Assembly Of Carbon Nanotubes Research Articles

Hydrogen Bond-Driven Hierarchical Assembly of Single-Walled Carbon Nanotubes for Ultrahigh Textile Capacity.

Hydrogen-bond-driven 1D assembly of carbon nanotubes dispersed in organic solvents remains challenging owing to difficulties associated with achieving high oxidation levels and uniform dispersion. Here, we introduced a bioinspired wet-spinning method that utilizes highly oxidized single-walled carbon nanotubes dispersed in organic solvents without superacid or dispersants. By incorporating submicrometer-sized graphene oxide nanosheets, we facilitated the ejection of 1.5 wt % spinning dopes, which formed an interconnected network via hydrogen bonding during coagulation. In this process, swollen carbon nanotube fibers from a multihole spinneret were merged into a single filament via interdigitation, similar to the process observed in spider silk spinning. The resulting interdigitated and conducting carbon nanotube fibers with hierarchical structures serve as versatile textile electrodes in applications such as sensitive textile gas sensors and excellent textile supercapacitors, exhibiting a capacitance of 320 F g-1 at an extremely high current density of 32 A g-1. We establish a robust platform for textile electronics, highlighting the significant potential of our bioinspired approach.

Ultrathin MWCNT/Ti3C2Tx Hybrid Films for Electromagnetic Interference Shielding.

The disordered assembly and low conductivity of carbon nanotubes are the main problems that limit the application of electromagnetic interference (EMI) shielding. In this work, an ordered lamellar assembly structure of multiwalled carbon nanotube/Ti3C2Tx (MWCNT/Ti3C2Tx) hybrid films was achieved by vacuum-assisted filtration through the hybridization of Ti3C2Tx nanosheets and carbon nanotubes, where carbon nanotubes were tightly sticking on the surface of Ti3C2Tx nanosheets via physical adsorption and hydrogen bonding. Compared with the pure carbon nanotubes films, the hybrid MWCNT/Ti3C2Tx films achieved a significant improvement in conductivity of 452.5 S/cm and EMI shielding effectiveness (SE) of 44.3 dB under 50 wt% Ti3C2Tx with a low thickness (8.6 μm) and orderly lamellar stacking structure, which finally resulted in high specific SE (SSE/t, SE divided by the density and thickness) of 55,603.1 dB∙cm2∙g-1.

DNA-Mediated Carbon Nanotubes Heterojunction Assembly.

Herein, we present a strategy for the controlled assembly of single-walled carbon nanotube (SWCNT) linear junctions mediated by DNA as a functional linker. We demonstrate this by employing SWCNTs of two different chiralities via the specific design of DNA sequences and chiral selection. Streptavidin and AuNP labeling of the SWCNT sidewalls demonstrate the presence of two different chirality within each individual CNT-DNA-CNT junction. These one-dimensional nanohybrids were further organized from solution to devices. The approach we developed is of general applicability for the assembly of functional nanohybrids based on carbon nanotubes toward functional applications.

(Invited) Carbon/Metal Hybrid Materials for Robust Biosensors Development

Carbon nanotubes (CNTs) are well known for their flexibility, electrical conductivity and chemical inertness, however their use as biorecognition elements is limited due to multiple fabrication and interface aspects. Among them those related to their uniformity and stability of the CNT assemblies employed as microelectrodes. Although CNTs have shown improved detection capabilities when employed as sensors, their lack of reliable connectivity to metal surfaces has compromised their long-term performance. This talk will report fundamental calculations and experimental studies for a robust chemical bond formation of open-ended vertically oriented CNTs to copper metal surfaces. Theoretically, the nature of the bonding and the electrical resistance at the interface were determined. Experimentally, CNT bonding to metal surfaces was accomplished by grafting linker molecules to copper and gold surfaces using diazonium chemistry, for subsequent cross-linking to the proper functional groups on CNTs. These linkers were bonded to the open-ended CNTs while maintained their vertical orientation. The technique has also been applied for bonding functionalized sidewalls of CNTs to gold and other metal substrates. The application of these chemically bonded CNTs to nanostructured gold substrates as electrochemical sensors displayed high stability of the signal when exposed to oxidative conditions. Even after 540 h of exposure to a high oxidative potential, the current response remained stable, having negligible deviations between runs. Hydrogen peroxide detection using these hybrid materials involves an indirect enzyme-free oxidation mechanism, enabling their quantification at low potentials. The use of CNT/gold hybrid electrode materials allows for classifying the system as a fourth generation H2O2 sensor. Because of the low working potential, a 20-fold excess of fructose, creatinine, dopamine, uric acid, citric acid, and ascorbic acid did not interfere with hydrogen peroxide detection. Moreover, these carbon nanotube-based hybrid materials provide a large number of functionalization possibilities to employ them as electrode platforms for sensor development.

(Invited) High Temperature Effects on the Properties of Single-Chirality Carbon Nanotube Assemblies

Individual single-walled carbon nanotubes are quite thermally stable, and they exhibit narrowband thermal radiation due to sharp exciton resonance at high temperatures over 1000 K [1]. This phenomenon is expected to offer a new opportunity for utilizing exciton properties in thermophotovoltaic energy harvesting requiring excellent wavelength selective near-infrared thermal emitter [1,2]. For the realistic macroscale applications, it is necessary to utilize structure-separated single-chirality carbon nanotube assemblies that exhibit distinct exciton resonances in the optical spectra [3,4] at high temperatures. However, the effects of high temperature on the properties of high purity, single-chirality carbon nanotube assemblies have remained to be clarified. We will report on the effects of high temperature on the properties of single-chirality carbon nanotube assemblies, including the emergence of a new exciton absorption peak due to chirality-selective nanotube coalescence reactions [5].[1] T. Nishihara, A. Takakura, Y. Miyauchi, and K. Itami, Nat. Commun. 9, 3144 (2018). [2] S. Konabe, T. Nishihara, and Y. Miyauchi, Opt. Lett. 46, 3021 (2021). [3] T. Nishihara, A. Takakura, M. Shimasaki, K. Matsuda, T. Tanaka, H. Kataura, and Y. Miyauchi, Nanophotonics 11, 1011 (2022). [4] H. Wu, T. Nishihara, A. Takakura, K. Matsuda, T. Tanaka, H. Kataura, and Y. Miyauchi, Carbon 218, 118720 (2024). [5] A. Takakura, T. Nishihara, T. Tanaka, H. Kataura, and Y. Miyauchi, submitted.

Optimizing field-emission devices: Advancements in stability and performance with well-oriented and dense integrated carbon nanotube assemblies

Carbon nanotubes (CNTs) are attracting widespread interest as electron emitters due to their superior field emission properties. However, the correlation between the microstructural properties of CNTs and their electron emission performance has not been fully understood, limiting the optimization of their performance particularly in terms of device stability. Herein, we present highly oriented and densely integrated CNT assemblies as a cold cathode material with stable field electron emission. These assemblies were prepared via the floating catalyst chemical vapor deposition-based direct spinning method, constructing a fibrous structure with a hierarchical composition of individual CNTs and bundles within the microstructure. By varying the spinning rate during the winding process, we engineered the microstructure of the CNT assemblies. The CNT assemblies spun at high rates presented a relatively higher degree of orientation and packing density for both individual CNTs and bundles, thus resulting in a thermally and mechanically stable microstructure. Furthermore, the stable microstructure of these CNT assemblies translated into an almost consistent electric field under repeated electron emission cycles, well-revealing their impressive stability in field electron emission. Overall, the CNT assemblies with a stable microstructure enable efficient and stable field electron emission, offering a promising strategy for devising CNT-based field electron-emitting devices.

High-sensitivity label-free electrochemical genosensors for carbon nanotube plasmon-assisted detection of somatic mutations in nucleic acids from formalin-fixed paraffin-embedded tissues

Currently, molecular genetic testing of somatic point mutations in the genome of cancer tumors for targeted therapy requires high-performance tools for studies of spatial gene expression and spatial genome profiling in formalin-fixed paraffin-embedded (FFPE) tissue samples. We offer new high-performance label-free electrochemical impedimetric deoxyribonucleic-acid (DNA) nanosensors. The sensors based on a platform of crystalline carbon nanotube plasmonic assemblies are fabricated by the Langmuir–Blodgett deposition technique. The carbon-nanotube assemblies are suspended on nanoporous supports. Incorporation of fast Fourier transforms in the impedance spectroscopy led to the introduction of a new information parameter, the integral value of capacitance changes. The allele-sensitive assay based on plasmon-assisted effects in the assemblies of electrically active conjugates between DNA and few-walled carbon nanotubes has been used for discrimination of allele single-nucleotide polymorphisms (SNPs) of Kirsten Rat Sarcoma viral oncogene homologue (KRAS gene). Using 19- and 20-mer single-stranded (ss) probe oligonucleotides and 35- and 47-mer toehold probes, we explored the probe length and the target location. The genotyping technology allows discrimination of single-nucleotide variations in the target 35-base oligonucleotide at the attomolar concentration level. Human genomic DNAs were isolated from FFPE colorectal cancer tumor tissue samples. The KRAS-gene exon 2, codon 12, c.35G>A mutation has been successfully discriminated in the genomic DNAs with a significance level, P, of 0.001–0.02. The assay has a sensitivity with 0.33-ng/ml limit of detection (LOD) for native genomic DNA.

Nonlinear absorption of Hermite cosh-Gaussian laser beam in an assembly of cylindrical carbon nanotubes embedded with static magnetic field

Nonlinear absorption of Hermite cosh-Gaussian laser beam in an assembly of cylindrical carbon nanotubes embedded with static magnetic field

(Invited) Assembly of Carbon Nanotubes Heterostructures Down to Single-Particle Control

We will present different chemical strategies for the in-solution assembly of single walled carbon nanotube (SWCNT)-based heterostructures, down to single-particle control and resolution. In particular, we interfaced SWCNTs to inorganic semiconducting nanoparticles and nanocrystals, perovskites, as well as metal nanoparticles and nanowires. We developed various approaches towards this end, from the selective and differential functionalisation of CNTs terminal ends with distinct individual nanomoieties , to the use of nanotubes as templates for the growth of nanomaterials on their sidewall or in their cavity. Solution-processed optoelectronic devices were fabricated employing the aforementioned nanohybrids, displaying various sensitivity to a broad range of illumination wavelengths.

(Invited) Optimising CNT-FET Biosensor Design: Tuning Biomolecule Interfaces for Aptamer-Biomarker Sensing and Beta-Lactamase Detection

We will present different strategies to control the assembly of single walled carbon nanotube (SWCNT)-biomolecule interfaces towards the fabrication of bioelectronic devices, with a focus on the real-time biosensors with engineered aptamer and protein interfacing. In particular, we will report on the fabrication of nanoscale biosensing devices designed to present biorecognition moieties (aptamers and proteins) in defined orientations; this allowed us to control the local electrostatic surface presented within the Debye length, and thus modulate the conductance gating effect upon binding incoming targets, from biomarkers associated to stress and (neuro) trauma, to classes of enzyme relevant to antimicrobial resistance (beta-lactamases).Our efforts focused in particular on using beta-lactamase binding protein (BLIP2) as receptor due to its potential as a biosensor for the most common antibiotic degrading enzymes, the beta-lactamases (BLs). Attaching BLIP2 at single designed residues positions directly to SCNTs using genetically encoded phenyl azide photochemistry, our devices were able to successfully detect the two different BLs, TEM-1 and KPC-2. The changes in conductance closely matched the predicted electrostatic profile sampled by the CNTs on BL binding.These studies highlight the key role transducer-biomolecule interfaces play in biosensing devices, and the need to control and tune by design the electrostatic gating, for more effective and optimal CNT-FET biosensor construction.

Enhanced solar-driven steam generation and water purification using 3D arch solar evaporators

Steam generation strategy through solar-driven evaporators has now been widely recognized as one of the effective means to relieve the global fresh water crisis. Reducing heat loss has shown to be an effective way to improve the evaporation efficiency which has been overlooked in three-dimensional (3D) evaporators in the past. Herein, a superhydrophilic photothermal fabric was developed by the layer-by-layer assembly of carbon nanotubes followed by dip-coating with polyvinyl alcohol. The as-obtained photothermal fabric was designed as a 3D arch solar evaporator (ASE). The arch structure allowed the photothermal fabric to achieve double-sided water evaporation and a well-balanced saline water supply by controlling the height of the ASE. The ASE effectively captured the incident sunlight and demonstrated extraordinary thermal management performance, resulting in a saline water evaporation flux of 1.015–3.400 kg m−2 h−1 under 1 sun irradiation for 6 h. In addition, the proposed ASE exhibited excellent water purification for high salinity saline water, colored wastewater, and heavy metal wastewater. This work provides new insights into emerging solar steam generation systems by regulating the saline water supply balance.

Understanding the Molecular Assemblies of Single Walled Carbon Nanotubes and Tailoring their Photoluminescence for the Next-Generation Optical Nanosensors

Understanding the Molecular Assemblies of Single Walled Carbon Nanotubes and Tailoring their Photoluminescence for the Next-Generation Optical Nanosensors

Underwater Thermoacoustic Generation by a Hierarchical Tetrapodal Carbon Nanotube Network.

Solid-state fabricated carbon nanotube (CNT) sheets have shown promise as thermoacoustic (TA) sound generators, emitting tunable sound waves across a broad frequency spectrum (1-105 Hz) due to their ultralow specific heat capacity. However, their applications as underwater TA sound generators are limited by the reduced mechanical strength of CNT sheets in aqueous environments. In this study, we present a mechanically robust underwater TA device constructed from a three-dimensional (3D) tetrapodal assembly of carbon nanotubes (t-CNTs). These structures feature a high porosity (>99.9%) and a double-hollowed network of well-interconnected CNTs. We systematically explore the impact of different dimensions of t-CNTs and various annealing procedures on sound generation performance. Furnace-annealed t-CNTs, in contrast to directly resistive Joule heating annealing, provide superior, continuous, and homogeneous hydrophobicity across the surface of bulk t-CNTs. As a result, the t-CNTs-based underwater TA device demonstrates stable, smooth, and broad-spectrum sound generation within the frequency range of 1 × 102 to 1 × 104 Hz, along with a weak resonance response. Furthermore, these devices exhibit enhanced and more stable sound generation performance at nonresonance frequencies compared to regular CNT-based devices. This study contributes to advancing the development of underwater TA devices with characteristics such as being nonresonant, high-performing, flexible, elastically compressible, and reliable, enabling operation across a broad frequency range.

Assembly and Alignment of High Packing Density Carbon Nanotube Arrays Using Lithographically Defined Microscopic Water Features.

High packing density aligned arrays of semiconducting carbon nanotubes (CNTs) are required for many electronics applications. Past work has shown that the accumulation of CNTs at a water-solvent interface can drive array self-assembly. Previously, the confining interface was a large-area, macroscopic feature. Here, we report on the CNT assembly on microscopic water features. Water microdroplets are formed on 10-100 μm wide hydrophilic stripes patterned on a substrate. Exposure to CNTs dispersed in solvent accumulates CNTs at the microdroplet-solvent interface, driving their alignment and deposition at the microdroplet-solvent-substrate contact line. Compared with macroscopic methods in which the contact line uncontrollably moves across the substrate as it is pulled out of the liquids, the hydrophilic patterns and microdroplets allow pinning of the contact line. As CNTs deposit, the contact line self-translates, allowing for dense CNT packing. We realize monolayer CNT arrays aligned within ±3.9° at density of 250 μm-1 and field effect transistors with a high current density of 1.9 mA μm-1 and transconductance of 1.2 mS μm-1 at -0.6 V drain bias and 60 nm channel length.

Flexible Bifunctional Electrode for Alkaline Water Splitting with Long-Term Stability.

Progress in electrochemical water-splitting devices as future renewable and clean energy systems requires the development of electrodes composed of efficient and earth-abundant bifunctional electrocatalysts. This study reveals a novel flexible and bifunctional electrode (NiO@CNTR) by hybridizing macroscopically assembled carbon nanotube ribbons (CNTRs) and atmospheric plasma-synthesized NiO quantum dots (QDs) with varied loadings to demonstrate bifunctional electrocatalytic activity for stable and efficient overall water-splitting (OWS) applications. Comparative studies on the effect of different electrolytes, e.g., acid and alkaline, reveal a strong preference for alkaline electrolytes for the developed NiO@CNTR electrode, suggesting its bifunctionality for both HER and OER activities. Our proposed NiO@CNTR electrode demonstrates significantly enhanced overall catalytic performance in a two-electrode alkaline electrolyzer cell configuration by assembling the same electrode materials as both the anode and the cathode, with a remarkable long-standing stability retaining ∼100% of the initial current after a 100 h long OWS run, which is attributed to the "synergistic coupling" between NiO QD catalysts and the CNTR matrix. Interestingly, the developed electrode exhibits a cell potential (E10) of only 1.81 V with significantly low NiO QD loading (83 μg/cm2) compared to other catalyst loading values reported in the literature. This study demonstrates a potential class of carbon-based electrodes with single-metal-based bifunctional catalysts that opens up a cost-effective and large-scale pathway for further development of catalysts and their loading engineering suitable for alkaline-based OWS applications and green hydrogen generation.

An integrally bilayered flexible cathode woven from CNTs for homogeneous hosting and fast electrocatalytic conversion of Li2O2 in Li-O2 battery

Due to the ultrahigh theoretical energy density, Li-O2 batteries are considered as potential candidates for power accessories for wearable electronic devices. An effective oxygen-breathing cathode is essential to enable high cyclic stability in Li-O2 batteries. Herein, an integrally bilayered, freestanding flexible Li-O2 battery cathode is constructed by in-situ growth of a layer of microflowers (which is an assembly of nitrogen-doped carbon nanotubes embedded with cobalt nanoparticles) on the surface of a CNT-interwoven film. Owing to the integrally bilayered structural feature and its compositional merits, such three-dimensionally conductive network provides a large space and surface area for homogeneous hosting and also enables efficient electrocatalytic conversion of the insulating Li2O2 solids. Thus obtained cathode delivers a large full capacity of 8.03 mAh cm−2; it also exhibits a low charge potential of approximately 3.6 V and excellent cyclic stability for stable operation up to nearly 2 months at a capacity of 0.1 and 1 mAh cm−2. Moreover, being flexible and binder-free, the cathode is highly robust, which can withstand repetitive folding and unfolding. A co-axial Li-air battery was fabricated accordingly, which exhibits excellent tolerance to bending deformation, showing great potential for application in flexible and wearable electronics.

Decreasing the environmental impact of carbon fibre production via microwave carbonisation enabled by self-assembled nanostructured coatings

The use of carbon fibre (CF)-based composites is of growing global importance due to their application in high-end sectors such as aerospace, automotive, construction, sports and leisure amongst others. However, their current high production cost, high carbon footprint and reduced production capability limit their use to high-performance and luxury applications. Approximately 50% of the total cost of CF production is due to the thermal conversion of polyacrylonitrile (PAN) precursor fibre (PF) to CF as it involves the use of high energy consumption and low heating efficiency in large furnaces. Looking at this scenario, this study proposes in the present study to use microwave (MW) heating to convert PF to CF. This is scientifically and technologically challenging since PF does not absorb microwave energy. While MW plasma has been utilised to carbonise fibres, it is the high temperature from the plasma that does the carbonisation and not the MW absorption of the fibres. Therefore, for the first time, this research shows how carbonisation temperatures of >1000 °C can be reached in a matter of seconds through the use of a novel microwave (MW) susceptor nanocoating methodology developed via a layer-by-layer assembly of multiwall carbon nanotubes (MWCNTs) on the PF surface. Remarkably, these CFs can be produced in an inexpensive domestic microwave and exhibit mechanical performance equivalent to CF produced using conventional heating. Additionally, this study provides a life cycle and environmental impact analysis which shows that MW heating reduces the energy demand and environmental impact of lignin-based CF production by up to 66.8% and 69.5%, respectively.Graphical

Fast liquid-free patterning of SWCNT films for electronic and optical applications

The development of new approaches to assembling carbon nanotubes in next-level architecture organization is one of the key directions in Nanomaterials Science. Meanwhile, the recent advances in the so-called rational design of thin single-walled carbon nanotube (SWCNT) films promise a significant improvement in the performance of electronic and optical devices. In this study, we propose a fast, efficient, and green method for the fabrication of 2D patterned SWCNT structures. This technique is based on the selective area deposition of SWCNTs synthesized in the aerosol (floating catalyst) CVD process. Such a liquid-free and one-step process beneficially distinguishes from existing alternative methods based on lithography on the filter or post-treatment lithography on already synthesized continuous films. We demonstrate a 12-fold improvement in the performance of patterned mesh-shaped SWCNT films used as transparent electrodes when compared to the continuous film. As a result, the sheet resistance at an overall 90 % transparency in the visible light range value of 62 Ω/□ was achieved. Moreover, transferred onto elastomer, the mesh-shaped SWCNT films were efficiently applied as tunable diffraction gratings in the THz range. We believe the technique proposed extends the possibilities of the aerosol CVD process for utilization in various applications.

Application and structure of carbon nanotube and graphene-based flexible electrode materials and assembly modes of flexible lithium-ion batteries toward different functions

Application and structure of carbon nanotube and graphene-based flexible electrode materials and assembly modes of flexible lithium-ion batteries toward different functions

Plasmon-associated DNA genotyping based on crystalline assemblies of metallic carbon nanotubes

Sensitivity and selectivity of modern electrochemical genotyping methods are insufficient to detect a single-oligonucleotide mismatch in low-concentration native DNA samples. Novel methods of tuning, controlling, and monitoring plasmon modes are necessary to achieve attomolar and higher sensitivity for the modern graphene-based transducers of molecular signals. The electrochemical DNA assay is promising one for applications in the molecular diagnostics of tumors with the genome single-nucleotide polymorphism (SNP) for simultaneously discriminating both wild-type and mutant alleles of the gene in very small concentrations. We offer the plasmon-associated DNA-genotyping method based on the screening effects in assemblies of Raman-optically active conjugates comprising DNA and metallic carbon nanotubes. The impedimetric DNA sensors of non-Faradaic type based on the plasmonic screening effect can be more sensitive than the Raman optical transducer based on Raman DNA optical activity resulting in the plasmon resonance due to liability of the Raman transducer parameters to environmental influence.