One-dimensional Carbon Nanotubes Research Articles

Ti3C2MXenes modified with in situ grown carbon nanotubes for enhanced electromagnetic wave absorption properties

Ti3C2TxMXenes modified within situgrown carbon nanotubes (CNTs) are fabricatedviaa simple catalytic chemical vapor deposition (CVD) process.

A chemical approach to perovskite solar cells: control of electron-transporting mesoporous TiO2 and utilization of nanocarbon materials.

Over the past several years, organometal halide perovskite solar cells (PSCs) have attracted considerable interest from the scientific research community because of their potential as promising photovoltaic devices for use in renewable energy production. To date, high power conversion efficiencies (PCEs) of more than 20% have been primarily achieved with mesoscopic-structured PSCs, where a mesoporous TiO2 (mTiO2) layer is incorporated as an electron-transporting mesoporous scaffold into the perovskite crystal, in addition to a compact TiO2 (cTiO2) as an electron-transporting layer (ETL). In this Perspective, we first summarize recent research on the preparation strategies of the mTiO2 layer with a high electron transport capability by facile sol-gel methods instead of the conventional nanoparticle approach. The importance of the control of the pore size and grain boundaries of the mTiO2 in achieving high PCEs for PSCs is discussed. In addition, an alternative method to improve the electron transport in the mTiO2 layer via the incorporation of highly conductive nanocarbon materials, such as two-dimensional (2D) graphene and one-dimensional (1D) carbon nanotubes, is also summarized. Finally, we highlight the utilization of zero-dimensional (0D) nanocarbon, i.e., fullerenes, as an n-type semiconducting material in mesostructure-free planar PSCs, which avoids high-temperature sintering during the fabrication of an ETL.

The effect of filler dimensionality on the electromechanical performance of polydimethylsiloxane based conductive nanocomposites for flexible strain sensors

Flexible and wearable strain sensors based on conductive polymer composites (CPCs) for human motion detection have been highlighted recently. Herein, two flexible conductive composites were fabricated by mixing matrix polydimethylsiloxane (PDMS) with zero-dimensional conductive filler carbon black (CB) and one-dimensional carbon nanotubes (CNTs), respectively. A low percolation threshold of CB/PDMS (0.48 vol%) was achieved, while this value was higher than that of CNTs/PDMS (0.13 vol%). In strain-dependent response tests, compared with CNTs/PDMS with a gauge factor (GF) of 4.36 (a strain of 10%), CB/PDMS composites showed a higher sensitivity with a larger GF of 15.75 (a strain of 10%). A good reproducibility was obtained in stretching-releasing process for the two composites. In long-term cyclic test, CB/PDMS showed more stable sensing behaviors, while a slight drifting and fluctuation was observed for CNTs/PDMS. Generally, two composites both possessed satisfactory durability. Mathematical models were proposed to explain the mechanism of the distinct strain sensing behaviors. A smart glove was assembled to monitor the finger motion to evaluate the application of the two composites as flexible strain sensors.

Nanoarchitecture Based SERS for Biomolecular Fingerprinting and Label-Free Disease Markers Diagnosis.

ConspectusSurface-enhanced Raman spectroscopy (SERS) fingerprinting is highly promising for identifying disease markers from complex mixtures of clinical sample, which has the capability to take medical diagnoses to the next level. Although vibrational frequency in Raman spectra is unique for each biomolecule, which can be used as fingerprint identification, it has not been considered to be used routinely for biosensing due to the fact that the Raman signal is very weak. Contemporary SERS has been demonstrated to be an excellent analytical tool for practical label-free sensing applications due its ability to enhance Raman signals by factors of up to 108–1014 orders of magnitude. Although SERS was discovered more than 40 years ago, its applications are still rare outside the spectroscopy community and it is mainly due to the fact that how to control, manipulate and amplify light on the “hot spots” near the metal surface is in the infancy stage.In this Account, we describe our contribution to develop nanoachitecture based highly reproducible and ultrasensitive detection capability SERS platform via low-cost synthetic routes. Using one-dimensional (1D) carbon nanotube (CNT), two-dimensional (2D) graphene oxide (GO), and zero-dimensional (0D) plasmonic nanoparticle, 0D to 3D SERS substrates have been designed, which represent highly powerful platform for biological diagnosis. We discuss the major design criteria we have used to develop robust SERS substrate to possess high density “hot spots” with very good reproducibility. SERS enhancement factor for 3D SERS substrate is about 5 orders of magnitude higher than only plasmonic nanoparticle and more than 9 orders of magnitude higher than 2D GO. Theoretical finite-difference time-domain (FDTD) stimulation data show that the electric field enhancement |E|2 can be more than 2 orders of magnitude in “hot spots”, which suggests that SERS enhancement factors can be greater than 104 due to the formation of high density “hot spots” in 3D substrate. Next, we discuss the utilization of nanoachitecture based SERS substrate for ultrasensitive and selective diagnosis of infectious disease organisms such as drug resistance bacteria and mosquito-borne flavi-viruses that cause significant health problems worldwide. SERS based “whole-organism fingerprints” has been used to identify infectious disease organisms even when they are so closely related that they are difficult to distinguish. The detection capability can be as low as 10 CFU/mL for methicillin-resistant Staphylococcus aureus (MRSA) and 10 PFU/mL for Dengue virus (DENV) and West Nile virus (WNV). After that, we introduce exciting research findings by our group on the applications of nanoachitecture based SERS substrate for the capture and fingerprint detection of rotavirus from water and Alzheimer’s disease biomarkers from whole blood sample. The SERS detection limit for β-amyloid (Aβ proteins) and tau protein using 3D SERS platform is several orders of magnitude higher than the currently used technology in clinics. Finally, we highlight the promises, major challenges and prospect of nanoachitecture based SERS in biomedical diagnosis field.

Synergistic effects of 2D graphene oxide nanosheets and 1D carbon nanotubes in the constructed 3D carbon aerogel for high performance pollutant removal

To create interspace-enlarged and sites-exposed graphene-based adsorbents for pollutant management, three-dimensional macrostructures (3D GTs) were facilely constructed via self-assembly of two-dimensional graphene oxide nanosheets (2D GO) and one-dimensional carbon nanotubes (1D CNTs). Since the existence of CNTs acting like frames may reinforce the mechanical strength of the GO nanosheets, the density of the stable and porous 3D GTs was reduced to 0.2mg/mL which was much lower than the minimum concentration required to form pure GO 3D macrostructures. The 3D GTs exhibited superior adsorption capabilities to emerging pollutants such as oxytetracycline (1729mg/g) and diethyl phthalate (680mg/g), and traditional pollutants such as methylene blue (685mg/g), Cd2+ (235mg/g) and diesel (421g/g). The adsorption capacity of 3D GTs is higher than the reported graphene/GO and CNTs-based adsorbents, which can be attributed to the synergistic effects of GO and CNTs in micro-environment, nano-substrate, and active sites. Firstly, the assembled GO sheets were highly separated and in monolayer form, which created large interspaces in 3D GTs. Secondly, GO and CNTs provided abundant adsorption sites. Thirdly, the micro environment of interspaces in stable 3D GTs could be tuned to achieve selective adsorption to particular pollutant. In short, we propose a super graphene-based adsorbent which is competitive and scalable for water purification.

Van-der-Waals-gap tunneling spectroscopy for single-wall carbon nanotubes

As a consequence of their unique electronic band structures, low-dimensional materials such as one-dimensional (1D) single-wall carbon nanotubes (SWCNTs), 2D graphene and various 2D transition-metal dichalcogenides have exhibited intriguing electrical transport properties when incorporated into field-effect transistors. Meanwhile, the van-der-Waals (vdW) interfaces between top-contacted metals and low-dimensional materials have become a challenging issue for future high-performance electronics. Here, we report a new aspect of vdW interface that offers vdW-gap tunneling spectroscopy by adopting indium (In) as a top-contacted metal on SWCNTs without an artificial insulating tunnel barrier. We show that multiple differential conductance peaks for varying bias voltages correspond to the van Hove singularities existing in the electronic density of states of SWCNTs. Our first-principles calculations reveal that In forms a physisorption interface with a considerable vdW gap, which causes little disruption to the density of states of the SWCNTs near the metal interface and which thus allows vdW-gap tunneling spectroscopy.

Constructing Two-, Zero-, and One-Dimensional Integrated Nanostructures: an Effective Strategy for High Microwave Absorption Performance.

A novel "201" nanostructure composite consisting of two-dimensional MoS2 nanosheets, zero-dimensional Ni nanoparticles and one-dimensional carbon nanotubes (CNTs) was prepared successfully by a two-step method: Ni nanopaticles were deposited onto the surface of few-layer MoS2 nanosheets by a wet chemical method, followed by chemical vapor deposition growth of CNTs through the catalysis of Ni nanoparticles. The as-prepared 201-MoS2-Ni-CNTs composites exhibit remarkably enhanced microwave absorption performance compared to Ni-MoS2 or Ni-CNTs. The minimum reflection loss (RL) value of 201-MoS2-Ni-CNTs/wax composites with filler loading ratio of 30 wt % reached -50.08 dB at the thickness of 2.4 mm. The maximum effective microwave absorption bandwidth (RL< -10 dB) of 6.04 GHz was obtained at the thickness of 2.1 mm. The excellent absorption ability originates from appropriate impedance matching ratio, strong dielectric loss and large surface area, which are attributed to the "201" nanostructure. In addition, this method could be extended to other low-dimensional materials, proving to be an efficient and promising strategy for high microwave absorption performance.

Melt Compounding of Thermoplastic Polyurethanes Incorporating 1D and 2D Carbon Nanofillers

ABSTRACTThermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic properties.

A three-dimensional absorber hybrid with polar oxygen functional groups of MWNTs/graphene with enhanced microwave absorbing properties

Abstract A three-dimensional absorber hybrid with polar oxygen-containing functional groups was fabricated by the incorporation of two-dimensional reduced graphene oxide (rGO) with one-dimensional multi-walled carbon nanotubes (MWNTs) via ultrasonication filtration method. The aim of the work is to investigate the effectiveness of three-dimensional absorber hybrid with polar oxygen-containing functional groups on the enhanced microwave absorbing properties. As a contrast, the three-dimensional absorber hybrid of Graphene nanoplatelets (GNPs) and MWNTs were also fabricated by the same method. The structure and morphology of the GNPs(rGO)/MWNTs hybrids were characterized by scanning electron microscopy (SEM), trans-mission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. SEM and TEM results indicated that the three-dimensional architecture of GNPs(rGO)/MWNTs was fabricated, and the dispersion of GNPs(and/or rGO) was promoted due to the bridge construct of MWNTs between GNPs. The polarization differences between GNPs/MWNTs and rGO/MWNTs were investigated by the Cole-Cole semicircle model. The microwave absorbing results revealed that the rGO/MWNTs hybrids exhibited a −41 dB reflection loss in the frequency at 9.6 GHz with a bandwidth of 0.8 GHz (9.2 GHz–10 GHz) below −20 dB, which was higher than that of the GNPs/MWNTs hybrids (−23 dB at 8.4 GHz, 0.2 GHz bandwidth below −20 dB). This investigation indicated that the three-dimensional with polar oxygen-containing functional groups was beneficial to enhancing microwave absorbing properties.

Novel template preparation of carbon nanotubes with natural HNTs employing selective PVA modification

Abstract A novel approach to prepare one-dimensional carbon nanotubes by using halloysite nanotubes (HNTs) as the template while employing selective polyvinyl alcohol (PVA) modification as the carbon source was developed. A series of characterizations (thereof including XRD, FT-IR, SEM, TEM, BET, Raman, XPS and SAED) was used to study the formation process of carbon nanotubes. The characterizations could distinctly demonstrate the surface of HNTs modified by PVA molecular. The XRD, Raman, SEM, TEM, SEAD and XPS characterizations indicated that the template-obtained products were of CNTs structure and a high specific surface area of 381.5 m 2 /g.

Highly effective energy dissipation system based on one-dimensionally arrayed short single-walled carbon nanotubes

In this paper, the impact energy dissipation characteristics of one-dimensional (1D) short single-walled carbon nanotube (SWNT) system are investigated via molecular dynamics (MD) simulation. It is found that 1D SWNT system has good force mitigation performance and extraordinarily high specific energy absorption (SEA) upon high-speed impact in the absence of plasticity, which is 1 to 2 orders advantageous over macroscale impact protection devices and structures. Moreover, a simple model based on the theorem of momentum can give an accurate prediction of force mitigation effect. The mechanism of this non-plastic impact energy dissipation lies in the transformation of impact energy to the kinetic and potential energy of SWNT molecules. Similar to macroscopic metallic rings, SWNTs can buckle under large force, which in fact enhances force mitigation capability of the system. A continuum model is established, able to predict the critical forces of SWNTs of different radii. Finally, system performance upon impact speeds in a broader range and the influence of parameters such as system length and SWNT radius are discussed. This work may be instructive to the design of novel impact energy mitigation system at nanoscale.

Three-Dimensional CNT/Graphene–Li2S Aerogel as Freestanding Cathode for High-Performance Li–S Batteries

Three-dimensional (3D) CNT/graphene-Li2S (3DCG–Li2S) cathodes with 81.4 wt % record Li2S loading have been realized through solvothermal reaction and a subsequent liquid-infiltration-evaporation coating method. The highly flexible, conductive 3D mesoporous interconnected network based on two-dimensional (2D) graphene nanosheets and one-dimensional (1D) carbon nanotubes (CNTs) provides highly efficient channels for electron transfer and ionic diffusion, and leads to a low solubility of polysulfides in electrolytes in charges/discharges. Without polymeric binders or conductive additives, the freestanding 3DCG–Li2S cathode exhibits record electrochemical performances including reversible discharge capacities of 1123.6 mAh g–1 and 914.6 mAh g–1, 0.02% long-term capacity decay per cycle and a high-rate capacity of 514 mAh g–1 at 4 C. The reported 3DCG–Li2S aerogel with ultrahigh Li2S content presents promising application potentials in high-performance Li–S batteries.

Three-dimensional vertically aligned hybrid nanoarchitecture of two-dimensional molybdenum disulfide nanosheets anchored on directly grown one-dimensional carbon nanotubes for use as a counter electrode in dye-sensitized solar cells

Two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets were synthesized to anchor onto the surfaces of directly grown one-dimensional (1D) carbon nanotubes (CNTs) on fluorinated tin oxide (FTO) glass. This three-dimensional (3D) vertically aligned hybrid nanoarchitecture was used in Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The prepared 2D MoS2 nanosheets, with exposed layers, provided a great deal of edge-plane catalytically active sites for I3− reduction. The directly grown 1D CNTs provide an attractive template that offers a large surface area to promote the loading of 2D MoS2 nanosheets for enhancing electrochemical activity. The CNTs directly grown on the FTO substrate provided a high-speed pathway that promoted charge transport and transfer, resulting in a lower electron lifetime that increased the exchange current density and reduced the charge-transfer resistance. The DSSCs assembled with the 3D vertically aligned MoS2/CNT hybrid nanoarchitecture CE achieved a power conversion efficiency of 7.83%, 9.5% higher than that of a cell prepared with a Pt film CE (7.15%).

Graphitic carbon nitride nanosheets modified multi-walled carbon nanotubes as 3D high efficient sensor for simultaneous determination of dopamine, uric acid and tryptophan

Graphitic carbon nitride (g-C3N4) nanosheets, as graphene-like ultrathin semiconductor material, have strong covalent bonds between carbon and nitride atoms. The nitrogen atoms doping in the carbon architecture that greatly enhancing electrical properties and accelerating the electrontransfer rate, which can improve the electrical properties of g-C3N4 nanosheets. Herein, a novel electrochemical sensor was developed by immobilizing a three-dimensional (3D) hybrid nanocomposite which consisted of one-dimensional (1D) multi-walled carbon nanotubes (MWNTs) and two-dimensional (2D) g-C3N4 nanosheets on a glassy carbon electrode (g-C3N4/MWNTs/GCE). The g-C3N4/MWNTs/GCE exhibited excellent response toward the oxidation reactions of dopamine (DA), uric acid (UA) and tryptophan (Trp). Under the optimum conditions, the electrochemical sensor was used in the detection of DA, UA and Trp, and achieved wide ranges of 2.0–43.5μM, 5.0–189.0μM and 65.0–1815.0μM with low detection limits (S/N=3) of 5.0×10−8M, 5.0×10−7M and 1.0×10−6M, respectively. In addition, the coexistence of ascorbic acid (AA) has no obvious interference toward the detection of DA, UA and Trp. Thus, the modified electrodes were successfully applied for the determination of DA, UA and Trp in urine and serum samples using the standard adding method with satisfactory results.

Rheological and conductivity percolations of syndiotactic polystyrene composites filled with graphene nanosheets and carbon nanotubes: A comparative study

Two-dimensional graphene nanosheets (GNSs) and one-dimensional carbon nanotubes (CNTs) possess large aspect ratios but different geometries. In this study, syndiotactic polystyrene (sPS) composites reinforced with different contents of GNSs were prepared via a solution coagulation method. The dispersion and microstructure of GNSs in sPS were confirmed via transmission electron microscopy and atomic force microscopy. Rheological and electrical properties of sPS/GNS composites were investigated to reveal the effect of filler concentration, and the results were compared with those of sPS/CNT composites. Percolation scaling laws were applied to the magnitudes of storage modulus and electrical conductivity to determine the threshold concentration and corresponding exponent. The sPS/GNS and sPS/CNT composites possess a similar percolation threshold for melt elasticity and solid conductivity. However, the rheological threshold (∼0.1 vol%) is distinctly lower than the conductivity threshold (∼0.5 vol%) because of the formation of polymer–nanofiller hybrid network. The exponents for rheological and electrical percolations of sPS/GNS composites are determined as 4.12 and 4.71, respectively, which are higher than the corresponding values of 2.64 and 2.87 for sPS/CNT composites. The derived exponents indicate that the 2D GNS-related network is more effective than the 1D CNT-related network for enhancing the melt elasticity and solid conductivity of sPS matrix.

A nano-sandwich construct built with graphene nanosheets and carbon nanotubes enhances mechanical properties of hydroxyapatite&amp;ndash;polyetheretherketone scaffolds

A nano-sandwich construct was built by combining two-dimensional graphene nanosheets (GNSs) and one-dimensional carbon nanotubes (CNTs) to improve the mechanical properties of hydroxyapatite–polyetheretherketone (HAP–PEEK) scaffolds for bone tissue engineering. In this nano-sandwich construct, the long tubular CNTs penetrated the interlayers of graphene and prevented their aggregation, increasing the effective contact area between the construct and matrix. The combination of GNSs and CNTs in a weight ratio of 2:8 facilitated the dispersion of each other and provided a synergetic effect in enhancing the mechanical properties. The compressive strength and modulus of the scaffolds were increased by 63.58% and 56.54% at this time compared with those of HAP–PEEK scaffolds, respectively. The carbon-based fillers, pulling out and bridging, were also clearly observed in the matrix. Moreover, the dangling of CNTs and their entangling with GNSs further reinforced the mechanical properties. Furthermore, apatite layer formed on the scaffold surface after immersing in simulated body fluid, and the cells attached and spread well on the surface of the scaffolds and displayed good viability, proliferation, and differentiation. These evidence indicate that the HAP–PEEK scaffolds enhanced by GNSs and CNTs are a promising alternative for bone tissue engineering.

Liquid crystal behavior induced assembling fabrication of conductive chiral MWCNTs@NCC nanopaper

The conductive chiral MWCNTs@NCC nanopapers obtained by the assembly of nanocrystalline cellulose liquid crystals (NCC LCs) host matrix along with one-dimensional (1-D) multi-walled carbon nanotubes (MWCNTs) have been studied in this work. Circular dichroism (CD) studies show strong signals stemming from the chiral nematic structure. Notably, the introduction of the MWCNTs has a pronounced effect on the chiral structure of the as-prepared nanopaper. Our experimental results indicate the multiple weak molecular interactions existing between MWCNTs and NCC are responsible for the effective dispersion and stabilization of MWCNTs. Moreover it also confirms the resulting nanopaper has an increased conductivity of 4.2S/m at 1.96wt% MWCNTs. So the co-assembly of the nanocomposite herein opens a gateway for preparing functional materials combining the photonic properties of the NCC LCs matrix with other building blocks that can supply other advantageous functions.

Ton-scale metal–carbon nanotube composite: The mechanism of strengthening while retaining tensile ductility

One-dimensional carbon nanotubes (CNT), which are mechanically strong and flexible, enhance strength of the host metal matrix. However, the reduction of ductility is often a serious drawback. Here, we report significantly enhanced plastic flow strength, while preventing tensile ductility reduction, by uniformly dispersing CNTs in Al matrix. Nanoscale plasticity and rupturing processes near CNTs were observed by in-situ mechanical tests inside Transmission Electron Microscope (TEM). CNTs act like forest dislocations and have comparable density (∼1014/m2), and such 1D nano-dispersion hardening is studied in detail by in situ TEM and molecular dynamics simulations. Rupture-front blunting and branching are seen with in situ TEM, which corroborates the result from macro-scale tension tests that our Al+CNT nanocomposite is quite damage- and fault-tolerant. We propose a modified shear-lag model called “Taylor-dispersion” hardening model to highlight the dual roles of CNTs as load-bearing fillers and “forest dislocations” equivalent that harden the metal matrix, for the plastic strength of metal+CNT nanocomposite.

Electrical Current Oscillations in Lower-Dimensional Battery Electrodes

In order to enhance the capacity of a charge storage device, nanostructures such as one-dimensional (1-D) carbon nanotubes (CNTs) have often been employed, much of the time with the effect of increasing the surface area exposed to electrolyte or enhancing the electrode inter-connections and reducing the electrical resistance. Previous work also demonstrated the need for new physics based on lower dimensional density of states (DoS), as would occur in CNTs or graphene [1]. Here, for nanostructured battery electrodes, we propose a new current-voltage (I-V) model based on 2D and 1D DoS, and compare with related experiments. The model is broadly based on Marcus-Hush-Chidsey (MHC) kinetics and is aimed to extend the utility of the MHC formulations, to a larger class of materials and situations. We employ an integral expression for current, which involves the DoS, the Fermi-Dirac function, and the Arrhenius rate law as the basis. Our model provides better agreement to measured chronopotentiometry data on Li-ion batteries with nanostructured organic polymer electrodes, compared to previous analysis. An interesting feature of our model is the prediction in one-dimensional nanostructures of electrical current oscillations in the I-V curve, corresponding to the gradual population (and de-population) of each successive sub-band, provided that the sub-band widths are comparable to the reorganization energy. We posit that the consideration of a variable/non-constant DOS in MHC electrokinetics may yield tests of dimensional character and concomitant contribution to electrochemical systems. [1] H. Yamada and P. R. Bandaru, Appl. Phys. Lett. 102, 173113 (2013), ibid 104, 213901 (2014).

Complementary Metal-Oxide-Semiconductor Integrated Carbon Nanotube Arrays: Toward Wide-Bandwidth Single-Molecule Sensing Systems.

There is strong interest in realizing genomic molecular diagnostic platforms that are label-free, electronic, and single-molecule. One attractive transducer for such efforts is the single-molecule field-effect transistor (smFET), capable of detecting a single electronic charge and realized with a point-functionalized exposed-gate one-dimensional carbon nanotube field-effect device. In this work, smFETs are integrated directly onto a custom complementary metal-oxide-semiconductor chip, which results in an array of up to 6000 devices delivering a measurement bandwidth of 1 MHz. In a first exploitation of these high-bandwidth measurement capabilities, point functionalization through electrochemical oxidation of the devices is observed with microsecond temporal resolution, which reveals complex reaction pathways with resolvable scattering signatures. High-rate random telegraph noise is detected in certain oxidized devices, further illustrating the measurement capabilities of the platform.