Showing papers on "Nanotube published in 2013"
TL;DR: The fabrication and use of a hierarchical nanofluidic device made of a boron nitride nanotubes that pierces an ultrathin membrane and connects two fluid reservoirs is described, which allows the detailed study of fluidic transport through a single nanotube under diverse forces, including electric fields, pressure drops and chemical gradients.
Abstract: New models of fluid transport are expected to emerge from the confinement of liquids at the nanoscale1, 2, with potential applications in ultrafiltration, desalination and energy conversion3. Nevertheless, advancing our fundamental understanding of fluid transport on the smallest scales requires mass and ion dynamics to be ultimately characterized across an individual channel to avoid averaging over many pores. A major challenge for nanofluidics thus lies in building distinct and well-controlled nanochannels, amenable to the systematic exploration of their properties. Here we describe the fabrication and use of a hierarchical nanofluidic device made of a boron nitride nanotube that pierces an ultrathin membrane and connects two fluid reservoirs. Such a transmembrane geometry allows the detailed study of fluidic transport through a single nanotube under diverse forces, including electric fields, pressure drops and chemical gradients. Using this device, we discover very large, osmotically induced electric currents generated by salinity gradients, exceeding by two orders of magnitude their pressure-driven counterpart. We show that this result originates in the anomalously high surface charge carried by the nanotube's internal surface in water at large pH, which we independently quantify in conductance measurements. The nano-assembly route using nanostructures as building blocks opens the way to studying fluid, ionic and molecule transport on the nanoscale, and may lead to biomimetic functionalities. Our results furthermore suggest that boron nitride nanotubes could be used as membranes for osmotic power harvesting under salinity gradients.
906 citations
TL;DR: The high-performance electrochemical properties of graphene/carbon nanotube/graphene junctions at the interface of the differing carbon allotropic forms can provide more compact ac filtering units and discrete power sources in future electronic devices.
Abstract: In this research, 3-dimensional (3D) graphene/carbon nanotube carpets (G/CNTCs)-based microsupercapacitors (G/CNTCs-MCs) were fabricated in situ on nickel electrodes. The G/CNTCs-MCs show impedance phase angle of −81.5° at a frequency of 120 Hz, comparable to commercial aluminum electrolytic capacitors (AECs) for alternating current (ac) line filtering applications. In addition, G/CNTCs-MCs deliver a high volumetric energy density of 2.42 mWh/cm3 in the ionic liquid, more than 2 orders of magnitude higher than that of AECs. The ultrahigh rate capability of 400 V/s enables the microdevices to demonstrate a maximum power density of 115 W/cm3 in aqueous electrolyte. The high-performance electrochemical properties of G/CNTCs-MCs can provide more compact ac filtering units and discrete power sources in future electronic devices. These elevated electrical features are likely enabled by the seamless nanotube/graphene junctions at the interface of the differing carbon allotropic forms.
675 citations
TL;DR: Nanotubes and graphene have emerged as promising materials for use in ultrafast fiber lasers as discussed by the authors, and their unique electrical and optical properties enable them to be used as saturable absorbers that have fast responses and broadband operation and can be easily integrated in fibre lasers.
Abstract: Nanotubes and graphene have emerged as promising materials for use in ultrafast fibre lasers. Their unique electrical and optical properties enable them to be used as saturable absorbers that have fast responses and broadband operation and that can be easily integrated in fibre lasers.
673 citations
TL;DR: In the field of nanotube synthesis, catalytic chemical vapour deposition (CVD) is the prevailing synthesis method of carbon nanotubes as discussed by the authors, due to its higher degree of control and its scalability.
438 citations
IBM1
TL;DR: It is shown that aligned arrays of semiconducting carbon nanotubes can be assembled using the Langmuir-Schaefer method, and the intrinsic mobility of the nanotube is preserved after array assembly.
Abstract: Arrays of semiconducting single-walled carbon nanotubes with a nanotube density of more than 500 tubes per micrometre can be assembled using the Langmuir–Schaefer method and used to make transistors with significant device performance.
428 citations
TL;DR: In this paper, a detailed review of heat conduction research on both individual carbon nanotubes and nanostructured films consisting of arrays or disordered nanotube mats is presented.
Abstract: The extremely high thermal conductivities of carbon nanotubes have motivated a wealth of research. Progress includes innovative conduction metrology based on microfabricated platforms and scanning thermal probes as well as simulations exploring phonon dispersion and scattering using both transport theory and molecular dynamics. This article highlights these advancements as part of a detailed review of heat conduction research on both individual carbon nanotubes and nanostructured films consisting of arrays of nanotubes or disordered nanotube mats. Nanotube length, diameter, and chirality strongly influence the thermal conductivities of individual nanotubes and the transition from primarily diffusive to ballistic heat transport with decreasing temperature. A key experimental challenge, for both individual nanotubes and aligned films, is the separation of intrinsic and contact resistances. Molecular dynamics simulations have studied the impacts of specific types of imperfections on the nanotube conductance and its variation with length and chirality. While the properties of aligned films fall short of predictions based on individual nanotube data, improvements in surface engagement and postfabrication nanotube quality are promising for a variety of applications including mechanically compliant thermal contacts.
379 citations
TL;DR: The superior electrochemical performance of the GS-MWCNT@S composite is mainly attributed to the synergistic effects of GS and MWCNTs, which provide a 3D conductive network for electron transfer, open channels for ion diffusion, strong confinement of soluble polysulfides, and effective buffer for volume expansion of the S cathode during discharge.
Abstract: A multiwalled carbon nanotube/sulfur (MWCNT@S) composite with core–shell structure was successfully embedded into the interlay galleries of graphene sheets (GS) through a facile two-step assembly process. Scanning and transmission electron microscopy images reveal a 3D hierarchical sandwich-type architecture of the composite GS-MWCNT@S. The thickness of the S layer on the MWCNTs is ∼20 nm. Raman spectroscopy, X-ray diffraction, thermogravimetric analysis, and energy-dispersive X-ray analysis confirm that the sulfur in the composite is highly crystalline with a mass loading up to 70% of the composite. This composite is evaluated as a cathode material for Li/S batteries. The GS-MWCNT@S composite exhibits a high initial capacity of 1396 mAh/g at a current density of 0.2C (1C = 1672 mA/g), corresponding to 83% usage of the sulfur active material. Much improved cycling stability and rate capability are achieved for the GS-MWCNT@S composite cathode compared with the composite lacking GS or MWCNT. The superior e...
379 citations
TL;DR: Force sensing with nanotube resonators offers new opportunities for detecting and manipulating individual nuclear spins as well as for magnetometry measurements.
Abstract: A record force sensitivity at low temperatures is now reported using a carbon nanotube mechanical resonator.
370 citations
TL;DR: The significant brightening of nanotube photoluminescence is demonstrated through the creation of an optically allowed defect state that resides below the predicted energy level of the dark excitons.
Abstract: Semiconducting carbon nanotubes promise a broad range of potential applications in optoelectronics and imaging, but their photon-conversion efficiency is relatively low. Quantum theory suggests that nanotube photoluminescence is intrinsically inefficient because of low-lying 'dark' exciton states. Here we demonstrate the significant brightening of nanotube photoluminescence (up to 28-fold) through the creation of an optically allowed defect state that resides below the predicted energy level of the dark excitons. Emission from this new state generates a photoluminescence peak that is red-shifted by as much as 254 meV from the nanotube's original excitonic transition. We also found that the attachment of electron-withdrawing substituents to carbon nanotubes systematically drives this defect state further down the energy ladder. Our experiments show that the material's photoluminescence quantum yield increases exponentially as a function of the shifted emission energy. This work lays the foundation for chemical control of defect quantum states in low-dimensional carbon materials.
365 citations
TL;DR: Improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron delocalization between Pd d orbitals and PANI π-conjugated ligands and in electron transfer from Pd to PANI.
Abstract: Low cost, high activity, and long-term durability are the main requirements for commercializing fuel cell electrocatalysts. Despite tremendous efforts, developing non-Pt anode electrocatalysts with high activity and long-term durability at low cost remains a significant technical challenge. Here we report a new type of hybrid Pd/PANI/Pd sandwich-structured nanotube array (SNTA) to exploit shape effects and synergistic effects of Pd-PANI composites for the oxidation of small organic molecules for direct alcohol fuel cells. These synthesized Pd/PANI/Pd SNTAs exhibit significantly improved electrocatalytic activity and durability compared with Pd NTAs and commercial Pd/C catalysts. The unique SNTAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Besides the merits of nanotube arrays, the improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron...
343 citations
TL;DR: It can be concluded, at least for nanocomposites of TiO(2)-carbon (GR, CNT, and C(60)) obtained, that there is no much difference in essence on affecting the photocatalytic performance of semiconductor TiO (2) among these three different carbon allotropes.
Abstract: A series of TiO2–graphene (GR), −carbon nanotube (CNT), and −fullerene (C60) nanocomposite photocatalysts with different weight addition ratios of carbon contents are synthesized via a combination of sol–gel and hydrothermal methods. Their structures and properties are determined by the X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), transmission electron microscopy (TEM), nitrogen adsorption–desorption, and photoelectrochemical measurements. Photocatalytic selective oxidation of benzyl alcohol to benzaldehyde is employed as a model reaction to evaluate the photocatalytic activity of the TiO2–carbon (GR, CNT, and C60) nanocomposites under visible light irradiation. The results reveal that incorporating TiO2 with carbon materials can extend the adsorption edge of all the TiO2–carbon nanocomposites to the visible light region. For TiO2–GR, TiO2–CNT, and TiO2–C60 nanocomposites, the photocatalytic activities of the composites with optimum ratios, TiO2–0.1% GR, TiO2–0.5% CNT, and TiO2–1.0% ...
TL;DR: LiMn2O4 nanotube with a preferred orientation of (400) planes is prepared by using multiwall carbon nanotubes as a sacrificial template and shows a superfast second-level charge capability as a cathode for aqueous rechargeable lithium battery.
Abstract: LiMn2O4 nanotube with a preferred orientation of (400) planes is prepared by using multiwall carbon nanotubes as a sacrificial template. Because of the nanostructure and preferred orientation, it shows a superfast second-level charge capability as a cathode for aqueous rechargeable lithium battery. At the charging rate of 600C (6 s), 53.9% capacity could be obtained. Its reversible capacity can be 110 mAh/g, and it also presents excellent cycling behavior due to the porous tube structure to buffer the strain and stress from Jahn-Teller effects.
TL;DR: In this article, hierarchical functionalized multiwalled carbon nanotube (MWNT)/graphene structures with thicknesses up to tens of micrometers and relatively high density (> 1 g cm−3) are synthesized using vacuum filtration for the positive electrode of lithium batteries.
Abstract: Hierarchical functionalized multiwalled carbon nanotube (MWNT)/graphene structures with thicknesses up to tens of micrometers and relatively high density (>1 g cm−3) are synthesized using vacuum filtration for the positive electrode of lithium batteries. These electrodes, which are self-standing and free of binder and current collectors, utilize oxygen functional groups for Faradaic reactions in addition to double-layer charging, which can impart high gravimetric (230 Wh kg−1 at 2.6 kW kg−1) and volumetric (450 Wh L−1 at 5 kW L−1) performance. It is demonstrated that the gravimetric and volumetric capacity, capacitance, and energy density can be tuned by selective removal of oxygen species from as-prepared functionalized MWNT/graphene structures with heat treatments in H2/Ar, potentially opening new pathways for the design of electrodes with controlled surface chemistry.
TL;DR: In this paper, a sacrificial template method based on the Kirkendall effect was used to synthesize NiCo2S4 porous nanotubes, which showed a specific capacitance of 1093 F g−1 at a current density of 0.2 A g− 1.
Abstract: NiCo2S4 porous nanotubes are synthesised by a sacrificial template method based on the Kirkendall effect. The as-prepared NiCo2S4 nanotube electrode shows a specific capacitance of 1093 F g−1 at a current density of 0.2 A g−1 (933 F g−1 at 1 A g−1).
TL;DR: A general rule governing CNT behaviors in aqueous phase is revealed and an extremely simple way to achieve spatial separation of CNTs by their electronic structures is provided.
Abstract: The distribution of nanoparticles in different aqueous environments is a fundamental problem underlying a number of processes, ranging from biomedical applications of nanoparticles to their effects on the environment, health, and safety. Here, we study distribution of carbon nanotubes (CNTs) in two immiscible aqueous phases formed by the addition of polyethylene glycol (PEG) and dextran. This well-defined model system exhibits a strikingly robust phenomenon: CNTs spontaneously partition between the PEG- and the dextran-rich phases according to nanotube’s diameter and metallicity. Thermodynamic analysis suggests that this chirality-dependent partition is determined by nanotube’s intrinsic hydrophobicity and reveals two distinct regimes in hydrophobicity-chirality relation: a small diameter ( 1.2 nm) regime, where nanotube’s polarizability renders semiconducting tubes more hydro...
TL;DR: In this article, multi-walled carbon nanotube (MWCNT)/portland cement composites have been fabricated to evaluate their electromagnetic interference (EMI) shielding effectiveness (SE).
TL;DR: The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V( 2+)/V(3+) and VO(2+)/VO2(+) redox couples among the samples prepared at 500, 600, 700, and 800 °C.
Abstract: Carbon nanofiber/nanotube (CNF/CNT) composite catalysts grown on carbon felt (CF), prepared from a simple way involving the thermal decomposition of acetylene gas over Ni catalysts, are studied as electrode materials in a vanadium redox flow battery. The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V2+/V3+ and VO2+/VO2+ redox couples among the samples prepared at 500, 600, 700, and 800 °C. Moreover, this composite electrode in the full cell exhibits substantially improved discharge capacity and energy efficiency by ∼64% and by ∼25% at 40 mA·cm–2 and 100 mA·cm–2, respectively, compared to untreated CF electrode. This outstanding performance is due to the enhanced surface defect sites of exposed edge plane in CNF and a fast electron transfer rate of in-plane side wall of the CNT.
TL;DR: The suitable NT-Zn coatings with good intrinsic antibacterial properties can prevent post-operation infection and excellent osteogenesis inducing ability in the absence of extraneous osteogenic supplements is demonstrated and the ERK1/2 signaling is found to be involved.
TL;DR: An asymmetric supercapacitor (ASC) is fabricated using sGNS/cMWCNT/PANI and aGNS as the positive and negative electrodes, respectively and exhibits a superior long cycle life with 91% retention of the initial specific capacitance after 5000 cycles.
Abstract: Hierarchical sulfonated graphene nanosheet/carboxylated multiwalled carbon nanotube/polyaniline (sGNS/cMWCNT/PANI) nanocomposites were synthesized through an interfacial polymerization method. Activated porous graphene (aGNS) was prepared by combining chemical foaming, thermal reduction, and KOH activation. Furthermore, we have successfully fabricated an asymmetric supercapacitor (ASC) using sGNS/cMWCNT/PANI and aGNS as the positive and negative electrodes, respectively. Because of its unique structure, high capacitive performance, and complementary potential window, the ASC device can be cycled reversibly at a cell voltage of 1.6 V in a 1 M H2SO4 aqueous electrolyte, delivering a high energy density of 20.5 Wh kg–1 at a power density of 25 kW kg–1. Moreover, the ASC device also exhibits a superior long cycle life with 91% retention of the initial specific capacitance after 5000 cycles.
TL;DR: Mechanically excellent native cellulose nanofibers that are cleaved from plant cell walls have been modified by functionalized few-walled carbon nanotubes for hybrid nanofiber/nanotube aerogels allowing responsive conductivity and pressure sensing.
Abstract: Mechanically excellent native cellulose nanofibers that are cleaved from plant cell walls have been modified by functionalized few-walled carbon nanotubes for hybrid nanofiber/nanotube aerogels. They show elastic mechanical behavior in combination with reversible electrical response under compression allowing responsive conductivity and pressure sensing. The concept combines wide availability of nanocellulosics and electrical functionality of carbon nanotubes synergistically.
TL;DR: In this paper, self-organized amorphous TiO 2 nanotube arrays (NTAs) were successfully fabricated on both Ti foil and porous Ti foam through electrochemical anodization techniques.
TL;DR: A rapid, efficient, and green approach to the fabrication of highly active catalysts by coating Pd nanoparticles (NPs) on reduced graphene oxide (rGO)-carbon nanotube (CNT) nanocomposite is reported.
Abstract: Facile and Green Synthesis of Palladium Nanoparticles-Graphene-Carbon Nanotube Material with High Catalytic Activity
TL;DR: This preparation of MnO2 nanotubes functionalized with Co3O4 nanoparticles and their use as bifunctional air cathode catalysts for oxygen reduction reaction and oxygen evolution reaction in rechargeable zinc-air batteries exhibit enhanced catalytic reactivity toward oxygen evolution Reaction under alkaline conditions.
Abstract: We report the preparation of MnO2 nanotubes functionalized with Co3O4 nanoparticles and their use as bifunctional air cathode catalysts for oxygen reduction reaction and oxygen evolution reaction in rechargeable zinc-air batteries. These hybrid MnO2/Co3O4 nanomaterials exhibit enhanced catalytic reactivity toward oxygen evolution reaction under alkaline conditions compared with that in the presence of MnO2 nanotubes or Co3O4 nanoparticles alone.
TL;DR: In this article, the resistivity response under cyclic loading of thermoplastic polyurethane (TPU) multi-walled carbon nanotube (MWNT) elastomeric nanocomposite films fabricated by a solution process with a low percolation threshold is reported.
TL;DR: The metal-graphene-CNT structure is used to directly fabricate field-emitter devices and double-layer capacitors, and can stimulate the development of several energy-efficient technologies.
Abstract: Graphene was grown directly on porous nickel films, followed by the growth of controlled lengths of vertical carbon nanotube (CNT) forests that seamlessly emanate from the graphene surface. The metal–graphene–CNT structure is used to directly fabricate field-emitter devices and double-layer capacitors. The three-dimensional nanostructured hybrid materials, with better interfacial contacts and volume utilization, can stimulate the development of several energy-efficient technologies.
Journal Article•
TL;DR: The data exclusively indicate that twisted ribbons are the precursors for coiled ribbons, and the latter structures give rise to nanotubes, and it is shown chirality is a key requirement for nanotube formation.
TL;DR: In this paper, the effects of varying the MWCNT content, as well as the additional use of drawing and poling on the polymorphic behavior and electroactive (piezoelectric) properties of the membranes obtained.
Abstract: We prepared poly(vinylidene fluoride) (PVDF)/multiwalled carbon nanotube (MWCNT) nanocomposites using the electrospinning process and investigated the effects of varying the MWCNT content, as well as the additional use of drawing and poling on the polymorphic behavior and electroactive (piezoelectric) properties of the membranes obtained. Fourier transform infrared spectroscopy and wide-angle X-ray diffraction revealed that dramatic changes occurred in the β-phase crystal formation with the MWCNT loading. This was attributed to the nucleation effects of the MWCNTs as well as the intense stretching of the PVDF jets in the electrospinning process. The remanent polarization and piezoelectric response increased with the amount of MWCNTs and piezoelectric β-phase crystals. A further mechanical stretching and electric poling process induced not only highly oriented β-phase crystallites, but also very good ferroelectric and piezoelectric performances. In the drawn samples, the interfacial interaction between the...
TL;DR: In this paper, a hybrid material consisting of magnetite (Fe3O4) nanocrystals grown on multi-walled carbon nanotube (MWCNT) was used as a high-performance microwave absorber in the 2-18 GHz band.
Abstract: The understanding of the interaction between the building blocks in the hybrids can advance our comprehension of design principles in high-performance microwave absorbing materials. Here, we report a hybrid material consisting of magnetite (Fe3O4) nanocrystals grown on multiwalled carbon nanotube (MWCNT) as a high-performance microwave absorber in the 2–18 GHz band, although Fe3O4 nanocrystals or MWCNTs alone or their physical mixture show little microwave absorption. The hybrid is characterized by transmission electron microscopy, X-ray diffraction, and vector network analysis, X-ray absorption near-edge structures at the C K-edge and Fe L3,2-edge, and electron spin resonance analysis. Microstructural analysis reveals that Fe3O4 nanocrystals are immobilized on the MWCNT surface by a strong interaction. Charges in the MWCNT/Fe3O4 hybrids transfer from the conduction band in Fe3O4 to C 2p-derived states in the MWCNT substrate. Dipole interaction between the magnetic nanocrystals is increased. The synergeti...
TL;DR: A novel route via microwave irradiation is reported to synthesize a bio-inspired hierarchical graphene--nanotube--iron three-dimensional nanostructure as an anode material in lithium-ion batteries enabling Li-ions to have greater access to the electrode material.
Abstract: In this study, we report a novel route via microwave irradiation to synthesize a bio-inspired hierarchical graphene–nanotube–iron three-dimensional nanostructure as an anode material in lithium-ion batteries. The nanostructure comprises vertically aligned carbon nanotubes grown directly on graphene sheets along with shorter branches of carbon nanotubes stemming out from both the graphene sheets and the vertically aligned carbon nanotubes. This bio-inspired hierarchical structure provides a three-dimensional conductive network for efficient charge-transfer and prevents the agglomeration and restacking of the graphene sheets enabling Li-ions to have greater access to the electrode material. In addition, functional iron-oxide nanoparticles decorated within the three-dimensional hierarchical structure provides outstanding lithium storage characteristics, resulting in very high specific capacities. The anode material delivers a reversible capacity of ∼1024 mA·h·g–1 even after prolonged cycling along with a Cou...
TL;DR: Interestingly, the NixCo2x(OH)6x/TiN NTA electrode outperforms the NiCo2O4/Ti ntube array electrode, indicating that this self-standing Nix co2x (OH) 6x/ TiN Nta monolith is a promising candidate for high-performance supercapacitor applications.
Abstract: NixCo2x(OH)(6x), as a precursor of intensively studied NiCo2O4, has been directly deposited into self-standing titanium nitride nanotube array (TiN NTA) grid monolithic supports to form a coaxial nanostructured electrode for supercapacitors. With TIN NTA substrates providing a large surface area, fast electron transport, and enhanced structure stability, this NixCo2x(OH)(6x)/TiN electrode exhibits superior pseudocapacitive performance with a high specific capacitance of 2543 F g(-1) at 5 mV s(-1), remarkable rate performance of 660 F g(-1) even at 500 mV s(-1), and promising cycle performance (about 6.25% capacitance loss for 5000 cycles). Interestingly, the NixCo2x(OH)(6x)/TiN NTA electrode outperforms the NiCo2O4/TiN NTA electrode, indicating that this self-standing NixCo2x(OH)(6x)/TiN NTA monolith is a promising candidate for high-performance supercapacitor applications.