Carbon Nanotubes Research Articles

All-in-one, flexible, diversified self-powered sensors through embedded 3D printing

Abstract Triboelectric nanogenerators (TENGs) are characterized by zero power consumption and are often employed as self-powered sensors. However, the complex manufacturing process and expensive equipment limit the further promotion and application of self-powered sensors, which have become urgent challenges in this field. Here, a simple strategy using embedded 3D printing is proposed to enable the fabrication of diverse self-powered sensors in one-step, reducing production costs while increasing design flexibility. Specifically, the designed sensors composed of the silicone as the triboelectric layer and silicone/multi-walled carbon nanotubes as flexible electrodes with excellent all-in-one structures. Meanwhile, diversified self-powered sensors with different complex structures (e.g., planar array sensors and helical icosahedron sensors) were developed to meet the diverse needs of different applications, verifying the capability of the proposed embedded 3D printing method to design and customize sensors with various shapes and structures. In addition, the applications of these functionalized self-powered sensors in cryptographic simulation, pressure position detection, and impact force recognition have been successfully demonstrated. Therefore, this self-powered sensor based on embedded 3D printing has a promising future in human-computer interaction, collision detection and other fields.

Exploring synergies between GnP and fiber orientation in enhancing mechanical, thermomechanical, and shape memory properties of carbon fiber polymer composites

Abstract This research investigates the mechanical, thermomechanical, and shape memory properties across 12 configurations of shape memory hybrid composites, varying in carbon fiber orientation: uni-directional (UD), bi-directional-Twill (BDT), and bi-directional-Plain (BDP), and multi-walled carbon nanotube weight percentages of 0.4%, 0.6%, and 0.8% elucidate the synergistic effects of fiber architecture and nanomaterial reinforcement. The fabrication process involves initially preparing GnP-modified epoxy nanocomposites through ultrasonication followed by hand layup techniques to fabricate three-phase shape memory hybrid composites. Optimal tensile performance is observed in GnP-modified UD composites at a 0.6 wt% concentration, achieving a tensile strength of 728.32 MPa and a modulus of 71.29 GPa. Furthermore, enhancements in thermomechanical and shape memory properties are noted in GnP-modified BDT composites and are further improved in GnP-modified BDP composites configurations. These improvements are attributed to enhanced interfacial bonding between the polymer and fiber, with the maximum effect observed at the 0.6 wt% BDP composite, validated by morphological analysis using FESEM. The study demonstrates that despite polymer modification, all configurations maintain high shape recovery ratios, particularly notable at 97.54% for 0.6 wt% GnP modified BDP composite, exceeding 90% across all configurations, indicating robust performance in shape memory capabilities.

Electrospun Mesoporous Ni0.5Zn0.5Fe2O4 - CNT - Hollow Carbon Ternary Composite Nanofibers as High Performance Electrodes for Advanced Symmetric Supercapacitors.

Spinel ferrites have attracted considerable interest in energy storage systems due to their unique magnetic, electrical and catalytic properties. However, they suffer from poor electronic conductivity and low specific capacity. We have addressed this limitation by synthesizing composite hollow carbon nanofibers (HCNF) embedded with nanostructured Nickel Zinc Ferrite (NZF) and Multiwalled carbon nanotubes (CNT), through coaxial electrospinning. These ternary composite nanofibers NZF-CNT-HCNF have a high specific capacity of 833 C g-1 at a current density of 1 A g-1 and have a capacity retention of 90 % after 3000 cycles. Their performance is much better than pure NZF fibers (180 C g-1) or hollow carbon nanofibers (96 C g-1), suggesting synergy between various constituents of the composite. A symmetric supercapacitor fabricated from NZF-CNT-HCNF composite nanofibers (30 % NZF) has a high specific capacity of 302 C g-1 (302 A g-1) at a current density of 1 A g-1 and has a capacity retention of 95 % after 5000 cycles. At the same current density, the device has a high energy density of 39 Whkg-1 and power density of 1000 Wkg-1 at a current density of 1 A g-1. This performance can be attributed to the high specific surface area (776 m2 g-1), mesoporosity (pore size ~4 nm), interconnectedness of the nanofibers and high electrical conductivity of CNTs. These fibers can be used as light-weight high performance electrode materials in advanced energy storage devices.

Superior Conductive, Large Diameter CNT Composite Yarn of Insulative Polymer: Inferences of a Unidirectional Compression‐Stretching Technique

ABSTRACTLarge diameter yet highly conductive Carbon Nanotube (CNT) yarn could have prospective control on high‐tech application field spanning from electronic devices to wearable textiles; although the development of such macroscopic CNTs is extremely challenging. Especially, while fabricating CNT composite yarn with polymer, insulative nature of polymeric materials inherently propagates poor electrical conductivity to CNT yarn. To address this, we have proposed an exciting approach to fabricate large dimension, highly conductive yet flexible CNT‐Thermoplastic Polyurethane (TPU) composite yarn through unidirectional compression‐stretching process. Our technique allowed TPU molecules to be well dispersed into inner and inter‐CNT bundles facilitating well flexibility while the simultaneous functions of pressure and tension allowed more closely packed CNTs network within densified CNT yarn reducing the inherent voids and contact resistance. The consequent yarn possessed high conductivity of 1613 S/cm, attractive mechanical performance (tensile strength 1.3 GPa, Young's modulus 12 GPa, toughness 100.75 MJ/m3), exceptional anti‐abrasive ability (up to 46,350 cycles) endowing its multidirectional adaptability for smart textiles. Moreover, the desirable E‐heating performance together with excellent electrical stability allows successful exploitation of the prepared CNT yarn as stretchable heater. Such amazing integrated characteristics may allow the resultant yarn to replace traditional carbon fiber in various high‐tech arena as well.

Effect of carbon nanotubes and zinc oxide on electrical and mechanical properties of polyvinyl alcohol matrix composite by electrospinning method.

In this study, polymer composite nanofibers and thin membranes were synthesized using Carbon Nanotubes (CNTs) and Zinc Oxide (ZnO) as fillers in a Polyvinyl Alcohol (PVA) matrix, aiming to evaluate their electrical and mechanical properties. The composite nanofibers and thin membranes were prepared by incorporating different weight ratios of CNTs and ZnO into the PVA matrix using electrospinning and solution casting techniques, respectively. Solutions were prepared by mixing specific weight ratios of PVA, ZnO, and CNTs, followed by magnetic stirring and ultrasonication for homogenization. Electrospinning was performed at 20kV with a syringe-to-collector distance of 14.5cm at flow rate of 2.4ml/hr. The composites were characterized using FTIR spectroscopy and Scanning Electron Microscopy (SEM). The PVA/5%ZnO/0.5%CNT composite exhibited the highest dielectric constant of 10.3 at high frequencies, while PVA/5%CNT showed the highest capacitance of 31.1 pF at 2MHz. The maximum AC conductivity of 2.72 × 10- 7S/m was also observed for the PVA/5%ZnO/0.5%CNT composite. Mechanical testing revealed significant improvements in Young's modulus, stress yield, and load yield, with PVA/5%CNT achieving a Young's modulus of 387.12 MPa and a stress yield of 6.92 MPa. The addition of ZnO and CNT fillers resulted in enhanced electrical and mechanical properties, making these composites suitable for applications in microelectronic devices and packaging materials.

A novel miniaturized potentiometric electrode based on carbon nanotubes and molecularly imprinted polymer for the determination of lidocaine.

A novel miniaturized, solid-contact potentiometric screen-printed electrode was developed for highly sensitive and selective determination of lidocaine anesthetic. The electrode integrated single-walled carbon nanotubes as a solid-contact material and a molecularly imprinted polymer as a recognition sensory material. The performance characteristics of the electrode were evaluated and optimized to display a Nernstian slope of 58.92 ± 0.98mV/decade over a linear concentration range of 4.53 × 10-7 to 6.18 × 10-3mol/l within < 6s. Thedetection limit was 7.75 × 10-8mol/l (18.16ng/ml) of lidocaine. The use of the molecularly imprinted polymer significantly enhanced the selectivity of the electrode, and carbon nanotubes increased the sensitivity, accuracy, and potential stability. The electrode was successfully used for determining lidocaine in pharmaceutical preparations and human urine. The results favorably compared with data obtained by liquid chromatography-tandem mass spectrometry.

Silk Nanofibers/Carbon Nanotube Conductive Aerogel.

Natural silk nanofibers (SNF) are attractive conductive substrates due to their high aspect ratio, outstanding mechanical strength, excellent biocompatibility, and controllable degradability. However, the inherently non-conductivity severely restricts the potential sensor application of SNF-based aerogels. In this work, the conductive nanofibrous aerogels with low-density achieved through freeze-drying by dispersing carbon nanotubes (CNT) into SNF suspension. The addition of CNT significantly increases the conductivity with improved mechanical properties of composite aerogels. SEM results reveal that the distinct hierarchical structure comprising micropores and nanofibrous networks within the pores is formed when CNT content reached 30%. Furthermore, increased cell viability suggested the excellent biocompatibility of SNF-CNT-based conductive aerogel for tissue-engineering applications. Subsequently, the elastic water-borne polyurethane (WPU) is incorporated to SNF-CNT system to construct aerogel with good sensing properties. The introduction of WPU demonstrates enhanced compressive performances and an exceptionally high elastic recovery ratio of 99.8%, thereby exhibiting a stable and lossless strain-sensing signal output at 5% strain. This study provides a feasible choice and strategy for exploring the potential application of SNF in functional aerogels.

Boron nitride nanotubes as carriers of genistein for multitherapeutic cancer treatment: A DFT study of electronic and solubility properties

Increasing cancer mortality statistics demand more accurate and efficient treatments. Nanostructures have proved to be promising choices in this regard. Nanotubes with large surface areas can play multiple roles from drug carriers in targeted drug delivery to beam absorbers in the photothermal method. While carbon nanotubes (CNTs) show cytotoxicity, Boron Nitride Nanotubes (BNNTs) offer wide bandgap and biocompatibility. In this study, we investigate the electronic and solvation properties of (5,5), (6,6), and (7,7) BNNTs computationally by the density functional theory. For multimodal therapy, we considered Iron (Fe) doping in the BNNT, which can be helpful in hyperthermia due to the magnetic moment of Fe. Our results show that doping has improved the band positions. Furthermore, we implemented an organic anticancer molecule, genistein, a metastasis inhibitor. All potent configurations connecting genistein with BNNT covalently demonstrated enhanced water solubility as compared to pristine and Fe-doped BNNTs. The results suggest that the (7,7) C3 complex is the most stable structure and the best drug carrier.

Diameter-Controlled Synthesis of Carbon Nanotubes Using [2n]Collarenes as Rigid Organic Templates.

An effective route to diameter-controlled single-walled carbon nanotubes (SWCNTs) remains elusive. The use of organic templates to precisely control the diameter of the resulting nanotubes holds great promise in this regard but has hitherto had very limited practical success. A main obstacle is the limited availability of suitable organic templates. Here, we report the diameter-controlled bottom-up synthesis of SWCNTs with elaborately designed [2n]collarenes, hydrocarbon belts consisting of alternating phenylene and 1,4-cyclohexadiene rings, as rigid organic templates. A new approach has been developed to construct these collarenes, which are then used as templates in the bottom-up growth of SWCNTs. The resulting SWCNTs exhibit narrow diameter distributions, matching the diameters of the employed collarene templates. This work greatly propels the synthesis of diameter-controlled SWCNTs.

Kinetics of Thermal Decomposition of Carbon Nanotubes Decorated with Magnetite Nanoparticles

Kinetics of Thermal Decomposition of Carbon Nanotubes Decorated with Magnetite Nanoparticles

Sulfate Oxyanion Steered d-Orbital Electronic State of Nickel-Iron Nanoalloy for Boosting Electrocatalytic Performance.

Oxyanion groups recently offer an innovative avenue for improving the sluggish kinetics of electrochemical reactions benefitting from their particular polyanion configurations and large electronegativity. Nevertheless, the exact structure design and deep regulating mechanism of oxyanion species remain poorly understood. Herein, a fresh architecture of the sulfate oxyanion coordinated nickel-iron nanoalloy on nitrogen and sulfur co-doped carbon nanotube (SO4 2--NiFe/NSCT) is newly proposed to study the activity increment effect and mechanism. The SO4 2--NiFe/NSCT displays hierarchical nanostructure with robust-wrinkled surface and highly efficient active sites. Importantly, the SO4 2- group, as a significant manipulation factor, is first evidenced to promote the oxygen reduction reaction (ORR) activity for NiFe nanoalloy under the reductive condition, showcasing outstanding bifunctional properties toward ORR and oxygen evolution reaction (OER), as well as the exceptional performance in non-aqueous Li-O2 battery. Both experimental and theoretical results elucidate that, as an electron bridge, the introduction of SO4 2- downshifts the d-band center of SO4 2--NiFe/NSCT and gives the electron transfer passageway between the H atom in OH* intermediate and the O atom in SO4 2- group, greatly optimizing the metal-intermediate interaction with weaker bond energy. This work provides a deep insight into the activity enhancement mechanism by the sulfate oxyanion.

The effect of single walled carbon nanotubes on conductivity and thermal properties of glass fiber reinforced composites

Abstract This paper reports on a comprehensive study of the effect of single-walled carbon nanotube (SWCNT) on the alternating current (AC) conductivity, thermal and morphological properties of the unsaturated polyester based glass fiber reinforced polymer composite (GFRPC). AC conductivity measurements were carried out using the impedance spectrum and thermal measurements were carried out using differential scanning calorimetry (DSC) at a temperature range of 24-900 °C and heating rates of 20 °C/min. Impedance results showed that the conductivity behavior in the nanotube-loaded composite laminate obeys a Jonscher-type mechanism. At low frequencies, the conductivity value remains almost constant for the doped material and takes the value of 10-5 S/cm. It is observed that the AC conductivity starts to increase after the critical frequency value of approximately 103 Hz and increases up to 10-2 S/cm due to hopping and tunneling mechanisms caused by space charge polarization accumulated in the local regions at high frequencies. The pure material with an insulating nature also exhibited a typical insulating behavior. Thermal testing showed that nanotube reinforcement increases thermal conductivity in three different directions. DSC thermocurves analysis also revealed that the addition of carbon nanotubes increased the glass transition temperature of the material from 180°C to 190°C. The scaling and fractal analysis methods were also applied to obtain hetero morphological structure of materials. The fractal analysis results indicated that carbon nanotube doping to the standard sample increases the coating rates, scalability and heterogeneity of the solid phase surface of the sample. The coating rates of composite surfaces were calculated as 45% and 36%, respectively. Morphology analysis revealed that the probability of finding surface particles for the nanotube-doped sample decreased compared to the undoped sample, but the fractal dimension value increased. While this value was 1.83 in the pure sample, it increased to 1.92 in the nanotube material.

Electric‐Field Catalysis on Carbon Nanotubes in Electromicrofluidic Reactors: Monoterpene Cyclizations

AbstractThe control over the movement of electrons during chemical reactions with oriented external electric fields (OEEFs) has been predicted to offer a general approach to catalysis. Recently, we suggested that many problems to realize electric‐field catalysis in practice under scalable bulk conditions could possibly be solved on multiwalled carbon nanotubes in electromicrofluidic reactors. Here, we selected monoterpene cyclizations to assess the scope of our system in organic synthesis. We report that electric‐field catalysis can function by stabilizing both anionic and cationic transition states, depending on the orientation of the applied field. Moreover, electric‐field catalysis can promote reactions which are barely accessible by general Brønsted and Lewis acids and field‐free anion‐π and cation‐π interactions, and drive chemoselectivity toward intrinsically disfavored products without the need for pyrene interfacers attached to the substrate to prolong binding to the carbon nanotubes. Finally, interfacing with chiral organocatalysts is explored and evidence against contributions from redox chemistry is provided.

Carbon Nanotubes in Cement—A New Approach for Building Composites and Its Influence on Environmental Effect of Material

An addition of carbon nanostructures to cement paste is problematic due to the difficulties in obtaining homogenous mixtures. The paper reports on a more effective way of mixing carboxylated multi-walled carbon nanotubes (MWCNT-COOH) in cement pastes. The additional biological impact of the studied nanomodified cement was analyzed in the case of two moss species’ vitality. The applied approach of obtaining a homogeneous mixture is based on intense mechanochemical mixing of MWCNT-COOH together with polycarboxylate superplasticizer (SP). As a result, a more homogenous suspension of MWCNT-COOH within a liquid superplasticizer, suitable for addition to hydrophilic cement paste, was obtained. FT-IR/Raman spectroscopy was used for materials’ characterization. To explain the mixing process at the molecular level, systematic theoretical studies using density functional theory (DFT) were performed. The structures, interaction energies and IR/Raman vibrational spectra of model carboxylic acids, mixed with functionalized SWCNTs as simplified models of real MWCNTs, were obtained. Due to the controversial opinions on the environmental hazards of carbon nanostructures, additional in vivo studies were performed. In this case, effects of cement modified by the addition of small amounts of MWCNT-COOH with SP in comparison to the composite without carbon nanostructures and control subsoil on the vitality of mosses Polytrichum formosum and Pseudoscleropodium purum were studied.

Moisture-induced mechanical property changes in natural hybrid composites with mwcnt fillers

ABSTRACT This study investigates the moisture absorption behaviour and its effects on the mechanical properties of polyester composites reinforced with jute and hemp fibres. The differences in moisture absorption between distilled water and saltwater are examined. Tensile and flexural tests are conducted on pure jute fibre-reinforced polyester composite, pure hemp fibre-reinforced polyester composite, and jute (J-P) and hemp (H-P) fibre-reinforced polyester composite. Changes in mechanical properties due to varying moisture conditions are analysed. Furthermore, the impact of a synthetic nano filler, multiwall carbon nanotubes (MWCNTs), on these composites is assessed. The study reveals that MWCNTs enhance mechanical properties, particularly in moist conditions. Fracture behaviour analysis aids in understanding the interaction between natural fibres, the matrix, and nano-reinforcement. At maximum natural fibre weight fractions (40%), moisture absorption reaches 8.17% for the J-P composite in distilled water and 9.61% in saltwater, while the H-P composite shows maximum absorptions of 6.61% and 8.27%, respectively. The hybrid composite records 4.18% and 7.17% under similar conditions. Compared to the plain jute fibre-reinforced composite, the addition of multiwall carbon tubes into the polymer matrix significantly reduces the moisture absorption capacity of the jute composite to 34.89% and 31.30% for distilled water and saltwater, respectively.

Modulation for Redox States of Single-Walled Carbon Nanotubes: Effect of Wrapping Conjugated Polymers.

Controlling the redox states of single-walled carbon nanotubes (SWNTs) is important for the optimization of their real performances in various fields. By means of in situ photoluminescence (PL) spectroelectrochemical measurements, we report a successful modulation for the redox parameters (redox potentials and electrochemical band gap) of (6,5) and (7,5)SWNTs with a simple change in conjugated polymers (CPs) non-covalently wrapped on the nanotubes. The large shift in the band gap (187 meV for (6,5)SWNTs and 101 meV for (7,5)SWNTs) was connected to the prominent difference in the interactions between the CPs and SWNTs as suggested by molecular dynamics (MD) simulations, while a striking difference in the 𝜋-electrons states of CP/SWNTs enabled the tuning of SWNTs' electronic states. Asymmetrical modulation for the reduction potential (LUMO) and oxidation potential (HOMO) of the SWNTs was observed as well. Our results can be promising for a simple but precise control of the electric states of SWNTs.

Microstructural and mechanical properties study of various lattice structures of SS316L-CNTs nano composites fabricated through additive manufacturing

Abstract In this work, various lattice structures, such as FCC (face-centered), BCC (body-centered), GD (Gyroid), and BGD (bare gyroid (without CNTs)) with four different porosities (60%, 70%, 80%, and 90%), were prepared through the SLM (selective laser melting) additive manufacturing process. Stainless Steel (SS) 316L alloy was utilized as the base material, while 0.2 wt.% functionalized CNTs (Carbon Nanotubes) were employed as reinforcement. The uniform dispersion of CNTs was analyzed using FESEM, TEM, and Raman spectroscopy. The results indicated that the plateau stress increases with the addition of CNTs, as well as with relative density, whereas energy absorption increases with the addition of CNTs. However, with increasing relative densities, energy absorption nature changes from increasing to decreasing. The results showed that among all lattice structures formed with CNTs addition, the Gyroid lattice exhibited the highest plateau stress, while the BCC lattice exhibited the lowest plateau stress.&amp;#xD;

Evaluation of Electrical Properties and Uniformity of Single Wall Carbon Nanotube Dip-Coated Conductive Fabrics Using Convolutional Neural Network-Based Image Analysis

This study proposes a convolutional neural network (CNN)-based image analysis method to evaluate the electrical properties and uniformity of conductive fabrics treated with single-walled carbon nanotube (SWCNT) dip-coating. The conductive fabric was produced by dip-coating cotton-blended spandex with SWCNT, and the surface images were scanned and preprocessed to obtain image data, while resistance measurements were conducted to obtain labels and build the dataset. SEM analysis revealed that as the number of dip-coating cycles increased, particle density and path formation improved. The CNN model learned the relationship between surface images and resistance values, achieving a high predictive performance, with an R-squared (R²) value of 0.9422. The model demonstrated prediction accuracies of 99.1792% for the coefficient of variation (CV) of uniformly coated fabrics and 96.8877% for non-uniformly coated fabrics. Additionally, p-value analysis of all fabric samples yielded a result of 0.96044, indicating no statistically significant difference between the predicted and actual values. The proposed CNN-based model can accurately evaluate the electrical uniformity of conductive fabrics, showing potential for contributing to quality control and process optimization in production.

Template Quality Dependent Conversion Synthesis of Boron Nitride Coated Graphene Hybrid Aerogels for Ultrasensitive and Selective Ammonia Sensing

AbstractRecently, hexagonal boron nitride (h‐BN) nanomaterials, e.g., nanosheets and nanotubes, have been predicted to be effective materials for reversible gas adsorption with high selectivity once charged. However, despite the encouraging theoretical predictions, sensing with h‐BN is difficult to realize experimentally due to its electrically insulating nature stemming from its large band gap. In this research, the controlled synthesis of high surface area hybrid h‐BN/graphene aerogel is reported, using high‐quality graphene as a template, and its application for selective gas sensing. It is discovered for the first time in this system that the difficulty of conversion in template synthesis of h‐BN is positively correlated with the quality of the carbon template, an observation that is verified on both graphene nanosheets and carbon nanotubes. The application of this hybrid material for gas sensing yields ppb level of detection limit and high selectivity for NH3. Through density functional theory calculations, the adsorption energy and charge transfer between NH3 molecules and aerogel are greatly enhanced. Therefore, this innovative approach promises new possibilities for the application of h‐BN in gas sensing, with the potential to play a significant role in gas capture, environmental monitoring, and other related fields.

Urchin-like γ-MnO2/Carbon Nanotubes as an Efficient Cathode Catalyst for Durable Solid-State Lithium and Sodium-CO2 Batteries

Urchin-like γ-MnO₂/Carbon Nanotubes as an Efficient Cathode Catalyst for Durable Solid-State Lithium and Sodium-CO₂ Batteries