Carbon Nanotube Arrays Research Articles

A 3D electrochemical biosensor based on Super-Aligned Carbon NanoTube array for point-of-care uric acid monitoring

Uric acid analysis is extremely important for gout prognosis, diagnosis and treatment. Previous technologies either lack specificity or exhibit poor performance, and thus could not meet the need of Point-of-Care (POC) uric acid monitoring. Here we present for the first time, a novel electrochemical biosensor based on 3D Super-Aligned Carbon NanoTube (SACNT) array to facilitate POC uric acid monitoring. The working electrode of the biosensor is composed of an orderly 3D SACNT array immobilized with uricase through a precipitation and crosslinking procedure. Such biosensor possesses a higher enzyme density, significantly larger contact area with reactants and could maintain the intact SACNT structure and its excellent conductivity after modification. The developed 3D SACNT array electrochemical biosensor benefits from high specific surface area, high electro-catalytic activity and large contact area with analytes, and demonstrates high sensitivity of 518.8 μA/(mM⋅cm2), wide linear range of 100–1000 μM and low limit of detection of 1 μM for uric acid. Dynamic uric acid monitoring has been achieved using the presented biosensor. And the obtained results in serum samples had no significant difference compared with those obtained using the FDA-approved electrochemical analyzer (Paired T-test, p > 0.05). These demonstrated that the technology can potentially be applied in POC monitoring of other biomolecules to improve prognosis, diagnosis and treatment outcomes of metabolic diseases.

Growth of Semiconducting Single-Walled Carbon Nanotubes Array by Precisely Inhibiting Metallic Tubes Using ZrO2 Nanoparticles.

Synthesis of high-quality single-walled carbon nanotubes arrays with pure semiconducting type is crucial for the fabrication of integrated circuits in nanoscale. However, the naturally grown carbon nanotubes usually have diverse structures and properties. Here the bicomponent catalyst using Au and ZrO2 is designed and prepared. The Au nanoparticle serves as the catalysts for carbon feedstock cracking and facilitating the nucleation of carbon nanotubes, whereas the close-connected ZrO2 forms a localized etching zone around Au by releasing lattice oxygen and to inhibit the nucleation of metallic carbon nanotubes precisely. The obtained single-walled carbon nanotubes array show a high semiconducting content of >96%,on the basis of good performance of field-effect transistor devices. And such building of localized etching zone is compatible with other catalyst systems as a universal and efficient method for the scalable production of semiconducting carbon nanotubes.

Hollow CoP nanoparticles embedded in carbon nanotube arrays as sodium ion battery anode with superior performance

We report a facile strategy to prepare carbon nanotubes embedded with hollow CoP nanoparticles arrays (H-CoP-NPs@CNTs) on flexible carbon cloth through hydrothermal synthesis, carbothermal reduction and phosphorization. The unique H-CoP-NPs@CNTs as free-standing sodium ion battery anodes exhibit remarkable electrochemical performances a specific capacity of 965.6 mA h g−1 for the 1st cycle and 63% retained capacity after rates test and 100 cycles at 100 mA g-1. The capacity retention rate is as high as 94.3% after different current sweeps. The excellent electrochemical performance can be attributed to the unique 1D hybrids nanoarrays structures, in which the pore inside and between hollow CoP nanoparticles provide more free spaces and active sites for favorable Na+ insertion/extraction, and the CNTs nanoarrays on flexible carbon cloth are able to improve the conductivity and maintain the structural integrity. Moreover, the 1D hybrids network also makes it favorable rapid ion/electron transport and enhanced rate performance.

Development of a CMOS-Compatible Carbon Nanotube Array Transfer Method.

Carbon nanotubes (CNTs) have, over the years, been used in research as a promising material in electronics as a thermal interface material and as interconnects amongst other applications. However, there exist several issues preventing the widespread integration of CNTs onto device applications, e.g., high growth temperature and interfacial resistance. To overcome these issues, a complementary metal oxide semiconductor (CMOS)-compatible CNT array transfer method that electrically connects the CNT arrays to target device substrates was developed. The method separates the CNT growth and preparation steps from the target substrate. Utilizing an alignment tool with the capabilities of thermocompression enables a highly accurate transfer of CNT arrays onto designated areas with desired patterns. With this transfer process as a starting point, improvement pointers are also discussed in this paper to further improve the quality of the transferred CNTs.

High-performance refractive index sensor for oil derivatives based on MWCNT photonic crystal microcavity

In this paper, we propose a new all-optical sensor based on a two-dimensional (2D) regular array of multi-walled carbon nanotubes (MWCNTs) for the refractive index sensing of oil derivatives, for the first time. The interaction of optical wave with the desirable oil derivatives is enhanced using the slow light effect that makes the group velocity go down. We consider the geometric feature for the proposed sensor structure as a photonic crystal (PhC) with a line defect formed by missing some rows of MWCNT elements. The difference of refractive index △n = 0.1418 between Butanol (C4H10O) and Nitrobenzene (C6H5NO2) host materials results in a wavelength shift of 149 nm, and indicates a sensitivity of 1050 nm/RIU, which can be widely used for the bio/chemical detection and environmental monitoring. To achieve the physical stability of the proposed sensor, MWCNTs are considered to be grown in the AAO (Al2O3) template. By removing one or two rows of the MWCNTs and creating a linear defect within the sensor structure, whereas oil derivatives are injected into the defect area. We have achieved a sensitivity up to 870 nm/RIU. This proposed sensor with un-reactive structure of MWCNTs can be used in environments with high temperature and pressure such as oil refinery industry and other chemical processes industries under wide range of different reaction conditions.

Tailoring the d-band center of N-doped carbon nanotube arrays with Co4N nanoparticles and single-atom Co for a superior hydrogen evolution reaction

A 3D self-supported integrated electrode, consisting of heteroatomic nitrogen-doped carbon nanotube arrays on carbon cloth with confined ultrafine Co4N nanoparticles and a distribution of anchored single-atom Co, is fabricated via a cobalt-catalyzed growth strategy using dicyandiamide as the nitrogen and carbon source and a layered cobalt hydroxide-nitrate salt as the precursor. The abundance of exposed active sites, namely, the Co4N nanoparticles, single-atom Co, and heteroatomic N-doped carbon nanotubes, and multiple synergistic effects among these components provide suitable tailoring of the d-band center for facilitating vectorial electron transfer and efficient electrocatalysis. Benefiting from the merits of its structural features and electronic configuration, the prepared electrode exhibits robust performance toward the hydrogen evolution reaction with overpotentials of only 78 and 86 mV at 10 mA cm−2 in acidic and basic electrolytes, respectively. Density functional theory calculations and X-ray photoelectron spectroscopy valence band measurements reveal that the effective tailoring of the d-band center by Co4N nanoparticles plays a crucial role in optimizing the hydrogen adsorption free energy to a more thermoneutral value for efficient electrocatalysis.

Continuous water-water hydrogen bonding network across the rim of carbon nanotubes facilitating water transport for desalination

The development of membranes featuring carbon nanotubes (CNTs) have provided possibilities of next-generation solar desalination technologies. For solar desalination, the microstructures and interactions between the filter membrane and seawater play a crucial role in desalination performance. Understanding the mechanisms of water evaporation and ion rejection in confined pores or channels is necessary to optimize the desalting process. Here, using non-equilibrium molecular dynamics simulations, we found that continuous water-water hydrogen bonding network across the rims of CNTs is the key factor in facilitating water transport through CNTs. With the continuous hydrogen bonding network, the water flux is two times of that without the continuous hydrogen bonding network. In CNT arrays, each CNT transports water molecules and rejects salt ions independently. Based on these observations, using CNT arrays consisted with densely packed thin CNTs is the most advisable strategy for evaporation desalination, possessing high transport flux as well as maintaining high salt rejection.

High lithiophilic nitrogen-doped carbon nanotube arrays prepared by in-situ catalyze for lithium metal anode

Lithium metal has a very outstanding theoretical capacity (3860 mAh/g) and is one of the most superior anode materials for high energy density batteries. However, the uncontrollable dendrite growth and the formation of “dead lithium” are the important hidden dangers of short cycle life and low safety. However, the uncontrollable dendrite growth and the formation of dead lithium leads to short cycle life and hidden danger, which hinder its practical application. Controlling the nucleation and growth process of lithium is an effective strategy to inhibit lithium dendrite. Herein, a simple in situ self-catalytic method is used to construct nitrogen doped carbon nanotube arrays on stainless steel mesh (N-CNT@SS) as a lithium composite anode. The N-doped CNTs provide a great number of N-functional groups, which enhance the lithiophilic of anode and provide a large number of uniform nucleation sites, hence it has excellent structural stability for cycles. The arrays provide neat lithium-ion transport channels to uniform lithium-ion flux and inhibits dendrite generation, revealed by the COMSOL multi-physics concentration field simulation. The N-CNT@SS composite anode sustain stable at 98.9% over 300 cycles at 1 mA/cm2. N-CNT@SS as the anode is coupled LiFePO4 (LFP) as the cathode construct a full battery, demonstrating excellent cycling stability with a capacity of 152.33 mAh/g and capacity retaining ratio of 95.4% after 100 cycles at 0.5 C.

Advances of CNT-based systems in thermal management

Effective thermal management has become extremely urgent for electronics due to the massive heat originated from the ever-rising power density. With the merits of high thermal conductivity, good chemical stability and desirable mechanical properties, carbon nanotubes (CNTs) are considered to have great potential to be widely used in heat dissipation devices. This article describes the progress on thermal conductivity of CNT-reinforced composites, aligned CNT materials (aligned CNT arrays, films/buckypapers and fibers) as high thermal conductors, experimental and theoretical results of CNT-substrate interface resistance, and utilizations of CNTs in the passive heat dissipation (natural convection, heat radiation, and phase-change heat transfer). Finally, the challenges and prospects are discussed to provide some hints in the future studies. It is believed that CNTs can play an important role in thermal management of electronics, especially in the portable electronic devices.

Controlled exciton–plasmon coupling in a mixture of ultrathin periodically aligned single-wall carbon nanotube arrays

We study theoretically the in-plane electromagnetic response and the exciton–plasmon interactions for an experimentally feasible carbon nanotube (CN) film system composed of parallel aligned periodic semiconducting CN arrays embedded in an ultrathin finite-thickness dielectric. For homogeneous single-CN films, the intertube coupling and thermal broadening bring the exciton and interband plasmon resonances closer together. They can even overlap due to the inhomogeneous broadening for films composed of array mixtures with a slight CN diameter distribution. In such systems, the real part of the response function is negative for a broad range of energies (negative refraction band), and the CN film behaves as a hyperbolic metamaterial. We also show that for a properly fabricated two-component CN film, by varying the relative weights of the two constituent CN array components, one can tune the optical absorption profile to make the film transmit or absorb light in the neighborhood of an exciton absorption resonance on-demand.

Substrate adhesion evolves non-monotonically with processing time in millimeter-scale aligned carbon nanotube arrays.

The advantageous intrinsic and scale-dependent properties of aligned nanofibers (NFs) and their assembly into 3D architectures motivate their use as dry adhesives and shape-engineerable materials. While controlling NF-substrate adhesion is critical for scaled manufacturing and application-specific performance, current understanding of how this property evolves with processing conditions is limited. In this report, we introduce substrate adhesion predictive capabilities by using an exemplary array of NFs, aligned carbon nanotubes (CNTs), studied as a function of their processing. Substrate adhesion is found to scale non-monotonically with process time in a hydrocarbon environment and is investigated via the tensile pull-off of mm-scale CNT arrays from their growth substrate. CNT synthesis follows two regimes: Mode I ('Growth') and Mode II ('Post-Growth'), separated by growth termination. Within 10 minutes of post-growth, experiments and modeling indicate an order-of-magnitude increase in CNT array-substrate adhesion strength (∼40 to 285 kPa) and effective elastic array modulus (∼6 to 47 MPa), and a two-orders-of-magnitude increase in the single CNT-substrate adhesion force (∼0.190 to 12.3 nN) and work of adhesion (∼0.07 to 1.5 J m-2), where the iron catalyst is found to remain on the substrate. Growth number decay in Mode I and carbon accumulation in Mode II contribute to the mechanical response, which may imply a change in the deformation mechanism. Predictive capabilities of the model are assessed for previously studied NF arrays, suggesting that the current framework can enable the future design and manufacture of high-value NF array applications.

Propagation of Surface Plasmon Waves along Multi Wall Carbon Nanotube with Gold Core

We have studied the propagation of surface plasmon waves along multiwalled carbon nanotube with gold core. We have modeled the shells of multiwalled carbon nanotube as impedance sheets with axially directed surface conductivity incorporating inter shell coupling in an integral equation approach. We have found that in low frequency regime optical interband transitions did not occur and guided waves propagated with low attenuation in an multiwalled carbon nanotube which has metallic shells. In the same frequency range the axial polarizability of a finite length multiwalled carbon nanotube has a resonant behavior due the antenna length matching effect. The shells with surface conductivity due to interband transitions suppressed guided wave propagation. Surface Plasmon wave propagation in a multiwalled carbon nanotube with gold core showed that in the near infrared and visible regime the shells behaved as lossy dielectric materials and suppressed surface wave propagation along the gold core. The electromagnetic characteristics of carbon nanotube based antennas have been examined in different frequency regime ranging from the microwave to the visible regime. Carbon nanotube has been demonstrated to play a crucial role connected electrically to planner periodic structures of single wall carbon nanotubes, carbon nanotube bundles and carbon nanotube arrays. The inter shells interaction leaded to inter shell electron tunneling or hopping. Fermi momentum of two incommensurable shells do not coincide within the first Brillouin zone and the inter shell tunneling vanished. In the presence of localized defects inter shell conduction increased and defectfree shells were managed by neglecting intershell conduction. We have used microscopic model for multiwalled carbon nanotube and radiation characteristics were determined by its waveguiding properties, the dispersion equation for guided wave propagation on an infinitely long multiwall carbon nanotube. We have found that the guided wave has strong retardation and high attenuation so that the frequency of a geometric resonance is not connected to the free space wave length but to a shorter effective wavelength that depends on the material properties. The obtained results were compared with the previously obtained results and were found in good agreement.

Carbon nanotube arrays as monolayer nanoscale membrane for enhanced desalination

Carbon nanotube arrays as monolayer nanoscale membrane for enhanced desalination

Исследование массива вертикально-ориентированных многостенных углеродных нанотрубок для абсолютно черного тела

An array of vertically oriented multi-walled carbon nanotubes (VOMWCNT), obtained by chemical vapor deposition (CVD) on a silicon substrate without preliminary catalyst deposition, has been comprehensively investigated. The synthesis was carried out for 30 minutes in the reactor of a carbon nanotube synthesis unit under conditions of decomposition of the reaction mixture (ferrocene in heptane) at a temperature of 800 °C at a carrier gas flow rate of 200 ml/min. The structure and geometric characteristics of the array’s carbon nanotubes were determined using scanning and transmission electron microscopy and Raman spectroscopy. The spectral coefficient of diffuse reflection (SDR) into the hemisphere in the wavelength range from 5,0 to 15,0 μm was determined. From the obtained experimental data, it was found that the emissivity (absorption coefficient) of an array of carbon nanotubes with a height of (230 – 250) μm is 0,98 – 0,99 in the spectral range from 5,0 to 13,7 μm and 0,975 – 0,995 in the range from 13,7 to 15,0 μm. Such a VOMWCNT array can be used to develop an absolutely black body with a high absorption coefficient and small mass and size characteristics, which is used for calibrating spacecraft’s infrared spectrometers.

Bifunctional single-atomic Mn sites for energy-efficient hydrogen production.

The electrocatalytic hydrogen evolution reaction (HER) for H2 production is essential for future renewable and clean energy technology. Screening energy-saving, low-cost, and highly active catalysts efficiently, however, is still a grand challenge due to the sluggish kinetics of the oxygen evolution reaction (OER) in electrolyzing water. Herein, we present a single atomic Mn site anchored on a boron nitrogen co-doped carbon nanotube array (Mn-SA/BNC), which is perfectly combined with the hydrazine electrooxidation reaction (HzOR) boosted water electrolysis concept. The obtained catalyst achieves 51 mV overpotential at the current density of -10 mA cm-2 for the cathodic HER and 132 mV versus the reversible hydrogen electrode for HzOR, respectively. Besides, in a two-electrode overall hydrazine splitting (OHzS) system, the Mn-SA/BNC catalyst only needs a cell voltage of only 0.41 V to output 10 mA cm-1, with strong durability and nearly 100% faradaic efficiency for H2 production. This work highlights a low-cost and high-efficiency energy-saving H2 production pathway.

Tunning of Optimal Parameters for Growth of Spinnable Carbon Nanotube Arrays at a Relatively Low Temperature and Pressure

Tunning of Optimal Parameters for Growth of Spinnable Carbon Nanotube Arrays at a Relatively Low Temperature and Pressure

Mathematical modelling of the electric field of carbon nanotube arrays used in cold cathode electron emission devices

Influence of the ratios of the carbon nanotube arrays geometrical parameters (height to radius – H/R, distance between the individual nanotube to height – S/H) on their properties to enhance the electric field strength at their tips and to accumulate electrostatic charge have been investigated. It was done with the help of their electric field mathematical modelling. Such modelling has shown that dependences of the emission current density on S/H ratio have maximums that are determined both by H/R and the applied electric field strength levels.

Dynamics of Carbon Nanotube Chains Residing on Flat Substrates

Stationary states of a single-walled carbon nanotube array lying on a flat substrate formed by the surface of a molecular crystal are investigated. Numerical modeling showed that in the case of weak interaction with the substrate it is more energetically favorable for nanotubes to get assembled into multilayer packing, while in the case of strong interaction (e.g., the interaction with the h–BN crystal surface) they form monolayer packing (i.e., a chain on the substrate surface). The dynamics of nanotube chains is modeled. We show that acoustic supersonic solitons can exist only in small-diameter nanotubes (D < 0.8 nm), and soliton motion is always accompanied by energy loss to excitation of internal vibrations in nanotubes. Low-amplitude vibrations are analyzed. For a finite nanotube chain residing on a flat substrate, it is shown that vibrations are confined to only the end nanotubes or a nanotube that forms a structural defect in the chain.

Modeling of the Growth Kinetics of Vertically Aligned Carbon Nanotube Arrays on Planar Substrates and an Algorithm for Calculating Rate Coefficients of This Process

Modeling of the Growth Kinetics of Vertically Aligned Carbon Nanotube Arrays on Planar Substrates and an Algorithm for Calculating Rate Coefficients of This Process

The importance for nanostructures in N-I-P ambiguously defined Si periodic concentrated solar devices

Arrays of periodic one-dimensional nano materials provide light–matter interaction in terms of tunable optical properties which are attractive for planning efficient optoelectronic devices. This paper is based on n-i-p thin-film amorphous silicon utilizes scaffolds of vertically aligned carbon nanotube (CNT) array for a fabrication of bottom-up grown Nano pillar (NP) array solar cells. The varying effect of the CNT extent over a wide range from 800 to 2000 nm on electrical properties of the solar cells and optical were examined. The NP solar cell with CNT extent over a range of 800 nm show ‘moth-eye’ broadband antireflection effort and the value 10% lower than an average reflectance. The enhanced optical absorption relocates to significant enhancements in quantum efficiency and photocurrent contrast to a conventional planar solar cell under low light circumstances. The open-circuit voltage (Voc) of the NP solar cell was established uniformly correlated with the illumination condition and CNT spacing. The main importance is to develop high efficiency one-dimensional nanostructured solar cells results were presented here.