WorldWideScience

Sample records for aligned carbon nanofiber

  1. 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

  2. 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.

  3. 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.

  4. Enhanced catalytic activity of polyethylenedioxythiophene towards tri-iodide reduction in DSSCs via 1-dimensional alignment using hollow carbon nanofibers

    Science.gov (United States)

    Anothumakkool, Bihag; Game, Onkar; Bhange, Siddheshwar N.; Kumari, Tanya; Ogale, Satishchandra B.; Kurungot, Sreekumar

    2014-08-01

    Here, we report a highly conducting 1-dimensionally (1-D) aligned polyethylenedioxythiophene (PEDOT) along the inner and outer surfaces of a hollow carbon nanofiber (CNF) and its application as a counter electrode in a dye sensitized solar cell (DSSC). The hybrid material (CP-25) displays a conversion efficiency of 7.16% compared to 7.30% for the standard Pt counter electrode, 4.48% for bulk PEDOT and 5.56% for CNF. The enhanced conversion efficiency of CP-25 is attributed to the accomplishment of high conductivity and surface area of PEDOT through the 1-D alignment compared to its bulk counterpart. Reduced charge transfer resistance and high conductivity of CP-25 could be proven by cyclic voltammetry, impedance analysis and Tafel experiments. Further, through a long-term stability test involving efficiency profiling for 20 days, it is observed that CP-25 possesses excellent durability compared to the bulk PEDOT.Here, we report a highly conducting 1-dimensionally (1-D) aligned polyethylenedioxythiophene (PEDOT) along the inner and outer surfaces of a hollow carbon nanofiber (CNF) and its application as a counter electrode in a dye sensitized solar cell (DSSC). The hybrid material (CP-25) displays a conversion efficiency of 7.16% compared to 7.30% for the standard Pt counter electrode, 4.48% for bulk PEDOT and 5.56% for CNF. The enhanced conversion efficiency of CP-25 is attributed to the accomplishment of high conductivity and surface area of PEDOT through the 1-D alignment compared to its bulk counterpart. Reduced charge transfer resistance and high conductivity of CP-25 could be proven by cyclic voltammetry, impedance analysis and Tafel experiments. Further, through a long-term stability test involving efficiency profiling for 20 days, it is observed that CP-25 possesses excellent durability compared to the bulk PEDOT. Electronic supplementary information (ESI) available: Experimental methods and supporting figures. See DOI: 10.1039/c4nr00717d

  5. Integrated on-chip solid state capacitor based on vertically aligned carbon nanofibers, grown using a CMOS temperature compatible process

    Science.gov (United States)

    Saleem, Amin M.; Andersson, Rickard; Desmaris, Vincent; Enoksson, Peter

    2018-01-01

    Complete miniaturized on-chip integrated solid-state capacitors have been fabricated based on conformal coating of vertically aligned carbon nanofibers (VACNFs), using a CMOS temperature compatible microfabrication processes. The 5 μm long VACNFs, operating as electrode, are grown on a silicon substrate and conformally coated by aluminum oxide dielectric using atomic layer deposition (ALD) technique. The areal (footprint) capacitance density value of 11-15 nF/mm2 is realized with high reproducibility. The CMOS temperature compatible microfabrication, ultra-low profile (less than 7 μm thickness) and high capacitance density would enables direct integration of micro energy storage devices on the active CMOS chip, multi-chip package and passives on silicon or glass interposer. A model is developed to calculate the surface area of VACNFs and the effective capacitance from the devices. It is thereby shown that 71% of surface area of the VACNFs has contributed to the measured capacitance, and by using the entire area the capacitance can potentially be increased.

  6. Investigation of compaction and permeability during the out-of-autoclave and vacuum-bag-only manufacturing of a laminate composite with aligned carbon nanofibers

    Science.gov (United States)

    Mann, Erin

    Both industry and commercial entities are in the process of using more lightweight composites. Fillers, such as fibers, nanofibers and other nanoconstituents in polymer matrix composites have been proven to enhance the properties of composites and are still being studied in order to optimize the benefits. Further optimization can be studied during the manufacturing process. The air permeability during the out-of-autoclave-vacuum-bag-only (OOA-VBO) cure method is an important property to understand during the optimization of manufacturing processes. Changes in the manufacturing process can improve or decrease composite quality depending on the ability of the composite to evacuate gases such as air and moisture during curing. Therefore, in this study, the axial permeability of a prepreg stack was experimentally studied. Three types of samples were studied: control (no carbon nanofiber (CNF) modification), unaligned CNF modified and aligned CNF modified samples.

  7. Hybrid core-shell nanowire electrodes utilizing vertically aligned carbon nanofiber arrays for high-performance energy storage

    Science.gov (United States)

    Klankowski, Steven Arnold

    Nanostructured electrode materials for electrochemical energy storage systems have been shown to improve both rate performance and capacity retention, while allowing considerably longer cycling lifetime. The nano-architectures provide enhanced kinetics by means of larger surface area, higher porosity, better material interconnectivity, shorter diffusion lengths, and overall mechanical stability. Meanwhile, active materials that once were excluded from use due to bulk property issues are now being examined in new nanoarchitecture. Silicon was such a material, desired for its large lithium-ion storage capacity of 4,200 mAh g-1 and low redox potential of 0.4 V vs. Li/Li+; however, a ˜300% volume expansion and increased resistivity upon lithiation limited its broader applications. In the first study, the silicon-coated vertically aligned carbon nanofiber (VACNF) array presents a unique core-shell nanowire (NW) architecture that demonstrates both good capacity and high rate performance. In follow-up, the Si-VACNFs NW electrode demonstrates enhanced power rate capabilities as it shows excellent storage capacity at high rates, attributed to the unique nanoneedle structure that high vacuum sputtering produces on the three-dimensional array. Following silicon's success, titanium dioxide has been explored as an alternative high-rate electrode material by utilizing the dual storage mechanisms of Li+ insertion and pseudocapacitance. The TiO 2-coated VACNFs shows improved electrochemical activity that delivers near theoretical capacity at larger currents due to shorter Li+ diffusion lengths and highly effective electron transport. A unique cell is formed with the Si-coated and TiO2-coated electrodes place counter to one another, creating the hybrid of lithium ion battery-pseudocapacitor that demonstrated both high power and high energy densities. The hybrid cell operates like a battery at lower current rates, achieving larger discharge capacity, while retaining one-third of

  8. Processing and Structure of Carbon Nanofiber Paper

    Directory of Open Access Journals (Sweden)

    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.

  9. 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.

  10. Silicon Whisker and Carbon Nanofiber Composite Anode

    Science.gov (United States)

    Ma, Junqing (Inventor); Newman, Aron (Inventor); Lennhoff, John (Inventor)

    2015-01-01

    A carbon nanofiber can have a surface and include at least one crystalline whisker extending from the surface of the carbon nanofiber. A battery anode composition can be formed from a plurality of carbon nanofibers each including a plurality of crystalline whiskers.

  11. Carbon nanofibers obtained from electrospinning process

    Science.gov (United States)

    Bovi de Oliveira, Juliana; Müller Guerrini, Lília; Sizuka Oishi, Silvia; Rogerio de Oliveira Hein, Luis; dos Santos Conejo, Luíza; Cerqueira Rezende, Mirabel; Cocchieri Botelho, Edson

    2018-02-01

    In recent years, reinforcements consisting of carbon nanostructures, such as carbon nanotubes, fullerenes, graphenes, and carbon nanofibers have received significant attention due mainly to their chemical inertness and good mechanical, electrical and thermal properties. Since carbon nanofibers comprise a continuous reinforcing with high specific surface area, associated with the fact that they can be obtained at a low cost and in a large amount, they have shown to be advantageous compared to traditional carbon nanotubes. The main objective of this work is the processing of carbon nanofibers, using polyacrylonitrile (PAN) as a precursor, obtained by the electrospinning process via polymer solution, with subsequent use for airspace applications as reinforcement in polymer composites. In this work, firstly PAN nanofibers were produced by electrospinning with diameters in the range of (375 ± 85) nm, using a dimethylformamide solution. Using a furnace, the PAN nanofiber was converted into carbon nanofiber. Morphologies and structures of PAN and carbon nanofibers were investigated by scanning electron microscopy, Raman Spectroscopy, thermogravimetric analyses and differential scanning calorimeter. The resulting residual weight after carbonization was approximately 38% in weight, with a diameters reduction of 50%, and the same showed a carbon yield of 25%. From the analysis of the crystalline structure of the carbonized material, it was found that the material presented a disordered structure.

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

    International Nuclear Information System (INIS)

    Uyar, Tansel; Çökeliler, Dilek; Doğan, Mustafa; Koçum, Ismail Cengiz; Karatay, Okan; Denkbaş, Emir Baki

    2016-01-01

    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 3 (toughness) in three-point bending test. In addition to the positive results of aligned and non-aligned nanofibers it was found

  13. 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

  14. Magnetic field induced tunability on the thermal conductivity of ferrofluids loaded with carbon nanofibers

    Science.gov (United States)

    Ortiz-Salazar, M.; Pech-May, N. W.; Vales-Pinzon, C.; Medina-Esquivel, R.; Alvarado-Gil, J. J.

    2018-02-01

    In this paper, it is shown that the thermal conductivity of magnetic fluids, formed by a ferrofluid loaded with carbon nanofibers, can be tuned by applying a moderate intensity magnetic field. The tuning is generated by orienting the nanoparticles in the ferrofluid, which in turn partially align the carbon nanofibers, favoring or hindering heat flow along a given direction. Thermal diffusivity at several volume concentrations of nanofibers (0, 0.25, 0.50, 1, 2 and 5%) was measured using the thermal wave resonant cavity technique, located inside a uniform moderate intensity magnetic field. Measurements were performed for random and aligned carbon nanofibers, oriented in the parallel and perpendicular directions with respect to the heat flux. The experimental results show that for 5% volume concentration of carbon nanofibers in the ferrofluid, in random configuration, i.e. without external magnetic field applied, the effective thermal conductivity increased 3 times compared to that of the ferrofluid matrix. Moreover, for parallel alignment of the carbon nanofibers with respect to the heat flux direction, the effective thermal conductivity increased 5 times. However, for perpendicular alignment of the carbon nanofibers with respect to the heat flux direction only a 2 times increment in the effective thermal conductivity is obtained. A 750 G intensity magnetic field is used for both alignment configurations. Additionally, the effect of the concentration of carbon nanofibers on the thermal time-response of the magnetic fluids was studied by switching on/off the magnetic field. The Lewis–Nielsen model was used to interpret the dependence of the thermal conductivity results as a function the concentration and orientation of the carbon nanofibers.

  15. 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.

  16. Formation mechanism of highly aligned nanofibers by a modified bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Shao Zhongbiao

    2018-01-01

    Full Text Available A modified bubble electrospinning by placing a positively charged ring between the bubble and the parallel electrode collector was presented to fabricate highly aligned nanofibers. The theoretical and experimental analyses were carried out to study formation mechanism of highly aligned nanofibers using the modified bubble electrospinning. The results showed the modified bubble electrospinning could decrease the nanofiber diameter, enhance the diameter distribution, and improve the nanofiber alignment.

  17. Functionalization and electrocatalysis on carbon nanofibers

    Science.gov (United States)

    Hogendoorn, Stephanie Ruth

    Nanoscale hybrid materials such as metal nanoparticles dispersed on nanostructured carbons are promising for use as electrocatalysts due to their chemical and physical properties. Vertically aligned carbon nanofibers (VACNFs) have a unique structure that exposes large amounts of graphitic edge-plane along the sidewalls, suggesting that hybrid VACNF-nanoparticle structures may have particularly good electrochemical response for electrocatalytic reactions. As with other carbon materials, the surface of VACNFs is not highly selective, but the high reactivity of the graphitic edge-plane sites allows for chemical modification with functional organic monolayers, avoiding the need for harsh oxidation techniques. The use of molecular functionalization to interface VACNFs with catalytic metal particles was investigated using two different growth techniques: electroless deposition and pulsed electrochemical deposition. Deposited particles are demonstrated to be catalytically active, despite the presence of the molecular layer. The presence of graphitic edge-plane is found to be important for electrochemical nucleation. Evaluation of the catalytic behavior of this hybrid system using the methanol oxidation reaction as a model system reveals differences in initial catalytic activity and long-term stability of nanoparticles produced by the two growth methods. Development of the electrochemical deposition method demonstrates that nucleation and growth can be controlled by the use of multiple-pulse sequences. This work provides insights into the use of molecular systems for chemical selectivity and the importance of edge-plane sites in catalytic activity of carbon-based hybrid nanostructures.

  18. Electrospun Carbon Nanotube-Reinforced Nanofiber.

    Science.gov (United States)

    Kim, Sung Mm; Hee Kim, Sung; Choi, Myong Soo; Lee, Jun Young

    2016-03-01

    We fabricated multi-walled carbon nanotube (MWNT) reinforced polyurethane (PU) nanofiber (MWNT-PU) web via electrospinning. In order to optimize the electrospinning conditions, we investigated the effects of various parameters including kind of solvent, viscosity of the spinning solution, and flow rate on the spinnability and properties of nanofiber. N,N-dimethylformamide (DMF), tetrahydrofuran (THF) and their mixture with various volume ratio were used as the spinning solvent. Morphology of the nanofiber was studied using scanning electron microscope (SEM) and transmission electron microscope (TEM), confirming successful fabrication of MWNT-PU nanofiber web with uniform dispersion of MWNT in longitudinal direction of the fiber. The MWNT-PU nanofiber web exhibited two times higher tensile strength than PU nanofiber web. We also fabricated electrically conducting MWNT-PU nanofiber web by coating poly(3,4-ehtylenedioxythiophene) (PEDOT) on the surface of MWNT-PU nanofiber web for electromagnetic interference (EMI) shielding application. The electromagnetic interference shielding effectiveness (EMI SE) was quite high as 25 dB in the frequency range from 50 MHz to 10 GHz.

  19. Simulation of the Impact of Si Shell Thickness on the Performance of Si-Coated Vertically Aligned Carbon Nanofiber as Li-Ion Battery Anode

    Science.gov (United States)

    Das, Susobhan; Li, Jun; Hui, Rongqing

    2015-01-01

    Micro- and nano-structured electrodes have the potential to improve the performance of Li-ion batteries by increasing the surface area of the electrode and reducing the diffusion distance required by the charged carriers. We report the numerical simulation of Lithium-ion batteries with the anode made of core-shell heterostructures of silicon-coated carbon nanofibers. We show that the energy capacity can be significantly improved by reducing the thickness of the silicon anode to the dimension comparable or less than the Li-ion diffusion length inside silicon. The results of simulation indicate that the contraction of the silicon electrode thickness during the battery discharge process commonly found in experiments also plays a major role in the increase of the energy capacity. PMID:28347120

  20. Simulation of the Impact of Si Shell Thickness on the Performance of Si-Coated Vertically Aligned Carbon Nanofiber as Li-Ion Battery Anode

    Directory of Open Access Journals (Sweden)

    Susobhan Das

    2015-12-01

    Full Text Available Micro- and nano-structured electrodes have the potential to improve the performance of Li-ion batteries by increasing the surface area of the electrode and reducing the diffusion distance required by the charged carriers. We report the numerical simulation of Lithium-ion batteries with the anode made of core-shell heterostructures of silicon-coated carbon nanofibers. We show that the energy capacity can be significantly improved by reducing the thickness of the silicon anode to the dimension comparable or less than the Li-ion diffusion length inside silicon. The results of simulation indicate that the contraction of the silicon electrode thickness during the battery discharge process commonly found in experiments also plays a major role in the increase of the energy capacity.

  1. Simulation of the Impact of Si Shell Thickness on the Performance of Si-Coated Vertically Aligned Carbon Nanofiber as Li-Ion Battery Anode.

    Science.gov (United States)

    Das, Susobhan; Li, Jun; Hui, Rongqing

    2015-12-15

    Micro- and nano-structured electrodes have the potential to improve the performance of Li-ion batteries by increasing the surface area of the electrode and reducing the diffusion distance required by the charged carriers. We report the numerical simulation of Lithium-ion batteries with the anode made of core-shell heterostructures of silicon-coated carbon nanofibers. We show that the energy capacity can be significantly improved by reducing the thickness of the silicon anode to the dimension comparable or less than the Li-ion diffusion length inside silicon. The results of simulation indicate that the contraction of the silicon electrode thickness during the battery discharge process commonly found in experiments also plays a major role in the increase of the energy capacity.

  2. Carbon Nanofiber Electrode Array for Neurochemical Monitoring

    Science.gov (United States)

    Koehne, Jessica E.

    2017-01-01

    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 using vertically aligned CNF as neurotransmitter recording electrodes for application in a smart deep brain stimulation (DBS) device. 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.

  3. Fabrication of Carbon Nanotube Polymer Actuator Using Nanofiber Sheet

    Science.gov (United States)

    Kato, Hayato; Shimizu, Akikazu; Sato, Taiga; Kushida, Masahito

    2017-11-01

    Carbon nanotube polymer actuators were developed using composite nanofiber sheets fabricated by multi-walled carbon nanotubes(MWCNTs) and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Nanofiber sheets were fabricated by electrospinning method. The effect of flow rate and polymer concentration on nanofiber formation were verified for optimum condition for fabricating nanofiber sheets. We examined the properties of MWCNT/PVDF-HFP nanofiber sheets, as follows. Electrical conductivity and mechanical strength increased as the MWCNT weight ratio increased. We fabricated carbon nanotube polymer actuators using MWCNT/PVDF-HFP nanofiber sheets and succeeded in operating of our actuators.

  4. Carbon nanofibers: catalytic synthesis and applications

    NARCIS (Netherlands)

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

    2000-01-01

    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

  5. Carbon nanofiber growth on thin rhodium layers

    NARCIS (Netherlands)

    Chinthaginjala, J.K.; Unnikrishnan, S.; Smithers, Mark A.; Smithers, M.A.; Kip, Gerhardus A.M.; Lefferts, Leonardus

    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

  6. Helix Electrohydrodynamic Printing of Highly Aligned Serpentine Micro/Nanofibers

    Directory of Open Access Journals (Sweden)

    Yongqing Duan

    2017-09-01

    Full Text Available Micro/nano serpentine structures have widespread applications in flexible/stretchable electronics; however, challenges still exist for low-cost, high-efficiency and controllable manufacturing. Helix electrohydrodynamic printing (HE-printing has been proposed here to realize controllable direct-writing of large area, highly aligned serpentine micro/nanofibers by introducing the rope coiling effect into printing process. By manipulating the flying trajectory and solidification degree of the micro/nano jet, the solidified micro/nanofiber flying in a stabilized helical manner and versatile serpentine structures deposited on a moving collector have been achieved. Systematic experiments and theoretical analysis were conducted to study the transformation behavior and the size changing rules for various deposited microstructures, and highly aligned serpentine microfibers were directly written by controlling the applied voltage, nozzle-to-collector distance and collector velocity. Furthermore, a hyper-stretchable piezoelectric device that can detect stretching, bending and pressure has been successfully fabricated using the printed serpentine micro/nanofibers, demonstrating the potential of HE-printing in stretchable electronics manufacturing.

  7. Carbon nanofibers in catalytic membrane microreactors

    NARCIS (Netherlands)

    Aran, H.C.; Pacheco Benito, Sergio; Luiten-Olieman, Maria W.J.; Er, S.; Wessling, Matthias; Lefferts, Leonardus; Benes, Nieck Edwin; Lammertink, Rob G.H.

    2011-01-01

    In this study, we report on the fabrication and operation of new hybrid membrane microreactors for gas–liquid–solid (G–L–S) reactions. The presented reactors consist of porous stainless steel tubes onto which carbon nanofibers (CNFs) are grown as catalyst support, all encapsulated by a gas permeable

  8. 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.

  9. Dielectric transition of polyacrylonitrile derived carbon nanofibers

    International Nuclear Information System (INIS)

    Li, Jiangling; Su, Shi; Abbot, Andrew M; Ye, Haitao; Zhou, Lei

    2014-01-01

    The dielectric behavior of polyacrylonitrile derived carbon nanofibers formed at different carbonization temperatures was investigated using impedance spectroscopy. The impedance data are presented in the form of Cole–Cole plots and four equivalent electrical circuits are derived. It is found that by increasing carbonization temperature from 500 to 800 °C, a strong capacitive element in the parallel equivalent circuit is transformed into an inductive element, while the contact resistance and parallel resistance are significantly decreased. Along with the morphological and chemical structural evolution, respectively witnessed by scanning electron microscopy and Raman spectroscopy, the dielectric transition deduced from the transformation of electrical circuits can be correlated to the proposed microstructural changes of polyacrylonitrile derived carbon nanofibers and the interaction/interference among them. (paper)

  10. Improved electrical conductivity of poly(ethylene oxide) nanofibers using multi-walled carbon nanotubes

    Science.gov (United States)

    Lee, J. Y.; Kang, T.-H.; Choi, J. H.; Choi, I.-S.; Yu, W.-R.

    2018-03-01

    Highly conductive nanofibers with 1570 S/m were obtained from an electrospun solution of polymer containing multiwalled carbon nanotubes (MWCNTs). Homogeneous dispersion of high concentrations of MWCNTs was achieved by attaching poly(styrenesulfonic acid graft aniline) (PSS-g-ANI), an amphiphilic surfactant, to the MWCNT surface. The hydrophilic sulfonic acid group facilitated the dissolution of PSS-g-ANI-grafted MWCNTs in a polyethylene oxide (PEO) solution up to 6.7 wt% MWCNT. To our knowledge, this is the highest level of MWCNT doping attained in a solution designed for electrospinning. With the incorporation of PSS-g-ANI, the concentration of MWCNTs embedded in the electrospun nanofibers increased. More importantly, the alignment of MWCNTs along the nanofiber axis increased significantly, as confirmed by observed birefringence under crossed polarizers. The combination of higher doping levels and better alignment afforded highly conductive nanofibers suitable for electronic nanodevices.

  11. Improved electrical conductivity of poly(ethylene oxide nanofibers using multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    J. Y. Lee

    2018-03-01

    Full Text Available Highly conductive nanofibers with 1570 S/m were obtained from an electrospun solution of polymer containing multiwalled carbon nanotubes (MWCNTs. Homogeneous dispersion of high concentrations of MWCNTs was achieved by attaching poly(styrenesulfonic acid graft aniline (PSS-g-ANI, an amphiphilic surfactant, to the MWCNT surface. The hydrophilic sulfonic acid group facilitated the dissolution of PSS-g-ANI-grafted MWCNTs in a polyethylene oxide (PEO solution up to 6.7 wt% MWCNT. To our knowledge, this is the highest level of MWCNT doping attained in a solution designed for electrospinning. With the incorporation of PSS-g-ANI, the concentration of MWCNTs embedded in the electrospun nanofibers increased. More importantly, the alignment of MWCNTs along the nanofiber axis increased significantly, as confirmed by observed birefringence under crossed polarizers. The combination of higher doping levels and better alignment afforded highly conductive nanofibers suitable for electronic nanodevices.

  12. Carbon nanofibers: a versatile catalytic support

    Directory of Open Access Journals (Sweden)

    Nelize Maria de Almeida Coelho

    2008-09-01

    Full Text Available The aim of this article is present an overview of the promising results obtained while using carbon nanofibers based composites as catalyst support for different practical applications: hydrazine decomposition, styrene synthesis, direct oxidation of H2S into elementary sulfur and as fuel-cell electrodes. We have also discussed some prospects of the use of these new materials in total combustion of methane and in ammonia decomposition. The macroscopic carbon nanofibers based composites were prepared by the CVD method (Carbon Vapor Deposition employing a gaseous mixture of hydrogen and ethane. The results showed a high catalytic activity and selectivity in comparison to the traditional catalysts employed in these reactions. The fact was attributed, mainly, to the morphology and the high external surface of the catalyst support.

  13. Electrocatalytic properties of Pt/carbon composite nanofibers

    International Nuclear Information System (INIS)

    Lin Zhan; Ji Liwen; Zhang Xiangwu

    2009-01-01

    Pt/carbon composite nanofibers were prepared by electrodepositing Pt nanoparticles directly onto electrospun carbon nanofibers. The morphology and size of Pt nanoparticles were controlled by the electrodeposition time. The resulting Pt/carbon composite nanofibers were characterized by running cyclic voltammograms in 0.20 M H 2 SO 4 and 5.0 mM K 4 [Fe(CN) 6 ] + 0.10 M KCl solutions. The electrocatalytic activities of Pt/carbon composite nanofibers were measured by the oxidation of methanol. Results show that Pt/carbon composite nanofibers possess the properties of high active surface area and fast electron transfer rate, which lead to a good performance towards the electrocatalytic oxidation of methanol. It is also found that the Pt/carbon nanofiber electrode with a Pt loading of 0.170 mg cm -2 has the highest activity.

  14. Fabrication of Aligned Nanofibers by Manipulated Rotating Drum Method and Studying the Effective Parameters on Fibers Alignment by Image Processing

    Directory of Open Access Journals (Sweden)

    Zohreh Hadi

    2013-01-01

    Full Text Available Electrospinning is a known process to produce nanofibers through electrostatic forces. In a typical process, an electrical potential is applied between droplets of polymer solution or melt, held through a syringe needle and a grounded target. In general electrospinning fibers are collected on the grounded target as a random oriented web of nanofiber. Various research projects are attempted to obtain aligned electrospun fibers. This modified electrospinning method can be developed and used in a variety of nanofiber-based applications such as making of nanofibrous scaffolds for tissue engineering. In this study, an effective method has been developed to fabricate aligned nanofibers by manipulation of electrospinning system using two nozzles with opposite charges. Moreover, the effect of some parameters including take-up velocity, applied voltage and polymer solution concentration on alignment of produced nanofibers is investigated. The comparison of fibers alignment was carried out by programming and image processing in MATLAB. It is shown that take-up velocity and polymer solution concentration have significant effect on increasing the fibers alignment. Also, the alignment is increased with applied voltage at first and then, it is decreased. The analytical results and optical microscopic images are clear evidence of showing the maximum alignment of nanofibers obtained at 15% polymer solution concentration with take-up velocity of 600 rpm and 11 kV voltage.

  15. A bioengineered peripheral nerve construct using aligned peptide amphiphile nanofibers

    Science.gov (United States)

    Yalom, Anisa; Berns, Eric J.; Stephanopoulos, Nicholas; McClendon, Mark T.; Segovia, Luis A.; Spigelman, Igor; Stupp, Samuel I.; Jarrahy, Reza

    2014-01-01

    Peripheral nerve injuries can result in lifelong disability. Primary coaptation is the treatment of choice when the gap between transected nerve ends is short. Long nerve gaps seen in more complex injuries often require autologous nerve grafts or nerve conduits implemented into the repair. Nerve grafts, however, cause morbidity and functional loss at donor sites, which are limited in number. Nerve conduits, in turn, lack an internal scaffold to support and guide axonal regeneration, resulting in decreased efficacy over longer nerve gap lengths. By comparison, peptide amphiphiles (PAs) are molecules that can self-assemble into nanofibers, which can be aligned to mimic the native architecture of peripheral nerve. As such, they represent a potential substrate for use in a bioengineered nerve graft substitute. To examine this, we cultured Schwann cells with bioactive PAs (RGDS-PA, IKVAV-PA) to determine their ability to attach to and proliferate within the biomaterial. Next, we devised a PA construct for use in a peripheral nerve critical sized defect model. Rat sciatic nerve defects were created and reconstructed with autologous nerve, PLGA conduits filled with various forms of aligned PAs, or left unrepaired. Motor and sensory recovery were determined and compared among groups. Our results demonstrate that Schwann cells are able to adhere to and proliferate in aligned PA gels, with greater efficacy in bioactive PAs compared to the backbone-PA alone. In vivo testing revealed recovery of motor and sensory function in animals treated with conduit/PA constructs comparable to animals treated with autologous nerve grafts. Functional recovery in conduit/PA and autologous graft groups was significantly faster than in animals treated with empty PLGA conduits. Histological examinations also demonstrated increased axonal and Schwann cell regeneration within the reconstructed nerve gap in animals treated with conduit/PA constructs. These results indicate that PA nanofibers may

  16. The effect of electrospun nanofibers alignment on the synthesis of one-dimensional silicon carbide nanostructure

    Science.gov (United States)

    Hooshyar, Ali; Kokabi, Mehrdad

    2018-01-01

    One-dimensional silicon carbide (1D SiC) nanostructure has shown unusual properties such as extremely high strength, good flexibility, fracture toughness, wide band gap ( 3.2eV), large breakdown electric field strength (>2 MV cm-1, 10 times that of silicon), and inverse Hall-Petch effect. Because of these advantages, 1D SiC nanomaterial has gained extensive attention on the wide range of applications in microelectronics, optoelectronics, nanocomposites, and catalyst supports. Many methods have been used for the synthesis of 1D SiC nanostructures such as chemical vapor deposition, carbon nanotube-confined reaction, laser ablation, high-frequency induction heating, and arc discharge. However, these methods have also some shortcomings such as using catalyst, high-cost, low yield, irregular geometry and impurity. In this work, electrospinning was used to prepare aligned PVA/SiO2 composite nanofibers and the effect of fiber alignment on the production efficiency and quality of 1D SiC nanostructure was investigated. For this purpose, aligned electrospun nanofibers, as the desirable precursor, were put in a tube furnace and heated up to 1250°C under a controlled program in an inert atmosphere. Finally, the grown 1D SiC nanostructure product was characterized using SEM, XRD, and FTIR. The results confirmed the successful synthesis of pure crystalline1D β-SiC nanostructure with high yield, more regular, and metal catalyst-free.

  17. Carbon composites composites with carbon fibers, nanofibers, and nanotubes

    CERN Document Server

    Chung, Deborah D L

    2017-01-01

    Carbon Composites: Composites with Carbon Fibers, Nanofibers, and Nanotubes, Second Edition, provides the reader with information on a wide range of carbon fiber composites, including polymer-matrix, metal-matrix, carbon-matrix, ceramic-matrix and cement-matrix composites. In contrast to other books on composites, this work emphasizes materials rather than mechanics. This emphasis reflects the key role of materials science and engineering in the development of composite materials. The applications focus of the book covers both the developing range of structural applications for carbon fiber composites, including military and civil aircraft, automobiles and construction, and non-structural applications, including electromagnetic shielding, sensing/monitoring, vibration damping, energy storage, energy generation, and deicing. In addition to these new application areas, new material in this updated edition includes coverage of cement-matrix composites, carbon nanofibers, carbon matrix precursors, fiber surface ...

  18. The synthesis of titanium carbide-reinforced carbon nanofibers

    Science.gov (United States)

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

    2009-06-01

    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.

  19. Template synthesis and magnetic properties of highly aligned barium hexaferrite (BaFe12O19) nanofibers

    International Nuclear Information System (INIS)

    Huang, Boneng; Li, Congju; Wang, Jiaona

    2013-01-01

    Using electrospun poly(ethylene terephthalate)/citric acid (PET/CA) microfibers as the template, highly aligned barium hexaferrite (BaFe 12 O 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 12 O 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 12 O 19 nanofibers were of random orientations. The formation mechanism of aligned BaFe 12 O 19 nanofibers was proposed based on experiment. The magnetic measurement revealed that the aligned BaFe 12 O 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 12 O 19 nanofibers. ► The aligned BaFe 12 O 19 nanofibers display an obvious orientation-dependent magnetic behavior. ► The method can be readily applied to other aligned one-dimensional inorganic nanomaterials

  20. Highly anisotropic electric conductivity in PAN-based carbon nanofibers

    Science.gov (United States)

    Aprojanz, J.; Dreyer, B.; Wehr, M.; Wiegand, J.; Baringhaus, J.; Koch, J.; Renz, F.; Sindelar, R.; Tegenkamp, C.

    2017-12-01

    In addition to the chemical and physical properties of nanostructures their successful utilization for applications is strongly triggered by economic aspects. Electrospinning of nanowires from solution followed by subsequent annealing steps is a comparably cheap technique to fabricate conductive carbon nanofibers (CNF) made from polyacrylonitrile (PAN) molecules in large quantities. In this work, we investigated the microscopic properties of the CNFs with diameters of 100-300 nm by means of Raman and x-ray photoelectron spectroscopy and correlated these results with transport measurements done with a 4-tip STM. In particular, we investigated the effect of fiber alignment and knot densities, which can be controlled by applying constant creep due to stress during the stabilization process. The comparison of the conductivity obtained from single CNFs revealed further that the fiber crossings within the ensemble structure act as scattering centers and proofs that the transport is along the surfaces of the CNFs.

  1. 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.

  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. Silicon Whisker and Carbon Nanofiber Composite Anode, Phase I

    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...

  4. Silicon Whisker and Carbon Nanofiber Composite Anode, Phase II

    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...

  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. 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.

  7. Plasma based platinum nanoaggregates deposited on carbon nanofibers improve fuel cell efficiency

    Science.gov (United States)

    Caillard, Amaël; Charles, Christine; Boswell, Rod; Brault, Pascal; Coutanceau, Christophe

    2007-05-01

    Improved platinum catalytic utilization has been achieved by creating an open support structure based on aligned carbon nanofibers (CNFs) attached to carbon loaded carbon cloth electrodes [known as gas diffusion layer (GDL)]. The nickel catalyst used to initiate the CNFs growth; the CNFs themselves and the 5nm Pt nanoaggregates were deposited sequentially in the same low pressure plasma reactor. This oriented catalyst structure was incorporated into a membrane electrode assembly and tested with and without CNFs and on carbon paper or GDL. The performance of the fuel cells based on CNFs and GDL was better over the entire range of operating current.

  8. Functionalized carbon nanotubes and nanofibers for biosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun; Lin, Yuehe

    2008-07-30

    This review summarizes the recent advances of carbon nanotube (CNT) and carbon nanofiber (CNF)-based electrochemical biosensors with an emphasis on the applications of CNTs. Carbon nanotubes and carbon nanofibers have unique electric, electrocatalytic, and mechanical properties which make them efficient materials for the use in electrochemical biosensor development. In this article, the functionalization of CNTs for biosensors is simply discussed. The electrochemical biosensors based on CNT and their various applications, e.g., measurement of small biological molecules and environmental pollutants, detection of DNA, and immunosensing of disease biomarkers, are reviewed. Moreover, the development of carbon nanofiber-based electrochemical biosensors and their applications are outlined. Finally, some challenges are discussed in the conclusion.

  9. A continuous process to align electrospun nanofibers into parallel and crossed arrays

    Energy Technology Data Exchange (ETDEWEB)

    Laudenslager, Michael J.; Sigmund, Wolfgang M., E-mail: wsigm@mse.ufl.edu [University of Florida, Department of Materials Science and Engineering (United States)

    2013-04-15

    Electrical, optical, and mechanical properties of nanofibers are strongly affected by their orientation. Electrospinning is a nanofiber processing technique that typically produces nonwoven meshes of randomly oriented fibers. While several alignment techniques exist, they are only able to produce either a very thin layer of aligned fibers or larger quantities of fibers with less control over their alignment and orientation. The technique presented herein fills the gap between these two methods allowing one to produce thick meshes of highly oriented nanofibers. In addition, this technique is not limited to collection of fibers along a single axis. Modifications to the basic setup allow collection of crossed fibers without stopping and repositioning the apparatus. The technique works for a range of fiber sizes. In this study, fiber diameters ranged from 100 nm to 1 micron. This allows a few fibers at a time to rapidly deposit in alternating directions creating an almost woven structure. These aligned nanofibers have the potential to improve the performance of energy storage and thermoelectric devices and hold great promise for directed cell growth applications.

  10. Alignment of Electrospun Nanofibers and Prediction of Electrospinning Linear Speed Using a Rotating Jet

    Directory of Open Access Journals (Sweden)

    M. Khamforoush

    2009-12-01

    Full Text Available Anew and effective electrospinning method has been developed for producing aligned polymer nanofibers. The conventional electrospinning technique has been modified to fabricate nanofibers as uniaxially aligned array. The key to the success of this technique is the creation of a rotating jet by using a cylindrical collector in which the needle tip is located at its center. The unique advantage of this method among the current methods is the ability of apparatus to weave continuously nanofibers in uniaxially aligned form. Fibers produced by this method are well-aligned, with several meters in length, and can be spread over a large area. We have employed a voltage range of (6-16 kV, a collector diameter in the range of 20-50 cm and various concentrations of PAN solutions ranging from 15 wt% to 19 wt %. The electrospun nanofibers could be conveniently formed onto the surface of any thin substrate such as glass sampling plate for subsequent treatments and other applications. Therefore, the linear speed of electrospinning process is determined experimentally as a function of cylindrical collector diameter, polymer concentration and field potential  difference.

  11. 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.

  12. Treated Carbon Nanofibers for Storing Energy in Aqueous KOH

    Science.gov (United States)

    Firsich, David W.

    2004-01-01

    A surface treatment has been found to enhance the performances of carbon nanofibers as electrode materials for electrochemical capacitors in which aqueous solutions of potassium hydroxide are used as the electrolytes. In the treatment, sulfonic acid groups are attached to edge plane sites on carbon atoms. The treatment is applicable to a variety of carbon nanofibers, including fibrils and both single- and multiple-wall nanotubes. The reason for choosing nanofibers over powders and other forms of carbon is that nanofibers offer greater power features. In previous research, it was found that the surface treatment of carbon nanofibers increased energy-storage densities in the presence of acid electrolytes. Now, it has been found that the same treatment increases energy-storage densities of carbon nanofibers in the presence of alkaline electrolytes when the carbon is paired with a NiOOH electrode. This beneficial effect varies depending on the variety of carbon substrate to which it is applied. It has been conjectured that the sulfonic acid groups, which exist in a deprotonated state in aqueous KOH solutions, undergo reversible electro-chemical reactions that are responsible for the observed increases in energystorage capacities. The increases can be considerable: For example, in one case, nanofibers exhibited a specific capacitance of 34 Farads per gram before treatment and 172 Farads per gram (an increase of about 400 percent) after treatment. The most promising application of this development appears to lie in hybrid capacitors, which are devices designed primarily for storing energy. These devices are designed to be capable of (1) discharge at rates greater than those of batteries and (2) storing energy at densities approaching those of batteries. A hybrid capacitor includes one electrode like that of a battery and one electrode like that of an electrochemical capacitor. For example, a hybrid capacitor could contain a potassium hydroxide solution as the electrolyte

  13. Process Optimization and Emperical Modelling for Electrospun Polyacrylonitrile (PAN) Nanofiber Precursor of Carbon nanofibers

    NARCIS (Netherlands)

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

  14. Synthesis of Carbon Nanofibers on Large Woven Cloth

    NARCIS (Netherlands)

    Kotanjac, Zeljko; Lefferts, Leonardus; Koysin, V.; Warnet, Laurent; Akkerman, Remko

    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

  15. 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

  16. 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

    2016-12-05

    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.

  17. Dry adhesives from carbon nanofibers grown in an open ethanol flame

    Directory of Open Access Journals (Sweden)

    Christian Lutz

    2017-12-01

    Full Text Available Based on magnetic-field-assisted growth of carbon nanofibers in an open ethanol flame we fabricated arrays of carbon nanofibers with different degrees of orientation. Inspired by the dry adhesive system of geckos we investigated the adhesive properties of such carbon nanofiber arrays with ordered and random orientation. AFM-based force spectroscopy revealed that adhesion force and energy rise linear with preload force. Carbon nanofibers oriented by a magnetic field show a 68% higher adhesion (0.66 N/cm2 than the randomly oriented fibers. Endurance tests revealed that the carbon nanofiber arrays withstand 50.000 attachment/detachment cycles without observable wear.

  18. Synthesis and characterization of carbon nanofibers grown on Ni and Mo catalysts by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Eun Yi; Park, Heai Ku; Lee, Chang Seop [Keimyung University, Deagu (Korea, Republic of); Choi, Jong Ha [Dept. of Applied Chemistry, Andong National University, Andong (Korea, Republic of)

    2015-05-15

    In this study, we synthesized carbon nanofibers using Ni and Mo catalysts by chemical vapor deposition. Catalysts used in the synthesis of carbon nanofibers were prepared by changing the molar ratio of nickel nitrate and ammonium molybdate. Precipitates were then obtained by reacting with ammonium carbonate. The optimum temperature for synthesis of carbon nanofibers was found by changing it between 600 and 800 °C. At these temperatures, carbon nanofibers were synthesized with various ratios of catalysts. Structural and physiochemical properties were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy. The specific surface area of synthesized carbon nanofibers was measured by BET. It was found that characterization of carbon nanofibers were significantly affected by the synthesis temperature and the concentration ratio of metal catalysts. When the catalyst with the concentration ratio of Ni and Mo was 6:4 at 800 °C, uniform carbon nanofibers with a diameter of 50 nm were grown. Crystallinity and amorphicity of the synthesized carbon nanofiber were excellent compared to those of carbon nanofibers synthesized with metal catalysts in different concentration ratios. A three-electrode cell was prepared by using the synthesized carbon nanofibers as anode of Li secondary battery. The electrochemical properties of carbon nanofibers were examined through cyclic voltammetry and galvanostatic charge–discharge.

  19. High-Performance Cementitious Matrix using Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    Muhammad Maqbool Sadiq Awan

    2017-03-01

    Full Text Available Graphite nanomaterials would realize their reinforcement potential within cement-based materials when they are thoroughly dispersed and effectively bonded to cement hydrates. Thorough dispersion of graphite nanomaterials in the fresh cementitious matrix encounters challenges associated with the hydrophobic nature of nanomaterial surfaces and their strong tendency towards agglomeration via attractive van der Waals forces. Effective interfacial interactions with cement hydrates are further challenged by the relatively inert nature of nanomaterial surfaces. An experimental program was conducted with the objective of effectively utilizing both acid-oxidized and pristine carbon nanofibers towards reinforcement of high-performance cementitious pastes. Hybrid reinforcement systems comprising optimum volume fraction of carbon nanofibers and micro-scale fibers were also evaluated in cementitious matrices. The improvements in nanofiber dispersion and interfacial interactions resulting from acid-oxidation and use of proper dispersion techniques were found to bring about significant gains in the engineering properties of high-performance cementitious materials.

  20. Nanoscratch technique for aligning multiwalled carbon nanotubes ...

    Indian Academy of Sciences (India)

    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. Keywords. Carbon nanotube; arc discharge; characterization; alignment; nanoscratch. 1.

  1. 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.

  2. Low-frequency electrohydrodynamic convection patterns in nematic liquid crystal aligned using parallel-oriented nanofiber

    Science.gov (United States)

    Mahendra, Bhisma; Nugroho, Fahrudin; Yusuf, Yusril

    2018-02-01

    Parallel-aligned poly(vinyl alcohol) (PVA) nanofiber with a diameter of 240 ± 60 nm and an alignment parameter (S) of 0.95 ± 0.16 was obtained by a gap collector electrospinning that used copper (Cu) as a collector. The sandwiched cells (the horizontal-view and longitudinal-view) nematic liquid crystal was prepared by treating glass surfaces with the aligned PVA nanofiber to provide uniform anchoring of the director. When an electric field was applied to these samples, the electrohydrodynamic convection (EHC) pattern was observed. In the longitudinal-view cells, above a threshold voltage at low frequency, a typically low-frequency EHC rolls i.e., a Williams domain (WD) pattern was observed. By increasing the voltage, a fluctuating Williams domain (FWD) and grid patterns (GPs) could also be observed. In the transverse-view cells, at low-frequency regimes, WD, sawtooth patterned (STP), and dynamic scattering mode (DSM) patterns were observed. By replacing the conventional rubbing method with the use of parallel-aligned nanofibers, the well-known EHC phenomenon also could be observed.

  3. Charge injection from carbon nanofibers into hexane under ambient conditions

    NARCIS (Netherlands)

    Agiral, A.; Eral, Burak; van den Ende, Henricus T.M.; Gardeniers, Johannes G.E.

    2011-01-01

    The observation of charge injection from carbon nanofibers (CNFs) into liquid hexane under ambient conditions is reported. A CNF-coated electrode and a counter electrode are brought into micrometer proximity in a quasi-parallel geometry using a strain-gauge-based proximity sensor. Controlled charge

  4. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. 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.

  6. Reverse Kebab Structure Formed inside Carbon Nanofibers via Nanochannel Flow.

    Science.gov (United States)

    Nie, Min; Kalyon, Dilhan M; Fisher, Frank T

    2015-09-15

    The morphology of polymers inside a confined space has raised great interest in recent years. However, polymer crystallization within a one-dimensional carbon nanostructure is challenging due to the difficulty of polar solvents carrying polymers to enter a nonpolar graphitic nanotube in bulk solution at normal temperature and pressure. Here we describe a method whereby nylon-11 was crystallized and periodically distributed on the individual graphitic nanocone structure within hollow carbon nanofibers (CNF). Differential scanning calorimetry and X-ray diffraction indicate that the nylon polymer is in the crystalline phase. A mechanism is suggested for the initiation of nanochannel flow in a bulk solvent as a prerequisite condition to achieve interior polymer crystallization. Selective etching of polymer crystals on the outer wall of CNF indicates that both surface tension and viscosity affect the flow within the CNF. This approach provides an opportunity for the interior functionalization of carbon nanotubes and nanofibers for applications in the biomedical, energy, and related fields.

  7. 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.

  8. Thermal and Electrical Characterization of the Carbon Nanofibers Based Cement Composites

    Directory of Open Access Journals (Sweden)

    Agnieszka ŚLOSARCZYK

    2017-08-01

    Full Text Available The paper describes the influence of chemical modification of vapor grown carbon nanofibers (VGCnFs on the thermal and electrical properties of the cement composites. The surface modification of nanofibers was performed by means of ozone and nitric acid treatments. It was shown that the oxidized carbon nanofibers surface plays an important role in shaping the mechanical and especially electrical properties of cement composite. For cement matrix modified with carbon nanofibers subjected to oxidized treatment, the slightly increase of cement paste resistivity was observed. It confirms the better adhesion of carbon nanofibers to cement paste. However, independently of carbon nanofibers modification, the occurrence of VGCnFs in cement paste increased the electrical conductivity of the composite in comparison to the cement paste without fibers. The obtained values of electrical resistivity were comparable with values of cement composites modified with 4 mm long carbon fibers. Moreover, it was shown that the chemical modification of carbon nanofibers surface does not influence on the thermal properties of cement composites. In case of cement paste with unmodified and modified carbon nanofibers, the Seebeck voltage was proportional to the temperature difference and was independent of the oxidation degree of carbon nanofibers.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.14993

  9. Fabrication and Characterization of High Temperature Resin/Carbon Nanofiber Composites

    Science.gov (United States)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    Multifunctional composites present a route to structural weight reduction. Nanoparticles such as carbon nanofibers (CNF) provide a compromise as a lower cost nanosize reinforcement that yields a desirable combination of properties. Blends of PETI-330 and CNFs were prepared and characterized to investigate the potential of CNF composites as a high performance structural medium. Dry mixing techniques were employed and the effect of CNF loading level on melt viscosity was determined. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, samples containing 30 and 40 wt% CNF were scaled up to approx.300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280 C into a stainless steel tool followed by curing for 1 h at 371 C. The tool was designed to impart high shear during the process in an attempt to achieve some alignment of CNFs in the flow direction. Moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of CNFs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/CNF composites are discussed. Keywords: resins, carbon nanofibers, scanning electron microscopy, electrical properties, thermal conductivity,injection

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

    Science.gov (United States)

    Jung, Kyung-Hye; Ferraris, John P

    2016-10-21

    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.

  11. 3D printed multiplexed electrospinning sources for large-scale production of aligned nanofiber mats with small diameter spread

    Science.gov (United States)

    García-López, Erika; Olvera-Trejo, Daniel; Velásquez-García, Luis F.

    2017-10-01

    We report the design, fabrication, and characterization of novel, low-cost, and modular miniaturized nanofiber electrospinning sources for the scalable production of non-woven aligned nanofiber mats with low diameter variation. The devices are monolithic arrays of electrospinning emitters made via stereolithography; the emitters are arranged so each element has an independent line of sight to a rotating collector surface. Linear and zigzag emitter packing were evaluated using a PEO solution with the aim of maximizing the throughput of nanofibers with the smallest diameter and narrowest distribution. Current versus flowrate characterization of the devices showed that for a given flowrate a zigzag array produces more current per emitter than a linear array of the same emitter pitch and array size. In addition, the data demonstrate that larger and denser arrays have a net gain in flow rate per unit of active length. Visual inspection of the devices suggests uniform operation in devices with as many as 17 emitters with 300 μm inner diameter and 1.5 mm emitter gap. Well-aligned nanofiber mats were collected on a rotating drum and characterized; the 17-emitter device produced the same narrow nanofiber distribution (˜81 nm average diameter, ˜17 nm standard deviation) for all tested flow rates, which is strikingly different to the performance shown by 1-emitter sources where the average fiber diameter significantly increased and the statistics notably widened when the flowrate increases. Therefore, the data demonstrate that massively multiplexing the emitters is a viable approach to greatly increase the throughput of non-woven aligned nanofiber mats without sacrificing the statistics of the nanofibers generated. The production of dry nanofibers by the 17-emitter array is estimated at 33.0 mg min-1 (1.38 mg min-1 per mm of active length), which compares favorably with the reported multiplexed electrospinning arrays with emitters distributed along a line.

  12. Preparation of Free Standing Carbon Nanofiber Electrodes for Supercapacitor Applications

    Science.gov (United States)

    Perananthan, Sahila

    Supercapacitors, also known as electrochemical double layer capacitors (EDLCs), are promising energy storage devices that can store more energy per unit volume or unit mass than the conventional capacitor. Supercapacitors can be charged and discharged at faster rates than batteries. Supercapacitors have extremely good cyclability; however, their low energy density compared to batteries limits their application. Due to their high conductivity, freestanding nature, and high surface area, electrospun porous carbon nanofibers can be used as electrode materials in supercapacitor devices. Operational voltage is another important factor affecting the performance of the supercapacitor. Constant effort has been made to improve energy density through developing materials with larger surface areas. Performance of the supercapacitor is improved by obtaining high surface area carbon fiber electrode materials using pore forming agents with polyacrylonitrile (PAN) and copolymer, polyacrylonitrile-1-vinylimidazole (PAN-VIM). Chapter 1 gives a general introduction on EDLCs, preparation of carbon nanofibers from polymer precursor using electrospinning process and thermal treatments. Chapter 2 describes the preparation of high surface area carbon electrode material from polyacrylonitrile (PAN) incorporating tetramethylammonium oxalate as a porogen. Chapter 3 shows the use of a porogen ammonium bicarbonate (ABC) to make high surface area carbon electrodes using the copolymer polyacrylonitrile - 1-vinylimidazole (PAN-VIM) as the precursor polymer. Chapter 4 describes the preparation and characterizations of electrode materials by electrospinning immiscible polymers blends of PAN-Polystyrene (PS) followed by thermal treatments. Chapter 5 compares the supercapacitor performances of PAN- poly(styrene-co-acrylonitrile) (PAN-SAN) and PAN-PS.

  13. Non-woven and aligned electrospun multicomponent luminescent polymer nanofibers: effects of aggregated morphology on the photophysical properties

    International Nuclear Information System (INIS)

    Wang, Cheng-Ting; Kuo, Chi-Ching; Chen, Hsieh-Chih; Chen, Wen-Chang

    2009-01-01

    In this paper, the morphology and photophysical properties of non-woven and aligned ES nanofibers prepared from the ternary blends of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) / poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV) / poly(methyl methacrylate) (PMMA) using a single-capillary spinneret are reported. Various PFO and DB-PPV phase-separated structures in the ES nanofibers were found by two different solvents: ellipsoidal DB-PPV (10-40 nm) and fiber-like PFO (20-40 nm) in the PMMA using chloroform, while fiber-like DB-PPV (10-20 nm) and fiber-like PFO (20-30 nm) using chlorobenzene. Such different PFO and DB-PPV structures resulted in various energy transfer/emission colors in the ES nanofibers. Moreover, highly aligned luminescence PFO/DB-PPV/PMMA blend ES nanofibers prepared from chlorobenzene showed a much higher polarized emission than the non-woven and the emission colors changed from blue to greenish-blue to green as the DB-PPV composition increased. The different polarized emission characteristics between PFO and DB-PPV in the ES nanofibers also led to varied emission colors at different angles. The present study suggests the morphologies and emission characteristics of the multicomponent ES nanofibers could be efficiently tuned through solvent types and blend ratios of semiconducting polymers.

  14. Non-woven and aligned electrospun multicomponent luminescent polymer nanofibers: effects of aggregated morphology on the photophysical properties.

    Science.gov (United States)

    Wang, Cheng-Ting; Kuo, Chi-Ching; Chen, Hsieh-Chih; Chen, Wen-Chang

    2009-09-16

    In this paper, the morphology and photophysical properties of non-woven and aligned ES nanofibers prepared from the ternary blends of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) / poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV) / poly(methyl methacrylate) (PMMA) using a single-capillary spinneret are reported. Various PFO and DB-PPV phase-separated structures in the ES nanofibers were found by two different solvents: ellipsoidal DB-PPV (10-40 nm) and fiber-like PFO (20-40 nm) in the PMMA using chloroform, while fiber-like DB-PPV (10-20 nm) and fiber-like PFO (20-30 nm) using chlorobenzene. Such different PFO and DB-PPV structures resulted in various energy transfer/emission colors in the ES nanofibers. Moreover, highly aligned luminescence PFO/DB-PPV/PMMA blend ES nanofibers prepared from chlorobenzene showed a much higher polarized emission than the non-woven and the emission colors changed from blue to greenish-blue to green as the DB-PPV composition increased. The different polarized emission characteristics between PFO and DB-PPV in the ES nanofibers also led to varied emission colors at different angles. The present study suggests the morphologies and emission characteristics of the multicomponent ES nanofibers could be efficiently tuned through solvent types and blend ratios of semiconducting polymers.

  15. Nanoscratch technique for aligning multiwalled carbon nanotubes ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 4. Nanoscratch technique for aligning multiwalled carbon nanotubes synthesized by the arc discharge method in open air. A Joseph ... The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs.

  16. Enhanced piezoresponse of highly aligned electrospun poly(vinylidene fluoride) nanofibers

    Science.gov (United States)

    Kang, Sung Bum; Won, Sang Hyuk; Im, Min Ji; Kim, Chan Ul; Park, Won Il; Baik, Jeong Min; Choi, Kyoung Jin

    2017-09-01

    Well-ordered nanostructure arrays with controlled densities can potentially improve material properties; however, their fabrication typically involves the use of complicated processing techniques. In this work, we demonstrate a uniaxial alignment procedure for fabricating poly(vinylidene fluoride) (PVDF) electrospun nanofibers (NFs) by introducing collectors with additional steps. The mechanism of the observed NF alignment, which occurs due to the concentration of lateral electric field lines around collector steps, has been elucidated via finite-difference time-domain simulations. The membranes composed of well-aligned PVDF NFs are characterized by a higher content of the PVDF β-phase, as compared to those manufactured from randomly orientated fibers. The piezoelectric energy harvester, which was fabricated by transferring well-aligned PVDF NFs onto flexible substrates with Ag electrodes attached to both sides, exhibited a 2-fold increase in the output voltage and a 3-fold increase in the output current as compared to the corresponding values obtained for the device manufactured from randomly oriented NFs. The enhanced piezoresponse observed for the aligned PVDF NFs is due to their higher β-phase content, denser structure, smaller effective radius of curvature during bending, greater applied strain, and higher fraction of contributing NFs.

  17. 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

  18. Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

    Science.gov (United States)

    Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

    2018-02-23

    Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. CoSn/carbon composite nanofibers for applications as anode in lithium-ion batteries

    International Nuclear Information System (INIS)

    Lu, Weili; Luo, Chenghao; Li, Yu; Feng, Yiyu; Feng, Wei; Zhao, Yunhui; Yuan, Xiaoyan

    2013-01-01

    CoSn/carbon composite nanofibers were prepared by electrospinning followed by heat treatment. Uniform morphologies and microstructures were observed by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction. The results demonstrated that well-dispersed nanoparticles of CoSn intermetallic compound and Sn with diameter of about 30–50 nm embedded in carbon nanofibers were prepared after carbonization at 850 °C. Compared with pure carbon nanofibers without the nanoparticles, CoSn/carbon composite nanofibers showed a high reversible capacity and excellent cycling performance, resulting from the formation of CoSn intermetallic nanoparticles and buffering by the carbon nanofiber matrix. The nanofiber mats with good flexibility were utilized as anodes in lithium-ion batteries, and the CoSn/carbon composite nanofibers exhibited a good fibrous morphology after the discharge/charge processes. Results indicated that electrospinning could be a feasible method to prepare Co–Sn–C composite nanofibers as anodes in lithium-ion batteries

  20. 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

    2017-04-18

    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

  1. Modified Filamentous Bacteriophage as a Scaffold for Carbon Nanofiber.

    Science.gov (United States)

    Szot-Karpińska, Katarzyna; Golec, Piotr; Leśniewski, Adam; Pałys, Barbara; Marken, Frank; Niedziółka-Jönsson, Joanna; Węgrzyn, Grzegorz; Łoś, Marcin

    2016-12-21

    With the advent of nanotechnology, carbon nanomaterials such as carbon nanofibers (CNF) have aroused substantial interest in various research fields, including energy storage and sensing. Further improvement of their properties might be achieved via the application of viral particles such as bacteriophages. In this report, we present a filamentous M13 bacteriophage with a point mutation in gene VII (pVII-mutant-M13) that selectively binds to the carbon nanofibers to form 3D structures. The phage-display technique was utilized for the selection of the pVII-mutant-M13 phage from the phage display peptide library. The properties of this phage make it a prospective candidate for a scaffold material for CNFs. The results for binding of CNF by mutant phage were compared with those for maternal bacteriophage (pVII-M13). The efficiency of binding between pVII-mutant-M13 and CNF is about 2 orders of magnitude higher compared to that of the pVII-M13. Binding affinity between pVII-mutant-M13 and CNF was also characterized using atomic force microscopy, scanning electron microscopy, and transmission electron microscopy, which confirmed the specificity of the interaction of the phage pVII-mutant-M13 and the CNF; the binding occurs via the phage's ending, where the mutated pVII protein is located. No similar behavior has been observed for other carbon nanomaterials such as graphite, reduced graphene oxide, single-walled carbon nanotubes, and multiwalled carbon nanotubes. Infrared spectra confirmed differences in the interaction with CNF between the pVII-mutant-M13 and the pVII-M13. Basing on conducted research, we hypothesize that the interactions are noncovalent in nature, with π-π interactions playing the dominant role. Herein, the new bioconjugate material is introduced.

  2. 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.

  3. Electrospinning in Situ Synthesis of Graphene-Doped Porous Copper Indium Disulfide/Carbon Composite Nanofibers for Highly Efficient Counter Electrode in Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    He, Jianxin; Zhou, Mengjuan; Wang, Lidan; Zhao, Shuyuan; Wang, Qian; Ding, Bin; Cui, Shizhong

    2016-01-01

    Highlights: • P-GN@CuInS 2(*) /C nanofibers were fabricated via electrospinning, in situ synthesis. • CuInS 2 nanocrystals were uniformly anchored in wrapped RGO to form nanofiber structure. • P-GN@CuInS 2 /C nanofibers exhibited porous and 3D superfine fiber morphology. • Graphene nanosheets led well-dispersed growth of CuInS 2 nanocrystals in nanofibers. • DSSC assembled using p-GN@CuInS 2 /C CE delivered a conversion efficiency of 7.23%. - Abstract: Porous graphene-doped copper indium disulfide/carbon (p-GN@CuInS 2 /C) composite nanofibers were fabricated via electrospinning, in situ synthesis, and carbonization. A polyacrylonitrile (PAN) solution containing graphene oxide nanosheets, copper dichloride (CuCl 2 ), indium trichloride (InCl 3 ), and thiourea (Tu.) in a mixed solvent of N,N-dimethylformamide/trichloromethane (DMF/CF) was used as the precursor solution for electrospinning. The resulting porous GN@CuInS 2 /C nanofibers were 107 ± 24 nm in diameter, and graphene nanosheets anchored with chalcopyrite CuInS 2 nanocrystals 7–12 nm in diameter were overlapped and embedded in the carbon matrix, aligning along the fiber axial direction. The Brunauer–Emmett–Teller (BET) surface area of the p-GN@CuInS 2 /C composite nanofibers was 795 m 2 /g, with a total pore volume of 0.71 cm 3 /g. These values were significantly larger than those of the sample without graphene and CuInS 2 /C nanofibers. A dye-sensitized solar cell (DSSC) assembled using the p-GN@CuInS 2 /C nanofibers as the counter electrode (CE) delivered a photoelectric conversion efficiency of 7.23%, which was higher than the efficiencies of DSSCs assembled using the samples without graphene (6.48%) and with the CuInS 2 /C nanofibers (5.45%). It was also much higher than that of the DSSC with a Pt CE (6.34%). The excellent photoelectric performance of the p-GN@CuInS 2 /C CE was attributed to its special hierarchical porous structure, which facilitated permeation of the liquid

  4. Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study.

    Science.gov (United States)

    Gergin, İlknur; Ismar, Ezgi; Sarac, A Sezai

    2017-01-01

    In this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

  5. 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.

  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. 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.

  8. Collagen-PVA aligned nanofiber on collagen sponge as bi-layered scaffold for surface cartilage repair.

    Science.gov (United States)

    Lin, Hsin-Yi; Tsai, Wen-Chi; Chang, Shih-Hsing

    2017-05-01

    Researchers have made bi-layered scaffolds but mostly for osteochondral repairs. The anatomic structure of human cartilage has different zones and that each has varying matrix morphology and mechanical properties is often overlooked. Two bi-layered collagen-based composites were made to replicate the superficial and transitional zones of an articular cartilage. Aligned and random collagen-PVA nanofibers were electrospun onto a freeze-dried collagen sponge to make the aligned and random composites, respectively. The morphology, swelling ratio, degradation and tensile properties of the two composites were examined. Primary porcine chondrocytes were cultured on the composites for three weeks and their proliferation and secretion of glycosaminoglycan (GAG) and type II collagen were measured. The influences of the cell culture on the tensile properties of the composites were studied. The nanofiber layer remained adhered to the sponge after three weeks of cell culture. Both composites lost 30-35% of their total weight in a saline buffer after three weeks. The tensile strength and Young's modulus of both composites increased after three weeks of chondrocyte culture (p collagen. They were seen embedded in lacunae after three weeks. The aligned composite may be more suitable for articular cartilage repair because of the higher tensile strength from the aligned nanofibers on the surface that can better resist wear.

  9. Aligned electrospun nanofibers as proton conductive channels through thickness of sulfonated poly (phthalazinone ether sulfone ketone) proton exchange membranes

    Science.gov (United States)

    Gong, Xue; He, Gaohong; Wu, Yao; Zhang, Shikai; Chen, Bo; Dai, Yan; Wu, Xuemei

    2017-08-01

    A novel approach is proposed to fabricate sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) proton exchange membranes with ordered through-plane electrospinning nanofibers, which provide nano-scale through-plane proton conductive channels along the thickness direction of the membranes, aiming to satisfy the challenging requirement of high through-plane proton conductivity in fuel cell operations. Induced by electrostatic attraction of strong electric field, the negatively charged sulfonic acid groups tend to aggregate towards surface of the electrospun fibers, which is evidenced by TEM and SAXS and further induces aggregation of the sulfonic acid groups in the SPPESK inferfiber voids filler along the surface of the nanofibers. The aligned electrospun nanofibers carries long-range ionic clusters along the thickness direction of the membrane and results in much higher total through-plane conductivity in the thickness aligned electrospun membranes, nearly twice as much as that of the cast SPPESK membrane. With smooth treatment, the thickness aligned electrospun SPPESK membranes exhibit higher single cell power density and tensile strength as compared with Nafion 115 (around 1.2 and 1.5 folds, respectively). Such a design of thickness aligned nano-size proton conductive channels provide feasibility for high performance non-fluorinated PEMs in fuel cell applications.

  10. CHARACTERIZATION OF CARBON NANOFIBERS/ ZrO 2 CERAMIC MATRIX COMPOSITE

    Czech Academy of Sciences Publication Activity Database

    Duszová, A.; Morgiel, J.; Bastl, Zdeněk; Mihály, J.; Dusza, J.

    2013-01-01

    Roč. 58, č. 2 (2013), s. 459-463 ISSN 1733-3490 Institutional support: RVO:61388955 Keywords : carbon nanofibers * nanocomposites * transmission electron microscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.763, year: 2013

  11. Characterization of polyacrylonitrile based carbon nanofiber mats via electron beam processing.

    Science.gov (United States)

    Kim, Du-Yeong; Shin, Hye-Kyoung; Jeun, Joon-Pyo; Kim, Hyun-Bin; Oh, Seung-Hwan; Kang, Phil-Hyun

    2012-07-01

    The aim of this study was to evaluate the ability of electron beam irradiation to drive stabilization reactions within PAN nanofiber mats to obtain carbon nanofiber mats. PAN nanofiber mats with fiber diameters of 300-400 nm were prepared via an electrospinning method. Electrospun PAN nanofiber mats were stabilized by electron beam irradiation with various doses up to 5,000 kGy. Using the irradiation-stabilized PAN nanofiber mats, carbon nanofibers were obtained by pyrolysis in a tube furnace for 1 h at 1,000 degrees C under an N2 atmosphere. FT-IR analysis indicated that the transformation of C[triple bond]N groups to C==N groups was accelerated by electron beam stabilization. The thermal behavior of the PAN nanofiber mats was studied using DSC and TGA. DSC thermograms showed that the peak temperatures of the exothermic reactions were found to decrease with increasing electron beam irradiation doses. Irradiation-stabilized PAN nanofiber mats were not observed to dramatically decrease in weight between 290 degrees C and 320 degrees C, an observation presumed to be related to cyclization. The char yields of PAN were found to increase with increasing irradiation doses.

  12. 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.

  13. Characterization of Plasma Synthesized Vertical Carbon Nanofibers for Nanoelectronics Applications

    Science.gov (United States)

    Lee, Jaesung; Feng, Philip X.-L.; Kaul, Anupama B.

    2013-01-01

    We report on the material characterization of carbon nanofibers (CNFs) which are assembled into a three-dimensional (3D) configuration for making new nanoelectromechanical systems (NEMS). High-resolution scanning electron microscopy (SEM) and x-ray electron dispersive spectroscopy (XEDS) are employed to decipher the morphology and chemical compositions of the CNFs at various locations along individual CNFs grown on silicon (Si) and refractory nitride (NbTiN) substrates, respectively. The measured characteristics suggest interesting properties of the CNF bodies and their capping catalyst nanoparticles, and growth mechanisms on the two substrates. Laser irradiation on the CNFs seems to cause thermal oxidation and melting of catalyst nanoparticles. The structural morphology and chemical compositions of the CNFs revealed in this study should aid in the applications of the CNFs to nanoelectronics and NEMS.

  14. Fabrication of ultra thin and aligned carbon nanofibres from ...

    Indian Academy of Sciences (India)

    Keywords. Nanofibres; carbon; nanotechnology; oxidation; aligned. Abstract. 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 ...

  15. 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.

  16. Effect of Carbon Nanofiber-Matrix Adhesion on Polymeric Nanocomposite Properties—Part II

    Directory of Open Access Journals (Sweden)

    Khalid Lafdi

    2008-01-01

    carbon nanocomposite. Carbon nanofibers were subjected to electrochemical oxidation in 0.1 M nitric acid for varying times. The strength of adhesion between the nanofiber and an epoxy matrix was characterized by flexural strength and modulus. The surface functional groups formed and their concentration of nanofibers showed a dependence on the degree of oxidation. The addition of chemical functional groups on the nanofiber surface allows them to physically and chemically adhere to the continuous resin matrix. The chemical interaction with the continuous epoxy matrix results in the creation of an interphase region. The ability to chemically and physically interact with the epoxy region is beneficial to the mechanical properties of a carbon nanocomposite. A tailored degree of surface functionalization was found to increase adhesion to the matrix and increase flexural modulus.

  17. Interactions of gold nanoparticles with the interior of hollow graphitized carbon nanofibers.

    Science.gov (United States)

    La Torre, Alessandro; Fay, Michael W; Rance, Graham A; Del Carmen Gimenez-Lopez, Maria; Solomonsz, William A; Brown, Paul D; Khlobystov, Andrei N

    2012-04-23

    Interactions of free-standing gold nanoparticles and hollow graphitized nanofibers in colloidal suspension are investigated, revealing the first example of the controlled arrangement of nanoparticles inside nano-containers, as directed by their internal structure. The ordering is highly effective for small gold nanoparticles whose sizes are commensurate with the height of graphitic step-edges in the graphitized carbon nanofibers and is less effective for larger gold nanoparticles. Studies aimed at understanding the role of the organic-solvent surface tension, employed for the filling experiments, demonstrate that gold nanoparticles become preferentially anchored into the hollow graphitized carbon nanofibers under a mixture of pentane/CO(2) in supercritical conditions. It is shown that a three-step cleaning procedure enables effective removal of gold nanoparticles adsorbed on the exterior surface of graphitized carbon nanofibers, while ordered arrays of encapsulated nanoparticles are retained. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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.

  19. Fabrication and characterization of vitamin B5 loaded poly (l-lactide-co-caprolactone)/silk fiber aligned electrospun nanofibers for schwann cell proliferation.

    Science.gov (United States)

    Bhutto, M Aqeel; Wu, Tong; Sun, Binbin; Ei-Hamshary, Hany; Al-Deyab, Salem S; Mo, Xiumei

    2016-08-01

    Bioengineering strategies for peripheral nerve regeneration have been focusing on the development of alternative treatments for nerve repair. In present study we have blended the Vitamin B5 (50mg) with 8% P(LLA-CL) and P(LLA-CL)/SF solutions and produced aligned electrospun nanofiber mashes and characterized the material for its physiochemical and mechanical characteristics. The vitamin loaded composites nanofibers showed tensile strength of 8.73±1.38 and 8.4±1.37 in P(LLA-CL)/Vt and P(LLA-CL)/SF/Vt nanofibers mashes, respectively. By the addition of vitamin B5 the P(LLA-CL) nanofibers become hydrophilic and the contact angle decreased from 96° to 0° in 6min of duration. The effect of vitamin B5 on Schwann cells proliferation and viability were analyzed by using MTT assay and the number of cells cultured on vitamin loaded nanofiber mashes was significantly higher than the without vitamin loaded nanofiber samples after 5th day (pvitamin release behavior was observed in PBS solution and released vitamin was calculated by revers phase HPLC method. The sustain release behavior of vitamin B5 were noted higher in P(LLA-CL)/Vt (80%) nanofibers as compared to P (LLA-CL)/SF/Vt (62%) nanofibers after 24h. The present work provided a basis for further studies of this novel aligned nanofibrous material in nerve tissue repair or regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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.

  1. 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.

  2. Electrospun Carbon Nanofiber Membranes for Filtration of Nanoparticles from Water

    Directory of Open Access Journals (Sweden)

    Mirko Faccini

    2015-01-01

    Full Text Available Nowadays, hundreds of consumer products contain metal and metal oxide nanoparticles (NP; this increases the probability of such particles to be released to natural waters generating a potential risk to human health and the environment. This paper presents the development of efficient carboneous nanofibrous membranes for NP filtration from aqueous solutions. Free-standing carbon nanofiber (CNF mats with different fiber size distribution ranging from 126 to 554 nm in diameter were produced by electrospinning of polyacrylonitrile (PAN precursor solution followed by thermal treatment. Moreover, tetraethoxyorthosilicate was added to provide flexibility and increase the specific surface area of the CNF. The resulting membranes are bendable and mechanically strong enough to withstand filtration under pressure or vacuum. The experimental results of filtration revealed that the fabricated membranes could efficiently reject nanoparticles of different types (Au, Ag, and TiO2 and size (from 10 to 100 nm in diameter from aqueous solutions. It is worth mentioning that the removal of Ag NP with diameters as small as 10 nm was close to 100% with an extremely high flux of 47620 L m−2 h−1 bar−1.

  3. Design of carbon nanofiber embedded conducting epoxy resin

    International Nuclear Information System (INIS)

    Gantayat, Subhra; Sarkar, Niladri; Rout, Dibyaranjan; Swain, Sarat K.

    2017-01-01

    Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

  4. Design of carbon nanofiber embedded conducting epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Gantayat, Subhra [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Sarkar, Niladri [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); Rout, Dibyaranjan [School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Swain, Sarat K., E-mail: swainsk2@yahoo.co.in [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India)

    2017-01-15

    Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

  5. 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.

  6. 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.

  7. Comparative study of cellulose nanofiber and carbon nanofiber effects as reinforcement fillers on mechanical properties of polypropylene composites

    Science.gov (United States)

    Ghaemi, Ferial; Tahir, Paridah Md; Abdullah, Luqman Chuah; Kargarzadeh, Haniyeh

    2017-12-01

    Cellulose nanofiber (CNF1) as natural fiber and carbon nanofiber (CNF2) as synthetic fiber were used as reinforcement fillers in polypropylene (PP) polymer to improve the mechanical properties of the composite. The CNF1 was produced from Kenaf bast fibers by use of mechanical method and the CNF2 was synthesized by use of chemical vapor deposition (CVD) technique. The produced fillers were dispersed into polypropylene, to manufacture nanocomposites (CNF1/PP and CNF2/PP). Analysis and comparison were made on the effects of the natural fibers with synthetics fibers having the same size and dimension, on the properties of polymer matrix. The characteristics of the CNF1 and CNF2 such as morphology, structure and composition were studied through SEM, TEM and EDX. Tensile test is used to evaluate the mechanical properties of the produced nanocomposites.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    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

  9. Carbon nanofibers grown on activated carbon fiber fabrics as electrode of supercapacitors

    International Nuclear Information System (INIS)

    Ko, T-H; Hung, K-H; Tzeng, S-S; Shen, J-W; Hung, C-H

    2007-01-01

    Carbon nanofibers (CNFs) were grown directly on activated carbon fiber fabric (ACFF), which was then used as the electrode of supercapacitors. Cyclic voltammetry and ac impedance were used to characterize the electrochemical properties of ACFF and CNF/ACFF electrodes in both aqueous and organic electrolytes. ACFF electrodes show higher specific capacitance than CNF/ACFF electrodes due to larger specific surface area. However, the spaces formed between the CNFs in the CNF/ACFF electrodes are more easily accessed than the slit-type pores of ACFF, and much higher electrical-double layer capacitance was obtained for CNF/ACFF electrodes

  10. Graphitic Carbon Nitride/Nitrogen-Rich Carbon Nanofibers: Highly Efficient Photocatalytic Hydrogen Evolution without Cocatalysts.

    Science.gov (United States)

    Han, Qing; Wang, Bing; Gao, Jian; Qu, Liangti

    2016-08-26

    An interconnected framework of mesoporous graphitic-C3 N4 nanofibers merged with in situ incorporated nitrogen-rich carbon has been prepared. The unique composition and structure of the nanofibers as well as strong coupling between the components endow them with efficient light-harvesting properties, improved charged separation, and a multidimensional electron transport path that enhance the performance of hydrogen production. The as-obtained catalyst exhibits an extremely high hydrogen-evolution rate of 16885 μmol h(-1)  g(-1) , and a remarkable apparent quantum efficiency of 14.3 % at 420 nm without any cocatalysts, which is much higher than most reported g-C3 N4 -based photocatalysts even in the presence of Pt-based cocatalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Shape-Controlled Synthesis of Ni-Based Nanoparticles and Patterning for Carbon Nanofiber Growth

    Science.gov (United States)

    Sarac, Mehmet Fahri

    This dissertation reviews a comprehensive set of research results comprised of three studies, which includes the synthesis of nickel (Ni) nanoparticles (NPs) and their conversion chemistry, methods for depositing them onto substrates, and catalysis of carbon nanofiber growth. The first part of the work is concerned with the synthesis of Ni NPs, dropcasting and growing them in alignment with carbon nanofibers along a silicon (Si) substrate. Following observed success of this step, Ni NPs were airbrushed across different substrates, attempting to observe differences while reporting the results of an extensive comparative analysis of the different substrates used. Here, it was observed that the Ni NPs had a tendency to have dendritic rather than spherical shapes, motivating an additional study of the cause of branching and how it can be controlled. All three portions of this study are presented and discussed in detail. In the first set of experiments, vertically aligned carbon nanofibers (VACNFs) were created through ligand-stabilized Ni nanoparticle (NP) catalysts and plasma enhanced chemical vapor deposition; these NPs were used to allow growth of VACNFs in dense arrays. In the pregrowth heating process, the ligands are converted into graphitic shells that prevent agglomeration and coalescence of the catalyst NPs, resulting in a monodisperse VACNF size distribution. Meanwhile, VACNFs were grown from Ni NPs that had been airbrushed onto various substrates (silicon (Si), aluminum (Al), copper (Cu), and titanium (Ti)). Si micropowder was also used as a precursor for Si coatings formed in situ on VACNFs, causing rigidity. Growth of VACNFs on metal foils will facilitate applications that require thermal or electrical contact to the VACNFs, such as anode materials for Li-ion batteries and thermal interface materials. A related study focused on the synthesis of Ni3C1-x NPs, the control of branching in dendritic Ni3C1-x NPs and the effect of branching on the conversion into

  12. 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

    it possible to avoid a loss of sensitivity because of the diffusion of the sample. The obtained results showed that the peptide nanofibers were suitable as a cell culturing substrate for PC12 cells. The peptide nanofibers could be employed as an alternative biological material to increase the adherence...

  13. Synthesis of carbon nanofibers on impregnated powdered activated carbon as cheap substrate

    Directory of Open Access Journals (Sweden)

    A.A. Mamun

    2016-07-01

    Full Text Available The catalysis and characterization of carbon nanofibers (CNFs composite are reported in this work. Carbon nanofibers were produced on oil palm shell powdered activated carbon (PAC, which was impregnated with nickel. Chemical Vapor Deposition (CVD of C2H2 was used in the presence of hydrogen at ∼650 °C. The flow rates of carbon source and hydrogen were fixed. The CNFs formed directly on the surface of the impregnated PAC. Variable weight percentages (1%, 3%, 5%, 7% and 9% of the catalyst salt (Ni+2 were used for the impregnation. However, the best catalysis was observed on the substrate with 3% Ni+2. The product displayed a relatively high surface area, essentially constituted by the external surface. New functional groups also appeared compared to those in the PAC. Field Emission Scanning Microscopy (FESEM, Transmission Electron Microscopy (TEM, Fourier Transform Infrared (FTIR, BET surface area analysis and energy dispersive X-ray (EDX were used for the characterization of the new carbon nano product, which was produced through a clean novel process.

  14. 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

    2012-05-11

    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.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    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 m 2 (700 ft 2 ) 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. (paper)

  16. 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.

  17. 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.

  18. 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.

  19. Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO: a spectroscopic and electrochemical study

    Directory of Open Access Journals (Sweden)

    İlknur Gergin

    2017-08-01

    Full Text Available In this study, a precursor for carbon nanofibers (CNF was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

  20. Microporous Carbon Polyhedrons Encapsulated Polyacrylonitrile Nanofibers as Sulfur Immobilizer for Lithium-Sulfur Battery.

    Science.gov (United States)

    Zhang, Ye-Zheng; Wu, Zhen-Zhen; Pan, Gui-Ling; Liu, Sheng; Gao, Xue-Ping

    2017-04-12

    Microporous carbon polyhedrons (MCPs) are encapsulated into polyacrylonitrile (PAN) nanofibers by electrospinning the mixture of MCPs and PAN. Subsequently, the as-prepared MCPs-PAN nanofibers are employed as sulfur immobilizer for lithium-sulfur battery. Here, the S/MCPs-PAN multicomposites integrate the advantage of sulfur/microporous carbon and sulfurized PAN. Specifically, with large pore volume, MCPs inside PAN nanofibers provide a sufficient sulfur loading. While PAN-based nanofibers offer a conductive path and matrix. Therefore, the electrochemical performance is significantly improved for the S/MCPs-PAN multicomposite with a suitable sulfur content in carbonate-based electrolyte. At the current density of 160 mA g -1 sulfur , the S/MPCPs-PAN composite delivers a large discharge capacity of 789.7 mAh g -1 composite , high Coulombic efficiency of about 100% except in the first cycle, and good capacity retention after 200 cycles. In particular, even at 4 C rate, the S/MCPs-PAN composite can still release the discharge capacity of 370 mAh g -1 composite . On the contrary, the formation of the thick SEI layer on the surface of nanofibers with a high sulfur content are observed, which is responsible for the quick capacity deterioration of the sulfur-based composite in carbonate-based electrolyte. This design of the S/MCPs-PAN multicomposite is helpful for the fabrication of stable Li-S battery.

  1. SYNTHESIS AND APPLICATION OF HIGH-QUALITY CARBON NANOFIBERS TO INCREASE THE PERFORMANCE OF AIRCRAFT PARTS

    Directory of Open Access Journals (Sweden)

    Hamid Reza Shahverdi

    2017-01-01

    Full Text Available Modern carbon nanofibers (CNF, obtained from polyacrylonitrile (PAN, do not have high tensile strength. It is because there is still no understanding how the electroforming method affects the quality of CNF.This paper investigates a process to obtain high-strength nanofibers with a carbon content of up to 90% by the method of electroforming. The research made it possible to obtain CNFs with a diameter of 150-500 nm with uniqueproperties due to our CNF continuous and combined forms, which distinguishes our CNFs from existing ones when appliedto composite materials. Such nanofibers, obtained by selecting the optimum stabilization temperature and carbonization regime, have homogeneous cross sections, and as a result of improving their mechanical properties, the aircraft structure performance can be substantially improved.

  2. Moisture condensation behavior of hierarchically carbon nanotube-grafted carbon nanofibers.

    Science.gov (United States)

    Park, Kyu-Min; Lee, Byoung-Sun; Youk, Ji Ho; Lee, Jinyong; Yu, Woong-Reol

    2013-11-13

    Hierarchical micro/nanosurfaces with nanoscale roughness on microscale uneven substrates have been the subject of much recent research interest because of phenomena such as superhydrophobicity. However, an understanding of the effect of the difference in the scale of the hierarchical entities, i.e., nanoscale roughness on microscale uneven substrates as opposed to nanoscale roughness on (a larger) nanoscale uneven surface, is still lacking. In this study, we investigated the effect of the difference in scale between the nano- and microscale features. We fabricated carbon nanotube-grafted carbon nanofibers (CNFs) by dispersing a catalyst precursor in poly (acrylonitrile) (PAN) solution, electrospinning the PAN/catalyst precursor solution, carbonization of electrospun PAN nanofibers, and direct growth of carbon nanotubes (CNTs) on the CNFs. We investigated the relationships between the catalyst concentrations, the size of catalyst nanoparticles on CNFs, and the sizes of CNFs and CNTs. Interestingly, the hydrophobic behavior of micro/nano and nano/nano hierarchical surfaces with water droplets was similar; however a significant difference in the water condensation behavior was observed. Water condensed into smaller droplets on the nano/nano hierarchical surface, causing it to dry much faster.

  3. Finite element analysis of in-situ alignment of nanoparticles in polymeric nanofibers using magnetic field assisted electrospinning

    International Nuclear Information System (INIS)

    Jayaseelan, D; Biji, P

    2015-01-01

    In this study, a three-dimensional magnetic field assisted electrospinning (MFAES) system has been modeled to understand the correlation between the applied magnetic field and electric field distributions during nanoparticle alignment. The results reveal that the electric field distribution has been altered by positioning the magnets at the needle end. The analysis explored the possibility to create a stable liquid jet under a magnetic field, which allows the formation of organized nanostructures in nanofibers. The polarity of the magnet has been used to manipulate the electric field distribution in the electrospinning system. Based on the configuration of magnetic flux lines, the distribution of the electric field has been found to be altered. An axial magnetic field has been provided by the repulsive mode configuration, which could be the reason for alignment of nanoparticles during electrospinning. Simulation proved that the bending instability of the charged liquid jet can be efficiently controlled by placing the magnets on both sides of the fiber formation path in the electrospinning system. The impact of an axial magnetic field on nanofiber formation and nanoparticle alignment during the MFAES process was further experimentally validated. (paper)

  4. 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. © 2016 Wiley Periodicals, Inc.

  5. Direct growth of vertically aligned carbon nanotubes on silicon ...

    African Journals Online (AJOL)

    Vertically aligned carbon nanotubes have been synthesized by spray pyrolysis from Glycine max oil on silicon substrate using ferrocene as catalyst at 650 °C. Glycine max oil, a plant-based hydrocarbon precursor was used as a source of carbon and argon as a carrier gas. The as-grown vertically aligned carbon nanotubes ...

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

    Directory of Open Access Journals (Sweden)

    Vitaly Koissin

    2016-07-01

    Full Text Available 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 potentially advantageous for application in polymer-matrix composites. The fiber surface functional groups significantly change after the growth and this also potentially provides a better interfacial adhesion. These advantages can be controlled, e.g., by the catalyst loading and the type of solvent used for its deposition.

  7. 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.

  8. 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...

  9. Preparation and characterization of oriented poly(vinyl alcohol)/carbon nanotube composite nanofibers

    Science.gov (United States)

    Shimizu, Akikazu; Kato, Hayato; Sato, Taiga; Kushida, Masahito

    2017-07-01

    Oriented nanofiber mats blended with carbon nanotubes (CNTs) are expected to be applied as cell seeding scaffolds. Biomaterials that are often used for cell seeding scaffolds generally have low mechanical strength and low electrical conductivity; thus, it has been difficult to apply them to tissues such as heart and nerve. In this study, we prepared oriented poly(vinyl alcohol) (PVA) nanofiber mats blended with various CNT concentrations (up to 10 wt %) by electrospinning using the parallel plate electrodes as collectors with applied voltage. The morphology, mechanical properties, and electrical properties of the prepared oriented nanofiber mats were measured by using various techniques such as scanning electron microscopy (SEM). The tensile strength of the oriented nanofiber mats in the applied voltage direction increased from 2.5 to 9.7 MPa with CNT concentration. Furthermore, the electrical conductivity of the oriented nanofiber mats in the applied voltage direction increased from 0.67 × 10-7 to 4.3 × 10-7 S·m-1. Also, the mechanical strength and electrical conductivity of the oriented nanofiber mats in the applied voltage direction were 3-4 and 2-3 times higher than those in the perpendicular direction, respectively.

  10. 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

  11. Nickel/carbon nanofibers composite electrodes as supercapacitors prepared by electrospinning

    International Nuclear Information System (INIS)

    Li Jian; Liu, En-hui; Li Wen; Meng Xiangyun; Tan Songting

    2009-01-01

    Nickel-embedded carbon nanofibers were prepared by the processes of stabilization and carbonation after electrospinning a mixture solution of nickel acetate and polyacrylonitrile in N,N-dimethylformamide. The surface morphology and structure of composites were examined by scanning electron microscope (SEM) and X-ray diffraction (XRD). Compared with performances of composite electrodes with different mass ratios of nickel and carbon by cyclic voltammetry (CV) and chronopotentiogram test, the results show that the introduction of a proper proportion of nickel into carbon could enhance both specific capacitance (SC) and electrochemical stability. The specific capacitance of the carbon nanofiber electrode without the Ni loading was 50 F/g, while that of 22.4 wt.% Ni/carbon electrode increased to 164 F/g. The improved specific capacitance may be attributed to synergic effects from each pristine component, and the electrochemical catalysis effect of nickel.

  12. 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.

  13. 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.

  14. 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.

  15. Characterization of carbon nanofibers by SEM, TEM, ESCA and raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Tatarko, P.; Puchý, V.; Dusza, J.; Morgiel, J.; Bastl, Zdeněk; Mihály, J.

    2010-01-01

    Roč. 48, č. 6 (2010), s. 379-385 ISSN 0023-432X Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon micro/nanofiber * cylindrical fiber * bambo-shaped fiber Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.471, year: 2010

  16. 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

  17. 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.

  18. Hollow carbon-nanotube/carbon-nanofiber hybrid anodes for Li-ion batteries.

    Science.gov (United States)

    Chen, Yuming; Li, Xiaoyan; Park, Kyusung; Song, Jie; Hong, Jianhe; Zhou, Limin; Mai, Yiu-Wing; Huang, Haitao; Goodenough, John B

    2013-11-06

    By a novel in situ chemical vapor deposition, activated N-doped hollow carbon-nanotube/carbon-nanofiber composites are prepared having a superhigh specific Brunauer–Emmett–Teller (BET) surface area of 1840 m(2) g(–1) and a total pore volume of 1.21 m(3) g(–1). As an anode, this material has a reversible capacity of ~1150 mAh g(–1) at 0.1 A g(–1) (0.27 C) after 70 cycles. At 8 A g(–1) (21.5 C), a capacity of ~320 mAh g(–1) fades less than 20% after 3500 cycles, which makes it a superior anode material for a Li-ion battery.

  19. The importance of interfacial resistance on the thermal behavior of carbon nanofiber/epoxy composites

    Science.gov (United States)

    Gardea, Frank; Naraghi, Mohammad; Lagoudas, Dimitris C.

    2014-04-01

    This research addresses the thermal transport in carbon nanofiber (CNF)/epoxy composites via finite element modeling. The effects of nanofiber orientation on thermal transport are investigated through Fourier's Law of heat conduction and through simulation of a high magnitude, short heat pulse. The effect of interface thermal resistance on the effective composite thermal conductivity is also quantified. In addition, a simplified lightning strike simulation is modeled in order to analyze the effect of interfacial thermal resistance on composite behavior when subjected to multiple short heat pulses.

  20. Dispersion and alignment of carbon nanotubes in polymer based composites

    Science.gov (United States)

    Camponeschi, Erin Lynn

    This research is intended to create usable carbon nanotube polymer based composites for structural applications by effectively aligning and dispersing the carbon nanotubes in a polymer matrix. The motivation for this research is to create very lightweight, high strength materials that will surpass their predecessors: carbon fibers. The final product then can be used in applications across the industries. This research determined the effect of three different surface-active agents and two different aligning methods on the structural features and mechanical properties of the polymer-based composite. The three types of surface-active agents used in this research are a surfactant and two different block copolymers. From this research, it will be determined how different surface-active agents adequately disperse the carbon nanotube, and the effects the dispersing agent have on a final dispersed product. In addition, the dispersing agent effects on the alignment of the carbon nanotubes and the final product can be compared. The two alignment techniques used in this research were alignment via shear flow and tethering iron oxide particles to the carbon nanotubes to induce alignment in a magnetic field. The method of shear aligning carbon nanotubes is very simplistic in theory, but actual application becomes much more challenging. This research illustrates the effects on shear alignment in a viscous polymer flow and then applies those theories to polymers. This work then compares the different alignment techniques to determine the overall increase of properties and the effective carbon nanotube alignment. This research provides a framework for the creation of dispersed and aligned composites that can be expanded upon and improved to further develop the carbon nanotubes as possible replacement fillers for composite materials.

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

    Science.gov (United States)

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

    2016-09-09

    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.

  2. Optical Second Harmonic Generation in the BaTiO3 phase of magnetically aligned multiferroic nanofibers

    Science.gov (United States)

    Gasperi, Katia

    Multiferroic materials enable the exploration of electrical control of magnetic properties and vice versa. Their increasing interest is especially due to their potential applications in the industry of information storage. Thanks to recent progress in nanotechnology, they have also been found to have many other applications such as transducers and sensors, and they already occupy a unique place in the biomedical field. The objective of this project is to study multiferroic nanofibers made of cobalt ferrite CoFe2O 4 (CFO) and barium titanate BaTiO3 (BTO) with a specific focus in the characterization of the ferroelectric phase. We researched the state of knowledge concerning the size effects on phase transition for nanoparticles and polycrystals BTO. The ferroelectric phase transition of BTO occurs when it changes from a tetragonal (anisotropic) crystal structure to a cubic (isotropic) structure. This change suggests that optical second harmonic generation (SHG) is a good measurement technique for monitoring the phase transition of the BTO half of the nanofibers. We designed and prepared a temperature dependent SHG experiment on magnetically aligned fibers in transmission with the possibility to investigate the polarization dependence of the signal. We also prepared interdigital electrodes on glass for the future study of the fibers in an external electric field.

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

    OpenAIRE

    Juan Carlos Calderón; Miguel Rios Ráfales; María Jesús Nieto-Monge; Juan Ignacio Pardo; Rafael Moliner; María Jesús Lázaro

    2016-01-01

    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 parti...

  4. Catalytically Graphitized Electrospun Carbon Nanofibers Adorned with Nickel Nanoparticles for Catalysis Applications

    Directory of Open Access Journals (Sweden)

    A. M. Bazargan

    2016-01-01

    Full Text Available Catalytically graphitized electrospun carbon nanofibers adorned uniformly with fine nickel nanoparticles were successfully prepared. The procedure was based on the electrospinning technique and the use of nickel precursor to create both graphitized nanofibers and nickel nanoparticles under a relatively low-temperature heat treatment. The X-ray diffraction and Raman results clearly proved catalytic graphitization of polymer-based carbon fibers in the presence of nickel catalyst. Taking the results from scanning and transmission electron microscopies and X-ray diffraction into account, it was inferred that during the heat treatment, nickel atoms have diffused through the nanofibers and formed fine nickel nanoparticles on the surface of graphitized nanofibers to make a well stabilized heterogeneous nanostructure. The results from Brunauer–Emmett–Teller technique also showed a high surface area value of 140.2 m2g-1 for the obtained structure. All these attributes along with the fibrous and porous structure enable the product to serve as a potential candidate in the catalysis applications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tiefeng; Ni, Dongjing; Chen, Xia; Wu, Fei; Ge, Pengfei; Lu, Wangyang, E-mail: luwy@zstu.edu.cn; Hu, Hongguang; Zhu, ZheXin; Chen, Wenxing, E-mail: wxchen@zstu.edu.cn

    2016-11-05

    Highlights: • A facile synthetic strategy to prepare visible-light responsive electrospun nanofibers. • Self-floating nanofiber photocatalyts for the effective utilization of solar. • Possible degradation pathway of RhB and CBZ under visible light and solar irradiation. • Present a method for removing highly hazardous contaminants. - Abstract: 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-C{sub 3}N{sub 4}/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C{sub 3}N{sub 4}/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-C{sub 3}N{sub 4}/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.

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

    Science.gov (United States)

    Adabi, Mahdi; Saber, Reza; Faridi-Majidi, Reza; Faridbod, Farnoush

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Nanoscratch technique for aligning multiwalled carbon nanotubes ...

    Indian Academy of Sciences (India)

    horizontally aligned high-quality MWCNTs using the arc discharge method with the help of a metal scraper in an open air. This technique is extended after removing the soot from the cathode; physical forces are applied manu- ally on the surface of the soot to align the MWCNTs along the direction of the application of the ...

  8. 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.

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

    International Nuclear Information System (INIS)

    Adabi, Mahdi; Saber, Reza; Faridi-Majidi, Reza; Faridbod, Farnoush

    2015-01-01

    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

  10. 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.

  11. 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. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electrostatically Induced Carbon Nanotube Alignment for Polymer Composite Applications

    Science.gov (United States)

    Chapkin, Wesley Aaron

    We have developed a non-invasive technique utilizing polarized Raman spectroscopy to measure changes in carbon nanotube (CNT) alignment in situ and in real time in a polymer matrix. With this technique, we have confirmed the prediction of faster alignment for CNTs in higher electric fields. Real-time polarized Raman spectroscopy also allows us to demonstrate the loss of CNT alignment that occurs after the electric field is removed, which reveals the need for fast polymerization steps or the continued application of the aligning force during polymerization to lock in CNT alignment. Through a study on the effect of polymer viscosity on the rate of CNT alignment, we have determined that shear viscosity serves as the controlling mechanism for CNT rotation. This finding matches literature modeling of rigid rod mobility in a polymer melt and demonstrates that the rotational mobility of CNTs can be explained by a continuum model even though the diameters of single-walled CNTs are 1-2 nm. The viscosity dependence indicates that the manipulation of temperature (and indirectly viscosity) will have a direct effect on the rate of CNT alignment, which could prove useful in expediting the manufacturing of CNT-reinforced composites cured at elevated temperatures. Using real-time polarized Raman spectroscopy, we also demonstrate that electric fields of various strengths lead not only to different speeds of CNT rotation but also to different degrees of alignment. We hypothesize that this difference in achievable alignment results from discrete populations of nanotubes based on their length. The results are then explained by balancing the alignment energy for a given electric field strength with the randomizing thermal energy of the system. By studying the alignment dynamics of different CNT length distributions, we show that different degrees of alignment achieved as a function of the applied electric field strength are directly related to the square of the nanotube length. This

  13. Synthesis of carbon nanofibers by catalytic CVD of chlorobenzene over bulk nickel alloy

    Science.gov (United States)

    Kenzhin, Roman M.; Bauman, Yuri I.; Volodin, Alexander M.; Mishakov, Ilya V.; Vedyagin, Aleksey A.

    2018-01-01

    Catalytic chemical vapor deposition (CCVD) of chlorobenzene over bulk nickel alloy (nichrome) was studied. The bulk Ni-containing samples being exposed to a contact with aggressive reaction medium undergo self-disintegration followed by growth of carbon nanofibers. This process, also known as a metal dusting, requires the simultaneous presence of chlorine and hydrogen sources in the reaction mixture. Molecule of chlorobenzene complies with these requirements. The experiments on CCVD were performed in a flow-through reactor system. The initial stages of nickel disintegration process were investigated in a closed system under Autogenic Pressure at Elevated Temperature (RAPET) conditions. Scanning and transmission electron microscopies and ferromagnetic resonance spectroscopy were applied to examine the samples after their interaction with chlorobenzene. Introduction of additional hydrogen into the flow-through system was shown to affect the morphology of grown carbon nanofibers.

  14. Controllable preparation of helical carbon nanofibers by CCVD method and their characterization

    Science.gov (United States)

    Jin, Yongzhong; Ren, Jiao; Chen, Jian; Dai, Zuyang; Li, Binghong; Zhou, Xuesong

    2018-01-01

    Helical carbon nanofibers (HCNFs) with the diameter less than 80 nm were produced through catalytic chemical vapor deposition by acetylene pyrolysis with a catalyst derived from the decomposition of copper tartrate at 270 °C. Thermogravimetric and differential scanning calorimetry, x-ray diffraction, atomic force microscopy, scanning electron microscopy and transmission electron microscope were used to characterize the reaction products. The results show that heating rate of copper tartrate has a significant effect on catalyst particle size and fiber morphology. Three different kinds of fiber morphologies can be obtained at the heating rate of 1–10 °C min‑1. The formation mechanism of carbon nanofibers indicates that catalyst particles with symmetric shape and small size were suitable for the growth of regular HCNFs.

  15. Preparation and Study on Nickel Oxide Reduction of Polyacrylonitrile-Based Carbon Nanofibers by Thermal Treatment.

    Science.gov (United States)

    Lee, Yeong Ju; Kim, Hyun Bin; Jeun, Joon Pyo; Lee, Dae Soo; Koo, Dong Hyun; Kang, Phil Hyun

    2015-08-01

    Carbon materials containing magnetic nanopowder have been attractive in technological applications such as electrochemical capacitors and electromagnetic wave shielding. In this study, polyacrylonitrile (PAN) fibers containing nickel nanoparticles were prepared using an electrospinning method and thermal stabilization. The reduction of nickel oxide was investigated under a nitrogen atmosphere within a temperature range of 600 to 1,000 °C. Carbon nanofibers containing nickel nanoparticles were characterized by FE-SEM, EDS, XRD, TGA, and VSM. It was found that nickel nanoparticles were formed by a NiO reduction in PAN as a function of the thermal treatment. These results led to an increase in the coercivity of nanofibers and a decrease in the remanence magnetization.

  16. Nanofiber containing carbon nanotubes enhanced PC12 cell proliferation and neuritogenesis by electrical stimulation.

    Science.gov (United States)

    Su, Wen-Ta; Shih, Yi-An

    2015-01-01

    The nervous system is an important regulator of the human body because it adapts our responses to the external environment and provides people the ability of thought, memory, and emotion. PC12 is a cell line that is commonly used to study the behavior of neural differentiation. PC12 cells further differentiate into nerve cells when stimulated by nerve growth factor (NGF), which have neurite, dendrite, and axon, and form synapses with neighboring cells to build neural networks. Micropatterns and electric stimulation can significantly influence cellular attachment, proliferation, orientation, extracellular matrix (ECM) expression, neural differentiation, and cellular motion. We fabricated polycaprolactone (PCL) nanofiber with or without carbon nanotubes (CNTs) by electrospinning and promoted the neural differentiation of PC12 cells by electric stimulation. We used scanning electron microscope (SEM) and fluorescence microscope to observe the NGF-induced growth of PC12 cells on PCL nanofiber. Axon formation and cellular activity expression, that confirm that PC12 cells can grow well on PCL nanofiber, and the gene expressions of MAP1b and GAP43 significantly increased after electric stimulation. Based on the results, the structure of nanofibers containing CNTs can effectively induce neural differentiation of PC12 cells in an electric field. This experimental model can be used for future clinical applications.

  17. 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.

  18. 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.

  19. Characterization of carbon nanofiber mats produced from electrospun lignin-g-polyacrylonitrile copolymer.

    Science.gov (United States)

    Youe, Won-Jae; Lee, Soo-Min; Lee, Sung-Suk; Lee, Seung-Hwan; Kim, Yong Sik

    2016-01-01

    The graft copolymerization of acrylonitrile (AN) onto methanol-soluble kraft lignin (ML) was achieved through a two-step process in which AN was first polymerized with an α,α'-azobisisobutyronitrile initiator, followed by radical coupling with activated ML. A carbon nanofiber material was obtained by electrospinning a solution of this copolymer in N,N-dimethylformamide, then subjecting it to a heat treatment including thermostabilization at 250°C and subsequent carbonization at 600-1400°C. Increasing the carbonization temperature was found to increase the carbon content of the resulting carbon nanofibers from 70.5 to 97.1%, which had the effect of increasing their tensile strength from 35.2 to 89.4 MPa, their crystallite size from 13.2 to 19.1 nm, and their electrical conductivity from ∼0 to 21.3 Scm(-1). The morphology of the mats, in terms of whether they experienced beading or not, was found to be dependent on the concentration of the initial electrospinning solution. From these results, it is proposed that these mats could provide the basis for a new class of carbon fiber material. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. 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.

  1. 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.

  2. Electrospun core-shell nanofibers derived Fe-S/N doped carbon material for oxygen reduction reaction

    Science.gov (United States)

    Guo, Junxia; Niu, Qijian; Yuan, Yichun; Maitlo, Inamullh; Nie, Jun; Ma, Guiping

    2017-09-01

    One-dimensional (1D) nanomaterials have gained attention in energy conversion, storage, and catalyst due to the unique physical and chemical properties. Electrospinning is a kind of simple, versatile, and cost-effective technology to fabricate 1D functional nanofibers. Herein, electrospun polyacrylonitrile (PAN), melamine, and ferric chloride hexahydrate (FeCl3·6H2O) composite nanofibers are used as template, and polythiophene (PT) are prepared by photopolymerization technology on the surface of electrospun nanofibers as shell part of fibers. Then, the core-shell nanofibers are pyrolyzed and converted into Fe-S/N-C nanofibers, which can be used as catalysts for ORR due to the metal and S-/N-codoped structure and unique 1D structure which provided facile pathways for efficient mass transport and charge transfer. The ORR electrocatalytic ability of Fe-S/N-C nanofibers is tested and present excellent property, especially in stability and methanol crossover. The electrocatalytic ability of sample is comparable to that of 20 wt% Pt/C benchmarks. These results offer an easy pathway for exploring metal-heteroatom-codoped carbon nanofibers applicable for ORR catalyst.

  3. Synthesis of Core-Shell Si O /Carbon Nanofibers on Silicon Substrates by Ultrasonic Spray Pyrolysis

    OpenAIRE

    Zhang, Jianhui; Kishi, Naoki; Soga, Tetsuo; Jimbo, Takashi; Tanji, Takayoshi

    2012-01-01

    We synthesized the core-shell Si O /carbon nanofibers with diameters of 200–300 nm using ultrasonic spray pyrolysis with a phosphorus/ethanol mixture. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive spectroscopy (EDS) investigations confirmed the core-shell structure, which consisted of a core of Si O and a shell of amorphous carbon. The phosphorus atoms corroded the entire silicon substrate surface, and the Si-P liquid-catalyzed the solid-liquid-solid mecha...

  4. Fabrication of Carbon Nanofibers/A356 Nanocomposites by High-Intensity Ultrasonic Processing

    Science.gov (United States)

    Wu, Qing-Jie; Yan, Hong

    2018-03-01

    A356 alloy reinforced with carbon nanofibers (CNFs) was fabricated by high-intensity ultrasonic vibration processing. The microstructure and mechanical properties were investigated. The distribution of CNFs became more and more uniform with the increase of ultrasonic power, and the mechanical properties of nanocomposites were significantly enhanced accordingly. The yield strength (YS), ultimate tensile strength (UTS), and microhardness of the nanocomposite increased by 38.3, 21.9, and 43.2 pct, respectively, at a CNF content of 0.9 wt pct compared with the matrix without CNF addition. The improvement in mechanical properties was the effect of CNFs on the thermal expansion mismatch strengthening of the nanocomposite, the grain refinement of the nanocomposite, and the load transfer from the matrix to the nanofibers.

  5. 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.

  6. Nanoscratch technique for aligning multiwalled carbon nanotubes ...

    Indian Academy of Sciences (India)

    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 ...

  7. Synthesis of Core-Shell SiO/Carbon Nanofibers on Silicon Substrates by Ultrasonic Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Jianhui Zhang

    2012-01-01

    Full Text Available We synthesized the core-shell SiO/carbon nanofibers with diameters of 200–300 nm using ultrasonic spray pyrolysis with a phosphorus/ethanol mixture. High-resolution transmission electron microscopy (HRTEM and energy-dispersive spectroscopy (EDS investigations confirmed the core-shell structure, which consisted of a core of SiO and a shell of amorphous carbon. The phosphorus atoms corroded the entire silicon substrate surface, and the Si-P liquid-catalyzed the solid-liquid-solid mechanism is proposed to explain the growth of the core-shell SiO/carbon nanofibers.

  8. Flexible binder-free silicon/silica/carbon nanofiber composites as anode for lithium–ion batteries

    International Nuclear Information System (INIS)

    Dirican, Mahmut; Yildiz, Ozkan; Lu, Yao; Fang, Xiaomeng; Jiang, Han; Kizil, Huseyin; Zhang, Xiangwu

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: • Flexible Si/SiO 2 /C composite nanofibers were introduced as Li–ion battery anodes. • SiO 2 component of composite nanofibers facilitated the high flexibility. • Flexible Si/SiO 2 /C composite nanofibers were coated with CVD-carbon. • CVD carbon coating and SiO 2 component led to high capacity retention. -- Abstract: High-capacity flexible electrode materials for high-energy lithium–ion batteries become critically important with technological improvements on portable and bendable electronic equipment such as rollup displays, implantable medical devices, active radio-frequency identification tags, and wearable devices. Although different types of bendable electrode materials have been introduced, it is very important to fabricate highly-flexible electrode materials with reasonable fabrication technique and high electrochemical performance similar to those of conventional high-capacity electrode materials. Herein, we introduced high-capacity, flexible Si/SiO 2 /C nanofiber composite anode materials by simple electrospinning and subsequent heat treatment processes. To further improve the long-term cycling performance, additional nanoscale carbon coating of flexible Si/SiO 2 /C nanofibers was performed by CVD technique. Electrochemical performance results showed that CVD carbon-coated flexible Si/SiO 2 /C nanofiber composites exhibited high capacity retention of 86.7% and high coulombic efficiency of 96.7% at the 50th cycle. It is, therefore, demonstrated that CVD carbon-coated flexible Si/SiO 2 /C nanofiber composites are promising anode material candidate for next-generation flexible and high-energy lithium–ion batteries

  9. Carbon nanofiber vs. carbon microparticles as modifiers of glassy carbon and gold electrodes applied in electrochemical sensing of NADH.

    Science.gov (United States)

    Pérez, Briza; Del Valle, Manel; Alegret, Salvador; Merkoçi, Arben

    2007-12-15

    Carbon materials (CMs), such as carbon nanotubes (CNTs), carbon nanofibers (CNFs), and carbon microparticles (CMPs) are used as doping materials for electrochemical sensors. The efficiency of these materials (either before or after acidic treatments) while being used as electrocatalysts in electrochemical sensors is discussed for beta-nicotinamide adenine dinucleotide (NADH) detection using cyclic voltammetry (CV). The sensitivity of the electrodes (glassy carbon (GC) and gold (Au)) modified with both treated and untreated materials have been deeply studied. The response efficiencies of the GC and Au electrodes modified with CNF and CMP, using dimethylformamide (DMF) as dispersing agent are significantly different due to the peculiar physical and chemical characteristics of each doping material. Several differences between the electrocatalytic activities of CMs modified electrodes upon NADH oxidation have been observed. The CNF film promotes better the electron transfer of NADH minimizing the oxidation potential at +0.352 V. Moreover higher currents for the NADH oxidation peak have been observed for these electrodes. The shown differences in the electrochemical reactivities of CNF and CMP modified electrodes should be with interest for future applications in biosensors.

  10. Synthesis of copper particles covered with cobalt-catalyzed carbon nanofibers and their application to air-curable conductive paste

    Science.gov (United States)

    Ohnishi, Shigekatsu; Nakasuga, Akira; Nakagawa, Kiyoharu

    2017-07-01

    Sea urchin-shaped hybrid copper powder (HCuP), which is characterized by copper alloy powder particles covered with vertically aligned Co-catalyzed carbon nanofibers (CNFs), was successfully synthesized to improve the oxidation resistance of copper paste. Fine spherical CuCo alloy particles with nominal composition of Cu/Co = 99/1 w/w were fabricated by atomization. Cobalt nanoprecipitates (CoNPs) used as the catalyst for carbon fiber growth were arranged on the surface of an alloy particle by heat treatment. CNFs were grown from the CoNPs on the alloy particle via thermal chemical vapor deposition (CVD). The conductive paste was prepared by milling using HCuP with resin and oleic acid. HCuP paste was screen-printed on a glass or plastic substrate and showed a resistivity as low as 1.2 × 10-4 Ω·cm after curing at 150 °C for 30 min in air (21% oxygen). These results indicate that the use of HCuP is a promising technology for printable electronics in a sustainable society.

  11. Morphology and Structure Engineering in Nanofiber Reactor: Tubular Hierarchical Integrated Networks Composed of Dual Phase Octahedral CoMn2 O4 /Carbon Nanofibers for Water Oxidation.

    Science.gov (United States)

    Zhu, Han; Yu, Danni; Zhang, Songge; Chen, Jiawei; Wu, Wenbo; Wan, Meng; Wang, Lina; Zhang, Ming; Du, Mingliang

    2017-07-01

    1D hollow nanostructures combine the advantages of enhanced surface-to-volume ratio, short transport lengths, and efficient 1D electron transport, which can provide more design ideas for the preparation of highly active oxygen evolution (OER) electrocatalysts. A unique architecture of dual-phase octahedral CoMn 2 O 4 /carbon hollow nanofibers has been prepared via a two-step heat-treatment process including preoxidation treatment and Ostwald ripening process. The hollow and porous structures provide interior void spaces, large exposed surfaces, and high contact areas between the nanofibers and electrolyte and the morphology can be engineered by adjusting the heating conditions. Due to the intimate electrical and chemical coupling between the oxide nanocrystals and integrated carbon, the dual-phase octahedral CoMn 2 O 4 /carbon hollow nanofibers exhibit excellent OER activity with overpotentials of 337 mV at current density of 10 mA cm -2 and Tafel slope of 82 mV dec -1 . This approach will lead to the new perception of design issue for the nanoarchitecture with fine morphology, structures, and excellent electrocatalytic activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Synthesis and photocatalytic properties of graphitic carbon nitride nanofibers using porous anodic alumina templates

    Science.gov (United States)

    Suchitra, S. M.; Udayashankar, N. K.

    2017-12-01

    In the present study, we describe an effective method for the synthesis of Graphitic carbon nitride (GCN) nanostructures using porous anodic alumina (AAO) membrane as template by simple thermal condensation of cyanamide. Synthesized nanostructure was fully analysed by various techniques to detect its crystalline nature, morphology, luminescent properties followed by the evaluation of its photocatalytic activity in the degradation of Methylene blue dye. Structural analysis of synthesized GCNNF was systematically carried out using x-ray powder diffraction (XRD) and scanning electron microscope (SEM), and. The results confirmed the growth of GCN inside the nanochannels of anodic alumina templates. Luminescent properties of GCNNF were studied using photoluminescence (PL) spectroscopy. PL analysis showed the presence of a strong emission peak in the wavelength range of 350–600 nm in blue region. GCNNF displays higher photocatalytic performance in the photodegradation of methylene blue compare to the bulk GCN. Highlights 1. In the present paper, we report the synthesis of graphitic carbon nitride nanofibers (GCNNF) using porous anodic aluminium oxide membranes as templates through thermal condensation of cyanamide at 500 °C. 2. The synthesis of Graphitic carbon nitride nanofibers using porous andic alumina template is the efficient approach for increasing crystallinity and surface area. 3. The high surface area of graphitic carbon nitride nanofibers has a good impact on novel optical and photocatalytic properties of the bulkGCN. 4. AAO templating of GCN is one of the versatile method to produce tailorable GCN nanostructures with higher surface area and less number of structural defects. 5. Towards photocatalytic degradation of dyes, the tuning of physical properties is very essential thing hence we are succeeded in achieving better catalytic performance of GCN nanostructures by making use of AAO templates.

  13. Electrical Removal Behavior of Carbon Nanotube and Carbon Nanofiber Film in CuCl2 Solution: Kinetics and Thermodynamics Study

    Directory of Open Access Journals (Sweden)

    Yankun Zhan

    2011-01-01

    Full Text Available The kinetics, thermodynamics, and isotherms during electrical removal of Cu2+ by carbon nanotube and carbon nanofiber (CNT-CNF electrodes in CuCl2 solution were studied under different solution temperatures, initial Cu2+ concentrations, and applied voltages. The result shows that Langmuir isotherm can describe experimental data well, indicating monolayer adsorption, and higher Cu2+ removal and rate constant are achieved at higher voltage, lower initial Cu2+ concentration, and higher solution temperature. Meanwhile, the thermodynamics analyses indicate that the electrical removal of Cu2+ onto CNT-CNF electrodes is mainly driven by a physisorption process.

  14. Fabrication of a Mechanically Robust Carbon Nanofiber Foam

    Science.gov (United States)

    2015-06-01

    7] D. Futaba et al., “Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super - capacitor ...and highly densely packed single-walled carbon nanotubes and their application as super - capacitor electrodes,” Nat. Mater, vol. 5, pp. 987–994, Dec

  15. Electrostatic Adsorption of Platinum onto Carbon Nanotubes and Nanofibers for Nanoparticle Synthesis

    Directory of Open Access Journals (Sweden)

    Ritubarna Banerjee

    2018-02-01

    Full Text Available Strong Electrostatic Adsorption (SEA has been demonstrated as a simple, scientific method to prepare well dispersed Pt nanoparticles over typical forms of carbon: activated, black, and graphitic carbons. Many varieties of specialty carbons have been invented in the last few decades including multi-walled nanotubes, nanofibers, graphene nanoplatelets, etc. In this work, we explore whether SEA can be applied to these specialty carbons for the synthesis of Pt nanoparticles. Over a number of oxidized and unoxidized multiwalled nanotubes and nanofibers, the point of zero charge (PZC was measured and the uptake of anionic Pt complexes (Pt hexachloride, [PtCl6]2−, and cationic Pt complexes (platinum tetraammine, [Pt(NH34]2+ as functions of final pH were surveyed. Pt nanoparticles on the various supports were synthesized at the optimal pH and were characterized by x-ray diffraction (XRD and scanning transmission electron microscopy (STEM. The specialty carbons displayed volcano-shaped uptake curves typical of electrostatic adsorption for both Pt anions at low pH and Pt cations at high pH. However, the regimes of uptake often did not correspond to the measured PZC, probably due to surface impurities from the carbon manufacturing process. This renders the measured PZC of these specialty carbons unreliable for predicting anion and cation uptake. On the other hand, the anion and cation uptake curves provide an “effective” PZC and do indicate the optimal pH for the synthesis of ultrasmall nanoparticle synthesis. High resolution STEM imaging also showed that with SEA it is possible to disperse nanoparticles on the surface as well as the inner walls of the specialty carbons.

  16. The effect of filler aspect ratio on the electromagnetic properties of carbon-nanofibers reinforced composites

    Energy Technology Data Exchange (ETDEWEB)

    De Vivo, B.; Lamberti, P.; Spinelli, G., E-mail: gspinelli@unisa.it; Tucci, V. [Department of Information Engineering, Electrical Engineering and Applied Mathematics—DIEM, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano SA (Italy); Guadagno, L.; Raimondo, M. [Department of Industrial Engineering—DIIn, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano SA (Italy)

    2015-08-14

    The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500 °C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107 S/m and 1.36 × 10{sup −3} S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1 wt. % of nanofiller loading, while the electrical percolation threshold falls in the range [0.05–0.32]wt. % for the first nanocomposites and above 0.64 wt. % for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.

  17. High-Throughput Image Analysis of Fibrillar Materials: A Case Study on Polymer Nanofiber Packing, Alignment, and Defects in Organic Field Effect Transistors.

    Science.gov (United States)

    Persson, Nils E; Rafshoon, Joshua; Naghshpour, Kaylie; Fast, Tony; Chu, Ping-Hsun; McBride, Michael; Risteen, Bailey; Grover, Martha; Reichmanis, Elsa

    2017-10-18

    High-throughput discovery of process-structure-property relationships in materials through an informatics-enabled empirical approach is an increasingly utilized technique in materials research due to the rapidly expanding availability of data. Here, process-structure-property relationships are extracted for the nucleation, growth, and deposition of semiconducting poly(3-hexylthiophene) (P3HT) nanofibers used in organic field effect transistors, via high-throughput image analysis. This study is performed using an automated image analysis pipeline combining existing open-source software and new algorithms, enabling the rapid evaluation of structural metrics for images of fibrillar materials, including local orientational order, fiber length density, and fiber length distributions. We observe that microfluidic processing leads to fibers that pack with unusually high density, while sonication yields fibers that pack sparsely with low alignment. This is attributed to differences in their crystallization mechanisms. P3HT nanofiber packing during thin film deposition exhibits behavior suggesting that fibers are confined to packing in two-dimensional layers. We find that fiber alignment, a feature correlated with charge carrier mobility, is driven by increasing fiber length, and that shorter fibers tend to segregate to the buried dielectric interface during deposition, creating potentially performance-limiting defects in alignment. Another barrier to perfect alignment is the curvature of P3HT fibers; we propose a mechanistic simulation of fiber growth that reconciles both this curvature and the log-normal distribution of fiber lengths inherent to the fiber populations under consideration.

  18. 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.

  19. Synthesis of a novel carbon nanofiber structure for removal of lead

    Energy Technology Data Exchange (ETDEWEB)

    Faghihian, Hossein; Kooravand, Masoume; Atarodi, Homa [Islamic Azad University, Shahreza (Iran, Islamic Republic of)

    2013-02-15

    A new structure of carbon nanofibers was synthesized by chemical vapor deposition method. Kaolin was used as substrate and cyclohexanol and ferrocene as carbon source and catalyst, respectively. The morphology of the product was studied by scanning electron microscopy. Carbon nanofiber was modified with a mixture of nitric acid and sulfuric acid to enhance its adsorption capacity. The presence of functional groups on the treated adsorbent was assessed by FT-IR spectroscopy. The surface activity of the oxidized sample was estimated by Boehm’s titration. The pH{sub (PZC)} of the samples was also measured. The adsorbent was then used for adsorption of Pb{sup 2+} at different experimental conditions. The optimized capacity of 211mg·g{sup −1} was obtained. Kinetic and thermodynamic of the reaction were studied. It was concluded that the adsorption process is spontaneous and endothermic. Equilibrium data were well fitted to the Langmuir model and the pseudo-second-order kinetic model described the adsorption process.

  20. Facile synthesis of NiS anchored carbon nanofibers for high-performance supercapacitors

    Science.gov (United States)

    Xu, Jinling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhang, Chi; Ma, Xin; Qi, Chunling; Zhang, Lu; Jia, Dianzeng

    2018-03-01

    Transition metal sulfide compounds with carbon materials are promising for high-performance supercapacitors. Carbon nanofibers (CNFs) wrapped with NiS nanoparticles were herein obtained through electrospinning and calcination. NiS nanoparticles in composite nanofibers are covered by a layer of graphitic carbon, which not only increase the conductivity but also provide active regions for nanoparticle growth to prevent aggregation. The CNFs-NiS electrode has high specific capacity of 177.1 mAh g-1 at 1 A g-1 (0.41 mAh cm-2 at a current density of 2.3 mA cm-2) and long-term cycling stability, with 88.7% capacitance retention after 5000 cycles. The excellent electrochemical activity may be attributed to the accessible specific surface, unique porous structure of CNFs and high specific capacitance of NiS. In addition, the asymmetric supercapacitor has an enhanced volumetric energy density of 13.32 mWh cm-3 at a volumetric power density of 180 mW cm-3 and high cycling stability, with 89.5% capacitance retention after 5000 cycles. It also successfully lights up a light-emitting diode. The CNFs-NiS composite has significant potential applications in supercapacitor.

  1. Synthesis of a novel carbon nanofiber structure for removal of lead

    International Nuclear Information System (INIS)

    Faghihian, Hossein; Kooravand, Masoume; Atarodi, Homa

    2013-01-01

    A new structure of carbon nanofibers was synthesized by chemical vapor deposition method. Kaolin was used as substrate and cyclohexanol and ferrocene as carbon source and catalyst, respectively. The morphology of the product was studied by scanning electron microscopy. Carbon nanofiber was modified with a mixture of nitric acid and sulfuric acid to enhance its adsorption capacity. The presence of functional groups on the treated adsorbent was assessed by FT-IR spectroscopy. The surface activity of the oxidized sample was estimated by Boehm’s titration. The pH (PZC) of the samples was also measured. The adsorbent was then used for adsorption of Pb 2+ at different experimental conditions. The optimized capacity of 211mg·g −1 was obtained. Kinetic and thermodynamic of the reaction were studied. It was concluded that the adsorption process is spontaneous and endothermic. Equilibrium data were well fitted to the Langmuir model and the pseudo-second-order kinetic model described the adsorption process

  2. DIRECT GROWTH OF VERTICALLY ALIGNED CARBON ...

    African Journals Online (AJOL)

    characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray ... Silicon substrates of dimension of 1 cm x 1 ..... A Gen. 2010, 384, 27-35. 21. He. D.L.; Li. H.; Li. W.; Haghi-Ashitani. P.; Lejay. P.; Bai. J. Growth of carbon nanotubes in six orthogonal directions on spherical alumina ...

  3. 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.

  4. Thermoplastic polybutadiene-based polyurethane/carbon nanofiber composites

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Duszová, A.; Poreba, Rafal; Kredatusová, Jana; Bureš, R.; Fáberová, M.; Šlouf, Miroslav

    2014-01-01

    Roč. 67, December (2014), s. 434-440 ISSN 1359-8368 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : carbon fibre * polymer–matrix composites (PMCs) * mechanical properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.983, year: 2014

  5. Design and evaluation of carbon nanofiber and silicon materials for neural implant applications

    Science.gov (United States)

    McKenzie, Janice L.

    Reduction of glial scar tissue around central nervous system implants is necessary for improved efficacy in chronic applications. Design of materials that possess tunable properties inspired by native biological tissue and elucidation of pertinent cellular interactions with these materials was the motivation for this study. Since nanoscale carbon fibers possess the fundamental dimensional similarities to biological tissue and have attractive material properties needed for neural biomaterial implants, this present study explored cytocompatibility of these materials as well as modifications to traditionally used silicon. On silicon materials, results indicated that nanoscale surface features reduced astrocyte functions, and could be used to guide neurite extension from PC12 cells. Similarly, it was determined that astrocyte functions (key cells in glial scar tissue formation) were reduced on smaller diameter carbon fibers (125 nm or less) while PC12 neurite extension was enhanced on smaller diameter carbon fibers (100 nm or less). Further studies implicated laminin adsorption as a key mechanism in enhancing astrocyte adhesion to larger diameter fibers and at the same time encouraging neurite extension on smaller diameter fibers. Polycarbonate urethane (PCU) was then used as a matrix material for the smaller diameter carbon fibers (100 and 60 nm). These composites proved very versatile since electrical and mechanical properties as well as cell functions and directionality could be influenced by changing bulk and surface composition and features of these matrices. When these composites were modified to be smooth at the micronscale and only rough at the nanoscale, P19 cells actually submerged philopodia, extensions, or whole cells bodies beneath the PCU in order to interact with the carbon nanofibers. These carbon nanofiber composites that have been formulated are a promising material to coat neural probes and thereby enhance functionality at the tissue interface. This

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

    Science.gov (United States)

    Calderón, Juan Carlos; Rios Ráfales, Miguel; Nieto-Monge, María Jesús; Pardo, Juan Ignacio; Moliner, Rafael; Lázaro, María Jesús

    2016-01-01

    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. PMID:28335315

  7. 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.

  8. Use of Carbon Nano-Fiber Foams as Strain Gauges to Detect Crack Propagation

    Science.gov (United States)

    2015-06-01

    capacitors [18]. Another example are recent attempts to use carbon fibers and carbon nanotubes to develop sensor devices. Sida Luo created aligned...ring caps made out of Ethlyene-Propylene • Super Glue (Cyanoacrylate, C5H5NO2) • One sheet of aluminum foil • AL5083 specimen (27.94 mm Length, 2.54

  9. Radiation grafting of methacrylate onto carbon nanofiber surface

    International Nuclear Information System (INIS)

    Evora, M.C.; Klosterman, D.; Lafdi, K.; Li, L.

    2011-01-01

    Radiation can be used to modify and improve the properties of materials. Electron beam irradiation has potential application in modifying the structure of carbon fibers in order to produce useful defects in the graphite structure and create reactive sites. In this study, vapor grown carbon nano fibers (VGCF) were irradiated with a high energy (3 MeV) electron beam in air to dose of 1000 kGy to create active sites and added to methyl methacrylate (MMA) dissolved in water/methanol (50% V). The irradiated samples were analyzed by X-Ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy to assess the impact on surface and bulk properties. Oxygen was readily incorporated enhancing the dispersion of VGCF. Raman spectroscopy analyses indicated that the sample irradiated and preirradiated grafted sample with MMA had the intensity ratio increased. (author)

  10. Supercapacitor Electrode Materials from Highly Porous Carbon Nanofibers with Tailored Pore Distributions

    Science.gov (United States)

    Chathurika Abeykoon, Nimali

    Environmental and human health risks associated with the traditional methods of energy production (e.g., oil and gas) and intermittency and uncertainty of renewable sources (e.g., solar and wind) have led to exploring effective and alternative energy sources to meet the growing energy demands. Electricity based on energy storage devices are the most promising solutions for realization of these objectives. Among the energy storage devices, electrochemical double layer capacitors (EDLCs) or supercapacitors have become an attractive research interest due to their outstanding performance, especially high power densities, long cycle life and rapid charge and discharge times, which enables them to utilize in many applications including consumer electronics and transportation, where high power is needed. However, low energy density of supercapacitors is a major obstacle to compete with the commercially existing high energy density energy storage device such as batteries. The fabrication of advanced electrodes materials with very high surface area from novel precursors and utilization of electrolytes with higher operating voltages are essential to enhance energy density of supercapacitors. In this work, carbon nanofibers (CNFs) from different polymer precursors with new fabrication techniques are explored to develop highly porous carbon with tailored pore distributions to match with employed ionic liquid electrolytes (which possess high working voltages), to realize high energy storage capability. Novel electrode materials derived from electrospun immiscible polymer blends and synthesized copolymers and terpolymers were described. Pore distributions of CNFs were tailored by varying the composition of polymers in immiscible blends or varying the monomer ratios of copolymer or terpolymers. Chapter 1 gives the detailed introduction of supercapacitors including history and storage principle of EDLCs, fabrication of carbon nanofiber based electrodes and electrolytes employed

  11. Fabrication of ultrafine manganese oxide-decorated carbon nanofibers for high-performance electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Lee, Sungsik; Brown, Dennis E.; Zhao, Hairui; Li, Xinsong; Jiang, Daqiang; Hao, Shijie; Zhao, Yongxiang; Cong, Daoyong; Zhang, Xin; Ren, Yang

    2016-09-01

    Ultrafine manganese oxide-decorated carbon nanofibers (MnOn-CNF) as a new type of electrode materials are facilely fabricated by direct conversion of Mn, Zn-trimesic acid (H3BTC) metal organic framework fibers (Mn-ZnBTC). The construction and evolution of Mn-ZnBTC precursors are investigated by SEM and in situ high-energy XRD. The manganese oxides are highly dispersed onto the porous carbon nanofibers formed simultaneously, verified by TEM, X-ray absorption fine structure (XAFS), Raman, ICP-AES and N2 adsorption techniques. As expected, the resulting MnOn-CNF composites are highly stable, and can be cycled up to 5000 times with a high capacitance retention ratio of 98% in electrochemical capacitor measurements. They show a high capacitance of up to 179 F g–1 per mass of the composite electrode, and a remarkable capacitance of up to 18290 F g–1 per active mass of the manganese(IV) oxide, significantly exceeding the theoretical specific capacitance of manganese(IV) oxide (1370 F g–1). The maximum energy density is up to 19.7 Wh kg–1 at the current density of 0.25 A g–1, even orders higher than those of reported electric double-layer capacitors and pseudocapacitors. The excellent capacitive performance can be ascribed to the joint effect of easy accessibility, high porosity, tight contact and superior conductivity integrated in final MnOn-CNF composites.

  12. Chloride-Reinforced Carbon Nanofiber Host as Effective Polysulfide Traps in Lithium-Sulfur Batteries.

    Science.gov (United States)

    Fan, Lei; Zhuang, Houlong L; Zhang, Kaihang; Cooper, Valentino R; Li, Qi; Lu, Yingying

    2016-12-01

    Lithium-sulfur (Li-S) battery is one of the most promising alternatives for the current state-of-the-art lithium-ion batteries due to its high theoretical energy density and low production cost from the use of sulfur. However, the commercialization of Li-S batteries has been so far limited to the cyclability and the retention of active sulfur materials. Using co-electrospinning and physical vapor deposition procedures, we created a class of chloride-carbon nanofiber composites, and studied their effectiveness on polysulfides sequestration. By trapping sulfur reduction products in the modified cathode through both chemical and physical confinements, these chloride-coated cathodes are shown to remarkably suppress the polysulfide dissolution and shuttling between lithium and sulfur electrodes. From adsorption experiments and theoretical calculations, it is shown that not only the sulfide-adsorption effect but also the diffusivity in the vicinity of these chlorides materials plays an important role on the reversibility of sulfur-based cathode upon repeated cycles. Balancing the adsorption and diffusion effects of these nonconductive materials could lead to the enhanced cycling performance of an Li-S cell. Electrochemical analyses over hundreds of cycles indicate that cells containing indium chloride-modified carbon nanofiber outperform cells with other halogenated salts, delivering an average specific capacity of above 1200 mAh g -1 at 0.2 C.

  13. Electrically conductive carbon nanofiber/paraffin wax composites for electric thermal storage

    International Nuclear Information System (INIS)

    Zhang Kun; Han Baoguo; Yu Xun

    2012-01-01

    Highlights: ► Carbon nanofiber (CNF)/paraffin wax composite is found to be a promising electric thermal storage material. ► The thermal storage capacity of CNF/paraffin wax composite is five times of traditional electric thermal storage material. ► CNF is shown to be an effective conductive filler for the composite. - Abstract: The research of electric thermal storage (ETS) has attracted a lot of attention recently, which converts off-peak electrical energy into thermal energy and release it later at peak hours. In this study, new electric thermal storage composites are developed by employing paraffin wax as thermal storage media and carbon nanofiber (CNF) as conductive fillers. Electric heating and thermal energy release performances of the CNF/paraffin wax composites are experimentally investigated. Experimental results show that, when the composites are heated to about 70 °C, the developed electrically conductive CNF/paraffin wax composites present a thermal storage capacity of about 280 kJ/kg, which is five times of that of traditional thermal storage medium such as ceramic bricks (54 kJ/kg). The CNF/paraffin wax composites can also effectively store the thermal energy and release the thermal energy in later hours.

  14. 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.

  15. The study of hydrogen electrosorption in layered nickel foam/palladium/carbon nanofibers composite electrodes

    International Nuclear Information System (INIS)

    Skowronski, J.M.; Czerwinski, A.; Rozmanowski, T.; Rogulski, Z.; Krawczyk, P.

    2007-01-01

    In the present work, the process of hydrogen electrosorption occurring in alkaline KOH solution on the nickel foam/palladium/carbon nanofibers (Ni/Pd/CNF) composite electrodes is examined. The layered Ni/Pd/CNF electrodes were prepared by a two-step method consisting of chemical deposition of a thin layer of palladium on the nickel foam support to form Ni/Pd electrode followed by coating the palladium layer with carbon nanofibers layer by means of the CVD method. The scanning electron microscope was used for studying the morphology of both the palladium and carbon layer. The process of hydrogen sorption/desorption into/from Ni/Pd as well as Ni/Pd/CNF electrode was examined using the cyclic voltammetry method. The amount of hydrogen stored in both types of composite electrodes was shown to increase on lowering the potential of hydrogen sorption. The mechanism of the anodic desorption of hydrogen changes depending on whether or not CNF layer is present on the Pd surface. The anodic peak corresponding to the removal of hydrogen from palladium is lower for Ni/Pd/CNF electrode as compared to that measured for Ni/Pd one due to a partial screening of the Pd surface area by CNF layer. The important feature of Ni/Pd/CNF electrode is anodic peak appearing on voltammetric curves at potential ca. 0.4 V more positive than the peak corresponding to hydrogen desorption from palladium. The obtained results showed that upon storing the hydrogen saturated Ni/Pd/CNF electrode at open circuit potential, diffusion of hydrogen from carbon to palladium phase occurs due to interaction between carbon fibers and Pd sites on the nickel foam support

  16. Electrospun carbon nanotube composite nanofibres with uniaxially aligned arrays

    International Nuclear Information System (INIS)

    Zhang Qinghua; Chang Zhenjun; Zhu Meifang; Mo Xiumei; Chen Dajun

    2007-01-01

    Multiwalled carbon nanotubes (MWNTs) were functionalized by grafting Triton X-100 on their surface to improve their dispersion in a solution of polyacrylonitrile (PAN) matrix. Well-aligned composite nanofibres containing PAN and MWNTs were prepared by electrospinning in dimethyl formamide solution, and a collector consisting of two pieces of electrode was used to catch the nanofibres, as well as a slowly rotating drum with multi-electrodes. The nanofibres, with diameters of ∼100 nm, can be uniaxially aligned across the gap between the parallel electrodes. TEM images showed that the individual surface-functionalized MWNTs were embedded within the nanofibres

  17. Particle size effects for carbon nanofiber supported platinum and ruthenium catalysts for the selective hydrogenation of cinnamaldehyde

    NARCIS (Netherlands)

    Plomp, A.J.; Vuori, H.; Krause, A.O.I.; de Jong, K.P.; Bitter, J.H.

    2008-01-01

    The selective hydrogenation of cinnamaldehyde was studied over carbon nanofibers (CNF) supported platinum and ruthenium catalysts. The catalysts differed independently in their metal particle sizes and amount of acidic oxygen groups on the CNF surface. For the catalysts with oxygen on the CNF

  18. Gas phase oxidation as a tool to introduce oxygen containing groups on metal-loaded carbon nanofibers

    NARCIS (Netherlands)

    Gosselink, R.W.|info:eu-repo/dai/nl/326164081; van den Berg, R.; Xia, B.; Muhler, M.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X; Bitter, J.H.|info:eu-repo/dai/nl/160581435

    2012-01-01

    Oxygen containing groups were introduced, onto carbon nanofibers (CNFs) that were previously loaded with palladium, using HNO3 vapor. Using traditional liquid-phase oxidations this is not possible due to severe metal leaching. For the samples oxidized using HNO3 vapor temperature programmed

  19. 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.

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

    NARCIS (Netherlands)

    Jarah nabeel abdul kareem amin, N.A.K.A.; Jarrah, Nabeel A.; van Ommen, J.G.; Lefferts, Leonardus

    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

  1. A smart strategy to fabricate Ru nanoparticle inserted porous carbon nanofibers as highly efficient levulinic acid hydrogenation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Sun, Cheng-Jun; Brown, Dennis E.; Zhang, Liqiang; Yang, Feng; Zhao, Hairui; Wang, Yue; Ma, Xiaohui; Zhang, Xin; Ren, Yang

    2016-01-01

    Herein, we first put forward a smart strategy to in situ fabricate Ru nanoparticle (NP) inserted porous carbon nanofibers by one-pot conversion of Ru-functionalized metal organic framework fibers. Such fiber precursors are skillfully constructed by cooperative assembly of different proportional RuCl3 and Zn(Ac)2·2H2O along with trimesic acid (H3BTC) in the presence of N,N-dimethylformamide. The following high-temperature pyrolysis affords uniform and evenly dispersed Ru NPs (ca. 12-16 nm), which are firmly inserted into the hierarchically porous carbon nanofibers formed simultaneously. The resulting Ru-carbon nanofiber (Ru-CNF) catalysts prove to be active towards the liquid-phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), a biomass-derived platform molecule with wide applications in the preparation of renewable chemicals and liquid transportation fuels. The optimal GVL yield of 96.0% is obtained, corresponding to a high activity of 9.23 molLAh–1gRu–1, 17 times of that using the commercial Ru/C catalyst. Moreover, the Ru-CNF catalyst is extremely stable, and can be cycled up to 7 times without significant loss of reactivity. Our strategy demonstrated here reveals new possibilities to make proficient metal catalysts, and provides a general way to fabricate metal-carbon nanofiber composites available for other applications.

  2. Spectroscopic study of nitrogen distribution in N-doped carbon nanotubes and nanofibers synthesized by catalytic ethylene-ammonia decomposition

    Science.gov (United States)

    Svintsitskiy, Dmitry A.; Kibis, Lidiya S.; Smirnov, Dmitry A.; Suboch, Arina N.; Stonkus, Olga A.; Podyacheva, Olga Yu.; Boronin, Andrei I.; Ismagilov, Zinfer R.

    2018-03-01

    Carbon and nitrogen species on the surface of carbon nanotubes (N-CNTs) and nanofibers (N-CNFs) were studied by X-ray absorption (XAS) and photoelectron spectroscopy (PES) including the analysis of nitrogen distribution over the depth of materials. The study was performed with a series of bamboo-like carbon nanotubes and nanofibers having the platelet-like and herringbone-like morphology. It was shown that the main nitrogen species in the composition of the studied materials are pyridine, pyrrole (and/or amino groups), graphite-like and oxidized states of nitrogen. In distinction to nanofibers, the bamboo-like nanotubes additionally contain molecular nitrogen encapsulated in the internal hollows. Spectral data for different depths of analysis were obtained by varying the energy of incident radiation. Such an approach revealed that N-CNTs are characterized by non-uniform distribution of chemically bound nitrogen species. Thus, nitrogen enrichment was observed on the external surface and in the internal arches of carbon nanotubes. Nitrogen enrichment in the subsurface region was found for N-CNFs, whereas the full depth analysis of N-distribution was limited by a large diameter of nanofibers.

  3. 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.

  4. Synthesis of Polyaniline (PANI in Nano-Reaction Field of Cellulose Nanofiber (CNF, and Carbonization

    Directory of Open Access Journals (Sweden)

    Yuki Kaitsuka

    2016-02-01

    Full Text Available Polymerization of aniline in the presence of cellulose nano-fiber (CNF is carried out. We used dried CNF, CNF suspension, and CNF treated by enzyme and ultra-sonification to obtain polyaniline (PANI/CNF as a synthetic polymer/natural nano-polymer composite. The polymerization proceeds on the surface of CNF as a nano-reaction field. Resultant composites show extended effective π-conjugation length because CNF as a reaction field in molecular level produced polymer with expanded coil structure with an aid of orientation effect of CNF. Possibility of PANI β-pleats structure in molecular level of PANI on the CNF is also discussed. SEM observation showed that fine structure is easily obtained by combining PANI with CNF. Carbonization of PANI/CNF allows production of nano-fine form with shape preserved carbonization (SPC.

  5. Microstructure and electrochemical properties of polyacrylonitrile-based carbon micro- and nanofibers fabricated by centrifugal spinning

    Science.gov (United States)

    Zhao, Hang; Min, Xin; Wu, Xiaowen; Wang, Huan; Liu, Jia; Zhang, Zhijie; Huang, Zhaohui; Liu, Yan-gai; Fang, Minghao

    2017-09-01

    Carbon nanofibers were prepared by using centrifugal spinning with polyacrylonitrile as precursor. The microstructure and electrochemical properties of prepared samples were investigated by using scanning electron microscopy and electrochemical workstation, respectively. The results showed that the distribution of fiber diameter showed a normal law. The carbon fibers present good cycle stability at low scan rate. Moreover, the integral area of cyclic voltammetry curve reaches the maximum when the mass ratio of PAN/PMMA is 20:3. The specific capacitance of it is 102 F/g and 84 F/g, in case of the current density at 0.1 A/g and 0.2 A/g, respectively.

  6. Hydrogen Adsorption in Flame Synthesized and Lithium Intercalated Carbon Nanofibers--A Comparative Study.

    Science.gov (United States)

    Dhand, Vivek; Prasad, J Sarada; Rao, Venkateswer M; Kalluri, Sujith; Jain, Pawan Kumar; Sreedhar, B

    2015-01-01

    Carbon nanofibers (CNF) have been synthesized under partial combustion conditions in a flame reactor using different mixtures of hydrocarbon gases in the presence and absence of precursors. The hydrogen (H2) adsorption studies have been carried out using a high pressure Sievert's apparatus maintained at a constant temperature (24 degrees C). The flame synthesized CNFs showed high degree of H2 adsorption capacities at 100 atm pressure. The highest H2 capacities recorded have been 4.1 wt% [for CNF produced by liquefied petroleum gas (LPG)-Air (E-17)], 3.7 wt% [for nano carbons produced by Methane-Acetylene-Air (EMAC-4)] and 5.04 wt% for [Lithium intercalated sample (Li-EMAC-4)] respectively.

  7. Carbon nanofiber/polyethylene nanocomposite: Processing behavior, microstructure and electrical properties

    International Nuclear Information System (INIS)

    Al-Saleh, Mohammed H.; Gelves, Genaro A.; Sundararaj, Uttandaraman

    2013-01-01

    Highlights: • Electrically conductive CNF/HDPE nanocomposite were prepared by melt compounding. • The effect of processing on the nanocomposites macro and micro structures was analyzed. • 1.4 vol% CNF were required to construct a conductive network within the HDPE matrix. • An EMI SE of 42 dB was reported for 15 vol% CNF/HDPE nanocomposite. • An empirical model was developed to estimate the EMI SE. - Abstract: Electrically conductive polymer nanocomposite of high density polyethylene (HDPE) filled with carbon nanofibers (CNFs) were prepared by melt compounding in a batch mixer. The nanocomposite processing behavior was studied by monitoring the mixing torque vs. time as function of filler content. Scanning electron microscopy and optical microscopy were used to investigate the nanocomposite dispersion of nanofiller and the adhesion between the nanofiller and polymer matrix. The electrical and electromagnetic interference (EMI) shielding behaviors of the nanocomposite were reported as function of nanofibers concentration, and an empirical correlation related the EMI SE to the nanocomposite’s electrical resistivity was developed. Good level of CNF dispersion was evident despite the poor adhesion exhibited between the nanofibers and the HDPE matrix. At 1.5 vol% CNF loading, the nanocomposite exhibited an electrical volume resistivity of 10 5 Ω·cm. EMI shielding effectiveness was found to increase with increase in nanofiller concentration. In the 0.1–1.5 GHz frequency range, 2 mm thick plate made of 5 vol% CNF/HDPE nanocomposite exhibits an EMI shielding effectiveness of 20 dB

  8. INHALATION EXPOSURE TO CARBON NANOTUBES (CNT) AND CARBON NANOFIBERS (CNF): METHODOLOGY AND DOSIMETRY

    Science.gov (United States)

    Oberdörster, Günter; Castranova, Vincent; Asgharian, Bahman; Sayre, Phil

    2015-01-01

    Carbon nanotubes (CNT) and nanofibers (CNF) are used increasingly in a broad array of commercial products. Given current understandings, the most significant life-cycle exposures to CNT/CNF occur from inhalation when they become airborne at different stages of their life cycle, including workplace, use, and disposal. Increasing awareness of the importance of physicochemical properties as determinants of toxicity of CNT/CNF and existing difficulties in interpreting results of mostly acute rodent inhalation studies to date necessitate a reexamination of standardized inhalation testing guidelines. The current literature on pulmonary exposure to CNT/CNF and associated effects is summarized; recommendations and conclusions are provided that address test guideline modifications for rodent inhalation studies that will improve dosimetric extrapolation modeling for hazard and risk characterization based on the analysis of exposure-dose-response relationships. Several physicochemical parameters for CNT/CNF, including shape, state of agglomeration/aggregation, surface properties, impurities, and density, influence toxicity. This requires an evaluation of the correlation between structure and pulmonary responses. Inhalation, using whole-body exposures of rodents, is recommended for acute to chronic pulmonary exposure studies. Dry powder generator methods for producing CNT/CNF aerosols are preferred, and specific instrumentation to measure mass, particle size and number distribution, and morphology in the exposure chambers are identified. Methods are discussed for establishing experimental exposure concentrations that correlate with realistic human exposures, such that unrealistically high experimental concentrations need to be identified that induce effects under mechanisms that are not relevant for workplace exposures. Recommendations for anchoring data to results seen for positive and negative benchmark materials are included, as well as periods for postexposure observation

  9. 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.

  10. 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

  11. Electrospun carboxyl multi-walled carbon nanotubes grafted polyhydroxybutyrate composite nanofibers membrane scaffolds: Preparation, characterization and cytocompatibility.

    Science.gov (United States)

    Zhijiang, Cai; Cong, Zhu; Jie, Guo; Qing, Zhang; Kongyin, Zhao

    2018-01-01

    Electrospun polyhydroxybutyrate (PHB)/carboxyl multi-walled carbon nanotubes grafted polyhydroxybutyrate (CMWCNT-g-PHB) composite nanofibers scaffolds were fabricated by electrospinning technology. The grafted product CMWCNT-g-PHB was prepared by condensation reactions between the carboxyl groups of CMWCNT and hydroxyl groups of PHB molecules and characterized by FTIR, XRD, XPS, TG and TEM measurements. The surface morphology, hydrophilicity and tensile mechanical properties of the electrospun PHB/CMWCNT-g-PHB composite nanofibers membrane scaffolds were investigated. The values of tensile strength, breaking elongation rate, initial modulus and fracture energy of the composite nanofibers scaffolds can reach to 4.64MPa, 255.59%, 88MPa and 109.73kJ/m 2 , respectively. The biodegradability and cytocompatibility of the electrospun composite nanofibers scaffolds were preliminarily evaluated. The as-prepared electrospun PHB/CMWCNT-g-PHB composite nanofibers scaffolds with the characteristics of large specific area, high porosity, good biodegradability and cytocompatibility as well as sufficient mechanical properties should be more promising in the field of tissue engineering scaffolds and biological medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Enhanced Electrochemical Performance of Electrospun Ag/Hollow Glassy Carbon Nanofibers as Free-standing Li-ion Battery Anode

    International Nuclear Information System (INIS)

    Shilpa; Sharma, Ashutosh

    2015-01-01

    Silver with a high theoretical capacity for lithium storage is an attractive alloy based anode for Li-ion batteries, but large volume changes associated with AgLi x alloy formation leads to electrode cracking, pulverization and rapid capacity fading. A buffer matrix, like the electrospun hollow carbon nanofibers, can reduce this problem to a great extent. Herein, we demonstrate the facile synthesis of a free-standing, binder free Ag-C hybrid electrode through co-axial electrospinning, where well dispersed Ag nanoparticles are embedded in hollow carbon nanofibers. Using this approach, the long cycle life of carbon is complemented with the high lithium storage capacity of Ag, resulting in a high performance anode. The Ag-C composite electrode delivers a capacity of 739 mAh g −1 (>conventional graphite anodes) at 50 mA g −1 , with ∼85% capacity retention after 100 cycles. In addition, the Ag-C composite nanofibers are highly porous and exhibit a large accessible surface area (∼726.9 m 2 g −1 ) with an average pore diameter of ∼6.07 nm. The encapsulation of Ag in the hollow interiors not only provides additional lithium storage sites but also enhances the electronic conductivity, which combined with the reduced lithium diffusion path lengths in the nanofibers result in faster charge-discharge kinetics and hence a high rate performance

  13. Effect of thermal interface on heat flow in carbon nanofiber composites.

    Science.gov (United States)

    Gardea, F; Naraghi, M; Lagoudas, D

    2014-01-22

    The thermal transport process in carbon nanofiber (CNF)/epoxy composites is addressed through combined micromechanics and finite element modeling, guided by experiments. The heat exchange between CNF constituents and matrix is studied by explicitly accounting for interface thermal resistance between the CNFs and the epoxy matrix. The effects of nanofiber orientation and discontinuity on heat flow and thermal conductivity of nanocomposites are investigated through simulation of the laser flash experiment technique and Fourier's model of heat conduction. Our results indicate that when continuous CNFs are misoriented with respect to the average temperature gradient, the presence of interfacial resistance does not affect the thermal conductivity of the nanocomposites, as most of the heat flow will be through CNFs; however, interface thermal resistance can significantly alter the patterns of heat flow within the nanocomposite. It was found that very high interface resistance leads to heat entrapment at the interface near to the heat source, which can promote interface thermal degradation. The magnitude of heat entrapment, quantified via the peak transient temperature rise at the interface, in the case of high thermal resistance interfaces becomes an order of magnitude more intense as compared to the case of low thermal resistance interfaces. Moreover, high interface thermal resistance in the case of discontinuous fibers leads to a nearly complete thermal isolation of the fibers from the matrix, which will marginalize the contribution of the CNF thermal conductivity to the heat transfer in the composite.

  14. Highly Graphitic Carbon Nanofibers Web as a Cathode Material for Lithium Oxygen Batteries

    Directory of Open Access Journals (Sweden)

    Hyungkyu Han

    2018-01-01

    Full Text Available The lithium oxygen battery is a promising energy storage system due to its high theoretical energy density and ability to use oxygen from air as a “fuel”. Although various carbonaceous materials have been widely used as a cathode material due to their high electronic conductivity and facial processability, previous studies mainly focused on the electrochemical properties associated with the materials (such as graphene and carbon nanotubes and the electrode configuration. Recent reports demonstrated that the polarization associated with cycling could be significantly increased by lithium carbonates generated from the reaction between the carbon cathode and an electrolyte, which indicates that the physicochemical properties of the carbon cathode could play an important role on the electrochemical performances. However, there is no systematic study to understand these phenomena. Here, we systematically explore the electrochemical properties of carbon nanofibers (CNF webs with different graphitization degree as a cathode for Li oxygen batteries. The physicochemical properties and electrochemical properties of CNF webs were carefully monitored before and after cycling. CNF webs are prepared at 1000, 1200 and 1400 °C. CNF web pyrolyzed at 1400 °C shows lowered polarization and improved cycle retention compared to those of CNF webs pyrolyzed at 1000 and 1200 °C.

  15. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode

    International Nuclear Information System (INIS)

    Kalambate, Pramod K.; Rawool, Chaitali R.; Karna, Shashi P.; Srivastava, Ashwini K.

    2016-01-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (I p ) current for MM is found to be rectilinear in the range 4.0 × 10 −8 –2.0 × 10 −5 M with a detection limit of 7.1 × 10 −9 M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. - Highlights: • Voltammetric sensor for methylergometrine maleate using carbon nanofibers and silver nanoparticle - carbon paste electrode • Wide working range, good reproducibility, fast response and high stability were the main advantages of the proposed sensor • Analysis of methylergometrine maleate in pharmaceutical formulations, urine and blood serum samples • Lowest limit of detection obtained for methylergometrine maleate

  16. 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.

  17. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  19. Surface decoration and dispersibility of carbon nanofibers in aqueous surfactant solution

    Science.gov (United States)

    Wang, B. M.; Zhang, Y.; Liu, S.

    2014-03-01

    As a novel functional nanomaterial, the dispersion effect of carbon nanofibers (CNFs) has a significant influence on the application of CNFs in the composites. Two effective surfactants, methylcellulose (MC) and polycarboxylate superplasticizer, were used to analyze the dispersion of CNFs in aqueous solution. A method utilizing ultrasonic processing was employed to achieve a homogenous CNF suspension, and the dispersion effect was further characterized by the method of measuring ultraviolet absorbency (UV absorbency), zeta potential, surface tension and transmission electron microscopy (TEM) micrographs. The results show that the zeta potential and surface tension reach the saturation plateau at MC concentration and polycarboxylate superplasticizer concentration of about 0.4 and 0.8 g/L, respectively, which reflects that the optimum concentration ratio of MC to CNFs is 2: 1, and the optimum dispersing polycarboxylate superplasticizer to CNFs ratio of 4: 1 is required to achieve dispersions with maximum achievable dispersion of CNFs.

  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. Structural characteristics of carbon nanofibers for on-chip interconnect applications

    International Nuclear Information System (INIS)

    Ominami, Yusuke; Ngo, Quoc; Austin, Alexander J.; Yoong, Hans; Yang, Cary Y.; Cassell, Alan M.; Cruden, Brett A.; Li Jun; Meyyappan, M.

    2005-01-01

    In this letter, we compare the structures of plasma-enhanced chemical vapor deposition of Ni-catalyzed and Pd-catalyzed carbon nanofibers (CNFs) synthesized for on-chip interconnect applications with scanning transmission electron microscopy (STEM). The Ni-catalyzed CNF has a conventional fiberlike structure and many graphitic layers that are almost parallel to the substrate at the CNF base. In contrast, the Pd-catalyzed CNF has a multiwall nanotubelike structure on the sidewall spanning the entire CNF. The microstructure observed in the Pd-catalyzed fibers at the CNF-metal interface has the potential to lower contact resistance significantly, as our electrical measurements using current-sensing atomic force microscopy indicate. A structural model is presented based on STEM image analysis

  2. 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.

  3. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    Science.gov (United States)

    Howser, R. N.; Dhonde, H. B.; Mo, Y. L.

    2011-08-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity.

  4. Self-sensing of carbon nanofiber concrete columns subjected to reversed cyclic loading

    International Nuclear Information System (INIS)

    Howser, R N; Dhonde, H B; Mo, Y L

    2011-01-01

    Civil infrastructures are generally a country's most expensive investment, and concrete is the most widely used material in the construction of civil infrastructures. During a structure's service life, concrete ages and deteriorates, leading to substantial loss of structural integrity and potentially resulting in catastrophic disasters such as highway bridge collapses. A solution for preventing such occurrences is the use of structural health monitoring (SHM) technology for concrete structures containing carbon nanofibers (CNF). CNF concrete has many structural benefits. CNF restricts the growth of nanocracks in addition to yielding higher strength and ductility. Additionally, test results indicate a relationship between electrical resistance and concrete strain, which can be well utilized for SHM. A series of reinforced concrete (RC) columns were built and tested under a reversed cyclic loading using CNF as a SHM device. The SHM device detected and assessed the level of damage in the RC columns, providing a real-time health monitoring system for the structure's overall integrity

  5. The strain sensing property of carbon nanofiber/glass microballoon epoxy nanocomposite

    International Nuclear Information System (INIS)

    Zegeye, Ephraim; Ghamsari, Ali Kadkhoda; Jin, Yoonyoung; Woldesenbet, Eyassu

    2013-01-01

    This work reports the strain sensing property of a nanocomposite made from a free standing multi-scale structure that consisted of glass microballoons and carbon nanofibers. An epoxy system was infiltrated into the structure in order to fabricate a nanocomposite sensor. The electrical resistance of the sensor when subjected to a tensile strain was investigated. The change in electrical resistance of the sensor versus the applied strain was found to have linear and non-linear regions. In the linear region, the sensor exhibited a similar sensitivity to conventional resistance-type strain gages. A single equation that relates the change in electrical resistance to the applied strain for the linear and non-linear regions was developed. (paper)

  6. Face-centered-cubic lithium crystals formed in mesopores of carbon nanofiber electrodes.

    Science.gov (United States)

    Lee, Byoung-Sun; Seo, Jong-Hyun; Son, Seoung-Bum; Kim, Seul Cham; Choi, In-Suk; Ahn, Jae-Pyoung; Oh, Kyu Hwan; Lee, Se-Hee; Yu, Woong-Ryeol

    2013-07-23

    In the foreseeable future, there will be a sharp increase in the demand for flexible Li-ion batteries. One of the most important components of such batteries will be a freestanding electrode, because the traditional electrodes are easily damaged by repeated deformations. The mechanical sustainability of carbon-based freestanding electrodes subjected to repeated electrochemical reactions with Li ions is investigated via nanotensile tests of individual hollow carbon nanofibers (HCNFs). Surprisingly, the mechanical properties of such electrodes are improved by repeated electrochemical reactions with Li ions, which is contrary to the conventional wisdom that the mechanical sustainability of carbon-based electrodes should be degraded by repeated electrochemical reactions. Microscopic studies reveal a reinforcing mechanism behind this improvement, namely, that inserted Li ions form irreversible face-centered-cubic (FCC) crystals within HCNF cavities, which can reinforce the carbonaceous matrix as strong second-phase particles. These FCC Li crystals formed within the carbon matrix create tremendous potential for HCNFs as freestanding electrodes for flexible batteries, but they also contribute to the irreversible (and thus low) capacity of HCNFs.

  7. Highly sensitive voltamperometric determination of pyritinol using carbon nanofiber/gold nanoparticle composite screen-printed carbon electrode

    Directory of Open Access Journals (Sweden)

    Apetrei IM

    2017-07-01

    Full Text Available Irina Mirela Apetrei,1 Constantin Apetrei2 1Department of Pharmaceutical Sciences, Medical and Pharmaceutical Research Center, Faculty of Medicine and Pharmacy, 2Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, “Dunarea de Jos” University of Galati, Galati, Romania Abstract: A novel and highly sensitive electrochemical method for the detection of pyritinol in pharmaceutical products and serum samples has been accomplished based on voltamperometric response of pyritinol in carbon nanofiber-gold nanoparticle (CNF-GNP-modified screen-printed carbon electrode (SPCE. The electrochemical response of pyritinol to CNF-GNP-modified SPCE was studied by cyclic voltammetry and square-wave voltammetry (SWV. Under optimized working conditions, the novel sensor shows excellent voltamperometric response toward pyritinol. The SWV study shows significantly enhanced electrochemical response for pyritinol in CNF-GNP-modified SPCE providing high sensitivity to the novel sensor for pyritinol detection. The peak current for pyritinol is found to be linear with the concentration in the range 1.0×10-8–5.0×10-5 M with a detection limit of 6.23×10-9 M using SWV as the detection method. The viability of the new developed sensor for the analytical purposes was studied by performing experiments on various commercial pharmaceutical products and blood serum samples, which yielded adequate recoveries of pyritinol. The novel electrochemical sensor provides high sensitivity, enhanced selectivity, good reproducibility and practical applicability. Keywords: pyritinol, carbon nanofiber, gold nanoparticle, sensor, square-wave voltammetry

  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. The effects of carbon distribution and thickness on the lithium storage properties of carbon-coated SnO2 hollow nanofibers

    International Nuclear Information System (INIS)

    Zhou, Huimin; Li, Zhiyong; Qiu, Yiping; Xia, Xin

    2016-01-01

    To alleviate the enormous volume change problem of tin-based anodes for lithium ion batteries (LIBs), carbon-coated tin dioxide (SnO 2 ) hollow nanofibers were prepared by means of single-spinneret electrospinning followed by calcination and hydrothermal treatment. By varying the concentration of glucose and the reaction time during the hydrothermal coating process, the final product with different carbon distribution and thickness could be obtained. Galvanostatic charge/discharge was carried out to evaluate them as potential anode materials for LIBs. It was shown that the main effect of carbon distribution was to control the capacity retention rate, and the carbon thickness played the important role in lithium insertion/extraction properties. The optimum composite nanofibers could be prepared with glucose concentration of 10 mg/ml and hydrothermal time of 20 h, the carbon content and the specific surface area of which were 26.15% and 29.4 m 2 /g, respectively. And this anode with both the carbon core and deposited thin carbon skin was able to deliver a high reversible capacity of 704.6 mAhg −1 and the capacity retention could retain 68.2% after 80 cycles. - Graphical abstract: Based on the electrochemical properties of carbon-coated hollow SnO2 anodes, how the carbon distribution and carbon thickness affect their performance are disscussed in groups. - Highlights: • The hollow SnO 2 nanofibers were carbon-coated by hydrothermal process. • The controlled distribution and thickness of carbon layer can be obtained. • The main effect of carbon distribution was to control the capacity retention rate. • The carbon thickness played the important role in lithium insertion/extraction properties.

  10. The effects of carbon distribution and thickness on the lithium storage properties of carbon-coated SnO{sub 2} hollow nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huimin; Li, Zhiyong [College of Textiles and Clothing, Xinjiang University, Xinjiang, Urumqi, 830046 (China); Qiu, Yiping [College of Textiles and Clothing, Xinjiang University, Xinjiang, Urumqi, 830046 (China); College of Textiles and Clothing, Donghua University, Shanghai, 200000 (China); Xia, Xin, E-mail: xjxiaxin@163.com [College of Textiles and Clothing, Xinjiang University, Xinjiang, Urumqi, 830046 (China); College of Textiles and Clothing, Donghua University, Shanghai, 200000 (China)

    2016-06-15

    To alleviate the enormous volume change problem of tin-based anodes for lithium ion batteries (LIBs), carbon-coated tin dioxide (SnO{sub 2}) hollow nanofibers were prepared by means of single-spinneret electrospinning followed by calcination and hydrothermal treatment. By varying the concentration of glucose and the reaction time during the hydrothermal coating process, the final product with different carbon distribution and thickness could be obtained. Galvanostatic charge/discharge was carried out to evaluate them as potential anode materials for LIBs. It was shown that the main effect of carbon distribution was to control the capacity retention rate, and the carbon thickness played the important role in lithium insertion/extraction properties. The optimum composite nanofibers could be prepared with glucose concentration of 10 mg/ml and hydrothermal time of 20 h, the carbon content and the specific surface area of which were 26.15% and 29.4 m{sup 2}/g, respectively. And this anode with both the carbon core and deposited thin carbon skin was able to deliver a high reversible capacity of 704.6 mAhg{sup −1} and the capacity retention could retain 68.2% after 80 cycles. - Graphical abstract: Based on the electrochemical properties of carbon-coated hollow SnO2 anodes, how the carbon distribution and carbon thickness affect their performance are disscussed in groups. - Highlights: • The hollow SnO{sub 2} nanofibers were carbon-coated by hydrothermal process. • The controlled distribution and thickness of carbon layer can be obtained. • The main effect of carbon distribution was to control the capacity retention rate. • The carbon thickness played the important role in lithium insertion/extraction properties.

  11. Versatile nickel–tungsten bimetallics/carbon nanofiber catalysts for direct conversion of cellulose to ethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Zhang, Wen; Yang, Feng; Brown, Dennis E.; Ren, Yang; Lee, Sungsik; Zeng, Dehong; Gao, Qiang; Zhang, Xin

    2016-01-01

    We herein propose a novel synthetic methodology for a series of nickel–tungsten bimetallics/carbon nanofiber catalysts (Ni, 0.37–2.08 wt%; W, 0.01–0.06 wt%) in situ fabricated by pyrolysis (950 °C) of Ni, W and Zn-containing metal organic framework (Ni0.6-x–Wx–ZnBTC, x = 0–0.6) fibers. The resulting catalysts (Ni0.6-x–Wx/CNF) have uniform particles (ca. 68 nm), evenly dispersed onto the hierarchically porous carbon nanofibers formed simultaneously. All of the Ni0.6-x–Wx/CNF catalysts prove to be highly active towards direct conversion of cellulose to ethylene glycol (EG). A large productivity ranging from 15.3 to 70.8 molEG h-1 gW-1 is shown, two orders of magnitude higher than those by using other W-based catalysts reported.

  12. 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.

  13. Carbon nanofibers with highly dispersed tin and tin antimonide nanoparticles: Preparation via electrospinning and application as the anode materials for lithium-ion batteries

    Science.gov (United States)

    Li, Zhi; Zhang, Jiwei; Shu, Jie; Chen, Jianping; Gong, Chunhong; Guo, Jianhui; Yu, Laigui; Zhang, Jingwei

    2018-03-01

    One-dimensional carbon nanofibers with highly dispersed tin (Sn) and tin antimonide (SnSb) nanoparticles are prepared by electrospinning in the presence of antimony-doped tin oxide (denoted as ATO) wet gel as the precursor. The effect of ATO dosage on the microstructure and electrochemical properties of the as-fabricated Sn-SnSb/C composite nanofibers is investigated. Results indicate that ATO wet gel as the precursor can effectively improve the dispersion of Sn nanoparticles in carbon fiber and prevent them from segregation during the electrospinning and subsequent calcination processes. The as-prepared Sn-SnSb/C nanofibers as the anode materials for lithium-ion batteries exhibit high reversible capacity and stable cycle performance. Particularly, the electrode made from Sn-SnSb/C composite nanofibers obtained with 0.9 g of ATO gel has a high specific capacity of 779 mAh·g-1 and 378 mAh·g-1 at the current density of 50 mA·g-1 and 5 A·g-1, respectively, and it exhibits a capacity retention of 97% after 1200 cycles under the current density of 1 A·g-1. This is because the carbon nanofibers can form a continuous conductive network to buffer the volume change of the electrodes while Sn and Sn-SnSb nanoparticles uniformly distributed in the carbon nanofibers are free of segregation, thereby contributing to electrochemical performances of the electrodes.

  14. 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.

  15. 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.

  16. Enhanced electrical capacitance of porous carbon nanofibers derived from polyacrylonitrile and boron trioxide

    International Nuclear Information System (INIS)

    Kim, Bo-Hye; Yang, Kap Seung

    2013-01-01

    Carbon nanofibers (CNFs) containing boron and nitrogen are prepared from polyacrylonitrile and boron trioxide (B 2 O 3 ) by using simple electrospinning. The B 2 O 3 introduction into a PAN solution causes a porous structure with stabilized [O]BN functional groups to develop in the processes of stabilization and carbonization. The pore structure and the functional groups such as B atoms and [O]BN introduce synergistic effects by not only increasing the power density but also the energy density, as shown by the results. The energy storage capabilities of the electrode prepared from 20 wt% B 2 O 3 added to the PAN solution are as follows: a capacitance of 184.0 F g −1 and an energy density of 18.7–25.2 Wh kg −1 in the respective power density range of 400–10,000 W kg −1 in 6 M KOH electrolyte. Hence, these CNFs exhibit a very promising potential as electrode materials for electrical double-layer capacitors due to their unique microstructure and proper proportion of heteroatoms

  17. Mechanical performance of HMA-2 modified with purified and unpurified carbon nanotubes and nanofibers

    Directory of Open Access Journals (Sweden)

    Mario Rodrigo Rubio

    2017-05-01

    Full Text Available The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2 modified with carbon nanotubes and carbon nanofibers (CNTF. CNTF were made by means the Catalytic Vapor Deposition (CVD technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1 HMA-2 modified with purified CNTF; 2 HMA-2 modified with non-purified CNTF and, 3 a Conventional HMA-2 (control. Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatiguerelated issues and improve the long-term durability of flexible pavements.

  18. 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.

  19. 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.

  20. Glass fiber supports modified by layers of silica and carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Popov Maxim V.

    2017-04-01

    Full Text Available The new multi-layered composite was manufactured by deposition of the carbon nanofibers (CNF at the surface of the glass-fiber fabric, which is pre-modified by application of additional external layers of NiO and porous silica. Carbonization of synthesized catalytic template was performed at 450 °C in propanebutane media at ambient pressure. CNF was deposited in amount of ~130% of initial template mass or 65 g per g of nickel, the specific surface area of the material is ~100 m2/g. The synthesized material has high mechanical strength, high hydrophobicity and strong bonding between CNF and glass-fiber support. The synthesis method is technologically simple, inexpensive and easily scalable. It is possible to manufacture such material in various solid shapes, using the flexibility of the primary glass-fiber support; in particular, it may be used for production of the mechanically self-sustainable catalytic cartridges with required shape and internal geometry using no additional structuring elements.

  1. Co- and defect-rich carbon nanofiber films as a highly efficient electrocatalyst for oxygen reduction

    Science.gov (United States)

    Kim, Il To; Song, Myeong Jun; Shin, Seoyoon; Shin, Moo Whan

    2018-03-01

    Many efforts are continuously devoted to developing high-efficiency, low-cost, and highly scalable oxygen reduction reaction (ORR) electrocatalysts to replace precious metal catalysts. Herein, we successfully synthesize Co- and defect-rich carbon nanofibers (CNFs) using an efficient heat treatment approach involving the pyrolysis of electrospun fibers at 370 °C under air. The heat treatment process produces Co-decorated CNFs with a high Co mass ratio, enriched pyridinic N, Co-pyridinic Nx clusters, and defect-rich carbon structures. The synergistic effects from composition and structural changes in the designed material increase the number of catalytically active sites for the ORR in an alkaline solution. The prepared Co- and defect-rich CNFs exhibit excellent ORR activities with a high ORR onset potential (0.954 V vs. RHE), a large reduction current density (4.426 mA cm-2 at 0.40 V), and a nearly four-electron pathway. The catalyst also exhibits a better long-term durability than commercial Pt/C catalysts. This study provides a novel hybrid material as an efficient ORR catalyst and important insight into the design strategy for CNF-based hybrid materials as electrochemical electrodes.

  2. 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.

  3. Effect of filler geometry on coefficient of thermal expansion in carbon nanofiber reinforced epoxy composites.

    Science.gov (United States)

    Cho, M; Jang, J; Suhr, J

    2011-02-01

    This study involves the investigation of the geometry effect of nano-fillers on thermally induced dimensional stability of epoxy composites by experimentally evaluating the linear coefficient of thermal expansion (CTE). Carbon nanofibers (CNF) were chosen as the filler in epoxy matrix to investigate the effect of an aspect ratio on the CTE of the nanocomposites at three different volume fractions of 0.5, 1, and 2% of the nano-filler. The composites were fabricated using a mechanical mixing method. The CTE values were evaluated by measuring thermal strains of the composites and also compared with a micromechanics model. It was observed that the composites with short CNF (average L/d = 10) show better thermal stability than one of the composites with long CNF (average L/d = 70), and the thermal stability of the composites was proportional to the volume fraction of the filler in each composite. In addition, the CTE of mutliwalled carbon nanotubes (MWNT) reinforced epoxy composites was evaluated and compared with the CTE of the CNF reinforced composites. Interestingly, the MWNT reinforced composites show the greatest thermal stability with an 11.5% reduction in the CTE over the pure epoxy. The experimental data was compared with micromechanics model.

  4. 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.

  5. 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.

  6. Highest recorded electrical conductivity and microstructure in polypropylene-carbon nanotubes composites and the effect of carbon nanofibers addition

    Science.gov (United States)

    Ramírez-Herrera, C. A.; Pérez-González, J.; Solorza-Feria, O.; Romero-Partida, N.; Flores-Vela, A.; Cabañas-Moreno, J. G.

    2018-04-01

    In the last decade, numerous investigations have been devoted to the preparation of polypropylene-multiwalled carbon nanotubes (PP/MWCNT) nanocomposites having enhanced properties, and in particular, high electrical conductivities (> 1 S cm-1). The present work establishes that the highest electrical conductivity in PP/MWCNT nanocomposites is limited by the amount of nanofiller content which can be incorporated in the polymer matrix, namely, about 20 wt%. This concentration of MWCNT in PP leads to a maximum electrical conductivity slightly lower than 8 S cm-1, but only by assuring an adequate combination of dispersion and spatial distribution of the carbon nanotubes. The realization of such an optimal microstructure depends on the characteristics of the production process of the PP/MWCNT nanocomposites; in our experiments, involving composite fabrication by melt mixing and hot pressing, a second re-processing cycle is shown to increase the electrical conductivity values by up to two orders of magnitude, depending on the MWCNT content of the nanocomposite. A modest increase of the highest electrical conductivity obtained in nanocomposites with 21.5 wt% MWCNT content has been produced by the combined use of carbon nanofibers (CNF) and MWCNT, so that the total nanofiller content was increased to 30 wt% in the nanocomposite with PP—15 wt% MWCNT—15 wt%CNF.

  7. Characterization and recovery of shape memory polymers filled with carbon nanofibers

    Science.gov (United States)

    Powers, Daniel Stephen

    The microstructure and shape memory properties of polymers utilizing two different shape memory processes reinforced with vapor grown carbon nanofibers (CNFs) were investigated by thermal and thermomechanical techniques. The first shape memory polymer (SMP) was a thermoplastic polyurethane elastomer (Irogran) that used strain-induced crystallization for locking in the deformation. Shape recovery occurred through the melting temperature of the crystallites and demonstrated relatively good shape memory properties. Both shape fixity (ability to lock in the deformation) and recovery time (how fast the material recovered back to its original shape) improved with carbon nanofiber loading; however, the percent recovery (ability to return back to its original shape) decreased with CNF loading. Initial studies verified the role of strain-induced crystallization. Solid-state proton nuclear magnetic resonance (NMR) was used to investigate the impact of CNFs on the structure and dynamics of the crystallites in this thermoplastic polyurethane elastomer (TPE). The introduction of CNFs led to a shifting and broadening of the spectra, where the magnitude of the induced shifts and line broadening increased with CNF concentration. The spin-lattice and spin-spin relaxation times were not significantly changed with the introduction of CNFs. This demonstrated that the line broadening was inhomogeneous and a consequence of the magnetic susceptibility of the CNFs and not a reduction in segment mobility due to the proximity of the CNF surface. Spin diffusion experiments provided additional insight into the strain induced structure of the TPE/CNF composites. The second SMP was a thermoset epoxy (TEMBO DP5.1) reinforced with CNFs. This SMP used vitrification through the glass transition temperature for locking in the deformation and demonstrated excellent shape memory properties. The morphology of the CNFs throughout the epoxy polymer matrix, along with the recovery times of the

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

    Science.gov (United States)

    Song, Zhenyu; Hou, Xiaoxiao; Zhang, Liqun; Wu, Sizhu

    2011-01-01

    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. PMID:28879944

  9. 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.

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

    Science.gov (United States)

    Song, Zhenyu; Hou, Xiaoxiao; Zhang, Liqun; Wu, Sizhu

    2011-04-06

    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.

  11. A heart-coronary arteries structure of carbon nanofibers/graphene/silicon composite anode for high performance lithium ion batteries.

    Science.gov (United States)

    Ma, Xiaoxin; Hou, Guangmei; Ai, Qing; Zhang, Lin; Si, Pengchao; Feng, Jinkui; Ci, Lijie

    2017-08-29

    In an animal body, coronary arteries cover around the whole heart and supply the necessary oxygen and nutrition so that the heart muscle can survive as well as can pump blood in and out very efficiently. Inspired by this, we have designed a novel heart-coronary arteries structured electrode by electrospinning carbon nanofibers to cover active anode graphene/silicon particles. Electrospun high conductive nanofibers serve as veins and arteries to enhance the electron transportation and improve the electrochemical properties of the active "heart" particles. This flexible binder free carbon nanofibers/graphene/silicon electrode consists of millions of heart-coronary arteries cells. Besides, in the graphene/silicon "hearts", graphene network improves the electrical conductivity of silicon nanopaticles, buffers the volume change of silicon, and prevents them from directly contacting with electrolyte. As expected, this novel composite electrode demonstrates excellent lithium storage performance with a 86.5% capacity retention after 200 cycles, along with a high rate performance with a 543 mAh g -1 capacity at the rate of 1000 mA g -1 .

  12. Thermoelectric properties of carbon nanotube and nanofiber based ethylene-octene copolymer composites for thermoelectric devices, Journal of Nanomaterials

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Olejník, J.; Kovář, M.; Svoboda, P.

    2013-01-01

    Roč. 2013, August (2013) ISSN 1687-4110 Grant - others:TBU Zlin(CZ) iga/ft/2013/018; GA MŠk(CZ) EE.2.3.20.0104; GA MŠk(CZ) ED2.1.00/03.0111 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : CNF * carbon nanotubes * carbon nanofibers * power-factor * nanocomposites * behavior * network Subject RIV: BK - Fluid Dynamics Impact factor: 1.611, year: 2013 http://www.hindawi.com/journals/jnm/2013/792875/

  13. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    Science.gov (United States)

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2015-07-01

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. This is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.

  14. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Brian L. [Univ. of Texas, Dallas, TX (United States); Martinez, Patricia [Univ. of Texas, Dallas, TX (United States); Zakhidov, Anvar A. [Univ. of Texas, Dallas, TX (United States); Shaner, Eric A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Mark [Univ. of Texas, Dallas, TX (United States)

    2015-07-06

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. Finally, this is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.

  15. 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.

  16. Stable Fe nanomagnets encapsulated inside vertically-aligned carbon nanotubes.

    Science.gov (United States)

    Bondino, Federica; Magnano, Elena; Ciancio, Regina; Castellarin Cudia, Carla; Barla, Alessandro; Carlino, Elvio; Yakhou-Harris, Flora; Rupesinghe, Nalin; Cepek, Cinzia

    2017-12-06

    Well-defined sized (5-10 nm) metallic iron nanoparticles (NPs) with body-centered cubic structure encapsulated inside the tip of millimeter-long vertically aligned carbon nanotubes (VACNTs) of uniform length have been investigated with high-resolution transmission electron microscopy and soft X-ray spectroscopy techniques. Surface-sensitive and chemically-selective measurements have been used to evaluate the magnetic properties of the encapsulated NPs. The encapsulated Fe NPs display magnetic remanence up to room temperature, low coercivity, high chemical stability and no significant anisotropy. Our surface-sensitive measurements combined with the specific morphology of the studied VACNTs allow us to pinpoint the contribution of the surface oxidized or hydroxidized iron catalysts present at the VACNT-substrate interface.

  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. 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.

  19. Carbon Nanofibers-Poly-3-hydroxyalkanoates Nanocomposite: Ultrasound-Assisted Dispersion and Thermostructural Properties

    Directory of Open Access Journals (Sweden)

    A. M. Gumel

    2014-01-01

    Full Text Available The conductivity and high surface-to-volume ratio of carbon nanofibers (CNFs composited with the medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA have attracted much attention as smart biomaterial. However, poor CNF dispersion leads to tactoid agglomerated composite with poor crystallite morphology resulting in inferior thermomechanical properties. We employed acoustic sonication to enhance the construction of exfoliated PHA/CNFs nanocomposites. The effects of CNF loading and the insonation variables (power intensity, frequency, and time on the stability and microscopic morphology of the nanocomposites were studied. Sonication improved the dispersion of CNFs into the polymer matrix, thereby improving the physical morphology, crystallinity, and thermomechanical properties of the nanocomposites. For example, compositing the polymer with 10% w/w CNF resulted in 66% increase in crystallite size, 46% increase in micromolecular elastic strain, and 17% increase in lattice strain. Nevertheless, polymer degradation was observed following the ultrasound exposure. The constructed bionanocomposite could potentially be applied for organic electroconductive materials, biosensors and stimuli-responsive drug delivery devices.

  20. Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires for lithium ion batteries

    Science.gov (United States)

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-01-01

    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. PMID:25944615

  1. Edge-Oriented Graphene on Carbon Nanofiber for High-Frequency Supercapacitors

    Science.gov (United States)

    Islam, Nazifah; Warzywoda, Juliusz; Fan, Zhaoyang

    2018-03-01

    High-frequency supercapacitors are being studied with the aim to replace the bulky electrolytic capacitors for current ripple filtering and other functions used in power systems. Here, 3D edge-oriented graphene (EOG) was grown encircling carbon nanofiber (CNF) framework to form a highly conductive electrode with a large surface area. Such EOG/CNF electrodes were tested in aqueous and organic electrolytes for high-frequency supercapacitor development. For the aqueous and the organic cell, the characteristic frequency at - 45° phase angle was found to be as high as 22 and 8.5 kHz, respectively. At 120 Hz, the electrode capacitance density was 0.37 and 0.16 mF cm-2 for the two cells. In particular, the 3 V high-frequency organic cell was successfully tested as filtering capacitor used in AC/DC converter, suggesting the promising potential of this technology for compact power supply design and other applications. [Figure not available: see fulltext.

  2. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

    International Nuclear Information System (INIS)

    Borrell, Amparo; García-Moreno, Olga; Torrecillas, Ramón; García-Rocha, Victoria; Fernández, Adolfo

    2012-01-01

    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. Graphitic carbon nitride nanofibers in seaweed-like architecture for gas chromatographic separations.

    Science.gov (United States)

    Zheng, Yunzhong; Han, Qing; Qi, Meiling; Qu, Liangti

    2017-05-05

    Seaweed-like graphitic carbon nitride (g-C 3 N 4 ) has a unique porous architecture composed of interlocking g-C 3 N 4 nanofibers (NF-C 3 N 4 ) with much higher surface area than bulk g-C 3 N 4 and shows good potential in separation science. This work investigated the separation performance of NF-C 3 N 4 as stationary phase for capillary gas chromatographic (GC) separations. The NF-C 3 N 4 column exhibits weak polarity and high column efficiency of 4728 plates/m for n-dodecane. Importantly, it displays good separation performance for a wide range of analytes and shows different retention behaviors from the bulk g-C 3 N 4 column and commercial HP-5MS column with 5% phenylpolysiloxane. Particularly, it shows high resolving capability for both aliphatic and aromatic isomers. In addition, NF-C 3 N 4 column has high thermal stability up to 280°C and good separation repeatability with relative standard deviation (RSD) values in the range of 0.29-0.61% for intra-day, 0.56-1.1% for inter-day and 2.0-4.9% for between-column, respectively. Moreover, it was applied for the determination of isomer impurities in real samples, showing good potential in GC applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Pyrolytic Carbon Coatings on Aligned Carbon Nanotube Assemblies and Fabrication of Advanced Carbon Nanotube/Carbon Composites

    Science.gov (United States)

    Faraji, Shaghayegh

    Chemical vapor deposition (CVD) is a technique used to create a pyrolytic carbon (PyC) matrix around fibrous preforms in carbon/carbon (C/C) composites. Due to difficulties in producing three-dimensional carbon nanotube (CNT) assemblies, use of nanotubes in CVD fabricated CNT/C composites is limited. This dissertation describes efforts to: 1) Study the microstructure of PyC deposited on CNTs in order to understand the effect of microstructure and morphology of carbon coatings on graphitization behavior of CNT/PyC composites. This understanding helped to suggest a new approach for controlled radial growth of CNTs. 2) Evaluate the properties of CNT/PyC structures as a novel form of CNT assemblies with resilient, anisotropic and tunable properties. PyC was deposited on aligned sheets of nanotubes, drawn from spinnable CNT arras, using CVD of acetylene gas. At longer deposition times, the microstructure of PyC changed from laminar turbostratic carbon to a disordered carbon. For samples with short PyC deposition times (up to 30 minutes), deposited carbon layer rearranged during graphitization treatment and resulted in a crystalline structure where the coating and original tube walls could not be easily differentiated. In contrast, in samples with longer carbon deposition durations, carbon layers close to the surface of the coating remained disordered even after graphitization thermal treatment. Understanding the effect of PyC microstructure transition on graphitization behavior of CNT/PyC composites was used to develop a new method for controlled radial growth of CNTs. Carbon coated aligned CNT sheets were graphitized after each short (20 minutes) carbon deposition cycle. This prevented development of disorder carbon during subsequent PyC deposition cycles. Using cyclic-graphitization method, thick PyC coating layers were successfully graphitized into a crystalline structure that could not be differentiated from the original nanotube walls. This resulted into radial

  5. Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability

    Directory of Open Access Journals (Sweden)

    Velmurugan Thavasi

    2009-01-01

    Full Text Available We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness.

  6. Aligned Carbon Nanotubes for High-Performance Films and Composites

    Science.gov (United States)

    Zhang, Liwen

    Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or

  7. Efficient strategy to Cu/Si catalyst into vertically aligned carbon ...

    Indian Academy of Sciences (India)

    Vertically aligned carbon nanotubes; drop cast method; electron microscopes; electrical properties. Abstract. Bamboo-shaped vertically aligned carbon nanotubes (bs-VACNTs) were fabricated on Cu/Si catalyst by chemical vapour deposition (CVD) technique under the atmospheric pressure. The catalytic material (Cu/Si) ...

  8. Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique

    Directory of Open Access Journals (Sweden)

    Nicolás Díaz Silva

    2017-01-01

    Full Text Available Carbon nanohybrid material (CNF/γ-Fe2O3 was obtained via a modified sol-gel technique consisting of two steps: functionalization of carbon nanofibers (CNF in H2SO4/HNO3 followed by synthesis using Fe(NO33∙9H2O. As a result, the iron content of the CNF/γ-Fe2O3 was increased by more than twice from about 40% to about 87% mass percent, compared to the pristine CNF and oxidized CNF specimens, as proved by energy dispersive X-ray fluorescence. Scanning electron microscopy images exhibited “cumulus” on the CNF/γ-Fe2O3 specimen surface, which showed the highest iron mass percentage, proved by energy dispersive X-ray spectroscopy. Transmission electron microscopy images confirmed attachment of γ-Fe2O3 cumulus to the inner and outer surfaces of the CNF walls after synthesis. The characteristic peaks of Fe 2p3/2 and Fe 2p1/2 appeared in the XPS spectra obtained on CNF/γ-Fe2O3. In addition, X-ray diffraction (XRD results indicated formation of γ-Fe2O3 during the synthesis process. The Raman spectrum of the CNF/γ-Fe2O3 sample displays peaks with positions close to characteristic peaks of highly crystalline and monodisperse maghemite nanocrystallites. The synthesis of CNF/γ-Fe2O3 leads to an increase in the hydrophilicity of CNF and magnetic properties at room temperature.

  9. Synthesis of Highly Conductive, Uniformly Silver-Coated Carbon Nanofibers by Electroless Deposition.

    Science.gov (United States)

    Cauchy, Xavier; Klemberg-Sapieha, Jolanta-Ewa; Therriault, Daniel

    2017-08-30

    Noble-metal-coated carbon-based nanoparticles, when used as electrically conductive fillers, have the potential to provide excellent conductivity without the high weight and cost normally associated with metals such as silver and gold. To this effect, many attempts were made to deposit uniform metallic layers on core nanoparticles with an emphasis on silver for its high conductivity. The results so far were disheartening with the metal morphology being better described as a decoration than a coating with small effects on the electrical conductivity of the bulk particles. We tackled in this work the specific problem of electroless deposition of silver on carbon nanofibers (CNFs) with the investigation of every step of the process. We performed X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM, SEM), zeta potential, and electrical conductivity measurements to identify a repeatable, reliable set of parameters allowing for a uniform and fully connected silver deposition on the surface of the CNFs. The bulk particles' specific electrical conductivity (conductivity per unit mass) undergoes a more than 10-fold increase during the deposition, reaching 2500 S·cm 2 /g, which indicates that the added metal mass participates efficiently to the conduction network. The particles keep their high aspect ratio through the process, which enables a percolated conduction network at very low volume loadings in a composite. No byproducts are produced during the reaction so the particles do not have to be sorted or purified and can be used as produced after the short ∼15 min reaction time. The particles might be an interesting replacement to conventional fillers in isotropic conductive adhesives, as a conductive network is obtained at a much lower loading. They might also serve as electrically conductive fillers in composites where a high conductivity is needed, such as lightning strike protection systems, or as high surface area silver

  10. High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Al-Enizi, Abdullah M. [Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia); Elzatahry, Ahmed A., E-mail: aelzatahry@ksu.edu.sa [Materials Science and Technology Program, College of Arts and Science, Qatar University, Doha 2713 (Qatar); Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Alexandria 21934 (Egypt); Abdullah, Aboubakr M., E-mail: bakr@qu.edu.qa [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Vinu, Ajayan [Future Industries Institute, University of South Australia, Building X-X2-09, Mawson Lakes Campus, Mawson Lakes 5095 SA (Australia); Iwai, Hideo [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 (Japan); Al-Deyab, Salem S. [Petrochemical Research Chair, Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia)

    2017-04-15

    Highlights: • A mixture of Polyvinylpyrrolidone (PVP), graphene and emeraldine base polyaniline (PANi) was electrospun and used as starting materials to prepare a nitrogen-doped carbon nanofiber (N-CNF). • Nickel oxide was loaded on the N-CNF to form a nanocomposite which was calcined later at different temperatures. • The effect of calcination temperature on the electrocatalytic behavior of the nanocomposite was studied which shows that the nanocomposite calcined at 500 °C was proved to be very high compared to the other calcination temperatures. • The stability of catalyst was excellent and its resistance to the adsorption of the intermediates generated from the methanol oxidation was very high. - Abstract: 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 m{sup 2} g{sup −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.

  11. Cellulose nanofiber/single-walled carbon nanotube hybrid non-woven macrofiber mats as novel wearable supercapacitors with excellent stability, tailorability and reliability

    Science.gov (United States)

    Niu, Qingyuan; Gao, Kezheng; Shao, Ziqiang

    2014-03-01

    Non-woven macrofiber mats are prepared by simply controlling the extrusion patterns of cellulose nanofiber/single-walled carbon nanotube suspensions in an ethanol coagulation bath, and drying in air under restricted conditions. These novel wearable supercapacitors based on non-woven macrofiber mats are demonstrated to have excellent tailorability, electrochemical stability, and damage reliability.Non-woven macrofiber mats are prepared by simply controlling the extrusion patterns of cellulose nanofiber/single-walled carbon nanotube suspensions in an ethanol coagulation bath, and drying in air under restricted conditions. These novel wearable supercapacitors based on non-woven macrofiber mats are demonstrated to have excellent tailorability, electrochemical stability, and damage reliability. Electronic supplementary information (ESI) available: Experimental, TEM image, IR spectra, and XRD spectra of cellulose nanofibers, photograph of the cellulose nanofiber/single-walled carbon nanotube suspension, cellulose nanofiber/single-walled carbon nanotube non-woven macrofiber mat and non-woven macrofiber mat wearable supercapacitors. The electrochemical performance of the CNF/SWCNT hybrid fiber wearable supercapacitor. Photograph of the non-woven macrofiber mat wearable supercapacitors integrated within textiles. See DOI: 10.1039/c3nr05929d

  12. Carbon dot/polyvinylpyrrolidone hybrid nanofibers with efficient solid-state photoluminescence constructed using an electrospinning technique

    Science.gov (United States)

    Zhai, Yue; Bai, Xue; Cui, Haining; Zhu, Jinyang; Liu, Wei; Zhang, Tianxiang; Dong, Biao; Pan, Gencai; Xu, Lin; Zhang, Shuang; Song, Hongwei

    2018-01-01

    Carbon dots (CDs) are the promising candidates for application in optoelectronic and biological areas due to their excellent photostability, unique photoluminescence, good biocompatibility, low toxicity and chemical inertness. However, the self-quenching of photoluminescence as they are dried into the solid state dramatically limits their further application. Therefore, realizing efficient photoluminescence and large-scale production of CDs in the solid state is an urgent challenge. Herein, solid-state hybrid nanofibers based on CDs and polyvinylpyrrolidone (PVP) are constructed through an electrospinning process. The resulting solid-state hybrid PVP/CD nanofibers present much enhanced photoluminescence performance compared to the corresponding pristine colloidal CDs due to the decrease in non-radiative recombination of electron-holes. Owing to the suppressed self-quenching of CDs, the photoluminescence quantum yield is considerably improved from 42.9% of pristine CDs to 83.5% of nanofibers under the excitation wavelength of 360 nm. This has great application potential in optical or optoelectronic devices.

  13. Local and broadband photovoltaic response of aligned carbon nanotube films

    Science.gov (United States)

    Nanot, Sebastien; Morris, Darius; Hendricks, Lisa A.; Kono, Junichiro; Pint, Cary; Hauge, Robert H.; Leonard, Francois

    2012-02-01

    Although individual semiconducting single-walled carbon nanotubes (SWCNT) have exhibited clear photovoltaic responses, it remains unclear whether macroscopic films of carbon nanotubes can also behave this way. While some groups have explained finite photovoltages as Schottky barrier effects, other groups have proposed photo-thermoelectric effects in suspended films. Here, we have studied highly aligned SWCNT films that work well as photovoltaics. SWCNTs grown by CVD were transferred onto a SiO2 substrate. There was a broad diameter distribution in the films to obtain a large wavelength range of interband absorption. The films were top-contacted with various metals. We made a systematic scanning photocurrent study of such samples at 660 and 1350 nm. A strong local photovoltage appeared at electrode-SWCNT interfaces. Detailed comparison with theoretical calculations of the dependence of photo-response on the nanotube orientation, metal electrode type, and temperature unambiguously revealed the photovoltaic nature of the observed photovoltage. We assign these effects to the doping of both metallic and semiconducting SWCNTs under the electrodes, in a similar fashion to graphene, its lineshape being determined by the diffusion of photoexcited carriers. Finally, to obtain a finite net signal under global illumination, we utilized different electrode combinations and studied their photoresponses from the visible up to mid-infrared and terahertz.

  14. Membranes of MnO Beading in Carbon Nanofibers as Flexible Anodes for High-Performance Lithium-Ion Batteries

    Science.gov (United States)

    Zhao, Xin; Du, Yuxuan; Jin, Lei; Yang, Yang; Wu, Shuilin; Li, Weihan; Yu, Yan; Zhu, Yanwu; Zhang, Qinghua

    2015-01-01

    Freestanding yet flexible membranes of MnO/carbon nanofibers are successfully fabricated through incorporating MnO2 nanowires into polymer solution by a facile electrospinning technique. During the stabilization and carbonization processes of the as-spun membranes, MnO2 nanowires are transformed to MnO nanoparticles coincided with a conversion of the polymer from an amorphous state to a graphitic structure of carbon nanofibers. The hybrids consist of isolated MnO nanoparticles beading in the porous carbon and demonstrate superior performance when being used as a binder-free anode for lithium-ion batteries. With an optimized amount of MnO (34.6 wt%), the anode exhibits a reversible capacity of as high as 987.3 mAh g−1 after 150 discharge/charge cycles at 0.1 A g−1, a good rate capability (406.1 mAh g−1 at 3  A g−1) and an excellent cycling performance (655 mAh g−1 over 280 cycles at 0.5 A g−1). Furthermore, the hybrid anode maintains a good electrochemical performance at bending state as a flexible electrode. PMID:26374601

  15. Modeling to study the role of catalyst in the formation of graphitic shells during carbon nanofiber growth subjected to reactive plasma

    Science.gov (United States)

    Gupta, Ravi; Gupta, Neha; Sharma, Suresh C.

    2018-04-01

    An analytical model to study the role of a metal catalyst nanofilm in the nucleation, growth, and resulting structure of carbon nanofibers (CNFs) in low-temperature hydrogen diluted acetylene plasma has been developed. The model incorporates the nanostructuring of thin catalyst films, growth of CNF, restructuring of catalyst nanoparticles during growth, and its repercussion on the resulting structure (alignment of rolled graphene sheets around catalyst nanoparticles) by taking into account the plasma sheath formalization, kinetics of neutrals and positively charged species in the reactive plasma, flux of plasma species onto the catalyst front surface, and numerous surface reactions for carbon generation. In order to examine the influence of the catalyst film on the growth of CNFs, the numerical solutions of the model equations have been obtained for experimentally determined initial conditions and glow discharge plasma parameters. From the solutions obtained, we found that nanostructuring of thin films leads to the formation of small nanoparticles with high surface number density. The CNF nucleates over these small-sized nanoparticles grow faster and attain early saturation because of the quick poisoning of small-sized catalyst particles, and contain only a few graphitic shells. However, thick nanofilms result in shorter CNFs with large diameters composed of many graphitic shells. Moreover, we found that the inclination of graphitic shells also depends on the extent up to which the catalyst can reconstruct itself during the growth. The small nanoparticles show much greater elongation along the growth axis and also show a very small difference between their tip and base diameter during the growth due to which graphitic shells align at very small angles as compared to the larger nanoparticles. The present study is useful to synthesize the thin and more extended CNFs/CNTs having a smaller opening angle (inclination angle of graphene layers) as the opening angle has a

  16. High performance transistors via aligned polyfluorene-sorted carbon nanotubes

    International Nuclear Information System (INIS)

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S.

    2014-01-01

    We evaluate the performance of exceptionally electronic-type sorted, semiconducting, aligned single-walled carbon nanotubes (s-SWCNTs) in field effect transistors (FETs). High on-conductance and high on/off conductance modulation are simultaneously achieved at channel lengths which are both shorter and longer than individual s-SWCNTs. The s-SWCNTs are isolated from heterogeneous mixtures using a polyfluorene-derivative as a selective agent and aligned on substrates via dose-controlled, floating evaporative self-assembly at densities of ∼50 s-SWCNTs μm −1 . At a channel length of 9 μm the s-SWCNTs percolate to span the FET channel, and the on/off ratio and charge transport mobility are 2.2 × 10 7 and 46 cm 2  V −1  s −1 , respectively. At a channel length of 400 nm, a large fraction of the s-SWCNTs directly span the channel, and the on-conductance per width is 61 μS μm −1 and the on/off ratio is 4 × 10 5 . These results are considerably better than previous solution-processed FETs, which have suffered from poor on/off ratio due to spurious metallic nanotubes that bridge the channel. 4071 individual and small bundles of s-SWCNTs are tested in 400 nm channel length FETs, and all show semiconducting behavior, demonstrating the high fidelity of polyfluorenes as selective agents and the promise of assembling s-SWCNTs from solution to create high performance semiconductor electronic devices

  17. High performance transistors via aligned polyfluorene-sorted carbon nanotubes

    Science.gov (United States)

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S.

    2014-02-01

    We evaluate the performance of exceptionally electronic-type sorted, semiconducting, aligned single-walled carbon nanotubes (s-SWCNTs) in field effect transistors (FETs). High on-conductance and high on/off conductance modulation are simultaneously achieved at channel lengths which are both shorter and longer than individual s-SWCNTs. The s-SWCNTs are isolated from heterogeneous mixtures using a polyfluorene-derivative as a selective agent and aligned on substrates via dose-controlled, floating evaporative self-assembly at densities of ˜50 s-SWCNTs μm-1. At a channel length of 9 μm the s-SWCNTs percolate to span the FET channel, and the on/off ratio and charge transport mobility are 2.2 × 107 and 46 cm2 V-1 s-1, respectively. At a channel length of 400 nm, a large fraction of the s-SWCNTs directly span the channel, and the on-conductance per width is 61 μS μm-1 and the on/off ratio is 4 × 105. These results are considerably better than previous solution-processed FETs, which have suffered from poor on/off ratio due to spurious metallic nanotubes that bridge the channel. 4071 individual and small bundles of s-SWCNTs are tested in 400 nm channel length FETs, and all show semiconducting behavior, demonstrating the high fidelity of polyfluorenes as selective agents and the promise of assembling s-SWCNTs from solution to create high performance semiconductor electronic devices.

  18. Measurement of Vertically Aligned Carbon Nanotube Array Compression Response

    Science.gov (United States)

    Cao, Changhong

    The use of carbon nanotubes (CNTs) in the form of vertically aligned arrays or films has been of interest due to the super-compressible response and the ability to be used as electrical and thermal contacts. CNT arrays have shown the remarkable ability to react as foam-like structures and exhibit localized, coordinated buckling within specific regions. An understanding of the buckling region evolution and the resulting effects on the bulk CNT array response are important, unanswered fundamental questions necessary for the future application of CNT arrays. Here, we report on the low-cycle compression of bulk vertically aligned CNT arrays to observe initiation and growth of the buckling as a function of compressive strain and the contacting substrate material. A critical strain of ˜5.5% is found above which the buckling region length increased and below which remained at or below the applied strain. The results are corroborated with nanoindentation on the surfaces, which indicate a stiffening of the near surface by 9.4%-16.5% with increasing applied strain. Also, contact counterfaces with different stiffness, lithium niobate and a polymer gel, were compared, which resulted in changes of ˜32% in total array height after cyclic compression. Raman spectroscopy on CNT arrays before and after compressive deformation was performed observing repeatable vibrational shifts in the strained regions. Also, to observe the applicability of CNT arrays as contact sensors, electrical resistance change during compression was measured and found to increase by 4 times in the parallel versus vertical direction. Observation and results of the buckling region nature and relationship with applied strain and contacting substrates are important for applying the nanotube arrays to energy absorbing cushions, tunable dampers, thermal contacts, contact sensing, chemical sensing, or in sliding contact.

  19. Pipe-Wire TiO2-Sn@Carbon Nanofibers Paper Anodes for Lithium and Sodium Ion Batteries.

    Science.gov (United States)

    Mao, Minglei; Yan, Feilong; Cui, Chunyu; Ma, Jianmin; Zhang, Ming; Wang, Taihong; Wang, Chunsheng

    2017-06-14

    Metallic tin has been considered as one of the most promising anode materials both for lithium (LIBs) and sodium ion battery (NIBs) because of a high theoretical capacity and an appropriate low discharge potential. However, Sn anodes suffer from a rapid capacity fading during cycling due to pulverization induced by severe volume changes. Here we innovatively synthesized pipe-wire TiO 2 -Sn@carbon nanofibers (TiO 2 -Sn@CNFs) via electrospinning and atomic layer deposition to suppress pulverization-induced capacity decay. In pipe-wire TiO 2 -Sn@CNFs paper, nano-Sn is uniformly dispersed in carbon nanofibers, which not only act as a buffer material to prevent pulverization, but also serve as a conductive matrix. In addition, TiO 2 pipe as the protection shell outside of Sn@carbon nanofibers can restrain the volume variation to prevent Sn from aggregation and pulverization during cycling, thus increasing the Coulombic efficiency. The pipe-wire TiO 2 -Sn@CNFs show excellent electrochemical performance as anodes for both LIBs and NIBs. It exhibits a high and stable capacity of 643 mA h/g at 200 mA/g after 1100 cycles in LIBs and 413 mA h/g at 100 mA/g after 400 cycles in NIBs. These results would shed light on the practical application of Sn-based materials as a high capacity electrode with good cycling stability for next-generation LIBs and NIBs.

  20. 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

  1. Carbon Nanotube and Nanofiber Exposure Assessments: An Analysis of 14 Site Visits

    Science.gov (United States)

    Dahm, Matthew M.; Schubauer-Berigan, Mary K.; Evans, Douglas E.; Birch, M. Eileen; Fernback, Joseph E.; Deddens, James A.

    2015-01-01

    Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 µg m−3 as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 µg m−3 with a geometric mean (GM) of 0.34 µg m−3 and an 8-h TWA of 0.16 µg m−3. PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 µg m−3 with a GM of 1.21 µg m−3. PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm3 with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2–5 µm range as well as agglomerates >5 µm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman ρ = 0.39, P 1 μg m−3. Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF

  2. Asymmetric supercapacitors based on functional electrospun carbon nanofiber/manganese oxide electrodes with high power density and energy density

    Science.gov (United States)

    Lin, Sheng-Chi; Lu, Yi-Ting; Chien, Yu-An; Wang, Jeng-An; You, Ting-Hsuan; Wang, Yu-Sheng; Lin, Chih-Wen; Ma, Chen-Chi M.; Hu, Chi-Chang

    2017-09-01

    Carbon nanofibers modified with carboxyl groups (CNF-COOH) possessing good wettability and high porosity are homogeneously deposited with amorphous manganese dioxide (amorphous MnO2) by potentiodynamic deposition for asymmetric super-capacitors (ASCs). The potential-cycling in 1 M H2SO4 successfully enhances the hydrophilicity of carbonized polymer nanofibers and facilitates the access of electrolytes within the CNF-COOH matrix. This modification favors the deposition of amorphous MnO2 and improves its electrochemical utilization. In this composite, MnO2 homogeneously dispersed onto CNF-COOH provides desirable pseudocapacitance and the CNF-COOH network works as the electron conductor. The composite of CNF-COOH@MnO2-20 shows a high specific capacitance of 415 F g-1 at 5 mV s-1. The capacitance retention of this composite is 94% in a 10,000-cycle test. An ASC cell consisting of this composite and activated carbon as positive and negative electrodes can be reversibly charged/discharged to a cell voltage of 2.0 V in 1 M Na2SO4 and 4 mM NaHCO3 with specific energy and power of 36.7 Wh kg-1 and 354.9 W kg-1, respectively. This ASC also shows excellent cell capacitance retention (8% decay) in the 2V, 10,000-cycle stability test, revealing superior performance.

  3. Using Electrospinning-Based Carbon Nanofiber Webs for Methanol Crossover Control in Passive Direct Methanol Fuel Cells

    Science.gov (United States)

    Fang, Guoyun; Chen, Yonghui; Tang, Yong

    2018-01-01

    Methanol crossover (MCO) significantly affects the performance of a direct methanol fuel cell (DMFC). In order to reduce its effect, this study presents in-house carbon nanofiber webs (CNWs) used as a porous methanol barrier for MCO control in a passive DMFC. The CNW is made from polyacrylonitrile (PAN) by using electrospinning and heat treatment. The impacts of PAN concentration and carbonizing temperature on the material properties are considered. The concentration of PAN has a great effect on the micro structures of the CNWs since a higher concentration of PAN leads to a larger nanofiber diameter and lower porosity. A higher carbonizing temperature helps promote the sample conductivity. The use of CNWs has twofold effects on the cell performance. It helps significantly enhance the cell performance, especially at a low methanol concentration due to its balanced effect on reactant and product management. There is an increase in peak power density of up to 53.54% when the CNW is used, in contrast with the conventional DMFC at 2 mol/L. The dynamic and constant-load performances of the fuel cell based on CNWs are also investigated in this work. PMID:29300368

  4. Carbon nanofiber-filled conductive silicone elastomers as soft, dry bioelectronic interfaces.

    Science.gov (United States)

    Slipher, Geoffrey A; Hairston, W David; Bradford, J Cortney; Bain, Erich D; Mrozek, Randy A

    2018-01-01

    Soft and pliable conductive polymer composites hold promise for application as bioelectronic interfaces such as for electroencephalography (EEG). In clinical, laboratory, and real-world EEG there is a desire for dry, soft, and comfortable interfaces to the scalp that are capable of relaying the μV-level scalp potentials to signal processing electronics. A key challenge is that most material approaches are sensitive to deformation-induced shifts in electrical impedance associated with decreased signal-to-noise ratio. This is a particular concern in real-world environments where human motion is present. The entire set of brain information outside of tightly controlled laboratory or clinical settings are currently unobtainable due to this challenge. Here we explore the performance of an elastomeric material solution purposefully designed for dry, soft, comfortable scalp contact electrodes for EEG that is specifically targeted to have flat electrical impedance response to deformation to enable utilization in real world environments. A conductive carbon nanofiber filled polydimethylsiloxane (CNF-PDMS) elastomer was evaluated at three fill ratios (3, 4 and 7 volume percent). Electromechanical testing data is presented showing the influence of large compressive deformations on electrical impedance as well as the impact of filler loading on the elastomer stiffness. To evaluate usability for EEG, pre-recorded human EEG signals were replayed through the contact electrodes subjected to quasi-static compressive strains between zero and 35%. These tests show that conductive filler ratios well above the electrical percolation threshold are desirable in order to maximize signal-to-noise ratio and signal correlation with an ideal baseline. Increasing fill ratios yield increasingly flat electrical impedance response to large applied compressive deformations with a trade in increased material stiffness, and with nominal electrical impedance tunable over greater than 4 orders of

  5. Carbon nanofiber-filled conductive silicone elastomers as soft, dry bioelectronic interfaces.

    Directory of Open Access Journals (Sweden)

    Geoffrey A Slipher

    Full Text Available Soft and pliable conductive polymer composites hold promise for application as bioelectronic interfaces such as for electroencephalography (EEG. In clinical, laboratory, and real-world EEG there is a desire for dry, soft, and comfortable interfaces to the scalp that are capable of relaying the μV-level scalp potentials to signal processing electronics. A key challenge is that most material approaches are sensitive to deformation-induced shifts in electrical impedance associated with decreased signal-to-noise ratio. This is a particular concern in real-world environments where human motion is present. The entire set of brain information outside of tightly controlled laboratory or clinical settings are currently unobtainable due to this challenge. Here we explore the performance of an elastomeric material solution purposefully designed for dry, soft, comfortable scalp contact electrodes for EEG that is specifically targeted to have flat electrical impedance response to deformation to enable utilization in real world environments. A conductive carbon nanofiber filled polydimethylsiloxane (CNF-PDMS elastomer was evaluated at three fill ratios (3, 4 and 7 volume percent. Electromechanical testing data is presented showing the influence of large compressive deformations on electrical impedance as well as the impact of filler loading on the elastomer stiffness. To evaluate usability for EEG, pre-recorded human EEG signals were replayed through the contact electrodes subjected to quasi-static compressive strains between zero and 35%. These tests show that conductive filler ratios well above the electrical percolation threshold are desirable in order to maximize signal-to-noise ratio and signal correlation with an ideal baseline. Increasing fill ratios yield increasingly flat electrical impedance response to large applied compressive deformations with a trade in increased material stiffness, and with nominal electrical impedance tunable over greater

  6. Graphene oxide/oxidized carbon nanofiber/mineralized hydroxyapatite based hybrid composite for biomedical applications

    Science.gov (United States)

    Murugan, N.; Sundaramurthy, Anandhakumar; Chen, Shen-Ming; Sundramoorthy, Ashok K.

    2017-12-01

    Hydroxyapatite (Ca10(PO4)6(OH)2, HAP), a multi-mineral substituted calcium phosphate is the main mineral component of tooth enamel and bone, has become an important biomaterial for biomedical applications. However, as-synthesized HAP has poor mechanical properties and inferior wear resistance, so it is not suitable to use in bone tissue engineering applications. We report the successful incorporation of oxidized carbon nanofibers (O-CNF) and graphene oxide (GO) into the mineralized hydroxyapatite (M-HAP) which showed excellent mechanical and biological properties. GO improved the high mechanical strength and corrosion protection of the substrate in simulated body fluid (SBF) solution and promoted the viability of osteoblasts MG63 cells. As-prepared M-HAP/O-CNF/GO composite showed materials characteristics that similar to natural bone (M-HAP) with high mechanical strength. The resultant M-HAP/O-CNF/GO composite was characterized out by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and Fourier-transform infrared spectroscopy (FT-IR), respectively. The mechanical strength of the material was determined by Vicker’s micro-hardness method and it was found that M-HAP/O-CNF/GO (468  ±  4 Hv) composite has superior mechanical properties than M-HAP (330  ±  3 Hv) and M-HAP/GO (425  ±  5 Hv) samples. In addition, antibacterial activity of the composite was studied against Staphylococcus aureus and Escherichia coli. Furthermore, the cell viability of the composite was observed in vitro against osteoblast cells. All these studies confirmed that the M-HAP/O-CNF/GO composite can be considered as potential candidate for dental and orthopedic applications.

  7. 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.

  8. Origin of the Excellent Performance of Ru on Nitrogen-Doped Carbon Nanofibers for CO2Hydrogenation to CH4.

    Science.gov (United States)

    Roldán, Laura; Marco, Yanila; García-Bordejé, Enrique

    2017-03-22

    Carbon materials have rarely been used as support for CO 2 methanation, which is usually carried out using catalysts supported on metal oxides. Here, it is shown that Ru nanoparticles supported on nitrogen-doped carbon nanofibers (NCNF) provide competitive CH 4 production rate and stability compared to Al 2 O 3 -supported catalysts. Contrary to the general belief about the inert nature of carbon supports, it is demonstrated that NCNF is a non-innocent spectator in CO 2 methanation due to its ability to store a high amount of CO ad reaction intermediates. This explains the excellent catalytic behaviour afforded by this unconventional catalyst support. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Biotechnology humic acids-based electrospun carbon nanofibers as cost-efficient electrodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhao, Pin-Yi; Guo, Yan; Yu, Bao-Jun; Zhang, Jie; Wang, Cheng-Yang

    2016-01-01

    Bio-based, cost-effective carbon nanofibers are fabricated from polyacrylonitrile (PAN) – refined biotechnology humic acids (RB) via simple eletrospinning after stabilization and carbonization. The influence of PAN/RB mass ratios and heat-treatment temperatures (HTTs) on structure and morphology is systematically studied. Excitingly, a first discharge/charge capacity of 937.9/613.4 mAh g −1 (coulombic efficiency of 65.4%) is achieved at 20 mA g −1 for PB7/3-800 in lithium-ion batteries (LIBs). Meanwhile, a charge capacity of 348.2 mAh g −1 (about 89% retention ratio) remains even after 100 cycles at 0.1 A g −1 . It is demonstrated that biomass humic acids can be applied as a promising precursor to fabricate high performance, low-cost, as well as “green” carbon electrode material for LIBs.

  10. 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.

  11. Dye-sensitized solar cells based on anatase TiO2/multi-walled carbon nanotubes composite nanofibers photoanode

    International Nuclear Information System (INIS)

    Du, Pingfan; Song, Lixin; Xiong, Jie; Li, Ni; Wang, Lijun; Xi, Zhenqiang; Wang, Naiyan; Gao, Linhui; Zhu, Hongliang

    2013-01-01

    Highlights: ► TiO 2 /multi-walled carbon nanotubes (MWCNTs) hybrid nanofibers are prepared via electrospinning. ► Dye-sensitized solar cells (DSSCs) are assembled using TiO 2 /MWCNTs nanofibers film as photoanode. ► Energy conversion efficiency of DSSCs is greatly dependent on the content of MWCNTs. ► Moderate MWCNTs incorporation can substantially enhance the performance of DSSCs. - Abstract: Anatase TiO 2 /multi-walled carbon nanotubes (TiO 2 /MWCNTs) hybrid nanofibers (NFs) film was prepared via a facile electrospinning method. Dye-sensitized solar cells (DSSCs) based on TiO 2 /MWCNTs composite NFs photoanodes with different contents of MWCNTs (0, 0.1, 0.3, 0.5, 1 wt.%) were assembled using N719 dye as sensitizer. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Raman spectrometer were used to characterize the TiO 2 /MWCNTs electrode films. The photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate the photoelectric properties of the DSSCs. The results reveal that the energy conversion efficiency is greatly dependent on the content of MWCNTs in the composite NFs film, and a moderate incorporation of MWCNTs can substantially enhance the performance of DSSCs. When the electrode contains 0.3 wt.% MWCNTs, the corresponding solar cell yield the highest efficiency of 5.63%. This efficiency value is approximately 26% larger than that of the unmodified counterpart.

  12. 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.

  13. 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.

  14. Facile electrospinning preparation of phosphorus and nitrogen dual-doped cobalt-based carbon nanofibers as bifunctional electrocatalyst

    Science.gov (United States)

    Wang, Zhuang; Zuo, Pengjian; Fan, Liquan; Han, Jianan; Xiong, Yueping; Yin, Geping

    2016-04-01

    A novel electrochemical catalyst of phosphorus and nitrogen dual-doped cobalt-based carbon nanofibers (Cosbnd Nsbnd P-CNFs) is prepared by a facile and cost-effective electrospinning technique. Excellent features of the porous carbon nanofibers with large amounts of Co atoms, N/P-doping effect, abundant pyridinic-N and Cosbnd Nx clusters as catalytic active sites, and the advantages of the structure and composition result in a high catalytic efficiency. In alkaline or acidic media, Cosbnd Nsbnd P-CNFs exhibits remarkable electrocatalytic activities and kinetics for oxygen reduction reaction (ORR), superior methanol tolerance and stability, and a similar four-electron pathway. In addition, Cosbnd Nsbnd P-CNFs also shows excellent performance for hydrogen evolution reaction (HER), offering a low onset potential of -0.216 V and a stable current density of 10 mA cm-2 at potential of -0.248 V. The mechanism of ORR and HER catalytic active site arises from the doping of N/P atoms in the Co-based CNFs, which is responsible for the excellent electrocatalytic performance. Due to the excellent catalytic efficiencies, Cosbnd Nsbnd P-CNFs act as a promising catalyst material for fuel cells and water splitting technologies.

  15. Aligned poly(ε-caprolactone)/graphene oxide and reduced graphene oxide nanocomposite nanofibers: Morphological, mechanical and structural properties.

    Science.gov (United States)

    Ramazani, Soghra; Karimi, Mohammad

    2015-11-01

    A number of studies have demonstrated that the mechanical properties of electrospun polymeric nanofibrous scaffolds are enhanced with the incorporation of graphene and its derivatives, thus developing their applications in hard tissue engineering. However, our understanding of the relationship between the microstructure and properties of these fibrous scaffolds and how they are influenced by graphene oxide (GO) and reduced graphene oxide (RGO) loading is much more limited. Thus, in this paper, poly(ε-caprolactone) (PCL)/GO and RGO nanocomposite nanofibers containing 0, 0.1, 0.5 and 1wt.% GO and RGO were prepared using an electrospinning technique. With the addition of 0.1wt.% of GO and RGO nanosheets in PCL, the tensile strength of PCL scaffolds increased over ~160 and 304% respectively and elastic modulus increased over 103 and 163% due to the good dispersion of the nanosheets and their interaction with the molecular chains of PCL. These were supported by the parallel increase in relaxation time and molecular orientation of PCL chains at the presence of nanosheets with a loading of 0.1wt.%. The enhancement effect of the nanosheets was weakened with an increase in GO and RGO loading up to 1wt.% in which it is connected to a partial exfoliation of the nanosheets. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

    International Nuclear Information System (INIS)

    Marquez, F.; Morant, C.; Elizalde, E.; Roque-Malherbe, R.; Lopez, V.; Zamora, F.; Domingo, C.

    2010-01-01

    Arrays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 degree C. The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.

  17. Single layers of WS2 nanoplates embedded in nitrogen-doped carbon nanofibers as anode materials for lithium-ion batteries

    Science.gov (United States)

    Yu, Sunmoon; Jung, Ji-Won; Kim, Il-Doo

    2015-07-01

    Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances.Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances. Electronic supplementary information (ESI) available: Experimental section, SEM images of WS2 powder and ground WS2 powder, TEM image and SAED pattern of the WS2 powder, Raman spectra of the WS2 powder, CV curves of the WS2 powder, voltage profiles of the WS2 powder, schematic diagram of WS2@NCNFs undergoing lithium storage reactions, electrochemical performance of NCNFs, morphologies and EDS mapping of WS2@NCNFs after cycling, and a table of contributions of NCNFs to the specific capacity. See DOI: 10.1039/c5nr02425k

  18. The effect of tin content to the morphology of Sn/carbon nanofiber and the electrochemical performance as anode material for lithium batteries

    International Nuclear Information System (INIS)

    Wang Haiying; Gao Po; Lu Saifeng; Liu Haidong; Yang Gang; Pinto, João; Jiang Xuefan

    2011-01-01

    By using electrospinning and carbonization, tin nanoparticles enwrapped in carbon nano-fibers (Sn/C) present high capacity and well cyclic performance. The precursor compositions of SnCl 2 and polyacrylonitrile (SnCl 2 /PAN) have a significant effect on the crystal structure, morphology of Sn/C composites, and the electrochemical performance. Along with the increased concentration of tin in the precursors of SnCl 2 /PAN, the diameters of the carbonized Sn/C nanofibers are decreased. The samples of SnCl 2 /PAN with starting weight ratio 3:2 (Sn3Pan2), 1:1 (Sn1Pan1) and 2:3 (Sn2Pan3) present the initial discharge capacity 977.8, 1329.8, and 1137.0 mAh g −1 , respectively. In the following cycles, the Sn/C nanofibers present high capacity and well cyclic performance. The sample Sn1Pan1 retains a charge capacity of 741.1 mAh g −1 (92% of the initial charge capacity) after 40 cycles. Because the nanoparticles of tin metal are enwrapped in carbon nanofibers, the volume change and aggregation of metal anode are decreased during charging and discharging processes.

  19. Synergetic interface between NiO/Ni3S2 nanosheets and carbon nanofiber as binder-free anode for highly reversible lithium storage

    Science.gov (United States)

    Jiang, Jialin; Ma, Chao; Yang, Yinbo; Ding, Jingjing; Ji, Hongmei; Shi, Shaojun; Yang, Gang

    2018-05-01

    A novel heterostructure of NiO/Ni3S2 nanoflake is synthesized and composited with carbon nanofibers (CNF) membrane. NiO/Ni3S2 nanoflakes are homogeneously dispersed in CNF network, herein, NiO/Ni3S2 like leaf and CNF like branch. Carbon nanofibers network efficiently prevents the pulverization and buffers the volume changes of NiO/Ni3S2, meanwhile, NiO/Ni3S2 nanoflakes through the conductive channels of carbon nanofibers own improved Li+ diffusion ability and structural stability. The capacity of NiO/Ni3S2/CNF reaches to 519.2 mA g-1 after 200 cycles at the current density of 0.5 A g-1 while NiO/Ni3S2 fades to 71 mAh g-1 after 40 cycles. Owing to the synergetic structure, the resultant binder-free electrode NiO/Ni3S2/carbon nanofibers shows an excellent reversible lithium storage capability.

  20. Preparation of mesohollow and microporous carbon nanofiber and its application in cathode material for lithium–sulfur batteries

    International Nuclear Information System (INIS)

    Wu, Yuanhe; Gao, Mingxia; Li, Xiang; Liu, Yongfeng; Pan, Hongge

    2014-01-01

    Highlights: • Mesohollow and microporous carbon fibers were prepared via electrospinning and carbonization. • Sulfur (S) incorporated into the porous fibers by thermal heating in 60 wt.%, forming composite. • S fills fully in the micropores and partially in the mesohollows of the carbon fibers. • The composite shows high capacity and capacity retention as cathode material for Li–S batteries. • Mesohollow and microporous structure is effective in improving the property of S cathode. - Abstract: Mesohollow and microporous carbon nanofibers (MhMpCFs) were prepared by a coaxial electrospinning with polyacrylonitrile (PAN) and polymethylmethacrylate (PMMA) as outer and inner spinning solutions followed by a carbonization. The carbon fibers were thermal treated with sublimed sulfur to form S/MhMpCFs composite, which was used as cathode material for lithium–sulfur batteries. Electrochemical study shows that the S/MhMpCFs cathode material provides a maximum capacity of 815 mA h/g after several cycles of activation, and the capacity retains 715 mA h/g after 70 cycles, corresponding to a retention of 88%. The electrochemical property of the S/MhMpCFs composite is much superior than the S-incorporated solid carbon fibers prepared from electrospinning of single PAN. The mechanism of the enhanced electrochemical property of the S/MhMpCFs composite is discussed

  1. 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.

  2. Direct synthesis of mesostructured carbon nanofibers decorated with silver-nanoparticles as a multifunctional membrane for water treatment

    International Nuclear Information System (INIS)

    Taha, Ahmed Aboueloyoun

    2015-01-01

    One-dimensional (1D) porous carbon nanofibers (CNFs) decorated by silver (Ag) nanoparticles (NPs) were prepared using a one-pot/self-template synthesis strategy by combining electrospinning and carbonization methods. The characterization results revealed that AgNPs were homogenously distributed along the CNFs and possessed a relatively uniform nano-size of about 12 nm. The novel membrane distinctively displayed enhanced photocatalytic activity under visible-light irradiation. The membrane exhibited excellent dye degradation and bacteria disinfection in batch experiments. The high photocatalytic activity can be attributed to the highly accessible surface areas, good light absorption capability, and high separation efficiency of photogenerated electron–hole pairs. The as-prepared membranes can be easily recycled because of their 1D property. (paper)

  3. 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.

  4. Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

    National Research Council Canada - National Science Library

    Lee, Haiwon

    2007-01-01

    This project focused on the behavior of single-wall carbon nanotubes (SWCNTs) in the electrophoresis cells and aligned growth of SWCNTs by thermal chemical vapor deposition on selectively deposited metallic nanoparticle...

  5. The growth of aligned carbon nanotubes on quartz substrate by spray pyrolysis of hexane

    International Nuclear Information System (INIS)

    Sadeghian, Zahra

    2008-01-01

    Vertically aligned multiwall carbon nanotubes were grown by spray pyrolysis of hexane as the carbon source in the presence of ferrocene as catalyst precursor on a quartz substrate. In recent work we used optimal experimental parameters for the feeding method, reactor conditions, reaction temperature and time, concentration of catalyst and flow rate of feed and gas. The process parameters were chosen so as to obtain multiwall carbon nanotubes and aligned multiwall carbon nanotubes. The tubes are around 15-80 nm in diameter. The morphology and structure of the samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses

  6. The growth of aligned carbon nanotubes on quartz substrate by spray pyrolysis of hexane

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghian, Zahra [Department of Gas, Research Institute of Petroleum Industry (RIPI), PO Box 14857-3311, West Boulevard Azadi Sport Complex, Tehran (Iran, Islamic Republic of)], E-mail: sadeghianz@ripi.ir

    2008-06-18

    Vertically aligned multiwall carbon nanotubes were grown by spray pyrolysis of hexane as the carbon source in the presence of ferrocene as catalyst precursor on a quartz substrate. In recent work we used optimal experimental parameters for the feeding method, reactor conditions, reaction temperature and time, concentration of catalyst and flow rate of feed and gas. The process parameters were chosen so as to obtain multiwall carbon nanotubes and aligned multiwall carbon nanotubes. The tubes are around 15-80 nm in diameter. The morphology and structure of the samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses.

  7. Graphene oxide-supported carbon nanofiber-like network derived from polyaniline: A novel composite for enhanced glucose oxidase bioelectrode performance.

    Science.gov (United States)

    Kang, Zepeng; Jiao, Kailong; Xu, Xinping; Peng, Ruiyun; Jiao, Shuqiang; Hu, Zongqian

    2017-10-15

    A three-dimensional architecture of PANI@GO hybrid was synthesized via in-situ polymerization of aniline monomers on the surface of graphene oxide (GO) and carbonized at 1600°C. The SEM images showed that surfaces of planar GO were covered by a compact nanofiber-like polyaniline (PANI) layer which presented an interconnected network. Nanofiber-like PANI on the GO surface was mostly preserved and became the carbon nanofibers (CNFs) after carbonization. The TEM images showed that the carbonized PANI grew seamlessly on the GO surface and served as conductive "network" between interlayers of GO. The carbonized PANI@GO hybrid was used to modify a glassy carbon electrode (GCE) based on GOx, resulting in efficient direct electron transfer (DET) and excellent bio-catalytic performance. In addition, a glucose/O 2 fuel cell constructed using Nafion/GOx/PANI 1600 @GO/GCE as the anode and an E-TEK Pt/C modified GCE as the cathode generated a maximum power density of 0.756mWcm -2 at 0.42V. Findings in this study may be helpful for exploiting novel materials for immobilization of enzymes through carbonizing conducting polymers or their composites with inorganic materials at high temperature for applications in enzymatic biofuel cells or biosensors. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Nondestructive sensing and stress transferring evaluation of carbon nanotube, nanofiber, and Ni nanowire strands/polymer composites using an electro-micromechanical technique

    Science.gov (United States)

    Park, Joung-Man; Kim, Sung-Ju; Jung, Jin-Gyu; Hansen, George; Yoon, Dong-Jin

    2006-03-01

    Nondestructive damage sensing and load transfer mechanisms of carbon nanotube (CNT), nanofiber (CNF), and Ni nanowire strands/epoxy composites were investigated using electro-micromechanical technique. Electrospun PVDF nanofiber was also prepared as a piezoelectric sensor. High volume% CNT/epoxy composites showed significantly higher tensile properties than neat and low volume% CNT/epoxy composites. CNF /epoxy composites with smaller aspect ratio showed higher apparent modulus due to high volume content in case of shorter aspect ratio. Using Ni nanowire strands/silicone composites with different content, load sensing response of electrical contact resistivity was investigated under tensile and compression condition. The mechanical properties of Ni nanowire strands with different type and content/epoxy composites were indirectly measured apparent modulus using uniformed cyclic loading and electro-pullout test. CNT or Ni nanowire strands/epoxy composites showed humidity and temperature sensing within limited ranges, 20 vol% reinforcement. Thermal treated electrospun PVDF nanofiber showed higher mechanical properties than the untreated case due to increased crystallization, whereas load sensing decreased in heat treated case. Electrospun PVDF nanofiber web also responded the sensing effect on humidity and temperature. Nanocomposites using CNT, CNF, Ni nanowire strands, and electrospun PVDF nanofiber web can be applicable practically for multifunctional applications nondestructively.

  9. Purification and alignment of arc-synthesis single-walled carbon nanotube bundles

    Science.gov (United States)

    Huang, Houjin; Kajiura, Hisashi; Yamada, Atsuo; Ata, Masafumi

    2002-04-01

    We report here a scalable method for purification and alignment of single-walled carbon nanotubes (SWNT) in an aqueous solution. Arc-synthesis soot containing SWNTs is first treated with a concentrated nitric acid. After removal of most of the impurities and water, macroscopic and well-aligned SWNT bundles up to several centimeters long are formed in a rotary evaporator. Alignment of the SWNT bundles is ascribed to the liquid flow induced by rotary evaporation and van der Waals interactions among the bundles. The aligned SWNT bundles are further purified by ultrasonic Soxhlet extraction and annealing.

  10. Heating-Enhanced Dielectrophoresis for Aligned Single-Walled Carbon Nanotube Film of Ultrahigh Density.

    Science.gov (United States)

    Gu, Qingyuan; Guezo, Maud; Folliot, Hervé; Batte, Thomas; Loualiche, Slimane; Stervinou, Julie

    2017-12-01

    In this paper, we demonstrate that the alignment density of individualized single-walled carbon nanotubes (SWCNTs) can be greatly improved by heating-enhanced dielectrophoresis (HE-DEP) process. The observations by scanning electron microscope (SEM) suggest ultrahigh alignment density and good alignment quality of SWCNTs. The intuitive alignment density of individualized SWCNTs is much higher than the currently reported best results. The reason of this HE-DEP process is explained by simulation work and ascribed to the heating-enhanced convection process, and the "convection force" induced by the heating effect is assessed in a novel way.

  11. High rate capability and cyclic stability of hierarchically porous Tin oxide (IV)-carbon nanofibers as anode in lithium ion batteries

    Science.gov (United States)

    Gupta, Ashish; Dhakate, Sanjay R.; Gurunathan, P.; Ramesha, K.

    2017-10-01

    Tin oxide-carbon composite porous nanofibres exhibiting superior electrochemical performance as lithium ion battery (LIB) anode have been prepared using electrospinning technique. Surface morphology and structural characterizations of the composite material is carried out by techniques such as XRD, FESEM, HR-TEM, XPS, TGA and Raman spectroscopy. FESEM and TEM studies reveal that nanofibers have a uniform diameter of 150-180 nm and contain highly porous outer wall. The carbon content is limited to 10% in the nanofibers as shown by the TGA and EDAX which does not fade the high capacity of SnO2. These nanofibers delivered a higher discharge capacity of 722 mAh/g even after 100 cycles at high rate of 1C. The excellent electrochemical performance can be ascribed to the synergy effect of small amount of carbon in the composite and the hierarchically porous structure which accommodate large volume changes associated with Li-ion insertion-desertion. The porous nano-architecture would also provide a short diffusion path for Li+ ions in addition to facilitating high flux of electrolyte percolation through micropores. The electrochemical performance of composite material has also been tested at 60 °C at a higher rate of 2C and 5C. Post cycling FESEM analysis shows no volumetric and morphology changes in porous nanofibers after completing rate capability at high rate of 10C.

  12. The Chemical Deposition Method for the Decoration of Palladium Particles on Carbon Nanofibers with Rapid Conductivity Changes

    Directory of Open Access Journals (Sweden)

    Hoik Lee

    2016-11-01

    Full Text Available Palladium (Pd metal is well-known for hydrogen sensing material due to its high sensitivity and selectivity toward hydrogen, and is able to detect hydrogen at near room temperature. In this work, palladium-doped carbon nanofibers (Pd/CNFs were successfully produced in a facile manner via electrospinning. Well-organized and uniformly distributed Pd was observed in microscopic images of the resultant nanofibers. Hydrogen causes an increment in the volume of Pd due to the ability of hydrogen atoms to occupy the octahedral interstitial positions within its face centered cubic lattice structure, resulting in the resistance transition of Pd/CNFs. The resistance variation was around 400%, and it responded rapidly within 1 min, even in 5% hydrogen atmosphere conditions at room temperature. This fibrous hybrid material platform will open a new and practical route and stimulate further researches on the development of hydrogen sensing materials with rapid response, even to low concentrations of hydrogen in an atmosphere.

  13. Photocatalysis of sub-ppm limonene over multiwalled carbon nanotubes/titania composite nanofiber under visible-light irradiation.

    Science.gov (United States)

    Jo, Wan-Kuen; Kang, Hyun-Jung

    2015-01-01

    This study was conducted under visible-light exposure to investigate the photocatalytic characteristics of a multiwalled carbon nanotube/titania (TiO2) 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 TiO2 nanofibers or P25 TiO2, 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 TiO2. 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 78.0s, 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 TiO2. Other provisional gas-phase intermediates included cyclopropyl methyl ketone and 2-ethylbutanal. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Carbon nanotubes functionalized electrospun nanofibers formed 3D electrode enables highly strong ECL of peroxydisulfate and its application in immunoassay.

    Science.gov (United States)

    Dai, Hong; Xu, Guifang; Zhang, Shupei; Gong, Lingshan; Li, Xiuhua; Yang, Caiping; Lin, Yanyu; Chen, Jinghua; Chen, Guonan

    2014-11-15

    A new biosensing platform based on electrospun carbon nanotubes nanofibers (CNTs@PNFs) composite, which enabled strong electrochemiluminescent emission of peroxydisulfate, was firstly developed for immunoassay with favorable analytical performances, and then was utilized to evaluate the interaction between antibody and antigen in vitro. Moreover, the obvious ECL image of peroxydisulfate on the prepared sensing platform was firstly recorded in this report. In order to expand the application of peroxydisulfate ECL, the specific recognization biomolecules, α-fetoprotein (AFP) antibody was bound to the functionalized film via electrostatic interaction for fabricating label-free ECL immunosensor to detect α-AFP. Based on the ECL change resulting from the specific immunoreaction between antigen and antibody, the quantitative analysis for AFP with wide dynamic response in the range from 0.1 pg mL(-1) to 160 ng mL(-1) was realized. And the limit of detection was estimated to be 0.09 pg mL(-1). Therefore, the flexible sensing platform not only acted as the sensitized sensing element, but also offered a suitable carrier for immobilization of biological recognition elements with low-toxicity and eco-friendliness, which opened a promising approach to developing further electrospun nanofiber based amplified ECL biosensor with favorable analytical performances. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Aligned Carbon Nano tubes Array by DC Glow Plasma Etching for Super capacitor

    International Nuclear Information System (INIS)

    Luo, Y.; Li, X.; Gong, Z.; Sheng, Z.; Peng, X.; Mou, Q.; He, M.; Li, X.; Chen, H.; Luo, Y.; Li, X.; Li, X.

    2013-01-01

    To open the end of carbon nano tubes and make these ends connect with functional carboxyl group, aligned carbon nano tubes (CNTs) arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nano tubes array as electrode materials to build super capacitor, we found that the capacity (32.2 F/g) increased significantly than that of pure carbon nano tubes (6.7 F/g)

  16. Electrospun nanofibers for neural tissue engineering

    Science.gov (United States)

    Xie, Jingwei; MacEwan, Matthew R.; Schwartz, Andrea G.; Xia, Younan

    2010-01-01

    Biodegradable nanofibers produced by electrospinning represent a new class of promising scaffolds to support nerve regeneration. We begin with a brief discussion on the electrospinning of nanofibers and methods for controlling the structure, porosity, and alignment of the electrospun nanofibers. The methods include control of the nanoscale morphology and microscale alignment of the nanofibers, as well as the fabrication of macroscale, three-dimensional tubular structures. We then highlight recent studies that utilize electrospun nanofibers to manipulate biological processes relevant to nervous tissue regeneration, including stem cell differentiation, guidance of neurite extension, and peripheral nerve injury treatments. The main objective of this feature article is to provide valuable insights into methods for investigating the mechanisms of neurite growth on novel nanofibrous scaffolds and optimization of the nanofiber scaffolds and conduits for repairing peripheral nerve injuries.

  17. Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

    OpenAIRE

    Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

    2016-01-01

    Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive ...

  18. Physical and Chemical Properties of Pan-Derived Electrospun Activated Carbon Nanofibers and Their Potential for Use As An Adsorbent for Toxic Industrial Chemicals (Postprint)

    Science.gov (United States)

    2012-09-14

    carbon fiber cloth (ACFC) and Calgon BPL™ granular activated carbon (GAC) 2 Methods 2.1 Precursor selection and nonwoven nanofiber material preparation...respirators, re- generative filter systems that can protect against TICs, or perhaps smaller and more energy-efficient pressure-swing- adsorption systems...Peterson, G.W., Karwacki, C.: Novel collective protection filters for emerging TIC requirements: axial- and radial-flow filter de- signs. Edgewood Chemical

  19. Mechanical and electromagnetic interference shielding Properties of poly(vinyl alcohol)/graphene and poly(vinyl alcohol)/multi-walled carbon nanotube composite nanofiber mats and the effect of Cu top-layer coating.

    Science.gov (United States)

    Fujimori, Kazushige; Gopiraman, Mayakrishnan; Kim, Han-Ki; Kim, Byoung-Suhk; Kim, Ick-Soo

    2013-03-01

    We report the mechanical property and electromagnetic interference shielding effectiveness (EMI SE) of poly(vinyl alcohol) (PVA)/graphene and PVA/multi-walled carbon nanotube (MWCNT) composite nanofibers prepared by electrospinning. The metal (Cu) was deposited on the resultant PVA composite nanofibers using metal deposition technique in order to improve the mechanical properties and EMI shielding properties. The resulting PVA composite nanofibers and Cu-deposited corresponding nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Tensile tests were performed on the PVA/graphene and PVA/MWCNT composite nanofibers. The tensile strength of the PVA/graphene and PVA/MWCNT composite nanofibers was found to be 19.2 +/- 0.3 MPa at graphene content - 6.0 wt% and 12.2 +/- 0.2 MPa at MWCNT content - 3.0 wt%, respectively. The EMI SE of the Cu-deposited PVA/graphene composite nanofibers was significantly improved compared to pure PVA/graphene composite nanofibers, and also depended on the thickness of Cu metal layer deposited on the PVA composite nanofibers.

  20. 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.

  1. Electrospun Nanofibers: Solving Global Issues

    Science.gov (United States)

    Si, Yang; Tang, Xiaomin; Yu, Jianyong; Ding, Bin

    Energy and environment will head the list of top global issues facing society for the next 50 years. Nanotechnology is responding to these challenges by designing and fabricating functional nanofibers optimized for energy and environmental applications. The route toward these nano-objects is based primarily on electrospinning: a highly versatile method that allows the fabrication of continuous fibers with diameters down to a few nanometers. The mechanism responsible for the fiber formation mainly includes the Taylor Cone theory and flight-instability theory, which can be predicted theoretically and controlled experimentally. Moreover, the electrospinning has been applied to natural polymers, synthetic polymers, ceramics, and carbon. Fibers with complex architectures, such as ribbon fiber, porous fiber, core-shell fiber, or hollow fiber, can be produced by special electrospinning methods. It is also possible to produce nanofibrous membranes with designed aggregate structure including alignment, patterning, and two-dimensional nanonets. Finally, the brief analysis of nanofibers used for advanced energy and environmental applications in the past decade indicates that their impact has been realized well and is encouraging, and will continually represent a key technology to ensure sustainable energy and preserve our environment for the future.

  2. Synergistic effect of carbon nanofiber and sub-micro filamentary nickel nanostrand on the shape memory polymer nanocomposite

    International Nuclear Information System (INIS)

    Lu, Haibao; Leng, Jinsong; Du, Shanyi; Gou, Jihua

    2011-01-01

    This work studies the synergistic effect of carbon nanofiber (CNF) and sub-micro filamentary nickel nanostrand on the thermal and electrical properties, as well as the electro-active shape memory behavior, of a shape memory polymer (SMP) nanocomposite. The combination of electrical CNF and electromagnetic nickel nanostrand is used to render insulating thermo-responsive SMPs conductive. Subsequently, the shape memory behavior of the SMP can be activated by the electrical resistive heating. It is shown that sub-micro filamentary nickel-coated nanostrands significantly improved the electrical conductivity to facilitate the actuation of the SMP nanocomposite despite the low nanostrand volume content and low electrical voltage. Also the CNFs are blended with the SMP resin to facilitate the dispersion of nanostrands and improve the thermal conductivity to accelerate the electro- and thermo-active responses

  3. 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.

  4. 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.

  5. Remarkable improvement of the wear resistance of poly(vinylidene difluoride) by incorporating polyimide powder and carbon nanofibers

    Science.gov (United States)

    Min, Chunying; Liu, Dengdeng; Shen, Chen; Zhang, Qiaqia; Shen, Xiaojuan; Zhang, Kan

    2017-10-01

    Poly(vinylidene difluoride) (PVDF) composites reinforced via adding different fillers have attracted wide attention in the field of dielectric materials, but few have been reported in the tribological area. In this paper, the effect of polyimide (PI) powder and carbon nanofibers (CF) as reinforcement phases on the friction and wear performance of PVDF composites has been investigated. It was found that PI powder enhances the mechanical and tribological properties of PVDF and especially as the content of the PI powder reaches 5 wt%. In addition, CF and PI exhibited synergistic effect on the tribological properties of PVDF. With PVDF containing 5 wt% PI powder and 20 wt% CF, the friction and wear behavior of the PVDF composite showed the best performance. PVDF, PI powder and CF can form a consistent network structure, which prevents the polymer molecular chains from moving or deformation, decreasing the wear loss of PVDF composites.

  6. Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

    Science.gov (United States)

    Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

    2015-11-01

    Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

  7. Synthesis of Large Arrays of Well-Aligned Carbon Nanotubes on Glass

    Energy Technology Data Exchange (ETDEWEB)

    Bush, P. Siegal, M.P.; Huang, Z.P.; Provencio, P.N.; Ren, Z.F.; Wang, J.H.; Xu, J.W.

    1998-11-10

    Free-standing aligned carbon nanotubes have previously been grown above 7000C on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666oC by plasma-enhanced hot filament chemical vapor deposition. Acetylene (C2H2) gas was used as the carbon source and ammonia (NH3) gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0.1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.

  8. Lignin-derived electrospun carbon nanofiber mats with supercritically deposited Ag nanoparticles for oxygen reduction reaction in alkaline fuel cells

    International Nuclear Information System (INIS)

    Lai, Chuilin; Kolla, Praveen; Zhao, Yong; Fong, Hao; Smirnova, Alevtina L.

    2014-01-01

    Highlights: • Electrospun carbon nanofiber mats were prepared from a natural product of lignin. • The freestanding mats were flexible with BET specific surface area of ∼583 m 2 /g. • The mats were surface-deposited with Ag nanoparticles via the scCO 2 method. • Novel electrocatalytic systems of Ag/ECNFs exhibited high activities towards ORR. - Abstract: Ag nanoparticles (AgNPs) (11, 15, and 25 wt.%) were deposited on the surface of the freestanding and mechanically flexible mats consisting of lignin-derived electrospun carbon nanofibers (ECNFs) by the supercritical CO 2 method followed by the thermal treated at 180 °C. The electrochemical activity of Ag/ECNFs electrocatalyst systems towards oxygen reduction reaction (ORR) was studied in 0.1 M KOH aqueous solution using the rotating disk/rotating ring disk electrode (RDE/RRDE) technique. The SEM, TEM, and XRD results indicated that, the spherical AgNPs were uniformly distributed on the ECNF surface with sizes in the range of 2-10 nm. The electrocatalytic results revealed that, all of the Ag/ECNFs systems exhibited high activity in ORR and demonstrated close-to-theoretical four-electron pathway. In particular, the mass activity of 15 wt.% Ag/ECNFs system was the highest (119 mA mg −1 ), exceeding that of HiSPEC 4100™ commercial Pt/C catalyst (98 mA mg −1 ). This study suggested that the lignin-derived ECNF mats surface-deposited with AgNPs would be promising as cost-effective and highly efficient electrocatalyst for ORR in alkaline fuel cells

  9. Pd-Ni alloy nanoparticle/carbon nanofiber composites: preparation, structure, and superior electrocatalytic properties for sugar analysis.

    Science.gov (United States)

    Guo, Qiaohui; Liu, Dong; Zhang, Xueping; Li, Libo; Hou, Haoqing; Niwa, Osamu; You, Tianyan

    2014-06-17

    Novel Pd-Ni alloy nanoparticle/carbon nanofiber (Pd-Ni/CNF) composites were successfully prepared by a simple method involving electrospinning of precursor polyacrylonitrile/Pd(acac)2/Ni(acac)2 nanofibers, followed by a thermal process to reduce metals and carbonize polyacrylonitrile. The nanostructures of the resulting Pd-Ni/CNF nanocomposites were carefully examined by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). For all the nanocomposites, the Pd-Ni alloy nanoparticles (NPs) were dispersed uniformly and embedded firmly within the framework or on the surface of CNF. The size, composition, and alloy homogeneity of the Pd-Ni alloy NPs could be readily tailored by controlling the feed ratio of metal precursors and the thermal treatment process. Cyclic voltammetric studies showed enhanced redox properties for Pd-Ni/CNF-based electrodes relative to the Ni-metal electrode and significantly improved electrocatalytic activity for sugar (e.g., glucose, fructose, sucrose, and maltose) oxidation. The application potential of Pd-Ni/CNF-based electrodes in flow systems for sugars detection was explored. A very low limit of detection for sugars (e.g., 7-20 nM), high resistance to surface fouling, excellent signal stability and reproducibility, and a very wide detection linear range (e.g., 0.03-800 μM) were revealed for this new type of Pd-Ni/CNF nanocomposite as the detecting electrode. Such detection performances of Pd-Ni/CNF-based electrodes are superior to those of state-of-the-art nonenzymatic sugar detectors that are commercially available or known in the literature.

  10. Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Ian, E-mail: ian.holt@rjah.nhs.uk [Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG (United Kingdom); Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Gestmann, Ingo, E-mail: Ingo.Gestmann@fei.com [FEI Europe B.V., Achtseweg Noord 5, 5651 Eindhoven (Netherlands); Wright, Andrew C., E-mail: a.wright@glyndwr.ac.uk [Advanced Materials Research Laboratory, Glyndwr University, Plas Coch, Mold Rd, Wrexham LL11 2AW (United Kingdom)

    2013-10-15

    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. Highlights: • Highly oriented muscle precursor cells grown on edges of carbon nanotube pads • Mechanical treatment of nanotube pads highly deleterious to cell growth on edges • Larger areas created from wipe-transfer of narrow strips of nanotubes onto elastomer supports • Very high resolution SEM reveals clues to aligned cell growth.

  11. Isolated Hexaphenyl Nanofibers as Optical Waveguides

    DEFF Research Database (Denmark)

    Balzer, F.; Bordo, Vladimir G.; Simonsen, Adam C.

    2003-01-01

    Laser-supported, dipole-assisted self-assembly results in blue-light guiding nanostructures, namely single-crystalline nanofibers of hexaphenyl molecules. The nanofibers are up to 1 mm long, extremely well-aligned to each other and their cross sections can be tuned to span the range from nonguiding...

  12. Electrodeposited binder-free NiCo2O4@carbon nanofiber as a high performance anode for lithium ion batteries

    Science.gov (United States)

    Zhang, Jie; Chu, Ruixia; Chen, Yanli; Jiang, Heng; Zhang, Ying; Huang, Nay Ming; Guo, Hang

    2018-03-01

    Binder-free nickel cobaltite on a carbon nanofiber (NiCo2O4@CNF) anode for lithium ion batteries was prepared via a two-step procedure of electrospinning and electrodeposition. The CNF was obtained by annealing electrospun poly-acrylonitrile (PAN) in nitrogen (N2). The NiCo2O4 nanostructures were then grown on the CNF by electrodeposition, followed by annealing in air. Experimental results showed that vertically aligned NiCo2O4 nanosheets had uniformly grown on the surface of the CNF, forming an interconnected network. The NiCo2O4@CNF possessed considerable lithium storage capacity and cycling stability. It exhibited a high reversible capacity of 778 mAhg-1 after 300 cycles at a current density of 0.25 C (1 C = 890 mAg-1) with an average capacity loss rate of 0.05% per cycle. The NiCo2O4@CNF had considerable rate capacities, delivering a capacity of 350 mAhg-1 at a current density of 2.0 C. The outstanding electrochemical performance can be mainly attributed to the following: (1) The nanoscale structure of NiCo2O4 could not only shorten the diffusion path of lithium ions and electrons but also increase the specific surface area, providing more active sites for electrochemical reactions. (2) The CNF with considerable mechanical strength and electrical conductivity could function as an anchor for the NiCo2O4 nanostructure and ensure an efficient electron transfer. (3) The porous structure resulted in a high specific surface area and an effective buffer for the volume changes during the repeated charge-discharge processes. Compared with a conventional hydrothermal method, electrodeposition could significantly simplify the preparation of NiCo2O4, with a shorter preparation period and lower energy consumption. This work provides an alternative strategy to obtain a high performance anode for lithium ion batteries.

  13. Nitrogen-Doped Carbon Nanofiber/Molybdenum Disulfide Nanocomposites Derived from Bacterial Cellulose for High-Efficiency Electrocatalytic Hydrogen Evolution Reaction.

    Science.gov (United States)

    Lai, Feili; Miao, Yue-E; Huang, Yunpeng; Zhang, Youfang; Liu, Tianxi

    2016-02-17

    To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS2) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS2 nanosheets. The obtained hierarchical pBC-N/MoS2 nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm(-2) at η = 200 mV, low Tafel slope of 61 mV dec(-1), and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS2 nanosheets, the intimate connection between MoS2 nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS2-based nanocomposites as cost-effective HER eletrocatalysts.

  14. Tethering of nicotinamide adenine dinucleotide inside hollow nanofibers for high-yield synthesis of methanol from carbon dioxide catalyzed by coencapsulated multienzymes.

    Science.gov (United States)

    Ji, Xiaoyuan; Su, Zhiguo; Wang, Ping; Ma, Guanghui; Zhang, Songping

    2015-01-01

    Enzymatic conversion of carbon dioxide (CO2) to fuel or chemicals is appealing, but is limited by lack of efficient technology for regeneration and reuse of expensive cofactors. Here we show that cationic polyelectrolyte-doped hollow nanofibers, which can be fabricated via a facile coaxial electrospinning technology, provide an ideal scaffold for assembly of cofactor and multienzymes capable of synthesizing methanol from CO2 through a cascade multistep reaction involving cofactor regeneration. Cofactor and four enzymes including formate, formaldehyde, alcohol, and glutamate dehydrogenases were in situ coencapsulated inside the lumen of hollow nanofibers by involving them in the core-phase solution for coaxial electrospinning, in which cationic polyelectrolyte was predissolved. The polyelectrolyte penetrating across the shell of the hollow nanofibers enabled efficient tethering and retention of cofactor inside the lumen via ion-exchange interactions between oppositely charged polyelectrolytes and cofactor. With carbonic anhydrase assembled on the outer surface of the hollow nanofibers for accelerating hydration of CO2, these five-enzymes-cofactor catalyst system exhibited high activity for methanol synthesis. Compared with methanol yield of only 36.17% using free enzymes and cofactor, the hollow nanofiber-supported system afforded a high value up to 103.2%, the highest reported value so far. It was believed that the linear polyelectrolytes acted as spacers to enhance the shuttling of cofactor between enzymes that were coencapsulated within near vicinity, thus improving the efficiency of the system. The immobilized system showed good stability in reusing. About 80% of its original productivity was retained after 10 reusing cycles, with a cofactor-based cumulative methanol yield reached 940.5%.

  15. Size and Promoter Effects on Stability of Carbon-Nanofiber-Supported Iron-Based Fischer–Tropsch Catalysts

    Science.gov (United States)

    2016-01-01

    The Fischer–Tropsch Synthesis converts synthesis gas from alternative carbon resources, including natural gas, coal, and biomass, to hydrocarbons used as fuels or chemicals. In particular, iron-based catalysts at elevated temperatures favor the selective production of C2–C4 olefins, which are important building blocks for the chemical industry. Bulk iron catalysts (with promoters) were conventionally used, but these deactivate due to either phase transformation or carbon deposition resulting in disintegration of the catalyst particles. For supported iron catalysts, iron particle growth may result in loss of catalytic activity over time. In this work, the effects of promoters and particle size on the stability of supported iron nanoparticles (initial sizes of 3–9 nm) were investigated at industrially relevant conditions (340 °C, 20 bar, H2/CO = 1). Upon addition of sodium and sulfur promoters to iron nanoparticles supported on carbon nanofibers, initial catalytic activities were high, but substantial deactivation was observed over a period of 100 h. In situ Mössbauer spectroscopy revealed that after 20 h time-on-stream, promoted catalysts attained 100% carbidization, whereas for unpromoted catalysts, this was around 25%. In situ carbon deposition studies were carried out using a tapered element oscillating microbalance (TEOM). No carbon laydown was detected for the unpromoted catalysts, whereas for promoted catalysts, carbon deposition occurred mainly over the first 4 h and thus did not play a pivotal role in deactivation over 100 h. Instead, the loss of catalytic activity coincided with the increase in Fe particle size to 20–50 nm, thereby supporting the proposal that the loss of active Fe surface area was the main cause of deactivation. PMID:27330847

  16. Effect of added nickel nitrate on the physical, thermal and morphological characteristics of polyacrylonitrile-based carbon nanofibers

    International Nuclear Information System (INIS)

    Nataraj, S.K.; Kim, B.H.; Yun, J.H.; Lee, D.H.; Aminabhavi, T.M.; Yang, K.S.

    2009-01-01

    Porous carbon nanofibers (CNFs) with enhanced physical, thermal and morphological properties are desirable in many areas like catalyst support in fuel cells and supercapacitors as electrode material. This research addresses the effect of added nickel nitrate in 1, 3 and 5 wt% into polyacrylonitrile (PAN) precursor solution to produce CNF webs using electrospinning method. Based on the quantitative data obtained from field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) images, we can notice that CNFs were formed with diameters in the size range of 100-300 nm after carbonization at 1000 deg. C. Fiber diameter of the random CNFs was decreased by increasing the nickel nitrate contents along with dramatic improvements in porosity and specific surface areas. This study indicated that the optimal nickel nitrate concentration of 5 wt% has produced CNFs with enhanced physical and thermo-chemical properties. The high resolution X-ray diffraction (HR-XRD) showed an increase in intensity of 0 0 2 peak of the CNFs due to the catalytic function of nickel oxide in the carbonized web and these observations are in agreement with the thermal gravimetric data.

  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. Effect of aligned carbon nanotubes on electrical conductivity ...

    Indian Academy of Sciences (India)

    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. Keywords. Carbon nanotube; nanocomposite; electrical effect; magnetic effect. 1. Introduction. To reinforce materials ...

  19. 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.

  20. Enhancement of mechanical and tribotechnical properties of polymer composites with thermoplastic UHMWPE and PEEK matrices by loading carbon nanofibers/nanotubes

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Anh, Nguyen Duc; Alexenko, V. O.; Ivanova, L. R.

    2017-12-01

    For comparative evaluation of the influence of carbon nanofiber/nanotube loading in two different thermoplastic matrices (UHMWPE and PEEK), some mechanical and tribotechnical properties of the nanocomposites have been studied. It is shown that mechanical properties of nanocomposites change in various manners with increasing loading of carbon nanofibers and nanotubes. Herewith, the wear resistance of the "UHMWPE+1 wt% CNF and PEEK + 1 wt% CNF" composites under dry sliding friction is doubled. It is shown that, regardless of various effects on permolecular structure formation, the studied nanofillers enhance the wear resistance of the composites in a similar manner. A comparative analysis of the influence of nanofillers on the modification of mechanical and tribotechnical properties of UHMWPE- and PEEK-based matrices is made.

  1. Synthese et caracterisation de recouvrements organises de nanofibres de carbone par depot chimique en phase vapeur assiste par laser

    Science.gov (United States)

    Longtin, Remi

    The miniaturisation of the transistor that began 50 years ago continues to revolutionise the microelectronics industry by allowing the fabrication of increasingly powerful microprocessors. Unfortunately, the industry is approaching a miniaturisation limit that threatens to slow down its progression unless present day microfabrication techniques are improved or if new nanofabrication techniques are developed. The solution to this challenge not only resides in the nanometre scale patterning of conventional materials such as gold and copper, but also in the synthesis of novel materials. Carbon nanofibers and nanotubes are ideal replacement nanomaterials for microelectronic components such as transistors and both horizontal and vertical interconnects. This is justified by their excellent electrical properties, their nanometre range dimensions and their fiber or tube shape. The goal of this experimental research project is to apply the laser-assisted chemical vapor deposition technique (LCVD) to the synthesis of carbon nanofibers. LCVD utilises a laser beam to initiate and maintain a chemical reaction leading to the deposition of a solid product from the gas phase. More specifically, the goal is to obtain different nanofiber assemblies locally on the surface of a substrate. This thesis focuses primarily on the synthesis of carbon nanofibers. Therefore, its scope includes the synthesis and characterisation of nanofibers as well as a partial process parameter study. Different carbon nanofiber assemblies in the form of non-aligned thin films, vertically aligned nanofiber arrays, horizontally aligned nanofiber mats and carbon-carbon composite coatings were locally synthesized on the surface of an alumina substrate by LCVD. The thin films are 100-200 nm thick and are composed of vermicular nanofibers with a multi-walled internal structure. These nanofibers are 12 to 47 nm in diameter and are several hundred nanometers in length. The vertically aligned nanofibers part of the

  2. Controllable synthesis of Zn{sub 2}TiO{sub 4}-carbon core/shell nanofibers with high photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Peng [Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China); Shao, Changlu, E-mail: clshao@nenu.edu.cn [Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China); Zhang, Mingyi; Guo, Zengcai; Mu, Jingbo; Zhang, Zhenyi; Zhang, Xin; Liang, Pingping; Liu, Yichun [Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China)

    2012-08-30

    Graphical abstract: We describe a controllable route to synthesize Zn{sub 2}TiO{sub 4}-carbon core/shell nanofibers with different thickness of carbon layers (from 2 to 8 nm) as high efficiency photocatalysts. Highlights: Black-Right-Pointing-Pointer Synthesis of Zn{sub 2}TiO{sub 4}-carbon nanofibers with different thickness of carbon layers. Black-Right-Pointing-Pointer Zn{sub 2}TiO{sub 4}-carbon NFs showed photocatalytic activity for the degradation of Rhodamine B. Black-Right-Pointing-Pointer Easy photocatalyst separation and reuse. Black-Right-Pointing-Pointer A general way to fabricate other carbon-coated core/shell photocatalysts. - Abstract: Zn{sub 2}TiO{sub 4}-carbon core/shell nanofibers (Zn{sub 2}TiO{sub 4}-C NFs) with different thickness of carbon layers (from 2 to 8 nm) were fabricated by combining the electrospinning technique and hydrothermal method. The results showed that a uniform carbon layer was formed around the electrospun Zn{sub 2}TiO{sub 4} nanofiber (Zn{sub 2}TiO{sub 4} NFs). By adjusting the hydrothermal fabrication parameters, the thickness of carbon layer varied linearly with the concentration of glucose. Furthermore, the core/shell structure formed between Zn{sub 2}TiO{sub 4} and carbon enhanced the charge separation of pure Zn{sub 2}TiO{sub 4} under ultraviolet excitation, as evidenced by photoluminescence spectra. The photocatalytic studies revealed that the Zn{sub 2}TiO{sub 4}-C NFs exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure Zn{sub 2}TiO{sub 4} NFs under ultraviolet excitation, which might be attributed to the high separation efficiency of photogenerated electrons and holes based on the synergistic effect between carbon and Zn{sub 2}TiO{sub 4}. Notably, the Zn{sub 2}TiO{sub 4}-C NFs could be recycled easily by sedimentation without a decrease of the photocatalytic activity.

  3. Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators

    Science.gov (United States)

    Kaul, Anupama B.; Epp, Larry W.; Bagge, Leif

    2011-01-01

    , lithographically fabricated ap - proaches to form cantilever or bridgetype structures. Top-down approaches, however, rely on complicated and expensive e-beam lithography, and often require a release mechanism. Reso - nance effects in structures synthesized using bottom-up approaches have also recently been reported based on carbon nanotubes, but such approaches have relied on a planar two-dimensional (2D) geometry. In this innovation, vertically aligned tubes synthesized using a bottom- up approach have been considered, where the vertical orientation of the tubes has the potential to increase integration density even further. The simulation of a vertically oriented, cantilevered carbon nanotube was performed using COMSOL Multi - physics, a finite element simulation package. All simulations were performed in a 2D geometry that provided consistent results and minimized computational complexity. The simulations assumed a vertically oriented, cantilevered nanotube of uniform density (1.5 g/cu cm). An elastic modulus was assumed to be 600 GPa, relative permittivity of the nanotube was assumed to be 5.0, and Poisson s ratio was assumed to be 0.2. It should be noted that the relative permittivity and Poisson s ratio for the nanotubes of interest are not known accurately. However, as in previous simulations, the relative permittivity and Poisson s ratios were treated as weak variables in the simulation, and no significant changes were recognized when these variables were varied.

  4. Fabrication of Aligned-Carbon-Nanotube-Composite Paper with High and Anisotropic Conductivity

    Directory of Open Access Journals (Sweden)

    Yuki Fujitsuka

    2012-01-01

    Full Text Available A functional carbon-nanotube (CNT-composite paper is described in which the CNTs are aligned. This “aligned-CNT composite paper” is a flexible composite material that has CNT functionality (e.g., electrical conductivity despite being a paper. An advanced fabrication method was developed to overcome the problem of previous CNT-composite papers, that is, reduced conductivity due to random CNT alignment. Aligning the CNTs by using an alternating current (AC field was hypothesized to increase the electrical conductivity and give the paper an anisotropic characteristic. Experimental results showed that a nonionic surfactant was not suitable as a CNT dispersant for fabricating aligned-CNT composite paper and that catechin with its six-membered rings and hydrophilic groups was suitable. Observation by scanning electron microscopy of samples prepared using catechin showed that the CNTs were aligned in the direction of the AC field on the paper fibers. Measurement of the electric conductivity showed that the surface resistance was different between the direction of the aligned CNTs (high conductivity and that of verticality (low. The conductivity of the aligned-CNT-composite paper samples was higher than that of nonaligned samples. This unique and functional paper, which has high and anisotropic conductivity, is applicable to a conductive material to control the direction of current.

  5. 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.

  6. Electrochemical Performance of Electrospun carbon nanofibers as free-standing and binder-free anodes for Sodium-Ion and Lithium-Ion Batteries

    International Nuclear Information System (INIS)

    Jin, Juan; Shi, Zhi-qiang; Wang, Cheng-yang

    2014-01-01

    Highlights: • Electrospun carbon nanofiber webs were prepared by pyrolysis of polyacrylonitrile. • The webs as binder-free and current collector-free electrodes for SIBs and LIBs. • Different layer spacing and pore size for Li and Na lead different electrochemical behavior. • Electrochemical performances of the electrodes were high. - Abstract: A series of hard carbon nanofiber-based electrodes derived from electrospun polyacrylonitrile (PAN) nanofibers (PAN-CNFs) have been fabricated by stabilization in air at about 280 °C and then carbonization in N 2 at heat treatment temperatures (HTT) between 800 and 1500 °C. The electrochemical performances of the binder-free, current collector-free carbon nanofiber-based anodes in lithium-ion batteries and sodium-ion batteries are systematically investigated and compared. We demonstrate the presence of similar alkali metal insertion mechanisms in both cases, but just the differences of the layer spacing and pore size available for lithium and sodium ion lead the discharge capacity delivered at sloping region and plateau region to vary from the kinds of alkali elements. Although the anodes in sodium-ion batteries show poorer rate capability than that in lithium-ion batteries, they still achieve a reversible sodium intercalation capacity of 275 mAh g −1 and similar cycling stability due to the conductive 3-D network, weakly ordered turbostratic structure and a large interlayer spacing between graphene sheets. The feature of high capacity and stable cycling performance makes PAN-CNFs to be promising candidates as electrodes in rechargeable sodium-ion batteries and lithium-ion batteries

  7. Nanocomposites Derived From a Low-Color Aromatic Polyimide (CP2) and Amine-Functionalized Vapor-Grown Carbon Nanofibers: In Situ Polymerization and Characterization (Preprint)

    Science.gov (United States)

    2007-01-01

    chemical modification of CNF.6,7 Recently, we have developed an effective method to directly arylcarbonylate vapor- grown carbon nanofibers (VGCNF...nanocomposites in a one-pot fashion.6 Subsequently, in addition to extending the applicability of this functionalization method to MWNT, we have found useful...temperature water was added. The resulting precipitate was collected, washed with diluted ammonium hydroxide and Soxhlet extracted with water for

  8. Co3O4 Nanoparticle-Decorated N-Doped Mesoporous Carbon Nanofibers as an Efficient Catalyst for Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Hairong Xue

    2017-06-01

    Full Text Available A low cost, durable, and efficient electrocatalyst for oxygen reduction reactions (ORR is essential for high-performance fuel cells. Here, we fabricated Co3O4 nanoparticles (NPs anchored on N-doped mesoporous carbon nanofibers (Co3O4/NMCF by electrospinning combined with the simple heat treatment. Within this composite, carbon nanofibers possess a mesoporous structure, contributed to obtain a high surface area, which can facilitate the infiltration of electrolyte. Moreover, this one-dimensional (1D carbon nanofiber also acts as a 1D conductive channel, effectively improving the transmission of electrons. In addition, the doping of the N element with high content combined with homogenously distributed Co3O4 NPs can significantly enhance the ORR electrocatalytic activity. Benefiting from the advantages of material and structure, the Co3O4/NMCF catalyst favors a four electron transfer process in alkaline media, exhibiting good ORR electrocatalytic activity, and its durability is much better than that of commercial Pt/C.

  9. Electrospun Nanofibers Applications in Dentistry

    Directory of Open Access Journals (Sweden)

    Seog-Jin Seo

    2016-01-01

    Full Text Available Nanofibrous structures exhibit many interesting features, such as high surface area and surface functionalization and porosity in the range from submicron to nanoscale, which mimics the natural extracellular matrix. In particular, electrospun nanofibers have gained great attention in the field of tissue engineering due to the ease of fabrication and tailorability in pore size, scaffold shape, and fiber alignment. For the reasons, recently, polymeric nanofibers or bioceramic nanoparticle-incorporated nanofibers have been used in dentistry, and their nanostructure and flexibility have contributed to highly promotive cell homing behaviors, resulting in expecting improved dental regeneration. Here, this paper focuses on recently applied electrospun nanofibers in dentistry in the range from the process to the applications.

  10. 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}.

  11. Controllable growth of Prussian blue nanostructures on carboxylic group-functionalized carbon nanofibers and its application for glucose biosensing

    International Nuclear Information System (INIS)

    Wang Li; Ye Yinjian; Zhu Haozhi; Song Yonghai; He Shuijian; Xu Fugang; Hou Haoqing

    2012-01-01

    Glucose detection is very important in biological analysis, clinical diagnosis and the food industry, and especially for the routine monitoring of diabetes. This work presents an electrochemical approach to the detection of glucose based on Prussian blue (PB) nanostructures/carboxylic group-functionalized carbon nanofiber (FCNF) nanocomposites. The hybrid nanocomposites were constructed by growing PB onto the FCNFs. The obtained PB–FCNF nanocomposites were characterized by scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The mechanism of formation of PB–FCNF nanocomposites was investigated and is discussed in detail. The PB–FCNF modified glassy carbon electrode (PB–FCNF/GCE) shows good electrocatalysis toward the reduction of H 2 O 2 , a product from the reduction of O 2 followed by glucose oxidase (GOD) catalysis of the oxidation of glucose to gluconic acid. Further immobilizing GOD on the PB–FCNF/GCE, an amperometric glucose biosensor was achieved by monitoring the generated H 2 O 2 under a relatively negative potential. The resulting glucose biosensor exhibited a rapid response of 5 s, a low detection limit of 0.5 μM, a wide linear range of 0.02–12 mM, a high sensitivity of 35.94 μA cm −2 mM −1 , as well as good stability, repeatability and selectivity. The sensor might be promising for practical application. (paper)

  12. Improvement in Field Electron Emission Performance of Natural-Precursor-Grown Carbon Nanofibers by Thermal Annealing in Argon Atmosphere

    Science.gov (United States)

    Ghosh, Pradip; Zamri, Mohd; Ghosh, Debasish; Soga, Tetsuo; Jimbo, Takashi; Hashimoto, Shinobu; Ohashi, Shuho; Tanemura, Masaki

    2011-01-01

    Carbon nanofibers (CNFs) were grown on a graphite substrate by the spray pyrolysis of a botanical hydrocarbon, turpentine oil, using ferrocene as the catalyst and sulfur as the promoter. The as-grown CNFs were annealed at 450 °C for 30 min in an air, and then at 1800 °C in an argon atmosphere for 2 h. The annealed CNFs have better degree of crystallinity and reduced number of defects compared with the as-grown CNFs confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and thermogravimetric analysis. The as-grown and annealed CNFs were found to be effective electron emitters with turn-on fields of 3.2 and 2.1 V/µm, respectively. The improvement in field emission (FE) performance can be explained in terms of the higher degree of graphitization of the CNFs after thermal annealing. This improved FE performance of the natural precursor grown CNFs was comparable to the FE performance level attainable for the conventional carbon nanomaterials grown using petroleum products. Thus, it was considered that the use of petroleum products could be avoidable for CNF growth and that CNFs grown using ecofriendly materials are very promising for the application in future field emission displays (FEDs).

  13. Alignment of carbon nanotubes comprising magnetically sensitive metal oxides in heat transfer nanofluids

    International Nuclear Information System (INIS)

    Hong, Haiping; Luan, Xinning; Horton, Mark; Li, Chen; Peterson, G.P.

    2011-01-01

    Highlights: → High speed microscopy was utilized to allow real time visualization of the movement of nanoparticles including SWNT and Fe 2 O 3 . → This electrostatic force induced alignment could maintain nanotube perfect conjugate structures which result in excellent thermal, electrical, and mechanical properties. → The alignment of the carbon nanotubes in nanosuspensions may offer new opportunities for the development of nanofluids. → These nanosuspensions also could be used in films, polymer composites, transparent electrodes, electromagnetic interference shielding, new sensors, etc. - Abstract: High speed microscopy was utilized to allow real time visualization of the movement of single walled carbon nanotubes (SWNT) with magnetically sensitive nanoparticles (Fe 2 O 3 ) and a chemical surfactant (NaDSSB) in water. Initially, entangled SWNT, Fe 2 O 3 and NaDSSB mixtures were randomly dispersed in the fluid. Upon extended exposure to the magnetic field, the mixture slowly vibrated, the nanoparticles straightened and aligned with respect to the magnetic field. The aligned nanoparticle chains appeared to be continuous and unbroken, forming a combination of aligned particles and clusters. Because of the semi-continuous nature of these nanosuspensions and the inherent viscosity of the fluid, some minutes are required for the mixtures to respond to the applied magnetic field and align. Time dependent thermal conductivity experiments indicate that the alignment process dominates the thermal conductivity enhancement as opposed to micro convection. Scanning Electron Microscopy (SEM) images also show that the SWNT and Fe 2 O 3 particles are well aligned under the influence of the magnetic field. Verification of the assumption that electrostatic attraction between nanotube/surfactant and metal oxides makes aggregation happen was obtained, by changing the nature of the charge of the surfactant from a negative charge (NaSDDB) to a positive charge (CTAB). Compared

  14. Alignment of carbon nanotubes comprising magnetically sensitive metal oxides in heat transfer nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Haiping, E-mail: Haiping.Hong@sdsmt.edu [Department of Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Luan, Xinning; Horton, Mark [Department of Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Li, Chen [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Peterson, G.P. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2011-10-20

    Highlights: {yields} High speed microscopy was utilized to allow real time visualization of the movement of nanoparticles including SWNT and Fe{sub 2}O{sub 3}. {yields} This electrostatic force induced alignment could maintain nanotube perfect conjugate structures which result in excellent thermal, electrical, and mechanical properties. {yields} The alignment of the carbon nanotubes in nanosuspensions may offer new opportunities for the development of nanofluids. {yields} These nanosuspensions also could be used in films, polymer composites, transparent electrodes, electromagnetic interference shielding, new sensors, etc. - Abstract: High speed microscopy was utilized to allow real time visualization of the movement of single walled carbon nanotubes (SWNT) with magnetically sensitive nanoparticles (Fe{sub 2}O{sub 3}) and a chemical surfactant (NaDSSB) in water. Initially, entangled SWNT, Fe{sub 2}O{sub 3} and NaDSSB mixtures were randomly dispersed in the fluid. Upon extended exposure to the magnetic field, the mixture slowly vibrated, the nanoparticles straightened and aligned with respect to the magnetic field. The aligned nanoparticle chains appeared to be continuous and unbroken, forming a combination of aligned particles and clusters. Because of the semi-continuous nature of these nanosuspensions and the inherent viscosity of the fluid, some minutes are required for the mixtures to respond to the applied magnetic field and align. Time dependent thermal conductivity experiments indicate that the alignment process dominates the thermal conductivity enhancement as opposed to micro convection. Scanning Electron Microscopy (SEM) images also show that the SWNT and Fe{sub 2}O{sub 3} particles are well aligned under the influence of the magnetic field. Verification of the assumption that electrostatic attraction between nanotube/surfactant and metal oxides makes aggregation happen was obtained, by changing the nature of the charge of the surfactant from a negative

  15. Fabrication of composite microstructures by capillarity-driven wetting of aligned carbon nanotubes with polymers

    Energy Technology Data Exchange (ETDEWEB)

    GarcIa, E J [Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hart, A J [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Wardle, B L [Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Slocum, A H [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2007-04-25

    The interaction, or wetting, of long aligned carbon nanotube (CNT) forests with off-the-shelf (no solvent added) commercial thermoset polymers is investigated experimentally. A technique for creating vertically aligned CNT composite microstructures of various shapes is presented. The effective wetting of the forests, as evidenced by a lack of voids, by three polymers with widely varying viscosities supports the feasibility of using CNT forests in large-scale hybrid advanced composite architectures. Among various routes identified for the polymer to penetrate the forest, capillarity-driven wetting along the CNT axis is the preferred route. Aligned CNT microstructures are useful in many applications including test structures for direct mechanical and multifunctional property characterization of the aligned CNT-polymer composite materials.

  16. Aligning ecology and markets in the forest carbon cycle

    Science.gov (United States)

    Matthew D. Hurteau; Bruce A. Hungate; George W. Koch; Malcolm P. North; Gordon R Smith

    2013-01-01

    A forest carbon (C) offset is a quantifiable unit of C that is commonly developed at the local or regional project scale and is designed to counterbalance anthropogenic C emissions by sequestering C in trees. In capand- trade programs, forest offsets have market value if the sequestered C is additional (more than would have occurred in the absence of the project) and...

  17. Structure-Processing-Property Interrelationships of Vapor Grown Carbon Nanofiber, Single-Walled Carbon Nanotube and Functionalized Single-Walled Carbon Nanotube - Polypropylene Nanocomposites

    Science.gov (United States)

    Radhakrishnan, Vinod Karumathil

    This dissertation describes the first use of a design of experiments approach to investigate the interrelationships between structure, processing, and properties of melt extruded polypropylene (PP) carbon nanomaterial composites. The effect of nanomaterial structure was evaluated by exploring the incorporation of vapor grown carbon nanofibers (VGCFs), or pristine or functionalized single-walled carbon nanotubes (SWNTs or C12SWNTs) in polypropylene, while the effect of processing was investigated by studying the influence of melt extrusion temperature, speed, and time. The nanomaterials and PP were combined by an initial mixing method prior to melt extrusion. The nanocomposite properties were characterized by a combination of morphological, rheological, and thermal methods. Preliminary investigations into the effects of the initial mixing method revealed that the distribution of nanomaterials obtained after the mixing had a considerable influence on the properties of the final melt extruded nanocomposite. Dry mixing (DM) resulted in minimal adhesion between nanomaterials and PP during initial mixing; the majority of nanomaterials descended to the bottom. Hot coagulation (HC) mixing resulted in extremely high degrees of interaction between the nanomaterials and PP chains. Rotary evaporation (RE) mixing resulted in nanomaterial distribution uniformity between that obtained from DM and HC. Employing design of experiments to investigate the effects of structure and processing conditions on melt extruded PP nanocomposite properties revealed several interesting effects. The effect of processing conditions varied depending on the degree of nanomaterial distribution in PP attained prior to melt processing. Increasing melt extrusion temperature increased the decomposition temperature (Td) of PP/C12SWNT obtained from HC mixing but decreased T d of PP/C12SWNT obtained from RE mixing. Higher melt extrusion screw speed, on the other hand, significantly improved the nanocomposite

  18. Aligned carbon nanotube-Pt composite fuel cell catalyst by template electrodeposition

    OpenAIRE

    Nagle, Lorraine C.; Rohan, James F.

    2008-01-01

    Solution phase deposition of aligned arrays of carbon nanotubes (CNTs) in a platinum (Pt) matrix cornposite is demonstrated. The catalyst material is electrodeposited in an oriented manner on the nanoscale using anodised aluminium oxide (AAO) templates. The catalyst performance of the composite for the oxidation of methanol is shown. The carbon monoxide (CO) tolerance is increased and the catalyst function is improved by minimising the influence of adsorbed CO on the kinetics of the methanol ...

  19. Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes

    International Nuclear Information System (INIS)

    Chen Wei; Tao Xiaoming

    2006-01-01

    We reported a simple method to fabricate polymer nanocomposites with single-walled carbon nanotubes (SWNTs) having exceptional alignment and improved mechanical properties. The composite films were fabricated by casting a suspension of single walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. The orientation as well as dispersion of nanotubes was determined by scanning electron microscopy, transmission electron microscopy and polarized Raman spectroscopy. The macroscopic alignment probably results from solvent-polymer interaction induced orientation of soft segment chain during swelling and moisture curing. The tensile behavior of the aligned nanotube composite film was also studied. At a 0.5 wt.% nanotube loading, a 1.9-fold increase in Young's modulus was achieved

  20. Vertically aligned carbon nanotube field emitter arrays with Ohmic base contact to silicon by Fe-catalyzed chemical vapor deposition

    NARCIS (Netherlands)

    Morassutto, M.; Tiggelaar, Roald M.; Smithers, M.A.; Smithers, M.A.; Gardeniers, Johannes G.E.

    2016-01-01

    Abstract In this study, dense arrays of aligned carbon nanotubes are obtained by thermal catalytic chemical vapor deposition, using Fe catalyst dispersed on a thin Ta layer. Alignment of the carbon nanotubes depends on the original Fe layer thickness from which the catalyst dispersion is obtained by

  1. Crystallization Behavior of Poly(ethylene oxide) in Vertically Aligned Carbon Nanotube Array.

    Science.gov (United States)

    Sheng, Jiadong; Zhou, Shenglin; Yang, Zhaohui; Zhang, Xiaohua

    2018-03-27

    We investigate the effect of the presence of vertically aligned multiwalled carbon nanotubes (CNTs) on the orientation of poly(ethylene oxide) (PEO) lamellae and PEO crystallinity. The high alignment of carbon nanotubes acting as templates probably governs the orientation of PEO lamellae. This templating effect might result in the lamella planes of PEO crystals oriented along a direction parallel to the long axis of the nanotubes. The presence of aligned carbon nanotubes also gives rise to the decreases in PEO crystallinity, crystallization temperature, and melting temperature due to the perturbation of carbon nanotubes to the crystallization of PEO. These effects have significant implications for controlling the orientation of PEO lamellae and decreasing the crystallinity of PEO and thickness of PEO lamellae, which have significant impacts on ion transport in PEO/CNT composite and the capacitive performance of PEO/CNT composite. Both the decreased PEO crystallinity and the orientation of PEO lamellae along the long axes of vertically aligned CNTs give rise to the decrease in the charge transfer resistance, which is associated with the improvements in the ion transport and capacitive performance of PEO/CNT composite.

  2. Multilevel, Multicomponent Microarchitectures of Vertically-Aligned Carbon Nanotubes for Diverse Applications

    Science.gov (United States)

    2011-01-31

    plate were synthesized by pyrolysis of iron phthalocyanine (FePc) in Ar/H2 atmosphere at 1100 C as we previously reported,19 while nonpatterned VA...Coating of Titanium Dioxide on Aligned Carbon Nanotubes for Controlled Syntheses of Photo- electronic Nanomaterials . Adv. Mater. 2007, 19, 1239– 1243

  3. Split Sn-Cu Alloys on Carbon Nanofibers by One-step Heat Treatment for Long-Lifespan Lithium-Ion Batteries

    International Nuclear Information System (INIS)

    Shen, Zhen; Hu, Yi; Chen, Renzhong; He, Xia; Chen, Yanli; Shao, Hanfeng; Zhang, Xiangwu; Wu, Keshi

    2017-01-01

    Highlights: • Spilt Sn–Cu alloys and amorphous CNF anodes are introduced. • Sn–Cu–CNFs were prepared by one-step carbonization-alloying reactions. • The spilt Sn–Cu alloys consist of Cu 6 Sn 5 and Cu 3 Sn. • The coexistence of Cu 6 Sn 5 and Cu 3 Sn led to the enhanced cycle durability. - Abstract: To develop next-generation lithium-ion batteries (LIBs) with novel designs, reconsidering traditional materials with enhanced cycle stability and excellent rate performance is crucial. We herein report the successful preparation of three-dimensional (3D) composites in which spilt Sn–Cu alloys are uniformly dispersed in an amorphous carbon nanofiber matrix (Sn–Cu–CNFs) via one-step carbonization-alloying reactions. The spilt Sn–Cu alloys consist of active Cu 6 Sn 5 and inactive Cu 3 Sn, and are controllable by optimization of the carbonization-alloying reaction temperature. The 3D carbon nanofiber framework allowed the Sn–Cu–CNFs to be used directly as anodes in lithium-ion batteries without the requirement for polymer binders or electrical conductors. These composite electrodes exhibited a stable cyclability with a discharge capacity of 400 mA h g −1 at a high current density of 1.0 A g −1 after 1200 cycles, as well as an excellent rate capability, which could be attributed to the improved electrochemical properties of the Sn–Cu–CNFs provided by the buffering effect of Cu 3 Sn and the 3D carbon nanofiber framework. This one-step synthesis is expected to be widely applicable in the targeted structural design of traditional tin-based anode materials.

  4. Production, characterization, and mechanical behavior of cementitious materials incorporating carbon nanofibers.

    Science.gov (United States)

    2012-08-01

    Carbon nanotubes (CNTs) and carbon nanofirbers (CNFs) have excellent properties : (mechanical, electrical, magnetic, etc.), which can make them effective : nanoreinforcements for improving the properties of materials. The incorporation of : CNT/Fs in...

  5. Improved energy storage, magnetic and electrical properties of aligned, mesoporous and high aspect ratio nanofibers of spinel-NiMn2O4

    Science.gov (United States)

    Bhagwan, Jai; Rani, Stuti; Sivasankaran, V.; Yadav, K. L.; Sharma, Yogesh

    2017-12-01

    Spinel-NiMn2O4 (NMO) nanofibers of high aspect ratio, high surface area (50 m2 g-1) and homogeneous pore size distribution are fabricated by electrospinning process and characterized by XRD, FTIR, XPS, BET, FESEM, TEM techniques. Further, multifunctional properties (energy storage properties, magnetic and electrical properties) of NMO nanofibers are also examined. High specific capacitance (Cs) of 410 (±5) F g-1 at 1 A g-1, good rate capability and high cycling stability (up to 5000 cycles) are demonstrated by NMO nanofibers. Furthermore, NMO-based solid-state symmetric supercapacitor (SSSC) shows a high Cs of 170 (±5) F g-1 at 0.5 A g-1 in potential range of 0.0V-2.0 V and exhibits excellent energy density of ∼95 W h kg-1 and power density of 1030 W Kg-1. The above storage properties i.e. high energy density and output voltage of 2.0 V are further supplemented by lighting up a red colored LED (1.8 V @ current 20 mA) at least for 5 min. The ionic diffusion coefficient of NMO based electrode is found to be ∼4.84 × 10-11 cm2 s-1. Magnetic and dielectric properties of NMO nanofibers are also examined and results are discussed.

  6. Tuning vertical alignment and field emission properties of multi-walled carbon nanotube bundles

    Science.gov (United States)

    Sreekanth, M.; Ghosh, S.; Srivastava, P.

    2018-01-01

    We report the growth of vertically aligned carbon nanotube bundles on Si substrate by thermal chemical vapor deposition technique. Vertical alignment was achieved without any carrier gas or lithography-assisted deposition. Growth has been carried out at 850 °C for different quantities of solution of xylene and ferrocene ranging from 2.25 to 3.00 ml in steps of 0.25 ml at a fixed concentration of 0.02 gm (ferrocene) per ml. To understand the growth mechanism, deposition was carried out for different concentrations of the solution by changing only the ferrocene quantity, ranging from 0.01 to 0.03 gm/ml. A tunable vertical alignment of multi-walled carbon nanotubes (CNTs) has been achieved by this process and examined by scanning and transmission electron microscopic techniques. Micro-crystalline structural analysis has been done using Raman spectroscopy. A systematic variation in field emission (FE) current density has been observed. The highest FE current density is seen for the film grown with 0.02 gm/ml concentration, which is attributed to the better alignment of CNTs, less structural disorder and less entanglement of CNTs on the surface. The alignment of CNTs has been qualitatively understood on the basis of self-assembled catalytic particles.

  7. 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.

  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. 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)

  10. 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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Inducing porosity and growing carbon nanofibers in ferroin perchlorate: An example of morphological transitions in coordination complexes

    Science.gov (United States)

    Avraham, Efrat Shawat; Fleker, Ohad; Benisvy, Laurent; Oakes, Landon; Pint, Cary L.; Nessim, Gilbert D.

    2017-09-01

    Inducing porosity in solid coordination complex crystals, which are an important class of catalysts, is critical for many applications where a high surface area is required. However, unlike metal organic frameworks (MOFs), fabrication of porous coordination crystals remains a significant challenge. Here we demonstrate a simple method to produce and modulate porosity in coordination complex crystals using ferroin perchlorate, a model system that combines a common ionic complex with a very reactive counter-ion. Using thermal chemical vapor deposition (CVD), we show that by annealing ferroin perchlorate crystals at 350 °C under a flow of ethylene, hydrogen, argon, and oxygen, we induced pores in the crystal. We demonstrate that small amounts of oxygen, which may combine with hydrogen to form water, are essential for pore formation. We also demonstrate that pore size and density can be easily controlled by varying the ethylene flow. Upon raising the annealing temperature to 500 °C, we observed a second transition in which carbon nanofibers (CNFs) grew from the porous crystal. This approach represents a simple and effective method for the synthesis of porous materials with good control over pore size and density. It also enables the synthesis of complex networks of nanostructures (in our case CNFs) by simply varying process parameters such as temperature and gas flows. This represents an important advance for the fabrication of porous coordination complex crystals.

  13. Electronic, Magnetic, and Transport Properties of Polyacrylonitrile-Based Carbon Nanofibers of Various Widths: Density-Functional Theory Calculations

    Science.gov (United States)

    Partovi-Azar, P.; Panahian Jand, S.; Kaghazchi, P.

    2018-01-01

    Edge termination of graphene nanoribbons is a key factor in determination of their physical and chemical properties. Here, we focus on nitrogen-terminated zigzag graphene nanoribbons resembling polyacrylonitrile-based carbon nanofibers (CNFs) which are widely studied in energy research. In particular, we investigate magnetic, electronic, and transport properties of these CNFs as functions of their widths using density-functional theory calculations together with the nonequilibrium Green's function method. We report on metallic behavior of all the CNFs considered in this study and demonstrate that the narrow CNFs show finite magnetic moments. The spin-polarized electronic states in these fibers exhibit similar spin configurations on both edges and result in spin-dependent transport channels in the narrow CNFs. We show that the partially filled nitrogen dangling-bond bands are mainly responsible for the ferromagnetic spin ordering in the narrow samples. However, the magnetic moment becomes vanishingly small in the case of wide CNFs where the dangling-bond bands fall below the Fermi level and graphenelike transport properties arising from the π orbitals are recovered. The magnetic properties of the CNFs as well as their stability have also been discussed in the presence of water molecules and the hexagonal boron nitride substrate.

  14. Application of polyacrylonitrile nanofibers decorated with magnetic carbon dots as a resonance light scattering sensor to determine famotidine.

    Science.gov (United States)

    Maleki, Somayeh; Madrakian, Tayyebeh; Afkhami, Abbas

    2018-05-01

    In this study, a novel resonance light scattering (RLS) sensor was synthesized using polyacrylonitrile nanofibers decorated with magnetic carbon dots (MCDs@NFs) nanocomposite and applied for famotidine (FMD) determination. The MCDs@NFs nanocomposite was synthesized by combining electrospinning and a simple one-step hydrothermal method. Different methods were applied in order to characterize the MCDs@NFs nanocomposite such as: scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Light scattering properties of the synthesized nanocomposite in the presence or absence of FMD have been selected as the detection signal considering the fact that FMD addition increases the RLS intensities of the system. Thus, the prepared nanocomposite was employed as a RLS sensor to detect FMD. A linear response was observed under the optimal conditions in range of 0.15-50.0μmolL -1 with detection limit of 0.04μmolL -1 . The MCDs@NFs nanocomposite was effectively capable in determining FMD in real samples and the results were close to those results obtained by reversed-phase HPLC method (RP-HPLC). Copyright © 2018 Elsevier B.V. All rights reserved.

  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. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    International Nuclear Information System (INIS)

    Saidin, M.A.R.; Ismail, A.F.; Sanip, S.M.; Goh, P.S.; Aziz, M.; Tanemura, M.

    2012-01-01

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I D /I G value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  17. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    Energy Technology Data Exchange (ETDEWEB)

    Saidin, M.A.R. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ismail, A.F., E-mail: afauzi@utm.my [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sanip, S.M.; Goh, P.S.; Aziz, M. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Tanemura, M. [Department of Frontier Material, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2012-01-31

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I{sub D}/I{sub G} value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  18. Improved supercapacitor performance of MnO2-electrospun carbon nanofibers electrodes by mT magnetic field

    Science.gov (United States)

    Zeng, Zheng; Liu, Yiyang; Zhang, Wendi; Chevva, Harish; Wei, Jianjun

    2017-08-01

    This work reports on a finding of mT magnetic field induced energy storage enhancement of MnO2-based supercapacitance electrodes (magneto-supercapacitor). Electrodes with MnO2 electrochemically deposited at electrospun carbon nanofibers (ECNFs) film are studied by cyclic voltammetry (CV), galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), and life cycle stability tests in the presence/absence of milli-Tesla (mT) magnetic fields derived by Helmholtz coils. In the presence of a 1.34 mT magnetic field, MnO2/ECNFs shows a magneto-enhanced capacitance of 141.7 F g-1 vs. 119.2 F g-1 (∼19% increase) with absence of magnetic field at a voltage sweeping rate of 5 mV s-1. The mechanism of the magneto-supercapacitance is discussed and found that the magnetic susceptibility of the MnO2 significantly improves the electron transfer of a pseudo-redox reaction of Mn(IV)/Mn(III) at the electrode, along with the magnetic field induced impedance effect, which may greatly enhance the interface charge density, facilitate electrolyte transportation, and improve the efficiency of cation intercalation/de-intercalation of the pseudocapacitor under mT-magnetic field exposure, resulting in enhancement of energy storage capacitance and longer charge/discharge time of the MnO2/ECNFs electrode without sacrificing its life cycle stability.

  19. Silver-incorporated composites of Fe2O3 carbon nanofibers as anodes for high-performance lithium batteries

    Science.gov (United States)

    Zou, Mingzhong; Li, Jiaxin; Wen, WeiWei; Chen, Luzhuo; Guan, Lunhui; Lai, Heng; Huang, Zhigao

    2014-12-01

    Composites of Ag-incorporated carbon nanofibers (CNFs) confined with Fe2O3 nanoparticles (Ag-Fe2O3/CNFs) have been synthesized through an electrospinning method and evaluated as anodes for lithium batteries (LIBs). The obtained Ag-Fe2O3/CNF anodes show good LIB performance with a capacity of 630 mAh g-1 tested at 800 mA g-1 after 150 cycles with almost no capacity loss and superb rate performance. The obtained properties for Ag-Fe2O3/CNF anodes are much better than Fe2O3/CNF anodes without Ag-incorporating. In addition, the low-temperature LIB performances for Ag-Fe2O3/CNF anodes have been investigated for revealing the enhanced mechanism of Ag-incorporating. The superior electrochemical performances of the Ag-Fe2O3/CNFs are associated with a synergistic effect of the CNF matrix and the highly conducting Ag incorporating. This unique configuration not only facilitates electron conduction especially at a relative temperature, but also maintains the structural integrity of active materials. Meanwhile, the related analysis of the AC impedance spectroscopy and the corresponding hypothesis for DC impedance confirm that such configuration can effectively enhance the charge-transfer efficiency and the lithium diffusion coefficient. Therefore, CNF-supported coupled with Ag incorporating synthesis supplied a promising route to obtain Fe2O3 based anodes with high-performance LIBs especially at low temperature.

  20. Facile Synthesis of Indium Sulfide/Flexible Electrospun Carbon Nanofiber for Enhanced Photocatalytic Efficiency and Its Application.

    Science.gov (United States)

    Han, Liu; Dong, Haohao; Mao, Dong; Hua, Baolv; Li, Qinyu; Fang, Dong

    2017-01-01

    Heterojunction system has been proved as one of the best architectures for photocatalyst owing to extending specific surface area, expanding spectral response range, and increasing photoinduced charges generation, separation, and transmission, which can provide better light absorption range and higher reaction site. In this paper, Indium Sulfide/Flexible Electrospun Carbon Nanofiber (In 2 S 3 /CNF) heterogeneous systems were synthesized by a facile one-pot hydrothermal method. The results from characterizations of SEM, TEM, XRD, Raman, and UV-visible diffuse reflectance spectroscopy displayed that flower-like In 2 S 3 was deposited on the hair-like CNF template, forming a one-dimensional nanofibrous network heterojunction photocatalyst. And the newly prepared In 2 S 3 /CNF photocatalysts exhibit greatly enhanced photocatalytic activity compared to pure In 2 S 3 . In addition, the formation mechanism of the one-dimensional heterojunction In 2 S 3 /CNF photocatalyst is discussed and a promising approach to degrade Rhodamine B (RB) in the photocatalytic process is processed.

  1. Facile Synthesis of Indium Sulfide/Flexible Electrospun Carbon Nanofiber for Enhanced Photocatalytic Efficiency and Its Application

    Directory of Open Access Journals (Sweden)

    Liu Han

    2017-01-01

    Full Text Available Heterojunction system has been proved as one of the best architectures for photocatalyst owing to extending specific surface area, expanding spectral response range, and increasing photoinduced charges generation, separation, and transmission, which can provide better light absorption range and higher reaction site. In this paper, Indium Sulfide/Flexible Electrospun Carbon Nanofiber (In2S3/CNF heterogeneous systems were synthesized by a facile one-pot hydrothermal method. The results from characterizations of SEM, TEM, XRD, Raman, and UV-visible diffuse reflectance spectroscopy displayed that flower-like In2S3 was deposited on the hair-like CNF template, forming a one-dimensional nanofibrous network heterojunction photocatalyst. And the newly prepared In2S3/CNF photocatalysts exhibit greatly enhanced photocatalytic activity compared to pure In2S3. In addition, the formation mechanism of the one-dimensional heterojunction In2S3/CNF photocatalyst is discussed and a promising approach to degrade Rhodamine B (RB in the photocatalytic process is processed.

  2. Adsorption of phosphate from aqueous solution using iron-zirconium modified activated carbon nanofiber: Performance and mechanism.

    Science.gov (United States)

    Xiong, Weiping; Tong, Jing; Yang, Zhaohui; Zeng, Guangming; Zhou, Yaoyu; Wang, Dongbo; Song, Peipei; Xu, Rui; Zhang, Chen; Cheng, Min

    2017-05-01

    Phosphate (P) removal is significant for the prevention of eutrophication in natural waters. In this paper, a novel adsorbent for the removal of P from aqueous solution was synthesized by loading zirconium oxide and iron oxide onto activated carbon nanofiber (ACF-ZrFe) simultaneously. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that P adsorption was highly pH dependent and the optimum pH was found to be 4.0. The isotherm of adsorption could be well described by the Langmuir model and the maximum P adsorption capacity was estimated to be 26.3mgP/g at 25°C. The kinetic data were well fitted to the pseudo-second-order equation, indicating that chemical sorption was the rate-limiting step. Moreover, co-existing ions including sulfate (SO 4 2- ), chloride (Cl - ), nitrate (NO 3 - ) and fluoride (F - ) exhibited a distinct effect on P adsorption with the order of F - >NO 3 - >Cl - >SO 4 2- . Further investigations by FT-IR spectroscopy and pH variations associated with the adsorption process revealed that ligands exchange and electrostatic interactions were the dominant mechanisms for P adsorption. The findings reported in this work highlight the potential of using ACF-ZrFe as an effective adsorbent for the removal of P in natural waters. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Trimodal nanoelectrode array for precise deep brain stimulation: prospects of a new technology based on carbon nanofiber arrays.

    Science.gov (United States)

    Li, J; Andrews, R J

    2007-01-01

    Although deep brain stimulation (DBS) has recently been shown to be effective for neurological disorders such as Parkinson's disease, there are many limitations of the current technology: the large size of current microelectrodes (approximately 1 mm diameter); the lack of monitoring of local brain electrical activity and neurotransmitters (e.g. dopamine in Parkinson's disease); the open-loop nature of the stimulation (i.e. not guided by brain electrochemical activity). Reducing the size of the monitoring and stimulating electrodes by orders of magnitude (to the size of neural elements) allows remarkable improvements in both monitoring (spatial resolution, temporal resolution, and sensitivity) and stimulation. Carbon nanofiber nanoelectrode technology offers the possibility of trimodal arrays (monitoring electrical activity, monitoring neurotransmitter levels, precise stimulation). DBS can then be guided by changes in brain electrical activity and/or neurotransmitter levels (i.e. closed-loop DBS). Here, we describe the basic manufacture and electrical characteristics of a prototype nanoelectrode array for DBS, as well as preliminary studies with electroconductive polymers necessary to optimize DBS in vivo. An approach such as the nanoelectrode array described here may offer a generic electrical-neural interface for use in various neural prostheses.

  4. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Preparation of well-aligned carbon nanotubes by pyrolysis of phenolic resin in anodic alumina pores

    Science.gov (United States)

    Li, Ke-Zhi; Wei, Jian; Li, He-Jun; Zhang, Yu-Lei; Wang, Chuang; Hou, Dang-She

    2007-07-01

    Well-aligned carbon nanotubes (CNTs) of high quality were synthesized by pyrolysis of phenolic resin at 800 °C in anodic alumina oxide (AAO) pores under argon protection. The innocuous source materials and safe operational conditions permit this method to synthesize well-aligned CNTs in large-scale and low cost. The formation mechanism of the synthesized CNTs is also proposed in this work by a series of visual sketches and is proved with obvious evidence. Firstly, phenolic resin nanotubes form in the template pores through the evaporation of solvent. Heat treatment then transfers these tubes into CNTs.

  6. The alignment of carbon nanotubes: an effective route to extend their excellent properties to macroscopic scale.

    Science.gov (United States)

    Sun, Xuemei; Chen, Tao; Yang, Zhibin; Peng, Huisheng

    2013-02-19

    To improve the practical application of carbon nanotubes, it is critically important to extend their physical properties from the nanoscale to the macroscopic scale. Recently, chemists aligned continuous multiwalled carbon nanotube (MWCNT) sheets and fibers to produce materials with high mechanical strength and electrical conductivity. This provided an important clue to the use of MWCNTs at macroscopic scale. Researchers have made multiple efforts to optimize this aligned structure and improve the properties of MWCNT sheets and fibers. In this Account, we briefly highlight the new synthetic methods and promising applications of aligned MWCNTs for organic optoelectronic materials and devices. We describe several general methods to prepare both horizontally and perpendicularly aligned MWCNT/polymer composite films, through an easy solution or melting process. The composite films exhibit the combined properties of being flexible, transparent, and electrically conductive. These advances may pave the way to new flexible substrates for organic solar cells, sensing devices, and other related applications. Similarly, we discuss the synthesis of aligned MWCNT/polymer composite fibers with interesting mechanical and electrical properties. Through these methods, we can incorporate a wide variety of soluble or fusible polymers for such composite films and fibers. In addition, we can later introduce functional polymers with conjugated backbones or side chains to improve the properties of these composite materials. In particular, cooperative interactions between aligned MWCNTs and polymers can produce novel properties that do not occur individually. Common examples of this are two types of responsive polymers, photodeformable azobenzene-containing liquid crystalline polymer and chromatic polydiacetylene. Aligning the structure of MWCNTs induces the orientation of azobenzene-containing mesogens, and produces photodeformable polymer elastomers. This strategy also solves the long

  7. 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, Roald M.; Gardeniers, Johannes G.E.; Lefferts, Leonardus; Seshan, Kulathuiyer

    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

  8. Graphene-doped carbon/Fe3O4 porous nanofibers with hierarchical band construction as high-performance anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    He, Jianxin; Zhao, Shuyuan; Lian, Yanping; Zhou, Mengjuan; Wang, Lidan; Ding, Bin; Cui, Shizhong

    2017-01-01

    Highlights: • GN@C/Fe 3 O 4 are synthesized via in-situ electrospinning and thermal treatment. • GN@C/Fe 3 O 4 show unique dark/light banding with a hierarchical porous structure. • Doped graphene induces a uniform distribution of smaller size Fe 3 O 4 nanoparticles. • Doped graphene provides more active sites and accommodate the volume change. • GN@C/Fe 3 O 4 electrode displays a reversible capacity of 872 mAh/g after 100 cycles. - Abstract: Porous graphene-doped carbon/Fe 3 O 4 (GN@C/Fe 3 O 4 ) nanofibers are synthesized via in-situ electrospinning and subsequent thermal treatment for use as lithium-ion battery anode materials. A polyacrylonitrile (PAN)/polymethyl methacrylate (PMMA) solution containing ferric acetylacetone and graphene oxide nanosheets is used as the electrospinning precursor solution. The resulting porous GN@C/Fe 3 O 4 nanofibers show unique dark/light banding and a hierarchical porous structure. These nanofibers have a Brunauer–Emmett–Teller (BET) specific surface area of 323.0 m 2 /g with a total pore volume of 0.337 cm 3 /g, which is significantly greater than that of a sample without graphene and C/Fe 3 O 4 nanofibers. The GN@C/Fe 3 O 4 nanofiber electrode displays a reversible capacity of 872 mAh/g at a current density of 100 mA/g after 100 cycles, excellent cycling stability, and superior rate capability (455 mA/g at 5 A/g). The excellent performance of porous GN@C/Fe 3 O 4 is attributed to the material’s unique structure, including its striped topography, hierarchical porous structure, and inlaid flexible graphene, which not only provides more accessible active sites for lithium-ion insertion and high-efficiency transport pathways for ions and electrons, but also accommodates the volume change associated with lithium insertion/extraction. Moreover, the zero-valent iron and graphene in the porous nanofibers enhance the conductivity of the electrodes.

  9. Electrospun nanofiber scaffolds: engineering soft tissues

    International Nuclear Information System (INIS)

    Kumbar, S G; Nukavarapu, S P; Laurencin, C T; James, R

    2008-01-01

    Electrospinning has emerged to be a simple, elegant and scalable technique to fabricate polymeric nanofibers. Pure polymers as well as blends and composites of both natural and synthetics have been successfully electrospun into nanofiber matrices. Physiochemical properties of nanofiber matrices can be controlled by manipulating electrospinning parameters to meet the requirements of a specific application. Such efforts include the fabrication of fiber matrices containing nanofibers, microfibers, combination of nano-microfibers and also different fiber orientation/alignments. Polymeric nanofiber matrices have been extensively investigated for diversified uses such as filtration, barrier fabrics, wipes, personal care, biomedical and pharmaceutical applications. Recently electrospun nanofiber matrices have gained a lot of attention, and are being explored as scaffolds in tissue engineering due to their properties that can modulate cellular behavior. Electrospun nanofiber matrices show morphological similarities to the natural extra-cellular matrix (ECM), characterized by ultrafine continuous fibers, high surface-to-volume ratio, high porosity and variable pore-size distribution. Efforts have been made to modify nanofiber surfaces with several bioactive molecules to provide cells with the necessary chemical cues and a more in vivo like environment. The current paper provides an overlook on such efforts in designing nanofiber matrices as scaffolds in the regeneration of various soft tissues including skin, blood vessel, tendon/ligament, cardiac patch, nerve and skeletal muscle

  10. Development of Radiation Processing to Functionalize Carbon Nanofiber to Use in Nanocomposites for Industrial Application

    International Nuclear Information System (INIS)

    Gondim de Andrade e Silva, Leonardo; Evora, Maria Cecilia

    2011-01-01

    The effects of ionizing radiation on carbon materials have been thoroughly investigated because of its importance in the fields of nuclear, medical, and materials science. Basically, the effect of ionizing radiation on carbon materials takes place as a displacement of carbon atoms from their amorphous or graphitic structures. For nanocarbon materials, only destructive effects were observed in early experiments involving bombardment of carbon nanotubes and fullerenes with ions. However, recent work reveals that radiation can exploit defect creation for novel materials development especially in electronic nanotechnology (Krasheninnikov et al., 2007)

  11. Micro-structural evolution and biomineralization behavior of carbon nanofiber/bioactive glass composites induced by precursor aging time.

    Science.gov (United States)

    Jia, Xiaolong; Tang, Tianhong; Cheng, Dan; Zhang, Cuihua; Zhang, Ran; Cai, Qing; Yang, Xiaoping

    2015-12-01

    Bioactive glass (BG)-containing carbon nanofibers (CNFs) are promising orthopaedic biomaterials. Herein, CNF composites were produced from electrospinning of polyacrylonitrile (PAN)/BG sol-gel precursor solution, followed by carbonization. Choosing 58S-type BG (mol%: 58.0% SiO2-26.3% CaO-15.7% P2O5) as the model, micro-structural evolution of CNF/BG composites was systematically evaluated in relating to aging times of BG precursor solution. With aging time prolonging, BG precursors underwent morphological changes from small sol clusters with loosely and randomly branched structure to highly crosslinked Si-network structure, showing continuous increase in solution viscosity. BG precursor solution with low viscosity could mix well with PAN solution, resulting in CNF composite with homogeneously distributed BG component. Whereas, BG precursor gel with densely crosslinked Si-network structure led to uneven distribution of BG component along final CNFs due to its significant phase separation from PAN component. Meanwhile, BG nanoparticles in CNFs demonstrated micro-structural evolution that they transited from weak to strong crystal state along with longer aging time. Biomineralization in simulated body fluid and in vitro osteoblasts proliferation were then applied to determine the bioactivity of CNF/BG composites. CNF/BG composites prepared from shorter aging time could induce both faster apatite deposition and cell proliferation rate. It was suggested weakly crystallized BG nanoparticles along CNFs dissolved fast and was able to provide numerous nucleation sites for apatite deposition, which also favored the proliferation of osteoblasts cells. Aging time could thus be a useful tool to regulate the biological features of CNF/BG composites. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Evaluating the mechanistic evidence and key data gaps in assessing the potential carcinogenicity of carbon nanotubes and nanofibers in humans

    Science.gov (United States)

    Kuempel, Eileen D.; Jaurand, Marie-Claude; Møller, Peter; Morimoto, Yasuo; Kobayashi, Norihiro; Pinkerton, Kent E.; Sargent, Linda M.; Vermeulen, Roel C. H.; Fubini, Bice; Kane, Agnes B.

    2016-01-01

    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. The findings of this review, in general, affirm those of the original evaluation on the inadequate or limited evidence of carcinogenicity for most types of CNTs and CNFs at this time, and possible carcinogenicity of one type of CNT (MWCNT-7). The key evidence gaps to be filled by research include: investigation of possible associations between in vitro and early-stage in vivo events that may be predictive of lung cancer or mesothelioma, and systematic analysis of dose–response relationships across materials, including evaluation of the influence of physico-chemical properties and experimental factors on the observation of nonmalignant and malignant endpoints. PMID:27537422

  13. 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%.

  14. Fabrication and Characterization of New Composite Tio2Carbon Nanofiber Anodic Catalyst Support for Direct Methanol Fuel Cell via Electrospinning Method.

    Science.gov (United States)

    Abdullah, N; Kamarudin, S K; Shyuan, L K; Karim, N A

    2017-12-06

    Platinum (Pt) is the common catalyst used in a direct methanol fuel cell (DMFC). However, Pt can lead towards catalyst poisoning by carbonaceous species, thus reduces the performance of DMFC. Thus, this study focuses on the fabrication of a new composite TiO 2 carbon nanofiber anodic catalyst support for direct methanol fuel cells (DMFCs) via electrospinning technique. The distance between the tip and the collector (DTC) and the flow rate were examined as influencing parameters in the electrospinning technique. To ensure that the best catalytic material is fabricated, the nanofiber underwent several characterizations and electrochemical tests, including FTIR, XRD, FESEM, TEM, and cyclic voltammetry. The results show that D18, fabricated with a flow rate of 0.1 mLhr -1 and DTC of 18 cm, is an ultrafine nanofiber with the smallest average diameter, 136.73 ± 39.56 nm. It presented the highest catalyst activity and electrochemical active surface area value as 274.72 mAmg -1 and 226.75m 2  g -1 PtRu , respectively, compared with the other samples.

  15. Fabrication and Characterization of New Composite Tio2 Carbon Nanofiber Anodic Catalyst Support for Direct Methanol Fuel Cell via Electrospinning Method

    Science.gov (United States)

    Abdullah, N.; Kamarudin, S. K.; Shyuan, L. K.; Karim, N. A.

    2017-12-01

    Platinum (Pt) is the common catalyst used in a direct methanol fuel cell (DMFC). However, Pt can lead towards catalyst poisoning by carbonaceous species, thus reduces the performance of DMFC. Thus, this study focuses on the fabrication of a new composite TiO2 carbon nanofiber anodic catalyst support for direct methanol fuel cells (DMFCs) via electrospinning technique. The distance between the tip and the collector (DTC) and the flow rate were examined as influencing parameters in the electrospinning technique. To ensure that the best catalytic material is fabricated, the nanofiber underwent several characterizations and electrochemical tests, including FTIR, XRD, FESEM, TEM, and cyclic voltammetry. The results show that D18, fabricated with a flow rate of 0.1 mLhr-1 and DTC of 18 cm, is an ultrafine nanofiber with the smallest average diameter, 136.73 ± 39.56 nm. It presented the highest catalyst activity and electrochemical active surface area value as 274.72 mAmg-1 and 226.75m2 g-1 PtRu, respectively, compared with the other samples.

  16. Vibrationally selective optimal control of alignment and orientation using infrared laser pulses: Application to carbon monoxide

    Science.gov (United States)

    Zou, Shiyang; Balint-Kurti, Gabriel G.; Manby, Frederick R.

    2007-07-01

    Optimal control methods are used to study molecular alignment and orientation using infrared laser pulses. High order molecule-field interactions are taken into account through the use of the electric-nuclear Born-Oppenheimer approximation [G. G. Balint-Kurti et al., J. Chem. Phys. 122, 084110 (2005)]. High degrees of alignment and orientation are achieved by optimized infrared laser pulses of duration on the order of one rotational period of the molecule. It is shown that, through the incorporation of a vibrational projection operator into the optimization procedure, it is possible not only to maximize the alignment and orientation but also to bring the whole system into a single prescribed vibrational manifold. Numerical calculations are performed for carbon monoxide using ab initio potential energies computed in the presence of external electric fields.

  17. Flexible transfer of aligned carbon nanotube films for integration at lower temperature

    International Nuclear Information System (INIS)

    Chai Yang; Gong Jingfeng; Zhang Kai; Chan, Philip C H; Yuen, Matthew M F

    2007-01-01

    The high growth temperature of carbon nanotubes (CNTs) hinders their direct assembly on temperature-sensitive substrates. We present a method to transfer an aligned CNT film at room temperature to overcome this problem. Using a 'liftoff' technique with hydrofluoric acid solution, we separate the aligned CNT film from the silicon substrate. The lifted-off CNT film is suspended in water, remaining intact and aligned due to the crowding effect. We then transfer the suspended film to various substrates that are sensitive to high temperature. To illustrate the quality of the transferred CNT film, we demonstrate that the thermal interface resistance of the transferred CNT film is comparable with that of as-grown CNT film. This transfer process can be extended to many microelectronics applications, such as field emission devices, integrated circuit interconnects and sensors, requiring processing temperatures not compatible with CNT growth

  18. Mechanics of capillary forming of aligned carbon nanotube assemblies.

    Science.gov (United States)

    Tawfick, Sameh; Zhao, Zhouzhou; Maschmann, Matthew; Brieland-Shoultz, Anna; De Volder, Michael; Baur, Jeffery W; Lu, Wei; Hart, A John

    2013-04-30

    Elastocapillary self-assembly is emerging as a versatile technique to manufacture three-dimensional (3D) microstructures and complex surface textures from arrangements of micro- and nanoscale filaments. Understanding the mechanics of capillary self-assembly is essential to engineering of properties such as shape-directed actuation, anisotropic wetting and adhesion, and mechanical energy transfer and dissipation. We study elastocapillary self-assembly (herein called "capillary forming") of carbon nanotube (CNT) microstructures, combining in situ optical imaging, micromechanical testing, and finite element modeling. By imaging, we identify sequential stages of liquid infiltration, evaporation, and solid shrinkage, whose kinetics relate to the size and shape of the CNT microstructure. We couple these observations with measurements of the orthotropic elastic moduli of CNT forests to understand how the dynamic of shrinkage of the vapor-liquid interface is coupled to the compression of the forest. We compare the kinetics of shrinkage to the rate of evporation from liquid droplets having the same size and geometry. Moreover, we show that the amount of shrinkage during evaporation is governed by the ability of the CNTs to slip against one another, which can be manipulated by the deposition of thin conformal coatings on the CNTs by atomic layer deposition (ALD). This insight is confirmed by finite element modeling of pairs of CNTs as corrugated beams in contact and highlights the coupled role of elasticity and friction in shrinkage and stability of nanoporous solids. Overall, this study shows that nanoscale porosity can be tailored via the filament density and adhesion at contact points, which is important to the development of lightweight multifunctional materials.

  19. Evaluation of protein adsorption onto a polyurethane nanofiber surface having different segment distributions

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Yuko; Koizumi, Gaku [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan); Sakamoto, Hiroaki, E-mail: hi-saka@u-fukui.ac.jp [Tenure-Track Program for Innovative Research, University of Fukui (Japan); Suye, Shin-ichiro [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan)

    2017-02-01

    Electrospinning is well known to be an effective method for fabricating polymeric nanofibers with a diameter of several hundred nanometers. Recently, the molecular-level orientation within nanofibers has attracted particular attention. Previously, we used atomic force microscopy to visualize the phase separation between soft and hard segments of a polyurethane (PU) nanofiber surface prepared by electrospinning. The unstretched PU nanofibers exhibited irregularly distributed hard segments, whereas hard segments of stretched nanofibers prepared with a high-speed collector exhibited periodic structures along the long-axis direction. PU was originally used to inhibit protein adsorption, but because the surface segment distribution was changed in the stretched nanofiber, here, we hypothesized that the protein adsorption property on the stretched nanofiber might be affected. We investigated protein adsorption onto PU nanofibers to elucidate the effects of segment distribution on the surface properties of PU nanofibers. The amount of adsorbed protein on stretched PU nanofibers was increased compared with that of unstretched nanofibers. These results indicate that the hard segment alignment on stretched PU nanofibers mediated protein adsorption. It is therefore expected that the amount of protein adsorption can be controlled by rotation of the collector. - Highlights: • The hard segments of stretched PU nanofibers exhibit periodic structures. • The adsorbed protein on stretched PU nanofibers was increased compared with PU film. • The hard segment alignment on stretched PU nanofibers mediated protein adsorption.

  20. 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.

  1. Large-scale and controllable synthesis of metal-free nitrogen-doped carbon nanofibers and nanocoils over water-soluble Na2CO3

    Science.gov (United States)

    Ding, Qian; Song, Xueyin; Yao, Xiujuan; Qi, Xiaosi; Au, Chak-Tong; Zhong, Wei; Du, Youwei

    2013-12-01

    Using acetylene as carbon source, ammonia as nitrogen source, and Na2CO3 powder as catalyst, we synthesized nitrogen-doped carbon nanofibers (N-CNFs) and carbon nanocoils (N-CNCs) selectively at 450°C and 500°C, respectively. The water-soluble Na2CO3 is removed through simple washing with water and the nitrogen-doped carbon nanomaterials can be collected in high purity. The approach is simple, inexpensive, and environment-benign; it can be used for controlled production of N-CNFs or N-CNCs. We report the role of catalyst, the effect of pyrolysis temperature, and the photoluminescence properties of the as-harvested N-CNFs and N-CNCs.

  2. Mechanical properties of aligned carbon nanotube architectures: origin from 3D morphology

    Science.gov (United States)

    Stein, Itai Y.; Wardle, Brian L.

    The scale-dependent properties of carbon nanotubes (CNTs) continue to motivate their study for next-generation material architectures. While recent work has shown that aligned CNT arrays can be made on the cm-scale, such systems exhibit properties that are orders of magnitude below those predicted by existing theories. This deviation mainly stems from the rudimentary assumptions made about the CNT morphology: CNTs are either devoid of local curvature (i.e. waviness) or have waviness that is easy to model, e.g. using helices and sine waves. Here, we use a simulation framework comprised of 105 CNTs with realistic 3D stochastic morphologies to elucidate the role morphology plays in the orders of magnitude over-prediction of the effective stiffness of aligned CNT structures. Application to aligned CNT polymer and carbon matrix nanocomposites reveals that the elimination of the torsion deformation mechanism, which dominates the effective compliance of CNT arrays, through CNT interactions with the matrix is responsible for the stiffness enhancement in CNT nanocomposites. This works paves the way to more accurate property prediction of CNT nanocomposites, and further work to predict the transport properties of aligned CNT architectures is planned.

  3. Synthesis and characterization of vertically aligned carbon nanotube forest for solid state fiber spinning.

    Science.gov (United States)

    Ryu, Seong Woo; Hwang, Jae Won; Hong, Soon Hyung

    2012-07-01

    Continuous carbon nanotubes (CNT) fibers were directly spun from a vertically aligned CNT forest grown by a plasma-enhanced chemical vapor deposition (PECVD) process. The correlation of the CNT structure with Fe catalyst coarsening, reaction time, and the CNTs bundling phenomenon was investigated. We controlled the diameters and walls of the CNTs and minimized the amorphous carbon deposition on the CNTs for favorable bundling and spinning of the CNT fibers. The CNT fibers were fabricated with an as-grown vertically aligned CNT forest by a PECVD process using nanocatalyst an Al2O3 buffer layer, followed by a dry spinning process. Well-aligned CNT fibers were successfully manufactured using a dry spinning process and a surface tension-based densification process by ethanol. The mechanical properties were characterized for the CNT fibers spun from different lengths of a vertically aligned CNT forest. Highly oriented CNT fibers from the dry spinning process were characterized with high strength, high modulus, and high electrical as well as thermal conductivities for possible application as ultralight, highly strong structural materials. Examples of structural materials include space elevator cables, artificial muscle, and armor material, while multifunctional materials include E-textile, touch panels, biosensors, and super capacitors.

  4. A generic process of growing aligned carbon nanotube arrays on metals and metal alloys

    International Nuclear Information System (INIS)

    Parthangal, Prahalad M; Cavicchi, Richard E; Zachariah, Michael R

    2007-01-01

    Aligned carbon nanotube (CNT) arrays are integral towards the development of several applications such as field emission, interconnects in silicon technology, and chemical and biological sensing. Even though the synthesis of CNTs has been described extensively in the literature, there has not been significant success in growing uniform, well-aligned CNT arrays on pure metal surfaces other than metals that catalyse CNT growth themselves. In this paper, we describe a method of growing aligned CNT arrays on a variety of pure metals, metal alloys, and conductive ceramics using a bimetallic iron/alumina composite catalyst at low temperatures (550 to 700 deg. C). We believe that the addition of alumina to the iron catalyst significantly reduces catalyst-metal underlayer interactions that have traditionally proven to be a barrier for the growth of CNTs on metals. The alumina also minimizes surface diffusion of iron and allows the formation of a high density of uniformly dispersed catalyst nanoparticles to act as nucleation sites for well-aligned CNT arrays. Despite the presence of non-conducting alumina from the catalyst, the contact resistance between the CNTs and the metal underlayer was observed to be quite low, emphasizing the usefulness of this approach to practical applications. Our process was successful in growing aligned CNTs even on commercial steel plates and may be applicable for substrates of any shape or size

  5. Bioactivity behaviour of nano-hydroxyapatite/freestanding aligned carbon nanotube oxide composite.

    Science.gov (United States)

    Siqueira, Idalia A W B; Oliveira, Ciliana A G S; Zanin, Hudson; Grinet, Marco A V M; Granato, Alessandro E C; Porcionatto, Marimelia A; Marciano, Fernanda R; Lobo, Anderson O

    2015-02-01

    Bioactive and low cytotoxic three dimensional nano-hydroxyapatite (nHAp) and aligned carbon nanotube oxide (a-CNTO) composite has been investigated. First, freestanding aligned carbon nanotubes porous scaffold was prepared by large-scale thermal chemical vapour deposition and functionalized by oxygen plasma treatment, forming a-CNTO. The a-CNTO was covered with plate-like nHAp crystals prepared by in situ electrodeposition techniques, forming nHAp/a-CNTO composite. After that nHAp/a-CNTO composite was immersed in simulated body fluid for composite consolidation. This novel nanobiomaterial promotes mesenchymal stem cell adhesion with the active formation of membrane projections, cell monolayer formation and high cell viability.

  6. Behavior of oxidized platinum nanoparticles on an aligned carbon nanotube forest

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Keita, E-mail: matsuda.keita@c.mbox.nagoya-u.ac.jp; Norimatsu, Wataru [Department of Applied Chemistry, Nagoya University, Nagoya 464-8603 (Japan); Arai, Shigeo; Kusunoki, Michiko [Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8603 (Japan)

    2016-10-14

    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.

  7. 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.

  8. Tritrichomonas foetus adhere to superhydrophilic vertically aligned multi-walled carbon nanotube surface

    International Nuclear Information System (INIS)

    Moreira Machado, Susane; Oliveira Lobo, Anderson; Bueno Loureiro Sapucahy, Ariel; Marciano, Fernanda Roberta; Corat, Evaldo Jose; Soares da Silva, Newton

    2011-01-01

    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: → This is a new method to study the T. foetus adhesion mechanism. → SEM images and interfacial adhesion force show a high adhesion level. → It is very important for future understanding mechanism adhesion and protein expression.

  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. 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.

  11. A one-step technique to prepare aligned arrays of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mahanandia, Pitamber [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Nanda, Karuna Kar [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)], E-mail: pitam@physics.iisc.ernet.in

    2008-04-16

    A simple effective pyrolysis technique has been developed to synthesize aligned arrays of multi-walled carbon nanotubes (MWCNTs) without using any carrier gas in a single-stage furnace at 700 deg. C. This technique eliminates nearly the entire complex and expensive machinery associated with other extensively used methods for preparation of CNTs such as chemical vapour deposition (CVD) and pyrolysis. Carbon source materials such as xylene, cyclohexane, camphor, hexane, toluene, pyridine and benzene have been pyrolyzed separately with the catalyst source material ferrocene to obtain aligned arrays of MWCNTs. The synthesized CNTs have been characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. In this technique, the need for the tedious and time-consuming preparation of metal catalysts and continuously fed carbon source material containing carrier gas can be avoided. This method is a single-step process where not many parameters are required to be monitored in order to prepare aligned MWCNTs. For the production of CNTs, the technique has great advantages such as low cost and easy operation.

  12. Route to sustainable lithium-sulfur batteries with high practical capacity through a fluorine free polysulfide catholyte and self-standing Carbon Nanofiber membranes

    OpenAIRE

    Lim, Du-Hyun; Agostini, Marco; Nitze, Florian; Manuel, James; Ahn, Jou-Hyeon; Matic, Aleksandar

    2017-01-01

    We report on a new strategy to improve the capacity, reduce the manufacturing costs and increase the sustainability of Lithium-Sulfur (LiS) batteries. It is based on a semi-liquid cathode composed of a Li2S8 polysulphide catholyte and a binder-free carbon nanofiber membrane with tailored morphology. The polysulphides in the catholyte have the dual role of active material and providing Li+-conduction, i.e. no traditional Li-salt is used in this cell. The cell is able to deliver an areal capaci...

  13. Facile synthesis of highly aligned multiwalled carbon nanotubes from polymer precursors.

    Energy Technology Data Exchange (ETDEWEB)

    Han, C. Y.; Xiao, Z.-L.; Wang, H. H.; Lin, X.-M.; Trasobares, S.; Cook, R. E.; Richard J. Daley Coll.; Northern Illinois Univ.; Univ. de Cadiz

    2009-01-01

    We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.

  14. Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

    Directory of Open Access Journals (Sweden)

    Catherine Y. Han

    2009-01-01

    Full Text Available We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.

  15. Development and characterization of highly oriented PAN nanofiber

    Directory of Open Access Journals (Sweden)

    M. Sadrjahani

    2010-12-01

    Full Text Available A simple and non-conventional electrospinning technique was employed for producing highly oriented Polyacrylonitrile (PAN nanofibers. The PAN nanofibers were electrospun from 14 wt% solution of PAN in dimethylformamid (DMF at 11 kv on a rotating drum with various linear speeds from 22.5 m/min to 67.7 m/min. The influence of take up velocity was investigated on the degree of alignment, internal structure and mechanical properties of collected PAN nanofibers. Using an image processing technique, the best degree of alignment was obtained for those nanofibers collected at a take up velocity of 59.5 m/min. Moreover, Raman spectroscopy was used for measuring molecular orientation of PAN nanofibers. Similarly, a maximum chain orientation parameter of 0.25 was determined for nanofibers collected at a take up velocity of 59.5 m/min.

  16. Controllable Construction of Core-Shell Polymer@Zeolitic Imidazolate Frameworks Fiber Derived Heteroatom-Doped Carbon Nanofiber Network for Efficient Oxygen Electrocatalysis.

    Science.gov (United States)

    Zhao, Yingxuan; Lai, Qingxue; Zhu, Junjie; Zhong, Jia; Tang, Zeming; Luo, Yan; Liang, Yanyu

    2018-03-26

    Designing rational nanostructures of metal-organic frameworks based carbon materials to promote the bifunctional catalytic activity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desired but still remains a great challenge. Herein, an in situ growth method to achieve 1D structure-controllable zeolitic imidazolate frameworks (ZIFs)/polyacrylonitrile (PAN) core/shell fiber (PAN@ZIFs) is developed. Subsequent pyrolysis of this precursor can obtain a heteroatom-doped carbon nanofiber network as an efficient bifunctional oxygen electrocatalyst. The electrocatalytic performance of derived carbon nanofiber is dominated by the structures of PAN@ZIFs fiber, which is facilely regulated by efficiently controlling the nucleation and growth process of ZIFs on the surface of polymer fiber as well as optimizing the components of ZIFs. Benefiting from the core-shell structures with appropriate dopants and porosity, as-prepared catalysts show brilliant bifunctional ORR/OER catalytic activity and durability. Finally, the rechargeable Zn-air battery assembled from the optimized catalyst (CNF@Zn/CoNC) displays a peak power density of 140.1 mW cm -2 , energy density of 878.9 Wh kg Zn -1 , and excellent cyclic stability over 150 h, giving a promising performance in realistic application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Reverse capillary flow of condensed water through aligned multiwalled carbon nanotubes.

    Science.gov (United States)

    Yun, Jongju; Jeon, Wonjae; Alam Khan, Fakhre; Lee, Jinkee; Baik, Seunghyun

    2015-06-12

    Molecular transport through nanopores has recently received considerable attention as a result of advances in nanofabrication and nanomaterial synthesis technologies. Surprisingly, water transport investigations through carbon nanochannels resulted in two contradicting observations: extremely fast transport or rejection of water molecules. In this paper, we elucidate the mechanism of impeded water vapor transport through the interstitial space of aligned multiwalled carbon nanotubes (aligned-MWCNTs)--capillary condensation, agglomeration, reverse capillary flow, and removal by superhydrophobicity at the tip of the nanotubes. The origin of separation comes from the water's phase change from gas to liquid, followed by reverse capillary flow. First, the saturation water vapor pressure is decreased in a confined space, which is favorable for the phase change of incoming water vapor into liquid drops. Once continuous water meniscus is formed between the nanotubes by the adsoprtion and agglomeration of water molecules, a high reverse Laplace pressure is induced in the mushroom-shaped liquid meniscus at the entry region of the aligned-MWCNTs. The reverse Laplace pressure can be significantly enhanced by decreasing the pore size. Finally, the droplets pushed backward by the reverse Laplace pressure can be removed by superhydrophobicity at the tip of the aligned-MWCNTs. The analytical analysis was also supported by experiments carried out using 4 mm-long aligned-MWCNTs with different intertube distances. The water rejection rate and the separation factor increased as the intertube distance decreased, resulting in 90% and 10, respectively, at an intertube distance of 4 nm. This mechanism and nanotube membrane may be useful for energy-efficient water vapor separation and dehumidification.

  18. 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.

  19. Electrospun Nanofibers: New Concepts, Materials, and Applications.

    Science.gov (United States)

    Xue, Jiajia; Xie, Jingwei; Liu, Wenying; Xia, Younan

    2017-08-15

    Electrospinning is a simple and versatile technique that relies on the electrostatic repulsion between surface charges to continuously draw nanofibers from a viscoelastic fluid. It has been applied to successfully produce nanofibers, with diameters down to tens of nanometers, from a rich variety of materials, including polymers, ceramics, small molecules, and their combinations. In addition to solid nanofibers with a smooth surface, electrospinning has also been adapted to generate nanofibers with a number of secondary structures, including those characterized by a porous, hollow, or core-sheath structure. The surface and/or interior of such nanofibers can be further functionalized with molecular species or nanoparticles during or after an electrospinning process. In addition, electrospun nanofibers can be assembled into ordered arrays or hierarchical structures by manipulation of their alignment, stacking, and/or folding. All of these attributes make electrospun nanofibers well-suited for a broad spectrum of applications, including those related to air filtration, water purification, heterogeneous catalysis, environmental protection, smart textiles, surface coating, energy harvesting/conversion/storage, encapsulation of bioactive species, drug delivery, tissue engineering, and regenerative medicine. Over the past 15 years, our group has extensively explored the use of electrospun nanofibers for a range of applications. Here we mainly focus on two examples: (i) use of ceramic nanofibers as catalytic supports for noble-metal nanoparticles and (ii) exploration of polymeric nanofibers as scaffolding materials for tissue regeneration. Because of their high porosity, high surface area to volume ratio, well-controlled composition, and good thermal stability, nonwoven membranes made of ceramic nanofibers are terrific supports for catalysts based on noble-metal nanoparticles. We have investigated the use of ceramic nanofibers made of various oxides, including SiO 2 , TiO 2

  20. 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.

  1. 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...

  2. 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...

  3. 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.

  4. 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.

  5. 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

  6. Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs

    Directory of Open Access Journals (Sweden)

    Sun HY

    2017-04-01

    Full Text Available Hongyu Sun,* Jing Zhou,* Zhu Huang,* Linlin Qu,* Ning Lin,* Chengxiao Liang, Ruiwu Dai, Lijun Tang, Fuzhou Tian General Surgery Center, Chengdu Military General Hospital, Chengdu, China *These authors contributed equally to this work Abstract: Carbon nanotubes (CNTs provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell–cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt% exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future. Keywords: carbon nanotubes, collagen hydrogel, cardiac constructs, cell alignment, tissue functionality

  7. 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.

  8. Align and random electrospun mat of PEDOT:PSS and PEDOT:PSS/RGO

    Science.gov (United States)

    Sarabi, Ghazale Asghari; Latifi, Masoud; Bagherzadeh, Roohollah

    2018-01-01

    In this research work we fabricated two ultrafine conductive nanofibrous layers to investigate the materilas composition and their properties for the preparation of supercapacitor materials application. In first layer, a polymer and a conductive polymer were used and second layer was a composition of polymer, conductive polymer and carbon-base material. In both cases align and randomized mat of conductive nanofibers were fabricated using electrospinning set up. Conductive poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT:PSS) nanofibers were electrospun by dissolving fiber-forming polymer and polyvinyl alcohol (PVA) in an aqueous dispersion of PEDOT:PSS. The effect of addition of reduced graphene oxide (RGO) was considered for nanocomposite layer. The ultrafine conductive polymer fibers and conductive nanocomposite fibrous materials were also fabricated using an electrospinning process. A fixed collector and a rotating drum were used for random and align nanofibers production, respectively. The resulted fibers were characterized and analyzed by SEM, FTIR and two-point probe conductivity test. The average diameter of nanofibers measured by ImageJ software indicated that the average fiber diameter for first layer was 100 nm and for nanocomposite layer was about 85 nm. The presence of PEDOT:PSS and RGO in the nanofibers was confirmed by FT-IR spectroscopy. The conductivity of align and random layers was characterized. The conductivity of PEDOT:PSS nanofibers showed higher enhancement by addition of RGO in aqueous dispersion. The obtained results showed that alignment of fibrous materials can be considered as an engineering tool for tuning the conductivity of fibrous materials for many different applications such as supercapacitors, conductive and transparent materials.

  9. Hydrogen sorption and permeability of compacted LiBH4 nanoconfined into activated carbon nanofibers impregnated with TiO2

    Science.gov (United States)

    Sitthiwet, Chongsutthamani; Thiangviriya, Sophida; Thaweelap, Natthaporn; Meethom, Sukanya; Kaewsuwan, Dechmongkhon; Chanlek, Narong; Utke, Rapee

    2017-11-01

    Activated carbon nanofibers impregnated with titanium (IV) oxide (TiO2), denoted as ACNF-Ti are prepared by carbonization and activation of electrospun nanofibers of polyacrylonitrile (PAN)-titanium (IV) isopropoxide composite. Pristine LiBH4 and nanoconfined LiBH4 in ACNF-Ti, denoted as LiBH4-ACNF-Ti are compacted under the pressures of 434 and 868 MPa. Dehydrogenation temperature of compacted LiBH4 increases (up to 485 °C) with compaction pressure due to poor hydrogen permeability. In the case of compacted LiBH4-ACNF-Ti, major dehydrogenation temperature at 352-359 °C and hydrogen content liberated (74-76% of theoretical capacity) are obtained despite enhanced compaction pressure. Mechanical stability during cycling of compacted LiBH4-ACNF-Ti is achieved. Although hydrogen permeability of compacted LiBH4-ACNF-Ti improves with enhanced compaction pressure, detrimental kinetics and reversibility are detected. Since the fibrous structure of ACNF-Ti are brittle, the broken and/or shorten fibers are observed after compaction under high pressure. The latter results in not only inferior nanoconfinement of LiBH4 into ACNF-Ti, but also agglomeration of hydride materials upon cycling.

  10. CuO Quantum Dots Embedded in Carbon Nanofibers as Binder-Free Anode for Sodium Ion Batteries with Enhanced Properties.

    Science.gov (United States)

    Wang, Xiaojun; Liu, Yongchang; Wang, Yijing; Jiao, Lifang

    2016-09-01

    The design of sodium ion batteries is proposed based on the use of flexible membrane composed of ultrasmall transition metal oxides. In this paper, the preparation of CuO quantum dots (≈2 nm) delicately embedded in carbon nanofibers (denoted as 2-CuO@C) with a thin film via a feasible electrospinning method is reported. The CuO content can be controlled by altering the synthetic conditions and is optimized to 54 wt%. As binder-free anode for sodium ion batteries, 2-CuO@C delivers an initial reversible capacity of 528 mA h g -1 at the current density of 100 mA g -1 , an exceptional rate capability of 250 mA h g -1 at 5000 mA g -1 , and an ultra-stable capacity of 401 mA h g -1 after 500 cycles at 500 mA g -1 . The enhancement of electrochemical performance is attributed to the unique structure of 2-CuO@C, which offers a variety of advantages: highly conductive carbon matrix suppressing agglomeration of CuO grains, interconnected nanofibers ensuring short transport length for electrons, well-dispersed CuO quantum dots leading to highly utilization rate, and good mechanical properties resulting in strong electrode integrity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

    Science.gov (United States)

    Hao, Xiaodong; Wang, Jie; Ding, Bing; Wang, Ya; Chang, Zhi; Dou, Hui; Zhang, Xiaogang

    2017-06-01

    Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g-1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g-1 at a current density of 0.5 A g-1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

  12. Carbon-free Li4Ti5O12 porous nanofibers as high-rate and ultralong-life anode materials for lithium-ion batteries

    Science.gov (United States)

    Bian, Min; Yang, Yong; Tian, Ling

    2018-02-01

    In this work, the carbon-free Li4Ti5O12 porous nanofibers (Li4Ti5O12-P-NFs) have been successfully fabricated through an electrospinning approach followed by a one-step solid-state reaction. The structural and morphological characterization indicates that the as-prepared Li4Ti5O12-P-NFs has a spinel Li4Ti5O12 phase and many nanosized pores are homogeneously dispersed in the one-dimensional nanofibers. When used as anode material for lithium-ion batteries, the Li4Ti5O12-P-NFs exhibit excellent battery performances in terms of high-rate capability and ultralong-life stability, which can be attributed to the unique carbon-free porous nanostructure composed of well-crystallized Li4Ti5O12 nanocrystals. Thus, we can speculate that this novel concept may also be applicable to prepare other electrode materials for high-performance lithium-ion batteries.

  13. Towards large scale aligned carbon nanotube composites: an industrial safe-by-design and sustainable approach

    International Nuclear Information System (INIS)

    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

    2013-01-01

    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.

  14. Electron-shading effect on the horizontal aligned growth of carbon nanotubes

    International Nuclear Information System (INIS)

    Chai Yang; Xiao Zhiyong; Chan, Philip C. H.

    2009-01-01

    Based on the well-accepted electron-shading theory during plasma processing, we designed microstructures to control the local built-in electric-field on the substrate surface. The distortion magnitude of the electric-field is largest near the sidewalls of the microstructures, creating a horizontal electric-field in this region. We showed that the horizontally aligned carbon nanotubes (CNTs) were grown by making use of this built-in electric-field during the plasma-enhanced chemical vapor deposition process, with a tactical choice of geometries and materials of the microstructures on the substrate. This technique opens up a way to selectively and controllably grow horizontally aligned CNTs on the substrate surface

  15. Angle-dependent light emission from aligned multiwalled carbon nanotubes under CO2 laser irradiation

    International Nuclear Information System (INIS)

    Zhang, Y; Gong, T; Liu, W J; Wei, J Q; Zhang, X F; Wang, K L; Zhong, M L; Wu, D H

    2007-01-01

    This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO 2 laser (λ = 10.6 μm) irradiation. Results indicate that the light emission is dependent on the angle θ between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when θ varies from 0 0 to 90 0 . The Lorentzian fitting curve displays a distinct tendency between shorter (λ 700 nm). A minimum intensity was observed at θ m close to 67 0 under shorter wavelength, whereas a maximum intensity was shown at θ m of about 60 0 at longer wavelength. These results show the anisotropic property of aligned MWNTs

  16. High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guzman de Villoria, R; Hart, A J; Steiner, S A III; Wardle, B L [Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Figueredo, S L; Slocum, A H, E-mail: rguzman@mit.ed [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2009-10-07

    Vertically aligned carbon nanotube (CNT) arrays are grown on a moving substrate, demonstrating continuous growth of nanoscale materials with long-range order. A cold-wall chamber with an oscillating moving platform is used to locally heat a silicon growth substrate coated with an Fe/Al{sub 2}O{sub 3} catalyst film for CNT growth via chemical vapor deposition. The reactant gases are introduced over the substrate through a directed nozzle to attain high-yield CNT growth. Aligned multi-wall carbon nanotube arrays (or 'forests') with heights of {approx}1 mm are achieved at substrate speeds up to 2.4 mm s{sup -1}. Arrays grown on moving substrates at different velocities are studied in order to identify potential physical limitations of repeatable and fast growth on a continuous basis. No significant differences are noted between static and moving growth as characterized by scanning electron microscopy and Raman spectroscopy, although overall growth height is marginally reduced at the highest substrate velocity. CNT arrays produced on moving substrates are also found to be comparable to those produced through well-characterized batch processes consistent with a base-growth mechanism. Growth parameters required for the moving furnace are found to differ only slightly from those used in a comparable batch process; thermal uniformity appears to be the critical parameter for achieving large-area uniform array growth. If the continuous-growth technology is combined with a reaction zone isolation scheme common in other types of processing (e.g., in the manufacture of carbon fibers), large-scale dense and aligned CNT arrays may be efficiently grown and harvested for numerous applications including providing interlayers for advanced composite reinforcement and improved electrical and thermal transport.

  17. Health effects of exposure to carbon nanofibers: Systematic review, critical appraisal, meta analysis and research to practice perspectives

    International Nuclear Information System (INIS)

    Genaidy, Ash; Tolaymat, Thabet; Sequeira, Reynold; Rinder, Magda; Dionysiou, Dion

    2009-01-01

    Background: Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and health consequences are qualitative in nature and do not employ an evidence-based assessment. Objective: This research deals with a systematic review, critical appraisal, and meta-analysis designed to examine the potential health effects associated with exposure to CNFs. The utilization of research findings into practice is also explored. Methods: Published articles were obtained from a search of electronic databases and bibliographies of identified articles. A critical appraisal was conducted using an 'Experimental Appraisal Instrument' developed in this study. The meta-analysis was established using statistical techniques with/without the incorporation of overall study quality. The likelihood of utilizing research findings into practice (i.e., from research to practice) was computed using a four-step algorithm based on the criteria of: strength of association, consistency among studies, temporality, biological gradient, type of experimental unit, type of CNF (single- and multi-wall nanotubes), CNF grade (commercial or altered), exposure dose, exposure duration, and support by analogy from the published literature. Results: Twenty-one experimental studies satisfied the inclusion criteria and were performed on human cells, experimental animal models and animal cells as experimental units. The methodological qualities of published studies ranged from 'very poor' to 'excellent', with 'overall study description' scoring 'good' and 'study execution' equal to 'moderate'. The random-effects model was applied in the meta-analysis calculations as heterogeneity was significant at the 10% for all outcomes reported. The mean standardized meta-estimates for the experimental groups were significantly lower than those for the control groups for cell viability and cell death, respectively. Incorporating the effect of overall study quality score widened the gap between the

  18. 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)

  19. Tailoring the pore alignment for rapid ion transport in microporous carbons.

    Science.gov (United States)

    Kajdos, Adam; Kvit, Alexander; Jones, Frank; Jagiello, Jacek; Yushin, Gleb

    2010-03-17

    The power density and charge-discharge time of electrical double layer capacitors are largely determined by how fast the electrolyte ions can travel within the carbon electrode particles. Our systematic studies using zeolite-templated carbons show that an enhancement in ion transport rate by more than 2 orders of magnitude is possible by minimizing the micropore tortuosity. Very uniform carbon deposition was achieved using a well-controlled process involving the decomposition of acetylene precursor at a reduced pressure of 10 Torr and under a constant flow rate of 100 sccm. Selected carbon samples with well-aligned, straight micropores demonstrate high specific capacitance of up to 300 F/g and outstanding frequency response of up to 10 Hz for 250 microm thick electrodes, indicating an attractive combination of high specific energy and high specific power in electrical double layer capacitors. Such properties are critical for many peak-power hungry applications, such as the leveling of subsecond disturbances in power lines. Our findings provide guidance for the optimal design of porous carbons with greatly improved power storage characteristics.

  20. 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.

  1. 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.

  2. High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

    Directory of Open Access Journals (Sweden)

    Bipin Kumar Gupta

    2018-01-01

    Full Text Available The vertical aligned carbon nanotubes (CNTs-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si wafer substrate at 775 °C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness as a barrier layer and iron (Fe, 1.5 nm thickness as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2–30 walls with an inner diameter of 3–8 nm. Raman spectrum analysis shows G-band at 1580 cm−1 and D-band at 1340 cm−1. The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm2 at 1.2V/μm, low turn-on field (0.6 V/μm and field enhancement factor (6917 with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources.

  3. 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.

  4. Mechanical function near defects in an aligned nanofiber composite is preserved by inclusion of disorganized layers: Insight into meniscus structure and function.

    Science.gov (United States)

    Bansal, Sonia; Mandalapu, Sai; Aeppli, Céline; Qu, Feini; Szczesny, Spencer E; Mauck, Robert L; Zgonis, Miltiadis H

    2017-07-01

    The meniscus is comprised of circumferentially aligned fibers that resist the tensile forces within the meniscus (i.e., hoop stress) that develop during loading of the knee. Although these circumferential fibers are severed by radial meniscal tears, tibial contact stresses do not increase until the tear reaches ∼90% of the meniscus width, suggesting that the severed circumferential fibers still bear load and maintain the mechanical functionality of the meniscus. Recent data demonstrates that the interfibrillar matrix can transfer strain energy to disconnected fibrils in tendon fascicles. In the meniscus, interdigitating radial tie fibers, which function to stabilize and bind the circumferential fibers together, are hypothesized to function in a similar manner by transmitting load to severed circumferential fibers near a radial tear. To test this hypothesis, we developed an engineered fibrous analog of the knee meniscus using poly(ε-caprolactone) to create aligned scaffolds with variable amounts of non-aligned elements embedded within the scaffold. We show that the tensile properties of these scaffolds are a function of the ratio of aligned to non-aligned elements, and change in a predictable fashion following a simple mixture model. When measuring the loss of mechanical function in scaffolds with a radial tear, compared to intact scaffolds, the decrease in apparent linear modulus was reduced in scaffolds containing non-aligned layers compared to purely aligned scaffolds. Increased strains in areas adjacent to the defect were also noted in composite scaffolds. These findings indicate that non-aligned (disorganized) elements interspersed within an aligned network can improve overall mechanical function by promoting strain transfer to nearby disconnected fibers. This finding supports the notion that radial tie fibers may similarly promote tear tolerance in the knee meniscus, and will direct changes in clinical practice and provide guidance for tissue engineering

  5. Vertically Aligned Carbon Nanotube Array (VANTA Biosensor for MEMS Lab-on-a-Chip

    Directory of Open Access Journals (Sweden)

    Luke JOSEPH

    2009-10-01

    Full Text Available We describe the fabrication, functionalization and characterization of vertically aligned carbon nanotube arrays (VANTAs for biological sensor applications. This structure is created using a standard MEMS process and chemical vapor deposition (CVD multi-walled carbon nanotube (MWNT post-processing. The device is well suited for full integration into microfluidic lab-on-a-chip solutions. Included is a spectroscopic characterization of the galvanostatic impedance of the device, as well as scanning electron microscopy (SEM images of the pre- and post- functionalized device. Interferometric 3D profiling and X-ray spectroscopy were also used to check process assumptions. The work presented validates that this approach is an ideal candidate for low-cost, high-throughput manufacturing of biochemical sensors. Unlike previously published work [1, 2] using SWNT, the use of MWNT arrays allows functionalization over the entirety of the nanotubes. This approach maintains low baseline impedance and increases the surface area leveraging inherent benefits of the VANTA.

  6. 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.

  7. Heat transport in electrically aligned multiwalled carbon nanotubes dispersed in water

    Science.gov (United States)

    Cervantes-Alvarez, F.; Macias, J. D.; Alvarado-Gil, J. J.

    2018-02-01

    A modified Ångström method was used to determine the thermal diffusivity and thermal conductivity of aqueous dispersions of multiwalled carbon nanotubes as a function of their weight fraction concentration and in the presence of an externally applied electric field. Measurements were performed in planar samples, with a fixed thickness of 3.18 mm applying an AC voltage in the range from 0 to 70~V_RMS and for concentrations of carbon nanotubes from 0 to 2 wf%. It is shown that this field induces the formation of clusters followed by their alignment along the electric field, which can favor heat transfer in that direction. Heat transfer measurements show two regimes, in the first one under 0.5 wf%, voltages lower than 30~V_RMS are not strong enough to induce the adequate order of the carbon nanostructures, and as a consequence, thermal diffusivity of the dispersion remains close to the thermal diffusivity of water. In contrast for higher concentrations (above 1.5 wf%), 10~V_RMS are enough to get a good alignment. Above such thresholds of concentrations and voltages, thermal diffusivity and conductivity increase, when the electric field is increased, in such a way that for an applied voltage of 20~V_RMS and for a concentration of 1.5 wf%, an increase of 49% of the thermal conductivity was obtained. It is also shown that this approach exhibits limits, due to the fact that the electric-field induced structure, can act as a heating element at high electric field intensities and carbon nanotubes concentrations, which can induce convection and evaporation of the liquid matrix.

  8. Alignment of carbon nanotubes and reinforcing effects in nylon-6 polymer composite fibers

    Science.gov (United States)

    Rangari, Vijaya K.; Yousuf, Mohammed; Jeelani, Shaik; Pulikkathara, Merlyn X.; Khabashesku, Valery N.

    2008-06-01

    Alignment of pristine carbon nanotubes (P-CNTs) and fluorinated carbon nanotubes (F-CNTs) in nylon-6 polymer composite fibers (PCFs) has been achieved using a single-screw extrusion method. CNTs have been used as filler reinforcements to enhance the mechanical and thermal properties of nylon-6 composite fibers. The composites were fabricated by dry mixing nylon-6 polymer powder with the CNTs as the first step, then followed by the melt extrusion process of fiber materials in a single-screw extruder. The extruded fibers were stretched to their maxima and stabilized using a godet set-up. Finally, fibers were wound on a Wayne filament winder machine and tested for their tensile and thermal properties. The tests have shown a remarkable change in mechanical and thermal properties of nylon-6 polymer fibers with the addition of 0.5 wt% F-CNTs and 1.0 wt% of P-CNTs. To draw a comparison between the improvements achieved, the same process has been repeated with neat nylon-6 polymer. As a result, tensile strength has been increased by 230% for PCFs made with 0.5% F-CNTs and 1% P-CNTs as additives. These fibers have been further characterized by DSC, Raman spectroscopy and SEM which confirm the alignment of CNTs and interfacial bonding to nylon-6 polymer matrix.

  9. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Li, Kuan-Wei [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Honda, Shin-ichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Lin, Pao-Hung; Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2017-06-01

    Graphical abstract: The pattern design provides a new structure of surface-conduction electron-emitter display (SED). Delta-star shaped vertically aligned CNT (VACNT) arrays with 20o tips can simultaneously provide three emitters to bombard the sides of equilateral triangles pattern of VACNT, which produces numerous secondary electrons and enhance the SED efficiency. - Highlights: • The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. • The vertically aligned CNT (VACNT) arrays with 20° tips of the delta-star arrangement are used as cathodes that easily emit electrons. The cathode pattern simultaneously provides three emitters to bombard the sides of equilateral triangles pattern of VACNT. • The VACNT arrays were covered with magnesium oxide (MgO) nanostructures to promote the surface-conduction electron-emitter display (SED) efficiency (η). • The η was stably maintained in the 75–85% range. The proposed design provides a facile new method for developing SED applications. - Abstract: The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75–85% range. The proposed design provides a facile new method for

  10. Crystallization of Poly(3-hexylthiophene Nanofiber in a Narrow Groove

    Directory of Open Access Journals (Sweden)

    Satoshi Kushi

    2016-06-01

    Full Text Available Whisker-type poly(3-hexylthiophene-2,5-diyl (P3HT nanofibers were aligned by restricting their growth direction using an approximately 100–1000 nm wide narrow groove fabricated by thermal nanoimprinting. In grooves made of an amorphous fluoropolymer (CYTOP™ with widths of less than 1500 nm, the nanofibers oriented uniaxially perpendicular to the groove and their length was limited to the width of the groove. This result indicates that the nucleation of nanofibers tends to be selectively promoted near the interface of CYTOP™ with fluoro-groups, and nanofiber growth perpendicular to the wall is promoted because P3HT molecules are supplied more frequently from the center of the groove. Furthermore, the orientation induced anisotropic conductivity, and the conductivity parallel to the oriented nanofibers was more than an order of magnitude higher than that perpendicular to the oriented nanofibers.

  11. Ultralight super-hydrophobic carbon aerogels based on cellulose nanofibers/poly(vinyl alcohol)/graphene oxide (CNFs/PVA/GO) for highly effective oil–water separation

    Science.gov (United States)

    Zhou, Huan; Tan, Sicong; Jiang, Xiangdong; Wu, Weibing; Shi, Jiangtao; Chen, Peng

    2018-01-01

    With the worsening of the oil-product pollution problem, oil–water separation has attracted increased attention in recent years. In this study, a porous three-dimensional (3D) carbon aerogel based on cellulose nanofibers (CNFs), poly(vinyl alcohol) (PVA) and graphene oxide (GO) was synthesized by a facile and green approach. The resulting CNF/PVA/GO aerogels were synthesized through an environmentally friendly freeze-drying process and then carbonized to yield CNF/PVA/GO carbon aerogels with low density (18.41 mg cm−3), high porosity (98.98%), a water contact angle of 156° (super-hydrophobic) and high oil absorption capacity (97 times its own weight). The carbonization treatment of the CNF/PVA/GO aerogel not only improved the hydrophobic properties but also enhanced the adsorption capacity and specific surface area. Given the many good performance characteristics and the facile preparation process of carbon aerogels, these materials are viable candidates for use in oil–water separation and environmental protection. PMID:29527428

  12. Influence of synthesis parameters on CCVD growth of vertically aligned carbon nanotubes over aluminum substrate.

    Science.gov (United States)

    Szabó, Anna; Kecsenovity, Egon; Pápa, Zsuzsanna; Gyulavári, Tamás; Németh, Krisztián; Horvath, Endre; Hernadi, Klara

    2017-08-25

    In the past two decades, important results have been achieved in the field of carbon nanotube (CNT) research, which revealed that carbon nanotubes have extremely good electrical and mechanical properties The range of applications widens more, if CNTs form a forest-like, vertically aligned structure (VACNT) Although, VACNT-conductive substrate structure could be very advantageous for various applications, to produce proper system without barrier films i.e. with good electrical contact is still a challenge. The aim of the current work is to develop a cheap and easy method for growing carbon nanotubes forests on conductive substrate with the CCVD (Catalytic Chemical Vapor Deposition) technique at 640 °C. The applied catalyst contained Fe and Co and was deposited via dip coating onto an aluminum substrate. In order to control the height of CNT forest several parameters were varied during the both catalyst layer fabrication (e.g. ink concentration, ink composition, dipping speed) and the CCVD synthesis (e.g. gas feeds, reaction time). As-prepared CNT forests were investigated with various methods such as scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry. With such an easy process it was possible to tune both the height and the quality of carbon nanotube forests.

  13. 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. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Dielectrophoretically aligned carbon nanotubes to control electrical and mechanical properties of hydrogels to fabricate contractile muscle myofibers.

    Science.gov (United States)

    Ramón-Azcón, Javier; Ahadian, Samad; Estili, Mehdi; Liang, Xiaobin; Ostrovidov, Serge; Kaji, Hirokazu; Shiku, Hitoshi; Ramalingam, Murugan; Nakajima, Ken; Sakka, Yoshio; Khademhosseini, Ali; Matsue, Tomokazu

    2013-08-07

    Dielectrophoresis is used to align carbon nanotubes (CNTs) within gelatin methacrylate (GelMA) hydrogels in a facile and rapid manner. Aligned GelMA-CNT hydrogels show higher electrical properties compared with pristine and randomly distributed CNTs in GelMA hydrogels. The muscle cells cultured on these materials demonstrate higher maturation compared with cells cultured on pristine and randomly distributed CNTs in GelMA hydrogels. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

    Science.gov (United States)

    Li, Bing; Ge, Xiaoming; Goh, F. W. Thomas; Hor, T. S. Andy; Geng, Dongsheng; Du, Guojun; Liu, Zhaolin; Zhang, Jie; Liu, Xiaogang; Zong, Yun

    2015-01-01

    An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm-2) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization

  16. 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.

  17. Facile preparation of efficient electrocatalysts for oxygen reduction reaction: One-dimensional meso/macroporous cobalt and nitrogen Co-doped carbon nanofibers

    Science.gov (United States)

    Yoon, Ki Ro; Choi, Jinho; Cho, Su-Ho; Jung, Ji-Won; Kim, Chanhoon; Cheong, Jun Young; Kim, Il-Doo

    2018-03-01

    Efficient electrocatalyst for oxygen reduction reaction (ORR) is an essential component for stable operation of various sustainable energy conversion and storage systems such as fuel cells and metal-air batteries. Herein, we report a facile preparation of meso/macroporous Co and N co-doped carbon nanofibers (Co-Nx@CNFs) as a high performance and cost-effective electrocatalyst toward ORR. Co-Nx@CNFs are simply obtained from electrospinning of Co precursor and bicomponent polymers (PVP/PAN) followed by temperature controlled carbonization and further activation step. The prepared Co-Nx@CNF catalyst carbonized at 700 °C (Co-Nx@CNF700) shows outstanding ORR performance, i.e., a low onset potential (0.941 V) and half wave potential (0.814 V) with almost four-electron transfer pathways (n= 3.9). In addition, Co-Nx@CNF700 exhibits a superior methanol tolerance and higher stability (>70 h) in Zn-air battery in comparison with Pt/C catalyst (∼30 h). The outstanding performance of Co-Nx@CNF700 catalysts is attributed to i) enlarged surface area with bimodal porosity achieved by leaching of inactive species, ii) increase of exposed ORR active Co-Nx moieties and graphitic edge sites, and iii) enhanced electrical conductivity and corrosion resistance due to the existence of numerous graphitic flakes in carbon matrix.

  18. Preparation and Properties of Flexible AZO@C Nanofibers

    Directory of Open Access Journals (Sweden)

    MA Hui

    2018-01-01

    Full Text Available A new type of environmental-friendly flexible nanofibers of aluminum doped zinc oxide (AZO coated carbon (AZO@C was successfully prepared by using polyvinyl alcohol (PVA as raw materials. The as-spun PVA nanofibers were prepared via electrospinning and its water resistance was greatly improved after heat-treatment. Then, the PVA nanofibers with a layer of zinc aluminum hydroxide on the surface were synthesized by hydrothermal method. Thereafter, new AZO@C composite nanofibers was produced after sintering at 500℃ to the carbonization of PVA nanofibers and the dehydration of zinc aluminum hydroxide to form AZO nanoparticles. The structure and properties of the samples were characterized by Fourier-transform infrared spectrometer (FT-IR, thermal gravimetric analyzer (TGA and scanning electron microscope (SEM. The average diameter of the AZO@C nanofibers is (320±45nm. The photocatalytic property of the resultant composite fibers is demonstrated by degrading methyl orange under solar light.

  19. Aligned carbon nanotube webs as a replacement for indium tin oxide in organic solar cells

    International Nuclear Information System (INIS)

    Sears, Kallista; Fanchini, Giovanni; Watkins, Scott E.; Huynh, Chi P.; Hawkins, Stephen C.

    2013-01-01

    Bulk heterojunction solar cells were fabricated with flexible webs of aligned multiwalled carbon nanotubes (MWNTs). These webs were drawn from a forest of MWNTs and placed directly onto the device substrate to form the hole collecting electrode. Devices were fabricated on glass substrates with one or two MWNT web layers to study the trade-off between transparency and resistivity on device performance. Devices with two web layers performed better with a fill factor of 0.47 and a device power conversion efficiency of 1.66% due to their higher conductivity. Flexible devices on Mylar substrates were also demonstrated with an efficiency of 1.2% indicating the potential of MWNT webs as a flexible alternative to the more conventional indium tin oxide. - Highlights: ► Drawable carbon nanotube webs were used as an anode in bulk heterojunction cells. ► One and two layers of carbon nanotube webs were compared. ► A thick active layer of ∼ 530 nm was needed to avoid shunting through nanotubes. ► Two layers of web gave the better efficiency of 1.6%. ► Flexible devices on Mylar were demonstrated with 1.2% efficiency

  20. 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.

  1. Liquid-phase synthesis of vertically aligned carbon nanotubes and related nanomaterials on preheated alloy substrates

    Science.gov (United States)

    Yamagiwa, Kiyofumi

    2018-02-01

    Carbon nanotubes (CNTs) and related nanocarbons were selectively synthesized on commercially available alloy substrates by a simple liquid-phase technique. Fe- and Ni-rich stainless-steel (JIS SUS316L and Inconel®600, respectively) and Ni–Cu alloy (Monel®400) substrates were used for the synthesis, and each substrate was preheated in air to promote the self-formation of catalyst nanolayers on the surface. The substrates were resistance heated in ethanol without any addition of catalysts to grow CNTs. The yield of the CNTs effectively increased when the preheating process was employed. Highly aligned CNT arrays grew on the SUS316L substrate, while non-aligned CNTs and distinctive twisted fibers were observed on the other substrates. An Fe oxide layer was selectively formed on the preheated SUS316L substrate promoting the growth of the CNT arrays. Characterizations including cyclic voltammetry for the arrays revealed that the CNTs possess a comparatively defect-rich surface, which is a desirable characteristic for its application such as electrode materials for capacitors.

  2. Effect of alignment on adsorption characteristics of self-oriented multi-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Zilli, D; Bonelli, P R; Cukierman, A L

    2006-01-01

    The adsorption characteristics of self-oriented multi-walled carbon nanotube (MWCNT) arrays are examined from N 2 (-196 deg. C) adsorption measurements. The arrays were synthesized in a laboratory by in situ chemical vapour deposition of iron or cobalt phthalocyanines at 880 and 950 deg. C, under otherwise constant conditions, in an attempt to obtain different morphological structures. For both precursors, increasing the temperature leads to MWCNT arrays with lower Brunauer-Emmett-Teller (BET) surface area and total pore volume, though the effect is more pronounced for those arising from the iron-based compound. Despite this, precursor yields of individual nanotubes of larger diameter, higher BET area and total pore volume characterize the resulting arrays compared to those arising from cobalt phthalocyanine for the same temperatures. As evidenced by SEM and TEM images, the arrays synthesized from iron phthalocyanine at 880 deg. C show better vertical alignment and denser structures than those obtained from this compound at 950 deg. C, and also from cobalt phthalocyanine at both temperatures. Further ultrasonication of the arrays produced from the iron compound brings about a significant reduction in their adsorption capacity, attributable to the pronounced disarrangement of the resulting structures. The present results demonstrate that the alignment of MWCNT arrays plays a crucial role in their N 2 adsorption characteristics

  3. Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring in civil engineering.

    Science.gov (United States)

    Lebental, B; Chainais, P; Chenevier, P; Chevalier, N; Delevoye, E; Fabbri, J-M; Nicoletti, S; Renaux, P; Ghis, A

    2011-09-30

    Structural health monitoring of porous materials such as concrete is becoming a major component in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large numbers within a porous material in order to provide information on its durability by monitoring in situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration over a large range of frequencies spanning from 100 kHz to 5 MHz.

  4. Synthesis of Vertically Aligned Carbon Nanotubes on Silicalite-1 Monolayer-Supported Substrate

    Directory of Open Access Journals (Sweden)

    Wei Zhao

    2014-01-01

    Full Text Available Monodisperse magnetic Fe3O4 nanoparticles (NPs with the size of ca. 3.5 nm were prepared and used as the catalysts for the synthesis of vertically aligned carbon nanotube (VACNT arrays. A silicalite-1 microcrystal monolayer was used as the support layer between catalyst NPs and the silicon substrate. Compared to our previous report which used radio-frequency- (rf- sputtered Fe2O3 film as the catalyst, Fe3O4 NPs that were synthesized by wet chemical method showed an improved catalytic ability with less agglomeration. The silicalite-1 crystal monolayer acted as an effective “buffer” layer to prevent the catalyst NPs from agglomerating during the reaction process. It is believed that this is the first report that realizes the vertical alignment of CNTs over the zeolite monolayer, namely, silicalite-1 microcrystal monolayer, instead of using the intermediate anodic aluminum oxide (AAO scaffold to regulate the growth direction of CNT products.

  5. Effect of alignment on adsorption characteristics of self-oriented multi-walled carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zilli, D [Programa de Investigacion y Desarrollo de Fuentes Alternativas de Materias Primas y EnergIa (PINMATE)-Depto. de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Int. Gueiraldes 2620, Ciudad Universitaria (C1428BGA), Buenos Aires (Argentina); Bonelli, P R [Programa de Investigacion y Desarrollo de Fuentes Alternativas de Materias Primas y EnergIa (PINMATE)-Depto. de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Int. Gueiraldes 2620, Ciudad Universitaria (C1428BGA), Buenos Aires (Argentina); Cukierman, A L [Programa de Investigacion y Desarrollo de Fuentes Alternativas de Materias Primas y EnergIa (PINMATE)-Depto. de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Int. Gueiraldes 2620, Ciudad Universitaria (C1428BGA), Buenos Aires (Argentina)

    2006-10-28

    The adsorption characteristics of self-oriented multi-walled carbon nanotube (MWCNT) arrays are examined from N{sub 2} (-196 deg. C) adsorption measurements. The arrays were synthesized in a laboratory by in situ chemical vapour deposition of iron or cobalt phthalocyanines at 880 and 950 deg. C, under otherwise constant conditions, in an attempt to obtain different morphological structures. For both precursors, increasing the temperature leads to MWCNT arrays with lower Brunauer-Emmett-Teller (BET) surface area and total pore volume, though the effect is more pronounced for those arising from the iron-based compound. Despite this, precursor yields of individual nanotubes of larger diameter, higher BET area and total pore volume characterize the resulting arrays compared to those arising from cobalt phthalocyanine for the same temperatures. As evidenced by SEM and TEM images, the arrays synthesized from iron phthalocyanine at 880 deg. C show better vertical alignment and denser structures than those obtained from this compound at 950 deg. C, and also from cobalt phthalocyanine at both temperatures. Further ultrasonication of the arrays produced from the iron compound brings about a significant reduction in their adsorption capacity, attributable to the pronounced disarrangement of the resulting structures. The present results demonstrate that the alignment of MWCNT arrays plays a crucial role in their N{sub 2} adsorption characteristics.

  6. Compressive response and deformation mechanisms of vertically aligned helical carbon nanotube forests

    Science.gov (United States)

    Scheffer, V. C.; Thevamaran, R.; Coluci, V. R.

    2018-01-01

    We study the dynamic compressive response of vertically aligned helical carbon nanotube forests using a mesoscale model. To describe the compressive response, the model includes the helical geometry of the constituent coils, the entanglement between neighboring coils, and the sideway interactions among coils. Coarse-grained simulations show forest densification and stress localization, which are caused by different deformation mechanisms such as coil packing, buckling, and crushing. We find that these mechanisms depend on the initial overlap between coils and lead to a nonlinear stress-strain behavior that agrees with recent impact experiments. The nonlinear stress-strain behavior was shown to be composed of an initial linear increase of stress in strain followed by an exponential growth. These regimes are an outcome of the characteristics of both the individual coils and the entangled morphology of the forests.

  7. Controlled density of vertically aligned carbon nanotubes in a triode plasma chemical vapor deposition system

    International Nuclear Information System (INIS)

    Lim, Sung Hoon; Park, Kyu Chang; Moon, Jong Hyun; Yoon, Hyun Sik; Pribat, Didier; Bonnassieux, Yvan; Jang, Jin

    2006-01-01

    We report on the growth mechanism and density control of vertically aligned carbon nanotubes using a triode plasma enhanced chemical vapor deposition system. The deposition reactor was designed in order to allow the intermediate mesh electrode to be biased independently from the ground and power electrodes. The CNTs grown with a mesh bias of + 300 V show a density of ∼ 1.5 μm -2 and a height of ∼ 5 μm. However, CNTs do not grow when the mesh electrode is biased to - 300 V. The growth of CNTs can be controlled by the mesh electrode bias which in turn controls the plasma density and ion flux on the sample

  8. High-performance supercapacitors using a nanoporous current collector made from super-aligned carbon nanotubes.

    Science.gov (United States)

    Zhou, Ruifeng; Meng, Chuizhou; Zhu, Feng; Li, Qunqing; Liu, Changhong; Fan, Shoushan; Jiang, Kaili

    2010-08-27

    Nanoporous current collectors for supercapacitors have been fabricated by cross-stacking super-aligned carbon nanotube (SACNT) films as a replacement for heavy conventional metallic current collectors. The CNT-film current collectors have good conductivity, extremely low density (27 microg cm(-2)), high specific surface area, excellent flexibility and good electrochemical stability. Nanosized active materials such as NiO, Co(3)O(4) or Mn(2)O(3) nanoparticles can be directly synthesized on the SACNT films by a straightforward one-step, in situ decomposition strategy that is both efficient and environmentally friendly. These composite films can be integrated into a pseudo-capacitor that does not use metallic current collectors, but nevertheless shows very good performance, including high specific capacitance (approximately 500 F g(-1), including the current collector mass), reliable electrochemical stability (<4.5% degradation in 2500 cycles) and a very high rate capability (245 F g(-1) at 155 A g(-1)).

  9. Dry-Transfer of Aligned Multi walled Carbon Nano tubes for Flexible Transparent Thin Films

    International Nuclear Information System (INIS)

    Cole, M.; Ying, K.; Zhang, Y.; Ferrari, A.; Hiralal, P.; Chi, L.; Milne, W.; Teo, K.

    2012-01-01

    Herein we present an inexpensive facile wet-chemistry-free approach to the transfer of chemical vapour-deposited multi walled carbon nano tubes to flexible transparent polymer substrates in a single-step process. By controlling the nano tube length, we demonstrate accurate control over the electrical conductivity and optical transparency of the transferred thin films. Uniaxial strains of up to 140% induced only minor reductions in sample conductivity, opening up a number of applications in stretchable electronics. Nano tube alignment offers enhanced functionality for applications such as polarisation selective electrodes and flexible super capacitor substrates. A capacitance of 17 F/g was determined for super capacitors fabricated from the reported dry-transferred MWCNTs with the corresponding cyclic volta grams showing a clear dependence on nano tube length.

  10. Proposed model for biomineralization of novel nanohydroxyapatite/vertically aligned multiwalled carbon nanotube scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Brazil, Tayra Rodrigues; Neves, Marcele Florencio das; Marciano, Fernanda Roberta; Lobo, Anderson Oliveira, E-mail: aolobo@univap.br [Universidade do Vale do Paraiba (UniVap), Sao Jose dos Campos, SP (Brazil). Lab. de Nanotecnologia Biomedica; Regiani, Inacio [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil)

    2013-11-01

    For the first time, the growth mechanism of biominerals formed on plate-like nanohydroxyapatite (nHAp) electrodeposited on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O{sub 2} ) is presented and a model for the specific growth preference is discussed. VAMWCNT-O{sub 2} films were obtained by microwave-assisted chemical vapor deposition method and functionalized by oxygen plasma. nHAp/VAMWCNT-O{sub 2} nanocomposites were fabricated with a direct electrodeposition of the thin nHAp films onto the VAMWCNT-O{sub 2} films. The biomineralized 'scaffolds' were obtained by soaking nHAp/VAMWCNT-O{sub 2} in simulated body fluid for 7, 14 and 21 days. Results show that the carboxyl functional groups directly attached onto VAMWCNT tips after oxygen plasma treatment were essential for the acceleration of the OH- formation and the deposition of plate-like nHAp crystals (author)

  11. Effects of interfaces on nano-friction of vertically aligned multi-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Lou, J.; Kim, K.-S.

    2008-01-01

    Sliding friction properties of vertically aligned multi-walled carbon nanotube (VAMWNT) arrays have been investigated in current study in a quantitative manner. The VAMWNT arrays have been fabricated on an anodic aluminum oxide template by chemical vapor deposition at 650 deg. C. Friction force was measured in air by a modified atomic force microscopy (AFM) cantilever-bead assembly with 15 μm diameter borosilicate sphere attached to the end of the regular AFM cantilever. Quantitative measurements were achieved by using a novel in situ calibration methods recently developed based on diamagnetic levitation [Q. Li, K.-S. Kim, A. Rydberg, Rev. Sci. Instrum. 77 (2006) 065105-1-13]. The effects of different interfaces were studied using both cantilever-bead assembly coated with and without Al thin layer coatings. A reverse stick-slip behavior was observed in the current system as compared to the normal stick-slip behavior found in the literature

  12. Calcification in vitro of Biomineralized nanohydroxyapatite / superhydrophilic vertically aligned multiwalled carbon nanotube scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Marcele Florencio; Silva, Gislene Rodrigues; Brazil, Tayra Rodrigues; Marciano, Fernanda Roberta; Lobo, Anderson Oliveira, E-mail: loboao@yahoo.com, E-mail: aolobo@univap.br [Universidade do Vale do Paraiba (UniVap), Sao Jose dos Campos, SP (Brazil). Lab. de Nanotecnologia Biomedica; Pacheco-Soares, Cristina [Universidade do Vale do Paraiba (UniVap), Sao Jose dos Campos, SP (Brazil). Lab. de Dinamica de Compartimentos Celulares

    2013-11-01

    Nanocomposites based on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O{sub 2}) and nanohydroxyapatite (nHAp) are of great interest in bone regenerative medicine. The biomineralization using simulated body fluid (SBF) has been extensively studied to evaluate the bioactivity of biomaterials. Thus, the combination of nHAp and VAMWCNT-O{sub 2} is attractive and promising. The aim of this study was to evaluate the in vitro calcification of nHAp/VAMWCNT-O{sub 2} nanocomposites before and after the period of biomineralization in SBF. In vitro calcification of the extracellular matrix (ECM) of HOB cells in culture after 24 hours was investigated through the assay of alkaline phosphatase. These promising in vitro results validate biomineralized nHAp/VAMWCNT-O{sub 2} as possible scaffolds for bone tissue regeneration. (author)

  13. Effect of iron catalyst thickness on vertically aligned carbon nanotube forest straightness for CNT-MEMS

    International Nuclear Information System (INIS)

    Moulton, Kellen; Jensen, Brian D; Morrill, Nicholas B; Konneker, Adam M; Vanfleet, Richard R; Allred, David D; Davis, Robert C

    2012-01-01

    This paper examines the effect of iron catalyst thickness on the straightness of growth of carbon nanotubes (CNTs) for microelectromechanical systems fabricated using the CNT-templated-microfabrication (CNT-M) process. SEM images of samples grown using various iron catalyst thicknesses show that both straight sidewalls and good edge definition are achieved using an iron thickness between 7 and 8 nm. Below this thickness, individual CNTs are well aligned, but the sidewalls of CNT forests formed into posts and long walls are not always straight. Above this thickness, the CNT forest sidewalls are relatively straight, but edge definition is poor, with significantly increased sidewall roughness. The proximity of a device or feature to other regions of iron catalyst also affects CNT growth. By using an iron catalyst thickness appropriate for straight growth, and by adding borders of iron around features or devices, a designer can greatly improve straightness of growth for CNT-MEMS. (paper)

  14. Calcification in vitro of biomineralizated nanohydroxyapatite/superydrophilic vertically aligned multiwalled carbon nanotube scaffolds

    Directory of Open Access Journals (Sweden)

    Marcele Florencio Neves

    2013-06-01

    Full Text Available Nanocomposites based on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O2 and nanohydroxyapatite (nHAp are of great interest in bone regenerative medicine. The biomineralization using simulated body fluid (SBF has been extensively studied to evaluate the bioactivity of biomaterials. Thus, the combination of nHAp and VAMWCNT-O2 is attractive and promising. The aim of this study was to evaluate the in vitro calcification of nHAp/VAMWCNT-O2 nanocomposites before and after the period of biomineralization in SBF. In vitro calcification of the extracellular matrix (ECM of HOB cells in culture after 24 hours was investigated through the assay of alkaline phosphatase. These promising in vitro results validate biomineralized nHAp/VAMWCNT-O2 as possible scaffolds for bone tissue regeneration.

  15. Electrospun Nanofibers of Guar Galactomannan for Targeted Drug Delivery

    Science.gov (United States)

    Chu, Hsiao Mei Annie

    2011-12-01

    Guar galactomannan is a biodegradable polysaccharide used widely in the food industry but also in the cosmetics, pharmaceutical, oil drilling, textile and paper industries. Guar consists of a mannose backbone and galactose side groups that are both susceptible to enzyme degradation, a unique property that can be explored for targeted drug delivery especially since those enzymes are naturally secreted by the microflora in human colon. The present study can be divided into three parts. In the first part, we discuss ways to modify guar to produce nanofibers by electrospinning, a process that involves the application of an electric field to a polymer solution or melt to facilitate production of fibers in the sub-micron range. Nanofibers are currently being explored as the next generation of drug carriers due to its many advantages, none more important than the fact that nanofibers are on a size scale that is a fraction of a hair's width and have large surface-to-volume ratio. The incorporation and controlled release of nano-sized drugs is one way in which nanofibers are being utilized in drug delivery. In the second part of the study, we explore various methods to crosslink guar nanofibers as a means to promote water-resistance in a potential drug carrier. The scope and utility of water-resistant guar nanofibers can only be fully appreciated when subsequent drug release studies are carried out. To that end, the third part of our study focuses on understanding the kinetics and diffusion mechanisms of a model drug, Rhodamine B, through moderately-swelling (crosslinked) hydrogel nanofibers in comparison to rapidly-swelling (non-crosslinked) nanofibers. Along the way, our investigations led us to a novel electrospinning set-up that has a unique collector designed to capture aligned nanofibers. These aligned nanofiber bundles can then be twisted to hold them together like yarn. From a practical standpoint, these yarns are advantageous because they come freely suspended and

  16. Cobalt Nanoparticle-Embedded Porous Carbon Nanofibers with Inherent N- and F-Doping as Binder-Free Bifunctional Catalysts for Oxygen Reduction and Evolution Reactions.

    Science.gov (United States)

    Singhal, Richa; Kalra, Vibha

    2017-01-18

    Efficient, low-cost, non-precious metal-based, and stable bifunctional electrocatalysts are key to various energy storage and conversion devices such as regenerative fuel cells and metal-air batteries. In this work, we report cobalt nanoparticle-embedded porous carbon nanofibers with inherent N- and F-doping as binder-free bifunctional electrocatalysts with excellent activity for both the oxygen reduction and oxygen evolution reaction (ORR/OER) in an alkaline medium. Single-step electrospinning of a solution of the polymer mixture (carbon precursor) and the cobalt precursor followed by controlled pyrolysis with an intermediate reduction step in H 2 (to reduce cobalt oxides to cobalt) was utilized to synthesize an integrated freestanding catalyst. The fabricated catalyst with effective structural and electronic interaction between the cobalt metal nanoparticles and the N- and F-doped carbon defect sites showed enhanced catalytic properties compared to the benchmark catalysts for ORR and OER (Pt, Ir, and Ru). The ORR potential at the current density of -3 mA cm -2 was 0.81 V RHE and the OER potential at a current density of 10 mA cm -2 was 1.595 V RHE , resulting in a ΔE of only 0.785 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Electrospinning Hetero-Nanofibers of Fe3 C-Mo2 C/Nitrogen-Doped-Carbon as Efficient Electrocatalysts for Hydrogen Evolution.

    Science.gov (United States)

    Lin, Huanlei; Zhang, Wenbiao; Shi, Zhangping; Che, Minwei; Yu, Xiang; Tang, Yi; Gao, Qingsheng

    2017-06-22

    Heterostructured electrocatalysts with multiple active components are expected to synchronously address the two elementary steps in the hydrogen evolution reaction (HER), which require varied hydrogen-binding strength on the catalyst surface. Herein, electrospinning followed by a pyrolysis is introduced to design Fe 3 C-Mo 2 C/nitrogen-doped carbon (Fe 3 C-Mo 2 C/NC) hetero-nanofibers (HNFs) with tunable composition, leading to abundant Fe 3 C-Mo 2 C hetero-interfaces for synergy in electrocatalysis. Owing to the strong hydrogen binding on Mo 2 C and the relatively weak one on Fe 3 C, the hetero-interfaces of Fe 3 C-Mo 2 C remarkably promote HER kinetics and intrinsic activity. Additionally, the loose and porous N-doped carbon matrix, as a result of Fe-catalyzed carbonization, ensures the fast transport of electrolytes and electrons, thus minimizing diffusion limitation. As expected, the optimized Fe 3 C-Mo 2 C/NC HNFs afforded a low overpotential of 116 mV at a current density of -10 mA cm -2 and striking kinetics metrics (onset overpotential: 42 mV, Tafel slope: 43 mV dec -1 ) in 0.5 m H 2 SO 4 , outperforming most recently reported noble-metal-free electrocatalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Fast preparation of PtRu catalysts supported on carbon nanofibers by the microwave-polyol method and their application to fuel cells.

    Science.gov (United States)

    Tsuji, Masaharu; Kubokawa, Masatoshi; Yano, Ryuto; Miyamae, Nobuhiro; Tsuji, Takeshi; Jun, Mun-Suk; Hong, Seonghwa; Lim, Seongyop; Yoon, Seong-Ho; Mochida, Isao

    2007-01-16

    PtRu alloy nanoparticles (24 +/- 1 wt %, Ru/Pt atomic ratios = 0.91-0.97) supported on carbon nanofibers (CNFs) were prepared within a few minutes by using a microwave-polyol method. Three types of CNFs with very different surface structures, such as platelet, herringbone, and tubular ones, were used as new carbon supports. The dependence of particles sizes and electrochemical properties on the structures of CNFs was examined. It was found that the methanol fuel cell activities of PtRu/CNF catalysts were in the order of platelet > tubular > herringbone. The methanol fuel cell activities of PtRu/CNFs measured at 60 degrees C were 1.7-3.0 times higher than that of a standard PtRu (29 wt %, Ru/Pt atomic ratio = 0.92) catalyst loaded on carbon black (Vulcan XC72R) support. The best electrocatalytic activity was obtained for the platelet CNF, which is characterized by its edge surface and high graphitization degree.

  19. Field emission from a composite structure consisting of vertically aligned single-walled carbon nanotubes and carbon nanocones

    International Nuclear Information System (INIS)

    Yeh, C M; Chen, M Y; Hwang, J; Gan, J-Y; Kou, C S

    2006-01-01

    Vertically aligned single-walled carbon nanotubes (VA-SWCNTs) have been fabricated on carbon nanocones (CNCs) in a gravity-assisted chemical vapour deposition (CVD) process. The CNCs with nanoscale Co particles at the top were first grown on the Co/Si(100) substrate biased at 350 V in a plasma enhanced chemical vapour deposition process. The CNCs typically are ∼200 nm in height, and their diameters are ∼100 nm near the bottom and ∼10 nm at the top. The nanoscale Co particles ∼10 nm in diameter act as catalysts which favour the growth of VA-SWCNTs out of CNCs at 850 0 C in the gravity-assisted CVD process. The average length and the growth time of VA-SWCNTs are ∼150 nm and 1.5 min, equivalent to a growth rate of ∼6 μm h -1 . The diameters of VA-SWCNTs are estimated to be 1.2-2.1 nm. When VA-SWCNTs are fabricated on CNCs, the turn-on voltage is reduced from 3.9 to 0.7 V μm -1 and the emission current density at the electric field of 5 V μm -1 is enhanced by a factor of more than 200. The composite VA-SWCNT/CNC structure is potentially an excellent field emitter. The emission stability of the VA-SWCNT/CNC field emitter is discussed

  20. Multidimensional MnO2 nanohair-decorated hybrid multichannel carbon nanofiber as an electrode material for high-performance supercapacitors

    Science.gov (United States)

    Jun, Jaemoon; Lee, Jun Seop; Shin, Dong Hoon; Kim, Sung Gun; Jang, Jyongsik

    2015-09-01

    One-dimensional (1D)-structured nanomaterials represent one of the most attractive candidates for energy-storage systems due to their contribution to design simplicity, fast charge-transportation network, and their allowance for more accessible ion diffusion. In particular, 1D-structured nanomaterials with a highly complex inner-pore configuration enhance functionality by taking advantage of both the hollow and 1D structures. In this study, we report a MnO2 nanohair-decorated, hybrid multichannel carbon nanofiber (Mn_MCNF) fabricated via single-nozzle co-electrospinning of two immiscible polymer solutions, followed by carbonization and redox reactions. With improved ion accessibility, the optimized Mn_MCNF sample (Mn_MCNF_60 corresponding to a reaction duration time of 60 min for optimal MnO2 nanohair growth) exhibited a high specific capacitance of 855 F g-1 and excellent cycling performance with ~87.3% capacitance retention over 5000 cycles.One-dimensional (1D)-structured nanomaterials represent one of the most attractive candidates for energy-storage systems due to their contribution to design simplicity, fast charge-transportation network, and their allowance for more accessible ion diffusion. In particular, 1D-structured nanomaterials with a highly complex inner-pore configuration enhance functionality by taking advantage of both the hollow and 1D structures. In this study, we report a MnO2 nanohair-decorated, hybrid multichannel carbon nanofiber (Mn_MCNF) fabricated via single-nozzle co-electrospinning of two immiscible polymer solutions, followed by carbonization and redox reactions. With improved ion accessibility, the optimized Mn_MCNF sample (Mn_MCNF_60 corresponding to a reaction duration time of 60 min for optimal MnO2 nanohair growth) exhibited a high specific capacitance of 855 F g-1 and excellent cycling performance with ~87.3% capacitance retention over 5000 cycles. Electronic supplementary information (ESI) available: Experimental data includes

  1. Reduced graphene oxide and vertically aligned carbon nanotubes superhydrophilic films for supercapacitors devices

    Energy Technology Data Exchange (ETDEWEB)

    Zanin, H., E-mail: hudsonzanin@gmail.com [Associated Laboratory of Sensors and Materials of the National Institute for Space Research, Av. dos Astronautas 1758, Sao Jose dos Campos CEP 12227-010, SP (Brazil); Departamento de Semicondutores, Instrumentos e Fotônica, Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas, UNICAMP, Campinas 13083-970 (Brazil); Saito, E., E-mail: esaito135@gmail.com [Associated Laboratory of Sensors and Materials of the National Institute for Space Research, Av. dos Astronautas 1758, Sao Jose dos Campos CEP 12227-010, SP (Brazil); Ceragioli, H.J., E-mail: helderjc@gmail.com [Departamento de Semicondutores, Instrumentos e Fotônica, Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas, UNICAMP, Campinas 13083-970 (Brazil); Baranauskas, V., E-mail: vitor@dsif.fee.unicamp.br [Departamento de Semicondutores, Instrumentos e Fotônica, Faculdade de Engenharia Elétrica e Computação, Universidade Estadual de Campinas, UNICAMP, Campinas 13083-970 (Brazil); Corat, E.J., E-mail: corat@las.inpe.br [Associated Laboratory of Sensors and Materials of the National Institute for Space Research, Av. dos Astronautas 1758, Sao Jose dos Campos CEP 12227-010, SP (Brazil)

    2014-01-01

    Graphical abstract: - Highlights: • Graphene nanosheets were produced onto wire rods. • RGO and VACNT-O were evaluated and compared as supercapacitor electrode. • RGO and VACNT-O have structural and electrochemical properties quite similars. • The materials present good specific capacitance, energy storage and power delivery. - Abstract: Reduced graphene oxide (RGO) and vertically aligned carbon nanotubes (VACNT) superhydrophilic films were prepared by chemical vapor deposition techniques for electrical energy storage investigations. These electrodes were characterized in terms of their material and electrochemical properties by scanning electron microscopy (SEM), surface wettability, Fourier transform infrared spectroscopy (FTIR), energy dispersive and Raman spectroscopies, cyclic voltammetry (CV) and galvanostatic charge–discharge. We observed several physical structural and electrochemical similarities between these carbon-based materials with particular attention to very good specific capacitance, ultra-high energy storage and fast power delivery. Our results showed that the main difference between specific capacitance values is attributed to pseudocapacitive contribution and high density of multiwall nanotubes tips. In this work we have tested a supercapacitor device using the VACNT electrodes.

  2. Graphene—vertically aligned carbon nanotube hybrid on PDMS as stretchable electrodes

    Science.gov (United States)

    Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric; Lee, Woo; Fisher, Frank T.; Yang, Eui-Hyeok

    2017-11-01

    Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO)-VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition. VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386 ± 55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications.

  3. Scalable synthesis of aligned carbon nanotubes bundles using green natural precursor: neem oil

    Directory of Open Access Journals (Sweden)

    Kumar Rajesh

    2011-01-01

    Full Text Available Abstract Practical application of aligned carbon nanotubes (ACNTs would have to be determined by a matter of its economical and large-scale preparation. In this study, neem oil (also named Margoaa oil, extracted from the seeds of the neem--Azadirachta indica was used as carbon source to fabricate the bundles of ACNTs. ACNTs have been synthesized by spray pyrolysis of neem oil and ferrocene mixture at 825°C. The major components of neem oil are hydrocarbon with less amount of oxygen, which provided the precursor species in spray pyrolysis growth of CNTs. The bundles of ACNTs have been grown directly inside the quartz tube. The as-grown ACNTs have been characterized through Raman spectroscopy, scanning and transmission electron microscopic (SEM/TEM techniques. SEM images reveal that the bundles of ACNTs are densely packed and are of several microns in length. High-resolution TEM analysis reveals these nanotubes to be multi-walled CNTs. These multi-walled CNTs were found to have inner diameter between 15 and 30 nm. It was found that present technique gives high yield with high density of bundles of ACNTs.

  4. Synthesis, structural, and field electron emission properties of quasi-aligned carbon nanotubes from gutter oil

    International Nuclear Information System (INIS)

    Suriani, A.B.; Dalila, A.R.; Mohamed, A.; Soga, T.; Tanemura, M.

    2015-01-01

    Quasi-aligned carbon nanotubes (CNTs) have been successfully synthesised from the simple pyrolysis of gutter oil as starting material and ferrocene as a catalyst. The synthesis process was performed at synthesis and vaporisation temperatures of 800 and 250 °C, respectively, in a thermal chemical vapour deposition furnace. The CNTs synthesised using gutter oil have an overall diameter of about 30–50 nm, length of 30 μm, I D /I G ratio of 0.66, and purity of 81%, comparable to those obtained using conventional carbon sources. A field electron emission study of the CNTs exhibited a low turn-on and threshold field of 1.94 and 2.94 V μm −1 , which corresponded to current densities of 100 μA cm −2 and 1.0 mA cm −2 , respectively which indicate that the CNTs synthesised are suitable candidates for use as field electron emitters. The synthesised CNTs from gutter oil also open up potential mass production applications in energy storage devices. This study demonstrates that gutter oil, a low-cost and readily available resource, can be used as an inexpensive carbon source for the mass production of CNTs. - Highlights: • Gutter oil was used as starting material to synthesise CNTs by TCVD method. • CNTs of good quality (I D /I G  ∼ 0.66 and purity ∼ 81%) were successfully produced. • The synthesised CNTs show a potential for field electron emission application.

  5. Study on the Electrospun CNTs/Polyacrylonitrile-Based Nanofiber Composites

    Directory of Open Access Journals (Sweden)

    Bo Qiao

    2011-01-01

    Full Text Available CNTs/PAN nanofibers were electrospun from PAN-based solution for the preparation of carbon nanofiber composites. The as-spun polyacrylonitrile-based nanofibers were hot-stretched by weighing metal in a temperature controlled oven. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to characterize the morphology of the nanofibers, which indicated that carbon nanotubes were dispersed well in the composites and were completely wrapped by PAN matrix. Because of the strong interfacial interaction between CNTs and PAN, the CNTs/PAN application performance will be enhanced correspondingly, such as the mechanical properties and the electrical conductivity. It was concluded that the hot-stretched CNTs/PAN nanofibers can be used as a potential precursor to produce high-performance carbon composites.

  6. Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors.

    Science.gov (United States)

    Li, Pengfei; Martin, Caleb M; Yeung, Kan Kan; Xue, Wei

    2011-01-31

    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 deposit and align in desired locations. The device fabrication is inexpensive, solution-based, and conducted at room temperature. The devices are used as pH sensors with the electrodes as the testing pads and the dielectrophoretically captured SWNTs as the sensing elements. When exposed to aqueous solutions with various pH values, the SWNTs change their resistance accordingly. The SWNT-based sensors demonstrate a linear relationship between the sensor resistance and the pH values in the range of 5-9. The characterization of multiple sensors proves that their pH sensitivity is highly repeatable. The real-time data acquisition shows that the sensor response time depends on the pH value, ranging from 2.26 s for the pH-5 solution to 23.82 s for the pH-9 solution. The long-term stability tests illustrate that the sensors can maintain their original sensitivity for a long period of time. The simple fabrication process, high sensitivity, and fast response of the