Carbon Nanotube Composite Materials Research Articles

Carbonaceous Shape-Stabilized Octadecane/Multi-Walled Carbon Nanotube Composite Materials for Enhanced Energy Storage and Electromagnetic Interference Shielding.

Developing materials for efficient energy storage and effective electromagnetic interference (EMI) shielding is crucial in modern technology. This study explores the synthesis and characterization of carbonaceous shape-stabilized octadecane/MWCNT (multi-walled carbon nanotube) composites, utilizing activated carbon, expanded graphite or ceramic carbon foam, as shape stabilizers for phase change materials (PCMs) to enhance thermal energy storage and EMI shielding, for energy-efficient and advanced applications. The integration of octadecane, a phase change material (PCM) with carbonaceous stabilizers ensures the material's stability during phase transitions, while MWCNTs contribute to improved thermal storage properties and EMI shielding capabilities. The research aims to develop novel composites with dual functionality for thermal storage and EMI shielding, emphasizing the role of carbon matrices and their MWCNT composites. SEM and CT microtomography analyses reveal variations in MWCNT incorporation across the matrices, influenced by surface properties and porosity. Leaching tests, infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) confirm the composite's stability and high latent heat storage. The presence of nanotubes enhances the thermal properties of octadecane and ΔH values almost reached their theoretical values. EMI shielding effectiveness measurements indicate that the composites show improved electric properties in the presence of MWCNTs.

An effect of Fe atom clusters doped CNTs on resistivity of PTFE dielectrics

Polymers are of interest for use on spacecraft surfaces as dielectrics and electrical insulators, and polytetrafluoroethylene (PTFE) is a polymer with mechanical advantages, but low conductivity. Fe-doped carbon nanotubes (CNT) can be added to the polymer matrix and may improve their electrical properties. This work measures the volume and surface resistivity for PTFE and PTFE + Fe-doped CNT test specimens using the Keithley 6517B Electrometer/High Resistance Meter system, by determining current levels through the samples as a function of applied voltage. The system noise current was measured and averaged to be 4.83×10−15 Amps. The results obtained show that both volume and surface resistivities of pristine PTFE increase with increasing voltage. The volume resistivity is higher if compared to the surface resistivity at the same voltage. The conductivities of PTFE + Fe doped CNTs composites are higher as compared to the pristine PTFE, which can be contributed to the Fe-doped CNTs. The conductivity of the PTFE + Fe doped CNTs composite material increases with the concentration of the Fe-doped CNTs.

Morse Code Recognition Based on a Flexible Tactile Sensor with Carbon Nanotube/Polyurethane Sponge Material by the Long Short-Term Memory Model.

Morse code recognition plays a very important role in the application of human-machine interaction. In this paper, based on the carbon nanotube (CNT) and polyurethane sponge (PUS) composite material, a flexible tactile CNT/PUS sensor with great piezoresistive characteristic is developed for detecting Morse code precisely. Thirty-six types of Morse code, including 26 letters (A-Z) and 10 numbers (0-9), are applied to the sensor. Each Morse code was repeated 60 times, and 2160 (36 × 60) groups of voltage time-sequential signals were collected to construct the dataset. Then, smoothing and normalization methods are used to preprocess and optimize the raw data. Based on that, the long short-term memory (LSTM) model with excellent feature extraction and self-adaptive ability is constructed to precisely recognize different types of Morse code detected by the sensor. The recognition accuracies of the 10-number Morse code, the 26-letter Morse code, and the whole 36-type Morse code are 99.17%, 95.37%, and 93.98%, respectively. Meanwhile, the Gated Recurrent Unit (GRU), Support Vector Machine (SVM), Multi-Layer Perceptron (MLP), and Random Forest (RF) models are built to distinguish the 36-type Morse code (letters of A-Z and numbers of 0-9) based on the same dataset and achieve the accuracies of 91.37%, 88.88%, 87.04%, and 90.97%, respectively, which are all lower than the accuracy of 93.98% based on the LSTM model. All the experimental results show that the CNT/PUS sensor can detect the Morse code's tactile feature precisely, and the LSTM model has a very efficient property in recognizing Morse code detected by the CNT/PUS sensor.

Synergistic, dual energy source production of hydrogen using Ru-promoted nitrogen-doped carbon nanotubes

In this work, ruthenium-promoted nitrogen-doped carbon nanotubes (Ru/NCN) composite materials were synthesized and utilized for the dual thermo-photo catalytic production of hydrogen using biomass-derived reactants. A spectroscopic and microscopy-based characterization showed that the composites contain rather small metallic ruthenium entities uniformly distributed and stabilized through interaction with the carbon-containing component. A highly active and (under reaction conditions) stable Ru/NCN material maximized hydrogen output under continuous operation, showing outstanding reaction rates up to ca. 30 mmol g−1 h−1 and quantum efficiencies of ca. 7.5 %. The synergy reached by the combined use of two energy sources was studied quantitatively and analyzed in the temperature range going from room temperature to 300 °C. The combination of heat and light triggers a mechanism by which the bio-molecule, methanol, is activated by light-triggered hydroxyl-type radical species and promotes the reaction up to temperatures close to 300 °C. The new composite materials based on nitrogen-doped carbon nanotubes show thus high potential to improve classic, thermal-based processes for hydrogen production.

Selective near-infrared laser programming for shape-memory polymer–carbon nanotube composite material 4D printing

Abstract Light stimulation can realise the remote control of the deformation of the specific position of 4D printing structure. Shape-memory polymer–carbon nanotube (CNT) composite materials, with outstanding near-infrared photothermal conversion rate and shape-memory ability, is one type of the most popular light responsive smart materials. However, current studies focused on the photothermal effect and shape-memory applications of light-responsive shape-memory polymer composite (SMPC) sheet structures, and there is no research on the photothermal effect in the depth direction of light-responsive SMPC three-dimensional structures. Here, we prepared a UV curable, mechanically robust, and highly deformable shape-memory polymer (IBBA) as the matrix of light responsive SMPC. CNTs were added as photothermal conversion materials. We explore the photothermal effect of near-infrared laser on the surface and depth of IBBA–CNT composites cube. Shape-memory experiments show that different folded shapes can be obtained by selective near-infrared laser programming. Selective near-infrared laser programming three-dimensional movable type plate shows a programming application in depth direction of three-dimensional light-responsive intelligent structure. This research extends the application of near-infrared laser in 4D printing to the depth direction of intelligent structures, which will bring more complex and interesting 4D printing structures in the future.

Enhanced thermoelectric and mechanical performance of fully conjugated block polythiophene modified with polar ethylene glycol side chains/single-walled carbon nanotube composite materials

Composite materials comprised of conductive polymers and single-walled carbon nanotubes (SWCNTs) display enhanced thermoelectric and mechanical performance.

Preparation and electrical properties analysis of waterborne epoxy resin carbon nanotube composite materials

Preparation and electrical properties analysis of waterborne epoxy resin carbon nanotube composite materials

Preparation and electrical properties analysis of waterborne epoxy resin carbon nanotube composite materials

Preparation and electrical properties analysis of waterborne epoxy resin carbon nanotube composite materials

Additive Manufacturing of Ti-6Al-4V with Carbon Nanotube Composite Material

Abstract This research is dedicated to investigating whether mechanical properties of Ti-6Al-4V (Titanium Grade 5) base material for additive manufacturing processes can be improved by addition of carbon nanotubes in the base material. Based on other research results with other materials, the assumption was made that reinforcing Ti-6Al-4V material with carbon nano-tubes should improve mechanical properties of the base material by 15–20 % in the additive manufacturing process. The research was divided in two steps, the first one was to investigate pure Ti-6Al-4V material and find optimal additive manufacturing processing parameters, which could maintain necessary quality standards and achieve material density levels higher than 98 % and tensile strength higher than 1000 MPa. The second part was to mix base powder with carbon nanotubes and using previously obtained processing parameters print test samples to investigate how a carbon nanotube concentration in a base powder would influence mechanical properties of the base material.

Tailoring fractal structure via 3D printing to achieve flexible stretchable electrodes based on Ecoflex/CNT/CF

Flexible electrodes are crucial for the widespread application of flexible electronics. Flexible stretchable electrodes are a research hotspot for finding a solution for the inability of flexible electrodes to withstand large deformations. In this study, the suitability of silicone rubber (Ecoflex), carbon nanotube (CNT), and carbon fiber (CF) composite materials for flexible devices and their ratios were evaluated for the first time. 3D-printed electrodes based on fractal structures with tensile insensitivity and high linearity were prepared to achieve integrated stretching of flexible devices. To demonstrate the benefits and impact of fractal structures on electrode performance, we fabricated flexible stretchable electrodes with four distinct designs: horseshoe, U-shaped, rectangular, and triangular. The tensile properties of these structures were theoretically calculated and validated through simulations and experiments; the horseshoe design proved to be the softest. Furthermore, we evaluated the performance of the prepared third-order flexible stretchable electrodes for gas-detection applications and achieved promising results, demonstrating the significant potential of these electrodes for wearable gas detection.

Application of carbon nanotube composite materials in aviation

Carbon nanotube has unique structure, excellent performance, unique one-dimensional hollow structure, and extremely low density. These advantages determine that carbon nanotube has mechanical properties, electrical properties, and adsorption properties that other materials cannot match. Carbon nanotube, as one of the popular research projects of scientists in the world today, has very broad and attractive application prospects in the fields of semiconductor devices, hydrogen storage, sensors, adsorption materials, battery electrodes, catalyst carriers, etc. The field of science and technology also shows great application prospects. Combined with the urgent needs of aircraft in light and high-strength structures, lightweight cables and efficient thermal control, the carbon nanotube is considered to be the booster of the next generation of aerospace and is expected to become an important pillar in the future of aviation. This paper comprehensively analyzes the application of carbon nanotubes in aircraft wheels, aircraft engine blades, aircraft avionics systems and electromechanical system displays and looks forward to its application prospects and feasibility in the aviation field. Developments in aviation present challenges and opportunities.

Electrochemical sensor using cobalt oxide-modified porous carbon for uric acid determination.

An electrochemical sensor for the detection of uric acid was constructed using cobalt oxide-modified porous carbon@multi-walled carbon nanotube (MWCNTs) composite material for the modification of theelectrode. Firstly, ZIF-67 is generated on carbon nanotubes using thesurfactant cetylammonium bromide (CTAB) as template. The vesicles generated by CTAB act as nucleation sites for the in situ growth of ZIF-67. Then, cobalt oxide-modified porous carbon was obtained after high-temperature carbonization of ZIF-67, leading to the formation of cobalt oxide-modified porous carbon@MWCNT composite materials. Co-N and Co-O active sites on the composite material can improve the oxidation of uric acid on the electrode surface, leading to enhanced sensitivity and selectivity for uric acid detection. The sensor has a good linear range from 1 to 40 μM for uric acid detection with a detection limit of 0.09 μM. The sensor was utilized for determination of uric acid in actual serum samples.

Construction and electrochemical properties of carbon nanotube composite Mn-MOFs materials electrode for high-performance flexible supercapacitors

Metal organic frameworks (MOFs) as electrode materials for supercapacitors have attracted extensive attention due to their porous structure. However, the poor conductivity of MOFs limits the charge transfer. In this work, Mn-MOF/carbon nanotube (CNT) composites were grown directly on carbon cloth (CC) in one step by the traditional hydrothermal synthesis of MOFs to improve the electrical conductivity of Mn-MOFs. The structural and performance tests show that CNTs, as a conductive backbone, can connect Mn-MOFs to each other, which can obviously solve the problem of poor conductivity of MOF materials. The Mn-MOFs/CNTs/CC electrodes show a larger specific capacitance and excellent cycling stability by electrochemical tests. Compared to the original Mn-MOF electrode, the surface capacitance obtained increases from 188.8 mF·cm−2 to 385.8 mF·cm−2 at a current density of 0.8 mA·cm−2 and maintains a high capacitance retention of 118% after 5000 charge/discharge cycles at a current density of 5 mA·cm−2. This work confirms that the in- situ synthesis of MOFs and CNTs has promising applications in fabric-based flexible supercapacitors.

Dielectric Properties of Epoxy Composites Containing Silver Nanoparticle and Carbon Nanotube over the X-Band Frequency

Materials with high dielectric properties have become interested due to their important applications, mainly in electronics and energy storage. This study assesses the dielectric properties of epoxy composites containing silver nanoparticles (AgNPs) and carbon nanotube (CNT) composite materials. These samples' permittivity and reflective properties were measured using Vector Network Analyser (VNA) within the X-band frequency (8.2 – 12.4 GHz). Samples were prepared at various loading (0.1-5 wt.%), with various thickness of (0.5, 1.0, 1.5 and 2.0 mm). Regardless of the fillers loading and sample thickness, it was found that the values of real permittivity, er', remain constant along the frequency range. At the same sample thickness, it was found that the values of both er' and er'' increase as loading increases, indicating the function of AgNPs and CNT in enhancing the dielectric and electrical conductivity properties of epoxy composites, respectively. The highest value of er' is recorded as 5 F/m (at f = 8.2 GHz), measured at 5 wt.% loadings and 0.5 mm sample thickness. Measurement on S11 parameters at f = 8.2 GHz indicated that the SER values are between 9 dB and 15 dB, with no obvious pattern observed, regardless of the fillers loading and sample thickness. This study highlights the dielectric properties improvement of epoxy composites by incorporating dual fillers.

Effect of dispersibility of carbon nanotubes on the hardness and thermal properties of polyphenylene sulphide/carbon nanotube composites obtained using solution mixing and melt blending methods

Polyphenylene sulphide (PPS)/carbon nanotube (CNT) composite materials (combining PPS and multi-walled CNTs modified with carboxyl groups) were blended using two methods: (1) solution mixing with 1-chloronaphthalene and (2) melt blending. The dispersion states of CNTs in PPS prepared by the two methods were evaluated using Raman spectroscopic mapping. The effect of the dispersibility of CNTs on the physical properties of the composite materials was evaluated by measuring their thermal behaviour and Vickers hardness. Raman spectroscopic mapping revealed that the dispersion states of CNTs in composites obtained via the solution mixing method were more uniform than in those obtained via melt blending methods. This improved uniformity in the dispersion states of CNTs in the solution mixing method can be attributed to the prior dispersion of CNTs in the solution. Additionally, thermal properties such as the crystallisation and glass transition temperatures, and mechanical properties such as the Vickers hardness of the solution-mixed composite material were higher than those of the melt-blended composite. These results indicate that the uniform dispersion of CNTs increases the contact area between PPS and CNTs, which causes an increase in the crystallisation temperature and a further hardness effect.

Facet effect of MnCo2O4 nanocrystals for enhanced oxygen reduction reaction in alkaline medium

Understanding the mechanism of the four-electron transfer oxygen reduction reaction (ORR) and the structure–activity relationship of spinel oxide remains a challenge. Two bimetallic manganese-cobalt spinel oxide supported on carbon nanotube (MnCo2O4/CNT) composite materials with different crystal planes exposed are synthesized in this paper by adding unequal amounts of ammonia during the hydrothermal process. Physical characterization results indicate that the exposed surfaces of the two materials (MnCo2O4/CNT-100, MnCo2O4/CNT-800) are (001) and (112), respectively. Electrochemical tests demonstrate that the MnCo2O4/CNT-800 composite material exposed to the (112) crystal plane exhibit higher ORR catalytic activity in alkaline electrolyte, with a half-wave potential of 0.79 V and a limiting current density of 5.15 mA cm−2. The outstanding activity is attributed to the greater specific surface area, the exposure of high-index crystal plane and the high-valence metal sites on the surface. Density functional theory (DFT) calculations reveal that the active sites on the (112) crystal plane have improved adsorption and ORR thermodynamics. This work provides a strategy for developing the advanced bimetallic spinel electrocatalysts by adjusting the exposed plane.

Determination of trace perfluorinated compounds in environmental water samples by dispersive solid- phase extraction-high performance liquid chromatography-tandem mass spectrometry using carbon nanotube composite materials

In this work, carbon nanotubes (CNTs) on silica rod (SiO2) composite materials were prepared to extract six perfluorinated compounds (PFCs) in real environmental water samples by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The as-synthesized sorbents, hereafter referred to as CNT@SiO2, were employed for dispersive solid-phase extraction (d-SPE). Perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctane sulfonate (PFOS), and perfluorodecanoic acid (PFDA) were selected as target analytes. The main extraction parameters were systematically optimized using the single-factor optimization method. The optimum adsorption parameters were as follows: adsorption time of 30 min, sorbent amount of 10 mg, pH 6 and NaCl concentration of 1.7 mol/L for sample solution, and 4 mL acetone as desorption solvent, desorption for 4 min. LC-triple quadrupole MS was conducted to quantify the selected PFCs in water samples. The mobile phase was 5 mmol/L ammonium acetate and methanol, the flow rate was set to 0.4 mL/min, the column temperature was set to 40 ℃, and the injection volume was 5.0 μL. The chromatographic separation system was equipped with a Kinetex C18 column (100 mm×2.1 mm, 1.7 μm). The mass spectrometer was operated with negative electrospray ionization in multi-reaction monitoring mode. CNT@SiO2 was prepared in five batches and used as the d-SPE sorbent, and the relative standard deviations (RSDs) of the PFC recoveries among these five batches ranged from 4.9% to 9.3%. The reusability of the CNT@SiO2 sorbent was assessed. After eight d-SPE cycles using the same sorbent, the RSDs of the PFC recoveries were 3.7%-8.2%. These results indicated that the sorbent had good stability and reusability for d-SPE. Excellent results were achieved under optimal extraction conditions. The method validation results indicated that the linear ranges were 0.4-1000 ng/L for PFNA, PFOS, and PFDA, 0.9-1000 ng/L for PFHpA, 0.7-1000 ng/L for PFHxS, and 0.6-1000 ng/L for PFOA. The correlation coefficients were 0.973-0.997. The limit of detection (LOD) and limit of quantification of the method were 0.10-0.26 ng/L and 0.33-0.87 ng/L, respectively. At 20 ng/L, the RSDs of the intra- and inter-day precisions were 2.73%-7.75% and 3.38%-8.21%, respectively. At 100 ng/L, the RSDs of the intra- and inter-day precisions were 2.95%-8.46% and 4.16%-9.14%, respectively. Finally, at 500 ng/L, the RSDs of the intra- and inter-day precisions were 2.51%-7.48% and 3.59%-9.63%, respectively. The developed method was applied to analyze six PFCs in tap water, barreled drinking water, and river water samples. PFOA and PFOS were determined in tap water at mass concentrations of 5.6 and 8.7 ng/L, respectively. No PFCs were found in barreled drinking water and river water. Satisfactory recoveries of 72.1%-109.6% at low, middle, and high spiking levels were also obtained. In conclusion, the d-SPE-LC-MS/MS method based on CNT@SiO2 composite sorbents is accurate and sensitive. The results of this study demonstrate that CNT@SiO2 is a good choice for the rapid and effective determination of PFCs from water samples. Further exploration of the use of CNT@SiO2 sorbents for the extraction and determination of trace organic pollutions in environmental samples is in progress.

Carbon Nanotubes as an Alternative to Copper Wires in Electrical Machines: A Review

The surge in electric vehicles (EVs) and their electrical appliances requires highly efficient, lightweight electrical machines with better performance. However, conventional wire used for electrical machine windings have certain limits to the current requirements. Copper is a commonly used material in electrical windings, and due to its ohmic resistance, it causes 75% of total losses in electrical machines (copper losses). The high mass of the copper results in a bulky system size, and the winding temperature of copper is always maintained at less than 150 °C to preserve the thermal insulation of the electric machine of the windings. On the other hand, carbon nanotubes and carbon nanotube materials have superior electrical conductivity properties and mechanical properties. Carbon nanotubes ensure 100 MS/m of electrical conductivity, which is higher than the copper electrical conductivity of 59.6 MS/m. In the literature, various carbon nanotubes have been studied based on electrical conductivity, temperature co-efficient with resistivity, material thickness and strength, insulation, and efficiency of the materials. Here, we review the electrical and mechanical properties of carbon nanotubes, and carbon nanotube composite materials are reviewed with copper windings for electrical wires.

Revealing the Multifunctional Electrocatalysis of Indium‐Modulated Phthalocyanine for High‐Performance Lithium‐Sulfur Batteries

The sluggish kinetics of complicated multiphase conversions and the severe shuttling effect of lithium polysulfides (LiPSs) significantly hinder the applications of Li‐S battery, which is one of the most promising candidates for the next‐generation energy storage system. Herein, a bifunctional electrocatalyst, indium phthalocyanine self‐assembled with carbon nanotubes (InPc@CNT) composite material, is proposed to promote the conversion kinetics of both reduction and oxidation processes, demonstrating a bidirectional catalytic effect on both nucleation and dissolution of Li2S species. The theoretical calculation shows that the unique electronic configuration of InPc@CNT is conducive to trapping soluble polysulfides in the reduction process, as well as the modulation of electron transfer dynamics also endows the dissolution of Li2S in the oxidation reaction, which will accelerate the effectiveness of catalytic conversion and facilitate sulfur utilization. Moreover, the InPc@CNT modified separator displays lower overpotential for polysulfide transformation, alleviating polarization of electrode during cycling. The integrated spectroscopy analysis, HRTEM, and electrochemical study reveal that the InPc@CNT acts as an efficient multifunctional catalytic center to satisfy the requirements of accelerating charging and discharging processes. Therefore, the Li–S battery with InPc@CNT‐modified separator obtains a discharge‐specific capacity of 1415 mAh g−1 at a high rate of 0.5 C. Additionally, the 2 Ah Li–S pouch cells deliver 315 Wh kg−1 and achieved 80% capacity retention after 50 cycles at 0.1 C with a high sulfur loading of 10 mg cm−2. Our study provides a practical method to introduce bifunctional electrocatalysts for boosting the electrochemical properties of Li–S batteries.

Preparation and photocatalytic degradation of Sulfamethoxazole by g-C3N4 nano composite samples

Abstract Graphite-carbon nitride (g-C3N4) was prepared by thermocondensation, and g-C3N4/BiVO4 material (GCB) and g-C3N4/CNTs composite material (GCC) were prepared by doping different contents of BiVO4 and carbon nanotubes (CNTs) with g-C3N4 samples, respectively. Then, BiVO4, CNTs, and g-C3N4 samples with different contents were doped to prepare ternary composite material (GCBC). In the performance experiment, Sulfamethoxazole (SMZ) was used as degradation material to evaluate the photocatalytic performance of the prepared samples, and the degradation reaction kinetics equation, quadric cycle stability experiment, free radical capture, and intermediates identification were studied. The intermediates of photocatalytic degradation of SMZ were analyzed by high-performance liquid chromatography-mass spectrometry. From the experimental data, it can be seen that for SMZ solution, when the reaction time T = 0 min and retention time rt = 7.53 min, there is a peak corresponding to the substance with m/z [M + H]+ of 254, which is judged as SMZ. At 20, 40, and 60 min, rt was 2.00, 7.06, and 9.57 min, indicating the presence of intermediates in the photocatalytic process. Experimental analysis shows that there are three intermediates of SMZ degradation by composite sample GCBC. In this work, three kinds of composite materials were successfully prepared, and a variety of characterization, SMZ as pollutants, test the photocatalytic performance of composite materials (GCB, GCC, and GCBC) samples, and elucidated the cyclic stability of the material, active species capture, and photocatalytic degradation mechanism.