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Vertically aligned carbon nanotubes

Heena K Mutha, Yuan Lu, Itai Y Stein, H Jeremy Cho, Matthew E Suss, Tahar Laoui, Carl V Thompson, Brian L Wardle, Evelyn N Wang
Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes...
December 29, 2016: Nanotechnology
Changjian Zhou, Richard Senegor, Zachary Baron, Yihan Chen, Salahuddin Raju, Anshul A Vyas, Mansun Chan, Yang Chai, Cary Y Yang
Carbon nanotubes (CNTs) and graphene are potential candidates for future interconnect materials. CNTs are promising on-chip via interconnect materials due to their readily formed vertical structures, their current-carrying capacity, which is much larger than existing on-chip interconnect materials such as copper and tungsten, and their demonstrated ability to grow in patterned vias with sub-50 nm widths; meanwhile, graphene is suitable for horizontal interconnects. However, they both present the challenge of having high-resistance contacts with other conductors...
February 3, 2017: Nanotechnology
Takashi Tsuji, Kenji Hata, Don N Futaba, Shunsuke Sakurai
An unexpected 5000% increase in growth efficiency and high (95%) single-wall selectivity synthesis of vertically aligned carbon nanotubes (CNTs) was shown from Fe catalysts supported on a sputtered MgO underlayer from a simple underlayer treatment, i.e., annealing treatment. In this way, millimeter-scale single-wall carbon nanotube "forests" could be synthesized in a 10 min time, which has never been previously reported for MgO catalyst underlayer or any underlayer besides Al2O3. This level of efficiency and characterized SWCNT properties were similar to those grown using Al2O3 underlayers...
December 28, 2016: Journal of the American Chemical Society
Yixuan Zhou, Yiwen E, Xinlong Xu, Weilong Li, Huan Wang, Lipeng Zhu, Jintao Bai, Zhaoyu Ren, Li Wang
Spatial dispersion effect of aligned carbon nanotubes (CNTs) in the terahertz (THz) region has significance for both theoretical and applied consideration due to the unique intrinsically anisotropic physical properties of CNTs. Herein, we report the angular dependent reflection of p-polarized THz wave from vertically aligned multi-walled CNT arrays in both experiment and theory. The spectra indicate that the reflection depends on the film thickness of vertically aligned CNTs, the incident angle, and the frequency...
December 14, 2016: Scientific Reports
Heena K Mutha, Yuan Lu, Itai Stein, H Jeremy Cho, Matthew Suss, Tahar Laoui, Carl Thompson, Brian Wardle, Evelyn Wang
Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes...
December 13, 2016: Nanotechnology
Sanghyun Hong, Troy Lundstrom, Ranajay Ghosh, Hamed Abdi, Ji Hao, Sun Kyoung Jeoung, Paul Su, Jonghwan Suhr, Ashkan Vaziri, Nader Jalili, Yung Joon Jung
We have created a multifunctional dry adhesive film with transferred vertically aligned carbon nanotubes (VA-CNTs). This unique VA-CNT film was fabricated by a multistep transfer process, converting the flat and uniform bottom of VA-CNTs grown on atomically flat silicon wafer substrates into the top surface of an adhesive layer. Unlike as-grown VA-CNTs, which have a nonuniform surface, randomly entangled CNT arrays, and a weak interface between the CNTs and substrates, this transferred VA-CNT film shows an extremely high coefficient of static friction (COF) of up to 60 and a shear adhesion force 30 times higher (12 N/cm(2)) than that of the as-grown VA-CNTs under a very small preloading of 0...
December 14, 2016: ACS Applied Materials & Interfaces
Viswanath Balakrishnan, Mostafa Bedewy, Eric R Meshot, Sebastian W Pattinson, Erik S Polsen, Fabrice Laye, Dmitri N Zakharov, Eric A Stach, A John Hart
The properties of carbon nanotube (CNT) networks and analogous materials comprising filamentary nanostructures are governed by the intrinsic filament properties and their hierarchical organization and interconnection. As a result, direct knowledge of the collective dynamics of CNT synthesis and self-organization is essential to engineering improved CNT materials for applications such as membranes and thermal interfaces. Here, we use real-time environmental transmission electron microscopy (E-TEM) to observe nucleation and self-organization of CNTs into vertically aligned forests...
December 27, 2016: ACS Nano
Hangbo Zhao, Christine Jacob, Howard A Stone, A John Hart
Understanding of the liquid imbibition dynamics in nanoporous materials is important to advances in chemical separations, phase change heat transfer, electrochemical energy storage, and diagnostic assays. We study the liquid imbibition behavior in films of ceramic-coated vertically aligned carbon nanotubes (CNTs). The nanoscale porosity of the films is tuned by conformal ceramic coating via atomic layer deposition (ALD), enabling stable liquid imbibition and precise measurement of the imbibition dynamics without capillary densification of the CNTs...
December 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Wei-Tsung Chuang, Yan-Ming Hsu, En-Li Lin, I-Ming Lin, Ya-Sen Sun, Yeo-Wan Chiang, Chun-Jen Su, Yao-Chang Lee, U-Ser Jeng
In this work, we introduce a facile method based on host-guest chemistry to synthesize a range of nanostructured TiO2 materials using supramolecular templates of a dendron-jacketed block copolymer (DJBCP). The DJBCP is composed of amphiphilic dendrons (4'-(3,4,5-tridodecyloxybenzoyloxy)benzoic acid, TDB) selectively incorporated into a P4VP block of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) via hydrogen bonding. The PS-b-P4VP host acts as a structure-directing template, while the guest molecules (TDB) assist the self-assembly nanostructures and zone-axis alignment, resulting in the nanostructured template of vertically oriented cylinders formed via successive phase transformations from Im3̅m to R3̅m to P6mm upon thermal annealing in the doctor-blade-cast film...
December 7, 2016: ACS Applied Materials & Interfaces
Tugba Ceren Gokoglan, Saniye Soylemez, Melis Kesik, Itir Bakis Dogru, Onur Turel, Recep Yuksel, Husnu Emrah Unalan, Levent Toppare
A novel flexible glucose biosensor using vertically aligned carbon nanotubes (VACNT) and a conjugated polymer (CP) was fabricated. A scaffold based on VACNT grown on aluminum foil (VACNT-Al foil) with poly (9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl)-end capped with 2,5-diphenyl-1,2,4-oxadiazole (PFLO) was used as the immobilization matrix for the glucose biosensor. Glucose oxidase (GOx) was immobilized on a modified indium tin oxide (ITO) coated polyethylene terephthalate (PET) electrode surface. The biosensor response at a potential of -0...
April 1, 2017: Food Chemistry
Valerie J Scott, Harish Manohara, Risaku Toda, Linda Del Castillo, Rakesh Murthy, Jerry Mulder, Eshwari Murty, M Clark Thompson
Robust carbon nanotube (CNT)-based cold cathodes were fabricated on titanium (Ti) substrates. Methods to grow vertically aligned CNTs  directly on Ti substrates were developed. These cathodes can be treated post-growth at elevated temperatures under inert atmosphere which causes the surface-grown CNTs to become anchored to the substrate surface. These samples offer improvements in field emission properties over previously studied silicon (Si) substrate-based cathodes with no anchoring, displaying low threshold voltages, high field enhancement factors, and long operating lifetimes...
November 9, 2016: Nanotechnology
Saeed Rafizadeh-Tafti, Mohammad Hossein Haqiqatkhah, Mehrdad Saviz, Mohsen Janmaleki, Reza Faraji Dana, Somayeh Zanganeh, Mohammad Abdolahad
A highly sensitive impedimetric bio-chip based on vertically aligned multiwall carbon nanotubes (VAMWCNTs), was applied in direct interaction with lung cancer cells. Our tool provided both inducing and monitoring the bioelectrical changes in the cells initiated by electromagnetic (EM) wave stimulation. EM wave of 940MHz frequency with different intensities was used. Here, wave ablation might accumulate electrical charge on the tips of nanotubes penetrated into cell's membrane. The charge might induce ionic exchanges into the cell and cause alterations in electrical states of the membrane...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Jakob Buchheim, Hyung Gyu Park
Polymer melt infiltration is one of the feasible methods for manufacturing filter membranes out of carbon nanotubes (CNTs) on large scales. Practically, however, its process suffers from low yields, and the mechanism behind this failure is rather poorly understood. Here, we investigate a failure mechanism of polymer melt infiltration of vertical aligned (VA-) CNTs. In penetrating the VA-CNT interstices, polymer melts exert a capillarity-induced attractive force laterally on CNTs at the moving meniscus, leading to locally agglomerated macroscale bunches...
October 13, 2016: Nanotechnology
Yin-Ting Yeh, Yi Tang, Aswathy Sebastian, Archi Dasgupta, Nestor Perea-Lopez, Istvan Albert, Huaguang Lu, Mauricio Terrones, Si-Yang Zheng
Viral infectious diseases can erupt unpredictably, spread rapidly, and ravage mass populations. Although established methods, such as polymerase chain reaction, virus isolation, and next-generation sequencing have been used to detect viruses, field samples with low virus count pose major challenges in virus surveillance and discovery. We report a unique carbon nanotube size-tunable enrichment microdevice (CNT-STEM) that efficiently enriches and concentrates viruses collected from field samples. The channel sidewall in the microdevice was made by growing arrays of vertically aligned nitrogen-doped multiwalled CNTs, where the intertubular distance between CNTs could be engineered in the range of 17 to 325 nm to accurately match the size of different viruses...
October 2016: Science Advances
Moses Oguntoye, Michael Johnson, Lawrence R Pratt, Noshir S Pesika
We explore the use of vertically aligned carbon nanotube (VACNT) arrays as an electrode in a triboelectric nanogenerator (TENG) that harvests mechanical energy and converts it to electrical energy. When VACNT arrays, 1 cm2 in area, are mechanically contacted with PET and PTFE counter electrodes in vertical contact-separation mode, currents up to 0.16 µA and 0.21 µA, and voltages up to 1.42 V and 3.20 V are obtained, respectively. The VACNT TENG output remains stable even after over 20,000 continuous contact cycles...
October 4, 2016: ACS Applied Materials & Interfaces
Tomohiro Tajiri, Ryosuke Matsuzaki, Yoshinobu Shimamura
The flow rate of water through carbon nanotube (CNT) membranes is considerably large. Hence, CNT membranes can be used in nanofluidic applications. In this work, we performed a molecular dynamics (MD) simulation of the introduction of water into CNTs in the CNT membranes, especially in vertically aligned CNT forests. The results showed that the Knudsen number (Kn) increased with an increasing volume fraction of CNT (VC) and was greater than 10(-3) for each VC. Beyond this value, the flow became a slip flow...
August 26, 2016: Scientific Reports
Mingkai Liu, Yuqing Liu, Yuting Zhang, Yiliao Li, Peng Zhang, Yan Yan, Tianxi Liu
A novel binder-free graphene - carbon nanotubes - SnO2 (GCNT-SnO2) aerogel with vertically aligned pores was prepared via a simple and efficient directional freezing method. SnO2 octahedrons exposed of {221} high energy facets were uniformly distributed and tightly anchored on multidimensional graphene/carbon nanotube (GCNT) composites. Vertically aligned pores can effectively prevent the emersion of "closed" pores which cannot load the active SnO2 nanoparticles, further ensure quick immersion of electrolyte throughout the aerogel, and can largely shorten the transport distance between lithium ions and active sites of SnO2...
August 11, 2016: Scientific Reports
Samarth Trivedi, Kamal Alameh
In this paper, vertically aligned carbon nanotube (VACNT) membranes of different densities are developed and their performances are investigated. VACNT arrays of densities 5 × 10(9), 10(10), 5 × 10(10) and 10(11) tubes cm(-2), are initially grown on 1 cm × 1 cm silicon substrates using chemical vapour deposition. A VACNT membrane is realised by attaching a 300 μm-thick 1 cm × 1 cm VACNT array on silicon to a 4″ glass substrate, applying polydimethylsiloxane (PDMS) through spin coating to fill the gaps between the VACNTs, and using a microtome to slice the VACNT-PDMS composite into 25-μm-thick membranes...
2016: SpringerPlus
O Yilmazoglu, S Yadav, D Cicek, J J Schneider
A design for a unique artificial-hair-cell-type sensor (AHCTS) based entirely on 3D-structured, vertically aligned carbon nanotube (CNT) bundles is introduced. Standard microfabrication techniques were used for the straightforward micro-nano integration of vertically aligned carbon nanotube arrays composed of low-layer multi-walled CNTs (two to six layers). The mechanical properties of the carbon nanotube bundles were intensively characterized with regard to various substrates and CNT morphology, e.g. bundle height...
September 9, 2016: Nanotechnology
Shota Takagiwa, Osamu Kanasugi, Kentaro Nakamura, Masahito Kushida
In order to apply vertically-aligned carbon nanotubes (VA-CNTs) to a new Pt supporting material of polymer electrolyte fuel cell (PEFC), number density and outer diameter of CNTs must be controlled independently. So, we employed Langmuir-Blodgett (LB) technique for depositing CNT growth catalysts. A Fe nanoparticle (NP) was used as a CNT growth catalyst. In this study, we tried to thicken VA-CNT carpet height and inhibit thermal aggregation of Fe NPs by using Al2O3/Al/SiO2/Si substrate. Fe NP LB films were deposited on three typed of substrates, SiO2/Si, as-deposited Al2O3/Al/SiO2/Si and annealed Al2O3/Al/SiO2/Si at 923 K in Ar atmosphere of 16 Pa...
April 2016: Journal of Nanoscience and Nanotechnology
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