. Electrical, mechanical, thermal and shape memory properties were investigated and various structures from micro to macro were constructed. The printed structure showed excellent shape-changing behavior under 25 V within 16 s. Then UV photoinitiators were introduced to trigger hydrogen abstraction reaction to make PLMC chains form cross-linking networks. The modified composite ink was printed into shape-changing liquid sensors. The influence of three solvents and layer thickness on liquid sensitivity was compared. The shape-changing capability helped the sensor maintain a high precision for liquid detection. The sensor in its original, deformed and recovered shape showed similar changing trend of resistance and exhibited excellent repeatability. We envision wide environmental adaptability of using the shape-changing sensor for detecting leakage of various solvents in varying environment.

Enhanced thermoelectric figure of merit in Bi2Te3–CNT–PEDOT nanocomposite by introducing conducting interfaces in Bi2Te3 nanostructures

Bi2Te3–CNT–PEDOT nanocomposites have been synthesized by mixing PEDOT:PSS with hydrothermally synthesized Bi2Te3–CNT nanocomposites. Introducing conducting interfaces by adding PEDOT in Bi2Te3–CNT boosts the charge carrier mobility, resulting in improved electrical conductivity and simultaneously lowering the lattice thermal conductivity by enhancing phonon scattering and thus resulting in two-fold enhancement of the figure of merit. The detailed mechanism behind the enhancement of charge carrier mobility is discussed by considering the role of conducting interfaces and strong coupling of CNTs and PEDOT conducting chains. The formation of a large number of interfaces in Bi2Te3–CNT–PEDOT nanocomposites acts as strong scattering centers and thermal barriers for long-wavelength phonons, which reduces the lattice thermal conductivity. The formation of interfaces between Bi2Te3 nanostructures and CNT–PEDOT conducting channels has been studied by Kelvin probe force microscopy which clearly showed a smaller interface potential barrier for the Bi2Te3–CNT–PEDOT nanocomposite.

Effect of temperature on elastic properties of CNT reinforced nanocomposites

The paper presents a hybrid approach utilizing molecular dynamics simulation and finite element modeling to determine the elastic properties of CNT reinforced nanocomposites. The CNT, epoxy and interface between the CNT and epoxy are analyzed for variation in temperatures and their properties are determined using the Molecular Dynamic simulation. The results obtained from the MD simulation are used as an input in the FE modeling of the long and the short CNT nanocomposites. The elastic properties are analyzed for possible parametric variations of the volume fraction of CNTs, and for the variation of interfacial thickness between CNT and epoxy at different values of temperatures. The significant effect of interface thickness is found on the effective Young’s modulus of the CNT reinforced composite at the high values of temperature. The equations for calculating the effective Young’s modulus are proposed for different temperature zones, which may be used to estimate the temperature behavior of the CNT/epoxy composites with suitable accuracy.

Thermal Behavior of Spark Plasma Sintered Alumina-Based Nanocomposites

$$\hbox {Al}_{2}\hbox {O}_{3}$$ /SiC and $$\hbox {Al}_{2}\hbox {O}_{3}$$ –CNT nanocomposites have been fabricated by spark plasma sintering (SPS). Thermal properties (e.g., thermal diffusivity, specific heat capacity, and thermal conductivity) of the nanocomposites have been investigated at room temperature and at elevated temperatures for different nanophase contents and SPS temperatures. The field emission scanning electron microscopy with energy-dispersive spectroscopy, and transmission electron microscopy has been used to investigate the microstructure of nanocomposites. The thermal properties of the nanocomposites as well as those of pure alumina were investigated using direct measurement methods. The results showed that a maximum thermal conductivity of 34 W/m K was achieved on alumina after SPS at $$1400\,^{\circ }\hbox {C}$$ , while alumina containing 5 wt% SiC and 1 wt% MWCNTs nanocomposites have maximum thermal conductivities of 24.15 W/m K and 29.62 W/m K, respectively, at a SPS temperature of $$1500\,^{\circ }\hbox {C}$$ . The thermal properties of alumina decrease with the addition of the SiC and MWCNT nanophases, increasing its suitability for electro-discharge machining and fabrication of affordable products with intricate parts. The thermal behaviors of pure alumina and of the nanocomposites at elevated temperatures showed a decrease in the thermal diffusivity and thermal conductivity of alumina–SiC nanocomposites with increasing measurement temperature, while the specific heat capacity increased with increasing measuring temperature. The measurement properties correlated with the microstructure, and various transport phenomena were clearly explained.

Recent Advances in the Processing and Properties of Alumina⁻CNT/SiC Nanocomposites.

An alumina-based nanocomposite is fabricated through the addition of secondary nanophase material to an alumina matrix to alter and tailor the properties of alumina. The addition to alumina of semi-conductive materials, such as silicon carbide (SiC), and high conductive materials, such as carbon nanotubes with a characteristic size in the nanometer range, can alter the mechanical strength, hardness, toughness, and electrical and thermal properties of alumina. This paper discusses recent advances in the synthesis of alumina–SiC and alumina-carbon nanotube (CNT) nanopowders and their consolidation using conventional and non-conventional techniques. Mechanical (hardness, fracture toughness and flexural strength) and functional (thermal and electrical) properties are discussed. The influence of the microstructure on the properties of alumina–SiC and alumina–CNT nanocomposites is discussed. Furthermore, potential applications and current related research trends are described.

Graphene/pyrrolic-structured nitrogen-doped CNT nanocomposite supports for Pd-catalysed Heck coupling and chemoselective hydrogenation of nitroarenes

This work focused on the synthesis of 3D Pd-based nanocomposites which were tested in Heck coupling reactions and for the hydrogenation of nitroarenes. This was achieved by fabrication of graphene oxide/nitrogen-doped carbon nanotubes (G/N-CNTs) by mechanical grinding of 2D graphene oxide (GO) and 1D oxygen-treated nitrogen-doped CNTs (N-CNTs-OT) in a 3:1 ratio, respectively. The fabrication of G/N-CNTs is to overcome the habitual aggregation and restacking of graphene sheets. Palladium nanoparticles (Pd NPs) were deposited on the 3D G/N-CNTs nanocomposites via metal organic chemical vapour deposition method. The 3D Pd-based nanocomposites were characterized by TEM, SEM, HRTEM, XRD, TGA, XPS, ICP-OES, elemental analysis, BET analysis and Raman spectroscopy. For the Heck coupling reactions, aryl halides, olefins and 3D Pd-based nanocomposites were mixed in a suitable solvent and the reaction carried under microwave irradiation. The chemoselective hydrogenation of nitroarenes was done with dry ethanol in a Paar reactor, purged with H2 gas. These catalysts demonstrate excellent activity and selectivity in both reactions. The remarkable activity of the 3D Pd-based nanocomposites in Heck reactions and hydrogenation of nitroarenes may be attributed to the small particle size (3–10 nm) and a high degree of dispersion of Pd NPs. A comparative experiment was conducted with Pd/AC, Pd/CNTs, Pd/G/CNTs and Pd/rGO. Pd/G/N-CNTs-OT showed higher activity and selectivity than Pd/G/CNTs, Pd/G/N-CNTs, Pd/rGO and Pd/N-CNTs counterpart.

Efficient catalytic removal of airborne ozone under ambient conditions over manganese oxides immobilized on carbon nanotubes

MnOx–CNT nanocomposites are efficient towards ozone decomposition owing to the electron transfer from the CNTs to MnOx that facilitates the activation of ozone.

The effect of electro-polymerization method on supercapacitive properties of poly (o-Anisidine)/CNT nanocomposites

The aim of this work refers to study the effect of electro-polymerization method on supercapacitive properties of a known polymer nanocomposite. Herein, poly (o-Anisidine)/multi-walled carbon nanotube (POA/CNT) nanocomposites for supercapacitor applications are prepared by various electrochemical techniques including potentiodynamic, potentiostatic and galvanostatic. The electrochemical response of the prepared POA/CNT by potentiostatic method, is higher than those which are prepared by other methods. The scanning electron microscopy images show that as the preparation method changes from galvanostatic to potentiostatic, the nanocomposite possesses more pronounced porosity. Also, electrochemical impedance spectroscopy shows that with changing the electro-polymerization method from galvanostatic to potentiostatic, the charge transfer resistance decreases. The obtained specific capacitances by galvanostatic charge-discharge measurements for the nanocomposites which are prepared by potentiodynamic, potentiostatic and galvanostatic methods at 0.6 A g−1 are evaluated at about 177, 323 and 81 F g−1, respectively. Moreover, energy densities for the composite which are prepared by potentiostatic, potentiodynamic and galvanostatic methods at 0.6 A g−1, are calculated at about 16, 8.8 and 4 Wh kg−1, respectively. The results indicate that the electrode material prepared by the potentiostatic method, exhibits a better supercapacitive performance.

Simplification and development of McLachlan model for electrical conductivity of polymer carbon nanotubes nanocomposites assuming the networking of interphase regions

This paper simplifies and develops the conventional model suggested by McLachlan for electrical conductivity of polymer CNT nanocomposites. The original model expresses the conductivity as a function of filler concentration, filler conductivity, filler percolation threshold and an exponent. However, this model is developed by considering the roles of interfacial tension between polymer matrix and nanoparticles, tunneling distance between adjacent nanotubes, interphase regions around nanoparticles and waviness of CNT. The experimental results of conductivity for some samples and the analysis of the effects of various parameters on the conductivity evaluate the developed model. The predictions demonstrate fine agreement with the experimental results and the parameters show acceptable roles in the conductivity of nanocomposites. A large tunneling distance significantly decreases the conductivity to zero. Likewise, the higher and slighter surface energies of the polymer matrix and filler, respectively cause an improved conductivity. A thin interphase produces very low conductivity, while a thick interphase and a low waviness improve the conductivity.

Effects of multi-walled carbon nanotubes (MWCNTs) on the degradation behavior of plasticized PLA nanocomposites

Polymer blend nanocomposites based on polylactic acid (PLA) were prepared via simple melt blending and investigated for its biodegradation behavior. The CNTs were surface-modified using acid treatment, and characterizations of composites were done using FTIR. FTIR spectra confirmed the surface modification of CNTs. The water uptake and weight loss behavior in hydrolytic analysis of CNT and m-CNT nanocomposites at different temperatures (25 and 45 °C) were studied. It was found that the water absorption and weight loss of nanocomposites increase by incorporation of CNTs and m-CNTs up to 2% for all samples, with and without PEG loading. In sample PLA/CNTs, 2% CNTs loading shows 1.18% water uptake at 25 °C and increases to 1.95% at 45 °C water immersion, whereas, in PLA/m-CNT nanocomposites, the water uptake reduces at 1.16% at 25 °C and 1.50% at 45 °C of analysis. In the meanwhile, the weight loss of 2% CNTs loading in PLA shows 2.88% at 25 °C and 6.28% at 45 °C, and for m-CNTs loading, the weight loss exhibits 2.09% at 25 °C and 5.29% at 45 °C. This proved the modified CNTs be able to retard the ability of nanocomposites degradation. The effect of plasticizer addition in nanocomposites was studied by loading 5 and 10% PEG. As expected, the inclusion of PEG enhanced the rate of degradation in both hydrolytic and soil burial studies. For the same amount of 2% CNTs inclusions and 10% PEG, at 45 C, the water uptake shows 5.56% as compared with 5% PEG loading, only 3.1% water uptake is shown. In soil burial test, the weight loss also increases with the addition of nanofiller. PLA/m-CNTs show lower weight loss which is only 4.50% and around 7.02% for PLA/CNTs nanocomposite. In the other hand, 10% PEG loading shows an increase in the weight loss in both CNT and m-CNT nanocomposites. Results from this study demonstrate that the inclusion of CNTs and m-CNTs into polymer matrix could increase the environmental persistence of polymers in lakes, landfills and surface waters.

Dye diazonium-modified multiwalled carbon nanotubes: Light harvesters for elastomeric optothermal actuators

Novel elastomer/modified carbon nanotube nanocomposites were prepared by melt mixing ethylene vinyl acetate (EVA) matrix with dye-grafted multiwalled carbon nanotubes (MWCNTs, CNTs in short). The latter were prepared by spontaneous reactions of diazotized Azure A (AA-N2+), Neutral Red (NR-N2+) and Congo Red (CR-N2+) dyes with CNTs in water at RT. The dispersion of the dye-modified CNTs was facilitated with cholesteryl 1-pyrenecarboxylate (PyChol) surfactant. The EVA/modified CNT nanocomposites were employed as optothermal actuators. The photo-actuation measurements were performed on the un-stretched as well as the stretched strips of pristine EVA and EVA/CNT-dye nanocomposites using a dynamic mechanical analyzer (DMA) equipped with a red light emitting diode (red LED) at a wavelength of 627 nm illuminated either 10 s or 30 s. The concentration of modified dyes, the use of PyChol surfactant and the applied pre-strain were the parameters investigated in this work.To sum up, the nanocomposites prepared so far could be regarded as promising optothermal actuators used for touch displays visually impaired people.

Novel porous FexCyNz/N-doped CNT nanocomposites with excellent bifunctions for catalyzing oxygen reduction reaction and absorbing electromagnetic wave

In this work, a novel porous iron-based nanocomposite containing Fe3C, Fe3N, Fe (FexCyNz) and nitrogen doped carbon nanotubes (N-CNT) was designed and prepared. The typical product (FexCyNz/N-CNT-1000) possesses a unique characteristic of mesoporous structure with high BET surface area (401.5 m2 g−1) and outstanding electrocatalytic performance for oxygen reduction reaction (ORR) in alkaline solution, such as high limiting currents, superior methanol tolerance, relatively high stability and a near four-electron ORR pathway. More importantly, the onset potential of the representative sample is pretty close to that of commercial Pt/C. Surprisingly, the FexCyNz/N-CNT-1000 exhibits excellent electromagnetic (EM) wave absorption property, especially in the frequency range of C-band. The composite filled with 12% of FexCyNz/N-CNT-1000 sample in paraffin displays a maximum reflection loss (RL) of −25.1 dB at 4.5 GHz with a thickness of 4.0 mm, meanwhile, the absorption bandwidths below -10 dB (90% absorption) were 8.2 GHz with the variation thickness ranging from 2.0 to 5.0 mm. Consequently, we believe the present study provides a good reference for synthesizing novel multifunctional nanomaterials.

Probabilistic multiscale modeling of 3D randomly oriented and aligned wavy CNT nanocomposites and RVE size determination

This paper presents a probabilistic multiscale approach to model the random spatial distribution of local elastic properties arising from the heterogeneous waviness and orientation of CNT fillers within a 3D microscale continuum representative volume element (RVE) of a CNT-reinforced polymer matrix. The proposed direction-sensitive 3D Karhunen-Loève expansion (KLE) provides the basis to simulate stochastic variations in the CNT orientations rather than assuming a perfect alignment. Computational homogenization analyses are carried out to investigate the effects of the statistical parameters of random CNT waviness on the microscale continuum RVE size. The proposed probabilistic multiscale modelling framework allows to consider the uncertainty associated with the use of CNT nanocomposites for various applications.

Functionalization and Melt-compounding of MWCNTs in PA-6 for Tribological Applications

The present study focuses on the fabrication and mechanical property evaluation of PA-6/MWCNT nanocomposites reinforced with microwave-functionalized MWCNTs. The MWCNTs were subjected to microwave radiation in the solution of H2SO4 and HNO3 for 3 minutes, with the aim of achieving better and faster functionalization. The change observed in the crystal structure of PA-6 matrix after CNT addition suggested improved nucleation due to well-dispersed MWCNTs after functionalization. The tensile strength of PA-6 increased by approx. 12 % and 15 % after addition of pristine and functionalized MWCNTs, respectively. This was credited to improved interaction between CNTs and PA-6 matrix. The dispersion quality of CNTs in PA-6 matrix was verified by FEG-SEM, while the fractography of composites revealed polymer sheathing of PA-6 matrix around CNTs. This again contributed in improving the elongation of the composites by approx. 10 %. The wear resistance of the composites also improved appreciably, irrespective of the applied load. The specific wear rate of PA-6/CNT nanocomposite reinforced with functionalized MWCNTs increased by approx. 60 to 70 %, while coefficient of friction reduced by approx. 30 to 40%.

An efficient electrochemical performance of Fe2O3/CNT nanocomposite coated dried Lagenaria siceraria shell electrode for electrochemical capacitor

α-Fe2O3/CNT nanocomposite was successfully synthesised via in-situ co-precipitation method. The structural properties were studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The nanocomposite was uniformly coated on dried shell of Lagenaria siceraria (LS) and directly used as the working electrode for electrochemical investigation. It was found that the as-prepared Fe2O3/CNT-LS electrode exhibited high capacity, better cycling stability and rate capability. This improved performance was attributed to the spongy, fibrous and networking structure of Lagenaria siceraria dried shell, which allowed fast diffusion of electrolyte ions and structural stability. This Fe2O3/CNT-LS electrode can be promising candidate for energy storage applications.

Synthesis and Analysis of Aluminium 6063, Graphite and CNT (Hybrid) Nano Composites by using Powder Metallurgy

Synthesis and Analysis of Aluminium 6063, Graphite and CNT (Hybrid) Nano Composites by using Powder Metallurgy

Easy Synthesis of Ordered Mesoporous Carbon–Carbon Nanotube Nanocomposite as a Promising Support for CO2 Photoreduction

An easy solid–liquid grinding hard-templating route was demonstrated for the preparation of an ordered mesoporous carbon–carbon nanotube (OMC–CNT) nanocomposite by using natural soybean oil as a carbon source, which is a kind of reproducible liquid seed fat derived from soybean. The as-prepared OMC–CNT nanocomposite has bimodal mesostructures with a relative large pore volume and high surface area which can potentially be used as support in real catalysis/photocatalysis. Indeed, we have demonstrated that such an OMC–CNT nanocomposite used as a support for g-C3N4 catalyst exhibited an excellent photocatalytic performance in the reduction of CO2 with H2O. The excellent photocatalytic activity of the g-C3N4/OMC–CNT catalyst can be ascribed to its unique structure of carbon support with numerous favorable properties such as interconnected and hierarchical mesostructure, large surface area, and high electronic conductivity, which contributes to the diffusion and mass transfer of reactants or products; meanwhil...

Synthesis and characterization of novel nanocomposite by using kaolinite and carbon nanotubes

Abstract Environmental Pollution has increased tremendously since last few years as a result of urbanization leading to environmental, geological and global changes. There are numerous emerging pollutants which are toxic in nature. Since they may have critical environmental repercussions they have to be deactivated or mitigated by various technical means. Therefore, there is a need to develop new and novel smart material for sustainable environmental pollution control. Various types of clay and carbon materials are well known for their application in environmental protection using their properties of adsorption. However, they have been used separately. Keeping this thought, new material using kaolinite (kaol) and multiwalled carbon nanotubes (MWCNT) has been developed with the potential application in water treatment. Kaol has been modified by chemical treatment method to get NH2 bondings as is evident from Fourier transform infrared (FT-IR) spectroscopy showing reflection at 1618 cm− 1. MWCNT were also modified by chemical route to develop COOH bonding and it was confirmed by FT-IR reflection at 1726 cm− 1. Fabrication of nanocomposite by solution mixing method to get CONH bonding was confirmed by the reflection at 1682 cm− 1 on FT-IR spectrum. The structural properties of nanocomposites have been studied by X-ray diffraction (XRD). Mean size of crystalline structure was 32.46 nm for untreated kaol and 19.55 nm for nanocomposite. Simultaneously loss of intensity and widening of XRD reflection occurred due to change in crystalline to amorphous form. It was an indication of increase in amorphous form and reduction in crystallinity. It was evident from scanning electron microscopy (SEM), that clay- CNT nanocomposite was homogenized and has distinctive morphology. The average diameter of nanocomposite was ~ 20 nm, which was identified by high resolution transmission electron microscopy (HRTEM). Physical properties were also investigated using N2 -adsorption isotherm study; pore size distribution and Brunauer–Emmett–Teller (BET) surface area. Adsorption properties of clay and nanocomposite were calculated and their BET surface area was found to be 9.13 m2 g− 1 and 23.43 m2 g− 1, respectively. Similarly, Langmuir surface area was 13.16 m2 g− 1 and 33.95 m2 g− 1, micropore area was 6.90 m2 g− 1 and 22.11 m2 g− 1 and total pore volume was 0.04 cm3 g− 1 and 0.10 cm3 g− 1, respectively.

Microstructural and tribological properties of nanostructured Al6061-CNT produced by mechanical milling and extrusion

Wear properties of Al6061-CNT nanocomposites have been studied using dry sliding method. Nanostructured Al6061 powder has been prepared using 30 h mechanical milling of atomized powder, and mixed with different percent of CNT. The yielded mixture was subjected to mechanical milling for 0.5 and 4 h. Mixtures were cold compacted, homogenized and extruded to achieve 13 mm diameter round cross section bars. Relative density and hardness of specimens were determined for extruded samples. Maximum relative density was achieved for specimen without CNT which was about 99.848%, while maximum hardness of 236.1 HV was for specimen with 1.25 wt% CNT. Pin on disk method wear test results indicated that weight loss and wear mechanism strongly depends on normal load. At lower normal load, minimum weight loss achieved for Al6061-1.25 wt% CNT nanocomposite at abrasive and delamination mechanisms, while by increasing of normal load, minimum weight loss achieved for specimen without CNT that its wear mechanism was adhesive and delamination.