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Vertically aligned carbon nanotubes

Guan Wu, Pengfeng Tan, Dongxing Wang, Zhe Li, Lu Peng, Ying Hu, Caifeng Wang, Wei Zhu, Su Chen, Wei Chen
Supercapacitors, which store electrical energy through reversible ion on the surface of conductive electrodes have gained enormous attention for variously portable energy storage devices. Since the capacitive performance is mainly determined by the structural and electrochemical properties of electrodes, the electrodes become more crucial to higher performance. However, due to the disordered microstructure and low electrochemical activity of electrode for ion tortuous migration and accumulation, the supercapacitors present relatively low capacitance and energy density...
March 8, 2017: Scientific Reports
Theerapol Thurakitseree, Christian Kramberger, Pisith Singjai, Shigeo Maruyama
Structure control such as diameter changes along single-walled carbon nanotubes (SWNTs) can be achieved in arrays of vertically aligned (VA-) SWNTs by switching the feedstock during growth. The local nature of the macroscopic transition from one diameter to another is then questioned as one can either envisage seamless transitions or discontinuous individual SWNTs. Here, we demonstrate that encapsulated molecules can serve as markers to doubtlessly identify seamless interconnections in macroscopic samples. A migration of nitrogen molecules inside the continuous SWNTs is observed using bulk scale measurements on double-layered SWNT arrays synthesized from different carbon/nitrogen feedstocks...
March 7, 2017: Nanoscale
Jiadong Sheng, Qi Zhu, Xian Zeng, Zhaohui Yang, Xiaohua Zhang
Ion transport plays an important role in solar-to-electricity conversion, drug delivery, and a variety of biological processes. Carbon nanotube (CNT) is a promising material as an ion transporter in the applications of the mimicking of natural ion channels, desalination, and energy harvesting. Here, we demonstrate a unique, enhanced ion transport through a vertically aligned multiwall CNT membrane after the application of an electric potential across CNT membranes. Interestingly, electrowetting arising from the application of an electric potential is critical for the enhancement of overall ion transport rate through CNT membranes...
March 14, 2017: ACS Applied Materials & Interfaces
Hong Zhu, Fengxia Chang, Zhiwei Zhu
How to align the single-walled carbon nanotubes (SWCNTs) onto the electrode vertically and to control their density and orientation are still a major challenge. Theoretically, properly selected chiral SWCNTs can discriminate enantiomers through their different dielectric response to the adsorption of chiral species, few reports can confirm this theoretic model. Herein, we presented a new strategy to fabricate SWCNTs array-based electrochemical chiral sensor. Carboxylated chiral SWCNTs were vertically attached to the oxidized glass carbon electrode with ethylenediamine as a linker by electrosynthesis...
May 1, 2017: Talanta
Wojciech Szmyt, Carlos Guerra, Ivo Utke
In this work we modelled the diffusive transport of a dilute gas along arrays of randomly distributed, vertically aligned nanocylinders (nanotubes or nanowires) as opposed to gas diffusion in long pores, which is described by the well-known Knudsen theory. Analytical expressions for (i) the gas diffusion coefficient inside such arrays, (ii) the time between collisions of molecules with the nanocylinder walls (mean time of flight), (iii) the surface impingement rate, and (iv) the Knudsen number of such a system were rigidly derived based on a random-walk model of a molecule that undergoes memoryless, diffusive reflections from nanocylinder walls assuming the molecular regime of gas transport...
2017: Beilstein Journal of Nanotechnology
Josefine Hirschfeld, Eser M Akinoglu, Dieter C Wirtz, Achim Hoerauf, Isabelle Bekeredjian-Ding, Søren Jepsen, El-Mustapha Haddouti, Andreas Limmer, Michael Giersig
Bacterial biofilms cause a considerable amount of prosthetic joint infections every year, resulting in morbidity and expensive revision surgery. To address this problem, surface modifications of implant materials such as carbon nanotube (CNT) coatings have been investigated in the past years. CNTs are biologically compatible and can be utilized as drug delivery systems. In this study, multi-walled carbon nanotube (MWCNT) coated TiAl6V4 titanium alloy discs were fabricated and impregnated with Rifampicin, and tested for their ability to prevent biofilm formation over a period of ten days...
January 20, 2017: Nanomedicine: Nanotechnology, Biology, and Medicine
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
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