WorldWideScience

Sample records for aligned carbon nanofiber

  1. Purification process for vertically aligned carbon nanofibers

    Science.gov (United States)

    Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

    2003-01-01

    Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

  2. Vertically Aligned Carbon Nanofiber based Biosensor Platform for Glucose Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Al Mamun, Khandaker A.; Tulip, Fahmida S.; MacArthur, Kimberly; McFarlane, Nicole; Islam, Syed K.; Hensley, Dale

    2014-03-01

    Vertically aligned carbon nanofibers (VACNFs) have recently become an important tool for biosensor design. Carbon nanofibers (CNF) have excellent conductive and structural properties with many irregularities and defect sites in addition to exposed carboxyl groups throughout their surfaces. These properties allow a better immobilization matrix compared to carbon nanotubes and offer better resolution when compared with the FET-based biosensors. VACNFs can be deterministically grown on silicon substrates allowing optimization of the structures for various biosensor applications. Two VACNF electrode architectures have been employed in this study and a comparison of their performances has been made in terms of sensitivity, sensing limitations, dynamic range, and response time. The usage of VACNF platform as a glucose sensor has been verified in this study by selecting an optimum architecture based on the VACNF forest density. Read More: http://www.worldscientific.com/doi/abs/10.1142/S0129156414500062

  3. Epitaxial Growth of Aligned and Continuous Carbon Nanofibers from Carbon Nanotubes.

    Science.gov (United States)

    Lin, Xiaoyang; Zhao, Wei; Zhou, Wenbin; Liu, Peng; Luo, Shu; Wei, Haoming; Yang, Guangzhi; Yang, Junhe; Cui, Jie; Yu, Richeng; Zhang, Lina; Wang, Jiaping; Li, Qunqing; Zhou, Weiya; Zhao, Weisheng; Fan, Shoushan; Jiang, Kaili

    2017-02-28

    Exploiting the superior properties of nanomaterials at macroscopic scale is a key issue of nanoscience. Different from the integration strategy, "additive synthesis" of macroscopic structures from nanomaterial templates may be a promising choice. In this paper, we report the epitaxial growth of aligned, continuous, and catalyst-free carbon nanofiber thin films from carbon nanotube films. The fabrication process includes thickening of continuous carbon nanotube films by gas-phase pyrolytic carbon deposition and further graphitization of the carbon layer by high-temperature treatment. As-fabricated nanofibers in the film have an "annual ring" cross-section, with a carbon nanotube core and a graphitic periphery, indicating the templated growth mechanism. The absence of a distinct interface between the carbon nanotube template and the graphitic periphery further implies the epitaxial growth mechanism of the fiber. The mechanically robust thin film with tunable fiber diameters from tens of nanometers to several micrometers possesses low density, high electrical conductivity, and high thermal conductivity. Further extension of this fabrication method to enhance carbon nanotube yarns is also demonstrated, resulting in yarns with ∼4-fold increased tensile strength and ∼10-fold increased Young's modulus. The aligned and continuous features of the films together with their outstanding physical and chemical properties would certainly promote the large-scale applications of carbon nanofibers.

  4. Preparation and Characterization of Highly Aligned Carbon Nanotubes/Polyacrylonitrile Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Yanhua Song

    2017-01-01

    Full Text Available In the electrospinning process, a modified parallel electrode method (MPEM, conducted by placing a positively charged ring between the needle and the parallel electrode collector, was used to fabricate highly aligned carbon nanotubes/polyacrylonitrile (CNTs/PAN composite nanofibers. Characterizations of the samples—such as morphology, the degree of alignment, and mechanical and conductive properties—were investigated by a combination of scanning electron microscopy (SEM, transmission electron microscopy (TEM, universal testing machine, high-resistance meter, and other methods. The results showed the MPEM could improve the alignment and uniformity of electrospun CNTs/PAN composite nanofibers, and enhance their mechanical and conductive properties. This meant the successful preparation of highly aligned CNT-reinforced PAN nanofibers with enhanced physical properties, suggesting their potential application in appliances and communication areas.

  5. Vertically aligned carbon nanofiber as nano-neuron interface for monitoring neural function

    Energy Technology Data Exchange (ETDEWEB)

    Ericson, Milton Nance [ORNL; McKnight, Timothy E [ORNL; Melechko, Anatoli Vasilievich [ORNL; Simpson, Michael L [ORNL; Morrison, Barclay [ORNL; Yu, Zhe [Columbia University

    2012-01-01

    Neural chips, which are capable of simultaneous, multi-site neural recording and stimulation, have been used to detect and modulate neural activity for almost 30 years. As a neural interface, neural chips provide dynamic functional information for neural decoding and neural control. By improving sensitivity and spatial resolution, nano-scale electrodes may revolutionize neural detection and modulation at cellular and molecular levels as nano-neuron interfaces. We developed a carbon-nanofiber neural chip with lithographically defined arrays of vertically aligned carbon nanofiber electrodes and demonstrated its capability of both stimulating and monitoring electrophysiological signals from brain tissues in vitro and monitoring dynamic information of neuroplasticity. This novel nano-neuron interface can potentially serve as a precise, informative, biocompatible, and dual-mode neural interface for monitoring of both neuroelectrical and neurochemical activity at the single cell level and even inside the cell.

  6. Understanding greater cardiomyocyte functions on aligned compared to random carbon nanofibers in PLGA

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    Asiri AM

    2014-12-01

    Full Text Available Abdullah M Asiri,1 Hadi M Marwani,1 Sher Bahadar Khan,1 Thomas J Webster1,2 1Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia; 2Department of Chemical Engineering, Northeastern University, Boston, MA, USA Abstract: Previous studies have demonstrated greater cardiomyocyte density on carbon nanofibers (CNFs aligned (compared to randomly oriented in poly(lactic-co-glycolic acid (PLGA composites. Although such studies demonstrated a closer mimicking of anisotropic electrical and mechanical properties for such aligned (compared to randomly oriented CNFs in PLGA composites, the objective of the present in vitro study was to elucidate a deeper mechanistic understanding of how cardiomyocyte densities recognize such materials to respond more favorably. Results showed lower wettability (greater hydrophobicity of CNFs embedded in PLGA compared to pure PLGA, thus providing evidence of selectively lower wettability in aligned CNF regions. Furthermore, the results correlated these changes in hydrophobicity with increased adsorption of fibronectin, laminin, and vitronectin (all proteins known to increase cardiomyocyte adhesion and functions on CNFs in PLGA compared to pure PLGA, thus providing evidence of selective initial protein adsorption cues on such CNF regions to promote cardiomyocyte adhesion and growth. Lastly, results of the present in vitro study further confirmed increased cardiomyocyte functions by demonstrating greater expression of important cardiomyocyte biomarkers (such as Troponin-T, Connexin-43, and α-sarcomeric actin when CNFs were aligned compared to randomly oriented in PLGA. In summary, this study provided evidence that cardiomyocyte functions are improved on CNFs aligned in PLGA compared to randomly oriented in PLGA since CNFs are more hydrophobic than PLGA and attract the adsorption of key proteins (fibronectin, laminin, and vironectin that are known to promote cardiomyocyte adhesion

  7. A Glucose Biosensor Using CMOS Potentiostat and Vertically Aligned Carbon Nanofibers.

    Science.gov (United States)

    Al Mamun, Khandaker A; Islam, Syed K; Hensley, Dale K; McFarlane, Nicole

    2016-08-01

    This paper reports a linear, low power, and compact CMOS based potentiostat for vertically aligned carbon nanofibers (VACNF) based amperometric glucose sensors. The CMOS based potentiostat consists of a single-ended potential control unit, a low noise common gate difference-differential pair transimpedance amplifier and a low power VCO. The potentiostat current measuring unit can detect electrochemical current ranging from 500 nA to 7 [Formula: see text] from the VACNF working electrodes with high degree of linearity. This current corresponds to a range of glucose, which depends on the fiber forest density. The potentiostat consumes 71.7 [Formula: see text] of power from a 1.8 V supply and occupies 0.017 [Formula: see text] of chip area realized in a 0.18 [Formula: see text] standard CMOS process.

  8. A facile route for controlled alignment of carbon nanotube-reinforced, electrospun nanofibers using slotted collector plates

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    G. R. Rakesh

    2015-02-01

    Full Text Available A facile route for controlled alignment of electrospun multiwalled carbon nanotube (MWCNT-reinforced Polyvinyl Alcohol (PVA nanofibers using slotted collector geometries has been realized. The process is based on analytical predictions using electrostatic field analysis for envisaging the extent of alignment of the electrospun fibers on varied collector geometries. Both the experimental and theoretical studies clearly indicate that the introduction of an insulating region into a conductive collector significantly influences the electrostatic forces acting on a charged fiber. Among various collector geometries, rectangular slotted collectors with circular ends showed good fiber alignment over a large collecting area. The electrospun fibers produced by this process were characterized by Atomic Force Microscopy (AFM, High Resolution Transmission Electron Microscopy (HRTEM, Scanning Electron Microscopy (SEM and Optical Microscopy. Effects of electrospinning time and slot widths on the fiber alignment have been analyzed. PVA-MWCNT nanofibers were found to be conducting in nature owing to the presence of reinforced MWCNTs in PVA matrix. The method can enable the direct integration of aligned nanofibers with controllable configurations, and significantly simplify the production of nanofibersbased devices.

  9. Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

    Institute of Scientific and Technical Information of China (English)

    Sang-Gook KIM; Sooh-Yung KIM; Hytmg-Woo LEE

    2011-01-01

    The etching effect of ammonia (NH3) on the growth of vertically aligned nanotubes/nanofibers (CNTs) was investigated by direct-current plasma enhanced chemical vapor deposition (DC-PECVD). NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etchingis different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth. the single strand CNT growth requires shorter etching time (5 min) than large catalytic patterns (10 min) since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy (HTEM) shows fishbone structure of CNTs grown by PECVD.

  10. Aligned Layers of Silver Nano-Fibers

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    Andrii B. Golovin

    2012-02-01

    Full Text Available We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.

  11. Vertically Aligned Carbon Nanofiber as Nano-Neuron Interface for Monitoring Neural Function

    OpenAIRE

    Yu, Zhe; McKnight, Timothy E.; Ericson, M. Nance; Melechko, Anatoli V.; Simpson, Michael L.; Morrison, Barclay

    2012-01-01

    Neural chips, which are capable of simultaneous, multi-site neural recording and stimulation, have been used to detect and modulate neural activity for almost 30 years. As a neural interface, neural chips provide dynamic functional information for neural decoding and neural control. By improving sensitivity and spatial resolution, nano-scale electrodes may revolutionize neural detection and modulation at cellular and molecular levels as nano-neuron interfaces. We developed a carbon-nanofiber ...

  12. A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aibing, E-mail: chen_ab@163.com [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Liu, Chao [College of Gemmology and Material Technics, Shijiazhuang University of Economic, Huaian Road 136, Shijiazhuang 050031 (China); Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhang, Jian, E-mail: jzhang@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2014-07-15

    Highlights: • MCNFs were synthesized by a co-confined carbonization method. • The diameter size of MCNFs with bimodal mesoporous structure can be modulated. • The obtained MCNFs manifest better adsorption capacity for SO{sub 2}, CO{sub 2} and Cd{sup 2+}. - Abstract: Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80–120 nm possessed a bulk nitrogen content of 5.3 wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO{sub 2} and CO{sub 2}. Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO{sub 2} adsorption and 15 runs for CO{sub 2} adsorption. The MCNFs also have a preferable adsorption performance for Cd{sup 2+}.

  13. A reagentless enzymatic amperometric biosensor using vertically aligned carbon nanofibers (VACNF)

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, Martha L [University of Tennessee, Knoxville (UTK); Rahman, Touhidur [ORNL; Frymier, Paul Dexter [ORNL; Islam, Syed K [University of Tennessee, Knoxville (UTK); McKnight, Timothy E [ORNL

    2008-01-01

    A reagentless amperometric enzymatic biosensor is constructed on a carbon substrate for detection of ethanol. Yeast alcohol dehydrogenase (YADH), an oxidoreductase, and its cofactor nicotinamide adenine dinucleotide (NAD+) are immobilized by adsorption and covalent attachment to the carbon substrate. Carbon nanofibers grown by plasma enhanced chemical vapor deposition (PECVD) are chosen as the electrode material due to their excellent structural and electrical properties. Electrochemical techniques are employed to test the functionality and performance of the biosensor using reduced form of nicotinamide adenine dinucleotide (NADH) which also determines the oxidation peak potential of NADH. Subsequently, amperometric measurements are conducted for detection of ethanol to determine the electrical current response due to the increase in analyte concentration. The detection range, storage stability, reusability, and response time of the biosensor are also examined.

  14. Characterization and Alignment of Carbon Nanofibers under Shear Force in Microchannel

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    Jinshan Yang

    2016-01-01

    Full Text Available This work presents a novel method to align CNFs by using shear forces in microchannels. Effect of two different microchannel sizes (1 mm × 0.1 mm and 1 mm × 0.2 mm on CNFs alignment is investigated. SEM images of CNFs preform display significant alignment by both microchannels, which can be interpreted using a second-order alignment tensor and a manual angle meter. In the second-order alignment tensor description, an elongated ellipse can signify high degree of alignment in the direction of the major axis. When the microchannel size is 1 mm × 0.2 mm, the lengths of major and minor axes of the ellipse are 0.982 to 0.018. An angle meter manually shows that 85% of the CNFs are aligned in the direction between 60° and 90° when the microchannel is 1 mm × 0.2 mm. Both methods can demonstrate that better alignment of CNFs can be obtained using the 1 mm × 0.2 mm microchannel.

  15. Novel continuous carbon and ceramic nanofibers and nanocomposites

    Science.gov (United States)

    Wen, Yongkui

    2004-12-01

    Manufacturing of carbon nanofibers from PAN precursor is described in Chapter 2 of the dissertation. The electrospun nanofibers were continuous, uniform in diameter, and the samples didn't contain impurities, unlike carbon nanotubes or vapor grown carbon fibers. Systematic studies on the electrospinning parameters showed that nanofiber diameter could be varied in a range of 80 to 1800 nm. XRD studies on the carbon nanofibers fired at different temperatures showed that higher temperature resulted in better nanostructure. Fracture-free random carbon nanofiber sheets were produced by stretch-stabilization and carbonization for the first time. Toughening effects of random as-spun PAN, stabilized PAN, and carbon nanofibers on Mode I and Mode II interlaminar fracture of advanced carbon-epoxy composites were examined by DCB and ENF tests respectively in Chapter 3. The results showed that the interlaminar fracture toughness increased the most with carbon nanofiber reinforcement. 200% improvement in Mode I fracture toughness and 60% in Mode II fracture toughness were achieved with a minimum increase of weight. SEM fractographic analysis showed nanofiber pullout and crack bridging as the main nanomechanisms of toughening. Chapter 4 describes manufacturing of aligned carbon nanofibers and nanocomposites by a modified electrospinning technique. Constant-load stretch-stabilization was applied on carbon nanofibers for the first time. Analysis showed that mechanical properties of nanofibers and nanocomposites improved with stretch-stabilization and alignment of carbon nanofibers. Nanofabrication of ceramic 3Al2O3-2SiO2, SiO2-TiO2 nanofibers by a novel combination of sol-gel and electrospinning techniques invented recently at UNL is described in Chapters 5. The 3Al2O3-2SiO2, SiO2-TiO 2 nanofibers were continuous, non circular in cross section and had crystalline structure after high temperature calcination. Effects of the process parameters on their geometry and structure were

  16. Low-temperature self-assembled vertically aligned carbon nanofibers as counter-electrode material for dye-sensitized solar cells

    Science.gov (United States)

    Mahpeykar, S. M.; Tabatabaei, M. K.; Ghafoori-fard, H.; Habibiyan, H.; Koohsorkhi, J.

    2013-11-01

    Low-temperature AC-DC PECVD is employed for direct growth of vertically aligned carbon nanofibers (VACNFs) on ordinary transparent conductive glass as counter-electrode material for dye-sensitized solar cells (DSSCs). To the best of our knowledge, this is the first report on utilization of VACNFs grown directly on ordinary FTO-coated glass as a cost-effective catalyst material in DSSCs. According to the FESEM images, the as-grown arrays are well aligned and dense, and offer uniform coverage on the surface of the substrate. In-plane and out-of-plane conductivity measurements reveal their good electrical conductivity, and Raman spectroscopy suggests a high number of electrocatalytic active sites, favoring charge transport at the electrolyte/electrode interface. Hybrid VACNF/Pt electrodes are also fabricated for performance comparison with Pt and VACNF electrodes. X-ray diffraction results verify the crystallization of Pt in hybrid electrodes and further confirm the vertical alignment of carbon nanofibers. Electrochemical characterization indicates that VACNFs provide both high catalytic and good charge transfer capability, which can be attributed to their high surface area, defect-rich and one-dimensional structure, vertical alignment and low contact resistance. As a result, VACNF cells can achieve a comparable performance (˜5.6%) to that of the reference Pt cells (˜6.5%). Moreover, by combination of the excellent charge transport and catalytic ability of VACNFs and the high conductivity of Pt nanoparticles, hybrid VACNF/Pt cells can deliver a performance superior to that of the Pt cells (˜7.2%), despite having a much smaller amount of Pt loading, which raises hopes for low-cost large-scale production of DSSCs in the future.

  17. Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Pandey, Gaind P; Klankowski, Steven A; Li, Yonghui; Sun, Xiuzhi Susan; Wu, Judy; Rojeski, Ronald A; Li, Jun

    2015-09-23

    This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core-shell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g(-1) at C/10.5 (or 0.36 A g(-1)) rate and 1732 mAh g(-1) at 1C (or 3.8 A g(-1)) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core-shell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g(-1) at C/11 rate and ∼1070 mAh g(-1) at C/1.5 (or 2.6 A g(-1)) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge-discharge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.

  18. Enhanced thermal conductance of polymer composites through embeddingaligned carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Dale K. Hensley

    2016-07-01

    Full Text Available The focus of this work is to find a more efficient method of enhancing the thermal conductance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 μm and a higher thermal conductance between 25–40 μm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers.

  19. Processing and Structure of Carbon Nanofiber Paper

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    Zhongfu Zhao

    2009-01-01

    Full Text Available A unique concept of making nanocomposites from carbon nanofiber paper was explored in this study. The essential element of this method was to design and manufacture carbon nanofiber paper with well-controlled and optimized network structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under various processing conditions, including different types of carbon nanofibers, solvents, dispersants, and acid treatment. The morphologies of carbon nanofibers within the nanofiber paper were characterized with scanning electron microscopy (SEM. In addition, the bulk densities of carbon nanofiber papers were measured. It was found that the densities and network structures of carbon nanofiber paper correlated to the dispersion quality of carbon nanofibers within the paper, which was significantly affected by papermaking process conditions.

  20. Shear adhesion strength of aligned electrospun nanofibers.

    Science.gov (United States)

    Najem, Johnny F; Wong, Shing-Chung; Ji, Guang

    2014-09-01

    Inspiration from nature such as insects' foot hairs motivates scientists to fabricate nanoscale cylindrical solids that allow tens of millions of contact points per unit area with material substrates. In this paper, we present a simple yet robust method for fabricating directionally sensitive shear adhesive laminates. By using aligned electrospun nylon-6, we create dry adhesives, as a succession of our previous work on measuring adhesion energies between two single free-standing electrospun polymer fibers in cross-cylinder geometry, randomly oriented membranes and substrate, and peel forces between aligned fibers and substrate. The synthetic aligned cylindrical solids in this study are electrically insulating and show a maximal Mode II shear adhesion strength of 27 N/cm(2) on a glass slide. This measured value, for the purpose of comparison, is 270% of that reported from gecko feet. The Mode II shear adhesion strength, based on a commonly known "dead-weight" test, is 97-fold greater than the Mode I (normal) adhesion strength of the same. The data indicate a strong shear binding on and easy normal lifting off. Anisotropic adhesion (Mode II/Mode I) is pronounced. The size and surface boundary effects, crystallinity, and bending stiffness of fibers are used to understand these electrospun nanofibers, which vastly differ from otherwise known adhesive technologies. The anisotropic strength distribution is attributed to a decreasing fiber diameter and an optimized laminate thickness, which, in turn, influences the bending stiffness and solid-state "wettability" of points of contact between nanofibers and surface asperities.

  1. Low temperature and cost-effective growth of vertically aligned carbon nanofibers using spin-coated polymer-stabilized palladium nanocatalysts

    Science.gov (United States)

    Saleem, Amin M.; Shafiee, Sareh; Krasia-Christoforou, Theodora; Savva, Ioanna; Göransson, Gert; Desmaris, Vincent; Enoksson, Peter

    2015-02-01

    We describe a fast and cost-effective process for the growth of carbon nanofibers (CNFs) at a temperature compatible with complementary metal oxide semiconductor technology, using highly stable polymer-Pd nanohybrid colloidal solutions of palladium catalyst nanoparticles (NPs). Two polymer-Pd nanohybrids, namely poly(lauryl methacrylate)-block-poly((2-acetoacetoxy)ethyl methacrylate)/Pd (LauMAx-b-AEMAy/Pd) and polyvinylpyrrolidone/Pd were prepared in organic solvents and spin-coated onto silicon substrates. Subsequently, vertically aligned CNFs were grown on these NPs by plasma enhanced chemical vapor deposition at different temperatures. The electrical properties of the grown CNFs were evaluated using an electrochemical method, commonly used for the characterization of supercapacitors. The results show that the polymer-Pd nanohybrid solutions offer the optimum size range of palladium catalyst NPs enabling the growth of CNFs at temperatures as low as 350 °C. Furthermore, the CNFs grown at such a low temperature are vertically aligned similar to the CNFs grown at 550 °C. Finally the capacitive behavior of these CNFs was similar to that of the CNFs grown at high temperature assuring the same electrical properties thus enabling their usage in different applications such as on-chip capacitors, interconnects, thermal heat sink and energy storage solutions.

  2. Fabrication of aligned nanofibers by electric-field-controlled electrospinning: insulating-block method

    Science.gov (United States)

    Hwang, Wontae; Pang, Changhyun; Chae, Heeyeop

    2016-10-01

    Aligned nanofiber arrays and mats were fabricated with an electrospinning process by manipulating the electric field. The electric field was modified by insulating blocks (IBs) that were installed between the nozzle and the substrate as guiding elements to control the trajectory of the electrospinning jet flow. Simulation results showed that the electric field was deformed near the IBs, resulting in confinement of the electrospinning jet between the blocks. The balance of the electric field in the vertical direction and the repulsive force by space charges in the confined electrified jet stream was attributed to the aligned motion of the jet. Aligned arrays of 200 nm thick polyethylene oxide nanofibers were obtained, exhibiting wave-shaped and cross patterns as well as rectilinear patterns. In addition, 40 μm thick quasi-aligned carbon-nanofiber mats with anisotropic electrical property were also attained by this method.

  3. Electrospun nanofiber reinforcement of dental composites with electromagnetic alignment approach

    Energy Technology Data Exchange (ETDEWEB)

    Uyar, Tansel [Department of Biomedical Engineering, Başkent University Bağlıca Campus, 06530 Ankara (Turkey); Çökeliler, Dilek, E-mail: cokeliler@baskent.edu.tr [Department of Biomedical Engineering, Başkent University Bağlıca Campus, 06530 Ankara (Turkey); Doğan, Mustafa [Department of Electrical and Electronics Engineering, Başkent University, Ankara 06180 (Turkey); Koçum, Ismail Cengiz [Department of Biomedical Engineering, Başkent University Bağlıca Campus, 06530 Ankara (Turkey); Karatay, Okan [Department of Electrical and Electronics Engineering, Başkent University, Ankara 06180 (Turkey); Denkbaş, Emir Baki [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey)

    2016-05-01

    Polymethylmethacrylate (PMMA) is commonly used as a base acrylic denture material with benefits of rapid and easy handling, however, when it is used in prosthetic dentistry, fracturing or cracking problems can be seen due to the relatively low strength issues. Besides, acrylic resin is the still prominent material for denture fabrication due to its handy and low cost features. Numerous proposed fillers that are used to produce PMMA composites, however electrospun polyvinylalcohol (PVA) nanofiber fillers for production of PMMA composite resins are not studied as much as the others. The other focus of the practice is to compare both mechanical properties and efficiency of aligned fibers versus non-aligned PVA nanofibers in PMMA based dental composites. Field-controlled electrospinning system is manufactured and provided good alignment in lab scale as one of contributions. Some novel auxiliary electrodes in controlled structure are augmented to obtain different patterns of alignment with a certain range of fiber diameters. Scanning electron microscopy is used for physical characterization to determine the range of fiber diameters. Non-woven fiber has no unique pattern due to chaotic nature of electrospinning process, but aligned fibers have round pattern or crossed lines. These produced fibers are structured as layer-by-layer form with different features, and these features are used in producing PMMA dental composites with different volume ratios. The maximum flexural strength figure shows that fiber load by weight of 0.25% w/w and above improves in the maximum level. As a result, mechanical properties of PMMA dental composites are improved by using PVA nanofibers as a filler, however the improvement was higher when aligned PVA nanofibers are used. The maximum values were 5.1 MPa (flexural strength), 0.8 GPa (elastic modulus), and 170 kJ/m{sup 3} (toughness) in three-point bending test. In addition to the positive results of aligned and non-aligned nanofibers it was

  4. Uniaxially aligned ceramic nanofibers obtained by chemical mechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Tararam, R. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil); Foschini, C.R. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Bauru, Dept. de Eng. Mecanica, Av. Eng. Luiz Edmundo C. Coube 14-01, CEP 17033-360 Bauru, SP (Brazil); Destro, F.B. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Longo, E.; Varela, J.A. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil)

    2014-08-01

    For this study, we investigated a simple method to generate well aligned nanofibers over large areas using an organic polymer stretched over the substrate surface With this method, ZnO and CuO 3D parallel nanowire arrays were successfully prepared by calcinations of the polymer fibers. X-ray diffraction (XRD) analysis revealed that the copper oxide has a monoclinic structure while the zinc oxide has a hexagonal structure. Scanning electron microscopy (SEM) analysis showed ceramic nanofibers with an average diameter of 120 nm which were composed of small nanoparticles which are 10 nm in diameter. The ability to obtain uniaxially aligned nanofibers reveals a range of interesting properties with potential applications for sensors, catalysts and energy technologies.

  5. Growth of Y-shaped Carbon Nanofibers from Ethanol Flames

    Directory of Open Access Journals (Sweden)

    Cheng Jin

    2008-01-01

    Full Text Available Abstract Y-shaped carbon nanofibers as a multi-branched carbon nanostructure have potential applications in electronic devices. In this article, we report that several types of Y-shaped carbon nanofibers are obtained from ethanol flames. These Y-shaped carbon nanofibers have different morphologies. According to our experimental results, the growth mechanism of Y-shaped carbon nanofibers has been discussed and a possible growth model of Y-shaped carbon nanofibers has been proposed.

  6. Aligned Nanofibers for Regenerating Arteries, Nerves, and Muscles

    Science.gov (United States)

    McClendon, Mark Trosper

    Cells are the fundamental unit of the human body, and therefore the ability to control cell behavior is the most important challenge in regenerative medicine. Peptides are the language of biology which is why synthetic peptide amphiphile (PA) molecules hold great potential as a biomaterial. The work presented in this dissertation explores a variety of liquid crystalline PA nanofibers as a means for directing cell growth. Shaping the alignment of these nanofiber networks requires a deep understanding of their rheological properties which presents a difficult challenge as they exist in complex solid and liquid environments. Using PA molecules that self-assemble into high aspect ratio nanofibers and liquid crystalline solutions, this work investigates the influence of shear flow on macroscopic and microscopic nanofiber alignment. To this end, a shear force applied to PA solutions was systematically varied while the alignment was probed using small angle x-ray scattering. Nanofibers were found to respond to shear flow by aligning parallel to the flow direction. By changing pH and PA chemical sequence it was observed that increasing the interfiber electrostatic repulsive interactions resulted in a greater dependence on shear rate. Nanofiber solutions having greater repulsion did not drastically increase in alignment when the applied strain was increased by two orders of magnitude (1 s -1 to 100 s-1), while solutions with nanofibers having less repulsion increased there alignment four fold with the same strain increase. say exactly what you mean by resulted in greater dependence: did it result in fibers aligning under lower shear rates or higher rates--give the results Anionic PA solutions typically used to encapsulate living cells at neutral pH were found to require minimal shear rates, Bioluminescence and histology showed that stem cell engraftment into myofibers was greatly enhanced when delivered by PA gels compared to saline solution. The final section of this

  7. Highly Aligned Poly(vinylidene fluoride-co-hexafluoro propylene) Nanofibers via Electrospinning Technique.

    Science.gov (United States)

    Han, Tae-Hwan; Nirmala, R; Kim, Tae Woo; Navamathavan, R; Kim, Hak Yong; Park, Soo Jin

    2016-01-01

    We report on the simple way of obtaining aligned poly(vinylidiene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers by electrospinning process. The collector drum rotation speed was adjusted to prepare well aligned PVDF-HFP nanofibers. The degree of alignment and the orientation of PVDF-HFP nanofibers can be significantly altered by varying the speed of collector drum rotation. The resultant PVDF-HFP nanofibers were systematically characterized. From the scanning electron microscopy data, it was found that the electrospun PVDF-HFP nanofibers were formed with well-aligned nature. The X-ray diffraction results revealed that the electrospun PVDF-HFP nanofibers with β-phase can be formed by the increased collector drum rotation speed. Overall, the collector rotation speed during the electrospinning process plays an important role in obtaining well-aligned and improved characteristics of PVDF-HFP nanofibers.

  8. Fluorescent carbon nanowires made by pyrolysis of DNA nanofibers and plasmon-assisted emission enhancement of their fluorescence.

    Science.gov (United States)

    Nakao, Hidenobu; Tokonami, Shiho; Yamamoto, Yojiro; Shiigi, Hiroshi; Takeda, Yoshihiko

    2014-10-14

    We report on a facile method for preparing fluorescent carbon nanowires (CNWs) with pyrolysis of highly aligned DNA nanofibers as carbon sources. Silver nanoparticle (AgNP)-doped CNWs were also produced using pyrolysis of DNA nanofibers with well-attached AgNPs, indicating emission enhancement assisted by localized plasmon resonances.

  9. Carbon Nanofiber Nanoelectrodes for Biosensing Applications

    Science.gov (United States)

    Koehne, Jessica Erin

    2014-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  10. Carbon nanofibers: catalytic synthesis and applications

    NARCIS (Netherlands)

    Jong, K.P. de; Geus, John W.

    2001-01-01

    Carbon nanofibers (diameter range, 3-100 nm; length range, 1.1-1000 µm) have been known for a long time as a nuisance that often merges during catalythic conversion of carbon-containing gases. The recent outburst of interest in these graphitic materials originates from their potential for unique app

  11. Carbon nanofiber growth on thin rhodium layers

    NARCIS (Netherlands)

    Chinthaginjala, J.K.; Unnikrishnan, S.; Smithers, M.A.; Kip, G.A.M.; Lefferts, L.

    2012-01-01

    A thinlayer of carbon nanofibers (CNFs) was synthesized on a thin polycrystalline rhodium (Rh) metal layer by decomposing ethylene in the presence of hydrogen. Interaction of Rh crystals with carbon results in fragmentation and formation of Rh-nanoparticles, facilitating CNF growth. CNFs are immobil

  12. Precisely Assembled Nanofiber Arrays as a Platform to Engineer Aligned Cell Sheets for Biofabrication

    Directory of Open Access Journals (Sweden)

    Vince Beachley

    2014-08-01

    Full Text Available A hybrid cell sheet engineering approach was developed using ultra-thin nanofiber arrays to host the formation of composite nanofiber/cell sheets. It was found that confluent aligned cell sheets could grow on uniaxially-aligned and crisscrossed nanofiber arrays with extremely low fiber densities. The porosity of the nanofiber sheets was sufficient to allow aligned linear myotube formation from differentiated myoblasts on both sides of the nanofiber sheets, in spite of single-side cell seeding. The nanofiber content of the composite cell sheets is minimized to reduce the hindrance to cell migration, cell-cell contacts, mass transport, as well as the foreign body response or inflammatory response associated with the biomaterial. Even at extremely low densities, the nanofiber component significantly enhanced the stability and mechanical properties of the composite cell sheets. In addition, the aligned nanofiber arrays imparted excellent handling properties to the composite cell sheets, which allowed easy processing into more complex, thick 3D structures of higher hierarchy. Aligned nanofiber array-based composite cell sheet engineering combines several advantages of material-free cell sheet engineering and polymer scaffold-based cell sheet engineering; and it represents a new direction in aligned cell sheet engineering for a multitude of tissue engineering applications.

  13. Ellipsometric investigations of photonic crystals based on carbon nanofibers

    CERN Document Server

    Rehammar, R; Arwin, H; Kinaret, J M; Campbell, E E B

    2010-01-01

    Carbon nanofibers (CNF) are used as components of planar photonic crystals (PC). Square and rectangular lattices as well as random patterns of vertically aligned CNF were fabricated and their properties studied using ellipsometry. Conventional methods of ellipsometric analysis used in thin film ellipsometry are not applicable to these samples due to their nanostructured nature. We show that detailed information such as symmetry directions and the band structure of these novel materials can be extracted from considerations of the polarization state in the specular beam.

  14. Combined Cell Culture-Biosensing Platform Using Vertically Aligned Patterned Peptide Nanofibers for Cellular Studies

    DEFF Research Database (Denmark)

    Taskin, Mehmet B.; Sasso, Luigi; Dimaki, Maria

    2013-01-01

    This Article presents the development of a combined cell culture–biosensing platform using vertically aligned self-assembled peptide nanofibers. Peptide nanofibers were patterned on a microchip containing gold microelectrodes to provide the cells with a 3D environment enabling them to grow...

  15. Alignment and composition of laminin-polycaprolactone nanofiber blends enhance peripheral nerve regeneration.

    Science.gov (United States)

    Neal, Rebekah A; Tholpady, Sunil S; Foley, Patricia L; Swami, Nathan; Ogle, Roy C; Botchwey, Edward A

    2012-02-01

    Peripheral nerve transection occurs commonly in traumatic injury, causing deficits distal to the injury site. Conduits for repair currently on the market are hollow tubes; however, they often fail due to slow regeneration over long gaps. To facilitate increased regeneration speed and functional recovery, the ideal conduit should provide biochemically relevant signals and physical guidance cues, thus playing an active role in regeneration. To that end, laminin and laminin-polycaprolactone (PCL) blend nanofibers were fabricated to mimic peripheral nerve basement membrane. In vitro assays established 10% (wt) laminin content is sufficient to retain neurite-promoting effects of laminin. In addition, modified collector plate design to introduce an insulating gap enabled the fabrication of aligned nanofibers. The effects of laminin content and fiber orientation were evaluated in rat tibial nerve defect model. The lumens of conduits were filled with nanofiber meshes of varying laminin content and alignment to assess changes in motor and sensory recovery. Retrograde nerve conduction speed at 6 weeks was significantly faster in animals receiving aligned nanofiber conduits than in those receiving random nanofiber conduits. Animals receiving nanofiber-filled conduits showed some conduction in both anterograde and retrograde directions, whereas in animals receiving hollow conduits, no impulse conduction was detected. Aligned PCL nanofibers significantly improved motor function; aligned laminin blend nanofibers yielded the best sensory function recovery. In both cases, nanofiber-filled conduits resulted in better functional recovery than hollow conduits. These studies provide a firm foundation for the use of natural-synthetic blend electrospun nanofibers to enhance existing hollow nerve guidance conduits.

  16. Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Jong Won Choi

    2013-01-01

    Full Text Available This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT, graphene, and their hybrid structure under various operating conditions during a one-step synthesis via plasma-enhanced chemical vapor deposition (PECVD. We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

  17. Aligned Electrospun Polyvinyl Pyrrolidone/Poly ɛ-Caprolactone Blend Nanofiber Mats for Tissue Engineering

    Science.gov (United States)

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2016-02-01

    Electrospun nanofibrous materials are widely used in medical applications such as tissue engineering scaffolds, wound dressing material and drug delivery carriers. For tissue engineering scaffolds, the structure of the nanofiber is similar to extracellular matrix (ECM) which promotes the cell growth and proliferation. In the present study, the aligned nanofiber mats of polyvinyl pyrrolidone (PVP) blended poly ɛ-caprolactone (PCL) was successfully generated using electrospinning technique. The morphology of PVP/PCL nanofiber mats were characterized by scanning electron microspore (SEM). The chemical and crystalline structure of PVP/PCL nanofiber mats were analyzed using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffactometer (PXRD). The water contact angle of mats was investigated. Cell culture studies using normal human fibroblasts (NHF) were performed to assess cell morphology, cell alignment and cell proliferation. The results indicated that the fiber were in nanometer range. The PVP/PCL was well dispersed in nanofiber mats and was in amorphous form. The water contact angle of PVP/PCL nanofiber mats was lower than PCL nanofiber mats. The PVP/PCL nanofiber mats exhibited good biocompatibility with NHF cells. In summary, the PVP/PCL nanofiber mats had potential to be used in tissue engineering and regenerative medicine.

  18. Damping Augmentation of Nanocomposites Using Carbon Nanofiber Paper

    Directory of Open Access Journals (Sweden)

    Gangbing Song

    2006-06-01

    Full Text Available Vacuum-assisted resin transfer molding (VARTM process was used to fabricate the nanocomposites through integrating carbon nanofiber paper into traditional glass fiber reinforced composites. The carbon nanofiber paper had a porous structure with highly entangled carbon nanofibers and short glass fibers. In this study, the carbon nanofiber paper was employed as an interlayer and surface layer of composite laminates to enhance the damping properties. Experiments conducted using the nanocomposite beam indicated up to 200–700% increase of the damping ratios at higher frequencies. The scanning electron microscopy (SEM characterization of the carbon nanofiber paper and the nanocomposites was also conducted to investigate the impregnation of carbon nanofiber paper by the resin during the VARTM process and the mechanics of damping augmentation. The study showed a complete penetration of the resin through the carbon nanofiber paper. The connectivities between carbon nanofibers and short glass fibers within the carbon nanofiber paper were responsible for the significant energy dissipation in the nanocomposites during the damping tests.

  19. A new method for the alignment of electrospun nanofibers by oxygen plasma treatment

    Science.gov (United States)

    Kobayashi, Natsumi; Miki, Norihisa; Hishida, Koichi; Hotta, Atsushi

    2014-03-01

    An effective way of controlling the alignment of electrospun nanofibers using oxygen plasma treatment was introduced. Poly (dimethylsiloxane) (PDMS) was selected as a base material for electrospinning and polyvinyl alcohol (PVA) was chosen as an electrospun-nanofiber material. It was found that most of PVA nanofibers were selectively deposited on the O2 plasma-treated area of PDMS, while only a few PVA nanofibers were randomly deposited on the untreated area of the PDMS film. Interestingly, a number of PVA nanofibers were neatly aligned along the border of the untreated area and the O2 plasma-treated area of PDMS. The surface structures and the morphology of the PDMS films with PVA nanofibers were analyzed by scanning electron microscopy, water contact angle measurements, and X-ray photon spectroscopy. By selecting the optimized ratio of treated and untreated area of PDMS film, it was found that more than 80% of PVA nanofibers could be deposited parallel to the border of the treated and untreated area of PDMS. We used PVA as a reference material for the nanofiber alignment in this study, but similar deposition behavior was also observed for polyurethane (PU) fibers.

  20. The synthesis of titanium carbide-reinforced carbon nanofibers.

    Science.gov (United States)

    Zhu, Pinwen; Hong, Youliang; Liu, Bingbing; Zou, Guangtian

    2009-06-24

    Tailoring hard materials into nanoscale building blocks can greatly extend the applications of hard materials and, at the same time, also represents a significant challenge in the field of nanoscale science. This work reports a novel process for the preparation of carbon-based one-dimensional hard nanomaterials. The titanium carbide-carbon composite nanofibers with an average diameter of 90 nm are prepared by an electrospinning technique and a high temperature pyrolysis process. A composite solution containing polyacrylonitrile and titanium sources is first electrospun into the composite nanofibers, which are subsequently pyrolyzed to produce the desired products. The x-ray diffraction pattern and transmission electron microscopy results show that the main phase of the as-synthesized nanofibers is titanium carbide. The Raman analyses show that the composite nanofibers have low graphite clusters in comparison with the pure carbon nanofibers originating from the electrospun polyacrylonitrile nanofibers. The mechanical property tests demonstrate that the titanium carbide-carbon nanofiber membranes have four times higher tensile strength than the carbon nanofiber membranes, and the Young's modulus of the titanium carbide-carbon nanofiber membranes increases in direct proportion to the titanium quantity.

  1. Handspinning Enabled Highly Concentrated Carbon Nanotubes with Controlled Orientation in Nanofibers

    Science.gov (United States)

    Lee, Hoik; Watanabe, Kei; Kim, Myungwoong; Gopiraman, Mayakrishnan; Song, Kyung-Hun; Lee, Jung Soon; Kim, Ick Soo

    2016-11-01

    The novel method, handspinning (HS), was invented by mimicking commonly observed methods in our daily lives. The use of HS allows us to fabricate carbon nanotube-reinforced nanofibers (CNT-reinforced nanofibers) by addressing three significant challenges: (i) the difficulty of forming nanofibers at high concentrations of CNTs, (ii) aggregation of the CNTs, and (iii) control of the orientation of the CNTs. The handspun nanofibers showed better physical properties than fibers fabricated by conventional methods, such as electrospinning. Handspun nanofibers retain a larger amount of CNTs than electrospun nanofibers, and the CNTs are easily aligned uniaxially. We attributed these improvements provided by the HS process to simple mechanical stretching force, which allows for orienting the nanofillers along with the force direction without agglomeration, leading to increased contact area between the CNTs and the polymer matrix, thereby providing enhanced interactions. HS is a simple and straightforward method as it does not require an electric field, and, hence, any kinds of polymers and solvents can be applicable. Furthermore, it is feasible to retain a large amount of various nanofillers in the fibers to enhance their physical and chemical properties. Therefore, HS provides an effective pathway to create new types of reinforced nanofibers with outstanding properties.

  2. Vortex-Induced Alignment of a Water Soluble Supramolecular Nanofiber Composed of an Amphiphilic Dendrimer

    Directory of Open Access Journals (Sweden)

    Akihiko Tsuda

    2013-06-01

    Full Text Available We have synthesized a novel amphiphilic naphthalene imide bearing a cationic dendrimer wedge (NID. NID molecules in water self-assemble to form a two-dimensional ribbon, which further coils to give a linear supramolecular nanofiber. The sample solution showed linear dichroism (LD upon stirring of the solution, where NID nanofibers dominantly align at the center of vortex by hydrodynamic interaction with the downward torsional flows.

  3. Vortex-induced alignment of a water soluble supramolecular nanofiber composed of an amphiphilic dendrimer.

    Science.gov (United States)

    Yamamoto, Taiki; Tsuda, Akihiko

    2013-06-17

    We have synthesized a novel amphiphilic naphthalene imide bearing a cationic dendrimer wedge (NID). NID molecules in water self-assemble to form a two-dimensional ribbon, which further coils to give a linear supramolecular nanofiber. The sample solution showed linear dichroism (LD) upon stirring of the solution, where NID nanofibers dominantly align at the center of vortex by hydrodynamic interaction with the downward torsional flows.

  4. High performance carbon nanotube - polymer nanofiber hybrid fabrics

    Science.gov (United States)

    Yildiz, Ozkan; Stano, Kelly; Faraji, Shaghayegh; Stone, Corinne; Willis, Colin; Zhang, Xiangwu; Jur, Jesse S.; Bradford, Philip D.

    2015-10-01

    Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical conductivity. In order to further examine the hybrid fabric properties, they were consolidated under pressure, and also calendered at 70 °C. After calendering, the fabric's strength increased by an order of magnitude due to increased interactions and intermingling with the CNTs. The hybrids are highly efficient as aerosol filters; consolidated hybrid fabrics with a thickness of 20 microns and areal density of only 8 g m-2 exhibited ultra low particulate (ULPA) filter performance. The flexibility of this nanofabrication method allows for the use of many different polymer systems which provides the opportunity for engineering a wide range of nanoscale hybrid materials with desired functionalities.Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical

  5. Coaxially Aligned Polyaniline Nanofibers Doped with 3-Thiopheneacetic Acid through Interfacial Polymerization

    Directory of Open Access Journals (Sweden)

    Lixia Zhang

    2011-01-01

    Full Text Available Coaxially aligned polyaniline (PANI nanofibers doped with 3-thiopheneacetic acid (TAA were chemically synthesized by the interfacial polymerization of aniline in the presence of TAA, using iron (III chloride hexahydrate (FeCl3·6H2O as the oxidant. The morphology, crystallinity, room temperature conductivity, and coaxial alignment of the PANI-TAA nanofibers were highly dependent on the organic solvent used for the interfacial polymerization, the oxidant, and also the molar ratio of the aniline to TAA. Hexane, diethyl ether, dichloromethane, chloroform, and acetone were used as the organic solvents, and chloroform proved to be the best solvent for the formation of PANI-TAA nanofibers. The redox potential of the oxidant is the key to controlling the morphology and diameter of the PANI-TAA nanofibers. The use of FeCl3 as the oxidant leads to the formation of thin (∼50 nm PANI-TAA nanofibers, which increased in length, crystallinity, conductivity, and coaxial alignment as the molar ratio of TAA to aniline was increased from 0.1 : 1 to 1 : 1. By comparison, only granular PANI was obtained when ammonium persulfate (APS, which has a higher redox potential, was used as the oxidant. The doping function of TAA in the PANI-TAA nanofibers was confirmed by means of FTIR and UV-Visible spectroscopy.

  6. Effect of Carbon Nanofiber on Mechanical Behavior of Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Saeed Ghaffarpour Jahromi

    2015-09-01

    Full Text Available Uses of fibers to improve material properties have a scientific background in recent years in civil engineering. Use of Nanofiber reinforcement of materials refers to incorporating materials with desired properties within some other materials lacking those properties. Use of fibers for improvement is not a new phenomenon as the technique of fiber-reinforced bitumen began as early as 1950, but using nanofiber is a new idea. In this research the mechanical properties of asphalt mixture that have been modified with carbon nanofiber were investigated using mechanical tests, which can improve the performance of flexible pavements. To evaluate the effect of nanofiber contents on bituminous mixtures, laboratory investigations were carried out on the samples with and without nanofibers. During the course of this study, various tests were undertaken applying the Marshall test, indirect tensile test, resistance to fatigue cracking by using repeated load indirect tensile test and creep test. Carbon nanofiber exhibited consistency in results and it was observed that the addition of nanofiber can change the properties of bituminous mixtures, increase its stability and decrease the flow value. Results indicate that nanofiber have the potential to resist structural distress in the pavement and thus improve fatigue by increasing resistance to cracks or permanent deformation, when growing traffic loads. On the whole, the results show that the addition of carbon nanofiber will improve some of the mechanical properties such as fatigue and deformation in the flexible pavement.

  7. Microstructure transformation of carbon nanofibers during graphitization

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; TANG Yuan-hong; LIN Liang-wu; ZHANG En-lei

    2008-01-01

    The mierostructures of vapor-grown carbon nanofibers(CNFs) before and after graphitization process were analyzed by high resolution transmission electron microscopy(HRTEM), Raman spectroscopy, X-ray diffractometry(XRD), near-edge-X-ray absorption fine structure spectroscopy(NEXAFS) and thermogravimetric analysis(TGA). The results indicate that although non-graphitized CNFs have the characteristics of higher disorder, a transformation is found in the inner layer of tube wall where graphite sheets become stiff, which demonstrates the characteristics of higher graphitization of graphitized CNFs. The defects in outer tube wall disappear because the amorphous carbon changes to perfect crystalline carbon after annealing treatment at about 2 800 ℃. TGA analysis in air indicates that graphitized CNFs have excellent oxidation resistance up to 857 ℃. And the graphitization mechanism including four stages was also proposed.

  8. Improved Electrical Conductivity of Carbon/Polyvinyl Alcohol Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Nader Shehata

    2015-01-01

    Full Text Available Carbon nanofibers (CNFs gained much interest in the last few years due to their promising electrical, chemical, and mechanical characteristics. This paper investigates a new nanocomposite composed of carbon nanofibers hosted by PVA and both are integrated in one electrospun nanofibers web. This technique shows a simple and cheap way to offer a host for CNFs using traditional deposition techniques. The results show that electrical conductivity of the formed nanofibers has been improved up to 1.63 × 10−4 S/cm for CNFs of weight 2%. The peak temperature of mass loss through TGA measurements has been reduced by 2.3%. SEM images show the homogeneity of the formed PVA and carbon nanofibers in one web, with stretched CNFs after the electrospinning process. The formed nanocomposite can be used in wide variety of applications including nanoelectronics and gas adsorption.

  9. Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    LI Fu

    2016-11-01

    Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

  10. High performance carbon nanotube--polymer nanofiber hybrid fabrics.

    Science.gov (United States)

    Yildiz, Ozkan; Stano, Kelly; Faraji, Shaghayegh; Stone, Corinne; Willis, Colin; Zhang, Xiangwu; Jur, Jesse S; Bradford, Philip D

    2015-10-28

    Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical conductivity. In order to further examine the hybrid fabric properties, they were consolidated under pressure, and also calendered at 70 °C. After calendering, the fabric's strength increased by an order of magnitude due to increased interactions and intermingling with the CNTs. The hybrids are highly efficient as aerosol filters; consolidated hybrid fabrics with a thickness of 20 microns and areal density of only 8 g m(-2) exhibited ultra low particulate (ULPA) filter performance. The flexibility of this nanofabrication method allows for the use of many different polymer systems which provides the opportunity for engineering a wide range of nanoscale hybrid materials with desired functionalities.

  11. Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

    Science.gov (United States)

    Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

    2014-09-01

    Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration.

  12. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) proposes to develop a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. This anode...

  13. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) has successfully developed a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. PSI...

  14. Carbon nanofiber supercapacitors with large areal capacitances

    KAUST Repository

    McDonough, James R.

    2009-01-01

    We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/ cm2 and 1.2 F/ cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical. © 2009 American Institute of Physics.

  15. Superhydrophobic behavior of fluorinated carbon nanofiber arrays

    Science.gov (United States)

    Hsieh, Chien-Te; Fan, Wen-Syuan

    2006-06-01

    Superhydrophobic behavior of fluorinated carbon nanofiber (CNF) arrays, prepared by a template-assisted synthesis, has been investigated. A thermal chemical vapor method, using perfluorohexane as the precursor, was used to coat fluorocarbon on the surface of the CNFs, thus lowering their surface tension. The F-coated CNFs exhibited a good water-repellent behavior, i.e., the highest value of contact angle ˜166°. The superhydrophobicity of water droplets on the arrays can be well predicted by a modified Cassie-Baxter model, incorporating the pore size distributions determined from the density functional theory method. This satisfactory result would shed one light on how the variation of opened sizes would induce the superhydrophobicity of nanostructured surfaces.

  16. Uniaxially aligned electrospun all-cellulose nanocomposite nanofibers reinforced with cellulose nanocrystals: scaffold for tissue engineering.

    Science.gov (United States)

    He, Xu; Xiao, Qiang; Lu, Canhui; Wang, Yaru; Zhang, Xiaofang; Zhao, Jiangqi; Zhang, Wei; Zhang, Ximu; Deng, Yulin

    2014-02-10

    Uniaxially aligned cellulose nanofibers with well oriented cellulose nanocrystals (CNCs) embedded were fabricated via electrospinning using a rotating drum as the collector. Scanning electron microscope (SEM) images indicated that most cellulose nanofibers were uniaxially aligned. The incorporation of CNCs into the spinning dope resulted in more uniform morphology of the electrospun cellulose/CNCs nanocomposite nanofibers (ECCNN). Polarized light microscope (PLM) and transmission electron microscope (TEM) showed that CNCs dispersed well in ECCNN nonwovens and achieved considerable orientation along the long axis direction. This unique hierarchical microstructure of ECCNN nonwovens gave rise to remarkable enhancement of their physical properties. By incorporating 20% loading (in weight) of CNCs, the tensile strength and elastic modulus of ECCNN along the fiber alignment direction were increased by 101.7 and 171.6%, respectively. Their thermal stability was significantly improved as well. In addition, the ECCNN nonwovens were assessed as potential scaffold materials for tissue engineering. It was elucidated from MTT tests that the ECCNN were essentially nontoxic to human cells. Cell culture experiments demonstrated that cells could proliferate rapidly not only on the surface but also deep inside the ECCNN. More importantly, the aligned nanofibers of ECCNN exhibited a strong effect on directing cellular organization. This feature made the scaffold particularly useful for various artificial tissues or organs, such as blood vessel, tendon, nerve, and so on, in which cell orientation was crucial for their performance.

  17. Interfacial engineering of carbon nanofiber-graphene-carbon nanofiber heterojunctions in flexible lightweight electromagnetic shielding networks.

    Science.gov (United States)

    Song, Wei-Li; Wang, Jia; Fan, Li-Zhen; Li, Yong; Wang, Chan-Yuan; Cao, Mao-Sheng

    2014-07-09

    Lightweight carbon materials of effective electromagnetic interference (EMI) shielding have attracted increasing interest because of rapid development of smart communication devices. To meet the requirement in portable electronic devices, flexible shielding materials with ultrathin characteristic have been pursued for this purpose. In this work, we demonstrated a facile strategy for scalable fabrication of flexible all-carbon networks, where the insulting polymeric frames and interfaces have been well eliminated. Microscopically, a novel carbon nanofiber-graphene nanosheet-carbon nanofiber (CNF-GN-CNF) heterojunction, which plays the dominant role as the interfacial modifier, has been observed in the as-fabricated networks. With the presence of CNF-GN-CNF heterojunctions, the all-carbon networks exhibit much increased electrical properties, resulting in the great enhancement of EMI shielding performance. The related mechanism for engineering the CNF interfaces based on the CNF-GN-CNF heterojunctions has been discussed. Implication of the results suggests that the lightweight all-carbon networks, whose thickness and density are much smaller than other graphene/polymer composites, present more promising potential as thin shielding materials in flexible portable electronics.

  18. Improved fire retardancy of thermoset composites modified with carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Zhongfu Zhao and Jan Gou

    2009-01-01

    Full Text Available Multifunctional thermoset composites were made from polyester resin, glass fiber mats and carbon nanofiber sheets (CNS. Their flaming behavior was investigated with cone calorimeter under well-controlled combustion conditions. The heat release rate was lowered by pre-planting carbon nanofiber sheets on the sample surface with the total fiber content of only 0.38 wt.%. Electron microscopy showed that carbon nanofiber sheet was partly burned and charred materials were formed on the combusting surface. Both the nanofibers and charred materials acted as an excellent insulator and/or mass transport barrier, improving the fire retardancy of the composite. This behavior agrees well with the general mechanism of fire retardancy in various nanoparticle-thermoplastic composites.

  19. Template synthesis and magnetic properties of highly aligned barium hexaferrite (BaFe{sub 12}O{sub 19}) nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Boneng [College of Material Science and Engineering, Beijing Institute of Fashion Technology, Beijing 100029 (China); Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China); Li, Congju, E-mail: congjuli@gmail.com [College of Material Science and Engineering, Beijing Institute of Fashion Technology, Beijing 100029 (China); Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China); Wang, Jiaona [College of Material Science and Engineering, Beijing Institute of Fashion Technology, Beijing 100029 (China); Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China)

    2013-06-15

    Using electrospun poly(ethylene terephthalate)/citric acid (PET/CA) microfibers as the template, highly aligned barium hexaferrite (BaFe{sub 12}O{sub 19}) nanofibers with diameters of ca. 800 nm and lengths up to 2 cm were synthesized by sol–gel precursor coating technique and subsequent high temperature calcination. Structural and morphological investigations revealed that individual BaFe{sub 12}O{sub 19} nanofibers were composed of numerous nanocrystallites stacking alternatively along the nanofiber axis, the average grain size was ca. 225 nm and the single crystallites on each BaFe{sub 12}O{sub 19} nanofibers were of random orientations. The formation mechanism of aligned BaFe{sub 12}O{sub 19} nanofibers was proposed based on experiment. The magnetic measurement revealed that the aligned BaFe{sub 12}O{sub 19} nanofibers exhibited orientation-dependent magnetic behavior with respect to the applied magnetic field. The magnetic anisotropy with the easy magnetizing axis along the length of the nanofibers was due to the shape anisotropy. Such aligned magnetic nanofibers can find relevance in application requiring an orientation-dependent physical response. - Highlights: ► A simple method was used to synthesize the aligned BaFe{sub 12}O{sub 19} nanofibers. ► The aligned BaFe{sub 12}O{sub 19} nanofibers display an obvious orientation-dependent magnetic behavior. ► The method can be readily applied to other aligned one-dimensional inorganic nanomaterials.

  20. Spherical and rodlike inorganic nanoparticle regulated the orientation of carbon nanotubes in polymer nanofibers

    Science.gov (United States)

    Jiang, Linbin; Tu, Hu; Lu, Yuan; Wu, Yang; Tian, Jing; Shi, Xiaowen; Wang, Qun; Zhan, Yingfei; Huang, Zuqiang; Deng, Hongbing

    2016-04-01

    PVA nanofibers containing carboxylic-modified MWCNTs were fabricated via electrospinning of PVA/MWCNTs mixed solution. The alignment of MWCNTs in PVA nanofibers was studied using transmission electron microscope and scanning electron microscope. In addition, the orientation of MWCNTs in PVA nanofibers was further investigated in the presence of rod-like nanoparticle rectorite (REC) and of spherical nanoparticle titanium dioxide (TiO2). The images demonstrated the embedment of MWCNTs in the nanofibers and the alignment of MWCNTs along the fiber axis. Moreover, the addition of REC and TiO2 improved the alignment of MWCNTs in PVA nanofibers.

  1. Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

    Science.gov (United States)

    Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

    2016-12-01

    Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior.

  2. Uniaxially aligned electrospun cellulose acetate nanofibers for thin layer chromatographic screening of hydroquinone and retinoic acid adulterated in cosmetics.

    Science.gov (United States)

    Tidjarat, Siripran; Winotapun, Weerapath; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak

    2014-11-01

    Uniaxially aligned cellulose acetate (CA) nanofibers were successfully fabricated by electrospinning and applied to use as stationary phase for thin layer chromatography. The control of alignment was achieved by using a drum collector rotating at a high speed of 6000 rpm. Spin time of 6h was used to produce the fiber thickness of about 10 μm which was adequate for good separation. Without any chemical modification after the electrospinning process, CA nanofibers could be readily devised for screening hydroquinone (HQ) and retinoic acid (RA) adulterated in cosmetics using the mobile phase consisting of 65:35:2.5 methanol/water/acetic acid. It was found that the separation run on the aligned nanofibers over a distance of 5 cm took less than 15 min which was two to three times faster than that on the non-aligned ones. On the aligned nanofibers, the masses of HQ and RA which could be visualized were 10 and 25 ng, respectively, which were two times lower than those on the non-aligned CA fibers and five times lower than those on conventional silica plates due to the appearance of darker and sharper of spots on the aligned nanofibers. Furthermore, the proposed method efficiently resolved HQ from RA and ingredients commonly found in cosmetic creams. Due to the satisfactory analytical performance, facile and inexpensive production process, uniaxially aligned electrospun CA nanofibers are promising alternative media for planar chromatography.

  3. PREPARATION OF CARBON NANOFIBERS BY POLYMER BLEND TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The polymer blend technique is a novel method to produced carbon nanofibers. In this paper, we have prepared fine carbon fibers and porous carbon materials by this technique, and we will discuss the experiment results by means of SEM, TGA, Element Analysis, etc.

  4. Engineering hybrid polymer-protein super-aligned nanofibers via rotary jet spinning.

    Science.gov (United States)

    Badrossamay, Mohammad R; Balachandran, Kartik; Capulli, Andrew K; Golecki, Holly M; Agarwal, Ashutosh; Goss, Josue A; Kim, Hansu; Shin, Kwanwoo; Parker, Kevin Kit

    2014-03-01

    Cellular microenvironments are important in coaxing cells to behave collectively as functional, structured tissues. Important cues in this microenvironment are the chemical, mechanical and spatial arrangement of the supporting matrix in the extracellular space. In engineered tissues, synthetic scaffolding provides many of these microenvironmental cues. Key requirements are that synthetic scaffolds should recapitulate the native three-dimensional (3D) hierarchical fibrillar structure, possess biomimetic surface properties and demonstrate mechanical integrity, and in some tissues, anisotropy. Electrospinning is a popular technique used to fabricate anisotropic nanofiber scaffolds. However, it suffers from relatively low production rates and poor control of fiber alignment without substantial modifications to the fiber collector mechanism. Additionally, many biomaterials are not amenable for fabrication via high-voltage electrospinning methods. Hence, we reasoned that we could utilize rotary jet spinning (RJS) to fabricate highly aligned hybrid protein-polymer with tunable chemical and physical properties. In this study, we engineered highly aligned nanofiber constructs with robust fiber alignment from blends of the proteins collagen and gelatin, and the polymer poly-ε-caprolactone via RJS and electrospinning. RJS-spun fibers retain greater protein content on the surface and are also fabricated at a higher production rate compared to those fabricated via electrospinning. We measured increased fiber diameter and viscosity, and decreasing fiber alignment as protein content increased in RJS hybrid fibers. RJS nanofiber constructs also demonstrate highly anisotropic mechanical properties mimicking several biological tissue types. We demonstrate the bio-functionality of RJS scaffold fibers by testing their ability to support cell growth and maturation with a variety of cell types. Our highly anisotropic RJS fibers are therefore able to support cellular alignment

  5. CHARACTERIZATION AND ADSORPTION PROPERTIES OF POROUS CARBON NANOFIBER GRANULES

    Institute of Scientific and Technical Information of China (English)

    Jiuling Chen; Qinghai Chen; Yongdan Li

    2006-01-01

    The properties of the porous granules produced by agglomeration of catalytically grown carbon nanofibers were investigated in this work. The single pellet crushing strength of the granules is high, e.g., 1.6-2.5 MPa. They have adsorption at 298 K of benzene or phenol on the granules is much lower than that on activated carbon and depends not only on the specific surface area of the carbon material but also on the sewing structure of the granules and the morphology of the carbon nanofibers. Treatment in dilute nitric acid appreciably reduces such adsorption.

  6. Extraordinary improvement of the graphitic structure of continuous carbon nanofibers templated with double wall carbon nanotubes.

    Science.gov (United States)

    Papkov, Dimitry; Beese, Allison M; Goponenko, Alexander; Zou, Yan; Naraghi, Mohammad; Espinosa, Horacio D; Saha, Biswajit; Schatz, George C; Moravsky, Alexander; Loutfy, Raouf; Nguyen, Sonbinh T; Dzenis, Yuris

    2013-01-22

    Carbon nanotubes are being widely studied as a reinforcing element in high-performance composites and fibers at high volume fractions. However, problems with nanotube processing, alignment, and non-optimal stress transfer between the nanotubes and surrounding matrix have so far prevented full utilization of their superb mechanical properties in composites. Here, we present an alternative use of carbon nanotubes, at a very small concentration, as a templating agent for the formation of graphitic structure in fibers. Continuous carbon nanofibers (CNF) were manufactured by electrospinning from polyacrylonitrile (PAN) with 1.2% of double wall nanotubes (DWNT). Nanofibers were oxidized and carbonized at temperatures from 600 °C to 1850 °C. Structural analyses revealed significant improvements in graphitic structure and crystal orientation in the templated CNFs, with the largest improvements observed at lower carbonization temperatures. In situ pull-out experiments showed good interfacial bonding between the DWNT bundles and the surrounding templated carbon matrix. Molecular Dynamics (MD) simulations of templated carbonization confirmed oriented graphitic growth and provided insight into mechanisms of carbonization initiation. The obtained results indicate that global templating of the graphitic structure in fine CNFs can be achieved at very small concentrations of well-dispersed DWNTs. The outcomes reveal a simple and inexpensive route to manufacture continuous CNFs with improved structure and properties for a variety of mechanical and functional applications. The demonstrated improvement of graphitic order at low carbonization temperatures in the absence of stretch shows potential as a promising new manufacturing technology for next generation carbon fibers.

  7. CONFORMATION AND MICROSTRUCTURE OF CARBON NANOFIBERS DEPOSITED ON FOAM Ni

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Bundles of pure carbon nanofibers were prepared by catalytic decomposition of acetylene on foam Ni. The morphological and structural characteristics of the carbon nanostructures, in the as-prepared state, were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HTEM). A special conformation of carbon nanofibers composed of segmented structures was found among the products by both SEM and TEM observations. Further HTEM ex amination indicated that the segments were stacked with well ordered graphite platelets arranged perpendicular to the axis of the filaments.

  8. Radiation Effects on Polypropylene Carbon Nanofibers

    Science.gov (United States)

    Hamilton, John; Mion, Thomas; Chipara, Alin C.; Ibrahim, Elamin I.; Lozano, Karen; Chipara, Magdalena; Tidrow, Steven C.; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects most physical and chemical properties of the polymeric matrix (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Such changes have been reported and explained by thorough spectroscopic investigations. Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF)composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA) and by US Army Research Office (AMSRD-ARL-RO-SI: 54498-MS-ISP).

  9. Label-Free Detection of Cardiac Troponin-I Using Carbon Nanofiber Based Nanoelectrode Arrays

    Science.gov (United States)

    Periyakaruppan, Adaikkappan; Koehne, Jessica Erin; Gandhiraman, Ram P.; Meyyappan, M.

    2013-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. A carbon nanofiber (CNF) multiplexed array has been fabricated with 9 sensing pads, each containing 40,000 carbon nanofibers as nanoelectrodes. Here, we report the use of vertically aligned CNF nanoelectrodes for the detection of cardiac Troponin-I for the early diagnosis of myocardial infarction. Antibody, antitroponin, probe immobilization and subsequent binding to human cardiac troponin-I were characterized using electrochemical impedance spectroscopy and cyclic voltammetry techniques. Each step of the modification process resulted in changes in electrical capacitance or resistance to charge transfer due to the changes at the electrode surface upon antibody immobilization and binding to the specific antigen. This sensor demonstrates high sensitivity, down to 0.2 ng/mL, and good selectivity making this platform a good candidate for early stage diagnosis of myocardial infarction.

  10. Process optimization and empirical modeling for electrospun polyacrylonitrile (PAN) nanofiber precursor of carbon nanofibers

    NARCIS (Netherlands)

    Gu, S.Y.; Ren, J.; Vancso, G.J.

    2005-01-01

    Ultrafine fibers were spun from polyacrylonitrile (PAN)/N,N-dimethyl formamide (DMF) solution as a precursor of carbon nanofibers using a homemade electrospinning set-up. Fibers with diameter ranging from 200 nm to 1200 nm were obtained. Morphology of fibers and distribution of fiber diameter were i

  11. Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films

    Science.gov (United States)

    Sun, Luyi; O'Reilly, Jonathan Y.; Tien, Chi-Wei; Sue, Hung-Jue

    2008-01-01

    A simple and effective approach to prepare conductive polystyrene/carbon nanofiber (PS/CNF) nanocomposite films via a solution dispersion method is presented. Inexpensive CNF, which has a structure similar to multi-walled carbon nanotubes, is chosen as a nanofiller in this experiment to achieve conductivity in PS films. A good dispersion is…

  12. Synthesis of Carbon Nanofibers on Large Woven Cloth

    NARCIS (Netherlands)

    Kotanjac, Z.; Lefferts, L.; Koissin, V.; Warnet, L.; Akkerman, R.

    2015-01-01

    This experimental study aims at the in situ growth of carbon nano-fibers (CNFs) on relatively large (25 × 30 cm2) single-layer carbon-fiber fabrics. It is shown that CNFs can be grown with the distribution potentially suitable for a future use in polymer-matrix composite materials. Details of tuning

  13. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    NARCIS (Netherlands)

    Manea, F.; Motoc, S.; Pop, A.; Remes, A.; Schoonman, J.

    2012-01-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nan

  14. Conductive Behaviors of Carbon Nanofibers Reinforced Epoxy Composites

    Institute of Scientific and Technical Information of China (English)

    MEI Qilin; WANG Jihui; WANG Fuling; HUANG Zhixiong; YANG Xiaolin; WEI Tao

    2008-01-01

    By means of ultrasonic dispersion,carbon nanofibers reinforced epoxy resin composite was prepared in the lab,the electrical conductivity of composite with different carbon nanofibers loadings were studied,also the voltage-current relationship,resistance-temperature properties and mechano-electric effect were investigated.Results show that the resistivity of composite decreases in geometric progression with the increasing of carbon nanofibers,and the threshold ranges between 0.1 wt%-0.2 wt%.The voltage-current relationship is in good conformity with the Ohm's law,both positive temperature coefficient and negative temperature coefficient can be found at elevated temperature.In the course of stretching,the electrical resistance of the composites increases with the stress steadily and changes sharply near the breaking point,which is of importance for the safety monitor and structure health diagnosis.

  15. Aligned carbon nanotubes for nanoelectronics

    Science.gov (United States)

    Choi, Won Bong; Bae, Eunju; Kang, Donghun; Chae, Soodoo; Cheong, Byung-ho; Ko, Ju-hye; Lee, Eungmin; Park, Wanjun

    2004-10-01

    We discuss the central issues to be addressed for realizing carbon nanotube (CNT) nanoelectronics. We focus on selective growth, electron energy bandgap engineering and device integration. We have introduced a nanotemplate to control the selective growth, length and diameter of CNTs. Vertically aligned CNTs are synthesized for developing a vertical CNT-field effect transistor (FET). The ohmic contact of the CNT/metal interface is formed by rapid thermal annealing. Diameter control, synthesis of Y-shaped CNTs and surface modification of CNTs open up the possibility for energy bandgap modulation. The concepts of an ultra-high density transistor based on the vertical-CNT array and a nonvolatile memory based on the top gate structure with an oxide-nitride-oxide charge trap are also presented. We suggest that the deposited memory film can be used for the quantum dot storage due to the localized electric field created by a nano scale CNT-electron channel.

  16. High-throughput and high-yield fabrication of uniaxially-aligned chitosan-based nanofibers by centrifugal electrospinning.

    Science.gov (United States)

    Erickson, Ariane E; Edmondson, Dennis; Chang, Fei-Chien; Wood, Dave; Gong, Alex; Levengood, Sheeny Lan; Zhang, Miqin

    2015-12-10

    The inability to produce large quantities of nanofibers has been a primary obstacle in advancement and commercialization of electrospinning technologies, especially when aligned nanofibers are desired. Here, we present a high-throughput centrifugal electrospinning (HTP-CES) system capable of producing a large number of highly-aligned nanofiber samples with high-yield and tunable diameters. The versatility of the design was revealed when bead-less nanofibers were produced from copolymer chitosan/polycaprolactone (C-PCL) solutions despite variations in polymer blend composition or spinneret needle gauge. Compared to conventional electrospinning techniques, fibers spun with the HTP-CES not only exhibited superior alignment, but also better diameter uniformity. Nanofiber alignment was quantified using Fast Fourier Transform (FFT) analysis. In addition, a concave correlation between the needle diameter and resultant fiber diameter was identified. This system can be easily scaled up for industrial production of highly-aligned nanofibers with tunable diameters that can potentially meet the requirements for various engineering and biomedical applications.

  17. Non-lithographic organization of nickel catalyst for carbon nanofiber synthesis on laser-induced periodic surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Y F [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2200 (United States); Melechko, A V [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Pedraza, A J [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2200 (United States); Simpson, M L [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2200 (United States); Rack, P D [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996-2200 (United States)

    2007-08-22

    We present a non-lithographic technique that produces organized nanoscale nickel catalyst for carbon nanofiber growth on a silicon substrate. This technique involves three consecutive steps: first, the substrate is laser-irradiated to produce a periodic nanorippled structure; second, a thin film of nickel is deposited using glancing-angle ion-beam sputter deposition, followed by heat treatment, and third, a catalytic dc plasma-enhanced chemical vapor deposition (PECVD) process is conducted to produce the vertically aligned carbon nanofibers (VACNF). The nickel catalyst is distributed along the laser-induced periodic surface structure (LIPSS) and the Ni particle dimension varies as a function of the location on the LIPSS and is correlated to the nanoripple dimensions. The glancing angle, the distance between the ion beam collimators and the total deposition time all play important roles in determining the final catalyst size and subsequent carbon nanofiber properties. Due to the gradual aspect ratio change of the nanoripples across the sample, Ni catalyst nanoparticles of different dimensions were obtained. After the prescribed three minute PECVD growth, it was observed that, in order for the carbon nanofibers to survive, the nickel catalyst dimension should be larger than a critical value of {approx}19 nm, below which the Ni is insufficient to sustain carbon nanofiber growth.

  18. Shear induced alignment of short nanofibers in 3D printed polymer composites

    Science.gov (United States)

    Erdem Yunus, Doruk; Shi, Wentao; Sohrabi, Salman; Liu, Yaling

    2016-12-01

    3D printing of composite materials offers an opportunity to combine the desired properties of composite materials with the flexibility of additive manufacturing in geometric shape and complexity. In this paper, the shear-induced alignment of aluminum oxide nanowires during stereolithography printing was utilized to fabricate a nanowire reinforced polymer composite. To align the fibers, a lateral oscillation mechanism was implemented and combined with wall pattern printing technique to generate shear flow in both vertical and horizontal directions. A series of specimens were fabricated for testing the composite material’s tensile strength. The results showed that mechanical properties of the composite were improved by reinforcement of nanofibers through shear induced alignment. The improvement of tensile strength was approximately ∼28% by aligning the nanowires at 5 wt% (∼1.5% volume fraction) loading of aluminum oxide nanowires.

  19. Shear induced alignment of short nanofibers in 3D printed polymer composites.

    Science.gov (United States)

    Yunus, Doruk Erdem; Shi, Wentao; Sohrabi, Salman; Liu, Yaling

    2016-12-09

    3D printing of composite materials offers an opportunity to combine the desired properties of composite materials with the flexibility of additive manufacturing in geometric shape and complexity. In this paper, the shear-induced alignment of aluminum oxide nanowires during stereolithography printing was utilized to fabricate a nanowire reinforced polymer composite. To align the fibers, a lateral oscillation mechanism was implemented and combined with wall pattern printing technique to generate shear flow in both vertical and horizontal directions. A series of specimens were fabricated for testing the composite material's tensile strength. The results showed that mechanical properties of the composite were improved by reinforcement of nanofibers through shear induced alignment. The improvement of tensile strength was approximately ∼28% by aligning the nanowires at 5 wt% (∼1.5% volume fraction) loading of aluminum oxide nanowires.

  20. Non-continuum, anisotropic nanomechanics of random and aligned electrospun nanofiber matrices

    Science.gov (United States)

    Chery, Daphney; Han, Biao; Mauck, Robert; Shenoy, Vivek; Han, Lin

    Polymer nanofiber assemblies are widely used in cell culture and tissue engineering, while their nanomechanical characteristics have received little attention. In this study, to understand their nanoscale structure-mechanics relations, nanofibers of polycaprolactone (PCL) and poly(vinyl alcohol) (PVA) were fabricated via electrospinning, and tested via AFM-nanoindentation with a microspherical tip (R ~10 μm) in PBS. For the hydrophobic, less-swollen PCL, a novel, non-continuum linear F-D dependence was observed, instead of the typical Hertzian F-D3/2 behavior, which is usually expected for continuum materials. This linear trend is likely resulted from the tensile stretch of a few individual nanofibers as they were indented in the normal plane. In contrast, for the hydrophilic, highly swollen PVA, the observed typical Hertzian response indicates the dominance of localized deformation within each nanofiber, which had swollen to become hydrogels. Furthermore, for both matrices, aligned fibers showed significantly higher stiffness than random fibers. These results provide a fundamental basis on the nanomechanics of biomaterials for specialized applications in cell phenotype and tissue repair.

  1. Aligned PVDF-TrFE nanofibers with high-density PVDF nanofibers and PVDF core–shell structures for endovascular pressure sensing.

    Science.gov (United States)

    Sharma, Tushar; Naik, Sahil; Langevine, Jewel; Gill, Brijesh; Zhang, John X J

    2015-01-01

    Nanostructures of polyvinyledenedifluoride-tetrafluoroethylene (PVDF-TrFE), a semicrystalline polymer with high piezoelectricity, results in significant enhancement of crystallinity and better device performance as sensors, actuators, and energy harvesters. Using electrospinning of PVDF to manufacture nanofibers, we demonstrate a new method to pattern high-density, highly aligned nanofibers. To further boost the charge transfer from such a bundle of nanofibers, we fabricated novel core-shell structures. Finally, we developed pressure sensors utilizing these fiber structures for endovascular applications. The sensors were tested in vitro under simulated physiological conditions. We observed significant improvements using core-shell electrospun fibers (4.5 times gain in signal intensity, 4000 μV/mmHg sensitivity) over PVDF nanofibers (280 μV/mmHg). The preliminary results showed that core-shell fiber-based devices exhibit nearly 40-fold higher sensitivity, compared to the thin-film structures demonstrated earlier.

  2. Enhancement of Ultrahigh Performance Concrete Material Properties with Carbon Nanofiber

    Directory of Open Access Journals (Sweden)

    Libya Ahmed Sbia

    2014-01-01

    Full Text Available Ultrahigh performance concrete (UHPC realized distinctly high mechanical, impermeability, and durability characteristics by reducing the size and content of capillary pore, refining the microstructure of cement hydrates, and effectively using fiber reinforcement. The dense and fine microstructure of UHPC favor its potential to effectively disperse and interact with nanomaterials, which could complement the reinforcing action of fibers in UHPC. An optimization experimental program was implemented in order to identify the optimum combination of steel fiber and relatively low-cost carbon nanofiber in UHPC. The optimum volume fractions of steel fiber and carbon nanofiber identified for balanced improvement of flexural strength, ductility, energy sorption capacity, impact, and abrasion resistance of UHPC were 1.1% and 0.04%, respectively. Desired complementary/synergistic actions of nanofibers and steel fibers in UHPC were detected, which were attributed to their reinforcing effects at different scales, and the potential benefits of nanofibers to interfacial bonding and pull-out behavior of fibers in UHPC. Modification techniques which enhanced the hydrophilicity and bonding potential of nanofibers to cement hydrates benefited their reinforcement efficiency in UHPC.

  3. Structure and properties of carbon nanofibers. application as electrocatalyst support

    Directory of Open Access Journals (Sweden)

    S. del Rio

    2012-03-01

    Full Text Available The present work aimed to gain an insight into the physical-chemical properties of carbon nanofibers and the relationship between those properties and the electrocatalytic behavior when used as catalyst support for their application in fuel cells.

  4. Synthesis of porous carbon nanofiber with bamboo-like carbon nanofiber branches by one-step carbonization process

    Science.gov (United States)

    Yoo, Seung Hwa; Joh, Han-Ik; Lee, Sungho

    2017-04-01

    Porous carbon nanofibers (PCNFs) with CNF branches (PCNF/bCNF) were synthesized by a simple heat treatment method. Conventional methods to synthesize this unique structure usually follow a typical route, which consists of CNF preparation, catalyst deposition, and secondary CNF growth. In contrast, our method utilized a one-step carbonization process of polymer nanofibers, which were electrospun from a one-pot solution consisted of polyacrylonitrile, polystyrene (PS), and iron acetylacetonate. Various structures of PCNF/CNF were synthesized by changing the solution composition and molecular weight of PS. It was verified that the content and molecular weight of PS were critical for the growth of catalyst particles and subsequent growth of CNF branches. The morphology, phase of catalyst, and carbon structure of PCNF/bCNF were analyzed at different temperature steps during carbonization. It was found that pores were generated by the evaporation of PS and the catalyst particles were formed on the surface of PCNF at 700 °C. The gases originated from the evaporation of PS acted as a carbon source for the growth of CNF branches that started at 900 °C. Finally, when the carbonization process was finished at 1200 °C, uniform and abundant CNF branches were formed on the surface of PCNF.

  5. Surface functionalization of carbon nanofibers by sol-gel coating of zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Shao Dongfeng [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China); Changzhou Textile Garment Institute, Changzhou 213164 (China); Wei Qufu [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)], E-mail: qfwei@jiangnan.edu.cn; Zhang Liwei; Cai Yibing; Jiang Shudong [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)

    2008-08-15

    In this paper the functional carbon nanofibers were prepared by the carbonization of ZnO coated PAN nanofibers to expand the potential applications of carbon nanofibers. Polyacrylonitrile (PAN) nanofibers were obtained by electrospinning. The electrospun PAN nanofibers were then used as substrates for depositing the functional layer of zinc oxide (ZnO) on the PAN nanofiber surfaces by sol-gel technique. The effects of coating, pre-oxidation and carbonization on the surface morphology and structures of the nanofibers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM), respectively. The results of SEM showed a significant increase of the size of ZnO nanograins on the surface of nanofibers after the treatments of coating, pre-oxidation and carbonization. The observations by SEM also revealed that ZnO nanoclusters were firmly and clearly distributed on the surface of the carbon nanofibers. FTIR examination also confirmed the deposition of ZnO on the surface of carbon nanofibers. The XRD analysis indicated that the crystal structure of ZnO nanograins on the surface of carbon nanofibers.

  6. Electrochemical characteristics of activated carbon nanofiber electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Min-Kang [Dept. of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin [Dept. of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of)], E-mail: sjpark@inha.ac.kr

    2009-08-25

    In this work, poly(amide imide) solutions in dimethylformamide were electrospun into webs consisting of 350 nm ultrafine nanofibers. These nanofiber webs were used to produce activated carbon nanofibers (ACNFs), through stabilization and carbonisation-activation processes. Experimental results indicated that ACNFs activated at 800 deg. C afforded the highest specific surface area but low mesopore volume. The high specific surface area, mainly due to the micropores, introduced maximum specific capacitance at low current density (150 F g{sup -1} at 10 mA g{sup -1}). Elevating the volume fraction of mesopores gave maximum specific capacitance at high current density (100 F g{sup -1} at 1000 mA g{sup -1}), which could be explained on the basis of ion mobility in the pores. Thus, the capacitance of the supercapacitors was strongly dependent on the specific surface area and micro- or mesopore volume of the ACNFs.

  7. Synthesis and Electrochemical Properties of Carbon Nanofibers and SiO2/Carbon Nanofiber Composite on Ni-Cu/C-Fiber Textiles.

    Science.gov (United States)

    Nam, Ki-Mok; Park, Heai-Ku; Lee, Chang-Seop

    2015-11-01

    In this study, carbon nanofibers (CNFs) were grown by chemical vapor deposition on C-fiber textiles that had Ni and Cu catalyst deposited via electrophoretic deposition. Before the CNFs were coated with silica layer via hydrolysis of TEOS (Tetraethyl orthosilicate), the carbon nanofibers were oxidized by nitric acid. Due to oxidation, the hydroxyl group was created on the carbon nanofibers and this was used as an activation site for the SiO2. The physicochemical properties of the grown carbon nanofibers were investigated with Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The structures of SiO2-coated carbon nanofibers were characterized by XPS and TEM. The electrochemical properties and the capacitance of the materials were investigated by galvanostatic charge-discharge and cyclic voltammetry. Different types of carbon nanofibers were grown upon the deposition utilizing catalysts, with the SiO2 uniformly coated on the surface of carbon nanofibers. When used as an anode material for the Li secondary battery, the SiO2/CNFs composite had a lower capacity maintenance and a greater discharge capacity as compared to the carbon nanofibers.

  8. Carbon Nanofibers (CNFs) Surface Modification to Fabricate Carbon Nanofibers_Nanopaper Integrated Polymer Composite Material.

    Science.gov (United States)

    Jiang, Jianjun; Zhao, Ziwei; Deng, Chao; Liu, Fa; Li, Dejia; Fang, Liangchao; Zhang, Dan; Castro Jose M; Chen, Feng; Lee, L James

    2016-06-01

    Carbon Nanofibers (CNFs) have shown great potential to improve the physical and mechanical properties of conventional Fiber Reinforced Polymer Composites (FRPCs) surface. Excellent dispersion CNFs into water or polymer matrix was very crucial to get good quality CNFs enhanced FRPCs. Because of the hydrophobic properties of CNFs, we apply the reversible switching principles to transfer the hydrophobic surface into hydrophilic surface by growing polyaniline nanograss on the surface of CNFs which was carried out in hydrochloric acid condition. Incorporating CNFs into FRPCs as a surface layer named CNFs Nanopaper to increase the erosion resistance and electrical conductivity in this research which was very important in the wind energy field. In order to get high quality dispersed CNFs suspension, a sonication unit was used to detangle and uniform disperse the functionalized CNFs. A filter with vacuum pressure used to filter the suspension of CNFs onto Carbon veil to make CNFs Nanopaper. Vacuum Aided Resin Transfer Modeling (VARTM) process was used to fabricate Nano-enhanced FRPCs samples. In order to characterize the mechanical properties, three point bending experiment was measured. The flexural strength capacity and deformation resistance and behavior were compared and analyzed. In this paper, we discussed the methods used and provided experimental parameter and experimental results.

  9. Activated Carbon, Carbon Nanofiber and Carbon Nanotube Supported Molybdenum Carbide Catalysts for the Hydrodeoxygenation of Guaiacol

    Directory of Open Access Journals (Sweden)

    Eduardo Santillan-Jimenez

    2015-03-01

    Full Text Available Molybdenum carbide was supported on three types of carbon support—activated carbon; multi-walled carbon nanotubes; and carbon nanofibers—using ammonium molybdate and molybdic acid as Mo precursors. The use of activated carbon as support afforded an X-ray amorphous Mo phase, whereas crystalline molybdenum carbide phases were obtained on carbon nanofibers and, in some cases, on carbon nanotubes. When the resulting catalysts were tested in the hydrodeoxygenation (HDO of guaiacol in dodecane, catechol and phenol were obtained as the main products, although in some instances significant amounts of cyclohexane were produced. The observation of catechol in all reaction mixtures suggests that guaiacol was converted into phenol via sequential demethylation and HDO, although the simultaneous occurrence of a direct demethoxylation pathway cannot be discounted. Catalysts based on carbon nanofibers generally afforded the highest yields of phenol; notably, the only crystalline phase detected in these samples was Mo2C or Mo2C-ζ, suggesting that crystalline Mo2C is particularly selective to phenol. At 350 °C, carbon nanofiber supported Mo2C afforded near quantitative guaiacol conversion, the selectivity to phenol approaching 50%. When guaiacol HDO was performed in the presence of acetic acid and furfural, guaiacol conversion decreased, although the selectivity to both catechol and phenol was increased.

  10. Carbon nanofiber growth in plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Denysenko, I.; Ostrikov, K.; Cvelbar, U.; Mozetic, M.; Azarenkov, N. A.

    2008-10-01

    A theoretical model to describe the plasma-assisted growth of carbon nanofibers (CNFs) is proposed. Using the model, the plasma-related effects on the nanofiber growth parameters, such as the growth rate due to surface and bulk diffusion, the effective carbon flux to the catalyst surface, the characteristic residence time and diffusion length of carbon atoms on the catalyst surface, and the surface coverages, have been studied. The dependence of these parameters on the catalyst surface temperature and ion and etching gas fluxes to the catalyst surface is quantified. The optimum conditions under which a low-temperature plasma environment can benefit the CNF growth are formulated. These results are in good agreement with the available experimental data on CNF growth and can be used for optimizing synthesis of related nanoassemblies in low-temperature plasma-assisted nanofabrication.

  11. Electrochemical enzymatic biosensors using carbon nanofiber nanoelectrode arrays

    Science.gov (United States)

    Li, Jun; Li, Yi-fen; Swisher, Luxi Z.; Syed, Lateef U.; Prior, Allan M.; Nguyen, Thu A.; Hua, Duy H.

    2012-10-01

    The reduction of electrode size down to nanometers could dramatically enhance detection sensitivity and temporal resolution. Nanoelectrode arrays (NEAs) are of particular interest for ultrasensitive biosensors. Here we report the study of two types of biosensors for measuring enzyme activities using NEAs fabricated with vertically aligned carbon nanofibers (VACNFs). VACNFs of ~100 nm in average diameter and 3-5 μm in length were grown on conductive substrates as uniform vertical arrays which were then encapsulated in SiO2 matrix leaving only the tips exposed. We demonstrate that such VACNF NEAs can be used in profiling enzyme activities through monitoring the change in electrochemical signals induced by enzymatic reactions to the peptides attached to the VACNF tip. The cleavage of the tetrapeptide with a ferrocene tag by a cancerrelated protease (legumain) was monitored with AC voltammetry. Real-time electrochemical impedance spectroscopy (REIS) was used for fast label-free detection of two reversible processes, i.e. phosphorylation by c-Src tyrosine kinase and dephosphorylation by protein tyrosine phosphatase 1B (PTP1B). The REIS data of phosphorylation were slow and unreliable, but those of dephosphorylation showed large and fast exponential decay due to much higher activity of phosphatase PTP1B. The kinetic data were analyzed with a heterogeneous Michaelis-Menten model to derive the "specificity constant" kcat/Km, which is 8.2x103 M-1s-1 for legumain and (2.1 ± 0.1) x 107 M-1s-1 for phosphatase (PTP1B), well consistent with literature. It is promising to develop VACNF NEA based electrochemical enzymatic biosensors as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring.

  12. Confined self-assembly approach to produce ultrathin carbon nanofibers.

    Science.gov (United States)

    Zhang, Weixia; Cui, Jiecheng; Tao, Cheng-An; Lin, Changxu; Wu, Yiguang; Li, Guangtao

    2009-07-21

    A surfactant containing a terminal carbon source moiety was synthesized and used simultaneously as both template molecule and carbon source. On the basis of this special structure-directing agent, an efficient strategy for producing uniform carbon nanowires with diameter below 1 nm was developed using a confined self-assembly approach. Besides the capability of producing ultralong and thin carbon wires inaccessible by the previously reported approaches, the method described here presents many advantages such as the direct use of residue iron complex as catalyst for carbonization and no requirement of conventional tedious infiltration process of carbon source into small channels. Different methods including SEM, TEM, XRD, Raman spectroscopy, and conductivity measurement were employed to characterize the formed ultrathin carbon nanofibers. Additionally, the described strategy is extendable. By designing an appropriate surfactant, it is also possible for the fabrication of the finely structured carbon network and ultrathin graphitic sheets through the construction of the corresponding cubic and lamellar mesostructured templates.

  13. Carbon nanofibers grown on metallic filters as novel catalytic materials

    OpenAIRE

    Tribolet, Pascal; Kiwi-Minsker, Lioubov

    2005-01-01

    Carbon nanofibers (CNF) were synthesized on sintered metal fibers (SMF) filters of nickel and Ni-containing alloys (Inconel, stainless steel (SS)) by thermal chemical vapor deposition of ethane in the presence of hydrogen at not, vert, similar660 °C. The CNFs were formed directly over the SMF filters without deposition of metal particles. The catalytic active sites leading to the CNF formation were attained by oxidation–reduction of the SMF filter. The CNFs present platelet morphology as dete...

  14. Indirect involvement of armorphous carbon layer on convective heat transfer enhancement using carbon nanofibers

    NARCIS (Netherlands)

    Taha, T.J.; Lefferts, L.; Meer, van der T.H.

    2015-01-01

    In this work, an experimental heat transfer investigation was carried out to investigate the combined influence of both amorphous carbon (a-C) layer thickness and carbon nanofibers (CNFs) on the convective heat transfer behavior. Synthesis of these carbon nanostructures was achieved using catalytic

  15. Nucleation, Growth, and Alignment of Poly(3-hexylthiophene) Nanofibers for High-Performance OFETs.

    Science.gov (United States)

    Persson, Nils E; Chu, Ping-Hsun; McBride, Michael; Grover, Martha; Reichmanis, Elsa

    2017-02-24

    Conjugated semiconducting polymers have been the subject of intense study for over two decades with promising advances toward a printable electronics manufacturing ecosystem. These materials will deliver functional electronic devices that are lightweight, flexible, large-area, and cost-effective, with applications ranging from biomedical sensors to solar cells. Synthesis of novel molecules has led to significant improvements in charge carrier mobility, a defining electrical performance metric for many applications. However, the solution processing and thin film deposition of conjugated polymers must also be properly controlled to obtain reproducible device performance. This has led to an abundance of research on the process-structure-property relationships governing the microstructural evolution of the model semicrystalline poly(3-hexylthiophene) (P3HT) as applied to organic field effect transistor (OFET) fabrication. What followed was the production of an expansive body of work on the crystallization, self-assembly, and charge transport behavior of this semiflexible polymer whose strong π-π stacking interactions allow for highly creative methods of structural control, including the modulation of solvent and solution properties, flow-induced crystallization and alignment techniques, structural templating, and solid-state thermal and mechanical processing. This Account relates recent progress in the microstructural control of P3HT thin films through the nucleation, growth, and alignment of P3HT nanofibers. Solution-based nanofiber formation allows one to develop structural order prior to thin film deposition, mitigating the need for intricate deposition processes and enabling the use of batch and continuous chemical processing steps. Fiber growth is framed as a traditional crystallization problem, with the balance between nucleation and growth rates determining the fiber size and ultimately the distribution of grain boundaries in the solid state. Control of

  16. Preparation of porous carbon nanofibers derived from PBI/PLLA for supercapacitor electrodes

    Science.gov (United States)

    Jung, Kyung-Hye; Ferraris, John P.

    2016-10-01

    Porous carbon nanofibers were prepared by electrospinning blend solutions of polybenzimidazole/poly-L-lactic acid (PBI/PLLA) and carbonization. During thermal treatment, PLLA was decomposed, resulting in the creation of pores in the carbon nanofibers. From SEM images, it is shown that carbon nanofibers had diameters in the range of 100-200 nm. The conversion of PBI to carbon was confirmed by Raman spectroscopy, and the surface area and pore volume of carbon nanofibers were determined using nitrogen adsorption/desorption analyses. To investigate electrochemical performances, coin-type cells were assembled using free-standing carbon nanofiber electrodes and ionic liquid electrolyte. cyclic voltammetry studies show that the PBI/PLLA-derived porous carbon nanofiber electrodes have higher capacitance due to lower electrochemical impedance compared to carbon nanofiber electrode from PBI only. These porous carbon nanofibers were activated using ammonia for further porosity improvement and annealed to remove the surface functional groups to better match the polarity of electrode and electrolyte. Ragone plots, correlating energy density with power density calculated from galvanostatic charge-discharge curves, reveal that activation/annealing further improves energy and power densities.

  17. Novel Continuous Carbon Nanofibers for the Next Generation Lightweight Structural Nanocomposites

    Science.gov (United States)

    2007-05-01

    Presentations Dzenis, Y., "Novel Continuous Carbon Nanofibers and Nanocomposites", 2006 AFOSR Polymer Matrix Composite Review, Long Beach, April 2006...Dzenis, Y., "Novel Continuous Carbon Nanofibers and Nanocomposites", 2005 AFOSR Polymer Matrix Composite Review, San Diego, August 2005 Dzenis, Y., "Next...34Electrospinning of Nanofibers for Composite Laminates", 2004 Polymer Matrix Composite Review, Long Beach, CA, May 2004 (Presented by Dr. X. Wu) Dzenis

  18. Influence of carbon nanofiber properties as electrocatalyst support on the electrochemical performance for PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sebastian, D.; Suelves, I.; Moliner, R.; Lazaro, M.J. [Instituto de Carboquimica (CSIC), Energy and Environment, C/Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Calderon, J.C.; Gonzalez-Exposito, J.A.; Pastor, E. [Universidad de La Laguna, Dpto de Quimica-Fisica, Avda. Astrofisico Francisco Sanchez s/n, 38071 La Laguna, Tenerife (Spain); Martinez-Huerta, M.V. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, 28049 Madrid (Spain)

    2010-09-15

    Novel carbonaceous supports for electrocatalysts are being investigated to improve the performance of polymer electrolyte fuel cells. Within several supports, carbon nanofibers blend two properties that rarely coexist in a material: a high mesoporosity and a high electrical conductivity, due to their particular structure. Carbon nanofibers have been obtained by catalytic decomposition of methane, optimizing growth conditions to obtain carbon supports with different properties. Subsequently, the surface chemistry has been modified by an oxidation treatment, in order to create oxygen surface groups of different nature that have been observed to be necessary to obtain a higher performance of the electrocatalyst. Platinum has then been supported on the as-prepared carbon nanofibers by different deposition methods and the obtained catalysts have been studied by different electrochemical techniques. The influence of carbon nanofibers properties and functionalization on the electrochemical behavior of the electrocatalysts has been studied and discussed, obtaining higher performances than commercial electrocatalysts with the highest electrical conductive carbon nanofibers as support. (author)

  19. Carbon Nanofibers Grown on Large Woven Cloths: Morphology and Properties of Growth

    NARCIS (Netherlands)

    Koissin, Vitaly; Bor, Ton; Kotanjac, Zeljko; Lefferts, Leon; Warnet, Laurent; Akkerman, Remko

    2016-01-01

    The morphology and chemical composition of carbon nanofibers in situ grown on a large carbon-fiber woven fabric are studied using SEM measurements, X-ray Diffraction, X-ray Flourescence, and X-ray Photoelectron Spectroscopy. Results show that nanofibers can have a density and a morphology potentiall

  20. Controlled Deposition and Alignment of Carbon Nanotubes

    Science.gov (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  1. High Performance Flexible Piezoelectric Nanogenerators based on BaTiO3 Nanofibers in Different Alignment Modes.

    Science.gov (United States)

    Yan, Jing; Jeong, Young Gyu

    2016-06-22

    Piezoelectric nanogenerators, harvesting energy from mechanical stimuli in our living environments, hold great promise to power sustainable self-sufficient micro/nanosystems and mobile/portable electronics. BaTiO3 as a lead-free material with high piezoelectric coefficient and dielectric constant has been widely examined to realize nanogenerators, capacitors, sensors, etc. In this study, polydimethylsiloxane (PDMS)-based flexible composites including BaTiO3 nanofibers with different alignment modes were manufactured and their piezoelectric performance was examined. For the study, BaTiO3 nanofibers were prepared by an electrospinning technique utilizing a sol-gel precursor and following calcination process, and they were then aligned vertically or horizontally or randomly in PDMS matrix-based nanogenerators. The morphological structures of BaTiO3 nanofibers and their nanogenerators were analyzed by using SEM images. The crystal structures of the nanogenerators before and after poling were characterized by X-ray diffraction. The dielectric and piezoelectric properties of the nanogenerators were investigated as a function of the nanofiber alignment mode. The nanogenerator with BaTiO3 nanofibers aligned vertically in the PDMS matrix sheet achieved high piezoelectric performance of an output power of 0.1841 μW with maximum voltage of 2.67 V and current of 261.40 nA under a low mechanical stress of 0.002 MPa, in addition to a high dielectric constant of 40.23 at 100 Hz. The harvested energy could thus power a commercial LED directly or be stored into capacitors after rectification.

  2. Occupational nanosafety considerations for carbon nanotubes and carbon nanofibers.

    Science.gov (United States)

    Castranova, Vincent; Schulte, Paul A; Zumwalde, Ralph D

    2013-03-19

    Carbon nanotubes (CNTs) are carbon atoms arranged in a crystalline graphene lattice with a tubular morphology. CNTs exhibit high tensile strength, possess unique electrical properties, are durable, and can be functionalized. These properties allow applications as structural materials, in electronics, as heating elements, in batteries, in the production of stain-resistant fabric, for bone grafting and dental implants, and for targeted drug delivery. Carbon nanofibers (CNFs) are strong, flexible fibers that are currently used to produce composite materials. Agitation can lead to aerosolized CNTs and CNFs, and peak airborne particulate concentrations are associated with workplace activities such as weighing, transferring, mixing, blending, or sonication. Most airborne CNTs or CNFs found in workplaces are loose agglomerates of micrometer diameter. However, due to their low density, they linger in workplace air for a considerable time, and a large fraction of these structures are respirable. In rat and mouse models, pulmonary exposure to single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), or CNFs causes the following pulmonary reactions: acute pulmonary inflammation and injury, rapid and persistent formation of granulomatous lesions at deposition sites of large CNT agglomerates, and rapid and progressive alveolar interstitial fibrosis at deposition sites of more dispersed CNT or CNF structures. Pulmonary exposure to SWCNTs can induce oxidant stress in aortic tissue and increases plaque formation in an atherosclerotic mouse model. Pulmonary exposure to MWCNTs depresses the ability of coronary arterioles to respond to dilators. These cardiovascular effects may result from neurogenic signals from sensory irritant receptors in the lung. Pulmonary exposure to MWCNTs also upregulates mRNA for inflammatory mediators in selected brain regions, and pulmonary exposure to SWCNTs upregulates the baroreceptor reflex. In addition, pulmonary exposure to

  3. Carbon-coated Li3 N nanofibers for advanced hydrogen storage.

    Science.gov (United States)

    Xia, Guanglin; Li, Dan; Chen, Xiaowei; Tan, Yingbin; Tang, Ziwei; Guo, Zaiping; Liu, Huakun; Liu, Zongwen; Yu, Xuebin

    2013-11-20

    3D porous carbon-coated Li3 N nanofibers are successfully fabricated via the electrospinning technique. The as-prepared nanofibers exhibit a highly improved hydrogen-sorption performance in terms of both thermodynamics and kinetics. More interestingly, a stable regeneration can be achieved due to the unique structure of the nanofibers, over 10 cycles of H2 sorption at a temperature as low as 250 °C.

  4. Occupational Exposure to Carbon Nanotubes and Nanofibers

    Science.gov (United States)

    ... and applications. A number of research studies with rodents have shown adverse lung effects at relatively low- ... findings from a new laboratory study in which mice were exposed by inhalation to multi-walled carbon ...

  5. Soft-templated synthesis of mesoporous carbon nanospheres and hollow carbon nanofibers

    Science.gov (United States)

    Cheng, Youliang; Li, Tiehu; Fang, Changqing; Zhang, Maorong; Liu, Xiaolong; Yu, Ruien; Hu, Jingbo

    2013-10-01

    Using coal tar pitch based amphiphilic carbonaceous materials (ACMs) as the precursor and amphiphilic triblock copolymer Plutonic P123 as the only soft template, carbon nanospheres with partially ordered mesopores and hollow carbon nanofibers were synthesized. The concentration of P123, cp, and the mass ratio of P123 to ACM, r, are the key parameters of controlling the shape of the as-prepared products. Mesoporous carbon nanospheres with diameter of 30-150 nm were prepared under the condition of cp = 13.3 g/L and r = 1.2. When cp = 26.7 g/L and r = 2, hollow carbon nanofibers with diameters of 50-200 nm and mesopores/macropores were obtained. Carbon nanospheres and hollow carbon fibers were amorphous materials. The mesoporous carbon nanospheres show good stability in the cyclic voltammograms and their specific capacitance at 10 mV s-1 is 172.1 F/g.

  6. Efficient Roll-on Transfer Technique for Well-Aligned Organic Nanofibers

    DEFF Research Database (Denmark)

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    2011-01-01

    A transfer technique enabling efficient device integration of fragile organic nanostructures is presented. The technique is capable of transferring organic nanofibers to arbitrary substrates, the preservation of nanofiber morphology is demonstrated, and the optical properties are unaffected or ev...

  7. Creation of surface defects on carbon nanofibers by steam treatment

    Institute of Scientific and Technical Information of China (English)

    Zhengfeng; Shao; Min; Pang; Wei; Xia; Martin; Muhler; Changhai; Liang

    2013-01-01

    A direct strategy for the creation of defects on carbon nanofibers (CNFs) has been developed by steam treatment.Nitrogen physisorption,XRD,Raman spectra,SEM and TEM analyses proved the existence of the new defects on CNFs.BET surface area of CNFs after steam treatment was enhanced from 20 to 378 m2/g.Pd catalysts supported on CNFs were also prepared by colloidal deposition method.The different activity of Pd/CNFs catalysts in the partial hydrogenation of phenylacetylene further demonstrated the diverse surfaces of CNFs could be formed by steam treatment.

  8. Pore-Structure-Optimized CNT-Carbon Nanofibers from Starch for Rechargeable Lithium Batteries

    Directory of Open Access Journals (Sweden)

    Yongjin Jeong

    2016-12-01

    Full Text Available Porous carbon materials are used for many electrochemical applications due to their outstanding properties. However, research on controlling the pore structure and analyzing the carbon structures is still necessary to achieve enhanced electrochemical properties. In this study, mesoporous carbon nanotube (CNT-carbon nanofiber electrodes were developed by heat-treatment of electrospun starch with carbon nanotubes, and then applied as a binder-free electrochemical electrode for a lithium-ion battery. Using the unique lamellar structure of starch, mesoporous CNT-carbon nanofibers were prepared and their pore structures were controlled by manipulating the heat-treatment conditions. The activation process greatly increased the volume of micropores and mesopores of carbon nanofibers by etching carbons with CO2 gas, and the Brunauer-Emmett-Teller (BET specific area increased to about 982.4 m2·g−1. The activated CNT-carbon nanofibers exhibited a high specific capacity (743 mAh·g−1 and good cycle performance (510 mAh·g−1 after 30 cycles due to their larger specific surface area. This condition presents many adsorption sites of lithium ions, and higher electrical conductivity, compared with carbon nanofibers without CNT. The research suggests that by controlling the heat-treatment conditions and activation process, the pore structure of the carbon nanofibers made from starch could be tuned to provide the conditions needed for various applications.

  9. Titanium carbide/carbon composite nanofibers prepared by a plasma process

    Energy Technology Data Exchange (ETDEWEB)

    El Mel, A A; Gautron, E; Angleraud, B; Granier, A; Tessier, P Y [Universite de Nantes, CNRS, Institut des Materiaux Jean Rouxel, UMR 6502, 2 rue de la Houssiniere BP 32229-44322 Nantes cedex 3 (France); Choi, C H [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

    2010-10-29

    The incorporation of metal or metal carbide nanoparticles into carbon nanofibers modifies their properties and enlarges their field of application. The purpose of this work is to report a new non-catalytic and easy method to prepare organized metal carbide-carbon composite nanofibers on nanopatterned silicon substrates prepared by laser interference lithography coupled with deep reactive ion etching. Titanium carbide-carbon composite nanofibers were grown on the top of the silicon lines parallel to the substrate by a hybrid plasma process combining physical vapor deposition and plasma enhanced chemical vapor deposition. The prepared nanofibers were analyzed by scanning electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. We demonstrate that the shape, microstructure and the chemical composition of the as-grown nanofibers can be tuned by changing the plasma conditions.

  10. Titanium carbide/carbon composite nanofibers prepared by a plasma process.

    Science.gov (United States)

    El Mel, A A; Gautron, E; Choi, C H; Angleraud, B; Granier, A; Tessier, P Y

    2010-10-29

    The incorporation of metal or metal carbide nanoparticles into carbon nanofibers modifies their properties and enlarges their field of application. The purpose of this work is to report a new non-catalytic and easy method to prepare organized metal carbide-carbon composite nanofibers on nanopatterned silicon substrates prepared by laser interference lithography coupled with deep reactive ion etching. Titanium carbide-carbon composite nanofibers were grown on the top of the silicon lines parallel to the substrate by a hybrid plasma process combining physical vapor deposition and plasma enhanced chemical vapor deposition. The prepared nanofibers were analyzed by scanning electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. We demonstrate that the shape, microstructure and the chemical composition of the as-grown nanofibers can be tuned by changing the plasma conditions.

  11. Method for production of polymer and carbon nanofibers from water-soluble polymers.

    Science.gov (United States)

    Spender, Jonathan; Demers, Alexander L; Xie, Xinfeng; Cline, Amos E; Earle, M Alden; Ellis, Lucas D; Neivandt, David J

    2012-07-11

    Nanometer scale carbon fibers (carbon nanofibers) are of great interest to scientists and engineers in fields such as materials science, composite production, and energy storage due to their unique chemical, physical, and mechanical properties. Precursors currently used for production of carbon nanofibers are primarily from nonrenewable resources. Lignin is a renewable natural polymer existing in all high-level plants that is a byproduct of the papermaking process and a potential feedstock for carbon nanofiber production. The work presented here demonstrates a process involving the rapid freezing of an aqueous lignin solution, followed by sublimation of the resultant ice, to form a uniform network comprised of individual interconnected lignin nanofibers. Carbonization of the lignin nanofibers yields a similarly structured carbon nanofiber network. The methodology is not specific to lignin; nanofibers of other water-soluble polymers have been successfully produced. This nanoscale fibrous morphology has not been observed in traditional cryogel processes, due to the relatively slower freezing rates employed compared to those achieved in this study.

  12. Functionalization of vertically aligned carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Eloise Van Hooijdonk

    2013-02-01

    Full Text Available This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs. The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs.

  13. The influence of specimen thickness and alignment on the material and failure properties of electrospun polycaprolactone nanofiber mats.

    Science.gov (United States)

    Mubyana, Kuwabo; Koppes, Ryan A; Lee, Kristen L; Cooper, James A; Corr, David T

    2016-11-01

    Electrospinning is a versatile fabrication technique that has been recently expanded to create nanofibrous structures that mimic ECM topography. Like many materials, electrospun constructs are typically characterized on a smaller scale, and scaled up for various applications. This established practice is based on the assumption that material properties, such as toughness, failure stress and strain, are intrinsic to the material, and thus will not be influenced by specimen geometry. However, we hypothesized that the material and failure properties of electrospun nanofiber mats vary with specimen thickness. To test this, we mechanically characterized polycaprolactone (PCL) nanofiber mats of three different thicknesses in response to constant rate elongation to failure. To identify if any observed thickness-dependence could be attributed to fiber alignment, such as the effects of fiber reorientation during elongation, these tests were performed in mats with either random or aligned nanofiber orientation. Contrary to our hypothesis, the failure strain was conserved across the different thicknesses, indicating similar maximal elongation for specimens of different thickness. However, in both the aligned and randomly oriented groups, the ultimate tensile stress, short-range modulus, yield modulus, and toughness all decreased with increasing mat thickness, thereby indicating that these are not intrinsic material properties. These findings have important implications in engineered scaffolds for fibrous and soft tissue applications (e.g., tendon, ligament, muscle, and skin), where such oversights could result in unwanted laxity or reduced resistance to failure. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2794-2800, 2016.

  14. A catechol biosensor based on electrospun carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Dawei Li

    2014-03-01

    Full Text Available Carbon nanofibers (CNFs were prepared by combining electrospinning with a high-temperature carbonization technique. And a polyphenol biosensor was fabricated by blending the obtained CNFs with laccase and Nafion. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR and field emission scanning electron microscope (FE-SEM were, respectively, employed to investigate the structures and morphologies of the CNFs and of the mixtures. Cyclic voltammetry and chronoamperometry were employed to study the electrocatalysis of the catechol biosensor. The results indicated that the sensitivity of the biosensor was 41 µA·mM−1, the detection limit was 0.63 µM, the linear range was 1–1310 µM and the response time was within 2 seconds, which excelled most other laccase-based biosensor reported. Furthermore, the biosensor showed good repeatability, reproducibility, stability and tolerance to interferences. This novel biosensor also demonstrated its promising application in detecting catechol in real water samples.

  15. A catechol biosensor based on electrospun carbon nanofibers

    Science.gov (United States)

    Li, Dawei; Pang, Zengyuan; Chen, Xiaodong; Luo, Lei; Cai, Yibing

    2014-01-01

    Summary Carbon nanofibers (CNFs) were prepared by combining electrospinning with a high-temperature carbonization technique. And a polyphenol biosensor was fabricated by blending the obtained CNFs with laccase and Nafion. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FE-SEM) were, respectively, employed to investigate the structures and morphologies of the CNFs and of the mixtures. Cyclic voltammetry and chronoamperometry were employed to study the electrocatalysis of the catechol biosensor. The results indicated that the sensitivity of the biosensor was 41 µA·mM−1, the detection limit was 0.63 µM, the linear range was 1–1310 µM and the response time was within 2 seconds, which excelled most other laccase-based biosensor reported. Furthermore, the biosensor showed good repeatability, reproducibility, stability and tolerance to interferences. This novel biosensor also demonstrated its promising application in detecting catechol in real water samples. PMID:24778958

  16. Carbon nanofibers synthesized by pyrolysis of chloroform and ethanol mixture

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wang-Hua [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Li, Yuan-Yao, E-mail: chmyyl@ccu.edu.tw [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Advanced Institute of Manufacturing with High-Tech Innovations, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China)

    2015-08-01

    Platelet graphite nanofibers (PGNFs) and turbostratic carbon nanofibers (TSCNFs) were synthesized by the pyrolysis of 3 and 10 vol% chloroform in ethanol, respectively, in the presence of Ni catalyst at 700 °C. Auger electron spectrometry analysis reveals that the participation of chloroform in the synthesis led to Ni–Cl bonding on the surface of the catalysts, resulting in a relatively poor crystalline layer and a coarse surface. Furthermore, the Ni–Cl compound affected the melting point and mobility of Ni, changing the morphology and geometrical shape of Ni particles. A low amount of chlorine in the catalyst led to the formation of smaller catalyst particles with a flat surface, resulting in graphene nanosheets stacked perpendicular to the fiber axis, which became PGNFs. In contrast, a high amount of chlorine in the catalyst led to the aggregation of the catalyst and thus the formation of large catalyst particles with a rough surface, resulting in the random stacking of graphene nanosheets, which became TSCNFs. The participation of chlorine was found to be important in the synthesis of the PGNFs and TSCNFs. - Graphical abstract: Display Omitted - Highlights: • The morphology of CNFs changed while different amount of CHCl{sub 3} presented. • The interaction of Ni and Cl changed the geometry and morphology of catalysts. • The structure of CNFs formed attributed to the surface morphology of catalysts. • PGNFs and TSCNFs were perpendicular and random stacking of graphene.

  17. Tunable Graphitic Carbon Nano-Onions Development in Carbon Nanofibers for Multivalent Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Haiqing L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    We developed a novel porous graphitic carbon nanofiber material using a synthesis strategy combining electrospinning and catalytic graphitization. RF hydrogel was used as carbon precursors, transition metal ions were successfully introduced into the carbon matrix by binding to the carboxylate groups of a resorcinol derivative. Transition metal particles were homogeneously distributed throughout the carbon matrix, which are used as in-situ catalysts to produce graphitic fullerene-like nanostructures surrounding the metals. The success design of graphitic carbons with enlarged interlayer spacing will enable the multivalent ion intercalation for the development of multivalent rechargeable batteries.

  18. Production of Carbon Nanofibers Using a CVD Method with Lithium Fluoride as a Supported Cobalt Catalyst

    Directory of Open Access Journals (Sweden)

    S. A. Manafi

    2008-02-01

    Full Text Available Carbon nanofibers (CNFs have been synthesized in high yield (>70% by catalytic chemical vapor deposition (CCVD on Co/LiF catalyst using acetylene as carbon source. A novel catalyst support (LiF is reported for the first time as an alternative for large-scale production of carbon nanofibers while purification process of nanofibers is easier. In our experiment, the sealed furnace was heated at 700∘C for 0.5 hour (the heating rate was 10∘C/min and then cooled to room temperature in the furnace naturally. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs. The obtained sample was sequentially washed with ethanol, dilutes acid, and distilled water to remove residual impurities, amorphous carbon materials, and remaining of catalyst, and then dried at 110∘C for 24 hours. The combined physical characterization through several techniques, such as high-resolution transmission electron microscope (TEM, scanning electron microscope (SEM, thermogarvimetric analysis (TGA, and zeta-sizer and Raman spectroscopy, allows determining the geometric characteristic and the microstructure of individual carbon nanofibers. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs. As a matter of fact, the method of CCVD guarantees the production of CNFs for different applications.

  19. Production of carbon nanofibers in high yields using a sodium chloride support.

    Science.gov (United States)

    Geng, Junfeng; Kinloch, Ian A; Singh, Charanjeet; Golovko, Vladimir B; Johnson, Brian F G; Shaffer, Milo S P; Li, Yali; Windle, Alan H

    2005-09-08

    A new route for the highly convenient scalable production of carbon nanofibers on a sodium chloride support has been developed. Since the support is nontoxic and soluble in water, it can be easily removed without damage to the nanofibers and the environment. Nanofiber yields of up to 6500 wt % relative to the nickel catalyst have been achieved in a growth time of 15 min. Electron microscopy (SEM, TEM) and thermal gravimetric analysis (TGA) indicated that the catalytically grown carbon had relatively little thermal over-growth and possessed either a herringbone or a semi-ordered nanostructure, depending on the growth conditions.

  20. Apparent Power Law Scaling of Variable Range Hopping Conduction in Carbonized Polymer Nanofibers

    Science.gov (United States)

    Kim, Kyung Ho; Lara-Avila, Samuel; Kang, Hojin; He, Hans; Eklӧf, Johnas; Hong, Sung Ju; Park, Min; Moth-Poulsen, Kasper; Matsushita, Satoshi; Akagi, Kazuo; Kubatkin, Sergey; Park, Yung Woo

    2016-11-01

    We induce dramatic changes in the structure of conducting polymer nanofibers by carbonization at 800 °C and compare charge transport properties between carbonized and pristine nanofibers. Despite the profound structural differences, both types of systems display power law dependence of current with voltage and temperature, and all measurements can be scaled into a single universal curve. We analyze our experimental data in the framework of variable range hopping and argue that this mechanism can explain transport properties of pristine polymer nanofibers as well.

  1. Laser Carbonization of PAN-Nanofiber Mats with Enhanced Surface Area and Porosity.

    Science.gov (United States)

    Go, Dennis; Lott, Philipp; Stollenwerk, Jochen; Thomas, Helga; Möller, Martin; Kuehne, Alexander J C

    2016-10-17

    Here we present a novel laser process to generate carbon nanofiber nonwovens from polyacrylonitrile. We produce carbon nanofabrics via electrospinning followed by infrared laser-induced carbonization, facilitating high surface area and well-controlled hierarchical porosity. The process allows precise control of the carbonization conditions and provides high nanoscale porosity. In comparison with classical thermal carbonization, the laser process produces much higher surface areas and smaller pores. Furthermore, we investigate the carbonization performance and the morphology of polyacrylonitrile nanofibers compounded with graphene nanoplatelet fillers.

  2. Bulk scale production of carbon nanofibers in an economical way

    Science.gov (United States)

    Rajarao, Ravindra; Bhat, Badekai Ramachandra

    2012-12-01

    An economical route for the scalable production of carbon nanofibers (CNFs) on a sodium chloride support has been developed. CNFs have been synthesized by chemical vapor deposition (CVD) method by using metal formate as catalyst precursors at 680°C. Products were characterized by SEM, TEM, Raman spectroscopy and XRD method. By thermal analysis, the purity of the as grown products and purified products were determined. This method avoids calcination and reduction process which was employed in commercial catalysts such as metal oxide or nitrate. The problems such as detrimental effect, environmental and even cost have been overcome by using sodium chloride as support. The yield of CNFs up to 7800 wt.% relative to the nickel catalyst has been achieved in the growth time of 15 min. The advantage of this synthesis technique is the simplicity and use of easily available low cost precursors.

  3. Change in carbon nanofiber resistance from ambient to vacuum

    Directory of Open Access Journals (Sweden)

    Shusaku Maeda

    2011-06-01

    Full Text Available The electrical properties of carbon nanofibers (CNFs can be affected by adsorbed gas species. In this study, we compare the resistance values of CNF devices in a horizontal configuration in air and under vacuum. CNFs in air are observed to possess lower current capacities compared to those in vacuum. Further, Joule heating due to current stressing can result in desorption of gas molecules responsible for carrier trapping, leading to lower resistances and higher breakdown currents in vacuum, where most adsorbed gaseous species are evacuated before any significant re-adsorption can occur. A model is proposed to describe these observations, and is used to estimate the number of adsorbed molecules on a CNF device.

  4. Strong magnetic field-assisted growth of carbon nanofibers and its microstructural transformation mechanism

    Science.gov (United States)

    Luo, Chengzhi; Fu, Qiang; Pan, Chunxu

    2015-03-01

    It is well-known that electric and magnetic fields can control the growth direction, morphology and microstructure of one-dimensional carbon nanomaterials (1-DCNMs), which plays a key role for its potential applications in micro-nano-electrics and devices. In this paper, we introduce a novel process for controlling growth of carbon nanofibers (CNFs) with assistance of a strong magnetic field (up to 0.5 T in the center) in a chemical vapor deposition (CVD) system. The results reveal that: 1) The CNFs get bundled when grown in the presence of a strong magnetic field and slightly get aligned parallel to the direction of the magnetic field; 2) The CNFs diameter become narrowed and homogenized with increase of the magnetic field; 3) With the increase of the magnetic field, the microstructure of CNFs is gradually changed, i.e., the strong magnetic field makes the disordered ``solid-cored'' CNFs transform into a kind of bamboo-liked carbon nanotubes; 4) We propose a mechanism that the reason for these variations and transformation is due to diamagnetic property of carbon atoms, so that it has direction selectivity in the precipitation process.

  5. Physicochemical investigations of carbon nanofiber supported Cu/ZrO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Din, Israf Ud, E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my; Shaharun, Maizatul S., E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia); Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS (Malaysia); Naeem, A., E-mail: naeeem64@yahoo.com [National Centre of Excellence in Physical Chemistry, University of Peshawar (Pakistan)

    2014-10-24

    Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO{sub 2}/CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO{sub 3}). The CNF activated with 5% HNO{sub 3} produced higher surface area which is 155 m{sup 2}/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N{sub 2} adsorption-desorption. The results showed that increase of HNO{sub 3} concentration reduced the surface area and porosity of the catalyst.

  6. Method for production of carbon nanofiber mat or carbon paper

    Energy Technology Data Exchange (ETDEWEB)

    Naskar, Amit K.

    2015-08-04

    Method for the preparation of a non-woven mat or paper made of carbon fibers, the method comprising carbonizing a non-woven mat or paper preform (precursor) comprised of a plurality of bonded sulfonated polyolefin fibers to produce said non-woven mat or paper made of carbon fibers. The preforms and resulting non-woven mat or paper made of carbon fiber, as well as articles and devices containing them, and methods for their use, are also described.

  7. Continuous Growth of Vertically Aligned Carbon Nanotubes Forests

    OpenAIRE

    Guzman de Villoria, Roberto; Wardle, Brian L.

    2011-01-01

    Vertically aligned carbon nanotubes are one of the most promising materials due their numerous applications in flexible electronic devices, biosensors and multifunctional aircraft materials, among others. However, the costly production of aligned carbon nanotubes, generally in a batch process, prevents their commercial use. For the first time, a controlled process to grow aligned carbon nanotubes in a continuous manner is presented. Uniform growth is achieved using 2D and 3D substrates. A sig...

  8. Cobalt/copper-decorated carbon nanofibers as novel non-precious electrocatalyst for methanol electrooxidation

    Science.gov (United States)

    Barakat, Nasser A. M.; El-Newehy, Mohamed; Al-Deyab, Salem S.; Kim, Hak Yong

    2014-01-01

    In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm2 was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications.

  9. Highly oriented carbon nanotube papers made of aligned carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ding; Song Pengcheng; Liu Changhong; Wu Wei; Fan Shoushan [Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: chliu@tsinghua.edu.cn

    2008-02-20

    Paper-like carbon nanotube (CNT) materials have many important applications such as in catalysts, in filtration, actuators, capacitor or battery electrodes, and so on. Up to now, the most popular way of preparing buckypapers has involved the procedures of dispersion and filtration of a suspension of CNTs. In this work, we present a simple and effective macroscopic manipulation of aligned CNT arrays called 'domino pushing' in the preparation of the aligned thick buckypapers with large areas. This simple method can efficiently ensure that most of the CNTs are well aligned tightly in the buckypaper. The initial measurements indicate that these buckypapers have better performance on thermal and electrical conductance. These buckypapers with controllable structure also have many potential applications, including supercapacitor electrodes.

  10. Carbon Nanofiber Nanoelectrodes for Neural Stimulation and Chemical Detection: The Era of Smart Deep Brain Stimulation

    Science.gov (United States)

    Koehne, Jessica E.

    2016-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable "smart" therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  11. Carbon Nanofiber Nanoelectrodes for Neural Stimulation and Chemical Detection: The Era of "Smart" Deep Brain Stimulation

    Science.gov (United States)

    Koehne, Jessica E.

    2016-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  12. Hollow Carbon Nanofiber-Encapsulated Sulfur Cathodes for High Specific Capacity Rechargeable Lithium Batteries

    KAUST Repository

    Zheng, Guangyuan

    2011-10-12

    Sulfur has a high specific capacity of 1673 mAh/g as lithium battery cathodes, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a hollow carbon nanofiber-encapsulated sulfur cathode for effective trapping of polysulfides and demonstrate experimentally high specific capacity and excellent electrochemical cycling of the cells. The hollow carbon nanofiber arrays were fabricated using anodic aluminum oxide (AAO) templates, through thermal carbonization of polystyrene. The AAO template also facilitates sulfur infusion into the hollow fibers and prevents sulfur from coating onto the exterior carbon wall. The high aspect ratio of the carbon nanofibers provides an ideal structure for trapping polysulfides, and the thin carbon wall allows rapid transport of lithium ions. The small dimension of these nanofibers provides a large surface area per unit mass for Li2S deposition during cycling and reduces pulverization of electrode materials due to volumetric expansion. A high specific capacity of about 730 mAh/g was observed at C/5 rate after 150 cycles of charge/discharge. The introduction of LiNO3 additive to the electrolyte was shown to improve the Coulombic efficiency to over 99% at C/5. The results show that the hollow carbon nanofiber-encapsulated sulfur structure could be a promising cathode design for rechargeable Li/S batteries with high specific energy. © 2011 American Chemical Society.

  13. Preparation and characterization of carbon nanofiber-polymide composites

    Science.gov (United States)

    Li, Xiaobing

    Carbon nanofibers (CNFs) are potentially excellent reinforcements in polymer-based composites due to very good mechanical properties, thermal and electrical conductivity, and low cost to manufacture. The dispersion of fibers and the interfacial interaction with the polymer matrix need to be improved for CNF composites to achieve this potential. Treatment of the nanofiber surface with groups that are compatible with the polymer is key to addressing these issues. Attached functional groups may enhance the adhesion between reinforcement phase and matrix phase and reduce the slip of polymer chains on the surfaces of fibers. As a result, load can be transferred to fibers efficiently. In this investigation, CNFs were used as reinforcements in a polyimide (PI) matrix to produce a composite. To improve dispersion of fibers as well as interfacial adhesion, oxidized carbon nanofibers (OCNFs) were functionalized by covalently attaching 1,4-phenylenediamine (1,4-PDA) or polyimide oligomer to the surfaces. The functionalization with diamine was carried out either through direct reaction with OCNFs in dimethylacetimide (DMAc) solvent or through a two-step approach in which oxidized fibers were reacted with thionyl chloride (SOCl2) to improve surface reactivity followed by reaction with PDA in DMAc. The PDA was successfully bonded to the surfaces of fibers using both strategies. The further attachment of oligomer proceeded as expected in DMAc. The functionalized CNFs were characterized using Raman spectroscopy, thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to confirm the functionalization reaction. Raman spectra and XPS spectra qualitatively indicated target chemical bonds were formed in each reaction step. Quantifications of TGA and XPS consistently supported that desired chemical moieties were present on the surfaces of fibers. In short, the interfaces of fibers were tailored with groups that would mimic the structure of polyimide and can

  14. A comparative study of the field emission properties of aligned carbon nanostructures films, from carbon nanotubes to diamond

    Science.gov (United States)

    Le Normand, F.; Cojocaru, C. S.; Fleaca, C.; Li, J. Q.; Vincent, P.; Pirio, G.; Gangloff, L.; Nedellec, Y.; Legagneux, P.

    2007-05-01

    The electron field emission properties of different graphitic and diamond-like nanostructures films are compared. They are prepared in the same CVD chamber on SiO{2}/Si(100) and Si(100) flat surfaces, respectively. These nanostructures are thoroughly characterized by scanning electron emission (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Films of dense aligned carbon nanotubes by far display the lowest threshold fields around few V/μ m and the largest emission currents. Carbon nanofibers, with platelet arrangement of the graphitic planes parallel to the substrate, exhibit higher emission thresholds around 10 V/μ m. Diamond nanostructures, either modified through ammonia incorporation within the gas phase or not, exhibit the largest emission threshold around 25 V/μ m. The high enhancement factors, deduced from the Fowler-Nordheim plots, can explain the low emission thresholds whereas limitations to the electron transport ever occur through different processes (i) surface modifications of the surface, as the transformation of the SiO{2} barrier layer into SiN{x} in the presence of ammonia evidenced by XPS; (ii) different orientation of the graphitic basal planes relative to the direction of electron transport (carbon nanofiber) and (iii) presence of a graphitic nest at the interface of the carbon nanostructure and the substrate, observed when catalyst is deposited through mild evaporation.

  15. microRNA regulatory mechanism by which PLLA aligned nanofibers influence PC12 cell differentiation

    Science.gov (United States)

    Yu, Yadong; Lü, Xiaoying; Ding, Fei

    2015-08-01

    Objective. Aligned nanofibers (AFs) are regarded as promising biomaterials in nerve tissue engineering. However, a full understanding of the biocompatibility of AFs at the molecular level is still challenging. Therefore, the present study focused on identifying the microRNA (miRNA)-mediated regulatory mechanism by which poly-L-lactic acid (PLLA) AFs influence PC12 cell differentiation. Approach. Firstly, the effects of PLLA random nanofibers (RFs)/AFs and PLLA films (control) on the biological responses of PC12 cells that are associated with neuronal differentiation were examined. Then, SOLiD sequencing and cDNA microarray were employed to profile the expressions of miRNAs and mRNAs. The target genes of the misregulated miRNAs were predicted and compared with the mRNA profile data. Functions of the matched target genes (the intersection between the predicted target genes and the experimentally-determined, misregulated genes) were analyzed. Main results. The results revealed that neurites spread in various directions in control and RF groups. In the AF group, most neurites extended in parallel with each other. The glucose consumption and lactic acid production in the RF and AF groups were higher than those in the control group. Compared with the control group, 42 and 94 miRNAs were significantly dysregulated in the RF and AF groups, respectively. By comparing the predicted target genes with the mRNA profile data, five and 87 matched target genes were found in the RF and AF groups, respectively. Three of the matched target genes in the AF group were found to be associated with neuronal differentiation, whereas none had this association in the RF group. The PLLA AFs induced the dysregulation of miRNAs that regulate many biological functions, including axonal guidance, lipid metabolism and long-term potentiation. In particular, two miRNA-matched target gene-biological function modules associated with neuronal differentiation were identified as follows: (1) miR-23b, mi

  16. Growth of carbon nanofibers in plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Denysenko, Igor; Ostrikov, Kostya; Tam, Eugene

    2008-10-01

    A theoretical model describing the plasma-assisted growth of carbon nanofibers with metal catalyst particles on top is proposed. Using the model, the plasma-related effects on the nanofiber growth parameters such us the surface diffusion growth rate, the effective carbon flux to the catalyst surface, the characteristic residence time and diffusion length of carbon on the catalyst surface, and the surface coverages, have been studied. It has been found how these parameters depend on the catalyst surface temperature and ion and etching gas fluxes to the catalyst surface. The optimum conditions under which a low-temperature plasma environment can benefit the carbon nanofiber growth are formulated. It has been also found how the plasma environment affects the temperature distribution over the length of the carbon nanofibers. Conditions when the temperature of the catalyst nanoparticles is higher than the temperature of the substrate holder are determined. The results here are in a good agreement with the available experimental data on the carbon nanofiber growth and can be used for optimizing synthesis of nanoassemblies in low-temperature plasma-assisted nanofabrication.

  17. Vertically aligned nanostructure scanning probe microscope tips

    Science.gov (United States)

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  18. Electrospun carbon-tin oxide composite nanofibers for use as lithium ion battery anodes.

    Science.gov (United States)

    Bonino, Christopher A; Ji, Liwen; Lin, Zhan; Toprakci, Ozan; Zhang, Xiangwu; Khan, Saad A

    2011-07-01

    Composite carbon-tin oxide (C-SnO(2)) nanofibers are prepared by two methods and evaluated as anodes in lithium-ion battery half cells. Such an approach complements the long cycle life of carbon with the high lithium storage capacity of tin oxide. In addition, the high surface-to-volume ratio of the nanofibers improves the accessibility for lithium intercalation as compared to graphite-based anodes, while eliminating the need for binders or conductive additives. The composite nanofibrous anodes have first discharge capacities of 788 mAh g(-1) at 50 mA g(-1) current density, which are greater than pure carbon nanofiber anodes, as well as the theoretical capacity of graphite (372 mAh g(-1)), the traditional anode material. In the first protocol to fabricate the C-SnO(2) composites, tin sulfate is directly incorporated within polyacrylonitrile (PAN) nanofibers by electrospinning. During a thermal treatment the tin salt is converted to tin oxide and the polymer is carbonized, yielding carbon-SnO(2) nanofibers. In the second approach, we soak the nanofiber mats in tin sulfate solutions prior to the final thermal treatment, thereby loading the outer surfaces with SnO(2) nanoparticles and raising the tin content from 1.9 to 8.6 wt %. Energy-dispersive spectroscopy and X-ray diffraction analyses confirm the formation of conversion of tin sulfate to tin oxide. Furthermore, analysis with Raman spectroscopy reveals that the additional salt soak treatment from the second fabrication approach increases in the disorder of the carbon structure, as compared to the first approach. We also discuss the performance of our C-SnO(2) compared with its theoretical capacity and other nanofiber electrode composites previously reported in the literature.

  19. Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure property relationships

    Science.gov (United States)

    Naebe, Minoo; Lin, Tong; Staiger, Mark P.; Dai, Liming; Wang, Xungai

    2008-07-01

    Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde.

  20. Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Naebe, Minoo; Lin Tong; Wang Xungai [Centre for Material and Fibre Innovation, Deakin University, Geelong, VIC 3217 (Australia); Staiger, Mark P [Department of Mechanical Engineering, University of Canterbury, Christchurch (New Zealand); Dai Liming [Department of Chemical and Materials Engineering, University of Dayton, Dayton, OH 45469 (United States)], E-mail: tong.lin@deakin.edu.au

    2008-07-30

    Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde.

  1. Convective heat transfer enhancement using Carbon nanofibers (CNFs): influence of amorphous carbon layer on heat transfer performance

    NARCIS (Netherlands)

    Taha, T.J.; Lefferts, L.; Meer, van der T.H.

    2013-01-01

    In this work, an experimental heat transfer investigation was carried out to investigate the combined influence of both amorphous carbon (a-C) layer thickness and carbon nanofibers (CNFs) on the convective heat transfer behavior. Synthesis of these carbon nano structures was achieved using catalytic

  2. Shear Flow Induced Alignment of Carbon Nanotubes in Natural Rubber

    Directory of Open Access Journals (Sweden)

    Yan He

    2015-01-01

    Full Text Available A new procedure for the fabrication of natural rubber composite with aligned carbon nanotubes is provided in this study. The two-step approach is based on (i the preparation of mixture latex of natural rubber, multiwalled carbon nanotubes, and other components and (ii the orientation of carbon nanotubes by a flow field. Rubber composite sheets filled with variable volume fraction of aligned carbon nanotubes were fabricated and then confirmed by transmission electron microscopy and Raman spectroscopy studies. An obvious increase in thermal conductivity has been obtained after the alignment of carbon nanotubes. The dynamic mechanical analysis was carried out in a tear mode for the composite.

  3. Electrophoretic deposition of iron catalyst on C-fiber textiles for the growth of carbon nanofibers.

    Science.gov (United States)

    Lee, Sang-Won; Lee, Chang-Seop

    2014-11-01

    In this study, carbon nanofibers synthesis has been conducted by chemical vapor deposition on C-fiber textiles coated with an iron catalyst via electrophoretic deposition. C-fiber textiles were oxidized with nitric acid before the iron catalyst was plated by electrophoretic deposition. Due to oxidation, the hydroxyl group was created on the C-fiber textiles and was used as an active site for iron catalyst deposition. It was verified that the iron catalyst was deposited on the C-fiber textiles, while current, voltage, and deposition time varied and the concentration of electrolyte was kept constant in electrophoretic deposition. After being deposited, the iron particles were dried in oven for 24 hours and reduced by hydrogen gas in a furnace. Ethylene gas was introduced for the growth of carbon nanofibers and the growth temperature was then varied to find the optimal growth temperature of the carbon nanofibers. Thus, the characteristics of carbon nanofibers were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), N2-sorption (BET), X-Ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). It is verified that the iron particles were most evenly deposited at 0.1 A for 3 minutes. Carbon nanofibers grew to 150-200 nm most evenly at 600 degrees C via temperature variations in CVD.

  4. Electrochemical Protease Biosensor Based on Enhanced AC Voltammetry Using Carbon Nanofiber Nanoelectrode Arrays.

    Science.gov (United States)

    Swisher, Luxi Z; Syed, Lateef U; Prior, Allan M; Madiyar, Foram R; Carlson, Kyle R; Nguyen, Thu A; Hua, Duy H; Li, Jun

    2013-02-28

    We report an electrochemical method for measuring the activity of proteases using nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). The VACNFs of ~150 nm in diameter and 3 to 5 μm in length were grown on conductive substrates and encapsulated in SiO2 matrix. After polishing and plasma etching, controlled VACNF tips are exposed to form an embedded VACNF NEA. Two types of tetrapeptides specific to cancer-mediated proteases legumain and cathepsin B are covalently attached to the exposed VACNF tip, with a ferrocene (Fc) moiety linked at the distal end. The redox signal of Fc can be measured with AC voltammetry (ACV) at ~1 kHz frequency on VACNF NEAs, showing distinct properties from macroscopic glassy carbon electrodes due to VACNF's unique interior structure. The enhanced ACV properties enable the kinetic measurements of proteolytic cleavage of the surface-attached tetrapeptides by proteases, further validated with a fluorescence assay. The data can be analyzed with a heterogeneous Michaelis-Menten model, giving "specificity constant" kcat /Km as (4.3 ± 0.8) × 10(4) M(-1)s(-1) for cathepsin B and (1.13 ± 0.38) × 10(4) M(-1)s(-1) for legumain. This method could be developed as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring.

  5. Electrochemical stability of carbon nanofibers in proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Garbine [Energy Department, CIDETEC-IK4, Po Miramon, 196, 20009 San Sebastian (Spain); Alcaide, Francisco, E-mail: falcaide@cidetec.es [Energy Department, CIDETEC-IK4, Po Miramon, 196, 20009 San Sebastian (Spain); Miguel, Oscar [Energy Department, CIDETEC-IK4, Po Miramon, 196, 20009 San Sebastian (Spain); Cabot, Pere L. [Laboratori d' Electroquimica de Materials i del Medi Ambient, Dept. Quimica Fisica, Universitat de Barcelona, Marti i Franques, 1-11, 08028 Barcelona (Spain); Martinez-Huerta, M.V.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie 2, Cantoblanco, 28049 Madrid (Spain)

    2011-10-30

    This fundamental study deals with the electrochemical stability of several non-conventional carbon based catalyst supports, intended for low temperature proton exchange membrane fuel cell (PEMFC) cathodes. Electrochemical surface oxidation of raw and functionalized carbon nanofibers, and carbon black for comparison, was studied following a potential step treatment at 25.0 deg. C in acid electrolyte, which mimics the operating conditions of low temperature PEMFCs. Surface oxidation was characterized using cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Cyclic voltammograms clearly showed the presence of the hydroquinone/quinone couple. Furthermore, identification of carbonyl, ether, hydroxyl and carboxyl surface functional groups were made by deconvolution of the XPS spectra. The relative increase in surface oxides on carbon nanofibers during the electrochemical oxidation treatment is significantly smaller than that on carbon black. This suggests that carbon nanofibers are more resistant to the electrochemical corrosion than carbon black under the experimental conditions used in this work. This behaviour could be attributed to the differences found in the microstructure of both kinds of carbons. According to these results, carbon nanofibers possess a high potential as catalyst support to increase the durability of catalysts used in low temperature PEMFC applications.

  6. Pt supported on carbon nanofibers as electrocatalyst for low temperature polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alcaide, Francisco; Alvarez, Garbine; Miguel, Oscar [Dpto. de Energia, CIDETEC, Paseo Miramon, 196, 20009 Donostia/San Sebastian (Spain); Lazaro, Maria Jesus; Moliner, Rafael [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Lopez-Cudero, Ana; Solla-Gullon, Jose; Herrero, Enrique; Aldaz, Antonio [Instituto de Electroquimica, Universidad de Alicante, Apdo. 99, E-03080 Alicante (Spain)

    2009-05-15

    Carbon nanofibers synthesized via the thermo catalytic decomposition of methane were investigated for the first time as an electrocatalyst support in PEMFC cathodes. Their textural and physical properties make them a highly efficient catalyst support for cathodic oxygen reduction in low temperature PEMFC. Tests performed in MEAs showed that Pt supported on carbon nanofibers exhibited an enhancement of ca. 94% in power density at 0.600 V, in comparison with a commercial catalyst supported on conventional carbon black, Pt/Vulcan XC-72R. (author)

  7. Radiation Effects on Polypropylene Carbon Nanofibers Composites: Spectroscopic Investigations

    Science.gov (United States)

    Hamilton, John; Mion, Thomas; Cristian Chipara, Alin; Ibrahim, Elamin I.; Lozano, Karen; Tidrow, Steven; Magdalena Chipara, Dorina; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects their physical and chemical properties (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF) composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA), by Air Force Research Laboratory (FA8650-07-2-5061) and by US Army Research Laboratory/Office (W911NF-08-1-0353).

  8. A novel nano-nonwoven fabric with three-dimensionally dispersed nanofibers: entrapment of carbon nanofibers within nonwovens using the wet-lay process

    Science.gov (United States)

    Karwa, Amogh N.; Barron, Troy J.; Davis, Virginia A.; Tatarchuk, Bruce J.

    2012-05-01

    This study demonstrates, for the first time, the manufacturing of novel nano-nonwovens that are comprised of three-dimensionally distributed carbon nanofibers within the matrices of traditional wet-laid nonwovens. The preparation of these nano-nonwovens involves dispersing and flocking carbon nanofibers, and optimizing colloidal chemistry during wet-lay formation. The distribution of nanofibers within the nano-nonwoven was verified using polydispersed aerosol filtration testing, air permeability, low surface tension liquid capillary porometry, SEM and cyclic voltammetry. All these characterization techniques indicated that nanofiber flocks did not behave as large solid clumps, but retained the ‘nanoporous’ structure expected from nanofibers. These nano-nonwovens showed significant enhancements in aerosol filtration performance. The reduction-oxidation reactions of the functional groups on nanofibers and the linear variation of electric double-layer capacitance with nanofiber loading were measured using cyclic voltammetry. More than 65 m2 (700 ft2) of the composite were made during the demonstration of process scalability using a Fourdrinier-type continuous pilot papermaking machine. The scalability of the process with the control over pore size distribution makes these composites very promising for filtration and other nonwoven applications.

  9. Carbon-coated SnSb nanoparticles dispersed in reticular structured nanofibers for lithium-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xiao [College of Textiles and Clothing, Xin Jiang University, Xinjiang, Urumqi 830046 (China); Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education, Shanghai 201620 (China); Zhou, Huimin; Li, Zhiyong; Shan, Xiaohong [College of Textiles and Clothing, Xin Jiang University, Xinjiang, Urumqi 830046 (China); Xia, Xin, E-mail: xjxiaxin@163.com [College of Textiles and Clothing, Xin Jiang University, Xinjiang, Urumqi 830046 (China); Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education, Shanghai 201620 (China)

    2015-01-25

    Highlights: • Sn{sub 0.92}Sb{sub 0.08}O{sub 2.04} nanoparticles as SnSb alloy precursor. • Carbon-coated SnSb nanoparticles were prepared and then embedded in carbon nanofibers. • The synergic effect of carbon coating and special structure improved cycling stability. - Abstract: Carbon coating and carbon nanofiber processes were used to enhance the cycling performance of SnSb alloys. Carbon-coated SnSb alloys were firstly prepared by a simple hydrothermal method to build the first protection, and then carbon-coated SnSb nanoparticles were embedded in carbon nanofibers via single-spinneret electrospinning followed by carbonization. The crystal structure of carbon-coated SnSb/C hybrid nanofibers was characterized by X-ray diffraction (XRD). The morphologies of carbon-coated SnSb alloys and hybrid nanofibers were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The thermal stability of hybrid nanofibers were determined by thermogravimetric analysis (TGA). The electrochemical properties were investigated as a potential high-capacity anode material for lithium-ion batteries. The results showed that the hybrid nanofibers exhibited excellent electrochemical performance due to the special structure. The carbon shell can effectively hinder the agglomeration of SnSb alloys, while maintaining electronic conduction as well as accommodating drastic volume changes during lithium insertion and extraction and carbon nanofibers formed a further protection. The resultant carbon-coated SnSb nanoparticles dispersed in carbon nanofibers deliver a high capacity of 674 mA h g{sup −1} and a good capacity retention of 68.7% after 50 cycles.

  10. Towards scalable binderless electrodes: carbon coated silicon nanofiber paper via Mg reduction of electrospun SiO2 nanofibers.

    Science.gov (United States)

    Favors, Zachary; Bay, Hamed Hosseini; Mutlu, Zafer; Ahmed, Kazi; Ionescu, Robert; Ye, Rachel; Ozkan, Mihrimah; Ozkan, Cengiz S

    2015-02-06

    The need for more energy dense and scalable Li-ion battery electrodes has become increasingly pressing with the ushering in of more powerful portable electronics and electric vehicles (EVs) requiring substantially longer range capabilities. Herein, we report on the first synthesis of nano-silicon paper electrodes synthesized via magnesiothermic reduction of electrospun SiO2 nanofiber paper produced by an in situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS) in-flight. Free-standing carbon-coated Si nanofiber binderless electrodes produce a capacity of 802 mAh g(-1) after 659 cycles with a Coulombic efficiency of 99.9%, which outperforms conventionally used slurry-prepared graphite anodes by over two times on an active material basis. Silicon nanofiber paper anodes offer a completely binder-free and Cu current collector-free approach to electrode fabrication with a silicon weight percent in excess of 80%. The absence of conductive powder additives, metallic current collectors, and polymer binders in addition to the high weight percent silicon all contribute to significantly increasing capacity at the cell level.

  11. The production of a homogeneous and well-attached layer of carbon nanofibers on metal foils

    NARCIS (Netherlands)

    Pacheco Benito, S.; Lefferts, L.

    2010-01-01

    Carbon nanofibers (CNFs) were deposited on metal foils including nickel (Ni), iron (Fe), cobalt (Co), stainless steel (Fe:Ni; 70:11 wt.%) and mumetal (Ni:Fe; 77:14 wt.%) by the decomposition of C2H4 at 600 °C. The effect of pretreatment and the addition of H2 on the rate of carbon formation, as well

  12. Carbon nanofiber mesoporous films: efficient platforms for bio-hydrogen oxidation in biofuel cells.

    Science.gov (United States)

    de Poulpiquet, Anne; Marques-Knopf, Helena; Wernert, Véronique; Giudici-Orticoni, Marie Thérèse; Gadiou, Roger; Lojou, Elisabeth

    2014-01-28

    The discovery of oxygen and carbon monoxide tolerant [NiFe] hydrogenases was the first necessary step toward the definition of a novel generation of hydrogen fed biofuel cells. The next important milestone is now to identify and overcome bottlenecks limiting the current densities, hence the power densities. In the present work we report for the first time a comprehensive study of herringbone carbon nanofiber mesoporous films as platforms for enhanced biooxidation of hydrogen. The 3D network allows mediatorless hydrogen oxidation by the membrane-bound hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus. We investigate the key physico-chemical parameters that enhance the catalytic efficiency, including surface chemistry and hierarchical porosity of the biohybrid film. We also emphasize that the catalytic current is limited by mass transport inside the mesoporous carbon nanofiber film. Provided hydrogen is supplied inside the carbon film, the combination of the hierarchical porosity of the carbon nanofiber film with the hydrophobicity of the treated carbon material results in very high efficiency of the bioelectrode. By optimization of the whole procedure, current densities as high as 4.5 mA cm(-2) are reached with a turnover frequency of 48 s(-1). This current density is almost 100 times higher than when hydrogenase is simply adsorbed at a bare graphite electrode, and more than 5 times higher than the average of the previous reported current densities at carbon nanotube modified electrodes, suggesting that carbon nanofibers can be efficiently used in future sustainable H2/O2 biofuel cells.

  13. Oxidative steam reforming of ethanol over carbon nanofiber supported Co catalysts

    NARCIS (Netherlands)

    da Silva, A.L.M.; Mattos, L.V.; den Breejen, J.P.; Bitter, J.H.; de Jong, K.P.; Noronha, F.B.

    2011-01-01

    The effect of the cobalt particle size in the ethanol oxidative steam reforming reaction for hydrogen production was investigated using cobalt on carbon nanofiber catalysts. The smallest (4 nm) were quite stable during OSR reaction but significant carbon formation was detected.

  14. Preparation of electrospun Ag/g-C3N4 loaded composite carbon nanofibers for catalytic applications

    Science.gov (United States)

    Yu, Bo; Liu, Yongkun; Jiang, Guohua; Liu, Depeng; Yu, Weijiang; Chen, Hua; Li, Lei; Huang, Qin

    2017-01-01

    In this paper, the electrospun Ag nanoparticles and g-C3N4 (Ag/g-C3N4) loaded composite carbon nanofibers were successfully prepared combing the electrospinning technology and carbonization treatment. The composition and microstructure of the resultant composite nanofibers were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM) and x-ray photoelectron spectrometry (XPS). Due to the synergistic effect between catalytic activity of Ag nanoparticles (NPs) and g-C3N4 and excellent adsorption capacity of carbon nanofibers, the resultant electrospun Ag/g-C3N4 loaded composite carbon nanofibers exhibited excellent conversion of 4-nitrophenol to 4-aminophenol and benzylamine to N-benzylbenzaldimine. The resultant hybrid carbon composite nanofibers offer the significant advantages, such as low dosage, high catalytic activity, easy recycling and excellent stability.

  15. Carbon nanofiber-based luminol-biotin probe for sensitive chemiluminescence detection of protein.

    Science.gov (United States)

    Baj, Stefan; Krawczyk, Tomasz; Pradel, Natalia; Azam, Md Golam; Shibata, Takayuki; Dragusha, Shpend; Skutil, Krzysztof; Pawlyta, Miroslawa; Kai, Masaaki

    2014-01-01

    A carbon nanofiber-based luminol-biotin probe was synthesized for the sensitive chemiluminescence (CL) detection of a target protein by grafting luminol and biotin onto an oxidized carbon nanofiber. This carbon nanofiber was prepared by chemical vapor-deposition with methane in the presence of the Ni-Cu-MgO catalyst, which was followed by oxidization with HNO3-H2SO4 to produce a carboxyl group on the surface of the nanofiber. The material was grafted with luminol and biotin by means of a standard carbodiimide activation of COOH groups to produce corresponding amides. The substance was water-soluble and thus could be utilized as a sensitive CL probe for a protein assay. The probe showed highly specific affinity towards the biotin-labeled antibody via a streptavidin-biotin interaction. The detection limit for this model assay was approximately 0.2 pmol of the biotinized IgG spotted on a polyvinylidene fluoride (PVDF) membrane. Nonspecific binding to other proteins was not observed. Therefore, the synthesized carbon nanofiber-based CL probe may be useful for a sensitive and specific analysis of the target protein.

  16. High-performance supercapacitor electrode from cellulose-derived, inter-bonded carbon nanofibers

    Science.gov (United States)

    Cai, Jie; Niu, Haitao; Wang, Hongxia; Shao, Hao; Fang, Jian; He, Jingren; Xiong, Hanguo; Ma, Chengjie; Lin, Tong

    2016-08-01

    Carbon nanofibers with inter-bonded fibrous structure show high supercapacitor performance when being used as electrode materials. Their preparation is highly desirable from cellulose through a pyrolysis technique, because cellulose is an abundant, low cost natural material and its carbonization does not emit toxic substance. However, interconnected carbon nanofibers prepared from electrospun cellulose nanofibers and their capacitive behaviors have not been reported in the research literature. Here we report a facile one-step strategy to prepare inter-bonded carbon nanofibers from partially hydrolyzed cellulose acetate nanofibers, for making high-performance supercapacitors as electrode materials. The inter-fiber connection shows considerable improvement in electrode electrochemical performances. The supercapacitor electrode has a specific capacitance of ∼241.4 F g-1 at 1 A g-1 current density. It maintains high cycling stability (negligible 0.1% capacitance reduction after 10,000 cycles) with a maximum power density of ∼84.1 kW kg-1. They may find applications in the development of efficient supercapacitor electrodes for energy storage applications.

  17. Facile synthesis of carbon nanofibers-bridged porous carbon nanosheets for high-performance supercapacitors

    Science.gov (United States)

    Jiang, Yuting; Yan, Jun; Wu, Xiaoliang; Shan, Dandan; Zhou, Qihang; Jiang, Lili; Yang, Deren; Fan, Zhuangjun

    2016-03-01

    A facile and one-step method is demonstrated to prepare carbon nanofibers (CNFs)-bridged porous carbon nanosheets (PCNs) through carbonization of the mixture of bacterial cellulose and potassium citrate. The CNFs bridge PCNs to form integrated porous carbon architecture with high specific surface area of 1037 m2 g-1, much higher than those of pure PCNs (381 m2 g-1) and CNFs (510 m2 g-1). As a consequence, the PCN/CNF composite displays high specific capacitance of 261 F g-1, excellent rate capability and outstanding cycling stability (97.6% of capacitance retention after 10000 cycles). Moreover, the assembled symmetric supercapacitor with PCN/CNF electrodes delivers an ultrahigh energy density of 20.4 Wh kg-1 and outstanding cycling life (94.8% capacitance retention after 10000 cycles) in an aqueous electrolyte.

  18. Neurogenic differentiation of human umbilical cord mesenchymal stem cells on aligned electrospun polypyrrole/polylactide composite nanofibers with electrical stimulation

    Science.gov (United States)

    Zhou, Junfeng; Cheng, Liang; Sun, Xiaodan; Wang, Xiumei; Jin, Shouhong; Li, Junxiang; Wu, Qiong

    2016-09-01

    Adult central nervous system (CNS) tissue has a limited capacity to recover after trauma or disease. Recent medical cell therapy using polymeric biomaterialloaded stem cells with the capability of differentiation to specific neural population has directed focuses toward the recovery of CNS. Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal cells. Here we report on the fabrication of an electrospun polypyrrole/polylactide composite nanofiber film that direct or determine the fate of mesenchymal stem cells (MSCs), via combination of aligned surface topography, and electrical stimulation (ES). The surface morphology, mechanical properties and electric properties of the film were characterized. Comparing with that on random surface film, expression of neurofilament-lowest and nestin of human umbilical cord mesenchymal stemcells (huMSCs) cultured on film with aligned surface topography and ES were obviously enhanced. These results suggest that aligned topography combining with ES facilitates the neurogenic differentiation of huMSCs and the aligned conductive film can act as a potential nerve scaffold.

  19. Effect of Filler Orientation on Thermal Conductivity of Polypropylene Matrix Carbon Nanofiber Composites

    Science.gov (United States)

    Enomoto, Kazuki; Fujiwara, Shu; Yasuhara, Toshiyuki; Murakami, Hiroya; Teraki, Junichi; Ohtake, Naoto

    2005-06-01

    Polypropylene matrix carbon nanofiber composites were obtained by injection molding after kneading with a batch-type twin-screw kneader. The thermal conductivity of the composites in the thickness direction was evaluated, with particular focus on the effects of carbon nanofiber (CNF) content and filler orientation. The thermal conductivity of the composites increased with increasing CNF content, and was obtained as 3.46 W/(m\\cdotK) when the CNF content was 50% in weight fraction and the CNFs were highly oriented along the measuring direction of thermal conductivity. This value is approximately seventeenfold higher than that of neat polypropylene.

  20. Mesoporous Carbon Nanofibers Embedded with MoS2 Nanocrystals for Extraordinary Li-Ion Storage.

    Science.gov (United States)

    Hu, Shan; Chen, Wen; Uchaker, Evan; Zhou, Jing; Cao, Guozhong

    2015-12-01

    MoS2 nanocrystals embedded in mesoporous carbon nanofibers are synthesized through an electrospinning process followed by calcination. The resultant nanofibers are 100-150 nm in diameter and constructed from MoS2 nanocrystals with a lateral diameter of around 7 nm with specific surface areas of 135.9 m(2)  g(-1) . The MoS2 @C nanofibers are treated at 450 °C in H2 and comparison samples annealed at 800 °C in N2 . The heat treatments are designed to achieve good crystallinity and desired mesoporous microstructure, resulting in enhanced electrochemical performance. The small amount of oxygen in the nanofibers annealed in H2 contributes to obtaining a lower internal resistance, and thus, improving the conductivity. The results show that the nanofibers obtained at 450 °C in H2 deliver an extraordinary capacity of 1022 mA h g(-1) and improved cyclic stability, with only 2.3 % capacity loss after 165 cycles at a current density of 100 mA g(-1) , as well as an outstanding rate capability. The greatly improved kinetics and cycling stability of the mesoporous MoS2 @C nanofibers can be attributed to the crosslinked conductive carbon nanofibers, the large specific surface area, the good crystallinity of MoS2 , and the robust mesoporous microstructure. The resulting nanofiber electrodes, with short mass- and charge-transport pathways, improved electrical conductivity, and large contact area exposed to electrolyte, permitting fast diffusional flux of Li ions, explains the improved kinetics of the interfacial charge-transfer reaction and the diffusivity of the MoS2 @C mesoporous nanofibers. It is believed that the integration of MoS2 nanocrystals and mesoporous carbon nanofibers may have a synergistic effect, giving a promising anode, and widening the applicability range into high performance and mass production in the Li-ion battery market.

  1. Porous Carbon Nanofibers from Electrospun Biomass Tar/Polyacrylonitrile/Silver Hybrids as Antimicrobial Materials.

    Science.gov (United States)

    Song, Kunlin; Wu, Qinglin; Zhang, Zhen; Ren, Suxia; Lei, Tingzhou; Negulescu, Ioan I; Zhang, Quanguo

    2015-07-15

    A novel route to fabricate low-cost porous carbon nanofibers (CNFs) using biomass tar, polyacrylonitrile (PAN), and silver nanoparticles has been demonstrated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers had average diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the resultant CNFs showed more uniformly sized and reduced average diameters (226-507 nm) compared to as-spun nanofibers. The CNFs exhibited high specific surface area (>400 m(2)/g) and microporosity, attributed to the combined effects of phase separations of the tar and PAN and thermal decompositions of tar components. These pore characteristics increased the exposures and contacts of silver nanoparticles to the bacteria including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, leading to excellent antimicrobial performances of as-spun nanofibers and CNFs. A new strategy is thus provided for utilizing biomass tar as a low-cost precursor to prepare functional CNFs and reduce environmental pollutions associated with direct disposal of tar as an industrial waste.

  2. Strong Metal-Support Interaction: Growth of Individual Carbon Nanofibers from Amorphous Carbon Interacting with an Electron Beam

    DEFF Research Database (Denmark)

    Zhang, Wei; Kuhn, Luise Theil

    2013-01-01

    The article discusses the growth behavior of carbon nanofibers (CNFs). It mentions that CNFs can be synthesized using methods such as arc-discharge, laser ablation and chemical vapor deposition. It further states that CNFs can be grown from a physical mixing of amorphous carbon and CGO...

  3. Effects of carbon nanofiber on physiology of Drosophila

    Directory of Open Access Journals (Sweden)

    Lee SH

    2015-05-01

    Full Text Available Shin-Hae Lee,1,* Hye-Yeon Lee,1,* Eun-Ji Lee,1,* Dongwoo Khang,2 Kyung-Jin Min11Department of Biological Sciences, Inha University, Incheon, Republic of Korea; 2Department of Molecular Medicine, Graduate School of Medicine, Gachon University, Incheon, Republic of Korea*These authors contributed equally to this workAbstract: As nanomaterials are now widely utilized in a wide range of fields for both medical and industrial applications, concerns over their potential toxicity to human health and the environment have increased. To evaluate the toxicity of long-term exposure to carbon nanofibers (CNFs in an in vivo system, we selected Drosophila melanogaster as a model organism. Oral administration of CNFs at a concentration of 1,000 µg/mL had adverse effects on fly physiology. Long-term administration of a high dose of CNFs (1,000 µg/mL reduced larval viability based on the pupa:egg ratio, adult fly lifespan, reproductive activity, climbing activity, and survival rate in response to starvation stress. However, CNFs at a low concentration (100 µg/mL did not show any significant deleterious effect on developmental rate or fecundity. Furthermore, long-term administration of a low dose of CNFs (100 µg/mL increased lifespan and climbing ability, coincident with mild reactive oxygen species generation and stimulation of the antioxidant system. Taken together, our data suggest that a high dose of CNFs has obvious physiological toxicity, whereas low-dose chronic exposure to CNFs can actually have beneficial effects via stimulation of the antioxidant defense system.Keywords: toxicity, Drosophila melanogaster, lifespan, reactive oxygen species

  4. Label-free electrochemical impedance detection of kinase and phosphatase activities using carbon nanofiber nanoelectrode arrays

    Science.gov (United States)

    Li, Yifen; Syed, Lateef; Liu, Jianwei; Hua, Duy H.; Li, Jun

    2012-01-01

    We demonstrate the feasibility of a label-free electrochemical method to detect the kinetics of phosphorylation and dephosphorylation of surface-attached peptides catalyzed by kinase and phosphatase, respectively. The peptides with a sequence specific to c-Src tyrosine kinase and protein tyrosine phosphatase 1B (PTP1B) were first validated with ELISA-based protein tyrosine kinase assay and then functionalized on vertically aligned carbon nanofiber (VACNF) nanoelectrode arrays (NEAs). Real-time electrochemical impedance spectroscopy (REIS) measurements showed reversible impedance changes upon the addition of c-Src kinase and PTP1B phosphatase. Only a small and unreliable impedance variation was observed during the peptide phosphorylation, but a large and fast impedance decrease was observed during the peptide dephosphorylation at different PTP1B concentrations. The REIS data of dephosphorylation displayed a well-defined exponential decay following the Michaelis-Menten heterogeneous enzymatic model with a specific constant, kcat/Km, of (2.1 ± 0.1) × 107 M−1 s−1. Consistent values of the specific constant was measured at PTP1B concentration varying from 1.2 to 2.4 nM with the corresponding electrochemical signal decay constant varying from 38.5 to 19.1 s. This electrochemical method can be potentially used as a label-free method for profiling enzyme activities in fast reactions. PMID:22935373

  5. The fabrication and electrochemical properties of electrospun nanofibers of a multiwalled carbon nanotube grafted by chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Feng Wei; Wu Zigang; Li Yu; Feng Yiyu; Yuan Xiaoyan [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: weifeng@tju.edu.cn

    2008-03-12

    Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution. Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath-core structure; the outer and inner diameters of these sheath-core nanofibers were about 200 nm and 100 nm, respectively. These nanofibers' electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers' web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

  6. The fabrication and electrochemical properties of electrospun nanofibers of a multiwalled carbon nanotube grafted by chitosan

    Science.gov (United States)

    Feng, Wei; Wu, Zigang; Li, Yu; Feng, Yiyu; Yuan, Xiaoyan

    2008-03-01

    Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution. Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath-core structure; the outer and inner diameters of these sheath-core nanofibers were about 200 nm and 100 nm, respectively. These nanofibers' electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers' web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

  7. Fischer-Tropsch synthesis on hierarchically structured cobalt nanoparticle/carbon nanofiber/carbon felt composites.

    Science.gov (United States)

    Zarubova, Sarka; Rane, Shreyas; Yang, Jia; Yu, Yingda; Zhu, Ye; Chen, De; Holmen, Anders

    2011-07-18

    The hierarchically structured carbon nanofibers (CNFs)/carbon felt composites, in which CNFs were directly grown on the surface of microfibers in carbon felt, forming a CNF layer on a micrometer range that completely covers the microfiber surfaces, were tested as a novel support material for cobalt nanoparticles in the highly exothermic Fischer-Tropsch (F-T) synthesis. A compact, fixed-bed reactor, made of disks of such composite materials, offered the advantages of improved heat and mass transfer, relatively low pressure drop, and safe handling of immobilized CNFs. An efficient 3-D thermal conductive network in the composite provided a relatively uniform temperature profile, whereas the open structure of the CNF layer afforded an almost 100 % effectiveness of Co nanoparticles in the F-T synthesis in the fixed bed. The greatly improved mass and heat transport makes the compact reactor attractive for applications in the conversion of biomass, coal, and natural gas to liquids.

  8. Scaling up the Fabrication of Mechanically-Robust Carbon Nanofiber Foams

    Directory of Open Access Journals (Sweden)

    William Curtin

    2016-02-01

    Full Text Available This work aimed to identify and address the main challenges associated with fabricating large samples of carbon foams composed of interwoven networks of carbon nanofibers. Solutions to two difficulties related with the process of fabricating carbon foams, maximum foam size and catalyst cost, were developed. First, a simple physical method was invented to scale-up the constrained formation of fibrous nanostructures process (CoFFiN to fabricate relatively large foams. Specifically, a gas deflector system capable of maintaining conditions supportive of carbon nanofiber foam growth throughout a relatively large mold was developed. ANSYS CFX models were used to simulate the gas flow paths with and without deflectors; the data generated proved to be a very useful tool for the deflector design. Second, a simple method for selectively leaching the Pd catalyst material trapped in the foam during growth was successfully tested. Multiple techniques, including scanning electron microscopy, surface area measurements, and mechanical testing, were employed to characterize the foams generated in this study. All results confirmed that the larger foam samples preserve the basic characteristics: their interwoven nanofiber microstructure forms a low-density tridimensional solid with viscoelastic behavior. Fiber growth mechanisms are also discussed. Larger samples of mechanically-robust carbon nanofiber foams will enable the use of these materials as strain sensors, shock absorbers, selective absorbents for environmental remediation and electrodes for energy storage devices, among other applications.

  9. Electrospun carbon nanofibers for improved electrical conductivity of fiber reinforced composites

    Science.gov (United States)

    Alarifi, Ibrahim M.; Alharbi, Abdulaziz; Khan, Waseem S.; Asmatulu, Ramazan

    2015-04-01

    Polyacrylonitrile (PAN) was dissolved in dimethylformamide (DMF), and then electrospun to generate nanofibers using various electrospinning conditions, such as pump speeds, DC voltages and tip-to-collector distances. The produced nanofibers were oxidized at 270 °C for 1 hr, and then carbonized at 850 °C in an argon gas for additional 1 hr. The resultant carbonized PAN nanofibers were placed on top of the pre-preg carbon fiber composites as top layers prior to the vacuum oven curing following the pre-preg composite curing procedures. The major purpose of this study is to determine if the carbonized nanofibers on the fiber reinforced composites can detect the structural defects on the composite, which may be useful for the structural health monitoring (SHM) of the composites. Scanning electron microscopy images showed that the electrospun PAN fibers were well integrated on the pre-preg composites. Electrical conductivity studies under various tensile loads revealed that nanoscale carbon fibers on the fiber reinforced composites detected small changes of loads by changing the resistance values. Electrically conductive composite manufacturing can have huge benefits over the conventional composites primarily used for the military and civilian aircraft and wind turbine blades.

  10. Flame Synthesis Of Single-Walled Carbon Nanotubes And Nanofibers

    Science.gov (United States)

    Wal, Randy L. Vander; Berger, Gordon M.; Ticich, Thomas M.

    2003-01-01

    Carbon nanotubes are widely sought for a variety of applications including gas storage, intercalation media, catalyst support and composite reinforcing material [1]. Each of these applications will require large scale quantities of CNTs. A second consideration is that some of these applications may require redispersal of the collected CNTs and attachment to a support structure. If the CNTs could be synthesized directly upon the support to be used in the end application, a tremendous savings in post-synthesis processing could be realized. Therein we have pursued both aerosol and supported catalyst synthesis of CNTs. Given space limitations, only the aerosol portion of the work is outlined here though results from both thrusts will be presented during the talk. Aerosol methods of SWNT, MWNT or nanofiber synthesis hold promise of large-scale production to supply the tonnage quantities these applications will require. Aerosol methods may potentially permit control of the catalyst particle size, offer continuous processing, provide highest product purity and most importantly, are scaleable. Only via economy of scale will the cost of CNTs be sufficient to realize the large-scale structural and power applications on both earth and in space. Present aerosol methods for SWNT synthesis include laser ablation of composite metalgraphite targets or thermal decomposition/pyrolysis of a sublimed or vaporized organometallic [2]. Both approaches, conducted within a high temperature furnace, have produced single-walled nanotubes (SWNTs). The former method requires sophisticated hardware and is inherently limited by the energy deposition that can be realized using pulsed laser light. The latter method, using expensive organometallics is difficult to control for SWNT synthesis given a range of gasparticle mixing conditions along variable temperature gradients; multi-walled nanotubes (MWNTs) are a far more likely end products. Both approaches require large energy expenditures and

  11. Remarkable improvement in microwave absorption by cloaking a micro-scaled tetrapod hollow with helical carbon nanofibers.

    Science.gov (United States)

    Jian, Xian; Chen, Xiangnan; Zhou, Zuowan; Li, Gang; Jiang, Man; Xu, Xiaoling; Lu, Jun; Li, Qiming; Wang, Yong; Gou, Jihua; Hui, David

    2015-02-01

    Helical nanofibers are prepared through in situ growth on the surface of a tetrapod-shaped ZnO whisker (T-ZnO), by employing a precursor decomposition method then adding substrate. After heat treatment at 900 °C under argon, this new composite material, named helical nanofiber-T-ZnO, undergoes a significant change in morphology and structure. The T-ZnO transforms from a solid tetrapod ZnO to a micro-scaled tetrapod hollow carbon film by reduction of the organic fiber at 900 °C. Besides, helical carbon nanofibers, generated from the carbonization of helical nanofibers, maintain the helical morphology. Interestingly, HCNFs with the T-hollow exhibit remarkable improvement in electromagnetic wave loss compared with the pure helical nanofibers. The enhanced loss ability may arise from the efficient dielectric friction, interface effect in the complex nanostructures and the micro-scaled tetrapod-hollow structure.

  12. Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

    Science.gov (United States)

    Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

    2016-06-01

    Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for

  13. Carbon Nanofiber Supported Transition-Metal Carbide Catalysts for the Hydrodeoxygenation of Guaiacol

    NARCIS (Netherlands)

    Jongerius, A.; Gosselink, R.W.; Dijkstra, J.; Bitter, J.H.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

    2013-01-01

    Hydrodeoxygenation (HDO) studies over carbon nanofiber-supported (CNF) W2C and Mo2C catalysts were performed on guaiacol, a prototypical substrate to evaluate the potential of a catalyst for valorization of depolymerized lignin streams. Typical reactions were executed at 55 bar hydrogen pressure ove

  14. A self-template strategy for the synthesis of mesoporous carbon nanofibers as advanced supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei; Zhang, Fan; Dou, Yuqian; Wu, Zhangxiong; Liu, Haijing; Qian, Xufang; Gu, Dong; Xia, Yongyao; Tu, Bo; Zhao, Dongyuan [Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and Laboratory of Advanced Materials, Fudan University, Shanghai 200433 (China)

    2011-05-15

    Self-construction: A facile self-templating strategy is presented for the synthesis of mesoporous carbon nanofibers by using zinc glycolate fibers as the built-in template. The spectacular architectures show excellent performances as recommended electrode material for electrochemical capacitors. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Influence of thin film nickel pretreatment on catalytic thermal chemical vapor deposition of carbon nanofibers

    NARCIS (Netherlands)

    Tiggelaar, R.M.; Thakur, D.B.; Nair, H.; Lefferts, L.; Seshan, K.; Gardeniers, J.G.E.

    2013-01-01

    Nickel and other metal nanoparticles are known to be active as catalysts in the synthesis of carbon nanofibers. In this paper we investigate how dewetting and break-up of nickel thin films depends on film thickness, film–substrate interaction and pretreatment conditions. This is evaluated for films

  16. Nanomagnetic domains of chromium deposited on vertically-aligned carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Andrew C., E-mail: a.wright@glyndwr.ac.uk [Advanced Materials Research Laboratory, Materials Science Research Center, Glyndwr University, Wrexham LL11 2AW (United Kingdom); Faulkner, Michael K., E-mail: m.faulkner@manchester.ac.uk [Manchester Materials Science Centre, University of Manchester, Grosvenor Street, Manchester M13 9PL (United Kingdom); Harris, Robert C.; Goddard, Alex; Abbott, Andrew P., E-mail: apa1@le.ac.uk [Department of Chemistry, University of Leicester, Leicester LE1 7RH (United Kingdom)

    2012-12-15

    The drive to create ever smaller magnetic memory devices has led to the development of new nanomagnetic domains on surfaces. This paper reports the development of nano-chromium magnetic domains obtained using electrodeposition on vertically aligned carbon nanofibers arrays. Attempts to achieve this using conventional aqueous solutions were unsuccessful even after thin nickel underlayers were applied. The use of a novel electrolyte, a deep eutectic solvent, made from choline chloride: chromium (III) chloride enabled highly conformal overcoatings of chromium on individual bare carbon nanotubes to be obtained. Very high aspect ratio metal microstructures could be obtained by this novel technology. Magnetic imaging of the coated nanoarrays showed there to be clear magnetic character to the coating when the thin coatings were applied but this disappeared when the deposits were thicker and more contiguous. - Highlights: Black-Right-Pointing-Pointer Nanoscale chromium deposited from non-aqueous electrolyte shows magnetic behavior. Black-Right-Pointing-Pointer Vertically aligned carbon nanotubes conformally coated with chromium metal. Black-Right-Pointing-Pointer Ionic liquid electrolyte superior to chromic acid for plating high aspect ratio structures.

  17. Electrochemical behaviorof carbon paste electrode modified with Carbon Nanofibers: Application to detection of Bisphenol A

    Directory of Open Access Journals (Sweden)

    N.Achargui

    2016-12-01

    Full Text Available The electrochemical behavior of carbon paste electrode modified with carbon nanofibers has been studied using cyclic voltammetry (CV, electrochemical impedance spectroscopy (EIS and scaning electron microscopy. The response of modified electrodein ferroferricyanidesolutionshows reversible behavior and significant increment in current value compared to the bare CPE indicating that CNFs act as efficient electron mediator to catalyze reactions at the surface. The modified electrode has been used to study the electrochemical response of bisphenol Ausing different electrochemical techniques such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and square wave voltammetry. The oxidation peak of BPA was observed at about 0.53 V in phosphate buffer solution at pH 6.7. The oxidation peak current of BPA varied linearly with concentration over a wide range of 5µmol L-1 to 400 µmol L-1 and the detection limit of this method was found to be 0.55 µmol L-1

  18. Microwave absorption properties of helical carbon nanofibers-coated carbon fibers

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2013-08-01

    Full Text Available Helical carbon nanofibers (HCNFs coated-carbon fibers (CFs were fabricated by catalytic chemical vapor deposition method. TEM and Raman spectroscopy characterizations indicate that the graphitic layers of the HCNFs changed from disorder to order after high temperature annealing. The electromagnetic parameters and microwave absorption properties were measured at 2–18 GHz. The maximum reflection loss is 32 dB at 9 GHz and the widest bandwidth under −10 dB is 9.8 GHz from 8.2 to 18 GHz for the unannealed HCNFs coated-CFs composite with 2.5 mm in thickness, suggesting that HCNFs coated-CFs should have potential applications in high performance microwave absorption materials.

  19. Self-heating function of carbon nanofiber cement pastes

    Directory of Open Access Journals (Sweden)

    Galao, O.

    2014-05-01

    Full Text Available The viability of carbon nanofiber (CNF composites incement matrices as a self-heating material is reported in this paper. This functional application would allow the use of CNF cement composites as a heating element in buildings, or for deicing pavements of civil engineering transport infrastructures, such as highways or airport runways. Cement pastes with the addition of different CNF dosages (from 0 to 5% by cement mass have been prepared. Afterwards, tests were run at different fixed voltages (50, 100 and 150V, and the temperature of the specimens was registered. Also the possibility of using a casting method like shotcrete, instead of just pouring the fresh mix into the mild (with no system’s efficiency loss expected was studied. Temperatures up to 138 °C were registered during shotcrete-5% CNF cement paste tests (showing initial 10 °C/min heating rates. However a minimum voltage was required in order to achieve a proper system functioning.En este artículo se estudia la viabilidad del uso de matrices cementicias con adición de nanofibras de carbono (NFC como elementos calefactores. Esto permitiría aumentar la temperatura de estancias en edificación o el deshielo de pavimentos en obras civiles. Se han fabricado pastas de cemento con distintas dosificaciones de NFC (0, 1, 2 y 5% respecto masa del cemento y sometidas al paso de corriente continua a distintos potenciales fijos (50, 100 y 150 V, mientras se controlaba la temperatura en distintos puntos. Se ha estudiado la viabilidad de utilizar la proyección de la pasta fresca como método de puesta en obra, sin perjudicar la eficiencia del sistema. Se consiguieron temperaturas de hasta 138 °C (con velocidades iniciales de 10 °C/min para pasta proyectada con 5% NFC. Además se ha detectado la necesidad de un potencial mínimo para que la densidad de corriente resultante sea suficiente para producir el efecto esperado.

  20. Surface analysis and electrochemistry of a robust carbon-nanofiber-based electrode platform H2O2 sensor

    Science.gov (United States)

    Suazo-Dávila, D.; Rivera-Meléndez, J.; Koehne, J.; Meyyappan, M.; Cabrera, C. R.

    2016-10-01

    A vertically aligned carbon nanofiber-based (VACNF) electrode platform was developed for an enzymeless hydrogen peroxide sensor. Vertical nanofibers have heights on the order of 2-3 μm, and diameters that vary from 50 to 100 nm as seen by atomic force microscopy. The VACNF was grown as individual, vertically, and freestanding structures using plasma-enhanced chemical vapor deposition. The electrochemical sensor, for the hydrogen peroxide measurement in solution, showed stability and reproducibility in five consecutive calibration curves with different hydrogen peroxide concentrations over a period of 3 days. The detection limit was 66 μM. The sensitivity for hydrogen peroxide electrochemical detection was 0.0906 mA cm-2 mM-1, respectively. The sensor was also used for the measurement of hydrogen peroxide as the by-product of the reaction of cholesterol with cholesterol oxidase as a biosensor application. The sensor exhibits linear behavior in the range of 50 μM-1 mM in cholesterol concentrations. The surface analysis and electrochemistry characterization is presented.

  1. Vapor-phase polymerization of poly(3, 4-ethylenedioxythiophene) nanofibers on carbon cloth as electrodes for flexible supercapacitors

    Science.gov (United States)

    Zhao, Xin; Dong, Mengyang; Zhang, Junxian; Li, Yingzhi; Zhang, Qinghua

    2016-09-01

    In this study, an evaporative vapor-phase polymerization approach was employed to fabricate vertically aligned poly(3, 4-ethylenedioxythiophene) (PEDOT) nanofibers on the surface of carbon cloth (CC). Optimized reaction conditions can obtain well distributed and uniform layers of high-aspect-ratio PEDOT nanofibers on CC. The hierarchical PEDOT/CC structure as a freestanding electrode exhibits good electrochemical properties. As a flexible symmetric supercapacitor, the PEDOT/CC hybrid electrode displays a specific areal capacitance of 201.4 mF cm-2 at 1 mA cm-2, good flexibility with a higher value (204.6 mF cm-2) in the bending state, and a good cycling stability of 92.4% after 1000 cycles. Moreover, the device shows a maximum energy density of 4.0 Wh kg-1 (with a power density of 3.2 kW kg-1) and a maximum power density of 4.2 kW kg-1 (with an energy density of 3.1 Wh kg-1). The results demonstrate that PEDOT may be a promising material for storage devices through a simple and efficient vapor-phase polymerization process with precisely controlled reaction conditions.

  2. Polyaniline nanofiber/large mesoporous carbon composites as electrode materials for supercapacitors

    Science.gov (United States)

    Liu, Huan; Xu, Bin; Jia, Mengqiu; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-01

    A composite of polyaniline nanofiber/large mesoporous carbon (PANI-F/LMC) hybrid was prepared by an in situ chemical oxidative polymerization of aniline monomer with nano-CaCO3 templated LMC as host matrix for supercapacitors. The morphology, composition and electronic structure of the composites (PANI-F/LMC) together with pure PANI nanofibers and the LMC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the PANI nanofibers were incorporated into the large mesochannels of LMC with interpenetrating framework formed. Such unique structure endows the PANI-F/LMC composite with a high capacitance of 473 F g-1 at a current load of 0.1 A g-1 with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  3. Using Mechanical Alloying to Create Bimetallic Catalysts for Vapor-Phase Carbon Nanofiber Synthesis

    Directory of Open Access Journals (Sweden)

    Laura Guevara

    2015-10-01

    Full Text Available Carbon nanofibers were generated over bimetallic catalysts in an atmospheric pressure chemical vapor deposition (APCVD reactor. Catalyst compositions of Fe 30 at%, Cu and Ni 30 at% and Cu were mechanically alloyed using high-energy ball milling over durations of 4, 8, 12, 16, and 20 h. The catalyst powders were then used to produce carbon nanofibers in ethylene and hydrogen (4:1 at temperatures of 500, 550, and 600 °C. The microstructures of the catalysts were characterized as a function of milling time as well as at deposition temperature. The corresponding carbon deposition rates were assessed and are correlated to the microstructural features of each catalyst. The milling process directly determines the performance of each catalyst toward carbon deposition, and both catalysts performed comparably to those made by traditional co-precipitation methods. Considerations in miscible and immiscible nanostructured alloy systems are discussed.

  4. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  5. Influence of oxygen on nitrogen-doped carbon nanofiber growth directly on nichrome foil

    Science.gov (United States)

    Vishwakarma, Riteshkumar; Shinde, Sachin M.; Saufi Rosmi, Mohamad; Takahashi, Chisato; Papon, Remi; Mahyavanshi, Rakesh D.; Ishii, Yosuke; Kawasaki, Shinji; Kalita, Golap; Tanemura, Masaki

    2016-09-01

    The synthesis of various nitrogen-doped (N-doped) carbon nanostructures has been significantly explored as an alternative material for energy storage and metal-free catalytic applications. Here, we reveal a direct growth technique of N-doped carbon nanofibers (CNFs) on flexible nichrome (NiCr) foil using melamine as a solid precursor. Highly reactive Cr plays a critical role in the nanofiber growth process on the metal alloy foil in an atmospheric pressure chemical vapor deposition (APCVD) process. Oxidation of Cr occurs in the presence of oxygen impurities, where Ni nanoparticles are formed on the surface and assist the growth of nanofibers. Energy-dispersive x-ray spectroscopy (EDXS) and x-ray photoelectron spectroscopy (XPS) clearly show the transformation process of the NiCr foil surface with annealing in the presence of oxygen impurities. The structural change of NiCr foil assists one-dimensional (1D) CNF growth, rather than the lateral two-dimensional (2D) growth. The incorporation of distinctive graphitic and pyridinic nitrogen in the graphene lattice are observed in the synthesized nanofiber, owing to better nitrogen solubility. Our finding shows an effective approach for the synthesis of highly N-doped carbon nanostructures directly on Cr-based metal alloys for various applications.

  6. Controlling growth of aligned carbon nanotubes from porous silicon templates

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Fabricating well-aligned carbon nanotubes, especially, on a silicon substrate is very important for their applications. In this paper, an aligned carbon nanotube array has been prepared by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles embedded in porous silicon (PS) templates. High-magnification transmission electron microscopy images confirm that the nanotubes are well graphitized. The PS substrates with pore sizes between 10 and 100 nm play a control role on the growth of carbon nanotubes and the diameters of the tubes increase with the enlargement of the pores of the substrates. However, such a control role cannot be found in the macro-PS substrates.

  7. Carbon nanofibers grafted on activated carbon as an electrode in high-power supercapacitors.

    Science.gov (United States)

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

    A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450 °C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium.

  8. Ion-assisted precursor dissociation and surface diffusion: Enabling rapid, low-temperature growth of carbon nanofibers

    Science.gov (United States)

    Denysenko, I.; Ostrikov, K.

    2007-06-01

    Growth kinetics of carbon nanofibers in a hydrocarbon plasma is studied. In addition to gas-phase and surface processes common to chemical vapor deposition, the model includes (unique to plasma-exposed catalyst surfaces) ion-induced dissociation of hydrocarbons, interaction of adsorbed species with incoming hydrogen atoms, and dissociation of hydrocarbon ions. It is shown that at low, nanodevice-friendly process temperatures the nanofibers grow via surface diffusion of carbon adatoms produced on the catalyst particle via ion-induced dissociation of a hydrocarbon precursor. These results explain a lower activation energy of nanofiber growth in a plasma and can be used for the synthesis of other nanoassemblies.

  9. Photocatalytic Oxidation of Volatile Organic Compounds Over Electrospun Activated TIO2/CARBON Nanofiber Composite

    Science.gov (United States)

    Gholamvand, Zahra; Aboutalebi, Seyed Hamed; Keyanpour-Rad, Mansoor

    In this study, TiO2/PAN-based fibers were prepared by electrospinning a composite solution containing both the desirable contents of TiO2 and a 10 wt. % PAN polymer solution dissolved in N, N-dimethylformamide. The TiO2 loaded electrospun PAN nanofibers were then carbonized at 1000 °C in N2 atmosphere furnace after stabilization at 230 °C in air. Then CNF/TiO2 nanofibers were oxidized at 450 °C in air. The morphology and structure of the TiO2-embeded carbon nanofibers were investigated by SEM and Raman spectroscopy. Specific surface area was determined using BET equation from N2 adsorption analysis. Photocatalytic tests were conducted in a UV illuminated set-up specialized for the filters using ethanol vapor. The results have shown that ethanol vapor was efficiently degraded on TiO2/CNF composite nanofiber mat under UV illumination. The aim of this study was to further investigate the feasibility of TiO2/ACF for practical indoor air purification.

  10. The Synthesis of Peculiar Structure of Springlike Multiwall Carbon Nanofibers/Nanotubes via Mechanothermal Method

    Directory of Open Access Journals (Sweden)

    Sahebali Manafi

    2012-01-01

    Full Text Available Mechanothermal (MT method is one of the methods used for large-scale production of carbon nanotubes/nanofibers. The different peculiar morphologies of carbon allotropes are introduced with an extraordinary structure for the first time by MT method. In this paper, the influence of milling time and annealing temperature on the crystallinity and morphology of the synthesized nanopowders was investigated. Surprisingly, in this investigation, we report the synthesis of springlike multiwalled carbon nanofibers (S-MWCNFs by a two-step annealing of milled graphite in an Ar atmosphere. On the other hand, the MT method could be used for the preparation of suitable structures with applications in nanocomposite materials, which is an important task in the era of nanotechnology.

  11. Aligning carbon fibers in micro-extruded composite ink

    Science.gov (United States)

    Mahajan, Chaitanya G.

    Direct write processes include a wide range of additive manufacturing techniques with the ability to fabricate structures directly onto planar and non-planar surfaces. Most additive manufacturing techniques use unreinforced polymers to produce parts. By adding carbon fiber as a reinforcing material, properties such as mechanical strength, electrical conductivity, and thermal conductivity can be enhanced. Carbon fibers can be long and continuous, or short and discontinuous. The strength of carbon fiber composite parts is greatly increased when the fibers are preferentially aligned. This research focuses on increasing the strength of additively manufactured parts reinforced using discontinuous carbon fibers that have been aligned during the micro extrusion process. A design of experiments (DOE) approach was used to identify significant process parameters affecting fiber alignment. Factors such as the length of carbon fibers, nozzle diameter, fiber loading fraction, air pressure, translational speed and standoff distance were considered. A two dimensional Fast Fourier Transform (2D FFT) was used to quantify the degree of fiber alignment in the extruded composite inks. ImageJ software supported by an oval profile plugin was used with micrographs of printed samples to obtain the carbon fiber alignment values. The optimal value for the factors was derived by identifying the significant main and interaction effects. Based on the results of the DOE, tensile test samples were printed with fibers aligned parallel and perpendicular to the tensile axis. A standard test method for tensile properties of plastic revealed that the extruded parts with fibers aligned along the tensile axis were better in tensile strength and modulus.

  12. Improved thermoplastic composite by alignment of vapor-grown carbon fiber

    Science.gov (United States)

    Kuriger, Rex Jerrald

    2000-10-01

    Vapor grown carbon fiber (VGCF) is a new and inexpensive carbon fiber produced by vapor deposition of hydrocarbons on metal catalysts. Unlike continuous conventional PAN or pitch-derived carbon fibers, VGCF is discontinuous with diameters of about 200 nanometers and lengths ranging from 10 to 200 micrometers. The microscopic size and random entanglement of the fibers create several problems when processing VGCF composites. It is particularly difficult to disperse the entangled fibers in the matrix and orient them along a preferred axis to provide directional reinforcement. This work introduces a technique to produce an improved polymeric composite by alignment of vapor grown carbon nano-fibers in a polypropylene matrix. A twin-screw extruder was used to shear mix and disperse the fibers in the polymer matrix. The composite mixtures were extruded through a converging-annular die that generates flow-induced fiber alignment along the extrusion direction. The effect that the various extrusion conditions have on the bulk properties of the extrudate was investigated. It was found that the extrusion process is strongly dependent on the fiber content of the composite. The extrusion pressure increased and the flow rate decreased with fiber volume fraction. The tensile strength and modulus for the composite samples varied with extrusion temperature and screw speed, and the void content increased with fiber volume fraction. It was shown that fiber alignment could be improved by increasing the residence time in the die channel and was verified using x-ray diffraction. The mechanical properties of the aligned samples increased with fiber content. Also, the tensile strength improved with greater fiber orientation; however, more fiber alignment had little affect on the modulus. To better predict the strength of these partially aligned fiber composites, an experimental and theoretical approach was introduced. The experimental data correspond reasonably well when compared with the

  13. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization

    Science.gov (United States)

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g−1 at 1.2 V in 500 mg l−1 NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  14. Collagen-biomorphic porous carbon nanofiber monoliths: Biosilicification-assisted sustainable synthesis and application in Li-S battery

    Science.gov (United States)

    Hu, Wen; Shen, Tao; Hou, Hongying; Gan, Guoyou; Zheng, Biju; Li, Fengxian; Yi, Jianhong

    2016-12-01

    Monolithic carbon has been synthesized via a sustainable biomimetic route utilizing intrafibrillar silicified collagen sponge as precursor and morphogenesis template. The mineralized silica in the biohybrid prevents collapse of the carbon during pyrolysis. Upon biosilica removal results show that the carbon monoliths inherit the porous fiber structure of the mother collagen. The carbon nanofiber framework facilitates the construction of a high electrical conductive pathway, while the internal spaces developed among the intertwined fibrillar network and pores within nanofiber walls offer room for sulfur storage. The as-obtained carbon-sulfur cathode exhibits an accessible discharge capacity approaching 800mAh g-1 in Li-S battery.

  15. Laccase Biosensor Based on Electrospun Copper/Carbon Composite Nanofibers for Catechol Detection

    Directory of Open Access Journals (Sweden)

    Jiapeng Fu

    2014-02-01

    Full Text Available The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs and copper/carbon composite nanofibers (Cu/CNFs. The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM, X-ray diffraction (XRD and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac/Nafion/glass carbon electrode (GCE possessed reliable analytical performance for the detection of catechol. The sensitivity of the Cu/CNFs/Lac/Nafion/GCE reached 33.1 μA/mM, larger than that of CNFs/Lac/Nafion/GCE. Meanwhile, Cu/CNFs/Lac/Nafion/GCE had a wider linear range from 9.95 × 10−6 to 9.76 × 10−3 M and a lower detection limit of 1.18 μM than CNFs/Lac/Nafion/GCE. Moreover, it exhibited a good repeatability, reproducibility, selectivity and long-term stability, revealing that electrospun Cu/CNFs have great potential in biosensing.

  16. Laccase Biosensor Based on Electrospun Copper/Carbon Composite Nanofibers for Catechol Detection

    Science.gov (United States)

    Fu, Jiapeng; Qiao, Hui; Li, Dawei; Luo, Lei; Chen, Ke; Wei, Qufu

    2014-01-01

    The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac)/Nafion/glass carbon electrode (GCE) possessed reliable analytical performance for the detection of catechol. The sensitivity of the Cu/CNFs/Lac/Nafion/GCE reached 33.1 μA/mM, larger than that of CNFs/Lac/Nafion/GCE. Meanwhile, Cu/CNFs/Lac/Nafion/GCE had a wider linear range from 9.95 × 10−6 to 9.76 × 10−3 M and a lower detection limit of 1.18 μM than CNFs/Lac/Nafion/GCE. Moreover, it exhibited a good repeatability, reproducibility, selectivity and long-term stability, revealing that electrospun Cu/CNFs have great potential in biosensing. PMID:24561403

  17. Performance of electrodes synthesized with polyacrylonitrile-based carbon nanofibers for application in electrochemical sensors and biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Adabi, Mahdi [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Saber, Reza [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridi-Majidi, Reza, E-mail: refaridi@sina.tums.ac.ir [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridbod, Farnoush [Science and Technology in Medicine (RCSTIM), Tehran University of Medical Sciences, Tehran, Iran. (Iran, Islamic Republic of)

    2015-03-01

    The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased. - Highlights: • Electrospun CNFs can be directly used as working electrode. • Cyclic voltammetric response improved as diameter of CNFs electrode decreased. • The diameter of nanofibers reduced with decreasing polymer concentration. • The diameter of nanofibers reduced with decreasing applied voltage. • The diameter of nanofibers reduced with increasing tip-to-collector distance.

  18. Preparation of flexible zinc oxide/carbon nanofiber webs for mid-temperature desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soojung; Bajaj, Bharat [Carbon Convergence Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101, Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do 565-905 (Korea, Republic of); Byun, Chang Ki; Kwon, Soon-Jin [Department of Chemical Engineering Education, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Joh, Han-Ik [Carbon Convergence Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101, Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do 565-905 (Korea, Republic of); Yi, Kwang Bok, E-mail: cosy32@cnu.ac.kr [Department of Chemical Engineering Education, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Lee, Sungho, E-mail: sunghol@kist.re.kr [Carbon Convergence Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101, Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do 565-905 (Korea, Republic of); Department of Nano Material Engineering, University of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2014-11-30

    Graphical abstract: - Highlights: • Polyacrylonitrile (PAN) and zinc precursor were electrospun and heat-treated for preparing zinc oxide (ZnO) modified carbon nanofibers (CNF). • A facile synthesis of composite webs resulted in uniformly loaded ZnO on the surface of CNFs. • The composites showed significant hydrogen sulfide adsorption efficiency at 300 °C. • The flexible webs can be applied for mid-temperature desulfurization. - Abstract: Polyacrylonitrile (PAN) derived carbon nanofiber (CNF) webs loaded with zinc oxide (ZnO) were synthesized using electrospinning and heat treatment at 600 °C. Uniformly dispersed ZnO nanoparticles, clarified by X-ray diffraction and scanning electron microscopy, were observed on the surface of the nanofiber composites containing 13.6–29.5 wt% of ZnO. The further addition of ZnO up to 34.2 wt% caused agglomeration with a size of 50–80 nm. Higher ZnO contents led the concentrated ZnO nanoparticles on the surface of the nanofibers rather than uniform dispersion along the cross-section of the fiber. The flexible composite webs were crushed and tested for hydrogen sulfide (H{sub 2}S) adsorption at 300 °C. Breakthrough experiments with the ZnO/CNF composite containing 25.7 wt% of ZnO for H{sub 2}S adsorption showed three times higher ZnO utilization efficiency compared to pure ZnO nano powders, attributed to chemisorption of the larger surface area of well dispersed ZnO particles on nanofibers and physical adsorption of CNF.

  19. Thermoelectric Properties of Carbon Nanotube and Nanofiber Based Ethylene-Octene Copolymer Composites for Thermoelectric Devices

    Directory of Open Access Journals (Sweden)

    P. Slobodian

    2013-01-01

    Full Text Available Polymer composites have been created from multiwalled carbon nanotubes or carbon nanofibers and ethylene-octene copolymer. The composites have thermoelectric properties and exhibit thermoelectric effect, that is, the conversion of temperature differences into electricity. The thermoelectric efficiency of created composites with nanotube or nanofiber concentration of 30 wt% evaluated by a thermoelectric power at room temperature is 13.3 μV/K and 14.2 μV/K, respectively. The flexible thermoelectric device (thermopile was constructed with three different composite legs to produce electric current and the output voltage was measured in the range of temperature difference from −15 to 25°C.

  20. A novel rotary reactor configuration for simultaneous production of hydrogen and carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Pinilla, J.L.; Utrilla, R.; Lazaro, M.J.; Suelves, I.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma 4, 50018 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica CSIC, Cantoblanco, Marie Curie 2, 28049-Madrid (Spain)

    2009-10-15

    A novel reactor configuration, a rotary bed reactor (RBR), was used to study at large scale production the Catalytic Decomposition of Methane (CDM) into hydrogen and carbon nanofibers using a nickel-copper catalyst. The results were compared to those obtained in a fluidized bed reactor (FBR) under the same operating conditions. Tests carried out in the RBR provided higher hydrogen yields and more sustainable catalyst performance in comparison to the FBR. Additionally, the effect of the rotation speed and reaction temperature on the performance in the RBR of the nickel-copper catalyst was studied. The textural and structural properties of the carbon nanofibers produced were also studied by means of N{sub 2} adsorption, SEM and XRD, and compared to those obtained in the FBR set-up under the same operating conditions. (author)

  1. Effects of vapor grown carbon nanofibers on electrical and mechanical properties of a thermoplastic elastomer

    Science.gov (United States)

    Basaldua, Daniel Thomas

    Carbon nanofiber (CNF) reinforced composites are exceptional materials that exhibit superior properties compared to conventional composites. This paper presents the development of a vapor grown carbon nanofiber (VGCNF) thermoplastic polyurethane (TPU) composite by a melt mixing process. Dispersion and distribution of CNFs inside the TPU matrix were examined through scanning electron microscopy to determine homogeneity. The composite material underwent durometer, thermal gravimetric analysis, differential scanning calorimetry, heat transfer, hysteresis, dynamic modulus, creep, tensile, abrasion, and electrical conductivity testing to characterize its properties and predict behavior. The motivation for this research is to develop an elastomer pad that is an electrically conductive alternative to the elastomer pads currently used in railroad service. The material had to be a completely homogenous electrically conductive CNF composite that could withstand a harsh dynamically loaded environment. The new material meets mechanical and conductive requirements for use as an elastomer pad in a rail suspension.

  2. Self-floating graphitic carbon nitride/zinc phthalocyanine nanofibers for photocatalytic degradation of contaminants.

    Science.gov (United States)

    Xu, Tiefeng; Ni, Dongjing; Chen, Xia; Wu, Fei; Ge, Pengfei; Lu, Wangyang; Hu, Hongguang; Zhu, ZheXin; Chen, Wenxing

    2016-11-05

    The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C3N4/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C3N4/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C3N4/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules.

  3. Carbon nanofibers, precious commodities from sunlight & CO2 to ameliorate global warming

    CERN Document Server

    Licht, Stuart

    2015-01-01

    This study introduces the high yield, electrolytic synthesis of carbon nanofibers, CNFs, directly from carbon dioxide. Production of a precious commodity such as CNFs from atmospheric carbon dioxide provides impetus to limit this greenhouse gas and mitigate the rate of climate change. CNFs are formed at high rate using inexpensive nickel and steel electrodes in molten electrolytes. The process is demonstrated as a scaled-up stand-alone electrolytic cell, and is also shown compatible with the STEP, solar thermal electrochemical process, using concentrated sunlight at high solar to electric efficiency to provide the heat and electrical energy to drive the CNF production.

  4. IR study on surface chemical properties of catalytic grown carbon nanotubes and nanofibers

    Institute of Scientific and Technical Information of China (English)

    Li-hua TENG; Tian-di TANG

    2008-01-01

    In this study, the surface chemical properties of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) grown by catalytic decomposition of methane on nickel and cobalt based catalysts were studied by DRIFT (Diffuse Reflectance Infrared Fourier Transform) and transmission Infrared (IR) spectroscopy. The results show that the surface exists not only carbon-hydrogen groups, but also carboxyl, ketene or quinone (carbonyl) oxygen-containing groups. These functional groups were formed in the process of the material growth, which result in large amount of chemical defect sites on the walls.

  5. Novel catalytic applications of carbon nanofibers on sintered metal fibers filters as structured supports

    OpenAIRE

    2009-01-01

    Supported metal catalysts are important from both an industrial and a scientific point of view. They are used, amongst others, in large-scale processes such as catalytic reforming, hydrotreating, polymerization reactions and hydrogenations. Often, these catalysts consist of nanosized metal particles deposited on a suitable support, which acts as an anchor for the active phase and, in several cases, contributes to improve the overall catalyst performances. The growth of carbon nanofibers on si...

  6. Novel catalytic applications of carbon nanofibers on sintered metal fibers filters as structured supports

    OpenAIRE

    2008-01-01

    Supported metal catalysts are important from both an industrial and a scientific point of view. They are used, amongst others, in large-scale processes such as catalytic reforming, hydrotreating, polymerization reactions and hydrogenations. Often, these catalysts consist of nanosized metal particles deposited on a suitable support, which acts as an anchor for the active phase and, in several cases, contributes to improve the overall catalyst performances. The growth of carbon nanofibers on si...

  7. Porosity and fractal study of functionalized carbon nanofibers: Effects of the functionalization degree on hydrogen storage capacity

    Science.gov (United States)

    Galindo-Hernández, Félix; Portales, Benjamín; Domínguez, José M.; Angeles-Beltrán, Deyanira

    2014-12-01

    Carbon nanofibers are produced by siliceous SBA-15 type materials and the casting method. The nanofibers are functionalized by HNO3 attack in aqueous phase under microwave radiation. N2 sorption data are treated by Non-Local Density Functional Theory and Quenched Solid Density Functional Theory to determine advanced adsorption among other textural properties. The functionalization degree of carbon nanofibers and their hydrogen storage capacity are mainly investigated by FTIR spectroscopy, capacitance studies and analysis of the fractal dimension of the surface. This latter in two ways: i) using the Neimark-Kiselev equation with N2 sorption data and ii) using Box-counting, Information and Perimeter-area methods on TEM photomicrographs. The hydrogen storage testing reveals that functionalized carbon nanofibers adsorb hydrogen above 200% with respect to unfunctionalized carbon nanofibers. This effect is attributed to: i) the creation of extra spacing between contiguous nanofibers, as a consequence of mutual repulsion between the -COOH groups and ii) increase of volume intrawall.

  8. Synthesis of Aligned Carbon Nanotubes by Thermal Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHOU Ming; MA Weiwei; CAI Lan

    2009-01-01

    Single crystal silicon was found to be very beneficial to the growth of aligned carbon nanotubes by chemical vapor deposition with C2H2 as carbon source. A thin film of Ni served as catalyst was deposited on the Si substrate by the K575X Peltier Cooled High Resolution Sputter Coater before growth. The growth properties of carbon nanotubes were studied as a function of the Ni catalyst layer thickness. The diameter, growth rate and areal density of the carbon nanotubes were controlled by the initial thickness of the catalyst layer. Steric hindrance between nanotubes forces them to grow in well-aligned manner at an initial stage of growth. Transmission electron microscope analysis revealed that nanotubes grew by a tip growth mechanism.

  9. Spectroscopic studies of the influence of CNTs on the thermal conversion of PAN fibrous membranes to carbon nanofibers

    Science.gov (United States)

    Stodolak-Zych, E.; Benko, A.; Szatkowski, P.; Długoń, E.; Nocuń, M.; Paluszkiewicz, C.; Błażewicz, M.

    2016-12-01

    Structural changes accompanying stabilization and carbonization processes of the two types of polyacrylonitrile (PAN) nanofiber precursors (pure PAN and PAN with carbon nanotubes) were studied using infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The fibrous membranes were preliminary stabilized in air followed by the two-step carbonization process under nitrogen atmosphere. IR absorption spectra showed that the introduction of a small amount of functionalized multiwall carbon nanotubes (MWCNT) into the PAN precursor has a significant impact on its stabilization process. Raman spectroscopy study showed that the structure of carbon nanofibers containing CNT is distinctly more ordered in comparison to pure carbon nanofibers. Based on the XPS analysis the concentration of heteroatoms and the type and amount of functional groups on the surfaces of both types of nanofibers were determined. The results indicate a high potential of functionalized MWCNT as a pyrolysis modifier of polymer precursor leading to the formation of carbon nanofibers with controlled structure and defined chemical state of the surface.

  10. Broadband laser polarization control with aligned carbon nanotubes

    CERN Document Server

    Yang, He; Lia, Diao; Chen, Ya; Mattila, Marco; Tian, Ying; Yong, Zhenzhong; Yang, Changxi; Tittonen, Ilkka; Ren, Zhaoyu; Bai, Jingtao; Li, Qingwen; Kauppinen, Esko I; Lipsanen, Harri; Sun, Zhipei

    2015-01-01

    We introduce a simple approach to fabricate aligned carbon nanotube (ACNT) device for broadband polarization control in fiber laser systems. The ACNT device was fabricated by pulling from as-fabricated vertically-aligned carbon nanotube arrays. Their anisotropic property is confirmed with optical and scanning electron microscopy, and with polarized Raman and absorption spectroscopy. The device was then integrated into fiber laser systems (at two technologically important wavelengths of 1 and 1.5 um) for polarization control. We obtained a linearly-polarized light output with the maximum extinction ratio of ~12 dB. The output polarization direction could be fully controlled by the ACNT alignment direction in both lasers. To the best of our knowledge, this is the first time that ACNT device is applied to polarization control in laser systems. Our results exhibit that the ACNT device is a simple, low-cost, and broadband polarizer to control laser polarization dynamics, for various photonic applications (such as ...

  11. Improvement of the electrical conductivity of carbon fibers through the growth of carbon nanofibers.

    Science.gov (United States)

    Moon, Cheol-Whan; Meng, Long-Yue; Im, Seung-Soon; Rhee, Kyong-Yop; Park, Soo-Jin

    2011-07-01

    In this work, carbon nanofibers (CNFs) were synthesized on carbon fiber (CF) surfaces precoated with metal-doped mesoporous silica films. Fe, Ni, and Co were doped in the mesoporous silica films and played the role of catalysts for the decomposition of acetylene to grow CNFs on the CF surfaces. The chemical composition and surface structure of CFs before and after the growth of the CNFs were investigated by EDX, N2 full isotherms, and SEM. The electrical property of the CFs was investigated using a four-probe volume resistivity tester. The SEM results indicated that the CNFs with diameters of 20-100 nm grew uniformly and densely on the CF surfaces. The diameter and length distributions of the CNFs were found to be dependent on the metal that was doped in the mesoporous silica films. The electrical properties of the CFs were enhanced after the CNFs' growth on the CF surfaces, and the CNFs grown over the Ni catalyst with the narrowest diameter distribution gave the lowest volume resistivity to the CFs.

  12. Increased Alignment in Carbon Nanotube Growth

    Science.gov (United States)

    Delzeit, Lance D. (Inventor)

    2007-01-01

    Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

  13. Surface analysis and electrochemistry of a robust carbon-nanofiber-based electrode platform H{sub 2}O{sub 2} sensor

    Energy Technology Data Exchange (ETDEWEB)

    Suazo-Dávila, D.; Rivera-Meléndez, J. [NASA-MIRO Center for Advanced Nanoscale Materials (CANM), Department of Chemistry, Molecular Sciences Research Center, University of Puerto Rico, Río Piedras Campus, San Juan, PR, 00936 (United States); Koehne, J.; Meyyappan, M. [Center for Nanotechnology, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Cabrera, C.R., E-mail: carlos.cabrera2@upr.edu [NASA-MIRO Center for Advanced Nanoscale Materials (CANM), Department of Chemistry, Molecular Sciences Research Center, University of Puerto Rico, Río Piedras Campus, San Juan, PR, 00936 (United States)

    2016-10-30

    Highlights: • Vertically aligned carbon nanofibers were intercalated with SiO{sub 2} for mechanical strength and isolation of individual electrodes. • Stable and robust electrochemical hydrogen peroxide sensor is stable and robust. • Five consecutive calibration curves were done with different hydrogen peroxide concentrations over a period of 3 days without any deterioration in the electrochemical response. • The sensor was also used for the measurement of hydrogen peroxide as one of the by-products of the reaction of cholesterol oxidase with cholesterol and the sensor response exhibited linear behavior from 50 μM to 1 mM in cholesterol concentration. • In general, the electrochemical sensor is robust, stable, and reproducible, and the detection limit and sensitivity responses were among the best when compared with the literature. - Abstract: A vertically aligned carbon nanofiber-based (VACNF) electrode platform was developed for an enzymeless hydrogen peroxide sensor. Vertical nanofibers have heights on the order of 2–3 μm, and diameters that vary from 50 to 100 nm as seen by atomic force microscopy. The VACNF was grown as individual, vertically, and freestanding structures using plasma-enhanced chemical vapor deposition. The electrochemical sensor, for the hydrogen peroxide measurement in solution, showed stability and reproducibility in five consecutive calibration curves with different hydrogen peroxide concentrations over a period of 3 days. The detection limit was 66 μM. The sensitivity for hydrogen peroxide electrochemical detection was 0.0906 mA cm{sup −2} mM{sup −1}, respectively. The sensor was also used for the measurement of hydrogen peroxide as the by-product of the reaction of cholesterol with cholesterol oxidase as a biosensor application. The sensor exhibits linear behavior in the range of 50 μM–1 mM in cholesterol concentrations. The surface analysis and electrochemistry characterization is presented.

  14. Preparation and electrochemical properties of carbon-coated LiFePO4 hollow nanofibers

    Institute of Scientific and Technical Information of China (English)

    Bin-bin Wei; Yan-bo Wu; Fang-yuan Yu; Ya-nan Zhou

    2016-01-01

    Carbon-coated LiFePO4 hollow nanofibers as cathode materials for Li-ion batteries were obtained by coaxial electrospinning. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) were employed to investigate the crystalline structure, morphology, and electrochemical performance of the as-prepared hollow nanofibers. The results indicate that the carbon-coated LiFePO4 hollow nanofibers have good long-term cycling performance and good rate capability:at a current density of 0.2C (1.0C=170 mA·g−1) in the voltage range of 2.5–4.2 V, the cathode materials achieve an initial discharge specific capacity of 153.16 mAh·g−1 with a first charge–discharge coulombic efficiency of more than 97%, as well as a high capacity retention of 99%after 10 cycles;moreover, the materi-als can retain a specific capacity of 135.68 mAh·g−1, even at 2C.

  15. Preparation and electrochemical properties of carbon-coated LiFePO4 hollow nanofibers

    Science.gov (United States)

    Wei, Bin-bin; Wu, Yan-bo; Yu, Fang-yuan; Zhou, Ya-nan

    2016-04-01

    Carbon-coated LiFePO4 hollow nanofibers as cathode materials for Li-ion batteries were obtained by coaxial electrospinning. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller specific surface area analysis, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) were employed to investigate the crystalline structure, morphology, and electrochemical performance of the as-prepared hollow nanofibers. The results indicate that the carbon-coated LiFePO4 hollow nanofibers have good long-term cycling performance and good rate capability: at a current density of 0.2C (1.0C = 170 mA·g-1) in the voltage range of 2.5-4.2 V, the cathode materials achieve an initial discharge specific capacity of 153.16 mAh·g-1 with a first charge-discharge coulombic efficiency of more than 97%, as well as a high capacity retention of 99% after 10 cycles; moreover, the materials can retain a specific capacity of 135.68 mAh·g-1, even at 2C.

  16. Silicon-Encapsulated Hollow Carbon Nanofiber Networks as Binder-Free Anodes for Lithium Ion Battery

    Directory of Open Access Journals (Sweden)

    Ding Nan

    2014-01-01

    Full Text Available Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder-free anodes for Li-ion batteries (LIBs. In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high-performance LIBs.

  17. Antitumor Activity of Doxorubicin-Loaded Carbon Nanotubes Incorporated Poly(Lactic-Co-Glycolic Acid) Electrospun Composite Nanofibers

    Science.gov (United States)

    Yu, Yuan; Kong, Lijun; Li, Lan; Li, Naie; Yan, Peng

    2015-08-01

    The drug-loaded composite electrospun nanofiber has attracted more attention in biomedical field, especially in cancer therapy. In this study, a composite nanofiber was fabricated by electrospinning for cancer treatment. Firstly, the carbon nanotubes (CNTs) were selected as carriers to load the anticancer drug—doxorubicin (DOX) hydrochloride. Secondly, the DOX-loaded CNTs (DOX@CNTs) were incorporated into the poly(lactic-co-glycolic acid) (PLGA) nanofibers via electrospinning. Finally, a new drug-loaded nanofibrous scaffold (PLGA/DOX@CNTs) was formed. The properties of the prepared composite nanofibrous mats were characterized by various techniques. The release profiles of the different DOX-loaded nanofibers were measured, and the in vitro antitumor efficacy against HeLa cells was also evaluated. The results showed that DOX-loaded CNTs can be readily incorporated into the nanofibers with relatively uniform distribution within the nanofibers. More importantly, the drug from the composite nanofibers can be released in a sustained and prolonged manner, and thereby, a significant antitumor efficacy in vitro is obtained. Thus, the prepared composite nanofibrous mats are a promising alternative for cancer treatment.

  18. Effect of Carbon Nanofiber Heat Treatment on Physical Properties of Polymeric Nanocomposites—Part I

    Directory of Open Access Journals (Sweden)

    Khalid Lafdi

    2007-01-01

    Full Text Available The definition of a nanocomposite material has broadened significantly to encompass a large variety of systems made of dissimilar components and mixed at the nanometer scale. The properties of nanocomposite materials also depend on the morphology, crystallinity, and interfacial characteristics of the individual constituents. In the current work, vapor-grown carbon nanofibers were subjected to varying heat-treatment temperatures. The strength of adhesion between the nanofiber and an epoxy (thermoset matrix was characterized by the flexural strength and modulus. Heat treatment to 1800C∘ demonstrated maximum improvement in mechanical properties over that of the neat resin, while heat-treatment to higher temperatures demonstrated a slight decrease in mechanical properties likely due to the elimination of potential bonding sites caused by the elimination of the truncated edges of the graphene layers. Both the electrical and thermal properties of the resulting nanocomposites increased in conjunction with the increasing heat-treatment temperature.

  19. Advanced Multifunctional Properties of Aligned Carbon Nanotube-Epoxy Composites from Carbon Nanotube Aerogel Method

    Science.gov (United States)

    Tran, Thang; Liu, Peng; Fan, Zeng; Ngern, Nigel; Duong, Hai

    2015-03-01

    Unlike previous methods of making carbon nanotube (CNT) thin films, aligned CNT thin films in this work are synthesized directly from CNT aerogels in a CVD process. CH4/H2/He gases and ferrocene/thiophene catalysts are mixed and reacted in the reactor at 1200 °C to form CNT aerogel socks. By pulling out the socks with a metal rod, CNT thin films with 15-nm diameter MWNTs are aligned and produced continuously at a speed of a few meters per minute. The number of the aligned CNT thin film layers/ thickness can also be controlled well. The as-synthesized aligned CNT films are further condensed by acetone spray and post-treated by UV light. The aligned CNT films without any above post-treatment have a high electrical conductivity of 400S/cm. We also develop aligned CNT-epoxy composites by infiltrating epoxy into the above aligned CNT thin films using Vacuum Assisted Resin Transfer Molding (VARTM) method. Our cost-effective fabrication method of the aligned CNT films is more advanced for developing the composites having CNT orientation control. The mechanical, electrical and optical properties of the aligned CNT epoxy composites are measured. About 2% of the aligned CNTs can enhance significantly the electrical conductivity and hardness of aligned CNT-epoxy composite films. Effects of morphologies, volume fraction, and alignment of the CNTs on the advanced multifunctional properties of the aligned CNT-epoxy composites are also quantified.

  20. A high performance silicon/carbon composite anode with carbon nanofiber for lithium-ion batteries

    Science.gov (United States)

    Si, Q.; Hanai, K.; Ichikawa, T.; Hirano, A.; Imanishi, N.; Takeda, Y.; Yamamoto, O.

    The electrochemical performance of a composite of nano-Si powder and a pyrolytic carbon of polyvinyl chloride (PVC) with carbon nanofiber (CNF) was examined as an anode for lithium-ion batteries. CNF was incorporated into the composite by two methods; direct mixing of CNF with the nano-Si powder coated with carbon produced by pyrolysis of PVC (referred to as Si/C/CNF-1) and mixing of CNF, nano-Si powder, and PVC with subsequent firing (referred to as Si/C/CNF-2). The external Brunauer-Emmett-Teller (BET) surface area of Si/C/CNF-1 was comparable to that of Si/C/CNF-2. The micropore BET surface area of Si/C/CNF-2 (73.86 m 2 g -1) was extremely higher than that of Si/C/CNF-1 (0.74 m 2 g -1). The composites prepared by both methods exhibited high capacity and excellent cycling stability for lithium insertion and extraction. A capacity of more than 900 mA h g -1 was maintained after 30 cycles. The coulombic efficiency of the first cycle for Si/C/CNF-1 was as low as 53%, compared with 73% for Si/C/CNF-2. Impedance analysis of cells containing these anode materials suggested that the charge transfer resistance for Si/C/CNF-1 was not changed by cycling, but that Si/C/CNF-2 had high charge transfer resistance after cycling. A composite electrode prepared by mixing Si/C/CNF-2 and CNF exhibited a high reversible capacity at high rate, excellent cycling performance, and a high coulombic efficiency during the first lithium insertion and extraction cycles.

  1. Effective combination of aligned nanocomposite nanofibers and human unrestricted somatic stem cells for bone tissue engineering

    Institute of Scientific and Technical Information of China (English)

    Behnaz BAKHSHANDEH; Masoud SOLEIMANI; Nasser GHAEMI; Iman SHABANI

    2011-01-01

    Aim: Bioartificial bone tissue engineering is an increasingly popular technique to solve bone defect challenges. This study aimed to investigate the interactions between matrix composition and appropriate cell type, focusing on hydroxyapatite (HA), to achieve a more effective combination for bone regeneration.Methods: Human unrestricted somatic stem cells (USSCs) were isolated from placental cord blood. The cellular and molecular events during the osteo-induction of USSCs were evaluated for 21 d under the following conditions: (1) in basal culture, (2) supplemented with hydroxyapatite nanoparticle (nHA) suspension, and (3) seeded on electrospun aligned nanoflbrous poly-ε-caprolactone/poly-L-lactic acid/nHA (PCL/PLLA/nHA) scaffolds. The scaffolds were characterized using scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR) and tensile test.Results: Maintenance of USSCs for 21 d in basal or osteogenic culture resulted in significant increase in osteoblast differentiation. With nHA suspension, even soluble osteo-inductive additives were ineffective, probably due to induced apoptosis of the cells. In con-trast to the hindrance of proliferation by nHA suspension, the scaffolds improved cell growth. The scaffolds mimic the nanostructure of natural bone matrix with the combination of PLLA/PCL (organic phase) and HA (inorganic phase) offering a favorable surface topogra-phy, which was demonstrated to possess suitable properties for supporting USSCs. Quantitative measurement of osteogenic markers, enzymatic activity and mineralization indicated that the scaffolds did not disturb, but enhanced the osteogenic potential of USSCs.Moreover, the alignment of the fibers led to cell orientation during cell growth.Conclusion: The results demonstrated the synergism of PCL/PLLA/nHA nanoflbrous scaffolds and USSCs in the augmentation of osteo-genic differentiation. Thus, nHA grafted into PCI./PLLA scaffolds can be a suitable choice for bone tissue

  2. Electrospun La0.8Sr0.2MnO3 nanofibers for a high-temperature electrochemical carbon monoxide sensor

    Science.gov (United States)

    Zhi, Mingjia; Koneru, Anveeksh; Yang, Feng; Manivannan, Ayyakkannu; Li, Jing; Wu, Nianqiang

    2012-08-01

    Lanthanum strontium manganite (La0.8Sr0.2MnO3, LSM) nanofibers have been synthesized by the electrospinning method. The electrospun nanofibers are intact without morphological and structural changes after annealing at 1050 °C. The LSM nanofibers are employed as the sensing electrode of an electrochemical sensor with yttria-stabilized zirconia (YSZ) electrolyte for carbon monoxide detection at high temperatures over 500 °C. The electrospun nanofibers form a porous network electrode, which provides a continuous pathway for charge transport. In addition, the nanofibers possess a higher specific surface area than conventional micron-sized powders. As a result, the nanofiber electrode exhibits a higher electromotive force and better electro-catalytic activity toward CO oxidation. Therefore, the sensor with the nanofiber electrode shows a higher sensitivity, lower limit of detection and faster response to CO than a sensor with a powder electrode.

  3. Metal nanoparticle-directed NiCo2O4 nanostructure growth on carbon nanofibers with high capacitance.

    Science.gov (United States)

    Chen, Long; Zhu, Jiahua

    2014-08-04

    Metal nanoparticles (Ni, Co) decorated on an electrospun carbon nanofiber surface directed the growth of NiCo2O4 into nanorod and nanosheet morphologies. These metal nanoparticles served as a transition layer to strengthen the interface and promote charge transfer between carbon and NiCo2O4 to achieve a high capacitance of 781 F g(-1).

  4. Alignment and Load Transfer in Carbon Nanotube and Dicyclopentadiene Composites

    Science.gov (United States)

    Severino, Joseph Vincent

    Individual carbon nanotubes (CNTs) are the strongest materials available but their macroscopic assemblies are weak. This work establishes a new thermosetting dicyclopentadiene (DCPD) and CNT composite that increases the strength of CNT assemblies. These high volume fraction and void free structures constitute advanced materials that could one day replace traditional composite systems. To further the understanding of physical interactions between polymer and CNTs, a novel "capstan" load transfer mechanism is also introduced. Self-supporting assemblies of interconnected carbon nanotubes were stretched, twisted and compressed to fashion composites by the infusion and polymerization of low viscosity DCPD based monomeric resins. The properties of the CNTs, polymer and composite were characterized with thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA) and Raman spectroscopy. The microstructure was analyzed by wide angle X-ray scattering (WAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Sheets were drawn at 15 m/min from a growth furnace to impart alignment then stretched to further modify alignment. The mechanical properties were determined in five orientations with respect to the growth direction. The strength was nearly three times higher along this growth direction than it was perpendicular, and modulus was nearly six times higher. Transverse stretching achieved 1.5 times the elongation but alignment was inferior due to CNT kinking that prevented alignment and consolidation. Composites yarns and sheets were investigated for the mechanical properties, microstructure and load transfer. The DCPD resin was found to wet the CNTs and lubricated deformation. This reduced loads during processing, and curing solidified the aligned and consolidated structure. The stretched and twisted composite yarns increased the failure stress 51%. In aligned composite sheet, the failure stress increased 200%. The increased stresses

  5. Control of physical properties of carbon nanofibers obtained from coaxial electrospinning of PMMA and PAN with adjustable inner/outer nozzle-ends.

    Science.gov (United States)

    Kaerkitcha, Navaporn; Chuangchote, Surawut; Sagawa, Takashi

    2016-12-01

    Hollow carbon nanofibers (HCNFs) were prepared by electrospinning method with several coaxial nozzles, in which the level of the inner nozzle-end is adjustable. Core/shell nanofibers were prepared from poly(methyl methacrylate) (PMMA) as a pyrolytic core and polyacrylonitrile (PAN) as a carbon shell with three types of normal (viz. inner and outer nozzle-ends are balanced in the same level), inward, and outward coaxial nozzles. The influence of the applied voltage on these three types of coaxial nozzles was studied. Specific surface area, pore size diameter, crystallinity, and degree of graphitization of the hollow and mesoporous structures of carbon nanofibers obtained after carbonization of the as spun PMMA/PAN nanofibers were characterized by BET analyses, X-ray diffraction, and Raman spectroscopy in addition to the conductivity measurements. It was found that specific surface area, crystallinity, and graphitization degree of the HCNFs affect the electrical conductivity of the carbon nanofibers.

  6. Cleavage of catalytic ally grown carbon nanofibers into hydrophilic segments by oxidation in a mixture of concentrated HNO3-H2SO4 in an autoclave

    Institute of Scientific and Technical Information of China (English)

    TENG Li-hua; WANG Zhi-jiang; TANG Tian-di

    2012-01-01

    The catalytically grown carbon nanofibers were treated by a mixture of concentrated nitric aid and sulfuric aid in an autoclave at temperature 333,363 and 423 K.It was found that the samples treated at 363 K and 423 K were still well dispersed in water 15 hours later,indicating that carbon nanofibers can be made hydrophilicy.It was also found that the dispersion was destroyed when the pH value was lowered by adding acid.The results are significant when the carbon nanofibers are used as enhancing component in polymer composite material because several hundreds of nm are perfect size and the hydrophilicity controls the dispersion of CNFs in the polymer media.It is concluded that the amount of the oxygen-containing groups on the surface and the hydrophilicity of the carbon nanofibers can be controlled by the treatment temperature,and that the carbon nanofibers can be cleaved into uniform segments.

  7. Multi-scale carbon micro/nanofibers-based adsorbents for protein immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shiv; Singh, Abhinav [Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Bais, Vaibhav Sushil Singh; Prakash, Balaji [Department of Biological Science and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Verma, Nishith, E-mail: nishith@iitk.ac.in [Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Center for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2014-05-01

    In the present study, different proteins, namely, bovine serum albumin (BSA), glucose oxidase (GOx) and the laboratory purified YqeH were immobilized in the phenolic resin precursor-based multi-scale web of activated carbon microfibers (ACFs) and carbon nanofibers (CNFs). These biomolecules are characteristically different from each other, having different structure, number of parent amino acid molecules and isoelectric point. CNF was grown on ACF substrate by chemical vapor deposition, using Ni nanoparticles (Nps) as the catalyst. The ultra-sonication of the CNFs was carried out in acidic medium to remove Ni Nps from the tip of the CNFs to provide additional active sites for adsorption. The prepared material was directly used as an adsorbent for proteins, without requiring any additional treatment. Several analytical techniques were used to characterize the prepared materials, including scanning electron microscopy, Fourier transform infrared spectroscopy, BET surface area, pore-size distribution, and UV–vis spectroscopy. The adsorption capacities of prepared ACFs/CNFs in this study were determined to be approximately 191, 39 and 70 mg/g for BSA, GOx and YqeH, respectively, revealing that the carbon micro-nanofibers forming synthesized multi-scale web are efficient materials for the immobilization of protein molecules. - Highlights: • Ni metal Np-dispersed carbon micro-nanofibers (ACFs/CNFs) are prepared. • ACFs/CNFs are mesoporous. • Significant adsorption of BSA, GOx and YqeH is observed on ACFs/CNFs. • Multi-scale web of ACFs/CNFs is effective for protein immobilization.

  8. Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Evora, M.C., E-mail: cecilia@ieav.cta.br [Institute for Advanced Studies-IEAV/DCTA, Av. Cel Jose Alberto Albano do Amarante, 1-Putim, 12228-001 São Jose dos Campos, SP (Brazil); Araujo, J.R., E-mail: jraraujo@inmetro.gov.br [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil); Ferreira, E.H.M. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil); Strohmeier, B.R. [Thermo Fisher Scientific, 5225 Verona Road, Madison, WI 53711 (United States); Silva, L.G.A., E-mail: lgasilva@ipen.br [Institute for Nuclear and Energy Research- IPEN, Av. Prof lineu Prestes, 2242- Cidade Universitaria, 05508-000 SP (Brazil); Achete, C.A. [Instituto Nacional de Metrologia, Qualidade e Tecnologia, Av. Nossa Sra. das Graças, 50, 25250-020 Duque de Caxias, RJ (Brazil)

    2015-04-30

    Graphical abstract: - Highlights: • Methodology for the functionalization of carbon nanofibers was investigated. • Two radiation sources were used to promote grafting reactions: gamma and electron beam. • We report the optimum inhibitor concentration to achieve the functionalization. • Surface of carbon nanofibers showed an increase of oxygen content after irradiation. • The radiation-induced graphitization did not damage the overall sp{sup 2} structure. - Abstract: Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO{sub 4}·7H{sub 2}O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

  9. Superior Electrochemical Properties of Nanofibers Composed of Hollow CoFe2 O4 Nanospheres Covered with Onion-Like Graphitic Carbon.

    Science.gov (United States)

    Hong, Young Jun; Cho, Jung Sang; Kang, Yun Chan

    2015-12-07

    Nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are prepared by applying nanoscale Kirkendall diffusion to the electrospinning process. Amorphous carbon nanofibers embedded with CoFe2 @onion-like carbon nanospheres are prepared by reduction of the electrospun nanofibers. Oxidation of the CoFe2 -C nanofibers at 300 °C under a normal atmosphere produces porous nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon. CoFe2 nanocrystals are transformed into the hollow CoFe2 O4 nanospheres during oxidation through a well-known nanoscale Kirkendall diffusion process. The discharge capacities of the carbon-free CoFe2 O4 nanofibers composed of hollow nanospheres and the nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are 340 and 930 mA h g(-1) , respectively, for the 1000th cycle at a current density of 1 A g(-1) . The nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon exhibit an excellent rate performance even in the absence of conductive materials.

  10. High performance piezoelectric devices based on aligned arrays of nanofibers of poly(vinylidenefluoride-co-trifluoroethylene)

    Science.gov (United States)

    Persano, Luana; Dagdeviren, Canan; Su, Yewang; Zhang, Yihui; Girardo, Salvatore; Pisignano, Dario; Huang, Yonggang; Rogers, John A.

    2013-03-01

    Multifunctional capability, flexible design, rugged lightweight construction and self-powered operation are desired attributes for electronics that directly interface with the human body or with advanced robotic systems. For these applications, piezoelectric materials, in forms that offer the ability to bend and stretch, are attractive for pressure/force sensors and mechanical energy harvesters. Here, we introduce a large area, flexible piezoelectric material that consists of sheets of electrospun fibres of the polymer poly[(vinylidenefluoride-co-trifluoroethylene]. The flow and mechanical conditions associated with the spinning process yield free-standing, three-dimensional architectures of aligned arrangements of such fibres, in which the polymer chains adopt strongly preferential orientations. The resulting material offers exceptional piezoelectric characteristics, to enable ultra-high sensitivity for measuring pressure, even at exceptionally small values (0.1 Pa). Quantitative analysis provides detailed insights into the pressure sensing mechanisms, and establishes engineering design rules. Potential applications range from self-powered micro-mechanical elements, to self-balancing robots and sensitive impact detectors.

  11. High performance piezoelectric devices based on aligned arrays of nanofibers of poly(vinylidenefluoride-co-trifluoroethylene).

    Science.gov (United States)

    Persano, Luana; Dagdeviren, Canan; Su, Yewang; Zhang, Yihui; Girardo, Salvatore; Pisignano, Dario; Huang, Yonggang; Rogers, John A

    2013-01-01

    Multifunctional capability, flexible design, rugged lightweight construction and self-powered operation are desired attributes for electronics that directly interface with the human body or with advanced robotic systems. For these applications, piezoelectric materials, in forms that offer the ability to bend and stretch, are attractive for pressure/force sensors and mechanical energy harvesters. Here, we introduce a large area, flexible piezoelectric material that consists of sheets of electrospun fibres of the polymer poly[(vinylidenefluoride-co-trifluoroethylene]. The flow and mechanical conditions associated with the spinning process yield free-standing, three-dimensional architectures of aligned arrangements of such fibres, in which the polymer chains adopt strongly preferential orientations. The resulting material offers exceptional piezoelectric characteristics, to enable ultra-high sensitivity for measuring pressure, even at exceptionally small values (0.1 Pa). Quantitative analysis provides detailed insights into the pressure sensing mechanisms, and establishes engineering design rules. Potential applications range from self-powered micro-mechanical elements, to self-balancing robots and sensitive impact detectors.

  12. Development and Characterization of a Bioinspired Bone Matrix with Aligned Nanocrystalline Hydroxyapatite on Collagen Nanofibers

    Directory of Open Access Journals (Sweden)

    Hsi-Chin Wu

    2016-03-01

    Full Text Available Various kinds of three-dimensional (3D scaffolds have been designed to mimic the biological spontaneous bone formation characteristics by providing a suitable microenvironment for osteogenesis. In view of this, a natural bone-liked composite scaffold, which was combined with inorganic (hydroxyapatite, Hap and organic (type I collagen, Col phases, has been developed through a self-assembly process. This 3D porous scaffold consisting of a c-axis of Hap nanocrystals (nHap aligning along Col fibrils arrangement is similar to natural bone architecture. A significant increase in mechanical strength and elastic modulus of nHap/Col scaffold is achieved through biomimetic mineralization process when compared with simple mixture of collagen and hydroxyapatite method. It is suggested that the self-organization of Hap and Col produced in vivo could also be achieved in vitro. The oriented nHap/Col composite not only possesses bone-like microstructure and adequate mechanical properties but also enhances the regeneration and reorganization abilities of bone tissue. These results demonstrated that biomimetic nHap/Col can be successfully reconstructed as a bone graft substitute in bone tissue engineering.

  13. Vertically aligned N-doped coral-like carbon fiber arrays as efficient air electrodes for high-performance nonaqueous Li-O2 batteries.

    Science.gov (United States)

    Shui, Jianglan; Du, Feng; Xue, Chenming; Li, Quan; Dai, Liming

    2014-03-25

    High energy efficiency and long cycleability are two important performance measures for Li-air batteries. Using a rationally designed oxygen electrode based on a vertically aligned nitrogen-doped coral-like carbon nanofiber (VA-NCCF) array supported by stainless steel cloth, we have developed a nonaqueous Li-O2 battery with an energy efficiency as high as 90% and a narrow voltage gap of 0.3 V between discharge/charge plateaus. Excellent reversibility and cycleability were also demonstrated for the newly developed oxygen electrode. The observed outstanding performance can be attributed to its unique vertically aligned, coral-like N-doped carbon microstructure with a high catalytic activity and an optimized oxygen/electron transportation capability, coupled with the microporous stainless steel substrate. These results demonstrate that highly efficient and reversible Li-O2 batteries are feasible by using a rationally designed carbon-based oxygen electrode.

  14. Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Che Azurahanim Che; Asanithi, Piyapong; Brunner, Eric W; Jurewicz, Izabela; Bo, Chiara; Sear, Richard P; Dalton, Alan B [Department of Physics and Surrey Materials Institute, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Azad, Chihye Lewis; Ovalle-Robles, Raquel; Fang Shaoli; Lima, Marcio D; Lepro, Xavier; Collins, Steve; Baughman, Ray H, E-mail: r.sear@surrey.ac.uk [Alan G MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080-3021 (United States)

    2011-05-20

    Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.

  15. Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

    Science.gov (United States)

    Azurahanim Che Abdullah, Che; Asanithi, Piyapong; Brunner, Eric W.; Jurewicz, Izabela; Bo, Chiara; Azad, Chihye Lewis; Ovalle-Robles, Raquel; Fang, Shaoli; Lima, Marcio D.; Lepro, Xavier; Collins, Steve; Baughman, Ray H.; Sear, Richard P.; Dalton, Alan B.

    2011-05-01

    Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.

  16. Preparation of very long and open aligned carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    潘正伟; 常保和; 孙连峰; 钱露茜; 刘祖琴; 唐东升; 王刚; 解思深

    2000-01-01

    Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surface, where iron/silica nano-composite particles are evenly positioned. The nanotubes are naturally opened at the bottom ends. The growth mechanism of the very long and open-ended nanotubes is also discussed.

  17. Towards ultrathick battery electrodes: aligned carbon nanotube-enabled architecture.

    Science.gov (United States)

    Evanoff, Kara; Khan, Javed; Balandin, Alexander A; Magasinski, Alexandre; Ready, W Jud; Fuller, Thomas F; Yushin, Gleb

    2012-01-24

    Vapor deposition techniques were utilized to synthesize very thick (∼1 mm) Li-ion battery anodes consisting of vertically aligned carbon nanotubes coated with silicon and carbon. The produced anode demonstrated ultrahigh thermal (>400 W·m(-1) ·K(-1)) and high electrical (>20 S·m(-1)) conductivities, high cycle stability, and high average capacity (>3000 mAh·g(Si) (-1)). The processes utilized allow for the conformal deposition of other materials, thus making it a promising architecture for the development of Li-ion anodes and cathodes with greatly enhanced electrical and thermal conductivities.

  18. Mechanism of Carbon Nanotubes Aligning along Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    MA Shao-Jie; GUO Wan-Lin

    2008-01-01

    The mechanism of single-walled carbon nanotubes (SWCNTS)aligning in the direction of external electric field is studied by quantum mechanics calculations.The rotational torque on the carbon nanotubes is proportional to the difference between the longitudinal and transverse polarizabilities and varies with the angle of SWCNTs to the external electric field.The longitudinal polarizability increases with second power of length,while the transverse polarizability increases linearly with length.A zigzag SWCNT has larger longitudinal and transverse polarizabilities than an armchair SWCNT with the same diameter and the discrepancy becomes larger for longer tubes.

  19. Large-scale synthesis of flexible free-standing SERS substrates with high sensitivity: electrospun PVA nanofibers embedded with controlled alignment of silver nanoparticles.

    Science.gov (United States)

    He, Dian; Hu, Bo; Yao, Qiao-Feng; Wang, Kan; Yu, Shu-Hong

    2009-12-22

    A new and facile way to synthesize a free-standing and flexible surface-enhanced Raman scattering (SERS) substrate has been successfully developed, where high SERS-active Ag dimers or aligned aggregates are assembled within poly(vinyl alcohol) (PVA) nanofibers with chain-like arrays via electrospinning technique. The aggregation state of the obtained Ag nanoparticle dimers or larger, which are formed in a concentrated PVA solution, makes a significant contribution to the high sensitivity of SERS to 4-mercaptobenzoic acid (4-MBA) molecules with an enhancement factor (EF) of 10(9). The superiority of enhancement ability of this Ag/PVA nanofiber mat is also shown in the comparison to other substrates. Furthermore, the Ag/PVA nanofiber mat would keep a good reproducibility under a low concentration of 4-MBA molecule (10(-6) M) detection with the average RSD values of the major Raman peak less than 0.07. The temporal stability of the substrate has also been demonstrated. This disposable, easy handled, flexible free-standing substrate integrated the advantages including the superiority of high sensitivity, reproducibility, stability, large-scale, and low-cost production compared with other conventional SERS substrates, implying that it is a perfect choice for practical SERS detection application.

  20. Aligned carbon nanotube array stiffness from stochastic three-dimensional morphology

    Science.gov (United States)

    Stein, Itai Y.; Lewis, Diana J.; Wardle, Brian L.

    2015-11-01

    The landmark theoretical properties of low dimensional materials have driven more than a decade of research on carbon nanotubes (CNTs) and related nanostructures. While studies on isolated CNTs report behavior that aligns closely with theoretical predictions, studies on cm-scale aligned CNT arrays (>1010 CNTs) oftentimes report properties that are orders of magnitude below those predicted by theory. Using simulated arrays comprised of up to 105 CNTs with realistic stochastic morphologies, we show that the CNT waviness, quantified via the waviness ratio (w), is responsible for more than three orders of magnitude reduction in the effective CNT stiffness. Also, by including information on the volume fraction scaling of the CNT waviness, the simulation shows that the observed non-linear enhancement of the array stiffness as a function of the CNT close packing originates from the shear and torsion deformation mechanisms that are governed by the low shear modulus (~1 GPa) of the CNTs.The landmark theoretical properties of low dimensional materials have driven more than a decade of research on carbon nanotubes (CNTs) and related nanostructures. While studies on isolated CNTs report behavior that aligns closely with theoretical predictions, studies on cm-scale aligned CNT arrays (>1010 CNTs) oftentimes report properties that are orders of magnitude below those predicted by theory. Using simulated arrays comprised of up to 105 CNTs with realistic stochastic morphologies, we show that the CNT waviness, quantified via the waviness ratio (w), is responsible for more than three orders of magnitude reduction in the effective CNT stiffness. Also, by including information on the volume fraction scaling of the CNT waviness, the simulation shows that the observed non-linear enhancement of the array stiffness as a function of the CNT close packing originates from the shear and torsion deformation mechanisms that are governed by the low shear modulus (~1 GPa) of the CNTs. Electronic

  1. Thin, Flexible Supercapacitors Made from Carbon Nanofiber Electrodes Decorated at Room Temperature with Manganese Oxide Nanosheets

    Directory of Open Access Journals (Sweden)

    S. K. Nataraj

    2013-01-01

    Full Text Available We report the fabrication and electrochemical performance of a flexible thin film supercapacitor with a novel nanostructured composite electrode. The electrode was prepared by in situ coprecipitation of two-dimensional (2D MnO2 nanosheets at room temperature in the presence of carbon nanofibers (CNFs. The highest specific capacitance of 142 F/g was achieved for CNFs-MnO2 electrodes in sandwiched assembly with PVA-H4SiW12O40·nH2O polyelectrolyte separator.

  2. Plum-branch-like carbon nanofibers decorated with SnO2 nanocrystals

    Science.gov (United States)

    Yang, Zunxian; Du, Guodong; Guo, Zaiping; Yu, Xuebin; Li, Sean; Chen, Zhixin; Zhang, Peng; Liu, Huakun

    2010-06-01

    Novel plum-branch-like carbon nanofibers (CNFs) decorated with SnO2 nanocrystals have been synthesized by electrospinning and subsequent thermal treatment in an Ar/H2O atmosphere. The morphologies of the as-synthesized SnO2/CNF composites and the contents of carbon and SnO2 can be controlled by adjusting the heat treatment temperature. It is proposed that the growth of SnO2/CNF composites follows the outward diffusion of tin composites from the as-spun tin composite/polyacrylonitrile (PAN) nanofibers, pyrolysis of PAN and oxidation of tin composites, and then formation of SnO2 nanocrystals around the CNFs. This novel 1D SnO2/CNF composite may have potential application in nanobatteries, nano fuel cells, and nanosensors. A preliminary result has revealed that the SnO2/CNF composite presents favourable electrochemical performance in lithium-ion batteries.Novel plum-branch-like carbon nanofibers (CNFs) decorated with SnO2 nanocrystals have been synthesized by electrospinning and subsequent thermal treatment in an Ar/H2O atmosphere. The morphologies of the as-synthesized SnO2/CNF composites and the contents of carbon and SnO2 can be controlled by adjusting the heat treatment temperature. It is proposed that the growth of SnO2/CNF composites follows the outward diffusion of tin composites from the as-spun tin composite/polyacrylonitrile (PAN) nanofibers, pyrolysis of PAN and oxidation of tin composites, and then formation of SnO2 nanocrystals around the CNFs. This novel 1D SnO2/CNF composite may have potential application in nanobatteries, nano fuel cells, and nanosensors. A preliminary result has revealed that the SnO2/CNF composite presents favourable electrochemical performance in lithium-ion batteries. Electronic supplementary information (ESI) available: Figures S1-S6. See DOI: 10.1039/c0nr00009d

  3. Quantitative electrochemical detection of cathepsin B activity in complex tissue lysates using enhanced AC voltammetry at carbon nanofiber nanoelectrode arrays.

    Science.gov (United States)

    Swisher, Luxi Z; Prior, Allan M; Shishido, Stephanie; Nguyen, Thu A; Hua, Duy H; Li, Jun

    2014-06-15

    The proteolytic activity of a cancer-related enzyme cathepsin B is measured with alternating current voltammetry (ACV) using ferrocene (Fc) labeled tetrapeptides attached to nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). This combination enables the use of high AC frequencies (~1kHz) with enhanced electrochemical signals. The specific proteolysis of the Fc-peptide by cathepsin B produces decay in the ACV peak current versus the reaction time. The exponential component of the raw data can be extracted and defined as the "extracted proteolytic signal" which allows consistent quantitative analyses using a heterogeneous Michaelis-Menten model. A "specificity constant" kcat/KM = (3.68 ± 0.50) × 10(4)M(-1)s(-1) for purified cathepsin B was obtained. The detections of cathepsin B activity in different concentrations of whole lysate of human breast tissue, tissue lysate spiked with varied concentrations of cathepsin B, and the tissue lysate after immunoprecipitation showed that there is ~13.4 nM higher cathepsin B concentration in 29.1 µg mL(-1) of whole tissue lysate than the immunoprecipitated sample. The well-defined regular VACNF NEAs by e-beam lithography show a much faster kinetics for cathepsin B proteolysis with kcat/KM = 9.2 × 10(4)M(-1)s(-1). These results illustrate the potential of this technique as a portable multiplex electronic system for cancer diagnosis by rapid protease profiling of serum or blood samples.

  4. Construction of solid-state Z-scheme carbon-modified TiO2/WO3 nanofibers with enhanced photocatalytic hydrogen production

    Science.gov (United States)

    Hu, Junhua; Wang, Lijie; Zhang, Peng; Liang, Changhao; Shao, Guosheng

    2016-10-01

    Carbon-layer-coated TiO2/WO3 nanofibers (WTC) were fabricated by combining the electrospinning technique (for TiO2/WO3 nanofibers) and hydrothermal method (for carbon shell). The structure characterization results showed that TiO2/WO3 nanofibers (WT) were encased within an uniform carbon shell about 10 nm in thickness. By adjusting the content of WO3, the graphitization degree of carbon layer could be controlled, and the WTC nanofibers had remarkable light absorption in the visible region. Furthermore, the photoelectrochemical performance and photocatalytic activity were investigated systematically. As expected, the H2-generation rate of the as-prepared composite materials was greatly enhanced compared with pure TiO2 nanofibers (TNFs), TiO2/WO3 nanofibers (WT) and TiO2@carbon core/shell nanofibers (TC). The enhanced activities were mainly attributed to the multichannel-improved charge-carrier photosynthetic heterojunction system with the carbon layer on the surface of TiO2 as an electron collector and WO3 as a hole collector, leading to effective charge separation on these components, which were evidenced by photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and photocurrent analysis. Besides, the addition of WO3 promoted the graphitization of carbon layer, which in turn improved transport of electrons in the carbon layer and also contributed to the performance improvement.

  5. Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

    Science.gov (United States)

    Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

    2013-11-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

  6. Three-dimensional aligned nanofibers-hydrogel scaffold for controlled non-viral drug/gene delivery to direct axon regeneration in spinal cord injury treatment

    Science.gov (United States)

    Nguyen, Lan Huong; Gao, Mingyong; Lin, Junquan; Wu, Wutian; Wang, Jun; Chew, Sing Yian

    2017-01-01

    Spinal cord injuries (SCI) often lead to persistent neurological dysfunction due to failure in axon regeneration. Unfortunately, currently established treatments, such as direct drug administration, do not effectively treat SCI due to rapid drug clearance from our bodies. Here, we introduce a three-dimensional aligned nanofibers-hydrogel scaffold as a bio-functionalized platform to provide sustained non-viral delivery of proteins and nucleic acid therapeutics (small non-coding RNAs), along with synergistic contact guidance for nerve injury treatment. A hemi-incision model at cervical level 5 in the rat spinal cord was chosen to evaluate the efficacy of this scaffold design. Specifically, aligned axon regeneration was observed as early as one week post-injury. In addition, no excessive inflammatory response and scar tissue formation was triggered. Taken together, our results demonstrate the potential of our scaffold for neural tissue engineering applications. PMID:28169354

  7. Platinum on Carbon Nanofibers as Catalyst for Cinnamaldehyde Hydrogenation

    NARCIS (Netherlands)

    Plomp, A.J.

    2009-01-01

    The aim of the work described in this thesis was to investigate the role and nature of nanostructured carbon materials, oxygen surface groups and promoters on platinum-based catalysts for the selective hydrogenation of cinnamaldehyde. The selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

  8. Vertically aligned carbon nanotube field-effect transistors

    KAUST Repository

    Li, Jingqi

    2012-10-01

    Vertically aligned carbon nanotube field-effect transistors (CNTFETs) have been developed using pure semiconducting carbon nanotubes. The source and drain were vertically stacked, separated by a dielectric, and the carbon nanotubes were placed on the sidewall of the stack to bridge the source and drain. Both the effective gate dielectric and gate electrode were normal to the substrate surface. The channel length is determined by the dielectric thickness between source and drain electrodes, making it easier to fabricate sub-micrometer transistors without using time-consuming electron beam lithography. The transistor area is much smaller than the planar CNTFET due to the vertical arrangement of source and drain and the reduced channel area. © 2012 Elsevier Ltd. All rights reserved.

  9. Terahertz Science and Technology of Macroscopically Aligned Carbon Nanotube Films

    Science.gov (United States)

    Kono, Junichiro

    One of the outstanding challenges in nanotechnology is how to assemble individual nano-objects into macroscopic architectures while preserving their extraordinary properties. For example, the one-dimensional character of electrons in individual carbon nanotubes leads to extremely anisotropic transport, optical, and magnetic phenomena, but their macroscopic manifestations have been limited. Here, we describe methods for preparing macroscopic films, sheets, and fibers of highly aligned carbon nanotubes and their applications to basic and applied terahertz studies. Sufficiently thick films act as ideal terahertz polarizers, and appropriately doped films operate as polarization-sensitive, flexible, powerless, and ultra-broadband detectors. Together with recently developed chirality enrichment methods, these developments will ultimately allow us to study dynamic conductivities of interacting one-dimensional electrons in macroscopic single crystals of single-chirality single-wall carbon nanotubes.

  10. Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    Juan Carlos Calderón

    2016-10-01

    Full Text Available In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2. From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding—as a rate determining step—the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies.

  11. Fabrication of a Mechanically Robust Carbon Nanofiber Foam

    Science.gov (United States)

    2015-06-01

    seal. 8 Both mold inlet and outlet connections were created using Swagelok brand 1/4th inch fittings. The fittings were arranged to enable the...piece of stainless steel shim (Trinity Brand Industries, Inc., Part No. 6316–4) that ran the length of the main chamber inlets and is shown in Figure...2006. [10] W. Hung et al., “Rapid prototyping of three-dimensional microstructures from multiwalled carbon nanotubes,” Appl . Phys. Lett., vol. 91, p

  12. Nanocomposite electrodes made of carbon nanofibers and black wax. Anodic stripping voltammetry of zinc and lead.

    Science.gov (United States)

    van Dijk, N; Fletcher, S; Madden, C E; Marken, F

    2001-11-01

    Nanocomposite electrodes offer exciting new possibilities in electroanalytical chemistry. In this preliminary study, nanocomposite electrodes made of carbon nanofibers and black wax were characterized and investigated as novel substrates for metal deposition and stripping processes. Carbon nanofibers were grown from ethylene-hydrogen gas mixtures over Fe-Ni-Cu (85:10:5) nanoparticle catalysts at 600 degrees C and then embedded in Apiezon black wax under vacuum at 140 degrees C. The resulting nanocomposite electrodes showed (i) good conductivity, (ii) a wide potential window in aqueous solutions, (iii) low background currents, (iv) near steady state voltammetric responses with substantial Faradaic currents and (v) sharply peaked fast scan metal stripping responses. Zinc is a notoriously difficult metal to determine in aqueous solutions, because its deposition and stripping are accompanied by hydrogen evolution at extreme negative potentials. It therefore provided a challenging test for our new nanocomposite electrode. Although numerous complications associated with the hydrogen evolution process could not be eliminated, remarkably clear voltammograms could be obtained even at scan rates of 40 V s(-1).

  13. Effect of Sulfur Concentration on the Morphology of Carbon Nanofibers Produced from a Botanical Hydrocarbon

    Directory of Open Access Journals (Sweden)

    Ghosh Kaushik

    2008-01-01

    Full Text Available AbstractCarbon nanofibers (CNF with diameters of 20–130 nm with different morphologies were obtained from a botanical hydrocarbon: Turpentine oil, using ferrocene as catalyst source and sulfur as a promoter by simple spray pyrolysis method at 1,000 °C. The influence of sulfur concentration on the morphology of the carbon nanofibers was investigated. SEM, TEM, Raman, TGA/DTA, and BET surface area were employed to characterize the as-prepared samples. TEM analysis confirms that as-prepared CNFs have a very sharp tip, bamboo shape, open end, hemispherical cap, pipe like morphology, and metal particle trapped inside the wide hollow core. It is observed that sulfur plays an important role to promote or inhibit the CNF growth. Addition of sulfur to the solution of ferrocene and turpentine oil mixture was found to be very effective in promoting the growth of CNF. Without addition of sulfur, carbonaceous product was very less and mainly soot was formed. At high concentration of sulfur inhibit the growth of CNFs. Hence the yield of CNFs was optimized for a given sulfur concentration.

  14. LiFePO4 - 3D carbon nanofiber composites as cathode materials for Li-ions batteries

    Science.gov (United States)

    Dimesso, L.; Spanheimer, C.; Jaegermann, W.; Zhang, Y.; Yarin, A. L.

    2012-03-01

    The characterization of carbon nanofiber 3D nonwovens, prepared by electrospinning process, coated with olivine structured lithium iron phosphate is reported. The LiFePO4 as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on carbon nanofiber 3D nonwovens by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2-4 h. After drying-out, the composites were annealed at 600 °C for 5 h under nitrogen. The surface investigation of the prepared composites showed a uniform coating of the carbon nonwoven nanofibers as well as the formation of cauliflower-like crystalline structures which are uniformly distributed all over the surface area of the carbon nanofibers. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 156 mAhg- 1 at a discharging rate of C/25 and 152 mAhg- 1 at a discharging rate of C/10 at room temperature.

  15. Stability and activity of carbon nanofiber-supported catalysts in the aqueous phase reforming of ethylene glycol

    NARCIS (Netherlands)

    van Haasterecht, T.; Ludding, C.C.I.; de Jong, K.P.; Bitter, J.H.

    2013-01-01

    Nickel, cobalt, copper and platinum nanoparticles supported on carbon nano-fibers were evaluated with respect to their stability, catalytic activity and selectivity in the aqueous phase reforming of ethylene glycol (230 ◦C, autogenous pressure, batch reactor). The initial surface-specific activities

  16. Stability and activity of carbon nanofiber-supported catalysts in the aqueous phase reforming of ethylene glycol

    NARCIS (Netherlands)

    Haasterecht, van T.; Ludding, C.C.I.; Jong, de K.P.; Bitter, J.H.

    2013-01-01

    Nickel, cobalt, copper and platinum nanoparticles supported on carbon nano-fibers were evaluated with respect to their stability, catalytic activity and selectivity in the aqueous phase reforming of ethylene glycol (230 ¿, autogenous pressure, batch reactor). The initial surface-specific activities

  17. Growing a carbon nano-fiber layer on a monolith support; effect of nickel loading and growth conditions

    NARCIS (Netherlands)

    Jarrah, Nabeel A.; Ommen, van Jan G.; Lefferts, Leon

    2004-01-01

    This work describes how a new, extremely porous, hairy layer of carbon nano-fibers (CNFs) can be prepared on the surface of porous inorganic bodies, e.g. wash-coated monoliths. CNFs were prepared catalytically by methane and ethene decomposition over a Ni catalyst. The influence of the Ni particle s

  18. Effect of Sodium Carbonate Concentrations on the Formation and Mechanism of Regenerated Silk Fibroin Nanofibers by Electrospinning

    Directory of Open Access Journals (Sweden)

    Hao Dou

    2014-01-01

    Full Text Available Degumming is the first process for the preparation of all silk-based products. In this paper, effect of sodium carbonate concentrations for silk degumming on the formation of electrospun silk fibroin nanofibers was investigated and the reason for the silk electrospinning process was explained for the first time by differences from the microstructure of regenerated silk fibroin. With increasing the sodium carbonate concentration, microstructure both in the aqueous solutions and in the electrospinning solutions transformed from nanofibrils to nanoparticles, leading to obvious changes on rheological property; electrospinning solutions with nanofibrils behaved like the native silk dope and owned remarkably higher viscosity than the solutions with nanoparticles showing very low viscosity. More interestingly, nanofibrils favored the formation of silk nanofibers with ease, and even nanofibers could be electrospun at concentration 2%. However, nanoparticles were completely unable to generate nanofibers at high spinning concentration 8%. Importance of sodium carbonate concentrations is heavily emphasized for impacting the microstructure types and further influencing the electrospinning performance of regenerated silk. Hence, sodium carbonate concentrations provide a controllable choice for the preparation of silk-based electrospun biomaterials with desired properties.

  19. Vertically Aligned Carbon Nanotube Electrodes for Lithium-Ion Batteries

    Science.gov (United States)

    2011-01-01

    37] Z. Yang, H. Wu, Mater. Chem. Phys. 71 (2001) 7. [38] D. Linden , T.B. Reddy, Handbook of Batteries , 3rd ed., McGraw-Hill Co., Inc., New York, 2005. ...Lithium-ion Energy storage Battery a b s t r a c t As portable electronics becomemore advanced and alternative energy demands becomemore prevalent, the...aligned carbon nanotube electrodes for lithium-ion batteries 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d. PROJECT

  20. Touch- and Brush-Spinning of Nanofibers.

    Science.gov (United States)

    Tokarev, Alexander; Asheghali, Darya; Griffiths, Ian M; Trotsenko, Oleksandr; Gruzd, Alexey; Lin, Xin; Stone, Howard A; Minko, Sergiy

    2015-11-01

    Robust, simple, and scalable touch- and brush-spinning methods for the drawing of nanofibers, core-shell nanofibers, and their aligned 2D and 3D meshes using polymer solutions and melts are discussed.

  1. Carbon nanotube-templated polyaniline nanofibers: synthesis, flash welding and ultrafiltration membranes

    Science.gov (United States)

    Liao, Yaozu; Yu, Deng-Guang; Wang, Xia; Chain, Wei; Li, Xin-Gui; Hoek, Eric M. V.; Kaner, Richard B.

    2013-04-01

    Electro-active switchable ultrafiltration membranes are of great interest due to the possibility of external control over permeability, selectivity, anti-fouling and cleaning. Here, we report on hybrid single-walled carbon nanotube (SWCNT)-polyaniline (PANi) nanofibers synthesized by in situ polymerization of aniline in the presence of oxidized SWCNTs. The composite nanofibers exhibit unique morphology of core-shell (SWCNT-PANi) structures with average total diameters of 60 nm with 10 to 30 nm thick PANi coatings. The composite nanofibers are easily dispersed in polar aprotic solvents and cast into asymmetric membranes via a nonsolvent induced phase separation. The hybrid SWCNT-PANi membranes are electrically conductive at neutral pH and exhibit ultrafiltration-like permeability and selectivity when filtering aqueous suspensions of 6 nm diameter bovine serum albumin and 48 nm diameter silica particles. A novel flash welding technique is utilized to tune the morphology, porosity, conductivity, permeability and nanoparticle rejection of the SWCNT-PANi composite ultrafiltration membranes. Upon flash welding, both conductivity and pure water permeability of the membranes improves by nearly a factor of 10, while maintaining silica nanoparticle rejection levels above 90%. Flash welding of SWCNT-PANi composite membranes holds promise for formation of electrochemically tunable membranes.Electro-active switchable ultrafiltration membranes are of great interest due to the possibility of external control over permeability, selectivity, anti-fouling and cleaning. Here, we report on hybrid single-walled carbon nanotube (SWCNT)-polyaniline (PANi) nanofibers synthesized by in situ polymerization of aniline in the presence of oxidized SWCNTs. The composite nanofibers exhibit unique morphology of core-shell (SWCNT-PANi) structures with average total diameters of 60 nm with 10 to 30 nm thick PANi coatings. The composite nanofibers are easily dispersed in polar aprotic solvents and

  2. Tin Oxide-Carbon-Coated Sepiolite Nanofibers with Enhanced Lithium-Ion Storage Property.

    Science.gov (United States)

    Hou, Kai; Wen, Xin; Yan, Peng; Tang, Aidong; Yang, Huaming

    2017-12-01

    Natural sepiolite (Sep) nanofibers were coated with carbon and nanoscale SnO2 to prepare an emerging nanocomposite (SnO2-C@Sep), which exhibited enhanced electrochemical performance. Sepiolite could act as a steady skeleton, carbon coating principally led sepiolite from an isolated to an electric state, and decoration of nanoscale SnO2 was beneficial to the functionization of sepiolite. Cycling performances indicated that SnO2-C@Sep showed higher discharge capacities than commercial SnO2 after 50 cycles. The nanocomposite SnO2-C@Sep possessed enhanced lithium storage properties with stable capacity retention and low cost, which could open up a new strategy to synthesize a variety of functional hybrid materials based on the cheap and abundant clay and commercialization of lithium-metal oxide batteries.

  3. A New Strategy to Pretreat Carbon Nanofiber and Its Application in Determination of Dopamine

    Directory of Open Access Journals (Sweden)

    Dong Liu

    2010-01-01

    Full Text Available A novel sonochemical process, using hydrogen peroxide in a laboratory ultrasonic bath, was employed to pretreat the carbon nanofiber (CNF for creating oxygen-rich groups on the surface of CNF. After the sonochemical process, the CNF showed good hydrophilicity and high electrochemical activity. Compared to normal pretreatment process, this sonochemical process is timesaving and effective for dispersion and functionalization of CNF. The resulting CNF showed high catalytic activity toward the oxidation of DA. A carbon paste electrode modified by CNF (CPE-CNF was used to determine the dopamine (DA in the presence of ascorbic acid (AA. The detection limit is 0.05 μM, with the linear range from 0.05 μM to 6.4 μM.

  4. Free-Standing Porous Carbon Nanofiber Networks from Electrospinning Polyimide for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2016-01-01

    Full Text Available Free-standing porous carbon nanofiber networks (CFNs were synthesized by electrospinning method and carbonization procedure. We study the implementation of porous CFNs as supercapacitor electrodes and electrochemical measurements demonstrated that porous CFNs exhibit a specific capacitance (205 F/g at the scan rate of 5 mV/s with high flexibility and good rate capability performance (more than 70% of its initial capacitance from 5 mV/s to 200 mV/s. Furthermore, porous CFNs exhibited an excellent cycling stability (just 12% capacitance loss after 10,000 cycles. These results suggest that porous CFNs are very promising candidates as flexible supercapacitor electrodes.

  5. Mass Production of Carbon Nanofibers Using Microwave Technology.

    Science.gov (United States)

    Mubarak, N M; Abdullah, E C; Sahu, J N; Jayakumar, N S; Ganesan, P

    2015-12-01

    Carbon nanotubes (CNFs) were produced by gas phase single stage microwave assisted chemical vapour deposition (MA-CVD) using ferrocene as a catalyst and acetylene (C2H2) and hydrogen (H2) as precursor gases. The effect of the process parameters such as microwave power, radiation time, and gas ratio of C2H2/H2 was investigated. The CNFs were characterized using scanning and transmission electron microscopy (TEM), and by thermogravimetric analysis (TGA). Results reveal that the optimized conditions for CNF production were 1000 W reaction power, 35 min radiation time, and 0.8 gas ratio of C2H2/H2. TEM analyses revealed that the uniformly dispersed CNFs diameters ranging from 115-131 nm. The TGA analysis showed that the purity of CNF produced was 93%.

  6. Supercritical fluid attachment of palladium nanoparticles on aligned carbon nanotubes.

    Science.gov (United States)

    Ye, Xiang-Rong; Lin, Yuehe; Wai, Chien M; Talbot, Jan B; Jin, Sungho

    2005-06-01

    Nanocomposite materials consisting of Pd nanoparticles deposited on aligned multi-walled carbon nanotubes have been fabricated through hydrogen reduction of palladium-beta-diketone precursor in supercritical carbon dioxide. The supercritical fluid processing allowed deposition of high-density Pd nanoparticles (approximately 5-10 nm) on both as-grown (unfunctionalized) and functionalized (using HNO3 oxidation) nanotubes. However, the wet processing for functionalization results in pre-agglomerated, bundle-shaped nanotubes, thus significantly reducing the effective surface area for Pd particle deposition, although the bundling provides more secure, lock-in-place positioning of nanotubes and Pd catalyst particles. The nanotube bundling is substantially mitigated by Pd nanoparticle deposition on the unfunctionalized and geometrically separated nanotubes, which provides much higher catalyst surface area. Such nanocomposite materials utilizing geometrically secured and aligned nanotubes can be useful for providing much enhanced catalytic activities to chemical and electrochemical reactions (e.g., fuel cell reactions), and eliminate the need for tedious catalyst recovery process after the reaction is completed.

  7. Fabrication of electrospun nanofibers bundles

    Science.gov (United States)

    Ye, Junjun; Sun, Daoheng

    2007-12-01

    Aligned nanofibers, filament bundle composed of large number of nanofibers have potential applications such as bio-material, composite material etc. A series of electrospinning experiments have been conducted to investigate the electrospinning process,in which some parameters such as polymer solution concentration, bias voltage, distance between spinneret and collector, solution flow rate etc have been setup to do the experiment of nanofibers bundles construction. This work firstly reports electrospun nanofiber bundle through non-uniform electrical field, and nanofibers distributed in different density on electrodes from that between them. Thinner nanofibers bundle with a few numbers of nanofiber is collected for 3 seconds; therefore it's also possible that the addressable single nanofiber could be collected to bridge two electrodes.

  8. How does surface modification aid in the dispersion of carbon nanofibers?

    Science.gov (United States)

    Zhao, Jian; Schaefer, Dale W; Shi, Donglu; Lian, Jie; Brown, Janis; Beaucage, Gregory; Wang, Lumin; Ewing, Rodney C

    2005-12-15

    Small-angle light scattering is used to assess the dispersion behavior of vapor-grown carbon nanofibers suspended in water. These data provide the first insights into the mechanism by which surface treatment promotes dispersion. Both acid-treated and untreated nanofibers exhibit hierarchical morphology consisting of small-scale aggregates (small bundles) that agglomerate to form fractal clusters that eventually precipitate. Although the morphology of the aggregates and agglomerates is nearly independent of surface treatment, their time evolution is quite different. The time evolution of the small-scale bundles is studied by extracting the size distribution from the angle-dependence of the scattered intensity, using the maximum entropy method in conjunction with a simplified tube form factor. The bundles consist of multiple tubes possibly aggregated side-by-side. Acid oxidation has little effect on this bundle morphology. Rather acid treatment inhibits agglomeration of the bundles. The time evolution of agglomeration is followed by fitting the scattering data to a generalized fractal model. Agglomerates appear immediately after cessation of sonication for untreated fibers but only after hours for treated fibers. Eventually, however, both systems precipitate.

  9. Graphitic carbon nanofiber (GCNF)/polymer materials. I. GCNF/epoxy monoliths using hexanediamine linker molecules.

    Science.gov (United States)

    Zhong, Wei-Hong; Li, Jiang; Xu, Luoyu R; Michel, Jason A; Sullivan, Lisa M; Lukehart, Charles M

    2004-09-01

    Processing methods have been optimized for the formation of graphitic carbon nanofiber (GCNF)/epoxy nanocomposites containing GCNFs highly dispersed throughout a thermoset epoxy matrix. GCNFs having a herringbone atomic structure are surface-derivatized with bifunctional hexanediamine linker molecules (GCNF-HDA) capable of covalent binding to an epoxy matrix during thermal curing and are cut to smaller dimension using high-power ultrasonication. GCNF-HDA nanofibers are dispersed in epoxy resin at 0.3 wt.% loading using variable levels of ultrasonication processing prior to thermal curing. Effects of sonication power on the quality of the GCNF-HDA/epoxy material obtained after curing have been determined from flexural property measurements, thermomechanical analysis and SEM/TEM imaging. GCNF-HDA/epoxy material of the highest quality is obtained using low-power sonication, although high-power sonication for short periods gives improved flexural properties without lowering the glass transition temperature. Good dispersion and polymer wetting of the GCNF component is evident on the nanoscale.

  10. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    Directory of Open Access Journals (Sweden)

    Takeshi Hikata

    2013-04-01

    Full Text Available We produced novel carbon nanofibers (CNFs by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  11. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    Science.gov (United States)

    Hikata, Takeshi; Okubo, Soichiro; Higashi, Yugo; Matsuba, Teruaki; Utsunomiya, Risa; Tsurekawa, Sadahiro; Murakami, Katsuhisa; Fujita, Jun-ichi

    2013-04-01

    We produced novel carbon nanofibers (CNFs) by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  12. Graphitic Carbon-Coated FeSe2 Hollow Nanosphere-Decorated Reduced Graphene Oxide Hybrid Nanofibers as an Efficient Anode Material for Sodium Ion Batteries

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jung-Kul; Kang, Yun Chan

    2016-04-01

    A novel one-dimensional nanohybrid comprised of conductive graphitic carbon (GC)-coated hollow FeSe2 nanospheres decorating reduced graphene oxide (rGO) nanofiber (hollow nanosphere FeSe2@GC-rGO) was designed as an efficient anode material for sodium ion batteries and synthesized by introducing the nanoscale Kirkendall effect into the electrospinning method. The electrospun nanofibers transformed into hollow nanosphere FeSe2@GC-rGO hybrid nanofibers through a Fe@GC-rGO intermediate. The discharge capacities of the bare FeSe2 nanofibers, nanorod FeSe2-rGO-amorphous carbon (AC) hybrid nanofibers, and hollow nanosphere FeSe2@GC-rGO hyrbid nanofibers at a current density of 1 A g-1 for the 150th cycle were 63, 302, and 412 mA h g-1, respectively, and their corresponding capacity retentions measured from the 2nd cycle were 11, 73, and 82%, respectively. The hollow nanosphere FeSe2@GC-rGO hybrid nanofibers delivered a high discharge capacity of 352 mA h g-1 even at an extremely high current density of 10 A g-1. The enhanced electrochemical properties of the hollow nanosphere FeSe2@GC-rGO composite nanofibers arose from the synergetic effects of the FeSe2 hollow morphology and highly conductive rGO matrix.

  13. Carbon nanofibers suppress fungal inhibition of seed germination of maize (Zea mays) and barley (Hordeum vulgare L.) crop

    Science.gov (United States)

    Joshi, Anjali; Sharma, Arti; Nayyar, Harsh; Verma, Gaurav; Dharamvir, Keya

    2015-08-01

    Carbon nanofibers (CNFs) are one of allotropes of carbon, consists of graphene layers arrangement in the form of stacked cones or like a cup diameter in nanometer and several millimeters in length. Their extraordinary mechanical, chemical and electronic properties are due to their small size. CNFs have been successfully applied in field of medicine in variety of diagnostic methods. They proven to be an excellent system for drug delivery, tissue regeneration, biosensor etc. This research focuses the applications of CNFs in all fields of Agriculture. In the we treated some fungal disease seed of maize and barley using functionalised CNFs. We find that the tested seeds grow just as well as the healthy seeds whereas the untreated fungal disease seeds, by themselves show very poor germination and seedling growth. This simple experiment shows the extraordinary ability of Carbon nanofibers in carrying effectively inside the germinated seeds.

  14. Carbon nanofibers suppress fungal inhibition of seed germination of maize (Zea mays) and barley (Hordeum vulgare L.) crop

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Anjali, E-mail: joshianjali1982@gmail.com; Sharma, Arti [Centre For Nanoscience and Nanotechnology, Panjab University, Chandigarh (India); Nayyar, Harsh [Department of Botany, Panjab University, Chandigarh (India); Verma, Gaurav [Dr. SS Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh (India); Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh (India)

    2015-08-28

    Carbon nanofibers (CNFs) are one of allotropes of carbon, consists of graphene layers arrangement in the form of stacked cones or like a cup diameter in nanometer and several millimeters in length. Their extraordinary mechanical, chemical and electronic properties are due to their small size. CNFs have been successfully applied in field of medicine in variety of diagnostic methods. They proven to be an excellent system for drug delivery, tissue regeneration, biosensor etc. This research focuses the applications of CNFs in all fields of Agriculture. In the we treated some fungal disease seed of maize and barley using functionalised CNFs. We find that the tested seeds grow just as well as the healthy seeds whereas the untreated fungal disease seeds, by themselves show very poor germination and seedling growth. This simple experiment shows the extraordinary ability of Carbon nanofibers in carrying effectively inside the germinated seeds.

  15. Electrochemical performance of fulvic acid-based electrospun hard carbon nanofibers as promising anodes for sodium-ion batteries

    Science.gov (United States)

    Zhao, Pin-Yi; Zhang, Jie; Li, Qi; Wang, Cheng-Yang

    2016-12-01

    The electrochemical performance of fulvic acid-based electrospun hard carbon nanofibers (PF-CNFs) as anodes for sodium-ion batteries is reported. PF-CNFs were prepared, stabilization in air at 280 °C and then carbonized in N2 at 800, 1000, 1300 or 1500 °C. The PF-CNFs prepared at 1300 °C had abundant oxygen functional groups, large interlayer spaces and stable morphologies and when used as anodes in sodium-ion batteries, a reversible sodium intercalation capacity of 248 mAh g-1 was obtained with capacity retention ratio of 91% after 100 cycles at a current density of 100 mA g-1. This large capacity combined with the superior cycling performance indicates that fulvic acid-based carbon nanofibers are promising electrode materials for use in rechargeable sodium-ion batteries.

  16. CO{sub x}-free hydrogen and carbon nanofibers production by methane decomposition over nickel-alumina catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Nima; Rezaei, Mehran; Meshkani, Fereshteh [Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2016-02-15

    Nickel catalysts supported on mesoporous nanocrystalline gamma alumina with various nickel loadings were prepared and employed for thermocatalytic decomposition of methane into CO{sub x}-free hydrogen and carbon nanofibers. The prepared catalysts with different nickel contents exhibited mesoporous structure with high surface area in the range of 121.3 to 66.2m{sup 2}g{sup -1}. Increasing in nickel content decreased the pore volume and increased the crystallite size. The catalytic results revealed that the nickel content and operating temperature both play important roles on the catalytic performance of the prepared catalysts. The results showed that increasing in reaction temperature increased the initial conversion of catalysts and significantly decreased the catalyst lifetime. Scanning electron microscopy (SEM) analysis of the spent catalysts evaluated at different temperatures revealed the formation of intertwined carbon filaments. The results showed that increasing in reaction temperature decreased the diameters of nanofibers and increased the formation of encapsulating carbon.

  17. Aligned Carbon Nanotube Reinforcement of Aerospace Carbon Fiber Composites: Substructural Strength Evaluation for Aerostructure Applications

    OpenAIRE

    Guzman de Villoria, Roberto; Ydrefors, L.; Hallander, P.; Ishiguro, Kyoko; Nordin, P.; Wardle, Brian L.

    2012-01-01

    Vertically aligned carbon nanotubes (VACNTs) are placed between all plies in an aerospace carbon fiber reinforced plastic laminate (unidirectional plies, [(0/90/±45)2]s) to reinforce the interlaminar region in the z-direction. Significant improvement in Mode I and II interlaminar toughness have been observed previously. In this work, several substructural in-plane strength tests relevant to aerostructures were undertaken: bolt/tension-bearing, open hole compression, and L-shape laminate be...

  18. Carbon Nanofibers Modified Graphite Felt for High Performance Anode in High Substrate Concentration Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Youliang Shen

    2014-01-01

    Full Text Available Carbon nanofibers modified graphite fibers (CNFs/GF composite electrode was prepared for anode in high substrate concentration microbial fuel cells. Electrochemical tests showed that the CNFs/GF anode generated a peak current density of 2.42 mA cm−2 at a low acetate concentration of 20 mM, which was 54% higher than that from bare GF. Increase of the acetate concentration to 80 mM, in which the peak current density of the CNFs/GF anode greatly increased and was up to 3.57 mA cm−2, was seven times as that of GF anode. Morphology characterization revealed that the biofilms in the CNFs/GF anode were much denser than those in the bare GF. This result revealed that the nanostructure in the anode not only enhanced current generation but also could tolerate high substrate concentration.

  19. Compaction of LiBH4-LiAlH4 nanoconfined in activated carbon nanofibers

    DEFF Research Database (Denmark)

    Plerdsranoy, Praphatsorn; Javadian, Payam; Jensen, Nicholai Daugaard;

    2016-01-01

    To enhance volumetric hydrogen capacity for on-board fuel cells, compaction of LiAlH4-LiBH4 nanoconfined in activated carbon nanofibers (ACNF) is for the first time proposed. Loose powders of milled and nanoconfined LiAlH4-LiBH4 samples are compacted under 976 MPa to obtain the pellet samples...... content liberated from milled LiAlH4-LiBH4 pellet is 65% of theoretical capacity in the temperature range of 80–475 °C, while that of nanoconfined LiAlH4-LiBH4 pellet is up to 80% at lower temperature of 100–400 °C. Besides, nanoconfined LiAlH4-LiBH4 pellet shows significant reduction of activation energy...

  20. Fracture Toughness of Vapor Grown Carbon Nanofiber-Reinforced Polyethylene Composites

    Directory of Open Access Journals (Sweden)

    A. R. Adhikari

    2009-01-01

    Full Text Available The impact fracture behavior of a vapor grown carbon nanofiber (VGCNF reinforced high-density polyethylene (PE composite was evaluated. The samples consisting of pure PE and composites with 10 wt% and 20 wt% of VGCNFs were prepared by a combination of hot-pressing and extrusion methods. Extrusion was used to produce samples with substantially different shear histories. The fracture behavior of these samples was analyzed using the essential work of fracture (EWF approach. The results showed an increase of 292% in the essential work of fracture for the loading of 10 wt%. Further increasing fiber loading to 20 wt% caused the essential work of fracture to increase only 193% with respect to the unmodified material. Evaluation of the fracture surface morphology indicated that the fibril frequency and microvoid size within the various fiber loadings depended strongly on processing conditions.

  1. Influence of Carbon Nanofiber Addition on Mechanical Properties and Crystallization Behavior of Polypropylene

    Institute of Scientific and Technical Information of China (English)

    Xin TONG; Yong CHEN; Huiming CHENG

    2005-01-01

    Carbon nanofiber (CNF)-reinforced polypropylene (CNF/PP) composites with different CNF contents were prepared by melt mixing, and the mechanical properties and crystallization behavior of the CNF/PP composites obtained were investigated. It was found that the tensile modulus of the composites was increased with the addition of CNFs, but their elongation at break and fracture strain energy were decreased, while the tensile strength of the composites was firstly increased and then decreased due to the agglomeration of CNFs at higher loading. Nonisothermal crystallization analysis showed that the CNFs played a role as nucleating agent in PP matrix, which led to increment in the crystallization rate and the degree of crystallinity of PP. Moreover, X-ray diffraction studies showed that the CNFs incorporated in the PP matrix favored the growth of (040)-oriented PP crystals. With the increase in the CNF content, the nucleating and orientation roles of the CNFs were obviously enhanced.

  2. Flexible Sensing Arrays Fabricated with Carbon Nanofiber Composite Thin Films for Posture Monitoring

    Science.gov (United States)

    Chang, Fuh-Yu; Wang, Ruoh-Huey; Lin, Yu-Hsien; Chen, Tse-Min; Lee, Yueh-Feng; Huang, Shu-Jiuan; Liu, Chia-Ming

    2011-06-01

    Faulty posture increases joint stress and causes postural pain syndrome. In this paper, we present a portable strain sensing system with flexible sensor arrays to warn patients to correct inappropriate posture. A 3×3 flexible strain sensing array system was fabricated using patterned surface treatment and the tilted-drop process with carbon nanofiber composite solutions on polyimide substrates. Atmospheric plasma was used to enhance or reduce the surface energy in specific areas for patterned surface treatment. A scanning circuit was also developed to capture the signal from the flexible sensing array. The developed system has been used to measure the bent angle of the human neck from 15 to 60°. The results indicate that human posture can be successfully captured by analyzing the measured strains from a flexible strain sensing array.

  3. Fabrication and Properties of Ethylene Vinyl Acetate-Carbon Nanofiber Nanocomposites

    Directory of Open Access Journals (Sweden)

    George JinuJacob

    2008-01-01

    Full Text Available Abstract Carbon nanofiber (CNF is one of the stiffest materials produced commercially, having excellent mechanical, electrical, and thermal properties. The reinforcement of rubbery matrices by CNFs was studied in the case of ethylene vinyl acetate (EVA. The tensile strength was greatly (61% increased, even for very low fiber content (i.e., 1.0 wt.%. The surface modification of the fiber by high energy electron beam and gamma irradiation led to better dispersion in the rubber matrix. This in turn gave rise to further improvements in mechanical and dynamic mechanical properties of EVA. The thermal conductivity also exhibited improvements from that of the neat elastomer, although thermal stability of the nanocomposites was not significantly altered by the functionalization of CNFs. Various results were well supported by the morphological analysis of the nanocomposites.

  4. Silica decorated on porous activated carbon nanofiber composites for high-performance supercapacitors

    Science.gov (United States)

    Kim, So Yeun; Kim, Bo-Hye

    2016-10-01

    A hybrid of silica decorated on porous activated carbon nanofibers (ACNFs) is fabricated in the form of a web via electrospinning and an activation process as an electrode material for electrochemical capacitors in an organic electrolyte. The introduction of PhSiH3 (PS) into the polyacrylonitrile (PAN) solution induces a porous ACNF structure containing silica nanoparticles (NPs) via the spontaneous sol-gel process of PS by steam in the subsequent physical activation process. These inorganic-organic hybrid composites of porous ACNF containing silica NPs show superior specific capacitance and energy density in electrochemical tests, along with good rate capability and excellent cycle life in an organic electrolyte, which is attributed to the combination of ACNF's high surface area and silica's hydrophilicity. The electrochemical performance decreases with increasing PS concentration, and this trend is consistent with the specific surface area results, which reveal the rapid formation of a double layer.

  5. Functionalization of carbon nanofibers with elastomeric block copolymer using carbodiimide chemistry

    Science.gov (United States)

    Mapkar, Javed A.; Iyer, Ganesh; Coleman, Maria R.

    2009-02-01

    Surface functionalization of carbon nanofibers (CNFs) with aminopropyl terminated polydimethylsiloxane [(PDMS-NH 2)] and other organic diamines was achieved using carbodiimide chemistry. The carbodiimide chemistry provides faster reaction rate so that the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. CNF functionalized with PDMS-NH 2 fibers were further functionalized with oligomer of polyimide (6FDA-BisP) using imidization reaction. The formation of block copolymer on the surface of CNF is proposed as an effective method to engineer the interphase between the fiber and the polymer, which is essential to modulate and enhance the properties of the nanocomposite. The efficiency of the carbodiimide chemistry to functionalize amine terminated groups on CNF and the functionalization of block copolymer was characterized using thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy.

  6. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites.

    Science.gov (United States)

    Liu, Tian; Wood, Weston; Zhong, Wei-Hong

    2011-12-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  7. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites

    Directory of Open Access Journals (Sweden)

    Liu Tian

    2011-01-01

    Full Text Available Abstract We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated-reinforced high-density polyethylene (HDPE composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  8. On the linear dependence of a carbon nanofiber thermal conductivity on wall thickness

    Directory of Open Access Journals (Sweden)

    Alexandros Askounis

    2016-11-01

    Full Text Available Thermal transport in carbon nanofibers (CNFs was thoroughly investigated. In particular, individual CNFs were suspended on T-type heat nanosensors and their thermal conductivity was measured over a range of temperatures. Unexpectedly, thermal conductivity was found to be dependent on CNF wall thickness and ranging between ca. 28 and 43 W/(m⋅K. Further investigation of the CNF walls with high resolution electron microscopy allowed us to propose a tentative description of how wall structure affects phonon heat transport inside CNFs. The lower thermal conductivities, compared to other CNTs, was attributed to unique CNF wall structure. Additionally, wall thickness is related to the conducting lattice length of each constituent graphene cone and comparable to the Umklapp length. Hence, as the wall thickness and thus lattice length increases there is a higher probability for phonon scattering to the next layer.

  9. Alignment control of carbon nanotube forest from random to nearly perfectly aligned by utilizing the crowding effect.

    Science.gov (United States)

    Xu, Ming; Futaba, Don N; Yumura, Motoo; Hata, Kenji

    2012-07-24

    Alignment represents an important structural parameter of carbon nanotubes (CNTs) owing to their exceptionally high aspect ratio, one-dimensional property. In this paper, we demonstrate a general approach to control the alignment of few-walled CNT forests from nearly random to nearly ideally aligned by tailoring the density of active catalysts at the catalyst formation stage, which can be experimentally achieved by controlling the CNT forest mass density. Experimentally, we found that the catalyst density and the degree of alignment were inseparably linked because of a crowding effect from neighboring CNTs, that is, the increasing confinement of CNTs with increased density. Therefore, the CNT density governed the degree of alignment, which increased monotonically with the density. This relationship, in turn, allowed the precise control of the alignment through control of the mass density. To understand this behavior further, we developed a simple, first-order model based on the flexural modulus of the CNTs that could quantitatively describe the relationship between the degree of alignment (HOF) and carbon nanotube spacing (crowding effect) of any type of CNTs.

  10. CO tolerant PtRu-MoO{sub x} nanoparticles supported on carbon nanofibers for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsiouvaras, N.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Martinez-Huerta, M.V. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Facultad de Quimicas, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071, La Laguna, Tenerife (Spain); Moliner, R.; Lazaro, M.J. [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Rodriguez, J.L.; Pastor, E. [Facultad de Quimicas, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071, La Laguna, Tenerife (Spain)

    2009-01-15

    Novel nanostructured catalysts based on PtRu-MoO{sub x} nanoparticles supported on carbon nanofibers have been investigated for CO and methanol electrooxidation. Carbon nanofibers are prepared by thermocatalytic decomposition of methane (NF), and functionalized with HNO{sub 3} (NF.F). Electrocatalysts are obtained using a two-step procedure: (1) Pt and Ru are incorporated on the carbon substrates (Vulcan XC 72R, NF and NF.F), and (2) Mo is loaded on the PtRu/C samples. Differential electrochemical mass spectrometry (DEMS) analyses establish that the incorporation of Mo increases significantly the CO tolerance than respective binary counterparts. The nature of the carbon support affects considerably the stabilization of MoO{sub x} nanoparticles and also the performance in methanol electrooxidation. Accordingly, a significant increase of methanol oxidation is obtained in PtRu-MoO{sub x} nanoparticles supported on non-functionalized carbon nanofiber, in parallel with a large reduction of the Pt amount in comparison with binary counterparts and commercial catalyst. (author)

  11. Electrochemical performance of polygonized carbon nanofibers as anode materials for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    Jinjin Jiang; xiaolin Tang; Rui Wu; Haoqiang Lin; Meizhen Qu

    2013-01-01

    Carbon nanofibers with a polygonal cross section (P-CNFs) synthesized using a catalytic chemical vapor deposition (CCVD) technology have been investigated for potential applications in lithium batteries as anode materials.P-CNFs exhibit excellent high-rate capabilities.At a current density as high as 3.7 and 7.4A/g,P-CNFs can still deliver a reversible capacity of 198.4 and 158.2 mAh/g,respectively.To improve their first coulombic efficiency,carbon-coated P-CNFs were prepared through thermal vapor deposition (TVD) of benzene at 900 ℃.The electrochemical results demonstrate that appropriate amount of carbon coating can improve the first coulombic efficiency,the cycling stability and the rate performance of P-CNFs.After carbon coating,P-CNFs gain a weight increase approximately by 103 wt%,with its first coulombic efficiency increasing from 63.1 to 78.4%,and deliver a reversible capacity of 197.4mAh/g at a current density of 3.7 A/g.After dozens of cycles,there is no significant capacity degradation at both low and high current densities.

  12. TECHNICAL NOTE: A feasibility study of self-heating concrete utilizing carbon nanofiber heating elements

    Science.gov (United States)

    Chang, Christiana; Ho, Michelle; Song, Gangbing; Mo, Yi-Lung; Li, Hui

    2009-12-01

    This paper presents the development of an electric, self-heating concrete system that uses embedded carbon nanofiber paper as electric resistance heating elements. The proposed system utilizes the conductive properties of carbon fiber materials to heat a surface overlay of concrete with various admixtures to improve the concrete's thermal conductivity. The development and laboratory scale testing of the system were conducted for the various compositions of concrete containing, separately, carbon fiber, fly ash, and steel shavings as admixtures. The heating performances of these concrete mixtures with the carbon fiber heating element were experimentally obtained in a sub-freezing ambient environment in order to explore the use of such a system for deicing of concrete roadways. Analysis of electric power consumption, heating rate, and obtainable concrete surface temperatures under typical power loads was performed to evaluate the viability of a large scale implementation of the proposed heating system for roadway deicing applications. A cost analysis is presented to provide a comparison with traditional deicing methods, such as salting, and other integrated concrete heating systems.

  13. Covering vertically aligned carbon nanotubes with a multiferroic compound

    KAUST Repository

    Mahajan, Amit

    2014-10-30

    This work highlights the possible use of vertically-aligned multiwall carbon nanotubes (VA-MWCNTs) as bottom electrodes for microelectronics, for example for memory applications. As a proof of concept BiFeO3 (BFO) films were fabricated in-situ deposited on the surface of VA-MWCNTs by RF (radio frequency) magnetron sputtering. For in situ deposition temperature of 400 °C and deposition time up to 2 h, BFO films cover the MWCNTs and no damage occurs either in the film or MWCNTs. In spite of the macroscopic lossy polarization behaviour, the ferroelectric nature, domain structure and switching of these conformal BFO films was verified by piezo force microscopy. G type antiferromagnetic ordering with weak ferromagnetic ordering loop was proved for BFO films on VA-MWCNTs having a coercive field of 700 Oe.

  14. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    Science.gov (United States)

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-11-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  15. High Thermal and Electrical Conductivity of Template Fabricated P3HT/MWCNT Composite Nanofibers.

    Science.gov (United States)

    Smith, Matthew K; Singh, Virendra; Kalaitzidou, Kyriaki; Cola, Baratunde A

    2016-06-15

    Nanoporous alumina membranes are filled with multiwalled carbon nanotubes (MWCNTs) and then poly(3-hexylthiophene-2,5-diyl) (P3HT) melt, resulting in nanofibers with nanoconfinement induced coalignment of both MWCNT and polymer chains. The simple sonication process proposed here can achieve vertically aligned arrays of P3HT/MWCNT composite nanofibers with 3 wt % to 55 wt % MWCNT content, measured using thermogravimetric methods. Electrical and thermal transport in the composite nanofibers improves drastically with increasing carbon nanotube content where nanofiber thermal conductivity peaks at 4.7 ± 1.1 Wm(-1)K(-1) for 24 wt % MWCNT and electrical percolation occurs once 20 wt % MWCNT content is surpassed. This is the first report of the thermal conductivity of template fabricated composite nanofibers and the first proposed processing technique to enable template fabrication of composite nanofibers with high filler content and long aspect ratio fillers, where enhanced properties can also be realized on the macroscale due to vertical alignment of the nanofibers. These materials are interesting for thermal management applications due to their high thermal conductivity and temperature stability.

  16. A nucleation and growth model of vertically-oriented carbon nanofibers or nanotubes by plasma-enhanced catalytic chemical vapor deposition.

    Science.gov (United States)

    Cojocaru, C S; Senger, A; Le Normand, F

    2006-05-01

    Carbon nanofibers are grown by direct current and hot filaments-activated catalytic chemical vapor deposition while varying the power of the hot filaments. Observations of these carbon nanofibers vertically oriented on a SiO2 (8 nm thick)/Si(100) substrate covered with Co nanoparticles (10-15 nm particle size) by Scanning Electron and Transmission Electron Microscopies show the presence of a graphitic "nest" either on the surface of the substrate or at the end of the specific nanofiber that does not encapsulate the catalytic particle. Strictly in our conditions, the activation by hot filaments is required to grow nanofibers with a C2H2 - H2 gas mixture, as large amounts of amorphous carbon cover the surface of the substrate without using hot filaments. From these observations as well as data of the literature, it is proposed that the nucleation of carbon nanofibers occurs through a complex process involving several steps: carbon concentration gradient starting from the catalytic carbon decomposition and diffusion from the surface of the catalytic nanoparticles exposed to the activated gas and promoted by energetic ionic species of the gas phase; subsequent graphitic condensation of a "nest" at the interface of the Co particle and substrate. The large concentration of highly reactive hydrogen radicals mainly provided by activation with hot filaments precludes further spreading out of this interfacial carbon nest over the entire surface of the substrate and thus selectively orientates the growth towards the condensation of graphene over facets that are perpendicular to the surface. Carbon nanofibers can then be grown within the well-known Vapor-Liquid-Solid process. Thus the effect of energetic ions and highly reactive neutrals like atomic hydrogen in the preferential etching of carbon on the edge of graphene shells and on the broadening of the carbon nanofiber is underlined.

  17. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  18. Enhancing Crystallinity and Orientation by Hot-Stretching to Improve the Mechanical Properties of Electrospun Partially Aligned Polyacrylonitrile (PAN Nanocomposites

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Hou

    2011-04-01

    Full Text Available Partially aligned polyacrylonitrile (PAN-based nanofibers were electrospun from PAN and PAN/single-walled carbon nanotubes (SWNTs in a solution of dimethylformamide (DMF to make the nanofiber composites. The as-spun nanofibers were then hot-stretched in the oven to enhance its orientation and crystallinity. With the introduction of SWNTs and by the hot-stretched process, the mechanical properties will be enhanced correspondingly. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray scattering (XRD, differential scanning calorimetry (DSC, and the tensile test were used to characterize the microstructure and performances of the nanofibers. The orientation and crystallinity of the as-spun and hot-stretched nanofibers confirmed by X-ray have increased. Differential scanning calorimetry showed that the glass transition temperature of PAN increased about 3 °C by an addition of 0.75 wt% SWNTs indicating a strong interfacial interaction between PAN and SWNTs. The tensile strength and the modulus of the nanofibers increased revealing significant load transfer across the nanotube-matrix interface. For PAN nanofibers, the improved fiber alignment, orientation and crystallinity resulted in enhanced mechanical properties, such as the tensile strength and modulus of the nanofibers. It was concluded that the hot-stretched nanofiber and the PAN/SWNTs nanofibers can be used as a potential precursor to produce high-performance nanocomposites.

  19. Copper/zinc bimetal nanoparticles-dispersed carbon nanofibers: A novel potential antibiotic material.

    Science.gov (United States)

    Ashfaq, Mohammad; Verma, Nishith; Khan, Suphiya

    2016-02-01

    Copper (Cu) and zinc (Zn) nanoparticles (NPs) were asymmetrically distributed in carbon nanofibers (CNFs) grown on an activated carbon fiber (ACF) substrate by chemical vapor deposition (CVD). The CVD conditions were chosen such that the Cu NPs moved along with the CNFs during tip-growth, while the Zn NPs remained adhered at the ACF. The bimetal-ACF/CNF composite material was characterized by the metal NP release profiles, in-vitro hemolytic and antibacterial activities, and bacterial cellular disruption and adhesion assay. The synergetic effects of the bimetal NPs distributed in the ACFs/CNFs resulted from the relatively slower release of the Cu NPs located at the tip of the CNFs and faster release of the Zn NPs dispersed in the ACF. The Cu/Zn-grown ACFs/CNFs inhibited the growth of the Gram negative Escherichia coli, Gram positive Staphylococcus aureus, and Methicillin resistance Staphylococcus aureus bacterial strains, with superior efficiency (instant and prolonged inhibition) than the Cu or Zn single metal-grown ACFs/CNFs. The prepared bimetal-carbon composite material in this study has potential to be used in different biomedical applications such as wound healing and antibiotic wound dressing.

  20. Highly Sensitive Thin Film Sensor Based on Worm-like Carbon Nanofibers for Detection of Ammonia in Workplace

    Institute of Scientific and Technical Information of China (English)

    WANG Jia-zhi; CHEN Xing; LI Min-Qiang; LIU Jin-Huai

    2008-01-01

    A thin film sensor was fabricated using the mixture of worm-like carbon nanofibers (WCNF), which were synthesized using aluminium supported iron catalysts via chemical vapour deposition, and glass dust in proportion of 3 : 2, combined by drops of terpineol. The morphology of the catalyst, the worm-like carbon nanofibers and the film surface were investigated with the help of TEM and SEM. Low single-potential signal was employed to investigate gas sensitivity of the sensor to the deleterious ammonia, in atmospheric pressure at room temperature. The results suggest that the sensor has high sensitivity at low concentration (0.175-0.35 mg/m3), perfect reproducibility,and a fast response time (0.05 s) and restoration time (1 min).

  1. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO{sub 2}-coated carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Barrena, M.I., E-mail: ibarrena@quim.ucm.es [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain); Gomez de Salazar, J.M.; Soria, A.; Matesanz, L. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain)

    2011-11-15

    This work reported basically aims at understanding the extent of SiO{sub 2}-coated carbon nanofibers using two different sol-gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO{sub 2} precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

  2. Large-scale conversion of helical-ribbon carbon nanofibers to a variety of graphene-related materials

    OpenAIRE

    Lobato Ortega, Belén; Merino, C.; Barranco, V.; Álvarez Centeno, Teresa

    2016-01-01

    Helical-ribbon carbon nanofibers produced on an industrial scale were successfully converted in highly functionalized graphene nanoplatelets by using a slight modification of the Hummers oxidation method. The duration of the oxidative process severely affected the interlayer spacing in the resulting nanoplatelets and, consequently, they showed very different exfoliation behavior. Therefore, it was possible to obtain a variety of graphene-related products through their ultrasonication or therm...

  3. Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks

    Science.gov (United States)

    Lee, Jeonyoon; Stein, Itai Y.; Devoe, Mackenzie E.; Lewis, Diana J.; Lachman, Noa; Kessler, Seth S.; Buschhorn, Samuel T.; Wardle, Brian L.

    2015-02-01

    Here, we quantify the electron transport properties of aligned carbon nanotube (CNT) networks as a function of the CNT length, where the electrical conductivities may be tuned by up to 10× with anisotropies exceeding 40%. Testing at elevated temperatures demonstrates that the aligned CNT networks have a negative temperature coefficient of resistance, and application of the fluctuation induced tunneling model leads to an activation energy of ≈14 meV for electron tunneling at the CNT-CNT junctions. Since the tunneling activation energy is shown to be independent of both CNT length and orientation, the variation in electron transport is attributed to the number of CNT-CNT junctions an electron must tunnel through during its percolated path, which is proportional to the morphology of the aligned CNT network.

  4. Nanoporous Carbon Nanofibers Decorated with Platinum Nanoparticles for Non-Enzymatic Electrochemical Sensing of H2O2

    Directory of Open Access Journals (Sweden)

    Yang Li

    2015-11-01

    Full Text Available We describe the preparation of nanoporous carbon nanofibers (CNFs decorated with platinum nanoparticles (PtNPs in this work by electrospining polyacrylonitrile (PAN nanofibers and subsequent carbonization and binding of PtNPs. The fabricated nanoporous CNF-PtNP hybrids were further utilized to modify glass carbon electrodes and used for the non-enzymatic amperometric biosensor for the highly sensitive detection of hydrogen peroxide (H2O2. The morphologies of the fabricated nanoporous CNF-PtNP hybrids were observed by scanning electron microscopy, transmission electron microscopy, and their structure was further investigated with Brunauer–Emmett–Teller (BET surface area analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectrum. The cyclic voltammetry experiments indicate that CNF-PtNP modified electrodes have high electrocatalytic activity toward H2O2 and the chronoamperometry measurements illustrate that the fabricated biosensor has a high sensitivity for detecting H2O2. We anticipate that the strategies utilized in this work will not only guide the further design and fabrication of functional nanofiber-based biomaterials and nanodevices, but also extend the potential applications in energy storage, cytology, and tissue engineering.

  5. Mechanical, thermal and morphological characterization of polycarbonate/oxidized carbon nanofiber composites produced with a lean 2-step manufacturing process.

    Science.gov (United States)

    Lively, Brooks; Kumar, Sandeep; Tian, Liu; Li, Bin; Zhong, Wei-Hong

    2011-05-01

    In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry.

  6. Biocompatibility evaluation of electrospun aligned poly(propylene carbonate) nanofibrous scaffolds with peripheral nerve tissues and cells in vitro

    Institute of Scientific and Technical Information of China (English)

    WANG Yu; ZHAO Zhe; ZHAO Bin; QI Hong-xu; PENG Jiang; ZHANG Li; XU Wen-jing; HU Ping; LU Shi-bi

    2011-01-01

    Background Peripheral nerve regeneration across large gaps is clinically challenging. Scaffold design plays a pivotal role in nerve tissue engineering. Recently, nanofibrous scaffolds have proven a suitable environment for cell attachment and proliferation due to similarities of their physical properties to natural extracellular matrix. Poly(propylene carbonate)(PPC) nanofibrous scaffolds have been investigated for vascular tissue engineering. However, no reports exist of PPC nanofibrous scaffolds for nerve tissue engineering. This study aimed to evaluate the potential role of aligned and random PPC nanofibrous scaffolds as substrates for peripheral nerve tissue and cells in nerve tissue engineering. Methods Aligned and random PPC nanofibrous scaffolds were fabricated by electrospinning and their chemical characterization were carried out using scanning electron microscopy (SEM). Dorsal root ganglia (DRG) from Sprague-Dawley rats were cultured on the nanofibrous substrates for 7 days. Neurite outgrowth and Schwann-cell migration from DRG were observed and quantified using immunocytochemistry and SEM. Schwann cells derived from rat sciatic nerves were cultured in electrospun PPC scaffold-extract fluid for 24, 48, 72 hours and 7 days. The viability of Schwann cells was evaluated by 3-[4,5-dimethyl(thiazol-2-yl)-2,5-diphenyl] tetrazolium bromide (MTT) assay. Results The diameter of aligned and random fibers ranged between 800 nm and 1200 nm, and the thickness of the films was approximately 10-20 μm. Quantification of aligned fiber films revealed approximately 90% alignment of all fibers along the longitudinal axis. However, with random fiber films, the alignment of fibers was random through all angle bins. Rat DRG explants were grown on PPC nanofiber films for up to 1 week. On the aligned fiber films, the majority of neurite outgrowth and Schwann cell migration from the DRG extended unidirectionally, parallel to the aligned fibers.However, on the random fiber films

  7. Thermal−Electrical Character of in Situ Synthesized Polyimide-Grafted Carbon Nanofiber Composites

    Energy Technology Data Exchange (ETDEWEB)

    Arlen, Michael J.; Wang, David; Jacobs, J. David; Justice, Ryan; Trionfi, Aaron; Hsu, Julia W.P.; Schaffer, Dale; Tan, Loon-Seng; Vaia, Richard A. (Sandia); (UCIN); (AFRL)

    2008-12-09

    Notwithstanding the success of polymer-carbon nanotube (CNT) nanocomposites, a solid understanding of the impact of external perturbations, including temperature and stress, on the electrical response, its reproducibility, and the subsequent relationship to the topology of the percolative morphology and molecular details of the CNT-CNT contact junction is not complete. Using an in situ synthesis approach, two series of polymide (CP2)-carbon nanofiber (CNF) composites are prepared with quantitatively (small-angle X-ray scattering) comparable CNF dispersions, but differing in the structure of the CNF-polymer interface. Amino-functionalized CNFs (FCNFs) enable direct formation of CP2 grafts onto the CNFs, whereas pristine CNFs (PCNFs) result in a relatively weak interface between the carbon nanofiber and CP2 matrix. In general, low-frequency ac impedance measurements are well described by the percolation bond model, yielding a percolation threshold below 1 vol % (0.24 and 0.68 vol % for PCNF-CP2 and FCNF-CP2, respectively). However, the design of the interface is determined to be crucial for controlling the electrical behavior in four substantial ways: magnitude of the limiting conductivity, linearity of the I-V response, magnitude and direction of temperature-dependent resistivity, and reproducibility of the absolute value of the resistivity with thermal cycling. These observations are consistent with a direct CNF-CNF contact limiting transport in the PCNF-CP2 system, where the CP2 grafts onto the FCNF from a dielectric layer, limiting transport within the FCNF-CP2 system. Furthermore, the grafted CP2 chains on the FCNF reduce local polymer dewetting at the CNF surfaces when the temperature exceeds the CP2 glass transition. This appears to stabilize the structure of the percolation network and associated conductivity. The general behavior of these interfacial extremes (pristine and fully functionalized CNFs) set important bounds on the design of interface

  8. Imaging, spectroscopic, mechanical and biocompatibility studies of electrospun Tecoflex{sup ®} EG 80A nanofibers and composites thereof containing multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Macossay, Javier, E-mail: jmacossay@utpa.edu [Department of Chemistry, University of Texas-Pan American, Edinburg TX 78539 (United States); Sheikh, Faheem A. [Department of Chemistry, University of Texas-Pan American, Edinburg TX 78539 (United States); Nano-Bio Regenerative Medical Institute, College of Medicine, Hallym University, Chuncheon 200-702 (Korea, Republic of); Cantu, Travis; Eubanks, Thomas M.; Salinas, M. Esther; Farhangi, Chakavak S.; Ahmad, Hassan [Department of Chemistry, University of Texas-Pan American, Edinburg TX 78539 (United States); Hassan, M. Shamshi; Khil, Myung-seob [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Maffi, Shivani K. [Regional Academic Health Center-Edinburg (E-RAHC), Medical Research Division, 1214 W. Schunior St, Edinburg TX 78541 (United States); Department of Molecular Medicine, University of Texas Health Science Center, 15355 Lambda Dr. San Antonio TX 78245 (United States); Kim, Hern [Energy and Environment Fusion Technology Center, Department of Energy and Biotechnology, Myongji University, Yongin Kyonggi-do 449-728 (Korea, Republic of); Bowlin, Gary l. [Department of Biomedical Engineering, The University of Memphis, Memphis TN 38152 (United States)

    2014-12-01

    Highlights: • This work suggested the efficient use of MWCNTs to impart high mechanical properties to nanofibers and while maintaining the toxicity of the materials. • The mechanical properties of the nanofibers can be improved by introducing 2% of MWCNTs, above this point the mechanical property is reduced in nanofibers fabricated from Tecoflex{sup ®} EG 80A. • The presence of MWCNTs in the nanofibers reflecting the successful electrospining event can be ascertained by FT-IR, Raman, and TEM. • The nanofibers obtained while introducing MWCNTs represent no toxic behavior to cultured fibroblast. - Abstract: The present study discusses the design, development, and characterization of electrospun Tecoflex{sup ®} EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The Fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C–N and N–H bonds in polyurethanes are responsible for the interactions with MWCNTs. Furthermore, tensile testing indicated an increase in the Young's modulus of the nanofibers as the MWCNTs concentration was increased. Finally, NIH 3T3 fibroblasts were seeded on the obtained nanofibers, demonstrating cell biocompatibility and proliferation. Therefore, the results indicate the successful formation of polyurethane nanofibers with enhanced mechanical properties, and demonstrate their biocompatibility, suggesting their potential application in biomedical areas.

  9. Hierarchical Graphene-Containing Carbon Nanofibers for Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Dufficy, Martin K; Khan, Saad A; Fedkiw, Peter S

    2016-01-20

    We present a method to produce composite anodes consisting of thermally reduced graphene oxide-containing carbon nanofibers (TRGO/CNFs) via electrospinning a dispersion of polyacrylonitrile (PAN) and graphene oxide (GO) sheets in dimethylformamide followed by heat treatment at 650 °C. A range of GO (1-20 wt % GO relative to polymer concentration) was added to the polymer solution, with each sample comprising similar polymer chain packing and subsequent CNF microstructure, as assessed by X-ray diffraction. An increase from 0 to 20 wt % GO in the fibers led to carbonized nonwovens with enhanced electronic conductivity, as TRGO sheets conductively connected the CNFs. Galvanostatic half-cell cycling revealed that TRGO addition enhanced the specific discharge capacity of the fibers. The optimal GO concentration of 5 wt % GO enhanced first-cycle discharge capacities at C/24 rates (15.6 mA g(-1)) 150% compared to CNFs, with a 400% capacity increase at 2-C rates (750 mA g(-1)). We attribute the capacity enhancement to a high degree of GO exfoliation. The TRGO/CNFs also experienced no capacity fade after 200 cycles at 2-C rates. Impedance spectroscopy of the composite anodes demonstrated that charge-transfer resistances decreased as GO content increased, implying that high GO loadings result in more electrochemically active material.

  10. Vanadium nitride quantum dot/nitrogen-doped microporous carbon nanofibers electrode for high-performance supercapacitors

    Science.gov (United States)

    Wu, Yage; Ran, Fen

    2017-03-01

    In this article, vanadium nitride quantum dot/nitrogen-doped microporous carbon nanofibers (VNQD/CNF) is developed by a method of combination of electrostatic spinning and high-temperature calcination under the atmosphere of NH3: N2 = 3: 2 for high performance supercapacitors. VNQD dispersing into CNF, enrichment of N atom doped in carbon bulk, and abundant porous structure not only prevent the growth and aggregation of VN nanoparticles, improve electrical conductivity, wettability, and stability of the electrode materials, but also enhance fast migration of electrolyte ions during the electrochemical process. Thus, VNQD/CNF exhibits a high specific capacitance of 406.5 F g-1 at 0.5 A g-1 and a good rate capability with a capacitance retention of 75.1% at 5.0 A g-1. Additionally, VNQD/CNF as a negative electrode are combined with Ni(OH)2 as a positive electrode to fabricate the hybrid supercapacitor of VNQD/CNF//Ni(OH)2. Remarkably, at a power density of 774.6 W kg-1, the supercapacitor device delivers an ultrahigh energy density of 31.2 Wh kg-1.

  11. Direct synthesis of carbon nanofibers from South African coal fly ash.

    Science.gov (United States)

    Hintsho, Nomso; Shaikjee, Ahmed; Masenda, Hilary; Naidoo, Deena; Billing, Dave; Franklyn, Paul; Durbach, Shane

    2014-01-01

    Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings.

  12. Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes

    Directory of Open Access Journals (Sweden)

    Gemma Rius

    2015-01-01

    Full Text Available Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency.

  13. Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes.

    Science.gov (United States)

    Rius, Gemma; Lorenzoni, Matteo; Matsui, Soichiro; Tanemura, Masaki; Perez-Murano, Francesc

    2015-01-01

    Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO) is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM) has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT)-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF) as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency.

  14. The Leidenfrost temperature increase for impacting droplets on carbon-nanofiber surfaces.

    Science.gov (United States)

    Nair, Hrudya; Staat, Hendrik J J; Tran, Tuan; van Houselt, Arie; Prosperetti, Andrea; Lohse, Detlef; Sun, Chao

    2014-04-07

    Droplets impacting on a superheated surface can either exhibit a contact boiling regime, in which they make direct contact with the surface and boil violently, or a film boiling regime, in which they remain separated from the surface by their own vapor. The transition from the contact to the film boiling regime depends not only on the temperature of the surface and the kinetic energy of the droplet, but also on the size of the structures fabricated on the surface. Here we experimentally show that surfaces covered with carbon-nanofibers delay the transition to film boiling to much higher temperatures compared to smooth surfaces. We present physical arguments showing that, because of the small scale of the carbon fibers, they are cooled by the vapor flow just before the liquid impact, thus permitting contact boiling up to much higher temperatures than on smooth surfaces. We also show that as long as the impact is in the film boiling regime, the spreading factor of impacting droplets is consistent with the We(3/10) scaling (with We being the Weber number) as predicted for large We by a scaling analysis.

  15. Leidenfrost temperature increase for impacting droplets on carbon-nanofiber surfaces

    CERN Document Server

    Nair, Hrudya; Tran, Tuan; van Houselt, Arie; Prosperetti, Andrea; Lohse, Detlef; Sun, Chao

    2013-01-01

    Droplets impacting on a superheated surface can either exhibit a contact boiling regime, in which they make direct contact with the surface and boil violently, or a film boiling regime, in which they remain separated from the surface by their own vapor. The transition from the contact to the film boiling regime depends not only on the temperature of the surface and kinetic energy of the droplet, but also on the size of the structures fabricated on the surface. Here we experimentally show that surfaces covered with carbon-nanofibers delay the transition to film boiling to much higher temperature compared to smooth surfaces. We present physical arguments showing that, because of the small scale of the carbon fibers, they are cooled by the vapor flow just before the liquid impact, thus permitting contact boiling up to much higher temperatures than on smooth surfaces. We also show that, as long as the impact is in the film boiling regime, the spreading factor of impacting droplets follows the same $\\We^{3/10}$ sc...

  16. Carbon Nanofibers and Their Composites: A Review of Synthesizing, Properties and Applications

    Directory of Open Access Journals (Sweden)

    Lichao Feng

    2014-05-01

    Full Text Available Carbon nanofiber (CNF, as one of the most important members of carbon fibers, has been investigated in both fundamental scientific research and practical applications. CNF composites are able to be applied as promising materials in many fields, such as electrical devices, electrode materials for batteries and supercapacitors and as sensors. In these applications, the electrical conductivity is always the first priority need to be considered. In fact, the electrical property of CNF composites largely counts on the dispersion and percolation status of CNFs in matrix materials. In this review, the electrical transport phenomenon of CNF composites is systematically summarized based on percolation theory. The effects of the aspect ratio, percolation backbone structure and fractal characteristics of CNFs and the non-universality of the percolation critical exponents on the electrical properties are systematically reviewed. Apart from the electrical property, the thermal conductivity and mechanical properties of CNF composites are briefly reviewed, as well. In addition, the preparation methods of CNFs, including catalytic chemical vapor deposition growth and electrospinning, and the preparation methods of CNF composites, including the melt mixing and solution process, are briefly introduced. Finally, their applications as sensors and electrode materials are described in this review article.

  17. Cell studies of hybridized carbon nanofibers containing bioactive glass nanoparticles using bone mesenchymal stromal cells

    Science.gov (United States)

    Zhang, Xiu-Rui; Hu, Xiao-Qing; Jia, Xiao-Long; Yang, Li-Ka; Meng, Qing-Yang; Shi, Yuan-Yuan; Zhang, Zheng-Zheng; Cai, Qing; Ao, Yin-Fang; Yang, Xiao-Ping

    2016-12-01

    Bone regeneration required suitable scaffolding materials to support the proliferation and osteogenic differentiation of bone-related cells. In this study, a kind of hybridized nanofibrous scaffold material (CNF/BG) was prepared by incorporating bioactive glass (BG) nanoparticles into carbon nanofibers (CNF) via the combination of BG sol-gel and polyacrylonitrile (PAN) electrospinning, followed by carbonization. Three types (49 s, 68 s and 86 s) of BG nanoparticles were incorporated. To understand the mechanism of CNF/BG hybrids exerting osteogenic effects, bone marrow mesenchymal stromal cells (BMSCs) were cultured directly on these hybrids (contact culture) or cultured in transwell chambers in the presence of these materials (non-contact culture). The contributions of ion release and contact effect on cell proliferation and osteogenic differentiation were able to be correlated. It was found that the ionic dissolution products had limited effect on cell proliferation, while they were able to enhance osteogenic differentiation of BMSCs in comparison with pure CNF. Differently, the proliferation and osteogenic differentiation were both significantly promoted in the contact culture. In both cases, CNF/BG(68 s) showed the strongest ability in influencing cell behaviors due to its fastest release rate of soluble silicium-relating ions. The synergistic effect of CNF and BG would make CNF/BG hybrids promising substrates for bone repairing.

  18. High-Performance Supercapacitor Electrode Materials from Cellulose-Derived Carbon Nanofibers.

    Science.gov (United States)

    Cai, Jie; Niu, Haitao; Li, Zhenyu; Du, Yong; Cizek, Pavel; Xie, Zongli; Xiong, Hanguo; Lin, Tong

    2015-07-15

    Nitrogen-functionalized carbon nanofibers (N-CNFs) were prepared by carbonizing polypyrrole (PPy)-coated cellulose NFs, which were obtained by electrospinning, deacetylation of electrospun cellulose acetate NFs, and PPy polymerization. Supercapacitor electrodes prepared from N-CNFs and a mixture of N-CNFs and Ni(OH)2 showed specific capacitances of ∼236 and ∼1045 F g(-1), respectively. An asymmetric supercapacitor was further fabricated using N-CNFs/Ni(OH)2 and N-CNFs as positive and negative electrodes. The supercapacitor device had a working voltage of 1.6 V in aqueous KOH solution (6.0 M) with an energy density as high as ∼51 (W h) kg(-1) and a maximum power density of ∼117 kW kg(-1). The device had excellent cycle lifetime, which retained ∼84% specific capacitance after 5000 cycles of cyclic voltammetry scans. N-CNFs derived from electrospun cellulose may be useful as an electrode material for development of high-performance supercapacitors and other energy storage devices.

  19. Enhanced activity and selectivity of carbon nanofiber supported Pd catalysts for nitrite reduction.

    Science.gov (United States)

    Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R; Werth, Charles J

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment.

  20. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  1. Synthesis and characterisation of epoxy resins reinforced with carbon nanotubes and nanofibers.

    Science.gov (United States)

    Prolongo, S G; Gude, M R; Ureña, A

    2009-10-01

    Epoxy nanocomposites were fabricated using two kinds of nanofiller, amino-functionalized multi-walled carbon nanotubes (CNTs) and non-treated long carbon nanofibers (CNFs). The non-cured mixtures were analysed through viscosity measurements. The effect of the nanoreinforcement on the curing process was determined by differential scanning calorimetry. Finally, the characterisation of cured nanocomposites was carried out studying their thermo-mechanical and electrical behaviour. At room temperature, the addition of CNTs causes a viscosity increase of epoxy monomer much more marked than the introduction of CNFs due to their higher specific area. It was probed that in that case exists chemical reaction between amino-functionalized CNTs and the oxirane rings of epoxy monomer. The presence of nanoreinforcement induces a decrease of curing reaction rate and modifies the epoxy conversion reached. The glass transition temperature of the nanocomposites decreases with the contents of CNTs and CNFs added, which could be related to plasticization phenomena of the nanoreinforcements. The storage modulus of epoxy resin significantly increases with the addition of CNTs and CNFs. This augment is higher with amino-functionalized CNTs due, between other reasons, to the stronger interaction with the epoxy matrix. The electrical conductivity is greatly increased with the addition of CNTs and CNFs. In fact, the percolation threshold is lower than 0.25 wt% due to the high aspect ratio of the used nanoreinforcements.

  2. Electrospun carbon nanofibers/electrocatalyst hybrids as asymmetric electrodes for vanadium redox flow battery

    Science.gov (United States)

    Wei, Guanjie; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei

    2015-05-01

    To improve the electrochemical activity of polyacrylonitrile (PAN)-based electrospun carbon nanofibers (ECNFs) toward vanadium redox couples, the multi-wall carbon nanotubes (CNTs) and Bi-based compound as electrocatalyst have been embedded in the ECNFs to make composite electrode, respectively. The morphology and electrochemical properties of pristine ECNFs, CNTs/ECNFs and Bi/ECNFs have been characterized. Among the three kinds of electrodes, the CNTs/ECNFs show best electrochemical activity toward VO2+/VO2+ redox couple, while the Bi/ECNFs present the best electrochemical activity toward V2+/V3+ redox couple. Furthermore, the high overpotential of hydrogen evolution on Bi/ECNFs makes the side-reaction suppressed. Because of the large property difference between the two composite electrodes, the CNTs/ECNFs and Bi/ECNFs are designed to act as positive and negative electrode for vanadium redox flow battery (VRFB), respectively. It not only does improve the kinetics of two electrode reactions at the same time, but also reduce the kinetics difference between them. Due to the application of asymmetric electrodes, performance of the cell is improved greatly.

  3. Effect of carbon nanofiber addition in the mechanical properties and durability of cementitious materials

    Directory of Open Access Journals (Sweden)

    Galao, O.

    2012-09-01

    Full Text Available This paper reports on recent work that is directed at studying the changes in the mechanical properties of Portland cement based mortars due to the addition of carbon nanofiber (CNF. Both flexural and compression strength has been determined and related to the CNF addition to the mix, to the curing time and to the porosity and density of the matrix. Also, corrosion of embedded steel rebars in CNF cement pastes exposed to carbonation and chloride attacks has been investigated. The increase in CNF addition implies higher corrosion intensity and higher levels of mechanical properties.En este artículo se han estudiado los cambios en las propiedades mecánicas de los morteros de cemento Portland debido a la adición de nanofibras de carbono (NFC. Se han determinado las resistencias a flexotracción y a compresión de los morteros en relación a la cantidad de NFC añadidas a la mezcla, al tiempo de curado y a la porosidad y densidad de los mismos. Además se han investigado los niveles de corrosión de barras de acero embebidas en pastas de cemento con NFC expuestos al ataque por carbonatación y por ingreso de cloruros. El aumento en el porcentaje de NFC añadido se traduce en un aumento la intensidad de corrosión registrada y una mejora de las propiedades mecánicas.

  4. Direct synthesis of carbon nanofibers from South African coal fly ash

    Science.gov (United States)

    Hintsho, Nomso; Shaikjee, Ahmed; Masenda, Hilary; Naidoo, Deena; Billing, Dave; Franklyn, Paul; Durbach, Shane

    2014-08-01

    Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings.

  5. Aligned carbon nanotube thin films for DNA electrochemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Berti, F. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy); Lozzi, L. [Department of Physics, University of L' Aquila, Coppito, L' Aquila 67100 (Italy); Palchetti, I. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy); Santucci, S. [Department of Physics, University of L' Aquila, Coppito, L' Aquila 67100 (Italy); Marrazza, G. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy)], E-mail: giovanna.marrazza@unifi.it

    2009-09-01

    Carbon nanotubes are interesting materials for DNA electrochemical sensing due to their unique electric properties: high surface area, fast heterogeneous electron transfer, and electrochemical stability. In this work aligned Carbon NanoTube (CNT) thin films were designed and tested as candidate platforms for DNA immobilization and for the development of an electrochemical genosensor. The films were prepared by Chemical Vapor Deposition (CVD) using acetylene and ammonia as precursor gases and nickel particles as catalyst. A preliminary electrochemical characterization was performed using cyclic voltammetry since, so far, these films have been used only for gas sensing. The surfaces were then covalently functionalized with a DNA oligonucleotide probe, complementary to the sequence of the most common inserts in the GMOs: the Promoter 35S. The genosensor format involved the immobilization of the probe onto the sensor surface, the hybridization with the target-sequence and the electrochemical detection of the duplex formation. Careful attention was paid to the probe immobilization conditions in order to minimize the signal due to non-specifically adsorbed sequences. For the detection of the hybridization event both label-free and enzyme-labelled methods were investigated. In case of the enzyme-labelled method a target concentration at nanomolar level can be easily detected, with a linear response from 50 nM to 200 nM, whereas the label-free method showed a linear response between 0.5 {mu}M and 10 {mu}M. The reproducibility was 11% and 20% with the enzyme-labelled method and the label-free method, respectively. The batch-to-batch reproducibility of the different sensors was also evaluated.

  6. Modelling clustering of vertically aligned carbon nanotube arrays

    Science.gov (United States)

    Schaber, Clemens F.; Filippov, Alexander E.; Heinlein, Thorsten; Schneider, Jörg J.; Gorb, Stanislav N.

    2015-01-01

    Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications. PMID:26464787

  7. Hydrodynamic Helical Orientations of Nanofibers in a Vortex

    Directory of Open Access Journals (Sweden)

    Akihiko Tsuda

    2014-05-01

    Full Text Available In this review article, I report our recent studies on spectroscopic visualizations of macroscopic helical alignments of nanofibers in vortex flows. Our designed supramolecular nanofibers, formed through self-assemblies of dye molecules, helically align in torsional flows of a vortex generated by mechanical rotary stirring of the sample solutions. The nanofiber, formed through bundling of linear supramolecular polymers, aligns equally in right- and left-handed vortex flows. However, in contrast, a one-handedly twisted nanofiber, formed through helical bundling of the supramolecular polymers, shows unequal helical alignments in these torsional flows. When the helical handedness of the nanofiber matches that of the vortex flow, the nanofiber aligns more efficiently in the flowing fluid. Such phenomena are observed not only with the artificial helical supramolecular nanofibers but also with biological nanofibers such as double-stranded DNA.

  8. Effectiveness of electromagnetic interference shielding of carbon nanofiber/poly(vinylidene fluoride) composites as a function of heat treatment temperature and time

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M.S.; Lee, B.O.; Woo, W.J. [Myoungji Univeristy, Yongin (Korea); An, K.H. [Agency for Technology and Standards, Kwacheon (Korea)

    2001-05-01

    The electromagnetic interference (EMI) shielding effectiveness (SE) of poly(vinylidene fluoride) (PVDF) composites was investigated using carbon nanofiber fillers prepared by catalytic chemical vapor deposition of various carbon-containing gases over Ni and Ni-Cu catalysts. The electrical conductivity of carbon nanofiber which was regarded as the key property of filler for the application of EMI shielding ranged from 4.2 to 22.4 S/cm at a pressure of 10000 psi. The electrical conductivity of carbon nanofiber/PVDF composites ranged from 0.22 to 2.46 S/cm and the EMI SE of those was in the range of 2{approx}13 dB. The electrical conductivity of carbon nanofibers increased with the increase in heat treatment temperature and time, while the electrical conductivity of the composites increased rapidly at the initial heat treatment and then approached a certain value with the further increase of heat treatment. The SE of the composites showed a maximum at the medium heat treatment and was proportional to the electrical conductivity of the composites. It was concluded that the specific surface area of carbon nanofibers decreased with the continual heat treatment and the specific surface area of filler was an important factor for the SE of the composites. (author). 16 refs., 4 tabs., 5 figs.

  9. Nanoscratch technique for aligning multiwalled carbon nanotubes synthesized by the arc discharge method in open air

    Indian Academy of Sciences (India)

    A Joseph Berkmans; M Jagannatham; Prathap Haridoss

    2015-08-01

    Horizontally aligned and densely packed multiwalled carbon nanotubes (MWCNTs) were synthesized in an open air, without the need for a controlled atmosphere, using a rotating cathode arc discharge method with the help of a metal scraper. The physical force exerted by the scraper results in in-situ alignment of MWCNTs along the direction of scrape marks. This strategy, which enables the alignment of nanotubes in a controlled fashion to any length and direction of interest, was examined to determine the force required to align a nanotube. A model is developed to understand the alignment process. Using the nanoscratch technique to mimic this strategy, and incorporating the data obtained from the nanoscratch technique into the model developed, the minimum force required to align a MWCNT, as well as the energy required to align a gram of nanotubes, has been estimated. The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs.

  10. Simultaneous alignment and micropatterning of carbon nanotubes using modulated magnetic field

    Directory of Open Access Journals (Sweden)

    Kaoru Tsuda and Yoshio Sakka

    2009-01-01

    Full Text Available We report simultaneous alignment and micropatterning of carbon nanotubes (CNTs using a high magnetic field. It is important to prepare well-dispersed CNTs for alignment and patterning because CNT aggregation obstructs alignment. In magnetic field, highly anisotropic CNTs rotate in the direction stabilized in energy. Owing to their diamagnetic nature, CNTs suspended in a liquid medium are trapped in a weak magnetic field generated by a field modulator; meanwhile, they align to the applied strong magnetic field. The alignment has been achieved not only in polymers but also in ceramic and silicone composites.

  11. Free-Standing Thin Webs of Activated Carbon Nanofibers by Electrospinning for Rechargeable Li-O2 Batteries.

    Science.gov (United States)

    Nie, Hongjiao; Xu, Chi; Zhou, Wei; Wu, Baoshan; Li, Xianfeng; Liu, Tao; Zhang, Huamin

    2016-01-27

    Free-standing activated carbon nanofibers (ACNF) were prepared through electrospinning combining with CO2 activation and then used for nonaqueous Li-O2 battery cathodes. As-prepared ACNF based cathode was loosely packed with carbon nanofibers complicatedly overlapped. Owing to some micrometer-sized pores between individual nanofibers, relatively high permeability of O2 across the cathode becomes feasible. Meanwhile, the mesopores introduced by CO2 activation act as additional nucleation sites for Li2O2 formation, leading to an increase in the density of Li2O2 particles along with a size decrease of the individual particles, and therefore, flake-like Li2O2 are preferentially formed. In addition, the free-standing structure of ACNF cathode eliminates the side reactions about PVDF. As a result, the Li-O2 batteries with ACNF cathodes showed increased discharge capacities, reduced overpotentials, and longer cycle life in the case of full discharge and charge operation. This provides a novel pathway for the design of cathodes for Li-O2 battery.

  12. Fabrication of a carbon nanofiber sheet as a micro-porous layer for proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Qiongjuan; Wang, Jiong; Lu, Yonggen [College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Biao; Wang, Huaping [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); College of Material Science and Engineering, Donghua University, Shanghai 201620 (China)

    2010-12-15

    A carbon nanofiber sheet (CNFS) has been prepared by electrospinning, stabilisation and subsequent carbonisation processes. Imaging with scanning electron microscope (SEM) indicates that the CNFS is formed by nonwoven nanofibers with diameters between 400 and 700 nm. The CNFS, with its three-dimensional pores, shows excellent electrical conductivity and hydrophobicity. In addition, it is found that the CNFS can be successfully applied as a micro-porous layer (MPL) in the cathode gas diffusion layer (GDL) of a proton exchange membrane fuel cell (PEMFC). The GDL with the CNFS as a MPL has higher gas permeability than a conventional GDL. Moreover, the resultant cathode GDL exhibits excellent fuel cell performance with a higher peak power density than that of a cathode GDL fabricated with a conventional MPL under the same test condition. (author)

  13. Modulating the forces between self-assembling molecules to control the shape of vesicles and the mechanics and alignment of nanofiber networks

    Science.gov (United States)

    Greenfield, Megan Ann

    One of the great challenges in supramolecular chemistry is the design of molecules that can self-assemble into functional aggregates with well-defined three-dimensional structures and bulk material properties. Since the self-assembly of nanostructures is greatly influenced by both the nature of the self-assembling components and the environmental conditions in which the components assemble, this work explores how changes in the molecular design and the environment affect the properties of self-assembled structures. We first explore how to control the mechanical properties of self-assembled fibrillar networks by changing environmental conditions. We report here on how changing pH, screening ions, and solution temperature affect the gelation, stiffness, and response to deformation of peptide amphiphile gels. Although the morphology of PA gels formed by charge neutralization and salt-mediated charge screening are similar by electron microscopy, rheological measurements indicate that the calcium-mediated ionic bridges in CaCl2-PA gels form stronger intra- and inter-fiber crosslinks than the hydrogen bonds formed by the protonated carboxylic acid residues in HCl-PA gels. In contrast, the structure of PA gels changes drastically when the PA solution is annealed prior to gel formation. Annealed PA solutions are birefringent and can form viscoelastic strings of aligned nanofibers when manually dragged across a thin film of CaCl2. These aligned arrays of PA nanofibers hold great promise in controlling the orientation of cells in three-dimensions. Separately, we applied the principles of molecular design to create buckled membrane nanostructures that mimic the shape of viruses. When oppositely charged amphiphilic molecules are mixed they can form vesicles with a periodic two-dimensional ionic lattice that opposes the membrane's natural curvature and can result in vesicle buckling. Our results demonstrate that a large +3 to -1 charge imbalance between the cationic and anionic

  14. Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol-based nanocomposite material for lithium-ion electrolyte battery separator.

    Science.gov (United States)

    Sharma, Ajit K; Khare, Prateek; Singh, Jayant K; Verma, Nishith

    2013-04-01

    A novel nanocomposite polyvinyl alcohol precursor-based material dispersed with the web of carbon microfibers and carbon nanofibers is developed as lithium (Li)-ion electrolyte battery separator. The primary synthesis steps of the separator material consist of esterification of polyvinyl acetate to produce polyvinyl alcohol gel, ball-milling of the surfactant dispersed carbon micro-nanofibers, mixing of the milled micron size (~500 nm) fibers to the reactant mixture at the incipience of the polyvinyl alcohol gel formation, and the mixing of hydrophobic reagents along with polyethylene glycol as a plasticizer, to produce a thin film of ~25 μm. The produced film, uniformly dispersed with carbon micro-nanofibers, has dramatically improved performance as a battery separator, with the ion conductivity of the electrolytes (LiPF6) saturated film measured as 0.119 S-cm(-1), approximately two orders of magnitude higher than that of polyvinyl alcohol. The other primary characteristics of the produced film, such as tensile strength, contact angle, and thermal stability, are also found to be superior to the materials made of other precursors, including polypropylene and polyethylene, discussed in the literature. The method of producing the films in this study is novel, simple, environmentally benign, and economically viable.

  15. Effects of Thickness and Amount of Carbon Nanofiber Coated Carbon Fiber on Improving the Mechanical Properties of Nanocomposites

    Directory of Open Access Journals (Sweden)

    Ferial Ghaemi

    2016-01-01

    Full Text Available In the current study, carbon nanofibers (CNFs were grown on a carbon fiber (CF surface by using the chemical vapor deposition method (CVD and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP composite were investigated. To obtain an optimum surface area, thickness, and yield of the CNFs, the parameters of the chemical vapor deposition (CVD method, such as catalyst concentration, reaction temperature, reaction time, and hydrocarbon flow rate, were optimized. It was observed that the optimal surface area, thickness, and yield of the CNFs caused more adhesion of the fibers with the PP matrix, which enhanced the composite properties. Besides this, the effectiveness of reinforcement of fillers was fitted with a mathematical model obtaining good agreement between the experimental result and the theoretical prediction. By applying scanning electronic microscope (SEM, transmission electron microscope (TEM, and Raman spectroscopy, the surface morphology and structural information of the resultant CF-CNF were analyzed. Additionally, SEM images and a mechanical test of the composite with a proper layer of CNFs on the CF revealed not only a compactness effect but also the thickness and surface area roles of the CNF layers in improving the mechanical properties of the composites.

  16. Ultrafast Lithium Storage Using Antimony-Doped Tin Oxide Nanoparticles Sandwiched between Carbon Nanofibers and a Carbon Skin.

    Science.gov (United States)

    An, Geon-Hyoung; Lee, Do-Young; Lee, Yu-Jin; Ahn, Hyo-Jin

    2016-11-09

    Metal oxides as anode materials for Li-ion batteries (LIBs) are of significant interest to many potential technologies because of their high theoretical capacity value, low price, and environmentally friendly features. In spite of these considerable benefits and ongoing progress in the field, momentous challenges exist, related with structural disintegration due to volume expansion of electrode materials. This leads to rapid capacity decline and must be resolved in order to progress for realistic utilization of LIBs with ultrafast cycling stability. This article proposes a novel architecture of Sb-doped SnO2 nanoparticles sandwiched between carbon nanofiber and carbon skin (CNF/ATO/C) using electrospinning and hydrothermal methods. The CNF/ATO/C exhibits superb electrochemical behavior such as high specific capacity and outstanding cycling stability (705 mA h g(-1) after 100 cycles), outstanding high-rate performance (411 mA h g(-1) at 2000 mA g(-1)), and ultrafast cycling stability (347 mA h g(-1) at 2000 mA g(-1) after 100 cycles), which is high compared to any reported value using SnO2-based anode materials. Thus, this unique architecture furnishes profitable effects, including electroactive sites, structural stability, and electrical conductivity, which can potentially be realizes for ultrafast LIBs.

  17. Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

    Science.gov (United States)

    Li, Xiaona; Chen, Shuo; Fan, Xinfei; Quan, Xie; Tan, Feng; Zhang, Yaobin; Gao, Jinsuo

    2015-06-01

    Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions.

  18. Growth of carbon nanofiber coatings on nickel thin films on fused silica by catalytic thermal chemical vapor deposition: On the use of titanium, titanium–tungsten and tantalum as adhesion layers

    NARCIS (Netherlands)

    Thakur, D.B.; Tiggelaar, R.M.; Gardeniers, J.G.E.; Lefferts, L.; Seshan, K.

    2009-01-01

    Coatings of carbon nanofiber (CNF) layers were synthesized on fused silica substrates using a catalytic thermal chemical vapor deposition process (C-TCVD). The effects of various adhesion layers–titanium, titanium–tungsten and tantalum–under the nickel thin film on the attachment of carbon nanofiber

  19. Novel injectable biomimetic hydrogels with carbon nanofibers and self assembled rosette nanotubes for myocardial applications.

    Science.gov (United States)

    Meng, Xiangling; Stout, David A; Sun, Linlin; Beingessner, Rachel L; Fenniri, Hicham; Webster, Thomas J

    2013-04-01

    The objective of the present in vitro study was to investigate cardiomyocyte functions, specifically their adhesion and proliferation, on injectable scaffolds containing RNT (rosette nanotubes) and CNF (carbon nanofibers) in a pHEMA (poly(2-hydroxyethyl methacrylate)) hydrogel to determine their potential for myocardial tissue engineering applications. RNTs are novel biocompatible nanomaterials assembled from synthetic analogs of DNA bases guanine and cytosine that self-assemble within minutes when placed in aqueous solutions at body temperatures. These materials could potentially improve cardiomyocyte functions and solidification time of pHEMA and CNF composites. Because heart tissue is conductive, CNFs were added to pHEMA to increase the composite's conductivity. Our results showed that cardiomyocyte density increased after 4 h, 1 day, and 3 days with greater amounts of CNFs and greater amounts of RNTs in pHEMA (up to 10 mg mL(-1) CNFs and 0.05 mg mL(-1) RNTs). Factors that may have increased cardiomyocyte functions include greater wettability, conductivity, and an increase in surface nanoroughness with greater amounts of CNFs and RNTs. In effect, contact angles measured on the surface of the composites decreased while the conductivity and surface roughness increased as CNFs and RNTs content increased. Lastly, the ultimate tensile modulus decreased for composites with greater amounts of CNFs. In summary, the properties of these injectable composites make them promising candidates for myocardial tissue engineering applications and should be further studied.

  20. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials.

    Science.gov (United States)

    Borrell, Amparo; García-Moreno, Olga; Torrecillas, Ramón; García-Rocha, Victoria; Fernández, Adolfo

    2012-02-01

    Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (-150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  1. Post-treatment method for improving field emission from carbon nanotubes/nanofibers

    Institute of Scientific and Technical Information of China (English)

    GUO Ping-sheng; SUN Zhuo; ZHENG Zhi-hao

    2006-01-01

    A novel post-treatment method is reported for improving the field emission characteristics of screen-printed carbon nanotubes/nanofibers (CNTs/CNFs) cathodes.After the treatment at the temperature of 500℃ in H2 and C2H2 gas for 20 minutes,the CNTs/CNFs cathodes exhibit much better field emission properties than those untreated.The emission current increases from 0.02 mA/cm2 to 0.5 mA/cm2 at 3.9 V/μm with a decrease in the turn-on field from 2.4 V to 1.8 V ,and the emission site density is increased by almost four orders in magnitude.The enhanced field emission of treated CNTs/CNFs cathodes is attributed to the appearance of a large number of exposed CNTs/CNFs caused by heat treatment.This surface morphology is very favorable for the electron field emission.

  2. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

    Science.gov (United States)

    Borrell, Amparo; García-Moreno, Olga; Torrecillas, Ramón; García-Rocha, Victoria; Fernández, Adolfo

    2012-02-01

    Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (-150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  3. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

    Directory of Open Access Journals (Sweden)

    Amparo Borrell, Olga García-Moreno, Ramón Torrecillas, Victoria García-Rocha and Adolfo Fernández

    2012-01-01

    Full Text Available Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (−150 to 450 °C. The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  4. Physicochemical and electrochemical properties of carbon nanotube/graphite nanofiber hybrid nanocomposites for supercapacitor

    Science.gov (United States)

    Ramli, Nurul Infaza Talalah; Abdul Rashid, Suraya; Sulaiman, Yusran; Mamat, Md Shuhazlly; Mohd Zobir, Syazwan Afif; Krishnan, Shutesh

    2016-10-01

    This work reports the combination of graphitic nanofibers (GNF) and carbon nanotubes (CNT) as the electrode material for supercapacitors. The hybrid CNT/GNF was prepared via a synthesis route that involved simple sonication and stirring. The loading of CNT was varied from 5 to 40% weight percentages. A specific capacitance of 174 Fg-1 has been obtained for 20 wt% CNT loading at 50 mV F g-1th 1 M H2SO4 aqueous solution as the electrolyte. The addition of 20 wt% CNT raised the specific capacitance by 87% more than the GNF electrodes. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscope (TEM) reveals the random entanglement of CNT and GNF that create diffusion paths for ion transportation. Conformational changes were monitored by Raman spectroscopy, where two dominant peaks (D and G) showed strong intensities and sharp profiles. X-ray Diffraction spectroscopy (XRD) confirmed the purity of CNT/GNF hybrid nanocomposites. 20 wt% of CNT addition also shows an outstanding thermal stability. The marked improvement of the hybrid performance was attributed to the high conductivity of the two constituent materials, coupled with sufficient accessible active sites for electrochemical reactions that resulted in a synergistic behavior of the materials.

  5. Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires for lithium ion batteries

    Science.gov (United States)

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-05-01

    Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires (CuO/CNF) as anodes for lithium ion batteries were prepared by coating the Cu2(NO3)(OH)3 on the surface of conductive and elastic CNF via electrophoretic deposition (EPD), followed by thermal treatment in air. The CuO shell stacked with nanoparticles grows radially toward the CNF core, which forms hierarchically mesoporous three-dimensional (3D) coaxial shell-core structure with abundant inner spaces in nanoparticle-stacked CuO shell. The CuO shells with abundant inner spaces on the surface of CNF and high conductivity of 1D CNF increase mainly electrochemical rate capability. The CNF core with elasticity plays an important role in strongly suppressing radial volume expansion by inelastic CuO shell by offering the buffering effect. The CuO/CNF nanowires deliver an initial capacity of 1150 mAh g-1 at 100 mA g-1 and maintain a high reversible capacity of 772 mAh g-1 without showing obvious decay after 50 cycles.

  6. Flexible supercapacitors based on low-cost tape casting of high dense carbon nanofibers

    Science.gov (United States)

    Daraghmeh, Allan; Hussain, Shahzad; Servera, Llorenç; Xuriguera, Elena; Blanes, Mireia; Ramos, Francisco; Cornet, Albert; Cirera, Albert

    2017-02-01

    This experimental study, reports the use of flexible tape casting of dense carbon nanofiber (CNFs) alone and in hybrid structure with MnO2 for supercapacitor applications. Different electrolyte concentrations of potassium hydroxide (KOH) were tested and it was founded that mild concentrated electrolyte, like 9 M KOH, provides higher specific capacitance 38 F g‑1 at a scan rate of 5 mV s‑1. Electrochemical impedance spectroscopy (EIS) measurements explain that the solution resistance and the charge transfer resistance is higher for 3 M KOH concentrations and lower for 6 M KOH concentrations. Afterwards a novel, fast and simple method is adopted to achieve a hybrid nanostructure of CNFs/MnO2 with various KMnO4 ratios. The hybrid supercapacitor, having loaded a mass of 0.0003 g MnO2 as a thin film, delivers a highest specific capacitance of 812 F g‑1 at a scan rate 5 mV s‑1. Charge/discharge cycling stability at current density of 7.9 A g‑1 demonstrates larger specific capacitance 303 F g‑1 and stability. Furthermore, the hybrid supercapacitor can deliver specific energy (72.4 Wh kg‑1) at specific power (3.44 kW kg‑1). Specific surface area increase from 68 m2 g‑1 for CNFs to 240 m2 g‑1 for CNFs/MnO2.

  7. A three-dimensionally chitin nanofiber/carbon nanotube hydrogel network for foldable conductive paper.

    Science.gov (United States)

    Chen, Chuchu; Yang, Chuang; Li, Suiyi; Li, Dagang

    2015-12-10

    We reported a highly conductive nanocomposite made with multiwalled carbon nanotubes (MWCNTs) and chitin nanofibers (ChNFs). The MWCNTs were dispersed into ChNFs by the simple process of vacuum-filtration, forming a three-dimensional network structure. In this approach, MWCNT acted as a filler to introduce electron channel paths throughout the ChNF skeleton. And then, a hybrid hydrogel system (20 wt.% NaOH, -18 °C) was applied to prepare the ChNF/MWCNT gel-film followed with drying process. It is found that the resultant ChNF/MWCNT gel-film exposed much more MWCNT areas forming denser structure due to the shrinking of ChNFs after the gelation treatment. Compared with ChNF/MWCNT film, the one treated under hydrogel system (ChNF/MWCNT gel-film) exhibited almost twice higher conductivity (9.3S/cm for 50 wt.% MWCNTs in gel-film; whereas 4.7S/cm for 50 wt.% MWCNTs in film). Moreover, the facile and low-cost of this conductive paper may have great potential in development of foldable electronic devices.

  8. Superemission in vertically-aligned single-wall carbon nanotubes

    Science.gov (United States)

    Khmelinskii, Igor; Makarov, Vladimir

    2016-09-01

    Presently we used two samples of vertically aligned single-wall carbon nanotubes (VA SWCNTs) with parallelepiped geometry, sized 0.02 cm × 0.2 cm × 1.0 cm and 0.2 cm × 0.2 cm × 1.0 cm. We report absorption and emission properties of the VA SWCNTs, including strong anisotropy in both their absorption and emission spectra. We found that the emission spectra extend from the middle-IR range to the near-IR range, with such extended spectra being reported for the first time. Pumping the VA SWCNTs in the direction normal to their axis, superemission (SE) was observed in the direction along their axis. The SE band maximum is located at 7206 ± 0.4 cm-1. The energy and the power density of the superemission were estimated, along with the diffraction-limited divergence. At the pumping energy of 3 mJ/pulse, the SE energy measured by the detector was 0.74 mJ/pulse, corresponding to the total SE energy of 1.48 mJ/pulse, with the energy density of 18.5 mJ cm-2/pulse and the SE power density of 1.2 × 105 W cm-2/pulse. We report that a bundle of VA SWCNTs is an emitter with a relatively small divergence, not exceeding 3.9 × 10-3 rad. We developed a theoretical approach to explain such absorption and emission spectra. The developed theory is based on the earlier proposed SSH theory, which we extended to include the exchange interactions between the closest SWCNT neighbors. The developed theoretical ideas were implemented in a homemade FORTRAN code. This code was successfully used to calculate and reproduce the experimental spectra and to determine the SWCNT species that originate the respective absorption bands, with acceptable agreement between theory and experiment.

  9. Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films.

    Science.gov (United States)

    Holt, Ian; Gestmann, Ingo; Wright, Andrew C

    2013-10-01

    The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (>0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells.

  10. Fabrication of ultra thin and aligned carbon nanofibres from electrospun polyacrylonitrile nanofibres

    Indian Academy of Sciences (India)

    Javed Rafique; Jie Yu; Xiaoxiong Zha; Khalid Rafique

    2010-10-01

    Ultra thin and aligned carbon nanofibres (CNFs) have been fabricated by heat treatment from aligned polyacrylonitrile (PAN) nanofibre precursors prepared by electrospinning. The alignment of the precursor nanofibres was achieved by using a modified electrospinning set up developed recently, where a tip collector was used to collect and align the nanofibres. The average diameter of the aligned CNFs is about 80 nm. The stabilization and carbonization behaviour were studied mainly based on the randomly oriented PAN nanofibres. The effects of stabilization and carbonization temperatures, temperature-increasing rates, and with and without substrates on the morphology and structure of the CNFs were investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used to characterize the structure of the CNFs and thermogravimetric/differential temperature analysis was used to evaluate the thermal behaviour of PAN nanofibres.

  11. Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 马志斌; 王传新; 满卫东

    2005-01-01

    Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 ℃. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

  12. Electrospun polyamide 6/poly(allylamine hydrochloride) nanofibers functionalized with carbon nanotubes for electrochemical detection of dopamine.

    Science.gov (United States)

    Mercante, Luiza A; Pavinatto, Adriana; Iwaki, Leonardo E O; Scagion, Vanessa P; Zucolotto, Valtencir; Oliveira, Osvaldo N; Mattoso, Luiz H C; Correa, Daniel S

    2015-03-04

    The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 μmol L(-1), with detection limit of 0.15 μmol L(-1) (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors.

  13. Bicontinuous Structure of Li₃V₂(PO₄)₃ Clustered via Carbon Nanofiber as High-Performance Cathode Material of Li-Ion Batteries.

    Science.gov (United States)

    Chen, Lin; Yan, Bo; Xu, Jing; Wang, Chunguang; Chao, Yimin; Jiang, Xuefan; Yang, Gang

    2015-07-01

    In this work, the composite structure of Li3V2(PO4)3 (LVP) nanoparticles with carbon nanofibers (CNF) is designed. The size and location of LVP particles, and the degree of graphitization and diameter of carbon nanofibers, are optimized by electrospinning and heat treatment. The bicontinuous morphologies of LVP/CNF are dependent on the carbonization of PVP and simultaneous growing of LVP, with the fibers shrunk and the LVP crystals grown toward the outside. LVP nanocystals clustered via carbon nanofibers guarantee improving the diffusion ability of Li(+), and the carbon fiber simultaneously guarantees the effective electron conductivity. Compared with the simple carbon-coated LVP and pure LVP, the particle-clustered structure guarantees high rate capability and long-life cycling stability of NF-LVP as cathode for LIBs. At 20 C rate in the range 3.0-4.3 V, NF-LVP delivers the initial capacity of 122.6 mAh g(-1) close to the theoretical value of 133 mAh g(-1), and maintains 97% of the initial capacity at the 1000th cycle. The bead-like structure of cathode material clustered via carbon nanofibers via electrospinning will be further applied to high-performance LIBs.

  14. Load Transfer Analysis in Short Carbon Fibers with Radially-Aligned Carbon Nanotubes Embedded in a Polymer Matrix

    OpenAIRE

    2009-01-01

    A novel shortfiber composite in which the microscopic advanced fiber reinforcements are coated with radially aligned carbon nanotubes (CNTs) is analyzed in this study. A shear-lag model is developed to analyze the load transferred to such coated fibers from the aligned-CNT reinforced matrix in a hybrid composite application. It is found that if the carbon fibers are coated with radially aligned CNTs, then the axial load transferred to the fiber is reduced due to stiffening of the matrix by th...

  15. Stainless steel mesh supported nitrogen-doped carbon nanofibers for binder-free cathode in microbial fuel cells.

    Science.gov (United States)

    Chen, Shuiliang; Chen, Yu; He, Guanghua; He, Shuijian; Schröder, Uwe; Hou, Haoqing

    2012-04-15

    In this communication, we report a binder-free oxygen reduction cathode for microbial fuel cells. The binder-free cathode is prepared by growth of nitrogen-doped carbon nanofibers (NCNFs) on stainless steel mesh (SSM) via simple pyrolysis of pyridine. The interaction force between NCNFs and SSM surface is very strong which is able to tolerate water flush. The NCNFs/SSM cathode shows high and stable electrocatalytic activity for oxygen reduction reaction, which is comparable to that of Pt/SSM and ferricyanide cathode. This study proposes a promising low-cost binder-free cathode for microbial fuel cells.

  16. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2013-01-01

    Full Text Available To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g increased significantly than that of pure carbon nanotubes (6.7 F/g.

  17. Carbon nanofiber reinforced epoxy matrix composites and syntactic foams - mechanical, thermal, and electrical properties

    Science.gov (United States)

    Poveda, Ronald Leonel

    The tailorability of composite materials is crucial for use in a wide array of real-world applications, which range from heat-sensitive computer components to fuselage reinforcement on commercial aircraft. The mechanical, electrical, and thermal properties of composites are highly dependent on their material composition, method of fabrication, inclusion orientation, and constituent percentages. The focus of this work is to explore carbon nanofibers (CNFs) as potential nanoscale reinforcement for hollow particle filled polymer composites referred to as syntactic foams. In the present study, polymer composites with high weight fractions of CNFs, ranging from 1-10 wt.%, are used for quasi-static and high strain rate compression analysis, as well as for evaluation and characterization of thermal and electrical properties. It is shown that during compressive characterization of vapor grown carbon nanofiber (CNF)/epoxy composites in the strain rate range of 10-4-2800 s-1, a difference in the fiber failure mechanism is identified based on the strain rate. Results from compression analyses show that the addition of fractions of CNFs and glass microballoons varies the compressive strength and elastic modulus of epoxy composites by as much as 53.6% and 39.9%. The compressive strength and modulus of the syntactic foams is also shown to generally increase by a factor of 3.41 and 2.96, respectively, with increasing strain rate when quasi-static and high strain rate testing data are compared, proving strain rate sensitivity of these reinforced composites. Exposure to moisture over a 6 month period of time is found to reduce the quasi-static and high strain rate strength and modulus, with a maximum of 7% weight gain with select grades of CNF/syntactic foam. The degradation of glass microballoons due to dealkalization is found to be the primary mechanism for reduced mechanical properties, as well as moisture diffusion and weight gain. In terms of thermal analysis results, the

  18. Macroscopic Ensembles of Aligned Carbon Nanotubes in Bubble Imprints Studied by Polarized Raman Microscopy

    Directory of Open Access Journals (Sweden)

    Shota Ushiba

    2014-01-01

    Full Text Available We study the alignment of single-wall carbon nanotubes (SWCNTs in bubble imprints through polarized Raman microscopy. A hemispherical bubble containing SWCNTs is pressed against a glass substrate, resulting in an imprint of the bubble membrane with a coffee ring on the substrate. We find that macroscopic ensembles of aligned SWCNTs are obtained in the imprints, in which there are three patterns of orientations: (i azimuthal alignment on the coffee ring, (ii radial alignment at the edge of the membrane, and (iii random orientation at the center of the membrane. We also find that the alignment of SWCNTs in the imprints can be manipulated by spinning bubbles. The orientation of SWCNTs on the coffee ring is directed radially, which is orthogonal to the case of unspun bubbles. This approach enables one to align SWCNTs in large quantities and in a short time, potentially opening up a wide range of CNT-based electronic and optical applications.

  19. Effect of Wrapped Carbon Nanotubes on Optical Properties, Morphology, and Thermal Stability of Electrospun Poly(vinyl alcohol Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Naoual Diouri

    2013-01-01

    Full Text Available Electrospinning was used to elaborate poly(vinyl alcohol (PVA nanofibers in the presence of embedded multiwall carbon nanotubes (MWCNTs in surfactant and polymer. MWCNTs were dispersed in aqueous solution using both sodium dodecyl sulfate (SDS as surfactant and Poly(vinyl pyrrolidone (PVP. Changing the surfactant and polymer concentration reveals that the maximum dispersion achievable is corresponding to the mass ratios MWCNTs : SDS—1 : 5 and MWCNTs : SDS : PVP—1 : 5 : 0.6 in the presence of the PVP. After the optimization of the dispersion process, the SEM image of the PVA/PVP/SDS/MWCNTs electrospun fibers presents high stability of the fibers with diameter around 224 nm. Infrared spectroscopy and thermal gravimetric analysis elucidate the type of interaction between the PVA and the coated carbon nanotube. The presence of PVP wrapped carbon nanotubes reduced slightly the onset of the degradation temperature of the electrospun nanofibers.

  20. High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium

    Science.gov (United States)

    Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Abdullah, Aboubakr M.; Vinu, Ajayan; Iwai, Hideo; Al-Deyab, Salem S.

    2017-04-01

    Nitrogen-Doped Carbon Nanofiber (N-CNF)-supported NiO composite was prepared by electrospinning a sol-gel mixture of graphene and polyaniline (PANi) with aqueous solutions of Polyvinylpyrrolidone (PVP) followed by a high-temperature annealing process. The electrospun was stabilized for 2 h at 280 °C, carbonized for 5 h at 1200 °C then loaded by 10% NiO. The electrocatalytic activities of the produced nanocomposite have been studied using cyclic voltammetry, and chronoamperometry. Also, N-CNF was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and scanning-electron microscopy (SEM). The obtained N-doped carbon nanofiber was found to have a nitrogen content of 2.6 atomic% with a diameter range of (140-160) nm, and a surface area (393.3 m2 g-1). In addition, it showed a high electrocatalytic behavior towards methanol oxidation reaction in alkaline medium and high stability and resistivity to the adsorption of intermediates.

  1. Effects of Temperature and Catalyst Concentration on the Growth of Aligned Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaodong; LI Dan; WANG Ye; LIANG Ji

    2005-01-01

    The effects of preheating and pyrolysis temperatures and catalyst concentration on the synthesis of aligned carbon nanotubes (CNTs) using ferrocene as the catalyst and xylene as the carbon source in chemical vapor deposition were experimentally studied. The as-grown aligned CNTs were characterized by field emission scanning electron microscopy, transmission electronic microscopy, high-resolution transmission electronic microscopy, and Raman spectroscopy. The growth rate, the diameters, and the degree of crystal structure of the aligned CNTs were all found to depend on the preheating and pyrolysis temperatures and the catalyst concentration. The optimized conditions for the growth of aligned CNTs resulted in a rapid growth rate of 20.4 μm/min, with the CNTs having a good, uniform crystal structure, and clean surfaces with little amorphous carbon. The results also show that higher preheating temperatures and lower ferrocene concentrations favor the growth of single-walled CNTs.

  2. Electrocatalytic oxygen evolution reaction at a FeNi composite on a carbon nanofiber matrix in alkaline media

    Institute of Scientific and Technical Information of China (English)

    Xianghua An; Dongyoon Shin; Joey D. Ocon; Jae Kwang Lee; Young-il Son; Jaeyoung Lee

    2014-01-01

    Non-noble metals such as Fe and Ni have comparable electrocatalytic activity and stability to that of Ir and Ru in an oxygen evolution reaction (OER). In this study, we synthesized carbon nanofibers with embedded FeNi composites (FeNi-CNFs) as OER electrocatalysts by a facile route comprising electrospinning and the pyrolysis of a mixture of metal precursors and a polymer solution. FeNi-CNFs demonstrated catalytic activity and stability that were better than that of 20 wt%Ir on Vulcan carbon black in oxidizing water to produce oxygen in an alkaline media. Physicochemical and electrochemical characterization revealed that Fe and Ni had synergistic roles that enhanced OER activity by the uniform formation and widening of pores in the carbon structure, while the CNF matrix also contributed to the increased stability of the catalyst.

  3. Fabrication of carbon nanofiber-reinforced aluminum matrix composites assisted by aluminum coating formed on nanofiber surface by in situ chemical vapor deposition

    Science.gov (United States)

    Ogawa, Fumio; Masuda, Chitoshi

    2015-01-01

    The van der Waals agglomeration of carbon nanofibers (CNFs) and the weight difference and poor wettability between CNFs and aluminum hinder the fabrication of dense CNF-reinforced aluminum matrix composites with superior properties. In this study, to improve this situation, CNFs were coated with aluminum by a simple and low-cost in situ chemical vapor deposition (in situ CVD). Iodine was used to accelerate the transport of aluminum atoms. The coating layer formed by the in situ CVD was characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform-infrared spectroscopy, and x-ray photoelectron spectroscopy. The results confirmed that the CNFs were successfully coated with aluminum. The composites were fabricated to investigate the effect of the aluminum coating formed on the CNFs. The dispersion of CNFs, density, Vickers micro-hardness and thermal conductivity of the composites fabricated by powder metallurgy were improved. Pressure-less infiltration experiments were conducted to fabricate composites by casting. The results demonstrated that the wettability and infiltration were dramatically improved by the aluminum coating layer on CNFs. The aluminum coating formed by the in situ CVD technique was proved to be effective for the fabrication of CNF-reinforced aluminum matrix composites.

  4. Photocatalysis of sub-ppm limonene over multiwalled carbon nanotubes/titania composite nanofiber under visible-light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wan-Kuen, E-mail: wkjo@knu.ac.kr; Kang, Hyun-Jung

    2015-02-11

    Highlights: • A multiwalled carbon nanotube/titania composite nanofiber (MTCN) was synthesized. • Photocatalytic function of visible-activated MTCN was examined using tubular reactor. • MTCNs could be effectively used for the purification of sub-ppm gas-phase limonene. • The experimental results agreed well with Langmuir–Hinshelwood model. • Certain gas-phase intermediates were determined, but not for adsorbed intermediates. - Abstract: This study was conducted under visible-light exposure to investigate the photocatalytic characteristics of a multiwalled carbon nanotube/titania (TiO{sub 2}) composite nanofiber (MTCN) using a continuous-flow tubular reactor. The MTCN was prepared by a sol–gel process, followed by an electrospinning technique. The photocatalytic decomposition efficiency for limonene on the MTCN was higher than those obtained from reference TiO{sub 2} nanofibers or P25 TiO{sub 2}, and the experimental results agreed well with the Langmuir–Hinshelwood model. The CO concentrations generated during the photocatalysis did not reach levels toxic to humans. The mineralization efficiency for limonene on the MTCN was also higher than that for P25 TiO{sub 2}. Moreover, the mineralization efficiency obtained using the MTCN increased steeply from 8.3 to 91.1% as the residence time increased from 7.8 to 78.0 s, compared to the increase in the decomposition efficiencies for limonene from 90.1 to 99.9%. Three gas-phase intermediates (methacrolein, acetic acid, and limonene oxide) were quantitatively determined for the photocatalysis for limonene over the MTCN, whereas only two intermediates (acetic acid and limonene oxide) were quantitatively determined over P25 TiO{sub 2}. Other provisional gas-phase intermediates included cyclopropyl methyl ketone and 2-ethylbutanal.

  5. High-yield harvest of nanofibers/mesoporous carbon composite by pyrolysis of waste biomass and its application for high durability electrochemical energy storage.

    Science.gov (United States)

    Liu, Wu-Jun; Tian, Ke; He, Yan-Rong; Jiang, Hong; Yu, Han-Qing

    2014-12-02

    Disposal and recycling of the large scale biomass waste is of great concern. Themochemically converting the waste biomass to functional carbon nanomaterials and bio-oil is an environmentally friendly apporach by reducing greenhouse gas emissions and air pollution caused by open burning. In this work, we reported a scalable, "green" method for the synthesis of the nanofibers/mesoporous carbon composites through pyrolysis of the Fe(III)-preloaded biomass, which is controllable by adjustment of temperature and additive of catalyst. It is found that the coupled catalytic action of both Fe and Cl species is able to effectively catalyze the growth of the carbon nanofibers on the mesoporous carbon and form magnetic nanofibers/mesoporous carbon composites (M-NMCCs). The mechanism for the growth of the nanofibers is proposed as an in situ vapor deposition process, and confirmed by the XRD and SEM results. M-NMCCs can be directly used as electrode materials for electrochemical energy storage without further separation, and exhibit favorable energy storage performance with high EDLC capacitance, good retention capability, and excellent stability and durability (more than 98% capacitance retention after 10,000 cycles). Considering that biomass is a naturally abundant and renewable resource (over billions tons biomass produced every year globally) and pyrolysis is a proven technique, M-NMCCs can be easily produced at large scale and become a sustainable and reliable resource for clean energy storage.

  6. Electromagnetic Interference Behavior of Multiwall Carbon Nanotubes and Carbon Nanofibers Composites Under Fatigue

    Science.gov (United States)

    2012-03-01

    This led to the use of composite structures made of Kevlar /epoxy and graphite/epoxy. The U.S. military today are researching and testing...Laboratory. The first discovery of a carbon nano scaled molecule was in 1985 with fullerenes by Kroto, Smalley, and Curl at Rice University. A fullerene

  7. 75 FR 4528 - Certain Magnesia Carbon Bricks From the People's Republic of China: Alignment of Final...

    Science.gov (United States)

    2010-01-28

    ... International Trade Administration Certain Magnesia Carbon Bricks From the People's Republic of China: Alignment... Carbon Bricks (Bricks) from the People's Republic of China (PRC) with the final determinations of the antidumping duty (AD) investigations of Bricks from the PRC and Mexico. DATES: Effective Date: January...

  8. Risk analysis and protection measures in a carbon nanofiber manufacturing enterprise: an exploratory investigation.

    Science.gov (United States)

    Genaidy, Ash; Sequeira, Reynold; Rinder, Magda; A-Rehim, Amal

    2009-11-01

    The emerging US carbon nano-manufacturing sector accounts for 40% of nanotechnology product marketplace, thus, there is a significant potential for increased risks arising from workers' exposure to carbon nanofibers (CNF). This research aims at developing a low-cost/evidence-based tool, thereby, increasing the sustainability of CNF manufacturing firms. The following specific aims achieve the study objective: Aim 1 - To present a technical discussion of the proposed concept for risk analysis and protection measures; Aim 2 - To describe the manufacturing process utilized for the CNF production; Aim 3 - To describe the hazards typically encountered in a CNF manufacturing facility; and, Aim 4 - To document the application of the proposed tool for risk analysis and intervention strategy development. In this study, a four-step methodology was developed to protect worker health in the nano-manufacturing enterprise through the generation of improvement actions (i.e., suggested changes in the hazard/work environment characteristics and individual capabilities without specifying how changes are made) followed by interventions (i.e., workplace solutions which specify how changes are being implemented). The methodology was implemented in a CNF manufacturing enterprise in the Midwest of the US. The data collected were based on detailed observations and interviews with worker and management personnel. A detailed flow process analysis was conducted for the nano-manufacturing operation. Eleven hazards were identified at the facility. Analysis indicated that the computed risk scores ranged from moderate (i.e., requiring one to start with incremental changes, then, explore substantial changes, if needed) to very high (i.e., substantial changes should be planned in the short term, followed by incremental changes). A detailed intervention plan was presented for the identified hazards on the basis of criteria of applicability, cost, benefit and feasibility. Management personnel were in

  9. Growth and Characterization of Carbon Nanofibers on Fe/C-Fiber Textiles Coated by Deposition-Precipitation and Dip-Coating.

    Science.gov (United States)

    Lee, Sang-Won; Lee, Chang-Seop

    2015-09-01

    This research was conducted to synthesize carbon nanofibers on C-fiber textiles, by thermal chemical vapor deposition (CVD) using Fe catalyst. The substrate, which was a carbon textile consisting of non-woven carbon fibers and attached graphite particles, was oxidized by nitric acid, before the deposition process. Hydroxyl groups were created on the C-fiber textile, due to the oxidization step. Fe(III) hydroxide was subsequently deposited on the oxidized surface of the C-fiber textile. To deposit ferric particles, two different methods were tested: (i) deposition-precipitation, and (ii) dip-coating. For the experiments using both types of catalyst deposition, the weight ratio of Fe to C-fiber textile was also varied. Ferric particles were reduced to iron after deposition, by using H2/N2 gas, and carbon nanofibers (CNFs) were grown by flowing ethylene gas. Properties of carbon nanofibers created like this were analyzed through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), N2-sorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectoscopy (XPS), Thermal analysis (TG/DTA), and Raman spectroscopy. In the case of the deposition-precipitation method, the results show that the diameter of carbon nanofibers grew up to 40-60 nm and 30-55 nm, at which the weight ratios of Fe catalyst to C-fiber textiles were 1:30 and 1:70, respectively. When Fe particles were deposited by the dip-coating method, the diameter of carbon nanofibers grew up to 40-60 nm and 25-30 nm, for the ratios of Fe catalyst to C-fiber textiles of 1:10 and 1:30, respectively.

  10. Electrospun Pd nanoparticles loaded on Vulcan carbon/ conductive polymeric ionic liquid nanofibers for selective and sensitive determination of tramadol.

    Science.gov (United States)

    Fathirad, Fariba; Mostafavi, Ali; Afzali, Daryoush

    2016-10-12

    In the present work a sensitive and selective electrochemical sensor was fabricated based on a glassy carbon electrode which has been modified with Pd nanoparticles loaded on Vulcan carbon/conductive polymeric ionic liquid composite nanofibers. The nanostructures were characterized by UV-Vis, FT-IR, FESEM, EDX and XRD techniques. The electrochemical study of the modified electrode, as well as its efficiency for the electrooxidation of tramadol was described in 0.1 M phosphate buffered solution (PBS) (pH 7.0) using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and square wave voltammetry as diagnostic techniques. It has been found that application of the composite nanofibers result in a sensitivity enhancement and a considerable decrease in the anodic overpotential, leading to negative shifts about 200 mV in peak potential. The results exhibit a linear dynamic range from 0.05 μM to 200 μM and a detection limit of 0.015 μM for tramadol. Finally, the modified electrode was used for the determination of tramadol in pharmaceutical and biological samples.

  11. Oriented nanofibers embedded in a polymer matrix

    Science.gov (United States)

    Barrera, Enrique V. (Inventor); Rodriguez-Macias, Fernando J. (Inventor); Lozano, Karen (Inventor); Chibante, Luis Paulo Felipe (Inventor); Stewart, David Harris (Inventor)

    2011-01-01

    A method of forming a composite of embedded nanofibers in a polymer matrix is disclosed. The method includes incorporating nanofibers in a plastic matrix forming agglomerates, and uniformly distributing the nanofibers by exposing the agglomerates to hydrodynamic stresses. The hydrodynamic said stresses force the agglomerates to break apart. In combination or additionally elongational flow is used to achieve small diameters and alignment. A nanofiber reinforced polymer composite system is disclosed. The system includes a plurality of nanofibers that are embedded in polymer matrices in micron size fibers. A method for producing nanotube continuous fibers is disclosed. Nanofibers are fibrils with diameters of 100 nm, multiwall nanotubes, single wall nanotubes and their various functionalized and derivatized forms. The method includes mixing a nanofiber in a polymer; and inducing an orientation of the nanofibers that enables the nanofibers to be used to enhance mechanical, thermal and electrical properties. Orientation is induced by high shear mixing and elongational flow, singly or in combination. The polymer may be removed from said nanofibers, leaving micron size fibers of aligned nanofibers.

  12. Hollow core-shell structured silicon@carbon nanoparticles embed in carbon nanofibers as binder-free anodes for lithium-ion batteries

    Science.gov (United States)

    Chen, Yanli; Hu, Yi; Shen, Zhen; Chen, Renzhong; He, Xia; Zhang, Xiangwu; Li, Yongqiang; Wu, Keshi

    2017-02-01

    Silicon is regarded as one of the most promising candidates for lithium-ion battery anodes owing to its large theoretical energy density (about 4200 mAh g-1) and low working potential (vs. Li/Li+). However, its practical application is limited by structure degradation and a comparatively poor capacity retention caused by large volume changes during cycling. In this study, we have prepared a novel nanofiber form of silicon/carbon with hollow core-shell structured silicon@carbon (Si@C) nanoparticles embedded in carbon nanofibers. Voids between the silicon nanoparticle (SiNP) core and carbon shell help to accommodate the volume expansion associated with the lithiation/delithiation process in a working electrode and allow formation of a stable solid electrolyte interphase (SEI) film. The obtained electrodes exhibited good cycle performance with a high reversible capacity of 1020.7 mAh g-1 after 100 cycles at a current density of 0.2 A g-1, and also delivered excellent cycling performance at a high current density of 3.2 A g-1. The design of this new structure provides a potential method for developing other functional composite anode materials with high reversible capacities and long-term cycle stabilities.

  13. Re-grown aligned carbon nanotubes with improved field emission.

    Science.gov (United States)

    Lim, Xiaodai; Zhu, Yanwu; Varghese, Binni; Gao, Xingyu; Wee, Andrew Thye Shen; Sow, Chorng-Haur

    2012-01-01

    In this work, a simple technique to improve the field emission property of multi-walled carbon nanotubes is presented. Re-grown multi-walled carbon nanotubes are grown on the same substrates after the as-grown multi-walled carbon nanotubes are transferred to other substrates using polydimethylsiloxane as intermediation. For the duration of the synthesis of the re-grown multi-walled carbon nanotubes, similar synthesis parameters used in growing the as-grown multi-walled carbon nanotubes are utilized. As a form of possible application, field emission studies show -2.6 times improvement in field enhancement factor and more uniform emission for the re-grown multi-walled carbon nanotubes. In addition, the turn-on field is reduced from 2.85 V/microm to 1.40 V/microm. Such significant improvements are attributed to new emission sites comprising of sharp carbonaceous impurities encompassing both tip and upper portion of the multi-walled carbon nanotubes. As such, this technique presents a viable route for the production of multi-walled carbon nanotubes with better field emission quality.

  14. Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes into Dense, Aligned Rafts

    CERN Document Server

    Wu, Justin; Antaris, Alexander; Choi, Charina L; Xie, Liming; Wu, Yingpeng; Diao, Shuo; Chen, Changxin; Chen, Yongsheng; Dai, Hongjie

    2013-01-01

    Single-walled carbon nanotubes are promising nanoelectronic materials but face long-standing challenges including production of pure semiconducting SWNTs and integration into ordered structures. Here, highly pure semiconducting single-walled carbon nanotubes are separated from bulk materials and self-assembled into densely aligned rafts driven by depletion attraction forces. Microscopy and spectroscopy revealed a high degree of alignment and a high packing density of ~100 tubes/micron within SWNT rafts. Field-effect transistors made from aligned SWNT rafts afforded short channel (~150 nm long) devices comprised of tens of purely semiconducting SWNTs derived from chemical separation within a < 1 micron channel width, achieving unprecedented high on-currents (up to ~120 microamperes per device) with high on/off ratios. The average on-current was ~ 3-4 microamperes per tube. The results demonstrated densely aligned high quality semiconducting SWNTs for integration into high performance nanoelectronics.

  15. Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kong Yuxia; Yuan Jie [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Qiu Jun, E-mail: qiujun@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials of Education of Ministry, Shanghai 201804 (China)

    2012-07-01

    Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

  16. Self-fabrication of 3D Patterns on Aligned Carbon Nanotubes Films

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Because of its outstanding performance, an aligned nanotube film with micropatterns has been a research focus in the field of nano-science and technology. Although quite a number of researchers have been successful in constructing such patterns, the precondition for the success, until recently, is to obtain the patterned substrates in advance.A research group at the CAS Institute of Chemistry (ICCAS) has succeeded in self-assembly of threedimensional (3-D) micropatterns on aligned carbon nanotube films.

  17. Ferric oxide nanoparticles decorated carbon nanotubes and carbon nanofibers: From synthesis to enhanced removal of phenol

    Directory of Open Access Journals (Sweden)

    Hamza A. Asmaly

    2015-09-01

    Full Text Available In this work, ferric oxide nanoparticle decorated carbon fibers and carbon nanotubes (CNF/Fe2O3 and CNT/Fe2O3 were synthesized and characterized by scanning electron microscopy (SEM, thermogravimetric analysis (TGA, energy dispersive X-ray spectroscopy (EDS, transmission electron microscopy (TEM, X-ray diffraction (XRD, zeta potential and BET surface area analyzer. The prepared nanocomposites were evaluated or the removal of phenol ions from aqueous solution. The effects of experimental parameters, such as shaking speed, pH, contact time, adsorbent dosage and initial concentration, were evaluated for the phenol removal efficiency. The adsorption experimental data were represented by both the Langmuir and Freundlich isotherm models. The Langmuir isotherm model best fitted the data on the adsorption of phenol, with a high correlation coefficient. The adsorption capacities, as determined by the Langmuir isotherm model were 0.842, 1.098, 1.684 and 2.778 mg/g for raw CNFs, raw CNTs, CNF–Fe2O3 and CNT–Fe2O3, respectively.

  18. Highly flexible NiCo2O4/CNTs doped carbon nanofibers for CO2 adsorption and supercapacitor electrodes.

    Science.gov (United States)

    Iqbal, Nousheen; Wang, Xianfeng; Ahmed Babar, Aijaz; Yu, Jianyong; Ding, Bin

    2016-08-15

    Controllable synthesis of carbon nanofibers (CNFs) with hierarchical porosity and high flexibility are extremely desirable for CO2 adsorption and energy storage applications. Herein, we report a nickel cobaltite/carbon nanotubes doped CNFs (NiCo2O4/CNTs CNFs) mesoporous membrane that shows well-developed flexibility, tailored pore structure, hydrophobic character, and high stability. Ascribed to these unique features, NiCo2O4/CNTs CNFs membrane shows high CO2 capture of 1.54mmol/g at 25°C and 1.0bar, and electrochemical measurements for supercapacitors exhibit good performance with specific capacitances of 220F/g (in 1M KOH) at a current density of 1A/g. The successful synthesis of such hybrid membrane provides new insight into development of various multifunctional applications.

  19. Hybrid magnetic amphiphilic composites based on carbon nanotube/nanofibers and layered silicates fragments as efficient adsorbent for ethynilestradiol.

    Science.gov (United States)

    Purceno, Aluir D; Teixeira, Ana Paula C; de Souza, Nubia Janaína; Fernandez-Outon, Luis E; Ardisson, José D; Lago, Rochel M

    2012-08-01

    In this work, hybrid magnetic amphiphilic composites were prepared by the catalytic growth of carbon nanotubes (CNTs) and nanofibers CNF on layered silicates fragments. SEM, TEM, Raman, XRD, Mössbauer, TG/DTA showed that CVD with CH(4) at 800°C produced CNF and magnetic Fe cores fixed on the surface of microfragments of silicates layers. Due to the amphiphilic character, the composites can be easily dispersed in water and efficiently adsorb hydrophobic contaminant molecules. For example, the composites showed remarkable adsorption capacities for the hormone ethinylestradiol, e.g. 2-4 mg m(-2), compared to ca. 0.1 mg m(-2) obtained for high surface area activated carbon and multiwall CNT. These results are discussed in terms of a high hydrophobic exposed surface area of the CNT and CNF fixed on the layered silicates fragments surface. Moreover, the composites can be easily removed from water by a simple magnetic separation process.

  20. Preparation of polyacrylnitrile (PAN)/ Manganese oxide based activated carbon nanofibers (ACNFs) for adsorption of Cadmium (II) from aqueous solution

    Science.gov (United States)

    Abdullah, N.; Yusof, N.; Jaafar, J.; Ismail, AF; Che Othman, F. E.; Hasbullah, H.; Salleh, W. N. W.; Misdan, N.

    2016-06-01

    In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) were prepared via electrospinning process. The electrospun PAN/MnO2-based ACNFs were characterised in term of its morphological structure and specific surface area using SEM and BET analysis respectively. The comparative adsorption study of cadmium (II) ions from aqueous solution between the neat ACNFs, composite ACNFs and commercial granular activated carbon was also conducted. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads with smaller fiber diameter of 437.2 nm as compared to the neat ACNFs which is 575.5 nm. BET analysis elucidated specific surface area of ACNFs/MnO2 to be 67 m2/g. Under adsorption study, it was found out that Cd (II) removal by ACNFs/MnO2 was the highest (97%) followed by neat ACNFs (96%) and GAC (74%).

  1. Evaluating the mechanistic evidence and key data gaps in assessing the potential carcinogenicity of carbon nanotubes and nanofibers in humans

    DEFF Research Database (Denmark)

    Kuempel, Eileen D.; Jaurand, Marie-Claude; Møller, Peter

    2017-01-01

    In an evaluation of carbon nanotubes (CNTs) for the IARC Monograph 111, the Mechanisms Subgroup was tasked with assessing the strength of evidence on the potential carcinogenicity of CNTs in humans. The mechanistic evidence was considered to be not strong enough to alter the evaluations based...... on the animal data. In this paper, we provide an extended, in-depth examination of the in vivo and in vitro experimental studies according to current hypotheses on the carcinogenicity of inhaled particles and fibers. We cite additional studies of CNTs that were not available at the time of the IARC meeting...... in October 2014, and extend our evaluation to include carbon nanofibers (CNFs). Finally, we identify key data gaps and suggest research needs to reduce uncertainty. The focus of this review is on the cancer risk to workers exposed to airborne CNT or CNF during the production and use of these materials...

  2. Electrospun highly ordered mesoporous silica-carbon composite nanofibers for rapid extraction and prefractionation of endogenous peptides.

    Science.gov (United States)

    Zhu, Gang-Tian; Chen, Xi; He, Xiao-Mei; Wang, Han; Zhang, Zheng; Feng, Yu-Qi

    2015-03-09

    A simple method was developed for the preparation of ordered mesoporous silica-carbon composite nanofibers (OMSCFs). The OMSCFs exhibited high carbon content, continuously long fibrous properties, uniform accessible mesopores, and a large surface area. The OMSCFs were also found to have ion-exchange capacity. On the basis of the size-exclusion effect of the mesopores and mixed-mode hydrophobic/ion-exchange interactions, the OMSCFs were applied for rapid enrichment of endogenous peptides by using a miniaturized solid-phase extraction format. The adsorption mechanism was studied, and the eluting solution was optimized with standard peptide/protein solutions and protein digests. Employing a successive three-step elution strategy, followed by LC-MS/MS analysis, led to excellent performance with this approach in the extraction and prefractionation of peptides from human serum.

  3. Synthesis and characterization of well-aligned carbon nitrogen nanotubes by microwave plasma chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Well-aligned carbon nitrogen nanotube films have been synthesized successfully on mesoporous silica substrates by microwave plasma chemical vapor deposition (MWPCVD) method. Studies on their morphology, structure, and composition by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX), respectively, indicate that these nanotubes consist of linearly polymerized carbon nitrogen nanobells, and the nitrogen atoms have been doped into carbon netweork to form a new structure C1-xNx (x=0.16±0.01). X-ray photoelectron spectroscopy (XPS) results of the samples further demonstrate that carbon bonds covalently with nitrogen in all the carbon nitrogen nanotube films.

  4. Effect of Particle Density on the Aligned Growth of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Sheng-gao; WANG Jian-hua; HAN Jian-jun

    2004-01-01

    Aligned carbon nanotubes (CNTs) were prepared on Ni-coated Ni substrate by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at temperature of 550℃.The experimental results show a direct correlation between the alignment of CNTs and the density of the catalyst particles at low temperature.When the particle density is high enough,among CNTs there are strong interactions that can inhibit CNTs from growing randomly.The crowding effect among dense CNTs results in the aligned growth of CNTs at low temperature.

  5. Influence of filler alignment in the mechanical and electrical properties of carbon nanotubes/epoxy nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Felisberto, M. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Arias-Duran, A. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Ramos, J.A.; Mondragon, I. [Dep. Ingenieria Quimica y M. Ambiente. Esc. Politecnica. UPV/EHU, Pza. Europa 1, Donostia-San Sebastian 20018 (Spain); Candal, R. [INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Escuela de Ciencia y Tecnologia-UNSAM, San Martin, Prov. De Buenos Aires (Argentina); Goyanes, S. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Rubiolo, G.H., E-mail: rubiolo@cnea.gov.ar [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Dep. Materiales, Comision Nacional de Energia Atomica (CNEA-CAC), Avda Gral Paz 1499, B1650KNA San Martin (Argentina)

    2012-08-15

    In this work, we report the mechanical and electrical properties of carbon nanotubes/epoxy composites prepared with aligned and randomly oriented nanotubes as filler. The samples are disks of 30 mm in diameter and 3 mm in thickness. To obtain the carbon nanotubes alignment, an external electric field (250 VAC; 50 Hz) was applied through the thickness of the sample during all the cure process. The AC electrical current was measured, during the cure, as a strategy to determine the optimum time in which the alignment reaches the maximum value. DC conductivity measured after the cure shows a percolation threshold in the filler content one order of magnitude smaller for composites with aligned nanotubes than for composites with randomly oriented filler (from 0.06 to 0.5 wt%). In the percolation threshold, the achieved conductivity was 1.4 Multiplication-Sign 10{sup -5} Sm{sup -1}. In both cases, aligned and randomly distributed carbon nanotube composites, the wear resistance increases with the addition of the filler while the Rockwell hardness decreases independently of the nanotubes alignment.

  6. Aligned carbon nanotubes physics, concepts, fabrication and devices

    CERN Document Server

    Ren, Zhifeng; Wang, Yang

    2012-01-01

    This book surveys the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. The text illustrates major fabrication methods in detail, particularly the most widely used PECVD growth techniques.

  7. Vertically aligned multiwalled carbon nanotubes as electronic interconnects.

    OpenAIRE

    Gopee, Vimal C.

    2017-01-01

    The drive for miniaturisation of electronic circuits provides new materials challenges for the electronics industry. Indeed, the continued downscaling of transistor dimensions, described by Moore’s Law, has led to a race to find suitable replacements for current interconnect materials to replace copper. Carbon nanotubes have been studied as a suitable replacement for copper due to its superior electrical, thermal and mechanical properties. One of the advantages of using carbon nanotubes is th...

  8. Carbon and Binder-Free Air Electrodes Composed of Co3O 4 Nanofibers for Li-Air Batteries with Enhanced Cyclic Performance.

    Science.gov (United States)

    Lee, Chan Kyu; Park, Yong Joon

    2015-12-01

    In this study, to fabricate a carbon free (C-free) air electrode, Co3O4 nanofibers were grown directly on a Ni mesh to obtain Co3O4 with a high surface area and good contact with the current collector (the Ni mesh). In Li-air cells, any C present in the air electrode promotes unwanted side reactions. Therefore, the air electrode composed of only Co3O4 nanofibers (i.e., C-free) was expected to suppress these side reactions, such as the decomposition of the electrolyte and formation of Li2CO3, which would in turn enhance the cyclic performance of the cell. As predicted, the Co3O4-nanofiber electrode successfully reduced the accumulation of reaction products during cycling, which was achieved through the suppression of unwanted side reactions. In addition, the cyclic performance of the Li-air cell was superior to that of a standard electrode composed of carbonaceous material.

  9. Imaging, Spectroscopic, Mechanical and Biocompatibility Studies of Electrospun Tecoflex(®) EG 80A Nanofibers and Composites Thereof Containing Multiwalled Carbon Nanotubes.

    Science.gov (United States)

    Macossay, Javier; Sheikh, Faheem A; Cantu, Travis; Eubanks, Thomas M; Salinas, M Esther; Farhangi, Chakavak S; Ahmad, Hassan; Hassan, M Shamshi; Khil, Myung-Seob; Maffi, Shivani K; Kim, Hern; Bowlin, Gary L

    2014-12-01

    The present study discusses the design, development and characterization of electrospun Tecoflex(®) EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C-N and N-H bonds in polyurethanes are responsible for the interactions with MWCNTs. Furthermore, tensile testing indicated an increase in the Young's modulus of the nanofibers as the MWCNTs concentration was increased. Finally, NIH 3T3 fibroblasts were seeded on the obtained nanofibers, demonstrating cell biocompatibility and proliferation. Therefore, the results indicate the successful formation of polyurethane nanofibers with enhanced mechanical properties, and demonstrate their biocompatibility, suggesting their potential application in biomedical areas.

  10. Imaging, Spectroscopic, Mechanical and Biocompatibility Studies of Electrospun Tecoflex® EG 80A Nanofibers and Composites Thereof Containing Multiwalled Carbon Nanotubes

    Science.gov (United States)

    Macossay, Javier; Sheikh, Faheem A.; Cantu, Travis; Eubanks, Thomas M.; Salinas, M. Esther; Farhangi, Chakavak S.; Ahmad, Hassan; Hassan, M. Shamshi; Khil, Myung-seob; Maffi, Shivani K.; Kim, Hern; Bowlin, Gary l.

    2014-01-01

    The present study discusses the design, development and characterization of electrospun Tecoflex® EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C-N and N-H bonds in polyurethanes are responsible for the interactions with MWCNTs. Furthermore, tensile testing indicated an increase in the Young’s modulus of the nanofibers as the MWCNTs concentration was increased. Finally, NIH 3T3 fibroblasts were seeded on the obtained nanofibers, demonstrating cell biocompatibility and proliferation. Therefore, the results indicate the successful formation of polyurethane nanofibers with enhanced mechanical properties, and demonstrate their biocompatibility, suggesting their potential application in biomedical areas. PMID:25435600

  11. Preparation and characterization of aligned carbon nanotubes coated with titania nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YU Hongtao; ZHAO Huimin; QUAN Xie; CHEN Shuo

    2006-01-01

    Well-aligned carbon nanotubes coated with titania (TiO2) were prepared by atmospheric pressure chemical vapor deposition (APCVD), and the sequential experiments including carbon nanotubes preparation, air-oxidation purification and titania nanoparticles coating were performed at different temperatures in the same reactor. Scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction patterns (XRD), and energy- dispersive X-ray spectra (EDX) demonstrated the well-aligned nanotubes and TiO2 nanoparticles in close proximity and the average diameter of TiO2 nanoparticles was 11.5 nm.

  12. Metal-Support Interactions of Platinum Nanoparticles Decorated N-Doped Carbon Nanofibers for the Oxygen Reduction Reaction.

    Science.gov (United States)

    Melke, Julia; Peter, Benedikt; Habereder, Anja; Ziegler, Juergen; Fasel, Claudia; Nefedov, Alexei; Sezen, Hikmet; Wöll, Christof; Ehrenberg, Helmut; Roth, Christina

    2016-01-13

    N-doped carbon materials are discussed as catalyst supports for the electrochemical oxygen reduction reaction (ORR) in fuel cells. This work deals with the preparation of Pt nanoparticles (NPs) supported on N-doped carbon nanofibers (N-CNF) from a polyaniline nanofiber (PANI NF) precursor, and investigates the ORR activity of the produced materials. Initially, Pt NPs are deposited on PANI NFs. The PANI NF precursors are characterized by near-edge X-ray absorption fine structure (NEXAFS) and transmission electron microscopy (TEM) measurements. It is shown, that in the PANI NF precursor materials electrons from the Pt are being transferred toward the π-conjugated systems of the aromatic ring. This strong interaction of Pt atoms with PANI explains the high dispersion of Pt NPs on the PANI NF. Subsequently, the PANI NF precursors are carbonized at different heat-treatment conditions resulting in structurally different N-CNFs which are characterized by NEXAFS, X-ray photoelectron spectroscopy (XPS) ,and TEM measurements. It is shown that an interaction between N-groups and Pt NPs exists in all investigated N-CNFs. However, the N-CNFs differ in the composition of the N-species and the dispersion of the Pt NPs. A small mean Pt NP size with a narrow size distribution is attributed to the presence of pyrdinic N-groups in the N-CNFs, whereas, for the N-CNFs with mainly graphitic and pyrrolic N-groups, an increase in the average Pt NP size with a broad size distribution is found. The ORR activity in alkaline media investigated by Koutecky-Levich analysis of rotating disk electrode measurements showed a largely enhanced ORR activity in comparison to a conventional Pt/C catalyst.

  13. Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition.

    Science.gov (United States)

    D'Arcy, Julio M; Tran, Henry D; Stieg, Adam Z; Gimzewski, James K; Kaner, Richard B

    2012-05-21

    A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.

  14. Pulse gas alignment and AFM manipulation of single-wall carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    TIAN XiaoJun; WANG YueChao; XI Ning; DONG ZaiLi; TUNG Steve

    2008-01-01

    In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube (SWCNT), oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be solved. Pulse gas alignment with substrate downward tilt is proposed to realize the controllable alignment of SWCNTs. Experimental results demonstrate that 84% SWCNTs are aligned in -15°- 15° angular to the pulse gas direction. A modified nanomanipulation technology based on atomic force microscope (AFM) is utilized to perform various kinds of SWCNT manipulation, such as SWCNT separation from the "Y" CNT, catalyst removal from the SWCNT end, continual nano buckles fabrication on SWCNT and even stretching to break, which provides a feasible way to modify the size, shape and the electrical property of SWCNTs.

  15. Synthesis, characterization and functionalization of vertically aligned carbon nanotube arrays

    OpenAIRE

    2012-01-01

    Ankara : The Materials Science and Nanotechnology Program of the Graduate School of Engineering and Sciences of Bilkent University, 2012. Thesis (Ph. D.) -- Bilkent University, 2012. Includes bibliographical refences. In the last decade, there has been an increased interest on carbon nanotubes (CNTs) for various applications due to their unique structural, electronic, mechanical and chemical properties. Synthesis of CNTs is no more a challenge with the enhancements and diver...

  16. Vertically aligned carbon nanotubes as anode and air-cathode in single chamber microbial fuel cells

    Science.gov (United States)

    Amade, R.; Moreno, H. A.; Hussain, S.; Vila-Costa, M.; Bertran, E.

    2016-10-01

    Electrode optimization in microbial fuel cells is a key issue to improve the power output and cell performance. Vertically aligned carbon nanotubes (VACNTs) grown on low cost stainless-steel mesh present an attractive approach to increase the cell performance while avoiding the use of expensive Pt-based materials. In comparison with non-aligned carbon nanotubes (NACNTs), VACNTs increase the oxygen reduction reaction taking place at the cathode by a factor of two. In addition, vertical alignment also increases the power density up to 2.5 times with respect to NACNTs. VACNTs grown at the anode can further improve the cell performance by increasing the electrode surface area and thus the electron transfer between bacteria and the electrode. The maximum power density obtained using VACNTs was 14 mW/m2 and 160 mV output voltage.

  17. Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films.

    Science.gov (United States)

    Won, Yoonjin; Gao, Yuan; Panzer, Matthew A; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W; Cai, Wei; Goodson, Kenneth E

    2013-12-17

    Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies--from thermal solar to automotive waste heat recovery systems--whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties.

  18. A Review on Nanomaterial Dispersion, Microstructure, and Mechanical Properties of Carbon Nanotube and Nanofiber Reinforced Cementitious Composites

    Directory of Open Access Journals (Sweden)

    Shama Parveen

    2013-01-01

    Full Text Available Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs and nanofibers (CNFs have motivated the development of advanced nanocomposites with outstanding and multifunctional properties. After achieving a considerable success in utilizing these unique materials in various polymeric matrices, recently tremendous interest is also being noticed on developing CNT and CNF reinforced cement-based composites. However, the problems related to nanomaterial dispersion also exist in case of cementitious composites, impairing successful transfer of nanomaterials' properties into the composites. Performance of cementitious composites also depends on their microstructure which is again strongly influenced by the presence of nanomaterials. In this context, the present paper reports a critical review of recent literature on the various strategies for dispersing CNTs and CNFs within cementitious matrices and the microstructure and mechanical properties of resulting nanocomposites.

  19. Using Converter Dust to Produce Low Cost Cementitious Composites by in situ Carbon Nanotube and Nanofiber Synthesis

    Directory of Open Access Journals (Sweden)

    Péter Ludvig

    2011-03-01

    Full Text Available Carbon nanotubes (CNTs and nanofibers (CNFs were synthesized on clinker and silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an in situ chemical vapor deposition (CVD process using converter dust, an industrial byproduct, as iron precursor. The use of these materials reduces the cost, with the objective of application in large-scale nanostructured cement production. The resulting products were analyzed by scanning electron microscopy (SEM, transmission electron microscopy (TEM and thermogravimetric analysis (TGA and were found to be polydisperse in size and to have defective microstructure. Some enhancement in the mechanical behavior of cement mortars was observed due to the addition of these nano-size materials. The contribution of these CNTs/CNFs to the mechanical strength of mortar specimens is similar to that of high quality CNTs incorporated in mortars by physical mixture.

  20. Direct electrochemistry and electrocatalysis of heme-proteins immobilized in porous carbon nanofiber/room-temperature ionic liquid composite film

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Qinglin [Institute of Analytical Science/Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, Northwest University, Xi' an, Shaanxi 710069 (China); Zheng Jianbin, E-mail: zhengjb@nwu.edu.c [Institute of Analytical Science/Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, Northwest University, Xi' an, Shaanxi 710069 (China); Shangguan Xiaodong [Institute of Analytical Science/Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, Northwest University, Xi' an, Shaanxi 710069 (China); Lin Wanghua; Li Yuanyao [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan (China); Liu Ruixiao [Institute of Analytical Science/Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, Northwest University, Xi' an, Shaanxi 710069 (China)

    2010-03-30

    The combination of porous carbon nanofiber (PCNF) and room-temperature ionic liquid (RTIL) provided a suitable microenvironment for heme-proteins to transfer electron directly. Hemoglobin, myoglobin, and cytochrome c incorporated in PCNF/RTIL films exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks at about -0.28 V vs. SCE in pH 7.0 buffers, respectively, characteristic of the protein heme Fe(III)/Fe(II) redox couples. The cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the modified electrode. The heme/PCNF/RTIL/CHIT films were also characterized by UV-vis spectroscopy, indicating that heme-proteins in the composite film could retain its native structure. Oxygen, hydrogen peroxide, and nitrite were catalytically reduced at the heme/PCNF/RTIL/CHIT film modified electrodes, showing the potential applicability of the films as the new type of biosensors or bioreactors based on direct electrochemistry of the redox proteins.

  1. Electrospinning of polyvinylidene difluoride with carbon nanotubes: synergistic effects of extensional force and interfacial interaction on crystalline structures.

    Science.gov (United States)

    Huang, Shu; Yee, Wu Aik; Tjiu, Wuiwui Chauhari; Liu, Ye; Kotaki, Masaya; Boey, Yin Chiang Freddy; Ma, Jan; Liu, Tianxi; Lu, Xuehong

    2008-12-02

    Polyvinylidene difluoride (PVDF) solutions containing a very low concentration of single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) of similar surface chemistry, respectively, were electrospun, and the nanofibers formed were collected using a modified rotating disk collector. The polymorphic behavior and crystal orientation of the nanofibers were studied using wide-angle X-ray diffraction and infrared spectroscopy, while the nanotube alignment and interfacial interactions in the nanofibers were probed by transmission electron microscopy and Raman spectroscopy. It is shown that the interfacial interaction between the SWCNTs and PVDF and the extensional force experienced by the nanofibers in the electrospinning and collection processes can work synergistically to induce highly oriented beta-form crystallites extensively. In contrast, the MWCNTs could not be well aligned along the nanofiber axis, which leads to a lower degree of crystal orientation.

  2. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide

    Science.gov (United States)

    Leyva-Porras, César; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.; Avila-Vega, Yazmín I.; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  3. Characteristics and Electrochemical Performance of Si-Carbon Nanofibers Composite as Anode Material for Binder-Free Lithium Secondary Batteries.

    Science.gov (United States)

    Hyun, Yura; Park, Heai-Ku; Park, Ho-Seon; Lee, Chang-Seop

    2015-11-01

    The carbon nanofibers (CNFs) and Si-CNFs composite were synthesized using a chemical vapor deposition (CVD) method with an iron-copper catalyst and silicon-covered Ni foam. Acetylene as a carbon source was flowed into the quartz reactor of a tubular furnace heated to 600 degrees C. This temperature was maintained for 10 min to synthesize the CNFs. The morphologies, compositions, and crystal quality of the prepared CNFs were characterized by Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the Si-CNFs composite as an anode of the Li secondary batteries were investigated using a three-electrode cell. The as-deposited Si-CNF composite on the Ni foam was directly employed as an working electrode without any binder, and lithium foil was used as the counter and reference electrode. A glass fiber separator was used as the separator membrane. Two kinds of electrolytes were employed; 1) 1 M LiPF6 was dissolved in a mixture of EC (ethylene carbonate): PC (propylene carbonate): EMC (Ethyl methyl carbonate) in a 1:1:1 volume ratio and 2) 1 M LiClO4 was dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge-discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. The resulting Si-CNFs composite achieved the large discharge capacity of 613 mAh/g and much improved cycle-ability with the retention rate of 87% after 20 cycles.

  4. Synergistic effect of carbon nanofiber/nanotube composite catalyst on carbon felt electrode for high-performance all-vanadium redox flow battery.

    Science.gov (United States)

    Park, Minjoon; Jung, Yang-jae; Kim, Jungyun; Lee, Ho il; Cho, Jeaphil

    2013-10-01

    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 V(2+)/V(3+) and VO(2+)/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.

  5. Vertically aligned carbon nanotubes for sensing unidirectional fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Kiani, Keivan, E-mail: k_kiani@kntu.ac.ir

    2015-05-15

    From applied mechanics points of view, potential application of ensembles of single-walled carbon nanotubes (SWCNTs) as fluid flow sensors is aimed to be examined. To this end, useful nonlocal analytical and numerical models are developed. The deflection of the ensemble of SWCNTs at the tip is introduced as a measure of its sensitivity. The influences of the length and radius of the SWCNT, intertube distance, fluid flow velocity, and distance of the ensemble from the leading edge of the rigid base on the deflection field of the ensemble are comprehensively examined. The obtained results display how calibration of an ensemble of SWCNTs can be methodically carried out in accordance with the characteristics of the ensemble and the external fluid flow.

  6. Polyvinyl Alcohol-derived carbon nanofibers/carbon nanotubes/sulfur electrode with honeycomb-like hierarchical porous structure for the stable-capacity lithium/sulfur batteries

    Science.gov (United States)

    Deng, Nanping; Kang, Weimin; Ju, Jingge; Fan, Lanlan; Zhuang, Xupin; Ma, Xiaomin; He, Hongsheng; Zhao, Yixia; Cheng, Bowen

    2017-04-01

    The honeycomb-like hierarchical porous carbon nanofibers (PCNFs)-carbon nanotubes (CNTs)-sulfur(S) composite electrode is successfully desgined and prepared through ball-milling and heating method, in which the PCNFs are carbonized from fibers in the membrane composed of Polyvinyl Alcohol and Polytetrafluoroethylene by electro-blown spinning technology. The prepared PCNFs-CNTs-S composite are regarded as cathode for lithium-sulfur battery. The tailored porous structure and CNTs in the composite facilitate construction of a high electrical conductive pathway and store more S/polysulfides, and the dissoluble loss of intermediate S species in electrolyte can also be restrained because of acidized PVA-based porous carbon nanofibers. Meanwhile, the porous strcucture and CNTs can effectively alleviate volume changes in battery cycling process. Moreover, the presence of LiNO3 in electrolyte helps the electrochemical oxidation of Li2S and LiNO3-derived surface film effectively suppresses the migration of soluble polysulfide to the Li anode surface. Therefore, the obtained PCNFs-CNTs-S cathode exhibits excellent performance in Li-S battery with a high initial discharge capacity as high as 1302.9 mAh g-1, and super stable capacity retention with 809.1 mAh g-1 after 300 cycles at the current density of 837.5 mA g-1 (0.5 C). And the rate capability of PCNFs-CNTs-S electrode is much better than those of CNTs-S and PCNFs-S electrodes.

  7. Alignment of carbon nanotubes on pre-structured silicon by surface acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, Klaus M; Ebbecke, Jens; Wixforth, Achim [Institut fuer Physik der Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany)

    2006-09-14

    Carbon nanotubes have been deposited and aligned onto the pre-structured metal contacts of a silicon chip. Crucial for the deposition and alignment process are micro-fluidic flow fields combined with electric dipole fields generated by surface acoustic waves within a gap filled with an aqueous carbon nanotube suspension. This gap is formed when the pre-structured silicon chip is flipped onto the piezoelectric lithium niobate substrate, allowing for the generation of surface acoustic waves. The contacting probability of carbon nanotubes on the prestructured metal contacts has been found to be 37%. In combination with back-gates, these structures define three-terminal devices and the first current-voltage characteristics.

  8. Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

    Science.gov (United States)

    Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

    2015-11-01

    We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

  9. The precise self-assembly of individual carbon nanotubes using magnetic capturing and fluidic alignment

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Joon S; Rust, Michael J; Do, Jaephil; Ahn, Chong H [Department of Electrical and Computer Engineering, Microsystems and BioMEMS Laboratory, University of Cincinnati, Cincinnati, OH 45221 (United States); Yun, Yeo-Heung; Schulz, Mark J [Department of Mechanical Engineering, University of Cincinnati, 45221 (United States); Shanov, Vesselin, E-mail: chong.ahn@uc.ed [Department of Chemical and Materials Engineering, University of Cincinnati, 45221 (United States)

    2009-08-12

    A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nanobiosensors.

  10. Optimal Synthesis of Horizontally Aligned Single-Walled Carbon Nanotubes and Their Biofunctionalization for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Dawoon Jung

    2016-01-01

    Full Text Available As an influential candidate for highly sensitive biomolecule sensor, which can capture disease related biomolecules, carbon nanotube is useful material due to its unique properties. To adopt as a sensing platform, it is strongly needed to find optimal refined synthetic condition. In order to find the optimal synthetic conditions of horizontally aligned CNT, we performed quantity control of the mixed gases of H2 and CH4 injected. We successfully find that the formation of amorphous-like carbon was critically affected by some gas condition such as the flow rate of injected gases and ratios of gas mixture. Moreover, it should be noted that our horizontally aligned carbon nanotube array platform developed would offer another potential in developing nanoscale light source, where light emission results from electron-hole carrier recombination.

  11. Alignment of Carbon Nanotubes in Carbon Nanotube Fibers Through Nanoparticles: A Route for Controlling Mechanical and Electrical Properties.

    Science.gov (United States)

    Hossain, Muhammad Mohsin; Islam, Md Akherul; Shima, Hossain; Hasan, Mudassir; Lee, Moonyong

    2017-02-15

    This is the first study that describes how semiconducting ZnO can act as an alignment agent in carbon nanotubes (CNTs) fibers. Because of the alignment of CNTs through the ZnO nanoparticles linking groups, the CNTs inside the fibers were equally distributed by the attraction of bonding forces into sheetlike bunches, such that any applied mechanical breaking load was equally distributed to each CNT inside the fiber, making them mechanically robust against breaking loads. Although semiconductive ZnO nanoparticles were used here, the electrical conductivity of the aligned CNT fiber was comparable to bare CNT fibers, suggesting that the total electron movement through the CNTs inside the aligned CNT fiber is not disrupted by the insulating behavior of ZnO nanoparticles. A high degree of control over the electrical conductivity was also demonstrated by the ZnO nanoparticles, working as electron movement bridges between CNTs in the longitudinal and crosswise directions. Well-organized surface interface chemistry was also observed, which supports the notion of CNT alignment inside the fibers. This research represents a new area of surface interface chemistry for interfacially linked CNTs and ZnO nanomaterials with improved mechanical properties and electrical conductivity within aligned CNT fibers.

  12. Aligned, ultralong single-walled carbon nanotubes: from synthesis, sorting, to electronic devices.

    Science.gov (United States)

    Liu, Zhongfan; Jiao, Liying; Yao, Yagang; Xian, Xiaojun; Zhang, Jin

    2010-06-04

    Aligned, ultralong single-walled carbon nanotubes (SWNTs) represent attractive building blocks for nanoelectronics. The structural uniformity along their tube axis and well-ordered two-dimensional architectures on wafer surfaces may provide a straightforward platform for fabricating high-performance SWNT-based integrated circuits. On the way towards future nanoelectronic devices, many challenges for such a specific system also exist. This Review summarizes the recent advances in the synthesis, identification and sorting, transfer printing and manipulation, device fabrication and integration of aligned, ultralong SWNTs in detail together with discussion on their major challenges and opportunities for their practical application.

  13. Effects of potassium on Ni-K/Al2O3 catalysts in the synthesis of carbon nanofibers by catalytic hydrogenation of CO2.

    Science.gov (United States)

    Chen, Ching S; Lin, Jarrn H; You, Jiann H; Yang, Kuo H

    2010-03-25

    Commercially available Ni/Al(2)O(3) samples containing various concentrations of potassium were used to achieve carbon deposition from CO(2) via catalytic hydrogenation. Experimental results show that K additives can induce the formation of carbon nanofibers or carbon deposition on Ni/Al(2)O(3) during the reverse water-gas shift reaction. This work proposes that the formation rate of carbon deposition depends closely on ensemble control, suggesting that the ensemble size necessary to form carbon may be approximately 0.5 potassium atoms. The results of CO(2) temperature-programmed desorption provide strong evidence that the new adsorption sites for CO(2) created on Ni-K/Al(2)O(3) closely depend upon the synthesis of carbon nanofibers. It is found that some potassium-related active phases obtained by calcination and reduction pretreatments can participate in the carbon deposition reaction. The formation pathway for carbon deposition suggests that the main source of carbon deposition is CO(2) and that the pathway is independent of the reaction products CO and CH(4) in the reverse water-gas shift reaction.

  14. Synthesis and electrochemical performance of ruthenium oxide-coated carbon nanofibers as anode materials for lithium secondary batteries

    Science.gov (United States)

    Hyun, Yura; Choi, Jin-Yeong; Park, Heai-Ku; Lee, Chang-Seop

    2016-12-01

    In this study, ruthenium oxide (RuO2) coated carbon nanofibers (CNFs) were synthesized and applied as anode materials of Li secondary batteries. The CNFs were grown on Ni foam via chemical vapor deposition (CVD) method after CNFs/Ni foam was put into the 0.01 M RuCl3 solution. The ruthenium oxide-coated CNFs/Ni foam was dried in a dryer at 80 °C. The morphologies, compositions, and crystal quality of RuO2/CNFs/Ni foam were characterized by SEM, EDS, XRD, Raman spectroscopy, and XPS. The electrochemical characteristics of RuO2/CNFs/Ni foam as anode of Li secondary batteries were investigated using three-electrode cell. The RuO2/CNFs/Ni foam was directly employed as a working electrode without any binder, and lithium foil was used as the counter and reference electrodes. LiClO4 (1 M) was employed as electrolyte and dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge/discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. In particular, synthesized RuO2/CNFs/Ni foam showed the highest retention rate (47.4%). The initial capacity (494 mAh/g) was reduced to 234 mAh/g after 30 cycles.

  15. Carbon Nanofibers Have IgE Adjuvant Capacity but Are Less Potent Than Nanotubes in Promoting Allergic Airway Responses

    Directory of Open Access Journals (Sweden)

    Unni Cecilie Nygaard

    2013-01-01

    Full Text Available There is a growing concern for the possible health impact of nanoparticles. The main objective of this study was to investigate the allergy-promoting capacity of four different carbon nanofiber (CNF samples in an injection and an airway mouse model of allergy. Secondly, the potency of the CNF was compared to the previously reported allergy-promoting capacity of carbon nanotubes (CNT in the airway model. Ultrafine carbon black particles (ufCBP were used as a positive control. Particles were given together with the allergen ovalbumin (OVA either by subcutaneous injection into the footpad or intranasally to BALB/cA mice. After allergen booster, OVA-specific IgE, IgG1, and IgG2a in serum were measured. In the airway model, inflammation was determined as influx of inflammatory cells (eosinophils, neutrophils, lymphocytes, and macrophages and by mediators (MCP-1 and TNF-α present in bronchoalveolar fluid (BALF. CNF and CNT both increased OVA-specific IgE levels in the two models, but in the airway model, the CNT gave a significantly stronger IgE response than the CNF. Furthermore, the CNT and not the CNF promoted eosinophil lung inflammation. Our data therefore suggest that nanotube-associated properties are particularly potent in promoting allergic responses.

  16. Carbon nanofibers with radially grown graphene sheets derived from electrospinning for aqueous supercapacitors with high working voltage and energy density.

    Science.gov (United States)

    Zhao, Lei; Qiu, Yejun; Yu, Jie; Deng, Xianyu; Dai, Chenglong; Bai, Xuedong

    2013-06-07

    Improvement of energy density is an urgent task for developing advanced supercapacitors. In this paper, aqueous supercapacitors with high voltage of 1.8 V and energy density of 29.1 W h kg(-1) were fabricated based on carbon nanofibers (CNFs) and Na2SO4 electrolyte. The CNFs with radially grown graphene sheets (GSs) and small average diameter down to 11 nm were prepared by electrospinning and carbonization in NH3. The radially grown GSs contain between 1 and a few atomic layers with their edges exposed on the surface. The CNFs are doped with nitrogen and oxygen with different concentrations depending on the carbonizing temperature. The supercapacitors exhibit excellent cycling performance with the capacity retention over 93.7% after 5000 charging-discharging cycles. The unique structure, possessing radially grown GSs, small diameter, and heteroatom doping of the CNFs, and application of neutral electrolyte account for the high voltage and energy density of the present supercapacitors. The present supercapacitors are of high promise for practical application due to the high energy density and the advantages of neutral electrolyte including low cost, safety, low corrosivity, and convenient assembly in air.

  17. Nitrogen-doped carbon-embedded TiO2 nanofibers as promising oxygen reduction reaction electrocatalysts

    Science.gov (United States)

    Hassen, D.; Shenashen, M. A.; El-Safty, S. A.; Selim, M. M.; Isago, H.; Elmarakbi, A.; El-Safty, A.; Yamaguchi, H.

    2016-10-01

    The development of inexpensive and effective electrocatalysts for oxygen reduction reaction (ORR) as a substitute for commercial Pt/C catalyst is an important issue in fuel cells. In this paper, we report on novel fabrication of self-supported nitrogen-doped carbon-supported titanium nanofibers (Nsbnd TiO2@C) and carbon-supported titanium (TiO2@C) electrocatalysts via a facile electrospinning route. The nitrogen atom integrates physically and homogenously into the entire carbon-titanium structure. We demonstrate the catalytic performance of Nsbnd TiO2@C and TiO2@C for ORR under alkaline conditions in comparison with Pt/C catalyst. The Nsbnd TiO2@C catalyst shows excellent ORR reactivity and durability. Interestingly, among all the catalysts used in this ORR, Nsbnd TiO2@C-0.75 exhibits remarkable competitive oxygen reduction activity in terms of current density and onset potential, as well as superior methanol tolerance. Such tolerance attributes to maximizing the diffusion of trigger pulse electrons during catalytic reactions because of enhanced electronic features. Results indicate that our fabrication strategy can provide an opportunity to produce a simple, efficient, cost-effective, and promising ORR electrocatalyst for practical applications in energy conversion and storage technologies.

  18. Magnetic properties of NiFe{sub 2}O{sub 4}/carbon nanofibers from Venezuelan petcoke

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cañizales, Edgard [Área de Análisis Químico Inorgánico, PDVSA, INTEVEP, Los Teques 1070-A (Venezuela, Bolivarian Republic of)

    2015-05-01

    NiFe{sub 2}O{sub 4}/carbon nanofibers (NiFe{sub 2}O{sub 4}/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe{sub 2}O{sub 4} as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe{sub 2}O{sub 4}/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs. - Highlights: • NiFe{sub 2}O{sub 4}/CNFs have been synthesized by hydrothermal method using petroleum coke. • Nickel ferrite nanoparticles were used as the catalyst. • HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. • The size of the nanoparticles defines the diameter of the CNFs.

  19. Preparation and electrochemical performance of hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets for a battery-supercapacitor hybrid system

    Science.gov (United States)

    Choi, Hong Soo; Kim, TaeHoon; Im, Ji Hyuk; Park, Chong Rae

    2011-10-01

    Hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li4Ti5O12, and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li4Ti5O12/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g - 1 at 4000 mA g - 1 as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg - 1 and 22 W kg - 1 at power densities of 50 W kg - 1 and 4000 W kg - 1, respectively, which are superior to the values observed for the {AC} \\parallel {AC} symmetric electrode system.

  20. Synthesis and characterization of well-aligned carbon nitrogen nanotubes by microwave plasma chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    马旭村; 徐贵昌; 王恩哥

    2000-01-01

    Well-aligned carbon nitrogen nanotube films have been synthesized successfully on meso-porous silica substrates by microwave plasma chemical vapor deposition (MWPCVD) method. Studies on their morphology, structure, and composition by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX), respectively, indicate that these nanotubes consist of linearly polymerized carbon nitrogen nanobells, and the nitrogen atoms have been doped into carbon netweork to form a new structure C1-xNx( x = 0.16±0.01). X-ray photoelectron spectroscopy (XPS) results of the samples further demonstrate that carbon bonds cova-lently with nitrogen in all the carbon nitrogen nanotube films.

  1. Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.

    Science.gov (United States)

    Sarkar, Sourangsu; Zou, Jianhua; Liu, Jianhua; Xu, Chengying; An, Linan; Zhai, Lei

    2010-04-01

    Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics.

  2. Electrokinetics of scalable, electric-field-assisted fabrication of vertically aligned carbon-nanotube/polymer composites

    Science.gov (United States)

    Castellano, Richard J.; Akin, Cevat; Giraldo, Gabriel; Kim, Sangil; Fornasiero, Francesco; Shan, Jerry W.

    2015-06-01

    Composite thin films incorporating vertically aligned carbon nanotubes (VACNTs) offer promise for a variety of applications where the vertical alignment of the CNTs is critical to meet performance requirements, e.g., highly permeable membranes, thermal interfaces, dry adhesives, and films with anisotropic electrical conductivity. However, current VACNT fabrication techniques are complex and difficult to scale up. Here, we describe a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT composites. Multiwall-carbon nanotubes are dispersed in a polymeric matrix, aligned with an alternating-current (AC) electric field, and electrophoretically concentrated to one side of the thin film with a direct-current (DC) component to the electric field. This approach enables the fabrication of highly concentrated, individually aligned nanotube composites from suspensions of very dilute ( ϕ = 4 × 10 - 4 ) volume fraction. We experimentally investigate the basic electrokinetics of nanotube alignment under AC electric fields, and show that simple models can adequately predict the rate and degree of nanotube alignment using classical expressions for the induced dipole moment, hydrodynamic drag, and the effects of Brownian motion. The composite AC + DC field also introduces complex fluid motion associated with AC electro-osmosis and the electrochemistry of the fluid/electrode interface. We experimentally probe the electric-field parameters behind these electrokinetic phenomena, and demonstrate, with suitable choices of processing parameters, the ability to scalably produce large-area composites containing VACNTs at number densities up to 1010 nanotubes/cm2. This VACNT number density exceeds that of previous electric-field-fabricated composites by an order of magnitude, and the surface-area coverage of the 40 nm VACNTs is comparable to that of chemical-vapor-deposition-grown arrays of smaller-diameter nanotubes.

  3. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    Science.gov (United States)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  4. Behavior of oxidized platinum nanoparticles on an aligned carbon nanotube forest

    Science.gov (United States)

    Matsuda, Keita; Norimatsu, Wataru; Arai, Shigeo; Kusunoki, Michiko

    2016-10-01

    We observed and analyzed the behavior of platinum nanoparticles (PtNPs) supported on aligned-carbon nanotubes (CNTs) at high temperatures by X-ray photoelectron spectroscopy and high-resolution transmission electron microscope observations. We found that the PtNPs moved toward the inner-side along each CNT on which they were deposited. The mechanism of this behavior is related to the redox reaction of Pt with the carbon atoms in the CNT. We also performed in-situ observation of this process at a high temperature using an environmental transmission electron microscope under an oxygen atmosphere. We found that the PtNPs penetrated down into a high-density aligned CNT forest along the tube axis and that the PtNPs changed their shape to fit the structure of the CNTs during their movement.

  5. Low Temperature Growth of Vertically Aligned Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Method

    Institute of Scientific and Technical Information of China (English)

    M.R. Atiyan; D.R. Awang Biak; F. Ahmadun; I.S. Ahamad; F. Mohd Yasin; H. Mohamed Yusoff

    2011-01-01

    Synthesis of carbon nanotubes (CNTs) below 600℃ using supporting catalyst chemical vapor deposition method was reported by many research groups. However, the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced. In this work, the effects of varying the preheating temperature on the synthesis of CNT were investigated. The reaction temperature was set at 570℃. The preheating set temperature was varied from 150 to 400℃ at 50℃ interval. Three O-ring shape heating mantels were used as heating source for the preheater. In situ monitoring device was used to observe the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. Vertically aligned CNTs were synthesized when the preheating temperature was set at 400℃. When the preheating temperature was increased up to 400℃, both the length and the alignment of CNTs produced were improved.

  6. Fabrication of flexible hierarchical porous nitrogen-doped carbon nanofiber films for application in binder-free supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Kaibing, E-mail: kbhuang8888@163.com; Yao, Yiyuan; Yang, Xiuwen; Chen, Zhenhua; Li, Min

    2016-02-01

    Hierarchical porous nitrogen-doped carbon nanofiber (HPNCNF) films were prepared via a simple electrospinning process, in which polyacrylonitrile and silicone surfactants were adopted as carbon source and porogen, respectively, followed by a thermal treatment. The morphology, chemical composition, and porosity of the HPNCNFs were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and nitrogen adsorption–desorption experiments. The as-prepared HPNCNFs with a specific surface area of 656 m{sup 2} g{sup −1}, a hierarchical pore structure, and a nitrogen content of 8.1 at% showed a specific capacitance of 289 F g{sup −1} in a 6 mol L{sup −1} KOH aqueous solution with excellent cycle durability, making HPNCNF films a promising electrode material for a future application in supercapacitors. - Highlights: • HPNCNF films are prepared by electrospinning followed by thermal treatment. • Silicone surfactants are adopted as porogen to prepare HPNCNF films. • The HPNCNF films show a specific capacitance of 289 F g{sup −1} at a current density of 0.2 A g{sup −1}.

  7. Controlled Synthesis and Functionalization of Vertically-Aligned Carbon Nanotubes for Multifunctional Applications

    Science.gov (United States)

    2015-05-07

    cluster and hollow microfibers by multicomponent self-assembling of citrate stabilized gold nanoparticles with temperature-responsive amphiphilic...assembling of citrate stabilized gold nanoparticles with temperature-responsive amphiphilic dendrimers" J. Mater. Chem. 22, 13365-13373, 2012. 35. D. Yu...AFRL-OSR-VA-TR-2015-0108 CONTROLLED SYNTHESIS AND FUNCTIONALIZATION OF VERTICALLY-ALIGNED CARBON NANOTUBES FOR MULTIFUNCTIONAL APPLICATIONS LIMING

  8. Alignment of Multi-walled Carbon Nanotubes in Polyacrylonitrile Fibers by Mechanical Drawing

    Institute of Scientific and Technical Information of China (English)

    WANG Biao; WEN Zhi-wei; PENG Kun; WANG Hua-ping

    2010-01-01

    Polyacrylonitrile(PAN)/multi-waUed carbon nanotubes(MWNTs)narmcomposites were prepared by an in-situ polymerization method and the fibers from these composites were obtained by a wet-spinning process.The orientation behavior of MWNTs in the PAN fibers was investigated by X-ray diffraction and sound velocity methods.The dispersion and the alignment of the nanotubes were also studied by scanning electron microscopy.

  9. Tritrichomonas foetus adhere to superhydrophilic vertically aligned multi-walled carbon nanotube surface

    Energy Technology Data Exchange (ETDEWEB)

    Moreira Machado, Susane [Laboratorio de Biologia Celular e Tecidual, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi 2911, 12244-000, Sao Jose dos Campos, SP (Brazil); Oliveira Lobo, Anderson, E-mail: loboao@yahoo.com [Laboratorio de Nanotecnologia Biomedica (NanoBio), Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi 2911, Sao Jose dos Campos, 12244-000, SP (Brazil); Laboratorio de Espectroscopia Vibracional Biomedica, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Avenida Shishima Hifumi, 2911, CEP 12244-000, Sao Jose dos Campos, SP (Brazil); Bueno Loureiro Sapucahy, Ariel [Laboratorio de Biologia Celular e Tecidual, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi 2911, 12244-000, Sao Jose dos Campos, SP (Brazil); Marciano, Fernanda Roberta [Laboratorio de Nanotecnologia Biomedica (NanoBio), Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi 2911, Sao Jose dos Campos, 12244-000, SP (Brazil); Laboratorio de Espectroscopia Vibracional Biomedica, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Avenida Shishima Hifumi, 2911, CEP 12244-000, Sao Jose dos Campos, SP (Brazil); Corat, Evaldo Jose [Instituto Nacional de Pesquisas Espaciais (INPE), Laboratorio Associado de Sensores e Materiais (LAS), Av. dos Astronautas 1758, Sao Jose dos Campos, 12227-010 SP (Brazil); Soares da Silva, Newton [Laboratorio de Biologia Celular e Tecidual, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi 2911, 12244-000, Sao Jose dos Campos, SP (Brazil)

    2011-10-10

    For the first time, we show that Tritrichomonas foetus can adhere on superhydrophilic vertically aligned carbon nanotubes (VACNT) films. Scanning electron microscopy shows an unusual adhesion with a higher membrane filopodium projection in all directions, directly attached to superhydrophilic VACNT tips. Highlights: {yields} This is a new method to study the T. foetus adhesion mechanism. {yields} SEM images and interfacial adhesion force show a high adhesion level. {yields} It is very important for future understanding mechanism adhesion and protein expression.

  10. Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors

    OpenAIRE

    2011-01-01

    Here we report the fabrication and characterization of pH sensors using aligned single-walled carbon nanotubes (SWNTs). The SWNTs are dispersed in deionized (DI) water after chemical functionalization and filtration. They are deposited and organized on silicon substrates with the dielectrophoresis process. Electrodes with “teeth”-like patterns—fabricated with photolithography and wet etching—are used to generate concentrated electric fields and strong dielectrophoretic forces for the SWNTs to...

  11. A comparative study of the field emission properties of aligned carbon nanostructures films, from carbon nanotubes to diamond

    OpenAIRE

    Le Normand, Francois; Cojocaru, Costel Sorin; Fleaca, Claudiu; Li, J. Q.; Vincent, Pascal; Pirio, Gilles; Gangloff, Laurent; Nedellec, Yanick; Legagneux, Pierre

    2007-01-01

    International audience; The electron field emission properties of different graphitic and diamond-like nanostructures films are compared. They are prepared in the same CVD chamber on SiO{2}/Si(100) and Si(100) flat surfaces, respectively. These nanostructures are thoroughly characterized by scanning electron emission (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Films of dense aligned carbon nan...

  12. Estimation of the poly (ε-caprolactone [PCL] and α-cyclodextrin [α-CD] stoichiometric ratios in their inclusion complexes [ICs], and evaluation of porosity and fiber alignment in PCL nanofibers containing these ICs

    Directory of Open Access Journals (Sweden)

    Ganesh Narayanan

    2015-12-01

    Full Text Available This paper describes the utilization of Proton-Nuclear Magnetic Resonance spectroscopy (1H NMR to quantify the stoichiometric ratios between poly (ε-caprolactone [PCL] and α-cyclodextrin (α-CD present in their non-stoichiometric inclusion complexes [(n-s-ICs]. This paper further describes the porosity and fiber alignment of PCL nanofibers nucleated by the [(n-s-ICs] during electrospinning. 1H NMR indicated that the two non-stoichiometric inclusion complexes utilized in this study had differing stoichiometric ratios that were closely similar to those of the starting ratios used to make them. Studies on porosity and fiber alignments were conducted on the scanning electron microscope images using ImageJ. The data indicates that both fiber alignment as well as porosity values remain almost the same over all the samples. Thus we can conclude the improvement in mechanical properties was due only to the loading of the ICs, and their subsequent interaction with bulk unthreaded PCL.

  13. Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2010-08-03

    A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

  14. Label-free electronic detection of bio-toxins using aligned carbon nanotubes.

    Science.gov (United States)

    Palaniappan, Al; Goh, W H; Fam, D W H; Rajaseger, G; Chan, C E Z; Hanson, B J; Moochhala, S M; Mhaisalkar, S G; Liedberg, B

    2013-05-15

    A facile route for sensitive label-free detection of bio-toxins using aligned single walled carbon nanotubes is described. This approach involves patterning of a catalyst on the surface of a quartz substrate using a sub-100 μm stripe-patterned polydimethylsiloxane stamp for aligned carbon nanotube generation followed by fabrication of field effect transistor (FET). Atomic force microscopy, field emission scanning electron microscopy and Raman spectroscopy are employed to characterize the synthesized nanotubes. Unlike previous reports, the adopted approach enables direct electronic detection of bio-toxins with sensitivities comparable to ELISA. As a proof of concept, the fabricated FET responds to nM concentration levels (with a LOD of ∼2 nM) of epsilon toxin produced by Clostridium perfringens and a prominent food toxin. This facile approach could be customized to detect other classes of toxins and biomarkers upon appropriate functionalization of the aligned carbon nanotubes. Finally, we demonstrate the use of the FET-platform for detection of toxin in more complex matrices such as orange juice.

  15. Aerosynthesis: Growth of Vertically-aligned Carbon Nanofibres with Air DC Plasma

    Directory of Open Access Journals (Sweden)

    A. Kodumagulla

    2014-03-01

    Full Text Available Vertically-aligned carbon nanofibres (VACNFs have been synthesized in a mixture of acetone and air using catalytic DC plasma-enhanced chemical vapour deposition. Typically, ammonia or hydrogen is used as an etchant gas in the mixture to remove carbon that otherwise passivates the catalyst surface and impedes growth. Our demonstration of the use of air as the etchant gas opens up the possibility that ion etching could be sufficient to maintain the catalytic activity state during synthesis. It also demonstrates a path toward growing VACNFs in the open atmosphere.

  16. Adaptive Neuro-Fuzzy Modeling of Mechanical Behavior for Vertically Aligned Carbon Nanotube Turfs

    Institute of Scientific and Technical Information of China (English)

    Mohammad A1-Khedher; Charles Pezeshki; Jeanne McHale; GFritz Knorr

    2011-01-01

    Several characterization methods have been developed to investigate the mechanical and structural properties of vertically aligned carbon nanotubes (VACNTs). Establishing analytical models at nanoscale to interpret these properties is complicated due to the nonuniformity and irregularity in quality of as-grown samples.In this paper, we propose a new methodology to investigate the correlation between indentation resistance of multi-wall carbon nanotube (MWCNT) turfs, Raman spectra and the geometrical properties of the turf structure using adaptive neuro-fuzzy phenomenological modeling. This methodology yields a novel approach for modeling at the nanoscale by evaluating the effect of structural morphologies on nanomaterial properties using Raman spectroscopy.

  17. Nitrogen-Doped Carbon Nanoparticle-Carbon Nanofiber Composite as an Efficient Metal-Free Cathode Catalyst for Oxygen Reduction Reaction.

    Science.gov (United States)

    Panomsuwan, Gasidit; Saito, Nagahiro; Ishizaki, Takahiro

    2016-03-23

    Metal-free nitrogen-doped carbon materials are currently considered at the forefront of potential alternative cathode catalysts for the oxygen reduction reaction (ORR) in fuel cell technology. Despite numerous efforts in this area over the past decade, rational design and development of a new catalyst system based on nitrogen-doped carbon materials via an innovative approach still present intriguing challenges in ORR catalysis research. Herein, a new kind of nitrogen-doped carbon nanoparticle-carbon nanofiber (NCNP-CNF) composite with highly efficient and stable ORR catalytic activity has been developed via a new approach assisted by a solution plasma process. The integration of NCNPs and CNFs by the solution plasma process can lead to a unique morphological feature and modify physicochemical properties. The NCNP-CNF composite exhibits a significantly enhanced ORR activity through a dominant four-electron pathway in an alkaline solution. The enhancement in ORR activity of NCNP-CNF composite can be attributed to the synergistic effects of good electron transport from highly graphitized CNFs as well as abundance of exposed catalytic sites and meso/macroporosity from NCNPs. More importantly, NCNP-CNF composite reveals excellent long-term durability and high tolerance to methanol crossover compared with those of a commercial 20 wt % supported on Vulcan XC-72. We expect that NCNP-CNF composite prepared by this synthetic approach can be a promising metal-free cathode catalyst candidate for ORR in fuel cells and metal-air batteries.

  18. 纳米纤维束的制备及力学性能研究%Fabrication of braided wires from aligned nanofibers and analysis of their mechanical performance

    Institute of Scientific and Technical Information of China (English)

    胡雯; 黄争鸣

    2009-01-01

    PU nanofibers were fabricated by means of electrospinning and were collected undirectionally using a rotating disk. The relationship between a rotating speed and fiber alignment was studied. The collected fiber bundles were post processing treated using the techniques such as heating, stretching, twisting, and preforming, before they were made into a braided wire. Optimal post processing parameters were obtained in order to achieve the highest mechanical properties for the fiber bundles. It was shown that the braided wires had a much better mechanical performance than that of the unidirectionally collected fiber bundles before the post treatments, and even better than that after the treatments. This high mechanical behavior implies that the braided wires based on aligned electrospun nanofibers will have potential applications in textile and biomedical fields.%采用静电纺丝法制备出了纳米级、亚微米级纤维,采用尖角圆盘收集成具有定向排列的单向纤维束,考察了圆盘转速对纤维定向性的影响.为提高纤维的强度和模量,对收集到的纤维束进行了热处理、拉伸、加捻、定型等后处理工艺,再将多股定型的纤维束编织成线.研究了上述工艺参数对纤维束力学性能的影响,选取最佳工艺参数编织纤维束,并研究了编织线的力学性能.良好的性能预示其在纺织、生物医学等领域具有潜在的应用前景.

  19. Quantum dot decorated aligned carbon nanotube bundles for a performance enhanced photoswitch

    Science.gov (United States)

    Sreejith, Sivaramapanicker; Hansen, Reinack; Joshi, Hrishikesh; Kutty, R. Govindan; Liu, Zheng; Zheng, Lianxi; Yang, Jinglei; Zhao, Yanli

    2016-04-01

    Photoactive materials that are triggered by the irradiation of light to generate an electrical response provide an ecofriendly platform to afford efficient power sources and switches. A chemical assembly of well-known elements with aligned carbon nanotube bundles is reported here, which was employed to form an efficient photo-induced charge transfer device. The primary elements of this device are ultra-long multi-walled carbon nanotube (MWCNT) bundles, polyaniline (PANI) thin film coating, and CdSe quantum dots (QDs). Highly ordered and horizontally aligned MWCNT bundles were coated with PANI to enhance charge transfer properties of active QDs in this platform. The obtained device (CdSe-MWCNT@PANI) constructed on a silicon base exhibits highly efficient power conversion capabilities owing to the aligned MWCNT bundle assisted enhanced charge transport pathways generated within the device. The device also shows a short circuit current density (Jsc) of 9.81 mA cm-2 and an open circuit voltage (Voc) of 0.46 V. The power conversion efficiency (PCE) of the device is 5.41%, and the current response is quite stable, highly responsive, and reproducible.Photoactive materials that are triggered by the irradiation of light to generate an electrical response provide an ecofriendly platform to afford efficient power sources and switches. A chemical assembly of well-known elements with aligned carbon nanotube bundles is reported here, which was employed to form an efficient photo-induced charge transfer device. The primary elements of this device are ultra-long multi-walled carbon nanotube (MWCNT) bundles, polyaniline (PANI) thin film coating, and CdSe quantum dots (QDs). Highly ordered and horizontally aligned MWCNT bundles were coated with PANI to enhance charge transfer properties of active QDs in this platform. The obtained device (CdSe-MWCNT@PANI) constructed on a silicon base exhibits highly efficient power conversion capabilities owing to the aligned MWCNT bundle assisted

  20. Aligned carbon nanotube-silicon sheets: a novel nano-architecture for flexible lithium ion battery electrodes.

    Science.gov (United States)

    Fu, Kun; Yildiz, Ozkan; Bhanushali, Hardik; Wang, Yongxin; Stano, Kelly; Xue, Leigang; Zhang, Xiangwu; Bradford, Philip D

    2013-09-25

    Aligned carbon nanotube sheets provide an engineered scaffold for the deposition of a silicon active material for lithium ion battery anodes. The sheets are low-density, allowing uniform deposition of silicon thin films while the alignment allows unconstrained volumetric expansion of the silicon, facilitating stable cycling performance. The flat sheet morphology is desirable for battery construction.

  1. Mechanical properties and cellular response of novel electrospun nanofibers for ligament tissue engineering: Effects of orientation and geometry.

    Science.gov (United States)

    Pauly, Hannah M; Kelly, Daniel J; Popat, Ketul C; Trujillo, Nathan A; Dunne, Nicholas J; McCarthy, Helen O; Haut Donahue, Tammy L

    2016-08-01

    Electrospun nanofibers are a promising material for ligamentous tissue engineering, however weak mechanical properties of fibers to date have limited their clinical usage. The goal of this work was to modify electrospun nanofibers to create a robust structure that mimics the complex hierarchy of native tendons and ligaments. The scaffolds that were fabricated in this study consisted of either random or aligned nanofibers in flat sheets or rolled nanofiber bundles that mimic the size scale of fascicle units in primarily tensile load bearing soft musculoskeletal tissues. Altering nanofiber orientation and geometry significantly affected mechanical properties; most notably aligned nanofiber sheets had the greatest modulus; 125% higher than that of random nanofiber sheets; and 45% higher than aligned nanofiber bundles. Modifying aligned nanofiber sheets to form aligned nanofiber bundles also resulted in approximately 107% higher yield stresses and 140% higher yield strains. The mechanical properties of aligned nanofiber bundles were in the range of the mechanical properties of the native ACL: modulus=158±32MPa, yield stress=57±23MPa and yield strain=0.38±0.08. Adipose derived stem cells cultured on all surfaces remained viable and proliferated extensively over a 7 day culture period and cells elongated on nanofiber bundles. The results of the study suggest that aligned nanofiber bundles may be useful for ligament and tendon tissue engineering based on their mechanical properties and ability to support cell adhesion, proliferation, and elongation.

  2. Effects of reaction conditions on hydrogen production and carbon nanofiber properties generated by methane decomposition in a fixed bed reactor using a NiCuAl catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suelves, I.; Pinilla, J.L.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma Castan, 4, 50015 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Marie Curie 2, 28049 Madrid (Spain)

    2009-07-01

    In this paper, the results obtained in the catalytic decomposition of methane in a fixed bed reactor using a NiCuAl catalyst prepared by the fusion method are presented. The influences of reaction temperature and space velocity on hydrogen concentration in the outlet gases, as well as on the properties of the carbon produced, have been investigated. Reaction temperature and the space velocity both increase the reaction rate of methane decomposition, but also cause an increase in the rate of catalyst deactivation. Under the operating conditions used, the carbon product is mainly deposited as nanofibers with textural properties highly correlated with the degree of crystallinity. (author)

  3. Factoring-in agglomeration of carbon nanotubes and nanofibers for better prediction of their toxicity versus asbestos

    Directory of Open Access Journals (Sweden)

    Murray Ashley R

    2012-04-01

    Full Text Available Abstract Background Carbon nanotubes (CNT and carbon nanofibers (CNF are allotropes of carbon featuring fibrous morphology. The dimensions and high aspect ratio of CNT and CNF have prompted the comparison with naturally occurring asbestos fibers which are known to be extremely pathogenic. While the toxicity and hazardous outcomes elicited by airborne exposure to single-walled CNT or asbestos have been widely reported, very limited data are currently available describing adverse effects of respirable CNF. Results Here, we assessed pulmonary inflammation, fibrosis, oxidative stress markers and systemic immune responses to respirable CNF in comparison to single-walled CNT (SWCNT and asbestos. Pulmonary inflammatory and fibrogenic responses to CNF, SWCNT and asbestos varied depending upon the agglomeration state of the particles/fibers. Foci of granulomatous lesions and collagen deposition were associated with dense particle-like SWCNT agglomerates, while no granuloma formation was found following exposure to fiber-like CNF or asbestos. The average thickness of the alveolar connective tissue - a marker of interstitial fibrosis - was increased 28 days post SWCNT, CNF or asbestos exposure. Exposure to SWCNT, CNF or asbestos resulted in oxidative stress evidenced by accumulations of 4-HNE and carbonylated proteins in the lung tissues. Additionally, local inflammatory and fibrogenic responses were accompanied by modified systemic immunity, as documented by decreased proliferation of splenic T cells ex vivo on day 28 post exposure. The accuracies of assessments of effective surface area for asbestos, SWCNT and CNF (based on geometrical analysis of their agglomeration versus estimates of mass dose and number of particles were compared as predictors of toxicological outcomes. Conclusions We provide evidence that effective surface area along with mass dose rather than specific surface area or particle number are significantly correlated with toxicological

  4. Dipole Alignment at the Carbon Nanotube and Methyl Ammonium Lead Iodide Perovskite Interface

    Energy Technology Data Exchange (ETDEWEB)

    Przepioski, Joshua [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-28

    This work correlates resonant peaks from first principles calculation on ammonia (NH3) Nitrogen 1s x-ray absorption spectroscopy (XAS) within the methyl ammonium lead iodide perovskite (CH3NH3PbI3), and proposes a curve to determine the alignment of the methyl ammonium dipole if there exists angular dependence. The Nitrogen 1s XAS was performed at varying incident angles on the perovskite with and without a carbon nanotube (CNT) interface produced from an ultrasonic spray deposition. We investigated the peak contribution from PbI2 and the poly(9,9-dioctylfluorene- 2,7-diyl) with bipyridine (PFO-BPy) wrapped around the CNT, and used normalization techniques to better identify the dipole alignment. There was angular dependence on samples containing the CNT interface suggesting an existing dipole alignment, but there was no angular dependence on the perovskite samples alone; however, more normalization techniques and experimental work must be performed in order to ensure its validity and to better describe its alignment, and possible controlling factors.

  5. Dipole Alignment at the Carbon Nanotube and Methyl Ammonium Lead Trihalide Perovskite Interface - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Przepioski, Joshua [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-25

    This work correlates resonant peaks from first principles calculation on ammonia (NH3) Nitrogen 1s x-ray absorption spectroscopy (XAS) within the methyl ammonium lead iodide perovskite (CH3NH3PbI3), and proposes a curve to determine the alignment of the methyl ammonium dipole if there exists angular dependence. The Nitrogen 1s XAS was performed at varying incident angles on the perovskite with and without a carbon nanotube (CNT) interface produced from an ultrasonic spray deposition. We investigated the peak contribution from PbI2 and the poly(9,9-dioctylfluorene-2,7-diyl) with bipyridine (PFO-BPy) wrapped around the CNT, and used normalization techniques to better identify the dipole alignment. There was angular dependence on samples containing the CNT interface suggesting an existing dipole alignment, but there was no angular dependence on the perovskite samples alone; however, more normalization techniques and experimental work must be performed in order to ensure its validity and to better describe its alignment, and possible controlling factors.

  6. Electrodeposition of Various Au Nanostructures on Aligned Carbon Nanotubes as Highly Sensitive Nanoelectrode Ensembles

    Science.gov (United States)

    Fayazfar, H.; Afshar, A.; Dolati, A.

    2015-05-01

    An efficient method has been developed to synthesize well-aligned multi-walled carbon nanotubes (MWCNTs) on a conductive Ta substrate by chemical vapor deposition. Free-standing MWCNTs arrays were functionalized through electrochemical oxidation with the formation of hydroxyl and carboxyl functional groups. Facile template-free electrochemical routes were then developed for the shape-selective synthesis of less-common Au nanostructures, including flower, sphere, dendrite, rod, sheet, and cabbage onto the aligned MWCNTs at room temperature. Especially, among all the synthesis methods for Au nanocrystals, this is the first report using electrochemical technique to synthesize wide variety shapes of gold nanostructures (GNs) onto the aligned MWCNTs. The morphology of electrodeposited Au nanostructures was controlled by adjustment of the deposition time and potential, the number of potential cycles, the kind of deposition bath, and electrodeposition method. Transmission electron microscopy and field-emission scanning electron microscopy were used to characterize the products. Cyclic voltammograms showed that the MWCNT/Ta electrodes modified with GNs have higher sensitivity compared to the unmodified electrodes in the presence of Fe2+/Fe3+ redox couple. These kinds of aligned-CNT/Au nanostructure hybrid materials introduced by these efficient and simple electrochemical methods could lead to the development of a new generation device for ultrasensitive catalytic and biological application.

  7. Directly measuring of thermal pulse transfer in one-dimensional highly aligned carbon nanotubes.

    Science.gov (United States)

    Zhang, Guang; Liu, Changhong; Fan, Shoushan

    2013-01-01

    Using a simple and precise instrument system, we directly measured the thermo-physical properties of one-dimensional highly aligned carbon nanotubes (CNTs). A kind of CNT-based macroscopic materials named super aligned carbon nanotube (SACNT) buckypapers was measured in our experiment. We defined a new one-dimensional parameter, the "thermal transfer speed" to characterize the thermal damping mechanisms in the SACNT buckypapers. Our results indicated that the SACNT buckypapers with different densities have obviously different thermal transfer speeds. Furthermore, we found that the thermal transfer speed of high-density SACNT buckypapers may have an obvious damping factor along the CNTs aligned direction. The anisotropic thermal diffusivities of SACNT buckypapers could be calculated by the thermal transfer speeds. The thermal diffusivities obviously increase as the buckypaper-density increases. For parallel SACNT buckypapers, the thermal diffusivity could be as high as 562.2 ± 55.4 mm(2)/s. The thermal conductivities of these SACNT buckypapers were also calculated by the equation k = Cpαρ.

  8. Rainbow channeling of protons in very short carbon nanotubes with aligned Stone–Wales defects

    Energy Technology Data Exchange (ETDEWEB)

    Ćosić, M., E-mail: mcosic@vinca.rs [Laboratory of Physics, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Petrović, S. [Laboratory of Physics, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Bellucci, S. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy)

    2016-01-15

    In this paper proton channeling through armchair single-walled-carbon-nanotubes (SWCNTs) with aligned Stone–Wales defects has been investigated. The energy of the proton beam was 1 GeV, while the lengths of the SWCNTs have been varied from 200 nm up to 1000 nm. The linear density of aligned defects has been varied in the whole range, from minimally up to maximally possible values. Here are presented results of a detailed morphological analysis concerning: the formation, evolution and interaction of the nanotube rainbows. The potential of the SWCNT has been constructed from Molère’s expression of the Thomas–Fermi’s proton–carbon interaction-energy, using the approximation of the continuous atomic string. Trajectories of the channeled protons were obtained by solving the corresponding classical equations of motions. Distributions of the transmitted protons were obtained by the Monte-Carlo simulation. The shape of angular distributions has been explained in the framework of the theory of nanotube rainbows. The aim of this study is also to investigate the applicability of the proton rainbow channeling for the characterization of nanotubes with aligned Stone–Wales defects.

  9. Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints

    Directory of Open Access Journals (Sweden)

    Davood Askari and Mehrdad N Ghasemi-Nejhad

    2012-01-01

    Full Text Available The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength using carbon nanotubes (CNTs as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.

  10. Rainbow channeling of protons in very short carbon nanotubes with aligned Stone-Wales defects

    Science.gov (United States)

    Ćosić, M.; Petrović, S.; Bellucci, S.

    2016-01-01

    In this paper proton channeling through armchair single-walled-carbon-nanotubes (SWCNTs) with aligned Stone-Wales defects has been investigated. The energy of the proton beam was 1 GeV, while the lengths of the SWCNTs have been varied from 200 nm up to 1000 nm. The linear density of aligned defects has been varied in the whole range, from minimally up to maximally possible values. Here are presented results of a detailed morphological analysis concerning: the formation, evolution and interaction of the nanotube rainbows. The potential of the SWCNT has been constructed from Molère's expression of the Thomas-Fermi's proton-carbon interaction-energy, using the approximation of the continuous atomic string. Trajectories of the channeled protons were obtained by solving the corresponding classical equations of motions. Distributions of the transmitted protons were obtained by the Monte-Carlo simulation. The shape of angular distributions has been explained in the framework of the theory of nanotube rainbows. The aim of this study is also to investigate the applicability of the proton rainbow channeling for the characterization of nanotubes with aligned Stone-Wales defects.

  11. Alumina-carbon nanofibers nanocomposites obtained by spark plasma sintering for proton exchange membrane fuel cell bipolar plates

    Energy Technology Data Exchange (ETDEWEB)

    Borrell, A.; Torrecillas, R. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN) Consejo Superior de Investigaciones Cientificas, Universidad de Oviedo, Principado de Asturias, Parque Tecnologico de Asturias, Llanera Asturias (Spain); Rocha, V.G.; Fernandez, A. [ITMA Materials Technology, Parque Tecnologico de Asturias, Llanera Asturias (Spain)

    2012-08-15

    There is an increasing demand of multifunctional materials for a wide variety of technological developments. Bipolar plates for proton exchange membrane fuel cells are an example of complex functionality components that must show among other properties high mechanical strength, electrical, and thermal conductivity. The present research explored the possibility of using alumina-carbon nanofibers (CNFs) nanocomposites for this purpose. In this study, it was studied for the first time the whole range of powder compositions in this system. Homogeneous powders mixtures were prepared and subsequently sintered by spark plasma sintering. The materials obtained were thoroughly characterized and compared in terms of properties required to be used as bipolar plates. The control on material microstructure and composition allows designing materials where mechanical or electrical performances are enhanced. A 50/50 vol.% alumina-CNFs composite appears to be a very promising material for this kind of application. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Flexible carbon nanofiber/polyvinylidene fluoride composite membranes as interlayers in high-performance Lithiumsbnd Sulfur batteries

    Science.gov (United States)

    Wang, Zhenhua; Zhang, Jing; Yang, Yuxiang; Yue, Xinyang; Hao, Xiaoming; Sun, Wang; Rooney, David; Sun, Kening

    2016-10-01

    Traditionally polyvinylidene fluoride membranes have been used in applications such as membrane distillation, wastewater treatment, desalination and separator fabrication. Within this work we demonstrate that a novel carbon nanofiber/polyvinylidene fluoride (CNF/PVDF) composite membrane can be used as an interlayer for Lithiumsbnd Sulfur (Lisbnd S) batteries yielding both high capacity and long cycling life. This PVDF membrane is shown to effectively separate dissolved lithium polysulfide with the high electronic conductivity CNF not only reducing the internal resistance in the sulfur cathode but also helping immobilize the polysulfide through its abundant nanospaces. The resulting Lisbnd S battery assembled with the CNF/PVDF composite membrane effectively solves the polysulfide permeation problem and exhibits excellent electrochemical performance. It is further shown that the CNF/PVDF electrode has an excellent cycling stability and retains a capacity of 768.6 mAh g-1 with a coulombic efficiency above 99% over 200 cycles at 0.5C, which is more than twice that of a cell without CNF/PVDF (374 mAh g-1). In addition, the low-cost raw materials and the simple preparation process of CNF/PVDF composite membrane is also amenable for industrial production.

  13. A hierarchical nanostructured carbon nanofiber-In2S3 photocatalyst with high photodegradation and disinfection abilities under visible light.

    Science.gov (United States)

    Gao, Peng; Li, An Ran; Tai, Ming Hang; Liu, Zhao Yang; Sun, Darren Delai

    2014-06-01

    Photocatalytic degradation of pollutants under visible light provides a new door to solve the water contamination problem by utilizing free and renewable sunlight. The search for highly efficient photocatalysts with hierarchical nanostructures remains crucial for accessing this new door. In this work, a new hierarchical nanostructured photocatalyst is designed and synthesized, for the first time, by anchoring In2S3 flower-like nanostructures on non-woven carbon nanofiber (CNF). The nanostructures of these CNF-In2S3 composites were fine-tuned, with the aim of achieving the highest photocatalytic activity under visible light. The formation mechanism of the hierarchical nanostructure is also investigated. The results indicate that the optimized hierarchical CNF-In2S3 photocatalyst is superior in photodegradation and disinfection efficiency to that of pure In2S3 under visible-light irradiation. The prominent photocatalytic activities of these hierarchical CNF-In2S3 photocatalysts can be attributed to the excellent properties of enhanced light absorption, large surface area, and efficient charge separation, which are all derived from the special three-dimensional hierarchical nanostructures. Therefore, this work presents the great potential of this hierarchical nanostructured CNF-In2S3 photocatalyst in practical environmental remediation fields.

  14. In₂S₃/carbon nanofibers/Au ternary synergetic system: hierarchical assembly and enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Zhang, Xin; Shao, Changlu; Li, Xinghua; Lu, Na; Wang, Kexin; Miao, Fujun; Liu, Yichun

    2015-01-01

    In this paper, carbon nanofibers (CNFs) were successfully synthesized by electrospinning technique. Next, Au nanoparticles (NPs) were assembled on the electrospun CNFs through in situ reduction method. By using the obtained Au NPs modified CNFs (CNFs/Au) as hard template, the In2S3/CNFs/Au composites were synthesized through hydrothermal technique. The results showed that the super long one-dimensional (1D) CNFs (about 306 nm in average diameter) were well connected to form a nanofibrous network; and, the Au NPs with 18 nm in average diameter and In2S3 nanosheets with 5-10nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In2S3/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In2S3 and In2S3/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron-hole pairs based on the positive synergetic effect between In2S3, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In2S3/CNFs/Au composites with hierarchical structure possess a strong adsorption ability towards organic dyes, which also contributed to the enhancement of photocatalytic activity. Moreover, the In2S3/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure.

  15. Early Combination of Material Characteristics and Toxicology Is Useful in the Design of Low Toxicity Carbon Nanofiber

    Directory of Open Access Journals (Sweden)

    Tore Syversen

    2012-09-01

    Full Text Available This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product.

  16. Synthesis of carbon nanofibers by CVD as a catalyst support material using atomically ordered Ni3C nanoparticles

    Science.gov (United States)

    Li, Meifeng; Li, Na; Shao, Wei; Zhou, Chungen

    2016-12-01

    Atomically ordered nickel carbide (Ni3C) nanoparticles in polygonal shapes were prepared through the reduction of nickelocene. A novel type of carbon nanofiber (CNF) with twisted conformation was synthesized successfully by catalytic chemical vapor deposition (CCVD) using the obtained Ni3C nanoparticles at a relatively low temperature of 350 °C, which is below the lower limit temperature of 400 °C for the growth of CNFs using metal catalysts. The growth mechanism of the twisted CNFs from Ni3C was freshly derived based on the detailed characterizations. Compared with the growth of CNFs from Ni, graphene layers nucleate at monoatomic step edges and grow in a layer-by-layer manner, while the rotation of the polygonal Ni3C nanoparticles fabricates the twisted conformation during the CNF growth. The electrochemical activity and performance of the twisted CNFs loaded with Pt as electrode catalysts for a polymer electrolyte membrane fuel cell (PEMFC) were measured to be better than those of straight CNFs grown from Ni nanoparticles at 500 °C, since the specific surface conformation helps to make the loaded Pt more homogeneous.

  17. Activated mesoporous carbon nanofibers fabricated using water etching-assisted templating for high-performance electrochemical capacitors.

    Science.gov (United States)

    An, Geon-Hyoung; Koo, Bon-Ryul; Ahn, Hyo-Jin

    2016-03-01

    Activated mesoporous carbon nanofibers (AMCNFs) are synthesized by a sequential process of electrospinning, water etching-assisted templating, and acid treatment. Their morphologies, crystal structures, melting behavior, chemical bonding states, surface properties, and electrochemical performance are investigated for three different polyacrylonitrile (PAN) to polyvinylpyrrolidone (PVP) weight ratios - PAN : PVP = 8 : 2, 7 : 3, and 6 : 4. Compared to other samples, the AMCNFs with an optimum weight ratio of 6 : 4 show the highest specific surface area of 692 m(2) g(-1), a high volume percentage of mesopores of 43.9%, and an increased amount of carboxyl groups (10.5%). This results in a high specific capacitance of 207 F g(-1), a high-rate capability with a capacitance retention of 93%, a high energy density of 24.8-23.1 W h kg(-1), and an excellent cycling durability of up to 3000 cycles. The electrochemical performance improvement can be explained by the combined effect of the high surface area relative to the increased electrical double-layers, the high volume fraction of mesopores relative to shorter diffusion routes and low resistance pathways for ions, and the increased amount of carboxyl groups on the CNF surface relative to enhanced wettability.

  18. COx-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

    Institute of Scientific and Technical Information of China (English)

    Siang-Piao Chai; Sharif Hussein Sharif Zein; Abdul Rahman Mohamed

    2006-01-01

    Direct decomposition of methane was carried out using a fixed-bed reactor at 700 ℃ for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2catalysts (where M=AgO, CoO, CuO, FeO, MnOx and MoO) in methane decomposition was investigated.The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiO2 support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2(w/w) since the highest yield of hydrogen was obtained over this catalyst.

  19. Porous Core-Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction.

    Science.gov (United States)

    Ren, Guangyuan; Lu, Xianyong; Li, Yunan; Zhu, Ying; Dai, Liming; Jiang, Lei

    2016-02-17

    The development of nonprecious-metal-based electrocatalysts with high oxygen reduction reaction (ORR) activity, low cost, and good durability in both alkaline and acidic media is very important for application of full cells. Herein, we developed a facile and economical strategy to obtain porous core-shell Fe3C embedded nitrogen-doped carbon nanofibers (Fe3C@NCNF-X, where X denotes pyrolysis temperature) by electrospinning of polyvinylidene fluoride (PVDF) and FeCl3 mixture, chemical vapor phase polymerization of pyrrole, and followed by pyrolysis of composite nanofibers at high temperatures. Note that the FeCl3 and polypyrrole acts as precursor for Fe3C core and N-doped carbon shell, respectively. Moreover, PVDF not only plays a role as carbon resources, but also provides porous structures due to hydrogen fluoride exposure originated from thermal decomposition of PVDF. The resultant Fe3C@NCNF-X catalysts, particularly Fe3C@NCNF-900, showed efficient electrocatalytic performance for ORR in both alkaline and acidic solutions, which are attributed to the synergistic effect between Fe3C and N-doped carbon as catalytic active sites, and carbon shell protects Fe3C from leaching out. In addition, the Fe3C@NCNF-X catalyst displayed a better long-term stability, free from methanol crossover and CO-poisoning effects than those of Pt/C, which is of great significance for the design and development of advanced electrocatalysts based on nonprecious metals.

  20. Effect of aligned carbon nanotubes on electrical conductivity behaviour in polycarbonate matrix

    Indian Academy of Sciences (India)

    M M Larijani; E J Khamse; Z Asadollahi; M Asadi

    2012-06-01

    This article reports effects of alignment of embedded carbon nanotubes in a polycarbonate polymer matrix under magnetic, direct and alternating current electric fields on the electrical properties of the resulting nanocomposites. Composites consisting of different quantities of carbon nanotubes in a polycarbonate matrix have been prepared using a solution casting technique. The effects of field strength and nanotube concentration on the resulted network structure and conductivity of the composites were studied by in situ optical microscopy, transmission electron microscopy and four-point probe technique. The results showed that the composites prepared in the presence of field had better conductivity than those of as-prepared composites. It was also concluded that the application of alternating current electric field and magnetic field in this system led to the formation of relatively continuing networks while direct current electric field only prevented agglomeration of the carbon nanotubes in the polycarbonate matrix and created relatively uniform distribution of nanotubes in the matrix.

  1. Towards large scale aligned carbon nanotube composites: an industrial safe-by-design and sustainable approach

    Science.gov (United States)

    Boulanger, P.; Belkadi, L.; Descarpentries, J.; Porterat, D.; Hibert, E.; Brouzes, A.; Mille, M.; Patel, S.; Pinault, M.; Reynaud, C.; Mayne-L'Hermite, M.; Decamps, J. M.

    2013-04-01

    We present the main results demonstrating the feasibility of high surface (> A4 format size) semi-industrial fabrication of composites embedding VACNT in organic matrices. The process of growing VACNT exhibits several advantages regarding safety issues: integrating de facto a safe collecting procedure on the substrate, avoiding additional preparation steps and simplifying handling and protection by impregnation into a matrix. The following steps of the overall process: VACNT carpet functionalization, alignment control and impregnation, can be processed on-line in a closed and safe continuous process and lead to dramatically reduced direct nanotube exposure for workers and users. This project opens the route to a continuous, roll-to-roll, safer, cost-effective and green industrial process to manufacture composites with controlled and aligned greener "black" carbon nanotubes.

  2. Synthesis and electrochemical performance of mesoporous SiO{sub 2}–carbon nanofibers composite as anode materials for lithium secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Yura; Choi, Jin-Yeong [Department of Chemistry, Keimyung University (Korea, Republic of); Park, Heai-Ku [Department of Chemical Engineering, Keimyung University (Korea, Republic of); Bae, Jae Young [Department of Chemistry, Keimyung University (Korea, Republic of); Lee, Chang-Seop, E-mail: surfkm@kmu.ac.kr [Department of Chemistry, Keimyung University (Korea, Republic of)

    2016-10-15

    Highlights: • Mesoporous SiO{sub 2}–carbon nanofibers composite synthesized on Ni foam without any binder. • This composite was directly applied as anode material of Li secondary batteries. • Showed the highest initial (2420 mAh/g) and discharging (2092 mAh/g) capacity. • This material achieved a retention rate of 86.4% after 30 cycles. - Abstract: In this study, carbon nanofibers (CNFs) and mesoporous SiO{sub 2}–carbon nanofibers composite were synthesized and applied as the anode materials in lithium secondary batteries. CNFs and mesoporous SiO{sub 2}–CNFs composite were grown via chemical vapor deposition method with iron-copper catalysts. Mesoporous SiO{sub 2} materials were prepared by sol–gel method using tetraethylorthosilicate as the silica source and cetyltrimethylammoniumchloride as the template. Ethylene was used as the carbon source and passes into a quartz reactor of a tube furnace heated to 600 °C, and the temperature was maintained at 600 °C for 10 min to synthesize CNFs and mesoporous SiO{sub 2}–CNFs composite. The electrochemical characteristics of the as-prepared CNFs and mesoporous SiO{sub 2}–CNFs composite as the anode of lithium secondary batteries were investigated using a three-electrode cell. In particular, the mesoporous SiO{sub 2}–CNFs composites synthesized without binder after depositing mesoporous SiO{sub 2} on Ni foam showed the highest charging and discharging capacity and retention rate. The initial capacity (2420 mAh/g) of mesoporous SiO{sub 2}–CNFs composites decreased to 2092 mAh/g after 30 cycles at a retention rate of 86.4%.

  3. Fabrication of carbon nanowires by pyrolysis of aqueous solution of sugar within asbestos nanofibers

    Science.gov (United States)

    Butko, V. Yu.; Fokin, A. V.; Nevedomskii, V. N.; Kumzerov, Yu. A.

    2015-05-01

    Carbon nanowires have been fabricated by pyrolysis of an aqueous solution of sugar in nanochannels of asbestos fibers. Electron microscopy demonstrates that the diameter of these nanochannels corresponds to the diameter of the thinnest of the carbon nanowires obtained. Some of these nanowires have a graphite crystal lattice and internal pores. After asbestos is etched out, the carbon nanowires can retain the original shape of the asbestos fibers. Heating in an inert atmosphere reduces the electrical resistivity of the carbon nanowires to ˜0.035 Ω cm.

  4. Third order optical nonlinear studies on highly conducting vertically aligned carbon nanoflakes

    Science.gov (United States)

    Singh, Mukesh; Kumar, Indrajeet; Khare, Alika; Agarwal, Pratima

    2016-12-01

    Third order optical nonlinearity of carbon nanoflakes were studied by modified single beam closed aperture Z-scan technique using a continuous wave He-Ne laser at 632.8 nm. Thin films of vertically aligned carbon nanoflakes were synthesized on corning glass substrate at substrate temperature of 400 °C by hot filament chemical vapor deposition. Films were characterized by scanning electron microscope and atomic force microscopy which confirmed that carbon nanoflakes were vertically aligned on the substrate. Temperature dependent electrical conductivity measurements in temperature range of 300-480 K under high vacuum (˜10-5 mbar) showed that conductivity of the films was increased almost linearly with increasing temperature with a weak temperature dependence. The negative temperature coefficient of resistance indicates semiconducting behavior of the films. Nonlinear refractive index coefficient (n 2) of the films was found to be of the order of 10-5 cm2 W-1, which can be important for the applications in the field of nonlinear photonics.

  5. Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays.

    Science.gov (United States)

    Stano, Kelly L; Carroll, Murphy; Padbury, Richard; McCord, Marian; Jur, Jesse S; Bradford, Philip D

    2014-11-12

    Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.

  6. Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures

    Science.gov (United States)

    Kaul, Anupama B.; Megerian, Krikor G.; Von Allmen, Paul A.; Baron, Richard L.

    2010-01-01

    Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are

  7. Electrospun Nanofibers for Neural and Tissue Engineering

    Science.gov (United States)

    Xia, Younan

    2009-03-01

    Electrospinning has been exploited for almost one century to process polymers and other materials into nanofibers with controllable compositions, diameters, porosities, and porous structures for a variety of applications. Owing to its small size, high porosity, and large surface area, a nonwoven mat of electrospun nanofibers can serve as an ideal scaffold to mimic the extra cellular matrix for cell attachment and nutrient transportation. The nanofiber itself can also be functionalized through encapsulation or attachment of bioactive species such as extracellular matrix proteins, enzymes, and growth factors. In addition, the nanofibers can be further assembled into a variety of arrays or architectures by manipulating their alignment, stacking, or folding. All these attributes make electrospinning a powerful tool for generating nanostructured materials for a range of biomedical applications that include controlled release, drug delivery, and tissue engineering. This talk will focus on the use of electrospun nanofibers as scaffolds for neural and bone tissue engineering.

  8. Modeling and experimental study of resistive switching in vertically aligned carbon nanotubes

    Science.gov (United States)

    Ageev, O. A.; Blinov, Yu F.; Ilina, M. V.; Ilin, O. I.; Smirnov, V. A.

    2016-08-01

    Model of the resistive switching in vertically aligned carbon nanotube (VA CNT) taking into account the processes of deformation, polarization and piezoelectric charge accumulation have been developed. Origin of hysteresis in VA CNT-based structure is described. Based on modeling results the VACNTs-based structure has been created. The ration resistance of high-resistance to low-resistance states of the VACNTs-based structure amounts 48. The correlation the modeling results with experimental studies is shown. The results can be used in the development nanoelectronics devices based on VA CNTs, including the nonvolatile resistive random-access memory.

  9. Flow Field Induced Steady Alignment of Oxidized Multi-walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ai Zhong XU; Ming Shu YANG; Qiang WU; Xiao Ming HU; Lei JIANG

    2005-01-01

    The steady ordered micro-ribbons of oxidized multi-walled carbon nanotubes (MWNTs)were obtained through micro-aperture PTFE membrane by vacuum filtration. After treatment by mixture of concentrated nitric acid and sulfuric acid, the surface functional groups modified MWNTs can be easily dispersed to form a homogeneous suspension. It is found that the steady micro-ribbons existed in the films obtained by vacuum filtration of the suspension. The filtration formed steady flow field and induced steady alignment of oxidized MWNTs. The chemical treatment of MWNTs forming strong interaction between MWNTs is necessity to keep steady of the micro-ribbons microstructure.

  10. High-rate capability silicon decorated vertically aligned carbon nanotubes for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Gohier, Aurelien; Kim, Ki-Hwan; Maurice, Jean-Luc; Cojocaru, Costel Sorin [Laboratoire de Physique des Interfaces et des Couches Minces, LPICM, Ecole Polytechnique, route de Saclay, 91128 Palaiseau Cedex (France); Laik, Barbara; Pereira-Ramos, Jean-Pierre [Institut de Chimie et des Materiaux Paris-Est, ICMPE/GESMAT, UMR 7182 CNRS-UPEC, 2 rue Henri Dunant, 94320 Thiais (France); Van, Pierre Tran [Renault SAS, DREAM/DETA/SEE, 1, avenue du Golf, 78288 Guyancourt (France)

    2012-05-15

    The concept of a hybrid nanostructured collector made of thin vertically aligned carbon nanotubes (CNTs) decorated with Si nanoparticles provides high power density anodes in lithium-ion batteries. An impressive rate capability is achieved due to the efficient electronic conduction of CNTs combined with well defined electroactive Si nanoparticles: capacities of 3000 mAh g{sup -1} at 1.3C and 800 mAh g{sup -1} at 15C are achieved. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Thermal conductivity of vertically aligned carbon nanotube arrays: Growth conditions and tube inhomogeneity

    Science.gov (United States)

    Bauer, Matthew L.; Pham, Quang N.; Saltonstall, Christopher B.; Norris, Pamela M.

    2014-10-01

    The thermal conductivity of vertically aligned carbon nanotube arrays (VACNTAs) grown on silicon dioxide substrates via chemical vapor deposition is measured using a 3ω technique. For each sample, the VACNTA layer and substrate are pressed to a heating line at varying pressures to extract the sample's thermophysical properties. The nanotubes' structure is observed via transmission electron microscopy and Raman spectroscopy. The presence of hydrogen and water vapor in the fabrication process is tuned to observe the effect on measured thermal properties. The presence of iron catalyst particles within the individual nanotubes prevents the array from achieving the overall thermal conductivity anticipated based on reported measurements of individual nanotubes and the packing density.

  12. Cyclohexane triggers staged growth of pure and vertically aligned single wall carbon nanotubes

    Science.gov (United States)

    Ayala, P.; Grüneis, A.; Grimm, D.; Kramberger, C.; Engelhard, R.; Rümmeli, M.; Schumann, J.; Kaltofen, R.; Büchner, B.; Schaman, C.; Kuzmany, H.; Gemming, T.; Barreiro, A.; Pichler, T.

    2008-03-01

    An innovative staged chemical vapor deposition (SCVD) approach providing flexible control over the feedstock type during single wall carbon nanotube (SWNTs) growth is proposed. The efficiency of staged growth by means of a cyclohexane/methane system using thin film catalysts is here illustrated. The mechanism involves the nucleation stage efficiently triggered by cyclohexane, followed by methane assisting a growth stage yielding high purity SWNTs vertically aligned with lengths of several hundred μm. In addition, SCVD also facilitates catalyst free SWNT detachment enabling repeated growth.

  13. Highly aligned carbon nanotube forests coated by superconducting NbC.

    Science.gov (United States)

    Zou, G F; Luo, H M; Baily, S; Zhang, Y Y; Haberkorn, N F; Xiong, J; Bauer, E; McCleskey, T M; Burrell, A K; Civale, L; Zhu, Y T; Macmanus-Driscoll, J L; Jia, Q X

    2011-08-16

    The formation of carbon nanotube and superconductor composites makes it possible to produce new and/or improved functionalities that the individual material does not possess. Here we show that coating carbon nanotube forests with superconducting niobium carbide (NbC) does not destroy the microstructure of the nanotubes. NbC also shows much improved superconducting properties such as a higher irreversibility and upper critical field. An upper critical field value of ~5 T at 4.2 K is much greater than the 1.7 T reported in the literature for pure bulk NbC. Furthermore, the aligned carbon nanotubes induce anisotropy in the upper critical field, with a higher upper critical field occurring when the magnetic field is parallel to the carbon nanotube growth direction. These results suggest that highly oriented carbon nanotubes embedded in superconducting NbC matrix can function as defects and effectively enhance the superconducting properties of the NbC.

  14. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

    Science.gov (United States)

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g-1, far exceeding spider dragline silk (165 J g-1) and Kevlar (78 J g-1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

  15. Porosimetry and packing morphology of vertically aligned carbon nanotube arrays via impedance spectroscopy

    Science.gov (United States)

    Mutha, Heena K.; Lu, Yuan; Stein, Itai Y.; Cho, H. Jeremy; Suss, Matthew E.; Laoui, Tahar; Thompson, Carl V.; Wardle, Brian L.; Wang, Evelyn N.

    2017-02-01

    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. In this work, we combined electrochemical impedance spectroscopy (EIS) with capacitance measurements and porous electrode theory to conduct in situ porosimetry of vertically aligned carbon nanotube (VA-CNT) forests non-destructively. We utilized the EIS measurements with a pore size distribution model to quantify the average and dispersion of inter-CNT spacing (Γ), stochastically, in carpets that were mechanically densified from 1.7× {10}10 tubes cm-2 to 4.5× {10}11 tubes cm-2. Our analysis predicts that the inter-CNT spacing ranges from over 100 ± 50 nm in sparse carpets to sub 10 ± 5 nm in packed carpets. Our results suggest that waviness of CNTs leads to variations in the inter-CNT spacing, which can be significant in sparse carpets. This methodology can be used to predict the performance of many nanostructured devices, including supercapacitors, batteries, solar cells, and semiconductor electronics.

  16. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  17. Integrated fast assembly of free-standing lithium titanate/carbon nanotube/cellulose nanofiber hybrid network film as flexible paper-electrode for lithium-ion batteries.

    Science.gov (United States)

    Cao, Shaomei; Feng, Xin; Song, Yuanyuan; Xue, Xin; Liu, Hongjiang; Miao, Miao; Fang, Jianhui; Shi, Liyi

    2015-05-27

    A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics.

  18. Well-aligned carbon nanotube array membrane and its field emission properties

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ensembles of aligned and monodispersed carbon nanotubes (CNTs)can be prepared by templating method which involves fabrication of porous anodic aluminum oxide (AAO) template, control of catalytic iron particle size and chemical vapor deposition of carbon in the cylindrical pores of AAO. Here we show that template-synthesized CNTs can be fabricated as well-aligned nanoporous CNTs membrane, which can be directly used as an electron field emitter. A low threshold electric field of 2-4 V/μm and maximum emission current density of ~12 mA/cm2 are observed. The results also show that the electron emission current is a function of the applied electrical field and the Fowler-Nordheim (F-N) plot almost follows a linear relationship which indicates a Fowler-Nordheim tunneling mechanism, and the field enhancement factor estimated is about 1100-7500. The simple and convenient approach should be significant for the development of nanotube devices integrated into field emission displays (FEDs) technology.

  19. Photopolymerization of Diacetylene on Aligned Multiwall Carbon Nanotube Microfibers for High-Performance Energy Devices.

    Science.gov (United States)

    Ulaganathan, Mani; Hansen, Reinack Varghese; Drayton, Nateisha; Hingorani, Hardik; Kutty, R Govindan; Joshi, Hrishikesh; Sreejith, Sivaramapanicker; Liu, Zheng; Yang, Jinglei; Zhao, Yanli

    2016-12-07

    Linear two-dimensional materials have recently attracted an intense interest for supercapacitors because of their potential uses as electrodes in next-generation wearable electronics. However, enhancing the electrochemical properties of these materials without complicated structural modifications remains a challenge. Herein, we present the preparation of a hybrid electrode system via polydiacetylene (PDA) cloaking on the surface of aligned multiwall carbon nanotubes (MWCNTs) through self-assembly based in situ photopolymerization. This strategy eliminates the need for initiators and binders that hinder electrochemical performance in conventional conducting polymer based composite electrodes. As noncovalent PDA cloaking did not alter the chemical structure of MWCNTs, high inherent conductivity from sp(2) hybridized carbon was preserved. The resulting hybrid microfiber (MWCNT@PDA) exhibited a significant increase in specific capacitance (1111 F g(-1)) when compared to bare MWCNTs (500 F g(-1)) and PDA (666.7 F g(-1)) in a voltage window of 0-1.2 V at a current density of 3 A g(-1) in 0.5 M K2SO4 electrolyte. The specific capacitance was retained (ca. 95%) after 7000 charge/discharge cycles. The present results suggest that aligned MWCNTs cloaked with conjugated polymers could meet the demands for future flexible electronics.

  20. Metal-free N-doped carbon nanofibers as an efficient catalyst for oxygen reduction reactions in alkaline and acid media

    Science.gov (United States)

    Li, Ruchun; Shao, Xiaofeng; Li, Shuoshuo; Cheng, Pengpeng; Hu, Zhaoxia; Yuan, Dingsheng

    2016-12-01

    The development of metal-free catalysts to replace the use of Pt has played an important role in relation to its application to fuel cells. We report N-doped carbon nanofibers as the catalyst of an oxygen reduction reaction, which were synthesized via carbonizing bacterial cellulose-polypyrrole composites. The as-prepared material exhibited remarkable catalytic activity toward the oxygen reduction reaction with comparable onset potential and the ability to limit the current density of commercial Pt/C catalysts in both alkaline and acid media due to the unique porous three-dimensional network structure and the doped nitrogen atoms. The effect of N functionalities on catalytic behavior was systematically investigated. The results demonstrated that pyridinic-N was the dominating factor for catalytic performance toward the oxygen reduction reaction. Additionally, N-doped carbon nanofibers also demonstrated excellent cycling stability (93.2% and 89.4% retention of current density after chronoamperometry 20 000 s in alkaline and media, respectively), obviously superior to Pt/C.

  1. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    Directory of Open Access Journals (Sweden)

    Tomohiro Iwasaki

    2016-06-01

    Full Text Available Abstract To synthesize nitrogen-doped carbon nanofibers (N-CNFs at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate and then calcined at 1073 K for 1 h in oxidative (air, reductive (hydrogen-containing argon, or inert (pure argon atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  2. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    Science.gov (United States)

    Iwasaki, Tomohiro; Makino, Yuri; Fukukawa, Makoto; Nakamura, Hideya; Watano, Satoru

    2016-11-01

    To synthesize nitrogen-doped carbon nanofibers (N-CNFs) at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide) supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD) process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate) and then calcined at 1073 K for 1 h in oxidative (air), reductive (hydrogen-containing argon), or inert (pure argon) atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  3. Vertically aligned carbon nanotubes/carbon fiber paper composite to support Pt nanoparticles for direct methanol fuel cell application

    Science.gov (United States)

    Zhang, Jing; Yi, Xi-bin; Liu, Shuo; Fan, Hui-Li; Ju, Wei; Wang, Qi-Chun; Ma, Jie

    2017-03-01

    Vertically aligned carbon nanotubes (VACNTs) grown on carbon fiber paper (CFP) by plasma enhanced chemical vapor deposition is introduced as a catalyst support material for direct methanol fuel cells (DMFCs). Well dispersed Pt nanoparticles on VACNTs surface are prepared by impregnation-reduction method. The VACNTs on CFP possess well-maintained alignment, large surface area and good electrical conductivity, which leading to the formation of Pt particles with a smaller size and enhance the Pt utilization rate. The structure and nature of resulting Pt/VACNTs/CFP catalysts for methanol oxidation are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). With the aid of VACNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway, which leads to enhance the catalytic activity and Pt utilization rate. Compared with the Pt/XC-72/CFP electrode, the electrochemical measurements results display that the Pt/VACNTs/CFP catalyst shows much higher electrocatalytic activity and better stability for methanol oxidation. In addition, the oxidation current from 200 to 1200 s decayed more slowly for the Pt/VACNTs/CFP than that of the Pt/XC-72/CFP catalysts, indicating less accumulation of adsorbed CO species. All those results imply that the Pt/VACNTs/CFP has a great potential for applications in DMFCs.

  4. Adsorption behavior of perfluorinated sulfonic acid ionomer on highly graphitized carbon nanofibers and their thermal stabilities

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Borghei, Maryam; Dhiman, Rajnish

    2014-01-01

    of decreasing hydrophobicity. This is indicated by the initial decrease and then increase in the value of Keq. with the increasing strength of the acid treatment. The corresponding carbon - ionomer composite also showed varying thermal stability depending on Nafion orientation. The specific maximum surface...... isotherm), the ionomer has varying affinities for CNFs (Keq. = between 5 and 22) as compared to Vulcan (Keq. = 18), depending on surface treatments. However, the interactions are most likely governed by different adsorption mechanisms depending on hydrophilicity / hydrophobicity of the adsorbent carbon...

  5. A Low Cost Carbon Nanofiber Based Spiral Inductor: Inference and Implementation

    Directory of Open Access Journals (Sweden)

    John Wiselin

    2014-01-01

    Full Text Available This paper investigates the possibilities of using carbon fiber as an inductor material by analyzing its inductive properties. Various shapes such as rectangular, spiral, helical, and cylindrical line structures have been simulated under various constraints using simulation software. Hardware implementations were also tested and both simulation and hardware results show that carbon fibers have the potential to replace copper inductor lines. The implemented spiral inductor produced a quality factor of 40 while producing an inductance of 4 nH at 1.2 GHz frequency.

  6. Liquid-Phase Deposition of Aligned Carbon Nanotubes Using Cobalt Catalyst

    Science.gov (United States)

    Nishitani-Gamo, Mikka; Shibasaki, Takeshi; Gamo, Hidenori; Nakagawa, Kiyoharu; Ando, Toshihiro

    2007-09-01

    We have recently developed a novel catalytic method for synthesizing a wide variety of carbon nanomaterials in the organic liquid. The method enabled us to realize a simple, rapid, and high-purity growth of carbon nanotubes (CNTs) in alcohol liquids. In this study, cobalt (Co) was used as a catalyst metal. In order to control the structure of carbon nanomaterials, we investigated the relationship between the growth conditions and the grown materials. Scanning electron microscopy (SEM) observation revealed that the morphology of the grown carbon nanomaterials strongly depended on the reaction temperature. Under the reaction temperature in the range from 873 to 973 K, fibriform deposits were mainly obtained. Transmission electron microscopy (TEM) revealed that the fibriform deposits were CNTs. The amount of the supported Co catalyst affected the fine tubular structure of the CNTs. We found that the existence of the reaction temperature of 873 K during the reaction time was essential for growing a fibriform structure in this study. The longer duration time for the reaction temperature of 1127 K resulted in a higher crystal quality for CNTs. We also demonstrated that the Co catalyst thermal oxidation at 1173 K resulted in the growth of aligned CNTs with the higher density.

  7. Nanofibers of Ca2Fe2O5: A novel material for aqueous supercapacitor

    Science.gov (United States)

    Sundriyal, Sandeep Kumar; Bhagwan, Jai; Sharma, Yogesh

    2016-05-01

    Porous, aligned and high aspect ratio nanofibers of Ca2Fe2O5 (CFO) have been fabricated by varying various system and process parameter of electrospinning technique for the first time. CFO nanofibers are further characterized by XRD, FESEM and BET surface area. The diameter of as-spun nanofibers of CFO was found to be polymer concentration dependent. Heating profile is found to be responsible for alignment of CFO nanofibers. For the first time, novel CFO nanofibers were subjected to cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) cycling to investigate its energy storage performance as electrode material for aqueous supercapacitor, and accordingly preliminary results are discussed.

  8. The production of carbon nanofibers and thin films on palladium catalysts from ethylene oxygen mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Doorn, Stephen [Los Alamos National Laboratory; Atwater, Mark [UNM MECH.ENG.; Leseman, Zayd [UNM MECH.ENG.; Luhrs, Claudia C [UNM ENG.MECH; Diez, Yolanda F [SPAIN; Diaz, Angel M [SPAIN

    2009-01-01

    The characteristics of carbonaceous materials deposited in fuel rich ethylene-oxygen mixtures on three types of palladium: foil, sputtered film, and nanopowder, are reported. It was found that the form of palladium has a dramatic influence on the morphology of the deposited carbon. In particular, on sputtered film and powder, tight 'weaves' of sub-micron filaments formed quickly. In contrast, on foils under identical conditions, the dominant morphology is carbon thin films with basal planes oriented parallel to the substrate surface. Temperature, gas flow rate, reactant flow ratio (C2H4:02), and residence time (position) were found to influence both growth rate and type for all three forms of Pd. X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed oxidation, and Raman spectroscopy were used to assess the crystallinity of the as-deposited carbon, and it was determined that transmission electron microscopy and x-ray diffraction were the most reliable methods for determining crystallinity. The dependence of growth on reactor position, and the fact that no growth was observed in the absence of oxygen support the postulate that the carbon deposition proceeds by combustion generated radical species.

  9. Mechanisms for catalytic carbon nanofiber growth studied by ab initio density functional theory calculations

    DEFF Research Database (Denmark)

    Abild-Pedersen, Frank; Nørskov, Jens Kehlet; Rostrup-Nielsen, Jens;

    2006-01-01

    Mechanisms and energetics of graphene growth catalyzed by nickel nanoclusters were studied using ab initio density functional theory calculations. It is demonstrated that nickel step-edge sites act as the preferential growth centers for graphene layers on the nickel surface. Carbon is transported...

  10. Flame Synthesis of Single- and Multi-Walled Carbon Nanotubes and Nanofibers

    Science.gov (United States)

    VanderWal, R. L.; Ticich, Thomas M.

    2001-01-01

    Metal-catalyzed carbon nanotubes are highly sought for a diverse range of applications that include nanoelectronics, battery electrode material, catalysis, hydrogen storage media and reinforcing agents in polymer composites. These latter applications will require vast quantities of nanotubes at competitive prices to be economically feasible. Moreover, reinforcing applications may not require ultrahigh purity nanotubes. Indeed, functionalization of nanotubes to facilitate interfacial bonding within composites will naturally introduce defects into the tube walls, lessening their tensile strength. Current methods of aerosol synthesis of carbon nanotubes include laser ablation of composite targets of carbon and catalyst metal within high temperature furnaces and decomposition of a organometallics in hydrocarbons mixtures within a tube furnace. Common to each approach is the generation of particles in the presence of the reactive hydrocarbon species at elevated temperatures. In the laser-ablation approach, the situation is even more dynamic in that particles and nanotubes are borne during the transient cooling phase of the laser-induced plasma for which the temperature far exceeds that of the surrounding hot gases within the furnace process tube. A shared limitation is that more efficient methods of nanoparticle synthesis are not readily incorporated into these approaches. In contrast, combustion can quite naturally create nanomaterials such as carbon black. Flame synthesis is well known for its commercial scalability and energy efficiency. However, flames do present a complex chemical environment with steep gradients in temperature and species concentrations. Moreover, reaction times are limited within buoyant driven flows to tens of milliseconds. Therein microgravity can greatly lessen temperature and spatial gradients while allowing independent control of flame residence times. In preparation for defining the microgravity experiments, the work presented here focuses

  11. Electrical, Mechanical, and Morphological Characterization of Carbon Nanotube filled Polymeric Nanofibers

    Science.gov (United States)

    Gorga, Russell; Clarke, Laura; McCullen, Seth; Ojha, Satyajeet; Roberts, Wesley

    2006-03-01

    This work focuses on the inclusion of conductive nanotubes into polymeric matrices with the end goal of creating conductive nanocomposites. This investigation has been carried out by uniform dispersion of multi-walled carbon nanotubes in aqueous solutions of polyvinyl alcohol (PVA) and polyethylene oxide (PEO), which are inherently nonconductive polymers. To fabricate these structures we are using the electrospinning process encompassing an array of collection methods including parallel bars and a static plate. Carbon nanotubes are known to have excellent electrical conductivity and mechanical properties. This investigation shows that the inclusion of carbon nanotubes increases the electronic conduction in these polymers and enhances the mechanical properties of the composites. Dispersion of these nanotubes is the key factor in this process; gum Arabic and surfactants have been utilized for the dispersion of these nanotubes. Conductivity measurements have been carried out by two point probe method and by performing sensitive current and conductance measurements with a femtoammeter. Further morphological characterization has been performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).^1 Department of Textile Engineering, Chemistry, and Science ^2 Department of Physics

  12. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

    Science.gov (United States)

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E; Liu, Tianxi

    2016-01-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications. PMID:27511271

  13. Characterization of Mechanical Properties at the Micro/Nano Scale: Stiction Failure of MEMS, High-Frequency Michelson Interferometry and Carbon NanoFibers

    Science.gov (United States)

    Kheyraddini Mousavi, Arash

    Different forces scale differently with decreasing length scales. Van der Waals and surface tension are generally ignored at the macro scale, but can become dominant at the micro and nano scales. This fact, combined with the considerable compliance and large surface areas of micro and nano devices, can leads to adhesion in MicroElectroMechanical Systems (MEMS) and NanoElectroMechanical Systems (NEMS) - a.k.a. stiction-failure. The adhesive forces between MEMS devices leading to stiction failure are characterized in this dissertation analytically and experimentally. Specifically, the adhesion energy of poly-Si μcantilevers are determined experimentally through Mode II and mixed Mode I&II crack propagation experiments. Furthermore, the description of a high-frequency Michelson Interferometer is discussed for imaging of crack propagation of the μcantilevers with their substrate at the nano-scale and harmonic imaging of MEMS/NEMS. Van der Waals forces are also responsible for the adhesion in nonwoven carbon nanofiber networks. Experimental and modeling results are presented for the mechanical and electrical properties of nonwoven (random entanglements) of carbon nanofibers under relatively low and high-loads, both in tensions and compression. It was also observed that the structural integrity of these networks is controlled by mechanical entanglement and flexural rigidity of individual fibers as well as Hertzian forces at the fiber/fiber interface.

  14. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

    Science.gov (United States)

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E.; Liu, Tianxi

    2016-08-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications.

  15. Integration and characterization of aligned carbon nanotubes on metal/silicon substrates and effects of water

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yong; Li Ruying; Liu Hao [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Merel, Philippe; Desilets, Sylvain [Defence Research and Development Canada- Valcartier, 2459 Boulevard Pie-XI nord, Quebec, QC G3J 1X5 (Canada)

    2009-02-15

    We report here a facile way to grow aligned multi-walled carbon nanotubes (MWCNTs) on various metal (e.g. gold, tungsten, vanadium and copper)/silicon electrically conductive substrates by aerosol-assisted chemical vapor deposition (AACVD). Without using any buffer layers, integration of high quality MWCNTs to the conductive substrates has been achieved by introducing appropriate amount of water vapor into the growth system. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) determination indicate tidy morphology and narrow diameter distribution of the nanotubes as well as promising growth rate suitable for industrial applications. Raman spectra analysis illustrates that the structural order and purity of the nanotubes are significantly improved in the presence of water vapor. The growth mechanism of the nanotubes has been discussed. It is believed that water vapor plays a key role in the catalyst-substrate interaction and nucleation of the carbon nanotubes on the conductive substrates. This synthesis approach is expected to be extended to other catalyst-conductive substrate systems and provide some new insight in the direct integration of carbon nanotubes onto conductive substrates, which promises great potential for applications in electrical interconnects, contacts for field emitters, and other electronic nanodevices.

  16. Influence of contact height on the performance of vertically aligned carbon nanotube field-effect transistors

    KAUST Repository

    Li, Jingqi

    2013-01-01

    Vertically aligned carbon nanotube field-effect transistors (CNTFETs) have been experimentally demonstrated (J. Li et al., Carbon, 2012, 50, 4628-4632). The source and drain contact heights in vertical CNTFETs could be much higher than in flat CNTFETs if the fabrication process is not optimized. To understand the impact of contact height on transistor performance, we use a semi-classical method to calculate the characteristics of CNTFETs with different contact heights. The results show that the drain current decreases with increasing contact height and saturates at a value governed by the thickness of the oxide. The current reduction caused by the increased contact height becomes more significant when the gate oxide is thicker. The higher the drain voltage, the larger the current reduction. It becomes even worse when the band gap of the carbon nanotube is larger. The current can differ by a factor of more than five between the CNTEFTs with low and high contact heights when the oxide thickness is 50 nm. In addition, the influence of the contact height is limited by the channel length. The contact height plays a minor role when the channel length is less than 100 nm. © 2013 The Royal Society of Chemistry.

  17. Thermal property tuning in aligned carbon nanotube films and random entangled carbon nanotube films by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing [Department of Materials Science and Engineering, Texas A& M University, College Station, Texas 77843 (United States); Chen, Di; Wang, Xuemei [Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States); Bykova, Julia S.; Zakhidov, Anvar A. [The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080 (United States); Shao, Lin, E-mail: lshao@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, Texas 77843 (United States); Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States)

    2015-10-12

    Ion irradiation effects on thermal property changes are compared between aligned carbon nanotube (A-CNT) films and randomly entangled carbon nanotube (R-CNT) films. After H, C, and Fe ion irradiation, a focusing ion beam with sub-mm diameter is used as a heating source, and an infrared signal is recorded to extract thermal conductivity. Ion irradiation decreases thermal conductivity of A-CNT films, but increases that of R-CNT films. We explain the opposite trends by the fact that neighboring CNT bundles are loosely bonded in A-CNT films, which makes it difficult to create inter-tube linkage/bonding upon ion irradiation. In a comparison, in R-CNT films, which have dense tube networking, carbon displacements are easily trapped between touching tubes and act as inter-tube linkage to promote off-axial phonon transport. The enhancement overcomes the phonon transport loss due to phonon-defect scattering along the axial direction. A model is established to explain the dependence of thermal conductivity changes on ion irradiation parameters including ion species, energies, and current.

  18. Vertically aligned carbon nanotube-sheathed carbon fibers as pristine microelectrodes for selective monitoring of ascorbate in vivo.

    Science.gov (United States)

    Xiang, Ling; Yu, Ping; Hao, Jie; Zhang, Meining; Zhu, Lin; Dai, Liming; Mao, Lanqun

    2014-04-15

    Using as-synthesized vertically aligned carbon nanotube-sheathed carbon fibers (VACNT-CFs) as microelectrodes without any postsynthesis functionalization, we have developed in this study a new method for in vivo monitoring of ascorbate with high selectivity and reproducibility. The VACNT-CFs are formed via pyrolysis of iron phthalocyanine (FePc) on the carbon fiber support. After electrochemical pretreatment in 1.0 M NaOH solution, the pristine VACNT-CF microelectrodes exhibit typical microelectrode behavior with fast electron transfer kinetics for electrochemical oxidation of ascorbate and are useful for selective ascorbate monitoring even with other electroactive species (e.g., dopamine, uric acid, and 5-hydroxytryptamine) coexisting in rat brain. Pristine VACNT-CFs are further demonstrated to be a reliable and stable microelectrode for in vivo recording of the dynamic increase of ascorbate evoked by intracerebral infusion of glutamate. Use of a pristine VACNT-CF microelectrode can effectively avoid any manual electrode modification and is free from person-to-person and/or electrode-to-electrode deviations intrinsically associated with conventional CF electrode fabrication, which often involves electrode surface modification with randomly distributed CNTs or other pretreatments, and hence allows easy fabrication of highly selective, reproducible, and stable microelectrodes even by nonelectrochemists. Thus, this study offers a new and reliable platform for in vivo monitoring of neurochemicals (e.g., ascorbate) to largely facilitate future studies on the neurochemical processes involved in various physiological events.

  19. Alignment controlled growth of single-walled carbon nanotubes on quartz substrates.

    Science.gov (United States)

    Xiao, Jianliang; Dunham, Simon; Liu, Ping; Zhang, Yongwei; Kocabas, Coskun; Moh, Lionel; Huang, Yonggang; Hwang, Keh-Chih; Lu, Chun; Huang, Wei; Rogers, John A

    2009-12-01

    Single-walled carbon nanotubes (SWNTs) possess extraordinary electrical properties, with many possible applications in electronics. Dense, horizontally aligned arrays of linearly configured SWNTs represent perhaps the most attractive and scalable way to implement this class of nanomaterial in practical systems. Recent work shows that templated growth of tubes on certain crystalline substrates yields arrays with the necessary levels of perfection, as demonstrated by the formation of devices and full systems on quartz. This paper examines advanced implementations of this process on crystalline quartz substrates with different orientations, to yield strategies for forming diverse, but well-defined horizontal configurations of SWNTs. Combined experimental and theoretical studies indicate that angle-dependent van der Waals interactions can account for nearly all aspects of alignment on quartz with X, Y, Z, and ST cuts, as well as quartz with disordered surface layers. These findings provide important insights into methods for guided growth of SWNTs, and possibly other classes of nanomaterials, for applications in electronics, sensing, photodetection, light emission, and other areas.

  20. Horizontally aligned single walled carbon nanotube arrays on quartz for electrochemical biosensing

    Science.gov (United States)

    Yang, Yuehai; Wang, Xuewen; Li, Wenzhi; He, Jin

    2014-03-01

    We have fabricated and characterized a simple and high performance electrochemical sensor using horizontally aligned single walled carbon nanotube arrays on transparent single crystal quartz substrates grown by chemical vapor deposition. The electrochemical activities of redox probes Fe(CN)63- / 4 - , Ru(NH3) 6 3 + and protein cytochrome c on these pristine SWCNT thin films have been studied. Because the surface coverage of CNTs is extremely low and aligned, the shape of cyclic voltammograms of these molecules in stationary solution is strongly affected by the mass transport rate of molecules and the interactions between molecules and the SWCNT surface. We also studied the electrochemical flow sensing capability of the device for detecting neurotransmitter dopamine at physiological conditions with the presence of Bovine serum albumin. Good sensitivity, fast response, high stability and anti-fouling capability are observed. Therefore, this device shows great potential for sensing applications in complex solution. This work was supported by a start-up fund (J. H.), NSF (CMMI-1334417) and the American Chemical Society under grant PRF #51766-ND10.