Carbon Nanotube Heterostructures Research Articles

NiCoP based carbon nanotube heterostructure for improved oxygen redox reaction kinetics in Li-O2 batteries

The design of ultra-stable cathode materials of Li-O2 batteries with excellent catalytic performance is very important and desirable. However, some problems such as sluggish electrochemical reaction kinetics and unwanted side reactions still remain challenging. Carbon materials own hierarchical porous structure which facilitates mass transport and accommodates discharge products but are not stable enough as cathode of Li-O2 batteries. Here in, we fabricated a unique NiCo bimetallic phosphide combined with carbon nanotube heterostructure (abbreviated as NiCoP/CNT) by hydrothermal method. Density functional theory (abbreviated as DFT) calculation demonstrates that bimetallic phosphide NiCoP/CNT delivered much better electrical conductivity, greater adsorption to reactants, and more electron transfer with discharge products Li2O2, compared to monometallic phosphides CoP and Ni2P. Therefore, NiCoP/CNT based cathode displayed low overpotential of 0.87 V at current of 100 mA g−1 with a fixed specific capacity of 1000 mAh g−1 and run steadily over 150 cycles under high current of 500 mA g−1 with a fixed specific capacity of 1000 mAh g−1. Furthermore, Ex-situ X-ray Photoelectron Spectroscopy and in-situ differential electrochemical mass spectroscopy proved the existence of intermediate products Li2-xO2. This approach provides a reference for designing and synthesis of bimetallic cathode in Li-O2 batteries.

Filled carbon-nanotube heterostructures: from synthesis to application

Microstructures is an international peer-reviewed, open access, online journal. The journal of Microstructures publishes articles covering new research and developments, perspectives, and reviews related to the microstructures of materials, including, but not limited to metals and alloys, ceramics, polymers, composites, crystals, glasses, biomaterials, interfaces and nanomaterials.

One-pot hydrothermal growth of indium oxide-CNT heterostructure via single walled carbon nanotube scaffolds and their application toward flexible NO2 gas sensors

Single walled carbon nanotubes (SWNTs) are recognized as a promising sensing material for flexible NO2 gas sensors, whereas poor recovery at room temperature is a significant barrier to practical application. This study reports a one-pot hydrothermal synthesis of an indium oxide/single-walled carbon nanotube heterostructure (h-In2O3/SWNT) for efficient recovery in gas sensors. This results in the stable formation of 2-dimensional electron gases and their favorable electron compensation in the channel layers. The h-In2O3/SWNT FET gas sensors (h-GS) exhibit a sensing resolution of 1 ppm, negligible degradation over 9 consecutive cycled exposures with a 2-day-interval, and a significant improvement in recovery within 10 min at room temperature. Surprisingly, even when the flexible h-GS is evaluated under repeated tensile strain of 0.88 %, electrical reliability and reproducibility of the h-GS is fully validated. Thus, with its demonstrated robust sensing properties and compensation scheme, the h-In2O3/SWNT is expected to be a promising candidate for use as a novel sensing layer in a wearable gas sensor, resolving one of the long-standing issues associated with gas sensor sluggish recovery and reliability for impact.

MoS2 quantum dots and titanium carbide co-modified carbon nanotube heterostructure as electrode for highly sensitive detection of zearalenone.

Anovel electrochemical sensor has been fabricated for sensitive determination of zearalenone (ZEA) in food samples based on molybdenum disulfide quantum dots (MoS2 QDs) and two-dimensional titanium carbide (2D-Ti3C2Tx MXene) co-modified multi-walled carbon nanotube (MWCNT) heterostructure. Physical and electrochemical characterizations reveal that 2D-Ti3C2Tx and MoS2 QDs co-modified MWCNTs yields synergistic signal amplification effect, together with large specific surface area and excellent conductivity for the heterostructure, endowing the developed sensor with high detection performance to ZEA. Under optimized conditions, the sensor shows a wide linear range from 3.00 to 300ngmL-1 and a low limit of detection (LOD) of 0.32ngmL-1, which is far lower than the maximum residue limits (MRLs) settled by the European Commission. In addition, it exhibits excellent selectivity, high reproducibility with a relative standard deviation (RSD) of 1.1%, and good repeatability (RSD 1.1%). In real sample analysis recoveries ranged from 94.8 to 105% showing the proposed electrochemical sensor has high potential in practical applications. This work presents an effective and valuable pathway for the useof novel heterostructure in the biosensing field.

Temperature-dependent synthesis of MOF-derived Co@N-doped carbon nanotube nanocomposites toward accelerated reduction of 4-nitrophenol

Designing advanced catalysts with atomic level control over the heterointerfaces and active sites is of great importance for the boosted catalytic reduction reactions. Here, we show that Co nanoparticle-wrapped by N-doped carbon nanotube heterostructures synthesized by the temperature-dependent pyrolysis of zeolitic imidazolate framework-67 (ZIF-67) precursors have relatively higher catalytic activity toward the reduction of 4-nitrophenol. The well-constructed Co@N-doped carbon nanotube hybrid catalyst calcined at 435 °C exhibited catalytic reduction activity superior to those of nanocomposites calcined at other temperatures. The enhanced reduction of 4-nitrophenol performance may be attributed to strong synergistic interactions between well-defined Co nanoparticles and in-situ formed N-doped carbon nanotubes. It is proposed that N-doped carbon nanotubes not only act as the support for Co nanoparticles, but also provide protection for Co nanoparticles from aggregation and oxidation. Furthermore, N-doped carbon nanotubes can enhance the surface adsorption between the components to facilitate electron transfer due to the presence of doped nitrogen atoms. The catalyst also showed high stability with small losses in catalytic activity in recycled experiments, indicating great potential to be cost-effective non-precious metal-based catalysts for scalable and high-performance catalytic reduction reactions.

Optimized Thermoelectric Performance of Carbon Nanoparticle-Carbon Nanotube Heterostructures by Tuning Interface Barrier Energy.

Herein, thermoelectric carbon nanoparticle (CNP)-carbon nanotube (CNT) heterostructures are introduced as a promising flexible thermoelectric material. The optimal barrier energy between the CNP and CNT increases the Seebeck coefficient (S) of the heterostructures through the energy filtering effect. For optimized thermoelectric performance, the CNP-CNT barrier energy can be effectively tuned by controlling the work function of the CNPs. The optimized p-type CNP-CNT heterostructures exhibited S and power factor (PF) of 50.6 ± 1.4 μV K-1 and 400 ± 26 μW m-1 K-2, respectively. The n-type CNP-CNT heterostructures, optimized for another work function of the CNPs, exhibited S and PF of up to -37.5 ± 3.4 μV K-1 and 214 ± 42 μW m-1 K-2, respectively. The energy harvesting capability of a thermoelectric generator prepared using p- and n-type CNP-CNT heterostructures with optimized barrier energies is demonstrated. The thermoelectric generator with 10 p-type and 9 n-type thermoelectric elements exhibited a maximum output power of 0.12 μW from a ΔT of 5 K. This work shows a facile strategy for synthesizing thermoelectric CNP-CNT heterostructures with optimized energy filtering effects. Application to the thermoelectric device on a paper substrate is also discussed.

A versatile route for the synthesis of Pt-loaded mesoporous CNT heterostructure

A simple and versatile route for the synthesis of mesoporous carbon nanotube (CNT)-supported platinum/tungsten carbide (Pt/WC) nanoparticles (NPs) was set up via vapor deposition process. Amorphous CNT (α-CNT) was used to immobilize Pt/WC NPs. Platinum 2,4-pentanedionate, hexacarbonyltungsten and α-CNTs were selected as raw materials. Large density of W2C/Pt NPs was uniformly decorated on the wall of α-CNTs and W2C NPs were amorphous structured. The diameters of Pt NPs ranged from 3 to 6 nm, with mean diameter of about 4 nm. This approach provides an efficient method to fabricate carbides or other non-carbides metal NPs on CNT for the in situ synergistic fabrication of heterostructures.

From Highly Purified Boron Nitride to Boron Nitride‐Based Heterostructures: An Inorganic Precursor‐Based Strategy

AbstractThe current approaches used to fabricate hexagonal boron nitrides (h‐BN) from boron trioxide and urea always results in contamination of the h‐BN product with carbon/oxygen. Thus, discovering a facile way of mass producing high‐purity h‐BN remains a challenge. A simple yet highly efficient thermal treatment approach to large‐scale fabrication of nanoporous h‐BN with high yield, high purity, and high crystallinity is described using NaNH2 and NaBH4 as the oxygen‐ and carbon‐free precursors. The unique properties of inorganic metal salts, i.e., high melting point and strong electrostatic interaction with carbon substrates, render this strategy suitable for the production of homogeneous h‐BN/mesoporous carbon and h‐BN/carbon nanotube heterostructures of high crystallinity, high h‐BN dispersity, and with a strong interfacial effect. These unique features make them promising candidates for supercapacitor applications, resulting a significantly enhanced specific capacitance. This study provides new insight into the fabrication of high‐purity h‐BN and h‐BN‐based heterostructures thus expanding their application in the field of energy storage and transformation.

Correction: An evidence for an organic N-doped multiwall carbon nanotube heterostructure and its superior electrocatalytic properties for promising dye-sensitized solar cells

Correction for ‘An evidence for an organic N-doped multiwall carbon nanotube heterostructure and its superior electrocatalytic properties for promising dye-sensitized solar cells’ by Alvira Ayoub Arbab et al., J. Mater. Chem. A, 2018, DOI: 10.1039/c8ta00535d.

An evidence for an organic N-doped multiwall carbon nanotube heterostructure and its superior electrocatalytic properties for promising dye-sensitized solar cells

Mechanism of synthesis of an organic N-doped MWCNT heterostructure for Pt-free DSSCs.

First-principles study on the electronic and transport properties of periodically nitrogen-doped graphene and carbon nanotube superlattices

Prompted by recent reports on $\sqrt{3} \times \sqrt{3}$ graphene superlattices with intrinsic inter-valley interactions, we perform first-principles calculations to investigate the electronic properties of periodically nitrogen-doped graphene and carbon nanotube nanostructures. In these structures, nitrogen atoms substitute one-sixth of the carbon atoms in the pristine hexagonal lattices with exact periodicity to form perfect $\sqrt{3} \times \sqrt{3}$ superlattices of graphene and carbon nanotubes. Multiple nanostructures of $\sqrt{3} \times \sqrt{3}$ graphene ribbons and carbon nanotubes are explored, and all configurations show nonmagnetic and metallic behaviors. The transport properties of $\sqrt{3} \times \sqrt{3}$ graphene and carbon nanotube superlattices are calculated utilizing the non-equilibrium Green's function formalism combined with density functional theory. The transmission spectrum through the pristine and $\sqrt{3} \times \sqrt{3}$ armchair carbon nanotube heterostructure shows quantized behavior under certain circumstances.

3D urchin-like black TiO2−x/carbon nanotube heterostructures as efficient visible-light-driven photocatalysts

3D urchin-like black TiO2−x/carbon nanotube heterostructures with a narrow bandgap and Ti3+ self-doping exhibit excellent visible-light-driven photocatalytic performance.

One-dimensional barium titanate coated multi-walled carbon nanotube heterostructures: synthesis and electromagnetic absorption properties

BaTiO3@MWCNT heterostructures have been explored as microwave absorbers, which showed the maximum reflection loss with value of −25.7 dB at 12.1 GHz for 40 wt% loadings in wax, and the frequency bandwidth less than −20 dB is from 11.3 to 13.8 GHz.

Invited Presentation: Carbon Nanotube Heterostructure Devices

Improvements in carbon nanotube (CNT) monodispersity have yielded corresponding enhancements in the performance of electronic, optoelectronic, sensing, and energy technologies [1]. However, in all of these cases, CNTs are just one of many materials that are employed, suggesting that further device improvements can be achieved by focusing on the careful integration of disparate materials with CNTs. In this talk, several examples will be provided where careful attention to materials integration enables unprecedented opportunities for CNT heterostructure devices. For example, the traditional trade-off between on/off ratio and mobility in semiconducting CNT thin-film transistors is overcome by replacing conventional inorganic gate dielectrics with hybrid organic-inorganic self-assembled nanodielectrics, yielding on/off ratios approaching 106 while concurrently achieving mobilities of ~150 cm2/V-s [2,3]. Similarly, the utilization of unconventional gate electrodes (e.g., Ni) allows the threshold voltage of semiconducting CNT thin-film transistors to be shifted, which enables the realization of p-type enhancement-mode devices. By further integrating benzyl viologen with Ni-gated semiconducting CNT thin-film transistors, complementary n-type enhancement-mode devices can also be demonstrated. The integration of enhancement mode p-type and n-type CNT thin-film transistors then allows for CNT CMOS logic gates to be fabricated with sub-nanowatt static power dissipation and full rail-to-rail voltage swing [4]. Finally, p-type semiconducting CNT thin films are integrated with n-type single-layer MoS2 to form p-n heterojunction diodes [5]. The atomically thin nature of single-layer MoS2 implies that an applied gate bias can electrostatically modulate the doping on both sides of the p-n heterojunction concurrently, thereby providing 5 orders of magnitude gate-tunability over the diode rectification ratio in addition to unprecedented anti-ambipolar behavior when operated as a three-terminal device. In addition, since CNTs and single-layer MoS2 are direct band gap semiconductors, the resulting p-n heterojunctions show a strong and ultrafast photoresponse at near-infrared and visible wavelengths. Overall, this work establishes that CNT-based technology can be substantially enhanced and diversified into new areas through precise integration into heterostructure devices.[1] D. Jariwala, V. K. Sangwan, L. J. Lauhon, T. J. Marks, and M. C. Hersam, “Carbon nanomaterials for electronics, optoelectronics, photovoltaics, and sensing,” Chem. Soc. Rev., 42, 2824 (2013).[2] V. K. Sangwan, R. P. Ortiz, J. M. P. Alaboson, J. D. Emery, M. J. Bedzyk, L. J. Lauhon, T. J. Marks, and M. C. Hersam, “Fundamental performance limits of carbon nanotube thin-film transistors achieved using hybrid molecular dielectrics,” ACS Nano, 6, 7480 (2012).[3] K. Everaerts, J. D. Emery, D. Jariwala, H. J. Karmel, V. K. Sangwan, P. L. Prabhumirashi, M. L. Geier, J. J. McMorrow, M. J. Bedzyk, A. Facchetti, M. C. Hersam, and T. J. Marks, “Ambient-processable high-capacitance hafnia-organic self-assembled nanodielectrics,” J. Am. Chem. Soc., 135, 8926 (2013). [4] M. L. Geier, P. L. Prabhumirashi, J. J. McMorrow, W. Xu, J.-W. T. Seo, K. Everaerts, C. H. Kim, T. J. Marks, and M. C. Hersam, “Subnanowatt carbon nanotube complementary logic enabled by threshold voltage control,” Nano Lett., 13, 4810 (2013). [5] D. Jariwala, V. K. Sangwan, C.-C. Wu, P. L. Prabhumirashi, M. L. Geier, T. J. Marks, L. J. Lauhon, and M. C. Hersam, “Gate-tunable carbon nanotube-MoS2 heterojunction p-n diode,” Proc. Nat. Acad. Sci. USA, 110, 18076 (2013).

Silicon carbide/carbon nanotube heterostructures: Controllable synthesis, dielectric properties and microwave absorption

Carbon nanotube (CNTs) based heterostructures, such as CNT/metal, CNT/polymer, CNT/semiconductor, are attractive for the combined properties and unique applications in cutting-edge electronics and devices. Here in this work, nanostructured beta-silicon carbide (β-SiC)/CNTs heterostructures were synthesized by carbothermal reduction of silica (SiO2) and CNTs with diverse mixing ratios of nC:nSi. Different techniques were carried out for the characterization of the structures and morphologies of the achieved heterostructures, demonstrating dramatic different morphologies which were associated with the different starting ratios of the nC:nSi. The dielectric properties and microwave absorption of wax-based composites were investigated. The parameters for morphologically controllable synthesis and related mechanism for dielectric properties and electromagnetic attenuation were discussed.

CuO Necklace: Controlled Synthesis of a Metal Oxide and Carbon Nanotube Heterostructure for Enhanced Lithium Storage Performance

Metal oxide and nanocarbon heterostructures provide a powerful strategy to materials innovation because judicious combination of different materials may afford collective properties that are otherwise unattainable. However, design and fabrication of spatially patterned heterostructures has been still challenging. Here, we develop a facile approach to synthesize a CuO and carbon nanotube necklace-like heterostructure in solution for enhanced lithium storage performance. Observations confirm that propagative sidewall alkylcarboxylation of carbon nanotubes in liquid ammonia allows the CuO nanospheres to grow on the functional defect sites introduced by the functionalization. Such a method does not require surfactants and is highly scalable. The resulting materials show high lithium ion storage capacities (stable at 500 mAh g–1) and enhanced cycling performance as a lithium-ion battery anode. The improved performance is attributed to the necklace-like nanostructure, which provides an electrical channel as well as excess room to accommodate the volume changes of CuO during electrochemical cycling.

Co3O4–carbon nanotube heterostructures with bead-on-string architecture for enhanced lithium storage performance

In this report, alkylcarboxyl group-decorated carbon nanotubes (CNTs) with clustered functionalization patterns are achieved based on a modified Birch reduction in liquid ammonia. By using these functional CNTs (f-CNTs), a new type of Co3O4-CNT heterostructure is prepared via a simple hydrothermal method. SEM and TEM analyses reveal that the as-synthesized Co3O4-CNT heterostructures exhibit bead-on-string architecture, in which the Co3O4 spheres are threaded with CNTs. A possible growth mechanism is proposed to explain the formation of these Co3O4-CNT heterostructures. The electrochemical properties of the Co3O4-CNT heterostructures as anode materials for lithium ion batteries are investigated. The Co3O4-CNT heterostructures display high electrochemical activity, good cycle stability and improved rate performance. Such a large improvement of the electrochemical performance can be related to the robust necklace-like architectures which possess properties such as high mechanical stability, excellent electric conductivity and good strain accommodation.

Giant Enhancement of Field Emission from Selectively Edge Grown ZnO–Carbon Nanotube Heterostructure Arrays via Diminishing the Screen Effect

Novel selectively edge grown ZnO–carbon nanotube (CNT) heterostructure field emission (FE) arrays have been fabricated by a facile and repeatable two-step process. First, with the combined effect from a ZnO seed layer and a passivation layer for nanorod growth, ZnO nanorods could only grow on the edge of a 4 μm diameter circle. Meanwhile, the local morphology such as ZnO nanorod density, uniformity, and growth direction can be modulated by the thickness of ZnO seed layer. With this adjustment, the FE performance of the ZnO nanorod ring pattern arrays is significantly improved. Then CNTs were radically grown on the surface of the ZnO nanorod ring pattern arrays. As a consequence of all these optimizations, the lowest turn-on field of 2.1 V/μm, threshold field of 3.19 V/μm, and a current density of 7 mA/cm2 at a field of 4.95 V/μm were ultimately obtained. Via calculating the electrostatic field distribution, it was found that this giant enhancement of FE performance is due to the typical morphology which c...

Electrophoretic deposition and characterization of Eu 2O 3 nanocrystal—Carbon nanotube heterostructures

Electrophoretic deposition (EPD) was employed to assemble a layered architecture of multi-walled carbon nanotube (CNT) mats and europium oxide nanocrystal (NC) films. CNT mats were produced via low field–high current EPD, while NC films were deposited via high field–low current EPD. The two EPD techniques were integrated in an alternating sequence to create CNT mat–NC film–CNT mat heterostructures with sharp interfaces. The EPD techniques produced uniformly porous CNT mats and densely packed NC films. Morphology and surface coverage of the films were investigated using scanning electron microscopy (SEM), while elemental characterization was performed using energy dispersive spectroscopy (EDS). Photoluminescence (PL) spectroscopy measurements were conducted on the NC suspension and the NC films to confirm film formation. Capacitance–voltage (CV) measurements were performed to probe energy-storage capabilities of the layered architecture.

UV photovoltaic cells based on conjugated ZnO quantum dot/multiwalled carbon nanotube heterostructures

In situ growth of ZnO quantum dots (QDs) on the surface of multiwalled carbon nanotubes (MWCNTs) was realized via a mild solution-process method, which resulted in an improvement in photoinduced charge separation and transport of carriers to the collecting electrode. The charge transfer efficiency was significantly increased by more than 90% due to the conjugation of ZnO QDs with MWCNTs, as confirmed by photoluminescence measurements. Ultraviolet photovoltaic cells based on the charge transfer at the ZnO QD-MWCNT heterostructures were fabricated, and their power conversion efficiency was measured to be above 1%.