Single-walled Carbon Nanotubes Research Articles

Terahertz SWNT-based fluidic chip for sensing enantioselectivity

Enantioselectivity sensing is crucial in biological systems due to the impact of the selective behaviors of chiral compounds on their targets. Conventional approaches for detecting enantioselectivity are restricted by the presence of high phonon energy, complex device manufacturing processes, low sensitivity, and the need for large sample sizes. Here, we propose a single-walled carbon nanotube (SWNT)-based fluidic chip that uses terahertz (THz) optical rotatory dispersion (ORD) spectroscopy to detect tartaric acids with high selectivity in very small amounts of liquid. The chip is composed of tailored U-shaped metasurfaces that show significant amplification of the near-field around the typical peaks of tartaric acids in the ORD spectrum. Additionally, it includes subwavelength gratings made of SWNTs, allowing for accurate detection of polarization angles. The limit of detection (LOD) for D-tartaric acid and L-tartaric acid are 17.9 mg/L and 11.0 mg/L, respectively. The sensitivities are superior to those of UV ORD or CD spectrometers. Furthermore, the presence of tartaric acid in wine is effectively identified, with a LOD of 25.60 mg/L. This technological development provides a significant improvement in chiral analysis by allowing for quick, highly sensitive, and precise detection of enantiomers.

Aerosol-Synthesized Surfactant-Free Single-Walled Carbon Nanotube-Based NO2 Sensors: Unprecedentedly High Sensitivity and Fast Recovery.

This study pioneers a chemical sensor based on surfactant-free aerosol-synthesized single-walled carbon nanotube (SWCNT) films for detecting nitrogen dioxide (NO2). Unlike conventional CNTs, the SWCNTs used in this study exhibit one of the highest surface-to-volume ratios. They show minimal bundling without the need for surfactants and have the lowest number of defects among reported CNTs. Furthermore, the dry-transferrable and facile one-step lamination resultsin promising industrial viability. When applied to devices, the sensor shows excellent sensitivity (41.6% at 500ppb), rapid response/recovery time (14.2/120.8s), a remarkably low limit of detection (below ≈0.161ppb), minimal noise, repeatability for more than 50 cycles without fluctuation, and long-term stability for longer than 6months. This is the best performance reported for a pure CNT-based sensor. In addition, the aerosol SWCNTs demonstrate consistent gas-sensing performance even after 5000 bending cycles, indicating their suitability for wearable applications. Based on experimental and theoretical analyses, the proposed aerosol CNTs are expected to overcome the limitations associated with conventional CNT-based sensors, thereby offering a promising avenue for various sensor applications.

Efficient Electrochemical Microsensor for the Simultaneous Measurement of Hydrogen Peroxide and Ascorbic Acid in Living Brains.

Hydrogen peroxide (H2O2) and ascorbic acid (AA), acting as two significant indicative species, correlate with the oxidative stress status in living brains, which have historically been considered to be involved mainly in neurodegenerative disorders such as Alzheimer's disease, Huntington's disease, and Parkinson's disease (PD). The development of efficient biosensors for the simultaneous measurement of their levels in living brains is vital to understand their roles played in the brain and their interactive relationship in the progress of these diseases. Herein, a robust ratiometric electrochemical microsensor was rationally designed to realize the determination of H2O2 and AA simultaneously. Therefore, a specific probe was designed and synthesized with both recognition units responsible for reacting with H2O2 to produce a detectable signal on the microsensor and linkage units helping the probe modify onto the carbon substrate. A topping ingredient, single-walled carbon nanotubes (SWCNTs) was added on the surface of the electrode, with the purpose of not only facilitating the oxidation of AA but also absorbing methylene blue (MB), prompting to read out the inner reference signal. This proposed electrochemical microsensor exhibited a robust ability to real-time track H2O2 and AA in linear ranges of 0.5-900 and 10-1000 μM with high selectivity and accuracy, respectively. Eventually, the efficient electrochemical microsensor was successfully applied to the simultaneous measurement of H2O2 and AA in the rat brain, followed by microinjection, and in the PD mouse brain.

Carbon Nanomaterials for Plant Priming through Mechanostimulation: Emphasizing the Role of Shape.

The use of nanomaterials to improve plant immunity for sustainable agriculture is gaining increasing attention; yet, the mechanisms involved remain unclear. In contrast to metal-based counterparts, carbon-based nanomaterials do not release components. Determining how these carbon-based nanomaterials strengthen the resistance of plants to diseases is essential as well as whether shape influences this process. Our study compared single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) infiltration against the phytopathogen Pseudomonas syringae pv tomato DC3000. Compared with plants treated with GO, plants primed with SWNTs showed a 29% improvement in the pathogen resistance. Upon nanopriming, the plant displayed wound signaling with transcriptional regulation similar to that observed under brushing-induced mechanostimulation. Compared with GO, SWNTs penetrated more greatly into the leaf and improved transport, resulting in a heightened wound response; this effect resulted from the tubular structure of SWNTs, which differed from the planar form of GO. The shape effect was further demonstrated by wrapping SWNTs with bovine serum albumin, which masked the sharp edges of SWNTs and resulted in a significant decrease in the overall plant wound response. Finally, we clarified how the local wound response led to systemic immunity through increased calcium ion signaling in distant plant areas, which increased the antimicrobial efficacy. In summary, our systematic investigation established connections among carbon nanomaterial priming, mechanostimulation, and wound response, revealing recognition patterns in plant immunity. These findings promise to advance nanotechnology in sustainable agriculture by strengthening plant defenses, enhancing resilience, and reducing reliance on traditional chemicals.

Large-Area Flexible Carbon Nanofilms with Synergistically Enhanced Transmittance and Conductivity Prepared by Reorganizing Single-Walled Carbon Nanotube Networks.

Large-area flexible transparent conductive films (TCFs) are highly desired for future electronic devices. Nanocarbon TCFs are one of the most promising candidates, but some of their properties are mutually restricted. Here, a novel carbon nanotube network reorganization (CNNR) strategy, that is, the facet-driven CNNR (FD-CNNR) technique, is presented to overcome this intractable contradiction. The FD-CNNR technique introduces an interaction between single-walled carbon nanotube (SWNT) and Cu─-O. Based on the unique FD-CNNR mechanism, large-area flexible reorganized carbon nanofilms (RNC-TCFs) are designed and fabricated with A3-size and even meter-length, including reorganized SWNT (RSWNT) films and graphene and RSWNT (G-RSWNT) hybrid films. Synergistic improvement in strength, transmittance, and conductivity of flexible RNC-TCFs is achieved. The G-RSWNT TCF shows sheet resistance as low as 69Ωsq-1 at 86% transmittance, FOM value of 35, and Young's modulus of ≈45MPa. The high strength enables RNC-TCFs to be freestanding on water and easily transferred to any target substrate without contamination. A4-size flexible smart window is fabricated, which manifests controllable dimming and fog removal. The FD-CNNR technique can be extended to large-area or even large-scale fabrication of TCFs and can provide new insights into the design of TCFs and other functional films.

On comparative analysis of graph entropies of symmetrical carbon nanotube Y-junctions

Entropy is crucial in statistical mechanics, thermodynamics, and information theory as it measures a system’s level of randomness or disorder. Entropy is widely used in mathematical chemistry and computational physics to predict the behavior of a system under various conditions. Among numerous carbon nanotube structures, three-terminal carbon nanotube junctions are important structures not only for electrical but also for mechanical appliances. Recently, significant attention has been given to the understanding of carbon nanotube junctions. This research paper focuses on calculating graph entropies based on Zagreb indices for symmetrical single-walled armchair carbon nanotube Y − junctions and comparing the index-entropies of these junctions. The study aims to demonstrate the behavior of the nanotube Y − junctions by adding atoms at the end of the tubes.

Solution-Processable Low-Voltage Carbon Nanotube Field-Effect Transistors with High-k Relaxor Ferroelectric Polymer Gate Insulator.

Achieving energy-efficient and high-performance field-effect transistors (FETs) is one of the most important goals for future electronic devices. This paper reports semiconducting single-walled carbon nanotube FETs (s-SWNT-FETs) with an optimized high-k relaxor ferroelectric insulator P(VDF-TrFE-CFE) thickness for low-voltage operation. The s-SWNT-FETs with an optimized thickness (~ 800 nm) of the high-k insulator exhibited the highest average mobility of 14.4 cm2V-1s-1at the drain voltage (ID) of 1 V, with a high current on/off ratio (Ion/off>105). The optimized device performance resulted from the suppressed gate leakage current (IG) and a sufficiently large capacitance (> 50 nFcm-2) of the insulating layer. Despite the extremely high capacitance (> 100 nFcm-2) of the insulating layer, an insufficient thickness (< 450 nm) induces a high IG, leading to reduced IDand mobility of s-SWNT-FETs. Conversely, an overly thick insulator (> 1200 nm) cannot introduce sufficient capacitance, resulting in limited device performance. The large capacitance and sufficient breakdown voltage of the insulating layer with an appropriate thickness significantly improved p-type performance. However, a reduced n-type performance was observed owing to the increased electron trap density caused by fluorine proportional to the insulator thickness. Hence, precise control of the insulator thickness is crucial for achieving low-voltage operation with enhanced s-SWNT-FET performance.

Investigation of electromagnetic interference shielding performance of ultra-high-performance mortar incorporating single-walled carbon nanotubes and steel fiber

For security amenities and key infrastructure, construction materials with extraordinary mechanical, durability, and electromagnetic interference (EMI) shielding performance are essential. This study investigates the EMI shielding performance of ultra-high performance mortar (UHPM) incorporating single-walled carbon nanotubes (SWCNT) and steel fibers. Currently, no such work is present in the existing literature. Eight mixtures were prepared with varying SWCNT dosages (0%–0.03 % by weight of cement) and steel fiber additions (1.2 % of the volume of the UHPM mixture). The performance of UHPM incorporating SWCNT and steel fibers was evaluated through flow diameter, compressive strength, flexural strength, Schmidt hardness, ultrasonic pulse velocity, EMI shielding performance, and scanning electron microscopy analysis tests. It is observed that increasing the SWCNT content enhances the compressive strength, flexural strength, ultrasonic pulse velocity, and Schmidt hardness of UHPM. The addition of steel fibers further enhances compressive (up to 22 %) and flexural (up to 92 %) strengths. In terms of the transmittance behavior, the improved EMI shielding performance of UHPM with the increasing SWCNT content is observed prominently at high electromagnetic frequencies (i.e., 2500 MHz–5100 MHz). However, the improved shielding performance is observed to be quite low, limited to 10 dB. Moreover, combining steel fibers and SWCNT enhances the EMI shielding performance of UHPM in terms of the transmittance behavior. As a result, UHPM incorporating SWCNT and steel fibers behaves as an absorbent material, shielding a significant amount of energy, approximately 45 dB, at a frequency of 5000 MHz. Based on the results, UHPM incorporating SWCNT and steel fibers can be used effectively as EMI shielding material. The findings of this study will enhance the practical applications of UHPM incorporating SWCNT and steel fibers.

Stochastic analysis for the embedded single-walled carbon nanotube under random vibrations

Stochastic analysis for the embedded single-walled carbon nanotube under random vibrations

Construction of Hierarchical Conductive Networks for LiNi0.8Mn0.1Co0.1O2 Cathode toward Stable Cycling at High Areal Mass Loadings.

Realizing high-performance thick electrodes is considered as a practical strategy to promote the energy density of lithium-ion batteries. However, establishing effective transport pathways for both lithium-ions and electrons in a thick electrode is very challenging. This study develops a hierarchical conductive network structure for constructing high-performance NMC811 (LiNi0.8Mn0.1Co0.1O2) cathode toward stable cycling at high areal mass loadings. The hierarchical conductive networks are composed of a Li+/e- mixed conducting interface (lithium polyacrylate/hydroxyl-functionalized multiwalled carbon nanotubes) on NMC811 particles, and a segregated network of single-walled carbon nanotubes in the electrode, without any additional binders or carbon black. Such strategy endows the NMC811 cathode (up to 250µm and 50mg cm-2) with low porosity/tortuosity, ultrahigh Li+/e- conductivities and excellent mechanical property at low carbon nanotube content (1.8 wt%). It significantly improves the electrochemical reaction homogeneity along the electrode depth, meanwhile effectively inhibits the side reactions at the electrode/electrolyte interface and cracks in the NMC particles during cycling. This work emphasizes the crucial role of the electronic/ionic cooperative transportation in the performance deterioration of thick cathodes, and provide guidance for architecture optimization and performance improvement of thick electrodes toward practical applications, not just for the NMC811 cathode.

Thermal inspection of hybrid nanofluid flows over a stretched cylinder at an oblique stagnation point with variable characteristics

AbstractThe enhanced thermal characteristics of hybrid nanofluids make them more versatile compared to conventional fluids. These improved thermal properties render hybrid nanomaterials highly practical for a wide range of applications, including solar systems, energy production, and cooling processes. In line with this perspective, the current study concentrates on evaluating the thermal performance of two unique hybrid nanofluid flows that impinge obliquely on a stretched cylinder. Two base fluids, FC‐77 and a binary mixture of water and ethylene glycol (50:50)%, have been considered, with the addition of nanoparticles such as single‐walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). The said model's novelty is enhanced by the temperature dependent viscosity and thermal conductivity. Appropriate transformations are applied to derive a system of ordinary differential equations (ODEs), which are then solved numerically using the bvp4c method. A thorough examination is conducted on the physical phenomenon of pertinent parameters, accompanied by graphical representations. The results revealed that, for the FC‐77 coolant‐based hybrid nanofluid, mounting the particle volume fraction leads to a significant reduction in temperature distribution. Additionally, it is perceived that the presence of a variable viscosity parameter causes a reduction in the surface drag coefficient as well as the axial and tangential velocities. The validity of the proposed flow model is demonstrated by comparing the results with those from an earlier study.

Pharmacogenomic Studies of Antiviral Drug Favipiravir

In this work, we conducted a study of the interaction between DNA and favipiravir (FAV). This chemotherapeutic compound is an antiviral drug for the treatment of COVID-19 and other infections caused by RNA viruses. This paper examines the electroanalytical characteristics of FAV. The determined concentrations correspond to therapeutically significant ones in the range of 50–500 µM (R2 = 0.943). We have shown that FAV can be electro-oxidized around the potential of +0.96 V ÷ +0.98 V (vs. Ag/AgCl). A mechanism for electrochemical oxidation of FAV was proposed. The effect of the drug on DNA was recorded as changes in the intensity of electrochemical oxidation of heterocyclic nucleobases (guanine, adenine and thymine) using screen-printed graphite electrodes modified with single-walled carbon nanotubes and titanium oxide nanoparticles. In this work, the binding constants (Kb) of FAV/dsDNA complexes for guanine, adenine and thymine were calculated. The values of the DNA-mediated electrochemical decline coefficient were calculated as the ratio of the intensity of signals for the electrochemical oxidation of guanine, adenine and thymine in the presence of FAV to the intensity of signals for the electro-oxidation of these bases without drug (S, %). Based on the analysis of electrochemical parameters, values of binding constants and spectral data, intercalation was proposed as the principal mechanism of the antiviral drug FAV interaction with DNA. The interaction with calf thymus DNA also confirmed the intercalation mechanism. However, an additional mode of interaction, such as a damage effect together with electrostatic interactions, was revealed in a prolonged exposure of DNA to FAV.

An efficient approach toward production of near-zigzag single-chirality carbon nanotubes.

Synthesizing single-walled carbon nanotubes (SWCNTs) with a narrow chirality distribution is essential for obtaining pure chirality materials through postgrowth sorting techniques. Using carbon monoxide chemical vapor deposition, we devise a ruthenium (Ru) catalyst supported by silica for the bulk production of SWCNTs containing only a few (n, m) species. The result is attributed to the limited carbon dissociation on the supported Ru clusters, favoring the growth of only small-diameter SWCNTs at comparable growth rates. The resulting materials expedite high-purity single chirality separation using gel chromatography, leading to unprecedented yields of 3.5% for (9, 1) and 5.2% for (9, 2) nanotubes, which surpass those separated from HiPco SWCNTs by two orders of magnitude. This work sheds light on the large-quantity synthesis of SWCNTs with enriched species beyond near-armchair ones for their high-yield separation.

Examining Performance Loss Mechanisms in Lithium-Ion Batteries with the High-Voltage Mn-Rich Spinel Positive Electrodes

Abstract The high-voltage spinel, with the nominal composition of LiNi0.5-xMn1.5+xO4 (LNMO), could be a sustainable alternative to the layered-oxide positive electrodes used in lithium-ion batteries. However, commercial acceptance has been limited as LNMO cells display rapid performance loss during cycling. To examine reasons for this loss we prepared cells with LNMO-based positive and either graphite or lithium titanate (LTO) based negative electrodes. Our initial cells displayed high impedance and rapid impedance rise during cycling. Adding single walled carbon nanotubes in the positive lowered initial cell impedance but impedance increased during cycling because of coating delamination from the Al foil. Using a primed Al current collector solved the delamination problem: cells with this current collector showed only a small impedance rise. Regarding capacity, cells with the LTO negative showed higher initial capacities and smaller fade. Our data indicate that cell capacity retention is determined by reduction reactions at the negative electrode that lower capacity and oxidation reactions at the positive electrode that increase capacity: both types of reactions deplete the cell electrolyte during extended cycling. All things considered, species generated at high voltages, either in the electrolyte or at the LNMO electrode, drive cell capacity fade.

Facile fabrication of single-walled carbon nanotubes@cerium oxide composite sensing platform for ultrasensitive electrochemical analysis of methyl parathion

We proposed a simple and feasible strategy to fabricate the nano-structured cerium oxide (CeO2) nanoparticles decorated single-walled carbon nanotubes networks (SWCNT@CeO2), which was utilized to fabricate the SWCNT@CeO2/GCE sensor for detecting methyl parathion (MP) with high sensitivity. SWCNT possessed the unique one-dimensional hollow nanostructure with excellent conductivity performance, which boosted the charge diffusion rate. CeO2 with good biocompatibility and high catalytic capacity could achieve the adsorption of MP molecules on the surface of sensing electrode due to the affinity of CeO2 nanoparticles towards the phosphate groups of MP. Furthermore, SWCNT could effectively make up for the inherent disadvantage of CeO2 nanoparticles in the term of electrical conductivity. The fabricated SWCNT@CeO2/GCE sensor achieved the ultrasensitive MP electrochemical analysis property (LOD: 9.12 nM). The satisfactory repeatability, reproducibility, anti-interference abilities were obtained at the fabricated sensor. Regarding the electrochemical detection of MP in real food samples, both satisfactory recovery rates of 87.68–107.31% and low RSD of 1.09–2.65% suggested the favorable application prospect of SWCNT@CeO2/GCE sensor in the field of pesticide residue analysis.

Freestanding MXene‐Scaffolded Film Cathodes Enable High‐Performance Flexible Zinc‐Ion Batteries

AbstractFlexible electronics are among the highest‐profile devices in today's world. The development of high‐capacity power supply with both flexibility and rate stability is in great demand yet remains highly challenging. Herein, for the first time the construction of freestanding films is reported by integrating α‐MnO2 nanofibers in MXene (Ti3C2Tx) bonded single‐walled carbon nanotubes (SWCNTs) networks (named MXSC) through covalent bonding as binder‐free cathodes for high capacity and rate stability aqueous zinc‐ion battery. The film electrodes boast high electrical conductivity and decent flexibility for rolling and folding. The optimal MnO2@MXSC (α‐MnO2/SWCNTs/MXene = 10:40:60 by weight ratio) cathode contributes a steady specific capacity of 368 mAh g−1 at 1 A g−1 over 1000 cycles charge and discharge process, delivering a high energy density of 354 Wh kg−1 at a power density of 963 W kg−1. More importantly, the MnO2@MXSC cathode demonstrates exceptional cyclic performance after being bent 1000 times. The flexible Zn‐MnO2@MXSC thin film battery maintains its energy storage capability when subject to folding and cutting. Such outstanding abilities of this highly flexible rechargeable MnO2@MXSC cathode offer a unique perspective on powering wearable electronic devices.

T−n (n: 2.4∼2.56) temperature dependence of thermal resistance at single-walled carbon nanotubes/SiO2 interface at

The burgeoning significance of energy coupling at interfaces of nm dimension aligns seamlessly with the rapid strides made in micro/nanoelectronics. The nm-scale interface thermal resistance (ITR) is strongly affected by temperature but is poorly understood to date due to extreme challenges in nm-scale characterization. This work reports a pioneering and high-level study on how temperature affects the ITR of single-walled carbon nanotube (SWCNT)-SiO2 interface with a < 8 nm lateral dimension. From 297 to 77 K, the ITR is observed to increase from 530 to 725 to (1.56–1.74)×104 K·m·W−1. The reported ITRs at room temperature are in line with reported data for SWCNT/SiO2 interface. The ITR variation with temperature is compared with the prediction based on the phonon diffuse mismatch model (DMM). A great qualitative agreement is observed while the DMM under the Debye approximation of linear dispersion underestimates the ITR. Our ITR dependency on temperature takes the form of T−n where n is found to be 2.4 and 2.56 for two different locations of the sample. Such observation resembles the dependency of specific heat on temperature far below the Debye temperature. We introduce a concept termed as the effective interface energy transmission velocity (vi,eff) in an attempt to rule out the role of specific heat in ITR-temperature dependence to uncover the intrinsic effect of temperature on interface energy coupling. Very interestingly, vi,eff shows little variation over a wide temperature range for various reported interfaces. Further exploration and refinement of this concept is expected in forthcoming research endeavors.

Molecular Dynamics Study of Nanoribbon Formation by Encapsulating Cyclic Hydrocarbon Molecules inside Single-Walled Carbon Nanotube.

Carbon nanotubes filled with organic molecules can serve as chemical nanoreactors. Recent experimental results show that, by introducing cyclic hydrocarbon molecules inside carbon nanotubes, they can be transformed into nanoribbons or inner tubes, depending on the experimental conditions. In this paper, we present our results obtained as a continuation of our previous molecular dynamics simulation work. In our previous work, the initial geometry consisted of independent carbon atoms. Now, as an initial condition, we have placed different molecules inside a carbon nanotube (18,0): C5H5 (fragment of ferrocene), C5, C5+H2; C6H6 (benzene), C6, C6+H2; C20H12 (perylene); and C24H12 (coronene). The simulations were performed using the REBO-II potential of the LAMMPS software package, supplemented with a Lennard-Jones potential between the nanotube wall atoms and the inner atoms. The simulation proved difficult due to the slow dynamics of the H abstraction. However, with a slight modification of the parameterization, it was possible to model the formation of carbon nanoribbons inside the carbon nanotube.

Study of field distribution characteristics in CVD reactors and enhanced growth of SWNCT

The low efficiency of growing single-walled carbon nanotubes (SWCNT) poses a barrier to their application in high-performance electronic devices. However, it is difficult to control the uniform growth of SWCNT in a floating catalytic reactor due to the complex parameter control. Therefore, it is essential to enhance the growth of SWCNT in the floating catalyst chemical vapor deposition (FCCVD) process. In the present work, the influence of the reactive flow field on the growth of SWCNT, which is often neglected, is revealed. To address this issue, this work combines experiments and simulations to obtain the characteristics of field distribution within the reactor and the trend of the products. The results of the flow field analysis indicate that thermal buoyancy is the cause of SWCNT growth limitation in FCCVD. By weakening the thermal buoyancy, a homogeneous reaction field is obtained; vortices in the flow field are reduced or even disappear; the temperature field is more homogeneous, and, importantly, the crystallinity of SWCNT is enhanced (IG/ID up to 20-fold). In addition, the decomposition process of the carbon source is also enhanced, thus suppressing the generation of by-products. Based on the results of the small tube experiments, both the increase in temperature and the decrease in residence time increased IG/ID. Furthermore, the distributions of the maximum and minimum diameters in SWCNT imply variations in the growth modes of SWCNT at different temperatures.

Adsorption of formamide on pure, Al-, N-doped, and Al/N co-doped (8, 0) single-wall carbon nanotubes: a DFT study

Adsorption of formamide on pure, Al-, N-doped, and Al/N co-doped (8, 0) single-wall carbon nanotubes: a DFT study