WorldWideScience

Sample records for aligned carbon nanofiber

  1. Purification process for vertically aligned carbon nanofibers

    Science.gov (United States)

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

    2003-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-01

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

  3. Study on glow discharge effects on catalyst films for growing aligned carbon nanofibers in negative bias-enhanced hot filament chemical vapor deposition system

    International Nuclear Information System (INIS)

    Aligned carbon nanofibers (ACNFs) were grown on silicon substrates coated with NiFe catalyst films by negative bias-enhanced hot filament chemical vapor deposition (CVD). The growth and structure of the aligned carbon nanofibers were investigated by scanning electron microscopy (SEM). The results indicate that the aligned carbon nanofibers could be synthesized after the glow discharge appears when the negative bias is higher than a certain value, while they are bent if the glow discharge does not appear. Furthermore, the diameters of the aligned carbon nanofibers are reduced and their lengths are increased with increasing the negative bias. It is shown that the glow discharge resulting from the negative bias plays an important role in the growth of aligned carbon nanofibers. Here, the effects of the glow discharge on the growth and structure of the aligned carbon nanofibers are discussed

  4. 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.

  5. Synthesis of vertically aligned carbon nanofibers-carbon nanowalls by plasma-enhanced chemical vapor deposition.

    Science.gov (United States)

    Okamoto, Atsuto; Tanaka, Kei; Yoshimura, Masamichi; Ueda, Kazuyuki; Ghosh, Pradip; Tanemura, Masaki

    2013-03-01

    Vertically aligned carbon nanofibers (VA-CNFs)-carbon nanowalls (CNWs) have been prepared on a silicon (Si) substrate by plasma-enhanced chemical vapor deposition. The VA-CNFs-CNWs were formed at bias voltage of - 185 V, whereas conventional VA-CNFs were synthesized under conditions of high bias voltages. Degenerated CNWs with turbostratic graphite structure were created on amorphous carbon layer around CNFs like a flag attached to a pole, which is evidenced by scanning electron microscopy, transmission electron microscopy, electron diffraction, and micro-Raman spectroscopy. Electron field emission characteristics of VA-CNFs-CNWs with unique microstructure, fabricated on the Si substrate, were primarily investigated. As a result, the VA-CNFs-CNWs showed the turn-on and the threshold fields of 1.7 V x microm(-1) and 3.35 V x microm(-1) with current densities of 10 nA x cm(-2) and 1 microA x cm(-2), respectively. The field enhancement factor beta was estimated to be 1059 by using Fowler-Nordheim theory. PMID:23755628

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

    Directory of Open Access Journals (Sweden)

    Asiri AM

    2014-12-01

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

  7. Growth of carbon nanofibers on aligned zinc oxide nanorods and their field emission properties

    International Nuclear Information System (INIS)

    Carbon nanofibers were grown by electrodeposition technique onto aligned zinc oxide (ZnO) nanorods deposited by hybrid wet chemical route on glass substrates. X-ray diffraction traces indicated very strong peak for reflections from (0 0 2) planes of ZnO. The Raman spectra were dominated by the presence of G band at about 1597 cm-1 corresponding to the E2g tangential stretching mode of an ordered graphitic structure with sp2 hybridization and a D band at about 1350 cm-1 originating from disordered carbon. Fourier transformed infrared studies indicated the presence of a distinct characteristic absorption peak at ∼511 cm-1 for Zn-O stretching mode. Photoluminescence spectra indicated band edge luminescence of ZnO at ∼3.146 eV along with a low intensity peak at ∼0.877 eV arising out of carbon nanofibers. Field emission properties of these films and their dependence on the CNF coverage on ZnO nanorods are reported here. The average field enhancement factor as determined from the slope of the FN plot was found to vary between 1 x 103 and 3 x 103. Both the values of turn-on field and threshold field for CNF/ZnO were lower than pure ZnO nanorods.

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

    Science.gov (United States)

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

    2016-08-01

    This paper reports a linear, low power, and compact CMOS based potentiostat for vertically aligned carbon nanofibers (VACNF) based amperometric glucose sensors. The CMOS based potentiostat consists of a single-ended potential control unit, a low noise common gate difference-differential pair transimpedance amplifier and a low power VCO. The potentiostat current measuring unit can detect electrochemical current ranging from 500 nA to 7 [Formula: see text] from the VACNF working electrodes with high degree of linearity. This current corresponds to a range of glucose, which depends on the fiber forest density. The potentiostat consumes 71.7 [Formula: see text] of power from a 1.8 V supply and occupies 0.017 [Formula: see text] of chip area realized in a 0.18 [Formula: see text] standard CMOS process. PMID:27337723

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

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

  10. Synthesis and properties of SiNx coatings as stable fluorescent markers on vertically aligned carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Ryan Pearce

    2014-04-01

    Full Text Available The growth of vertically aligned carbon nanofibers (VACNFs in a catalytic dc ammonia/acetylene plasma process on silicon substrates is often accompanied by sidewall deposition of material that contains predominantly Si and N. In fluorescent microscopy experiments, whereby VACNFs are interfaced to cell and tissue cultures for a variety of applications, it was observed that this material is broadly fluorescent. In this paper, we provide insight into nature of these silicon/nitrogen in-situ coatings. We propose a potential mechanism for deposition of SiNx coating on the sidewalls of VACNFs during PECVD synthesis and explore the origin of the coating's fluorescence. It is most likely that the substrate reacts with process gases similar to reactive sputtering and chemical vapor deposition (CVD, forming silane and other silicon bearing compounds prior to isotropic deposition as a SiNx coating onto the VACNFs. The formation of Sinanoclusters (NCs is also implicated due to a combination of strong fluorescence and elemental analysis of the samples. These broadly luminescent fibers can prove useful as registry markers in fluorescent cellular studies and for tagging and tracing applications.

  11. 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

  12. Novel continuous carbon and ceramic nanofibers and nanocomposites

    Science.gov (United States)

    Wen, Yongkui

    2004-12-01

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

  13. The Differentiation of Human Endometrial Stem Cells into Neuron-Like Cells on Electrospun PAN-Derived Carbon Nanofibers with Random and Aligned Topographies.

    Science.gov (United States)

    Mirzaei, Esmaeil; Ai, Jafar; Ebrahimi-Barough, Somayeh; Verdi, Javad; Ghanbari, Hossein; Faridi-Majidi, Reza

    2016-09-01

    Electrospun carbon nanofibers (CNFs) have great potential for applications in neural tissue regeneration due to their electrical conductivity, biocompatibility, and morphological similarity to natural extracellular matrix. In this study, we cultured human endometrial stem cells (hEnSCs) on electrospun CNFs with random and aligned topographies and demonstrated that hEnSCs could attach, proliferate, and differentiate into neural cells on both random and aligned CNFs. However, the proliferation, differentiation, and morphology of cells were affected by CNF morphology. Under the proliferative condition, hEnSCs showed lower proliferation on aligned CNFs than on random CNFs and on tissue culture plate (TCP) control. When cultured on aligned CNFs in neural induction media, hEnSCs showed significant upregulation of neuronal markers, NF-H and Tuj-1, and downregulation of neural progenitor marker (nestin) compared to that on random CNFs and on TCP. In contrast, hEnSCs showed higher expression of nestin and slight upregulation of oligodendrocyte marker (OLIG-2) on random CNFs compared to that on aligned CNFs and on TCP. SEM imaging revealed that differentiated cells extended along the CNF main axis on aligned CNFs but stretched multidirectionally on random CNFs. These findings suggest electrospun CNFs as proper substrate for stem cell differentiation into specific neural cells. PMID:26334615

  14. Shear adhesion strength of aligned electrospun nanofibers.

    Science.gov (United States)

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

    2014-09-01

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

  15. Shear adhesion strength of aligned electrospun nanofibers.

    Science.gov (United States)

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

    2014-09-01

    Inspiration from nature such as insects' foot hairs motivates scientists to fabricate nanoscale cylindrical solids that allow tens of millions of contact points per unit area with material substrates. In this paper, we present a simple yet robust method for fabricating directionally sensitive shear adhesive laminates. By using aligned electrospun nylon-6, we create dry adhesives, as a succession of our previous work on measuring adhesion energies between two single free-standing electrospun polymer fibers in cross-cylinder geometry, randomly oriented membranes and substrate, and peel forces between aligned fibers and substrate. The synthetic aligned cylindrical solids in this study are electrically insulating and show a maximal Mode II shear adhesion strength of 27 N/cm(2) on a glass slide. This measured value, for the purpose of comparison, is 270% of that reported from gecko feet. The Mode II shear adhesion strength, based on a commonly known "dead-weight" test, is 97-fold greater than the Mode I (normal) adhesion strength of the same. The data indicate a strong shear binding on and easy normal lifting off. Anisotropic adhesion (Mode II/Mode I) is pronounced. The size and surface boundary effects, crystallinity, and bending stiffness of fibers are used to understand these electrospun nanofibers, which vastly differ from otherwise known adhesive technologies. The anisotropic strength distribution is attributed to a decreasing fiber diameter and an optimized laminate thickness, which, in turn, influences the bending stiffness and solid-state "wettability" of points of contact between nanofibers and surface asperities. PMID:25105533

  16. A novel approach for preparation of aligned electrospun polyacrylonitrile nanofibers

    Science.gov (United States)

    Heidari, Iman; Mosavi Mashhadi, Mahmoud; Faraji, Ghader

    2013-12-01

    In this Letter, a new type of collector named ‘rotating grid collector’ was introduced and its capability in aligning the nanofibers was examined. The results showed that electrospinning using rotating grid collector could produce well aligned fibers with fiber alignment percent of 76%. It was found that in a constant solution flow rate increasing collector rotation speed and eccentric distance improved the fiber alignments. Having prepared the fiber textiles, we found that increasing the rotation speed improved the tensile strength of the fiber textile. This new collector is promising for future application in aligning nanofibers.

  17. 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.

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

    Science.gov (United States)

    Hwang, Wontae; Pang, Changhyun; Chae, Heeyeop

    2016-10-28

    Aligned nanofiber arrays and mats were fabricated with an electrospinning process by manipulating the electric field. The electric field was modified by insulating blocks (IBs) that were installed between the nozzle and the substrate as guiding elements to control the trajectory of the electrospinning jet flow. Simulation results showed that the electric field was deformed near the IBs, resulting in confinement of the electrospinning jet between the blocks. The balance of the electric field in the vertical direction and the repulsive force by space charges in the confined electrified jet stream was attributed to the aligned motion of the jet. Aligned arrays of 200 nm thick polyethylene oxide nanofibers were obtained, exhibiting wave-shaped and cross patterns as well as rectilinear patterns. In addition, 40 μm thick quasi-aligned carbon-nanofiber mats with anisotropic electrical property were also attained by this method. PMID:27651316

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

    Science.gov (United States)

    Hwang, Wontae; Pang, Changhyun; Chae, Heeyeop

    2016-10-01

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

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

    OpenAIRE

    Susobhan Das; Jun Li; Rongqing Hui

    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 ...

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

    Science.gov (United States)

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

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

  2. 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.

  3. Nanofiber alignment of a small diameter elastic electrospun scaffold

    Science.gov (United States)

    Patel, Jignesh

    Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data

  4. Horizontal carbon nanotube alignment.

    Science.gov (United States)

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

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

    Directory of Open Access Journals (Sweden)

    Cheng Jin

    2008-01-01

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

  6. Nanotextured gold coatings on carbon nanofiber scaffolds as ultrahigh surface-area electrodes

    OpenAIRE

    COLAVITA, PAULA

    2012-01-01

    PUBLISHED High surface area metal electrodes are desirable for applications in energy storage and energy conversion. Here, the formation and electrochemical characterization of a hybrid material made by electroless deposition of gold onto a scaffolding of vertically aligned carbon nanofibers is described. Vertically aligned carbon nanofibers, ~80 nm in diameter, provided mechanical support and electrical contact to the highly textured nanoscale gold coatings. By chemically functionalizing ...

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

    Science.gov (United States)

    McClendon, Mark Trosper

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

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

    Science.gov (United States)

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

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

  9. 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.

  10. 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. PMID:27455732

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

    Science.gov (United States)

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

    2014-10-14

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

  12. Focal adhesion kinase regulation in stem cell alignment and spreading on nanofibers.

    Science.gov (United States)

    Andalib, Mohammad Nahid; Lee, Jeong Soon; Ha, Ligyeom; Dzenis, Yuris; Lim, Jung Yul

    2016-05-13

    While electrospun nanofibers have demonstrated the potential for novel tissue engineering scaffolds, very little is known about the molecular mechanism of how cells sense and adapt to nanofibers. Here, we revealed the role of focal adhesion kinase (FAK), one of the key molecular sensors in the focal adhesion complex, in regulating mesenchymal stem cell (MSC) shaping on nanofibers. We produced uniaxially aligned and randomly distributed nanofibers from poly(l-lactic acid) to have the same diameters (about 130 nm) and evaluated MSC behavior on these nanofibers comparing with that on flat PLLA control. C3H10T1/2 murine MSCs exhibited upregulations in FAK expression and phosphorylation (pY397) on nanofibrous cultures as assessed by immunoblotting, and this trend was even greater on aligned nanofibers. MSCs showed significantly elongated and well-spread morphologies on aligned and random nanofibers, respectively. In the presence of FAK silencing via small hairpin RNA (shRNA), cell elongation length in the aligned nanofiber direction (cell major axis length) was significantly decreased, while cells still showed preferred orientation along the aligned nanofibers. On random nanofibers, MSCs with FAK-shRNA showed impaired cell spreading resulting in smaller cell area and higher circularity. Our study provides new data on how MSCs shape their morphologies on aligned and random nanofibrous cultures potentially via FAK-mediated mechanism. PMID:27040763

  13. Carbon Nanofiber Nanoelectrodes for Biosensing Applications

    Science.gov (United States)

    Koehne, Jessica Erin

    2014-01-01

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

  14. Selective adhesion and mineral deposition by osteoblasts on carbon nanofiber patterns

    OpenAIRE

    Khang, Dongwoo; Sato, Michiko; Price, Rachel L.; Ribbe, Alexander E; Webster, Thomas J

    2006-01-01

    In an effort to develop better orthopedic implants, osteoblast (bone-forming cells) adhesion was determined on microscale patterns (30 μm lines) of carbon nanofibers placed on polymer substrates. Patterns of carbon nanofibers (CNFs) on a model polymer (polycarbonate urethane [PCU]) were developed using an imprinting method that placed CNFs in selected regions. Results showed the selective adhesion and alignment of osteoblasts on CNF patterns placed on PCU. Results also showed greater attracti...

  15. Morphology and internal structure of polymeric and carbon nanofibers

    Science.gov (United States)

    Zhong, Zhenxin

    Evaporation and the associated solidification are important factors that affect the diameter of electrospun nanofibers. The evaporation and solidification of a charged jet were controlled by varying the partial pressure of water vapor during electrospinning of poly(ethylene oxide) from aqueous solution. As the partial pressure of water vapor increases, the solidification process of the charged jet becomes slower, allowing elongation of the charged jet to continue longer and thereby to form thinner fibers. The morphology and internal structure of electrospun poly(vinylidene fluorides) nanofibers were investigated. Low voltage high resolution scanning electron microscopy was used to study the surface of electrospun nanofibers. Control of electrospinning process produced fibers with various morphological forms. Fibers that were beaded, branched, or split were obtained when different instabilities dominated in the electrospinning process. The high ratio of stretching during electrospinning aligns the polymer molecules along the fiber axis. A rapid evaporation of solvent during electrospinning gives fibers with small and imperfect crystallites. These can be perfected by thermal annealing. Fibers annealed at elevated temperature form plate-like lamellar crystals tightly linked by tie molecules. Electrospinning can provide ultrafine nanofibers with cross-sections that contain only a few polymer molecules. Ultrafine polymer nanofibers are extremely stable in transmission electron microscope. Electrospun nanofibers suspended on a holey carbon film showed features of individual polymer molecules. Carbon fibers with diameters ranging from 100 nm to several microns were produced from mesophase pitch by a low cost gas jet process. The structure of mesophase pitch-based carbon fibers was investigated as a function of heat treatment temperatures. Submicron-sized graphene oxide flakes were prepared by a combination of oxidative treatment and ultrasonic radiation. Because pitch is

  16. Flexible and Conducting Carbon Nanofibers Obtained from Electrospun Polyacrylonitrile/Phosphoric Acid Nanofibers.

    Science.gov (United States)

    Lim, Baek Ho; Nirmala, R; Navamathavan, R; Kim, Hak Yong

    2016-01-01

    We report on the feasible synthesis of flexible and conductive carbon nanofibers by electrospinning process using polyacrylonitrile (PAN) and phosphoric acid (PA) as precursors. The carbon nanofibers were subsequently obtained by stabilization and carbonization of the electrospun PAN nanofibers. From SEM data, it was found that the electrospun PAN nanofibers showed a smooth surface and had an average diameter of approximately 200 nm. Afterwards, the electrospun PAN nanofibers were stabilized at 250 °C and heated at 900 °C for the carbonization process to obtain the carbon nanofibers. The carbonized PAN nanofibers exhibited a drastic improvement of electrical conduction. From Raman spectroscopy data, it was found that the carbonization at 900 °C gave a decrease of the intensity ratio of D and G peaks, indicating higher graphitic structure. PMID:27398565

  17. Polarized fluorescent emission from aligned electrospun nanofiber sheets containing semiconductor nanorods

    Science.gov (United States)

    Hasegawa, Masaki; Hirayama, Yuki; Dertinger, Stephan

    2015-02-01

    We fabricated sheets consisting of aligned electrospun polymer nanofibers embedded with semiconductor nanorods (NRs) and confirmed the production of polarized fluorescence emission. Electrospun nanofibers with embedded semiconductor NRs were rolled around a drum to form a sheet in which each nanofiber was aligned parallel to the rotation direction. The thickness and polarization ratio of the sheet were 1.5 μm and 0.6, respectively. We also examined how electrospinning parameters affected the polarization ratio of the sheet.

  18. Oriented growth of rat Schwann cells on aligned electrospun poly(methyl methacrylate) nanofibers.

    Science.gov (United States)

    Xia, Haijian; Sun, Xiaochuan; Liu, Dan; Zhou, Yudong; Zhong, Dong

    2016-10-15

    Transplanted Schwann cells have the potential to serve as a support for regenerating neurites after spinal cord injury. However, implanted Schwann cells die off rapidly once transplanted partly owing to the absence of a proper matrix support, with a glia scar and a cavity being present instead at the injury site. For this report, we evaluated aligned electrospun poly(methyl methacrylate) nanofibers as a Schwann cell-loading scaffold in vitro. By monitoring the fluorescence of green fluorescence protein-containing Schwann cells cultured on nanofibers, we found that aligned nanofibers provided better support for the cells than did non-aligned nanofibers. The cells elongated along the long axes of the aligned nanofibers and formed longer cell processes than when the substrate was non-aligned nanofibers. By coculturing Schwann cells with dorsal root ganglion neurons, it was also found that Schwann cells and neurites of dorsal root ganglion neurons could share and both elongate along the orientation of aligned nanofibers and thus they had a higher chance of colocalization than cocultured on film and non-aligned fibers, which might be beneficial to the ensuring process of myelination. The results of the study indicate that aligned electrospun nanofibers may serve as a Schwann cell-loading scaffold for future implantation research. PMID:27653871

  19. Carbon nanofibers: catalytic synthesis and applications

    NARCIS (Netherlands)

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

    2001-01-01

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

  20. Carbon nanofiber growth on thin rhodium layers

    NARCIS (Netherlands)

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

    2012-01-01

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

  1. Dielectric transition of polyacrylonitrile derived carbon nanofibers

    Science.gov (United States)

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

    2014-09-01

    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.

  2. Ellipsometric investigations of photonic crystals based on carbon nanofibers

    CERN Document Server

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

    2010-01-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  4. 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.

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

    Science.gov (United States)

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

    2016-02-01

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

  6. Zinc oxide nanorod assisted rapid single-step process for the conversion of electrospun poly(acrylonitrile) nanofibers to carbon nanofibers with a high graphitic content

    Science.gov (United States)

    Nain, Ratyakshi; Singh, Dhirendra; Jassal, Manjeet; Agrawal, Ashwini K.

    2016-02-01

    The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for immobilization of polymer chains and assisted in uniform heat distribution. This facilitated rapid and efficient conversion of the polymer structure to the ladder, and subsequently, the graphitized structure. At the end of the process, the ZnO nanorods were found to completely separate from the carbonized fibers yielding pure carbon nanofibers with a high graphitic content and surface area. The approach could be used to eliminate the slow, energy intensive stabilization step and achieve fast conversion of randomly laid carbon nanofiber webs in a single step to carbon nanofibers without the application of external tension or internal templates usually employed to achieve a high graphitic content in such systems.The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for

  7. Synthesis of carbon nanofibers on copper particles

    Science.gov (United States)

    Kol'tsova, T. S.; Larionova, T. V.; Shusharina, N. N.; Tolochko, O. V.

    2015-08-01

    We analyze the synthesis of carbon nanostructures from the gas phase (mixture of acetylene or ethylene with hydrogen) on the surface of copper particles without using other catalysts. The synthesized structures (multilayer graphene and carbon nanofibers) are analyzed by transmission electron microscopy and Raman scattering. It is shown that the fiber structure is determined by the C: H ratio in the gas phase. The kinetics of synthesis is analyzed in terms of the formal kinetics of conversion in accordance with the Johnson—Mehl—Avrami equation.

  8. Functionalization of carbon nanotube and nanofiber electrodes with biological macromolecules: Progress toward a nanoscale biosensor

    Science.gov (United States)

    Baker, Sarah E.

    The integration of nanoscale carbon-based electrodes with biological recognition and electrical detection promises unparalleled biological detection systems. First, biologically modified carbon-based materials have been shown to have superior long-term chemical stability when compared to other commonly used materials for biological detection such as silicon, gold, and glass surfaces. Functionalizing carbon electrodes for biological recognition and using electrochemical methods to transduce biological binding information will enable real-time, hand-held, lower cost and stable biosensing devices. Nanoscale carbon-based electrodes allow the additional capability of fabricating devices with high densities of sensing elements, enabling multi-analyte detection on a single chip. We have worked toward the integration of these sensor components by first focusing on developing and characterizing the chemistry required to functionalize single-walled carbon nanotubes and vertically aligned carbon nanofibers with oligonucleotides and proteins for specific biological recognition. Chemical, photochemical and electrochemical methods for functionalizing these materials with biological molecules were developed. We determined, using fluorescence and colorimetric techniques, that these biologically modified nanoscale carbon electrodes are biologically active, selective, and stable. A photochemical functionalization method enabled facile functionalization of dense arrays vertically aligned carbon nanofiber forests. We found that much of the vertically aligned carbon nanofiber sidewalls were functionalized and biologically accessible by this method---the absolute number of DNA molecules hybridized to DNA-functionalized nanofiber electrodes was ˜8 times higher than the number of DNA molecules hybridized to flat glassy carbon electrodes and implies that nanofiber forest sensors may facilitate higher sensitivity to target DNA sequences per unit area. We also used the photochemical method

  9. 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.

  10. High performance carbon nanotube - polymer nanofiber hybrid fabrics

    Science.gov (United States)

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

    2015-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Saeed Ghaffarpour Jahromi

    2015-09-01

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

  12. Effect of twist and porosity on the electrical conductivity of carbon nanofiber yarns

    Science.gov (United States)

    Chawla, S.; Naraghi, M.; Davoudi, A.

    2013-06-01

    This study focuses on the effect of twist and porosity on the electrical conductivity of carbon nanofiber (CNF) yarns. The process of fabrication of CNF yarns included the synthesis of aligned ribbons of polyacrylonitrile (PAN) nanofibers via electrospinning. The PAN ribbons were twisted into yarns with twist levels ranging from zero twist to high twists of 1300 turn per meter (tpm). The twist imposed on the ribbons substantially improved the interactions between nanofibers and reduced the porosity. The PAN yarns were subsequently stabilized in air, and then carbonized in nitrogen at 1100 ° C for 1 h. Compressive stresses developed between the PAN nanofibers as a result of twist promoted interfusion between neighboring nanofibers, which was accelerated by heating the yarns during stabilization to temperatures above the glass transition of PAN. The electrical conductivity of the yarns was measured with a four point probe measurement technique. Although increasing the twist promotes electrical conductivity between nanofibers by forming junctions between them, our results indicate that the electrical conductivity does not continuously increase with increasing twist, but reaches a threshold value after which it starts to decrease. The causes for this behavior were studied through experimental techniques and further explored using a yarn-equivalent electrical circuit model.

  13. Microstructure transformation of carbon nanofibers during graphitization

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  14. Potential applications of nanofiber textile covered by carbon coatings

    Directory of Open Access Journals (Sweden)

    Z. Rożek

    2008-03-01

    Full Text Available Purpose: Nanospider technology is modified electrospinning method for production nanofiber textile from polymer solutions. This material can be used as wound dressing and filter materials for example. Carbon coatings deposited onto surface of polymer nanofiber textiles are predicted to improve filtration effectivity of filters and bioactivity of wound dressings. Carbon coatings have been produced by Microwave Radio Frequency Plasma Assisted Chemical Vapor Deposition (MW/RF PACVD method.Design/methodology/approach: Carbon coatings were deposited on polymer nanofiber textile by MW/RF PACVD method. Nanocomposite obtained in this way was characterized by the contact angle studies and by scanning electron microscope (SEM.Findings: Carbon coatings can be deposited on the polymer nanofibers by MW/RF PACVD method. Content of diamond phase in produced carbon coatings has been confirmed by wetability test. A SEM microscopic images have shown that the spaces between the nanofibers have not been closed by the material of the film.Research limitations/implications: MW/RF PACVD makes carbon coating synthesis possible in lower temperature, what is essential in case of applying the polymer substrate. Use of any other method than MW/RF PACVD for deposition of carbon coatings onto polymer nanofiber textile is not covered in this paper.Practical implications: Nanofiber textile produced by Nanospider is very good mechanical filter. Carbon onto surface of nanofibers can cause from this material active filter. Since this nanocomposite enables the transport of oxygen and exudate, simultaneously is impenetrable for bacteria or even viruses, it can be used for wound dressing.Originality/value: It is our belief that we are first to have deposited carbon coatings on nanofiber textile. We hope that in this way we have prepared very good material for filtration of air and for wound dressing.

  15. Evaluation of carbon fiber composites modified by in situ incorporation of carbon nanofibers

    Directory of Open Access Journals (Sweden)

    André Navarro de Miranda

    2011-12-01

    Full Text Available Nano-carbon materials, such as carbon nanotubes and carbon nanofibers, are being thought to be used as multifunctional reinforcement in composites. The growing of carbon nanofiber at the carbon fiber/epoxy interface results in composites having better electrical properties than conventional carbon fiber/epoxy composites. In this work, carbon nanofibers were grown in situ over the surface of a carbon fiber fabric by chemical vapor deposition. Specimens of carbon fiber/nanofiber/epoxy (CF/CNF/epoxy composites were molded and electrical conductivity was measured. Also, the CF/CNF/epoxy composites were tested under flexure and interlaminar shear. The results showed an overall reduction in mechanical properties as a function of added nanofiber, although electrical conductivity increased up to 74% with the addition of nanofibers. Thus CF/CNF/epoxy composites can be used as electrical dissipation discharge materials.

  16. Improving conducting polymer electrochromic speeds and depositing aligned polymeric nanofibers by electrospinning process

    Science.gov (United States)

    Asemota, Chris I.

    . Lastly, the alignment of electrospun nanofibers during electrospinning was investigated to prepare composites of aligned nanofiber mats on macro-mesh fabric, and control alignment by non-conventional methods. Nanofibers produced during electrospinning are usually collected as non-woven randomly oriented fibers, but by manipulating the electric field at the collector, aligned nanofibers were obtained. Further modifications using a mesh fabric as collector, or using non-conventional conductive surfaces, deposition of continuous and aligned nanofibers of poly lactic acid was achieved.

  17. Ultrasensitive, Label Free, Chemiresistive Nanobiosensor Using Multiwalled Carbon Nanotubes Embedded Electrospun SU-8 Nanofibers

    Directory of Open Access Journals (Sweden)

    Matta Durga Prakash

    2016-08-01

    Full Text Available This paper reports the synthesis and fabrication of aligned electrospun nanofibers derived out of multiwalled carbon nanotubes (MWCNTs embedded SU-8 photoresist, which are targeted towards ultrasensitive biosensor applications. The ultrasensitivity (detection in the range of fg/mL and the specificity of these biosensors were achieved by complementing the inherent advantages of MWCNTs such as high surface to volume ratio and excellent electrical and transduction properties with the ease of surface functionalization of SU-8. The electrospinning process was optimized to precisely align nanofibers in between two electrodes of a copper microelectrode array. MWCNTs not only enhance the conductivity of SU-8 nanofibers but also act as transduction elements. In this paper, MWCNTs were embedded way beyond the percolation threshold and the optimum percentage loading of MWCNTs for maximizing the conductivity of nanofibers was figured out experimentally. As a proof of concept, the detection of myoglobin, an important biomarker for on-set of Acute Myocardial Infection (AMI has been demonstrated by functionalizing the nanofibers with anti-myoglobin antibodies and carrying out detection using a chemiresistive method. This simple and robust device yielded a detection limit of 6 fg/mL.

  18. Ultrasensitive, Label Free, Chemiresistive Nanobiosensor Using Multiwalled Carbon Nanotubes Embedded Electrospun SU-8 Nanofibers.

    Science.gov (United States)

    Durga Prakash, Matta; Vanjari, Siva Rama Krishna; Sharma, Chandra Shekhar; Singh, Shiv Govind

    2016-01-01

    This paper reports the synthesis and fabrication of aligned electrospun nanofibers derived out of multiwalled carbon nanotubes (MWCNTs) embedded SU-8 photoresist, which are targeted towards ultrasensitive biosensor applications. The ultrasensitivity (detection in the range of fg/mL) and the specificity of these biosensors were achieved by complementing the inherent advantages of MWCNTs such as high surface to volume ratio and excellent electrical and transduction properties with the ease of surface functionalization of SU-8. The electrospinning process was optimized to precisely align nanofibers in between two electrodes of a copper microelectrode array. MWCNTs not only enhance the conductivity of SU-8 nanofibers but also act as transduction elements. In this paper, MWCNTs were embedded way beyond the percolation threshold and the optimum percentage loading of MWCNTs for maximizing the conductivity of nanofibers was figured out experimentally. As a proof of concept, the detection of myoglobin, an important biomarker for on-set of Acute Myocardial Infection (AMI) has been demonstrated by functionalizing the nanofibers with anti-myoglobin antibodies and carrying out detection using a chemiresistive method. This simple and robust device yielded a detection limit of 6 fg/mL. PMID:27563905

  19. Nanofiber Alignment Regulates NIH3T3 Cell Orientation and Cytoskeletal Gene Expression on Electrospun PCL+Gelatin Nanofibers.

    Science.gov (United States)

    Fee, Timothy; Surianarayanan, Swetha; Downs, Crawford; Zhou, Yong; Berry, Joel

    2016-01-01

    To examine the influence of substrate topology on the behavior of fibroblasts, tissue engineering scaffolds were electrospun from polycaprolactone (PCL) and a blend of PCL and gelatin (PCL+Gel) to produce matrices with both random and aligned nanofibrous orientations. The addition of gelatin to the scaffold was shown to increase the hydrophilicity of the PCL matrix and to increase the proliferation of NIH3T3 cells compared to scaffolds of PCL alone. The orientation of nanofibers within the matrix did not have an effect on the proliferation of adherent cells, but cells on aligned substrates were shown to elongate and align parallel to the direction of substrate fiber alignment. A microarray of cyotoskeleton regulators was probed to examine differences in gene expression between cells grown on an aligned and randomly oriented substrates. It was found that transcriptional expression of eight genes was statistically different between the two conditions, with all of them being upregulated in the aligned condition. The proteins encoded by these genes are linked to production and polymerization of actin microfilaments, as well as focal adhesion assembly. Taken together, the data indicates NIH3T3 fibroblasts on aligned substrates align themselves parallel with their substrate and increase production of actin and focal adhesion related genes. PMID:27196306

  20. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

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

  1. Silicon Whisker and Carbon Nanofiber Composite Anode Project

    Data.gov (United States)

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

  2. Surface plasmon polariton generation by light scattering off aligned organic nanofibers

    DEFF Research Database (Denmark)

    Skovsen, Esben; Søndergaard, Thomas; Fiutowski, Jacek;

    2012-01-01

    Leakage radiation spectroscopy has been applied to study surface plasmon polariton (SPP) generation by light scattered off aligned organic nanofibers deposited on a thin silver film. The efficiency of SPP generation was studied by angularly resolved leakage radiation spectroscopy as a function...

  3. Continuous High-Aligned Polyacrylonitrile Electrospun Nanofibers Yarns via Circular Deposition on Water Bath.

    Science.gov (United States)

    Bin, Yu; Hao, Yu; Zhu, Meifang; Wang, Hongzhi

    2016-06-01

    A novel strategy for preparing high-aligned continuous Polyacrylonitrile (PAN) electrospun nanofibers yarns is introduced. The yarn is rolled up from circular deposition, which can be changed by controlling the humidity of spinning environment. High-aligned yarn is obtained with the rolling speed of 57 m/min. Very few defects are found in the received yarn. Also the as-spun yarn is drawn in hot water bath to improve its mechanical properties further. The mechanical properties and X-Ray Diffraction (XRD) tests are systematically investigated. The tensile strength of the as-spun yarn rolled with 57 m/min can reach 240 MPa, close to that of as-spun fibers from wet spinning. Furthermore, after drawn of 5 ratios, tensile strength of yarn comes to 580 MPa, which broaden the applied fields of electrospun nanofibers. In addition, the forming mechanism of yarn in the water bath is analyzed and compared with the previous work. Actually, it can be testified experimentally that PAN nanofibers yarn has the same mechanical properties as that prepared with the other approaches with the same testing conditions in this work. The continuous high-aligned electrospun nanofibers PAN yarn via circular deposition in this paper is capable of meeting the requirement of the more applications needing of high mechanical properties and alignment degree. PMID:27427608

  4. 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.

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

    Science.gov (United States)

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

    2014-07-01

    Lightweight carbon materials of effective electromagnetic interference (EMI) shielding have attracted increasing interest because of rapid development of smart communication devices. To meet the requirement in portable electronic devices, flexible shielding materials with ultrathin characteristic have been pursued for this purpose. In this work, we demonstrated a facile strategy for scalable fabrication of flexible all-carbon networks, where the insulting polymeric frames and interfaces have been well eliminated. Microscopically, a novel carbon nanofiber-graphene nanosheet-carbon nanofiber (CNF-GN-CNF) heterojunction, which plays the dominant role as the interfacial modifier, has been observed in the as-fabricated networks. With the presence of CNF-GN-CNF heterojunctions, the all-carbon networks exhibit much increased electrical properties, resulting in the great enhancement of EMI shielding performance. The related mechanism for engineering the CNF interfaces based on the CNF-GN-CNF heterojunctions has been discussed. Implication of the results suggests that the lightweight all-carbon networks, whose thickness and density are much smaller than other graphene/polymer composites, present more promising potential as thin shielding materials in flexible portable electronics. PMID:24914611

  6. Control of spatial cell attachment on carbon nanofiber patterns on polycarbonate urethane

    OpenAIRE

    Bajaj, Piyush; Khang, Dongwoo; Webster, Thomas J

    2006-01-01

    A highly aligned pattern of carbon nanofibers (CNF) on polycarbonate urethane (PCU) for tissue engineering applications was created by placing a CNF–ethanol solution in 30μm width copper grid grooves on top of PCU. In vitro results provided the first evidence that fibroblasts and vascular smooth muscle cells selectively adhered to the PCU regions. However, endothelial cells did not display a preference for adhesion to the CNF compared with PCU regions. Previous studies have shown selective ad...

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

    Directory of Open Access Journals (Sweden)

    Zhongfu Zhao and Jan Gou

    2009-01-01

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

  8. Cellular compatibility of RGD-modified chitosan nanofibers with aligned or random orientation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanyan; Lue Lanxin; Feng Zhangqi; Xiao Zhongdang; Huang Ningping, E-mail: nphuang@seu.edu.c, E-mail: zdxiao@seu.edu.c [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)

    2010-10-01

    Aligned and randomly oriented chitosan nanofibers were prepared by electrospinning. The fibers were modified with the RGD cell-adhesive peptide through a heterobifunctional crosslinker containing a segment of poly(ethylene glycol) (PEG). PEG rendered the surface hydrophilic and provided flexible spacers, allowing the preservation of the bioactivity of further captured RGD peptides. NIH 3T3 cells were used to test the cellular compatibility of these chitosan nanofibrous scaffolds. Cell morphology and viability were investigated by SEM, fluorescent staining and cell counting. The results indicate that RGD-modified surfaces significantly improve the cellular compatibility of chitosan nanofibers and suggest a good candidate as a scaffold employed in tissue engineering.

  9. UNIAXIAL ALIGNMENT OF POLY(3-HEXYLTHIOPHENE) NANOFIBERS BY ZONE-CASTING APPROACH

    Institute of Scientific and Technical Information of China (English)

    Xiang Gao; Ru-bo Xing; Jian-gang Liu; Yan-chun Han

    2013-01-01

    The preparation of large area coverage of films with uniaxially aligned poly(3-hexylthiophene) (P3HT) nanofibers by using zone-casting approach is reported.The length and the orientation of the nanofibers are defined by the solubility of the solvent,the P3HT molecular weight and the substrate temperature.The length of the oriented nanofibers could be increased from 1 μm to more than 10 μm by adding poor solvent into the P3HT solution.It is found that for P3HT of relatively low molecular weight,a solvent with relatively low solubility has to be chosen to get the oriented film.While for the high molecular weight P3HT,the solvent with a relatively high solubility has to be used.The well-aligned film could be obtained because of the solute concentration gradient in the region where the critical concentration is reached during the zone-casting process.Particularly,the solvent evaporation rate and crystallization rate must be chosen properly to satisfy the stationary conditions above,which were controlled by an appropriate choice of solvent and substrate temperature.The film prepared by zone-casting approach had microcrystalline P3HT domains with more inter-chain order than spin-coating film.Meanwhile,the P3HT π-π stacking direction was parallel to the alignment direction of the nanofibers.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

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

    Science.gov (United States)

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

    2014-03-01

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

  13. PREPARATION OF CARBON NANOFIBERS BY POLYMER BLEND TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  14. CHARACTERIZATION AND ADSORPTION PROPERTIES OF POROUS CARBON NANOFIBER GRANULES

    Institute of Scientific and Technical Information of China (English)

    Jiuling Chen; Qinghai Chen; Yongdan Li

    2006-01-01

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

  15. Aligned Nanofibers from Polypyrrole/Graphene as Electrodes for Regeneration of Optic Nerve via Electrical Stimulation.

    Science.gov (United States)

    Yan, Lu; Zhao, Bingxin; Liu, Xiaohong; Li, Xuan; Zeng, Chao; Shi, Haiyan; Xu, Xiaoxue; Lin, Tong; Dai, Liming; Liu, Yong

    2016-03-23

    The damage of optic nerve will cause permanent visual field loss and irreversible ocular diseases, such as glaucoma. The damage of optic nerve is mainly derived from the atrophy, apoptosis or death of retinal ganglion cells (RGCs). Though some progress has been achieved on electronic retinal implants that can electrically stimulate undamaged parts of RGCs or retina to transfer signals, stimulated self-repair/regeneration of RGCs has not been realized yet. The key challenge for development of electrically stimulated regeneration of RGCs is the selection of stimulation electrodes with a sufficient safe charge injection limit (Q(inj), i.e., electrochemical capacitance). Most traditional electrodes tend to have low Q(inj) values. Herein, we synthesized polypyrrole functionalized graphene (PPy-G) via a facile but efficient polymerization-enhanced ball milling method for the first time. This technique could not only efficiently introduce electron-acceptor nitrogen to enhance capacitance, but also remain a conductive platform-the π-π conjugated carbon plane for charge transportation. PPy-G based aligned nanofibers were subsequently fabricated for guided growth and electrical stimulation (ES) of RGCs. Significantly enhanced viability, neurite outgrowth and antiaging ability of RGCs were observed after ES, suggesting possibilities for regeneration of optic nerve via ES on the suitable nanoelectrodes. PMID:26926578

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    NARCIS (Netherlands)

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

    2005-01-01

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

  19. 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

  20. Carbon Nanofibers as Catalyst Support for Noble Metals

    NARCIS (Netherlands)

    Toebes, M.L.

    2004-01-01

    In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work

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

    Science.gov (United States)

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

    2008-01-01

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

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

    NARCIS (Netherlands)

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

    2012-01-01

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

  3. Electromagnetic interference shielding characteristics of carbon nanofiber-polymer composites.

    Science.gov (United States)

    Yang, Yonglai; Guptal, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2007-02-01

    Electromagnetic interference (EMI) shielding characteristics of carbon nanofiber-polystyrene composites were investigated in the frequency range of 12.4-18 GHz (Ku-band). It was observed that the shielding effectiveness of such composites was frequency independent, and increased with increasing carbon nanofiber loading within Ku-band. The experimental data exhibited that the shielding effectiveness of the polymer composite containing 20 wt% carbon nanofibers could reach more than 36 dB in the measured frequency region, indicating such composites can be applied to the potential EMI shielding materials. In addition, the results showed that the contribution of reflection to the EMI shielding effectiveness was much larger than that of absorption, implying the primary EMI shielding mechanism of such composites was reflection of electromagnetic radiation within Ku-band. PMID:17450793

  4. Conductive Behaviors of Carbon Nanofibers Reinforced Epoxy Composites

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  5. 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. PMID:26428148

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

    Science.gov (United States)

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

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

  7. 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.

  8. Significantly improving electromagnetic performance of nanopaper and its shape-memory nanocomposite by aligned carbon nanotubes

    Science.gov (United States)

    Lu, Haibao; Gou, Jan

    2012-04-01

    A new nanopaper that exhibits exciting electrical and electromagnetic performances is fabricated by incorporating magnetically aligned carbon nanotube (CNT) with carbon nanofibers (CNFs). Electromagnetic CNTs were blended with and aligned into the nanopaper using a magnetic field, to significantly improve the electrical and electromagnetic performances of nanopaper and its enabled shape-memory polymer (SMP) composite. The morphology and structure of the aligned CNT arrays in nanopaper were characterized with scanning electronic microscopy (SEM). A continuous and compact network of CNFs and aligned CNTs indicated that the nanopaper could have highly conductive properties. Furthermore, the electromagnetic interference (EMI) shielding efficiency of the SMP composites with different weight content of aligned CNT arrays was characterized. Finally, the aligned CNT arrays in nanopapers were employed to achieve the electrical actuation and accelerate the recovery speed of SMP composites.

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

    Directory of Open Access Journals (Sweden)

    S. del Rio

    2012-03-01

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

  10. Charge Injection From Carbon Nanofibers Into Hexane Under Ambient Conditions

    NARCIS (Netherlands)

    Agiral, A.; Eral, H.B.; Ende, van den D.; Gardeniers, J.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

  11. Electrochemical characteristics of activated carbon nanofiber electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-25

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

  12. Carbon Nanofibers as Catalyst Support for Noble Metals

    OpenAIRE

    Toebes, M.L.

    2004-01-01

    In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work described in this thesis has been the exploration of the potential of CNF as catalyst support material, notably for platinum and ruthenium, and its role in the performance of these catalysts in hyd...

  13. A catechol biosensor based on electrospun carbon nanofibers

    OpenAIRE

    Dawei Li; Zengyuan Pang; Xiaodong Chen; Lei Luo; Yibing Cai; Qufu Wei

    2014-01-01

    Carbon nanofibers (CNFs) were prepared by combining electrospinning with a high-temperature carbonization technique. And a polyphenol biosensor was fabricated by blending the obtained CNFs with laccase and Nafion. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FE-SEM) were, respectively, employed to investigate the structures and morphologies of the CNFs and of the mixtures. Cyclic voltammetry and chronoamperometry were empl...

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

    OpenAIRE

    Manea, F.; Motoc, S.; Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); 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 nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

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

    Science.gov (United States)

    Manea, Florica; Motoc, Sorina; Pop, Aniela; Remes, Adriana; Schoonman, Joop

    2012-06-01

    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 nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2016-06-01

    Carbon Nanofibers (CNFs) have shown great potential to improve the physical and mechanical properties of conventional Fiber Reinforced Polymer Composites (FRPCs) surface. Excellent dispersion CNFs into water or polymer matrix was very crucial to get good quality CNFs enhanced FRPCs. Because of the hydrophobic properties of CNFs, we apply the reversible switching principles to transfer the hydrophobic surface into hydrophilic surface by growing polyaniline nanograss on the surface of CNFs which was carried out in hydrochloric acid condition. Incorporating CNFs into FRPCs as a surface layer named CNFs Nanopaper to increase the erosion resistance and electrical conductivity in this research which was very important in the wind energy field. In order to get high quality dispersed CNFs suspension, a sonication unit was used to detangle and uniform disperse the functionalized CNFs. A filter with vacuum pressure used to filter the suspension of CNFs onto Carbon veil to make CNFs Nanopaper. Vacuum Aided Resin Transfer Modeling (VARTM) process was used to fabricate Nano-enhanced FRPCs samples. In order to characterize the mechanical properties, three point bending experiment was measured. The flexural strength capacity and deformation resistance and behavior were compared and analyzed. In this paper, we discussed the methods used and provided experimental parameter and experimental results. PMID:27427606

  19. 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.

  20. Layered chitosan-collagen hydrogel/aligned PLLA nanofiber construct for flexor tendon regeneration.

    Science.gov (United States)

    Deepthi, S; Nivedhitha Sundaram, M; Deepti Kadavan, J; Jayakumar, R

    2016-11-20

    The aim of our study was to develop a tendon construct of electrospun aligned poly (l-lactic acid) (PLLA) nanofibers, to mimic the aligned collagen fiber bundles and layering PLLA fibers with chitosan-collagen hydrogel, to mimic the glycosaminoglycans of sheath ECM for tendon regeneration. The hydrogel coated electrospun membrane was rolled and an outer coating of alginate gel was given to prevent peritendinous adhesion. The developed constructs were characterized by SEM, FT-IR and tensile testing. Protein adsorption studies showed lower protein adsorption on coated scaffolds compared to uncoated scaffolds. The samples were proven to be non-toxic to tenocytes. The chitosan-collagen/PLLA uncoated scaffolds and alginate gel coated chitosan-collagen/PLLA scaffolds showed good cell proliferation. The tenocytes showed good attachment and spreading on the scaffolds. This study indicated that the developed chitosan-collagen/PLLA/alginate scaffold would be suitable for flexor tendon regeneration. PMID:27561521

  1. Synthesis and characterization of multiwalled CNT-PAN based composite carbon nanofibers via electrospinning.

    Science.gov (United States)

    Kaur, Narinder; Kumar, Vipin; Dhakate, Sanjay R

    2016-01-01

    Electrospun fibrous membranes find place in diverse applications like sensors, filters, fuel cell membranes, scaffolds for tissue engineering, organic electronics etc. The objectives of present work are to electrospun polyacrylonitrile (PAN) nanofibers and PAN-CNT nanocomposite nanofibers and convert into carbon nanofiber and carbon-CNT composite nanofiber. The work was divided into two parts, development of nanofibers and composite nanofiber. The PAN nanofibers were produced from 9 wt% PAN solution by electrospinning technique. In another case PAN-CNT composite nanofibers were developed from different concentrations of MWCNTs (1-3 wt%) in 9 wt% PAN solution by electrospinning. Both types of nanofibers were undergone through oxidation, stabilization, carbonization and graphitization. At each stage of processing of carbon and carbon-CNT composite nanofibers were characterized by SEM, AFM, TGA and XRD. It was observed that diameter of nanofiber varies with processing parameters such as applied voltage tip to collector distance, flow rate of solution and polymer concentrations etc. while in case of PAN-CNT composite nanofiber diameter decreases with increasing concentration of CNT in PAN solution. Also with stabilization, carbonization and graphitization diameter of nanofiber decreases. SEM images shows that the minimum fiber diameter in case of 3 wt% of CNT solution because as viscosity increases it reduces the phase separation of PAN and solvent and as a consequence increases in the fiber diameter. AFM images shows that surface of film is irregular which give idea about mat type orientation of fibers. XRD results show that degree of graphitization increases on increasing CNT concentration because of additional stresses exerting on the nanofiber surface in the immediate vicinity of CNTs. TGA results shows wt loss decreases as CNT concentration increases in fibers. PMID:27217998

  2. Synthesis and Characterization of Carbon nanofibers on Co and Cu Catalysts by Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eunsil; Kim, Jongwon; Lee, Changseop [Keimyung Univ., Daegu (Korea, Republic of)

    2014-06-15

    This study reports on the synthesis of carbon nanofibers via chemical vapor deposition using Co and Cu as catalysts. In order to investigate the suitability of their catalytic activity for the growth of nanofibers, we prepared catalysts for the synthesis of carbon nanofibers with Cobalt nitrate and Copper nitrate, and found the optimum concentration of each respective catalyst. Then we made them react with Aluminum nitrate and Ammonium Molybdate to form precipitates. The precipitates were dried at a temperature of 110 .deg. C in order to be prepared into catalyst powder. The catalyst was sparsely and thinly spread on a quartz tube boat to grow carbon nanofibers via thermal chemical vapor deposition. The characteristics of the synthesized carbon nanofibers were analyzed through SEM, EDS, XRD, Raman, XPS, and TG/DTA, and the specific surface area was measured via BET. Consequently, the characteristics of the synthesized carbon nanofibers were greatly influenced by the concentration ratio of metal catalysts. In particular, uniform carbon nanofibers of 27 nm in diameter grew when the concentration ratio of Co and Cu was 6:4 at 700 .deg. C of calcination temperature; carbon nanofibers synthesized under such conditions showed the best crystallizability, compared to carbon nanofibers synthesized with metal catalysts under different concentration ratios, and revealed 1.26 high amorphicity as well as 292 m{sup 2}g{sup -1} high specific surface area.

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

    OpenAIRE

    Mamun, A. A.; Y.M. Ahmed; S.A. Muyibi; M.F.R. Al-Khatib; A.T. Jameel; M.A. AlSaadi

    2016-01-01

    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 s...

  4. 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. PMID:27632072

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

    OpenAIRE

    Ding Nan; Zheng-Hong Huang; Ruitao Lv; Yuxiao Lin; Lu Yang; Xiaoliang Yu; Ling Ye; Wanci Shen; Hongyu Sun; Feiyu Kang

    2014-01-01

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

  7. The influence of type-I collagen-coated PLLA aligned nanofibers on growth of blood outgrowth endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Feng Zhangqi; Huang Ningping; Wang Yichun; Gu Zhongze [State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096 (China); Lu Huijun [Department of Vascular Surgery, Wuxi People' s Hospital, Wuxi 214023 (China); Leach, Michelle K [Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Liu Changjian, E-mail: gu@seu.edu.c [Department of Vascular Surgery, The Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing 210008 (China)

    2010-12-15

    Nanofibrous scaffolds have been applied widely in tissue engineering to simulate the nanostructure of natural extracellular matrix (ECM) and promote cell bioactivity. The aim of this study was to design a biocompatible nanofibrous scaffold for blood outgrowth endothelial cells (BOECs) and investigate the interaction between the topography of the nanofibrous scaffold and cell growth. Poly(l-lactic acid) (PLLA) random and aligned nanofibers with a uniform diameter distribution were fabricated by electrospinning. NH{sub 3} plasma etching was used to create a hydrophilic surface on the nanofibers to improve type-I collagen adsorption; the conditions of the NH{sub 3} plasma etching were optimized by XPS and water contact angle analysis. Cell attachment, proliferation, viability, phenotype and morphology of BOECs cultured on type-I collagen-coated PLLA film (col-Film), random fibers (col-RFs) and aligned fibers (col-AFs) were detected over a 7 day culture period. The results showed that collagen-coated PLLA nanofibers improved cell attachment and proliferation; col-AFs induced the directional growth of cells along the aligned nanofibers and enhanced endothelialization. We suggest that col-AFs may be a potential implantable scaffold for vascular tissue engineering.

  8. Effects of aggregation of poly(3-hexylthiophene) in solution on uniaxial alignment of nanofibers during zone casting

    Institute of Scientific and Technical Information of China (English)

    Xiang Gao; Jian-Gang Liu; Yue Sun; Ru-Bo Xing; Yan-Chun Han

    2013-01-01

    We report on the effects of aggregation of P3HT with ordered conformation in solution on improving the uniaxial alignment of the P3HT nanofibers by zone casting.Two approaches were employed to change the aggregation of P3HT:P3HT blending with coil insulating polymer and ultrasonic oscillating.The insulator polymer (i.e.PS) which has good solubility in the solution would disturb the aggregation of P3HT to prevent the chains entanglement.The ultrasonic oscillation can further improve the P3HT aggregation with ordered conformation in the solution.As a result,the P3HT nanofibers in the film grew much orientedly by zone casting the ultrasonic oscillating P3HT/PS polymer blends solution than the same solvent P3HT solution without ultrasonic oscillating and blending.The P3HT π-π stacking direction is parallel to the alignment direction of the nanofibers.Meanwhile,the P3HT/PS blend ratio and PS molecular weight have influence on the uniaxial alignment of P3HT nanofibers.Only P3HT/PS is 1∶1,the P3HT nanoflbers oriented well.The low molecular weight PS can make the P3HT nanoflbers orient better than that of the high molecular weight.

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

    Science.gov (United States)

    Yan, Jing; Jeong, Young Gyu

    2016-06-22

    Piezoelectric nanogenerators, harvesting energy from mechanical stimuli in our living environments, hold great promise to power sustainable self-sufficient micro/nanosystems and mobile/portable electronics. BaTiO3 as a lead-free material with high piezoelectric coefficient and dielectric constant has been widely examined to realize nanogenerators, capacitors, sensors, etc. In this study, polydimethylsiloxane (PDMS)-based flexible composites including BaTiO3 nanofibers with different alignment modes were manufactured and their piezoelectric performance was examined. For the study, BaTiO3 nanofibers were prepared by an electrospinning technique utilizing a sol-gel precursor and following calcination process, and they were then aligned vertically or horizontally or randomly in PDMS matrix-based nanogenerators. The morphological structures of BaTiO3 nanofibers and their nanogenerators were analyzed by using SEM images. The crystal structures of the nanogenerators before and after poling were characterized by X-ray diffraction. The dielectric and piezoelectric properties of the nanogenerators were investigated as a function of the nanofiber alignment mode. The nanogenerator with BaTiO3 nanofibers aligned vertically in the PDMS matrix sheet achieved high piezoelectric performance of an output power of 0.1841 μW with maximum voltage of 2.67 V and current of 261.40 nA under a low mechanical stress of 0.002 MPa, in addition to a high dielectric constant of 40.23 at 100 Hz. The harvested energy could thus power a commercial LED directly or be stored into capacitors after rectification. PMID:27237223

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

    Science.gov (United States)

    Yan, Jing; Jeong, Young Gyu

    2016-06-22

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

  11. Electricity Generation from Microbial Fuel Cell with Polypyrrole-Coated Carbon Nanofiber Composite.

    Science.gov (United States)

    Roh, Sung-Hee

    2015-02-01

    Polyacrylonitrile (PAN) nanofibers, with and without embedded carbon nanotubes (CNTs) were fabricated by the electrospinning process. Polypyrrole (PPy) was coated on the activated PAN/CNT nanofiber by in-situ chemical polymerization in order to improve the electrochemical performance. The electrocatalytic behaviors of the PPy-PAN/CNT composite anode were investigated by means of cyclic voltammetry to evaluate as the anode for microbial fuel cells (MFCs) application. In comparison with unmodified carbon cloth (CC) anodes, PPy-PAN/CNT nanofiber composite showed the improvement of the maximum power density by 40%. The PPy-PAN/CNT nanofiber composite electrode therefore offers good prospects for application in MFCs. PMID:26353717

  12. 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

  13. 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.

  14. 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 even...

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2013-10-01

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

  17. Fabrication of Aligned Nanofiber Polymer Yarn Networks for Anisotropic Soft Tissue Scaffolds.

    Science.gov (United States)

    Wu, Shaohua; Duan, Bin; Liu, Penghong; Zhang, Caidan; Qin, Xiaohong; Butcher, Jonathan T

    2016-07-01

    Nanofibrous scaffolds with defined architectures and anisotropic mechanical properties are attractive for many tissue engineering and regenerative medicine applications. Here, a novel electrospinning system is developed and implemented to fabricate continuous processable uniaxially aligned nanofiber yarns (UANY). UANY were processed into fibrous tissue scaffolds with defined anisotropic material properties using various textile-forming technologies, i.e., braiding, weaving, and knitting techniques. UANY braiding dramatically increased overall stiffness and strength compared to the same number of UANY unbraided. Human adipose derived stem cells (HADSC) cultured on UANY or woven and knitted 3D scaffolds aligned along local fiber direction and were >90% viable throughout 21 days. Importantly, UANY supported biochemical induction of HADSC differentiation toward smooth muscle and osteogenic lineages. Moreover, we integrated an anisotropic woven fiber mesh within a bioactive hydrogel to mimic the complex microstructure and mechanical behavior of valve tissues. Human aortic valve interstitial cells (HAVIC) and human aortic root smooth muscle cells (HASMC) were separately encapsulated within hydrogel/woven fabric composite scaffolds for generating scaffolds with anisotropic biomechanics and valve ECM like microenvironment for heart valve tissue engineering. UANY have great potential as building blocks for generating fiber-shaped tissues or tissue microstructures with complex architectures. PMID:27304080

  18. Electrospinning of single wall carbon nanotube reinforced aligned fibrils and yarns

    Science.gov (United States)

    Lam, Hoa Le

    Commercial carbon fibers produced from a polyacrylonitrile (PAN) precursor have reached their performance limit. The approach in this study involves the use of single carbon nanotubes (SWNT) with an ultra-high elastic modulus of approximately ˜1 TPa and tensile strength of ˜37 GPa at a breaking strain of ˜6% to reinforce PAN. In order to translate these extraordinary properties to a higher order structure, the need for a media to carry and assemble the SWNT into continuous fibers or yarns is necessary. Effective translation of properties can only be achieved through uniform distribution of SWNT and their alignment in the fiber axis. This has been one of the major challenges since SWNTs tend to agglomerate due to high van der Waals attraction between tubes. It is the goal of this study to develop dispersion technique(s) for the SWNT and process them into aligned fibers utilizing the electrospinning process. The electrospun nanofibers were then characterized by various techniques such as ESEM, Raman microspectroscopy, HRTEM, and tensile testing. Composite nanofibers containing various contents of SWNT up to 10 wt. % with diameter ranging from 40--300 nm were successfully electrospun through varying the polymer concentration and spinning parameters. The inclusion of SWNTs and their alignment in the fiber axis were confirmed by Raman microspectroscopy, polarized Raman and HRETEM. The failure mechanism of the nanofibers was investigated by HRTEM through fiber surface fracture. A two stage rupture mechanism was observed where crazing initiates at a surface defect followed by SWNTs pulling out of the PAN matrix. Such mechanisms consume energy therefore strengthening and toughening the fibers. Mechanical drawing of the fiber prior to heat treatment induced molecular orientation resulting in oriented graphite layers in the carbonized fibers. This study has established a processing base and characterization techniques to support the design and development of SWNT

  19. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    Science.gov (United States)

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed. PMID:16060155

  20. The Formation of Carbon Nanofibers on Powdered Activated Carbon Impregnated with Nickel

    Science.gov (United States)

    Ahmed, Y. M.; Al-Mamun, A. A.; Muyibi, S. A.; Al-Khatib, M. F. R.; Jameel, A. T.; AlSaadi, M. A.

    2009-06-01

    In the present work, the production and characterization of carbon nanofibers (CNFs) composite is reported. Carbon nanofibers (CNF) were produced on powdered activated carbon PAC—impregnated with nickel—by Chemical Vapor Deposition (CVD) of a hydrocarbon in the presence of hydrogen at ˜780° C. The flow rates of carbon source and hydrogen were fixed. The CNFs were formed directly over the impregnated AC. Variable weight percentage ratios of the catalyst salt (Ni+2) were used for the impregnation (1, 3, 5, 7 and 9%, respectively). The product displays a relatively high surface area, essentially constituted by the external surface, and the absence of the bottled pores encountered with activated carbon. FSEM, TEM and TGA were used for the characterization of the product.

  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. A simple method to synthesize carbon nanofibers with a parallel growth mode and their capacitive properties

    International Nuclear Information System (INIS)

    Carbon nanofibers with a parallel growth mode were synthesized by a chemical vapor deposition (CVD) method using a nickel catalyst precursor and acetylene carbon source gas at 550 °C, the growth mechanism and growth model of which were discussed and established, respectively. In the case of no pretreatment, the Brunauer–Emmett–Teller (BET) surface area and total pore volume of the as-synthesized carbon nanofibers were 214 m2·g−1 and 0.36 cm3·g−1, respectively. The maximum specific capacitance of the carbon nanofibers was 205.8 F·g−1, examined at a 0.20 V·s−1 sweep rate. The structure and morphology of the carbon nanofibers were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and x-ray powder diffraction (XRD). (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-01

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

  4. 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.

  5. 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. PMID:22966719

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

    Directory of Open Access Journals (Sweden)

    S. A. Manafi

    2008-01-01

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

  7. 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.

  8. 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.

  9. Plasma coating of carbon nanofibers for enhanced dispersion and interfacial bonding in polymer composites

    International Nuclear Information System (INIS)

    Ultrathin films of polystyrene were deposited on the surfaces of carbon nanofibers using a plasma polymerization treatment. A small percent by weight of these surface-coated nanofibers were incorporated into polystyrene to form a polymer nanocomposite. The plasma coating greatly enhanced the dispersion of the nanofibers in the polymer matrix. High-resolution transmission-electron-microscopy (HRTEM) images revealed an extremely thin film of the polymer layer (∼3 nm) at the interface between the nanofiber and matrix. Tensile test results showed considerably increased strength in the coated nanofiber composite while an adverse effect was observed in the uncoated composites; the former exhibited shear yielding due to enhanced interfacial bonding while the latter fractured in a brittle fashion

  10. 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.

  11. Effects of palladium coating on field-emission properties of carbon nanofibers in a hydrogen plasma

    International Nuclear Information System (INIS)

    Results from electron field-emission studies using arrays of patterned carbon nanofiber bundles are reported. We find that the desired field-emission characteristics were not compromised when a protective coating consisting of a layer of palladium of 5 and 30 nm thickness was applied. Following exposure to a hydrogen plasma for several hours we find that the coatings impede plasma damage significantly, whereas the field-emission properties of uncoated nanofibers degraded much more rapidly. The results demonstrate that carbon nanofibers with protective conformal metal coatings can be integrated into harsh plasma environments enabling a range of applications such as field-ionization ion sources and advanced (micro)-plasma discharges. - Highlights: • Carbon nanofibers were uniformly coated with palladium. • Energy-filtered transmission electron microscope confirms uniformity of coating. • Tips were exposed to atomic hydrogen environment. • Field emission characteristics were measured and compared to uncoated samples. • Coated samples show better field emission properties and longer lifetime

  12. Effects of palladium coating on field-emission properties of carbon nanofibers in a hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Waldmann, Ole [E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Persaud, Arun, E-mail: APersaud@lbl.gov [E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kapadia, Rehan; Takei, Kuniharu [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720 (United States); Allen, Frances I. [E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); Javey, Ali [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720 (United States); Schenkel, Thomas [E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2013-05-01

    Results from electron field-emission studies using arrays of patterned carbon nanofiber bundles are reported. We find that the desired field-emission characteristics were not compromised when a protective coating consisting of a layer of palladium of 5 and 30 nm thickness was applied. Following exposure to a hydrogen plasma for several hours we find that the coatings impede plasma damage significantly, whereas the field-emission properties of uncoated nanofibers degraded much more rapidly. The results demonstrate that carbon nanofibers with protective conformal metal coatings can be integrated into harsh plasma environments enabling a range of applications such as field-ionization ion sources and advanced (micro)-plasma discharges. - Highlights: • Carbon nanofibers were uniformly coated with palladium. • Energy-filtered transmission electron microscope confirms uniformity of coating. • Tips were exposed to atomic hydrogen environment. • Field emission characteristics were measured and compared to uncoated samples. • Coated samples show better field emission properties and longer lifetime.

  13. Direct Electrochemistry of Glucose Oxidase on Novel Free-Standing Nitrogen-Doped Carbon Nanospheres@Carbon Nanofibers Composite Film

    OpenAIRE

    Xueping Zhang; Dong Liu; Libo Li; Tianyan You

    2015-01-01

    We have proposed a novel free-standing nitrogen-doped carbon nanospheres@carbon nanofibers (NCNSs@CNFs) composite film with high processability for the investigation of the direct electron transfer (DET) of glucose oxidase (GOx) and the DET-based glucose biosensing. The composites were simply prepared by controlled thermal treatment of electrospun polypyrrole nanospheres doped polyacrylonitrile nanofibers (PPyNSs@PAN NFs). Without any pretreatment, the as-prepared material can directly serve ...

  14. 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.

  15. Preparation of Aligned Ultra-long and Diameter-controlled Silicon Oxide Nanotubes by Plasma Enhanced Chemical Vapor Deposition Using Electrospun PVP Nanofiber Template

    Science.gov (United States)

    Zhou, Ming; Zhou, Jinyuan; Li, Ruishan; Xie, Erqing

    2010-02-01

    Well-aligned and suspended polyvinyl pyrrolidone (PVP) nanofibers with 8 mm in length were obtained by electrospinning. Using the aligned suspended PVP nanofibers array as template, aligned ultra-long silicon oxide (SiO x) nanotubes with very high aspect ratios have been prepared by plasma-enhanced chemical vapor deposition (PECVD) process. The inner diameter (20-200 nm) and wall thickness (12-90 nm) of tubes were controlled, respectively, by baking the electrospun nanofibers and by coating time without sacrificing the orientation degree and the length of arrays. The micro-PL spectrum of SiO x nanotubes shows a strong blue-green emission with a peak at about 514 nm accompanied by two shoulders around 415 and 624 nm. The blue-green emission is caused by the defects in the nanotubes.

  16. 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.

  17. Carbon nanofiber electrode array for electrochemical detection of dopamine using fast scan cyclic voltammetry

    OpenAIRE

    Koehne, Jessica E.; Marsh, Michael; Boakye, Adwoa; Douglas, Brandon; Kim, In Yong; Chang, Su-Youne; Jang, Dong-Pyo; Bennet, Kevin E.; Kimble, Christopher; Andrews, Russell; Meyyappan, M.; Lee, Kendall H.

    2011-01-01

    A carbon nanofiber (CNF) electrode array was integrated with the Wireless Instantaneous Neurotransmitter Sensor System (WINCS) for detection of dopamine using fast scan cyclic voltammetry (FSCV). Dopamine detection performance by CNF arrays was comparable to that of traditional carbon fiber microelectrodes (CFMs), demonstrating that CNF arrays can be utilized as an alternative carbon electrodes for neurochemical monitoring.

  18. 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.

  19. 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.

  20. Preparation and characterization of carbon nanofiber-polymide composites

    Science.gov (United States)

    Li, Xiaobing

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

  1. Vertically aligned nanostructure scanning probe microscope tips

    Science.gov (United States)

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

    2006-12-19

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

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

    Science.gov (United States)

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

    2016-07-01

    Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10(-7) m(2) s(-1)) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b(1.5)∝D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features. PMID:27283144

  3. 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.

  4. Characterisation of hydrophobic carbon nanofiber-silica composite film electrodes for redox liquid immobilisation

    International Nuclear Information System (INIS)

    Carbon (50-150 nm diameter) nanofibers were embedded into easy to prepare thin films of a hydrophobic sol-gel material and cast onto tin-doped indium oxide substrate electrodes. They promote electron transport and allow efficient electrochemical reactions at solid|liquid and at liquid|liquid interfaces. In order to prevent aggregation of carbon nanofibers silica nanoparticles of 7 nm diameter were added into the sol-gel mixture as a 'surfactant' and homogeneous high surface area films were obtained. Scanning electron microscopy reveals the presence of carbon nanofibers at the electrode surface. The results of voltammetric experiments performed in redox probe-ferrocenedimethanol solution in aqueous electrolyte solution indicate that in the absence of organic phase, incomplete wetting within the hydrophobic film of carbon nanofibers can cause hemispherical diffusion regime typical for ultramicroelectrode like behaviour. The hydrophobic film electrode was modified with two types of redox liquids: pure tert-butylferrocene or dissolved in 2-nitrophenyloctylether as a water-insoluble solvent and immersed in aqueous electrolyte solution. With a nanomole deposit of pure redox liquid, stable voltammetric responses are obtained. The presence of carbon nanofibers embedded in the mesoporous matrix substantially increases the efficiency of the electrode process and stability under voltammetric conditions. Also well-defined response for diluted redox liquids is obtained. From measurements in a range of different aqueous electrolyte media a gradual transition from anion transfer dominated to cation transfer dominated processes is inferred depending on the hydrophilicity of the transferring anion or cation

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-30

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

  6. Preparation, Characterization, and Modeling of Carbon Nanofiber/Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Lan-Hui Sun

    2011-01-01

    Full Text Available There is a lack of systematic investigations on both mechanical and electrical properties of carbon nanofiber (CNF-reinforced epoxy matrix nanocomposites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nanocomposites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nanocomposites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nanocomposite with a 1.0 wt% CNFs. The alternate-current (AC electrical properties of the CNF/epoxy nanocomposites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt% (0.058 vol% CNFs and by ten orders of magnitude for nanocomposites with CNF volume fractions higher than 1.0 wt% (0.578 vol%. The percolation threshold (i.e., the critical CNF volume fraction is found to be at 0.057 vol%.

  7. 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.

  8. 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 (pdays culture as compare to P (LLA-CL)/Vt. The in vitro vitamin 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. PMID:27085042

  9. Towards Scalable Binderless Electrodes: Carbon Coated Silicon Nanofiber Paper via Mg Reduction of Electrospun SiO2 Nanofibers

    Science.gov (United States)

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

    2015-02-01

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

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

    Science.gov (United States)

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

    2015-02-06

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

  11. 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.

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

    NARCIS (Netherlands)

    Pacheco Benito, S.; Lefferts, L.

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  14. Influence of reaction parameters on the attachment of a carbon nanofiber layer on Ni foils

    NARCIS (Netherlands)

    Pacheco Benito, Sergio; Lefferts, Leon

    2012-01-01

    Dense carbon (C) and entangled carbon nanofiber (CNF) layers were deposited on nickel foils by decomposition of ethylene in presence of different H2 concentrations at 450 °C for different reaction times. Both C and CNF layer thicknesses increase with time, but samples pre-oxidized at 500 °C normally

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-25

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

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

    Science.gov (United States)

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

    2016-08-01

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

  17. Synthesis and mechanical properties of interconnected carbon nanofiber network reinforced polydimethylsiloxane composites.

    Science.gov (United States)

    Zhao, Z Y; Khatri, N D; Nguyen, K; Song, S Q; Sun, L

    2011-02-01

    Carbon nanofiber (CNF) reinforced elastomer composites with light weight, sustainability of large deformation, chemical stability, corrosion and fatigue resistance, and vibration and noise reduction capability can have positive impact on a wide range of applications. However, this type of composite is still a under studied research area due to the difficulties in material handling and processing. To improve processing control and reproducibility for large scale engineering applications, cost effective carbon nanofibers (CNFs) in form of interconnected porous network structure were used as nanofillers. Processing, microstructure and mechanical properties of carbon nanofibers reinforced polydimethylsiloxane (PDMS) have been studied. Mechanical measurements on the composites show that the CNF-PDMS interfacial bonding can be until failure, interfacial debonding happens in the CNF-PDMS composites and the resulted permanent deformation stabilizes with increasing load-unload cycles with significant energy dissipation. PMID:21456144

  18. Genotoxicity of carbon nanofibers: Are they potentially more or less dangerous than carbon nanotubes or asbestos?

    International Nuclear Information System (INIS)

    The production of carbon nanofibers and nanotubes (CNF/CNT) and their composite products is increasing globally. CNF are generating great interest in industrial sectors such as energy production and electronics, where alternative materials may have limited performance or are produced at a much higher cost. However, despite the increasing industrial use of carbon nanofibers, information on their potential adverse health effects is limited. In the current study, we examine the cytotoxic and genotoxic potential of carbon-based nanofibers (Pyrograf (registered) -III) and compare this material with the effects of asbestos fibers (crocidolite) or single-walled carbon nanotubes (SWCNT). The genotoxic effects in the lung fibroblast (V79) cell line were examined using two complementary assays: the comet assay and micronucleus (MN) test. In addition, we utilized fluorescence in situ hybridization to detect the chromatin pan-centromeric signals within the MN indicating their origin by aneugenic (chromosomal malsegregation) or clastogenic (chromosome breakage) mechanisms. Cytotoxicity tests revealed a concentration- and time-dependent loss of V79 cell viability after exposure to all tested materials in the following sequence: asbestos > CNF > SWCNT. Additionally, cellular uptake and generation of oxygen radicals was seen in the murine RAW264.7 macrophages following exposure to CNF or asbestos but not after administration of SWCNT. DNA damage and MN induction were found after exposure to all tested materials with the strongest effect seen for CNF. Finally, we demonstrated that CNF induced predominately centromere-positive MN in primary human small airway epithelial cells (SAEC) indicating aneugenic events. Further investigations are warranted to elucidate the possible mechanisms involved in CNF-induced genotoxicity.

  19. Genotoxicity of carbon nanofibers: are they potentially more or less dangerous than carbon nanotubes or asbestos?

    Science.gov (United States)

    Kisin, E. R.; Murray, A.R.; Sargent, L.; Lowry, D.; Chirila, M.; Siegrist, K.J.; Schwegler-Berry, D.; Leonard, S.; Castranova, V.; Fadeel, B.; Kagan, V.E.; Shvedova, A.A.

    2011-01-01

    The production of carbon nanofibers and nanotubes (CNF/CNT) and their composite products is increasing globally. CNF are generating great interest in industrial sectors such as energy production and electronics, where alternative materials may have limited performance or are produced at a much higher cost. However, despite the increasing industrial use of carbon nanofibers, information on their potential adverse health effects is limited. In the current study, we examine the cytotoxic and genotoxic potential of carbon-based nanofibers (Pyrograf®-III) and compare this material with the effects of asbestos fibers (crocidolite) or single-walled carbon nanotubes (SWCNT). The genotoxic effects in the lung fibroblast (V79) cell line were examined using two complementary assays: the comet assay and micronucleus (MN) test. In addition, we utilized fluorescence in situ hybridization to detect the chromatin pan-centromeric signals within the MN indicating their origin by aneugenic (chromosomal malsegregation) or clastogenic (chromosome breakage) mechanisms. Cytotoxicity tests revealed a concentration- and time-dependent loss of V79 cell viability after exposure to all tested materials in the following sequence: asbestos>CNF>SWCNT. Additionally, cellular uptake and generation of oxygen radicals was seen in the murine RAW264.7 macrophages following exposure to CNF or asbestos but not after administration of SWCNT. DNA damage and MN induction were found after exposure to all tested materials with the strongest effect seen for CNF. Finally, we demonstrated that CNF induced predominately centromere-positive MN in primary human small airway epithelial cells (SAEC) indicating aneugenic events. Further investigations are warranted to elucidate the possible mechanisms involved in CNF-induced genotoxicity. PMID:21310169

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

  2. High performance supercapacitor based on Ni3S2/carbon nanofibers and carbon nanofibers electrodes derived from bacterial cellulose

    Science.gov (United States)

    Yu, Wendan; Lin, Worong; Shao, Xiaofeng; Hu, Zhaoxia; Li, Ruchun; Yuan, Dingsheng

    2014-12-01

    The Ni3S2 nanoparticles have been successfully grown on the carbon nanofibers (CNFs) derived from bacterial cellulose via a hydrothermal method, which the as-prepared composite exhibited high specific capacitance (883 F g-1 at 2 A g-1), much more than CNFs (108 F g-1 at 2 A g-1), and good cycle stability. The asymmetric supercapacitor was designed to contain the CNFs coated Ni3S2 nanoparticles (Ni3S2/CNFs) as positive electrode and CNFs as negative electrode in 2 M KOH electrolyte. Due to the synergistic effects of the two electrodes, asymmetric cell showed superior electrochemical performances. The optimized asymmetric supercapacitor gave a operating potential of 1.7 V in 2 M KOH aqueous solution, exhibiting a high specific capacitance of 56.6 F g-1 at 1 A g-1 and considerably high energy density of 25.8 Wh kg-1 at a power density of 425 W kg-1. Meanwhile, Ni3S2/CNFs//CNFs asymmetric supercapacitor showed excellent cycling stability with 97% specific capacitance retained after 2500 cycles.

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  5. Evaluation of Changes in Morphology and Function of Human Induced Pluripotent Stem Cell Derived Cardiomyocytes (HiPSC-CMs Cultured on an Aligned-Nanofiber Cardiac Patch.

    Directory of Open Access Journals (Sweden)

    Mahmood Khan

    Full Text Available Dilated cardiomyopathy is a major cause of progressive heart failure. Utilization of stem cell therapy offers a potential means of regenerating viable cardiac tissue. However, a major obstacle to stem cell therapy is the delivery and survival of implanted stem cells in the ischemic heart. To address this issue, we have developed a biomimetic aligned nanofibrous cardiac patch and characterized the alignment and function of human inducible pluripotent stem cell derived cardiomyocytes (hiPSC-CMs cultured on this cardiac patch. This hiPSC-CMs seeded patch was compared with hiPSC-CMs cultured on standard flat cell culture plates.hiPSC-CMs were cultured on; 1 a highly aligned polylactide-co-glycolide (PLGA nanofiber scaffold (~50 microns thick and 2 on a standard flat culture plate. Scanning electron microscopy (SEM was used to determine alignment of PLGA nanofibers and orientation of the cells on the respective surfaces. Analysis of gap junctions (Connexin-43 was performed by confocal imaging in both the groups. Calcium cycling and patch-clamp technique were performed to measure calcium transients and electrical coupling properties of cardiomyocytes.SEM demonstrated >90% alignment of the nanofibers in the patch which is similar to the extracellular matrix of decellularized rat myocardium. Confocal imaging of the cardiomyocytes demonstrated symmetrical alignment in the same direction on the aligned nanofiber patch in sharp contrast to the random appearance of cardiomyocytes cultured on a tissue culture plate. The hiPSC-CMs cultured on aligned nanofiber cardiac patches showed more efficient calcium cycling compared with cells cultured on standard flat surface culture plates. Quantification of mRNA with qRT-PCR confirmed that these cardiomyocytes expressed α-actinin, troponin-T and connexin-43 in-vitro.Overall, our results demonstrated changes in morphology and function of human induced pluripotent derived cardiomyocytes cultured in an anisotropic

  6. Aligned carbon nanotube sheet piezoresistive strain sensors

    Science.gov (United States)

    Li, Ang; Bogdanovich, Alexander E.; Bradford, Philip D.

    2015-09-01

    Carbon nanotubes (CNTs) have a unique set of properties that may be useful in the production of next generation structural health monitoring composites. This research introduces a novel CNT based material system for strain and damage sensing applications. An aligned sheet of interconnected CNTs was drawn from a chemical vapor deposition grown CNT array and then bonded to the surface of glass fiber/epoxy composite coupons. Various types of mechanical tests were conducted, accompanied by real-time electrical data acquisition, in order to evaluate the electro-mechanical behavior of the developed sensing material. Specimens were loaded in the longitudinal and transverse CNT sheet orientations to investigate the anisotropy of the piezoresistive effect. The CNT sheets exhibited good sensing stability, linearity, sensitivity and repeatability within a practical strain range; which are crucial sensor features for health monitoring. It was also demonstrated that the CNT orientation in the sheet had a dramatic effect on the sensitivity, thus validating the usefulness of this sensing material for directional strain/damage monitoring. Finally, pre-straining of the CNT sheet sensors was conducted to further enhance the linearity of electro-mechanical response and long-term stability of the sensors during cyclic loading.

  7. Plasma oxidation and stabilization of electrospun polyacrylonitrile nanofiber for carbon nanofiber formation

    Science.gov (United States)

    Hamideh Mortazavi, S.; Pilehvar, Soheil; Ghoranneviss, Mahmood; Hosseinnejad, M. T.; Zargham, Shamim; Mirarefi, Ali A.; Mirarefi, Amir Y.

    2013-11-01

    The effect of plasma treatment on the stabilization of copolymer P(AN-MA) containing 6.1 mol% methyl acrylate (MA) prepared by an electrospinning technique has been investigated at various oxygen contents (10 %, 20 % and 30 %) and different exposure times. The morphology and chemical structural evolution of electrospun and oxidized nanofibers were studied using field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). FT-IR analysis indicated that the treated nanofibers were effectively oxidized under different contents of oxygen and prolonged plasma exposure times by increasing the peak intensities of polar groups at 1730 and 3400 cm-1 corresponding to C=O stretching band and OH stretching vibration mode, respectively. Additionally, a reduction in the extent of the cyclization reaction is observed with further increase in exposure times and contents of oxygen, which implies lower conversion of C≡N bands into C=N ones in the copolymer chain. According to the FE-SEM studies, the surfaces of the treated nanofibers were completely etched after 15 min of treatment due to the existence of strong ion bombardment and a reduction in the average fiber diameters was observed.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-03-12

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

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

    Science.gov (United States)

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

    2008-03-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

  12. High-performance lithium storage in nitrogen-enriched carbon nanofiber webs derived from polypyrrole

    International Nuclear Information System (INIS)

    Highlights: • N-enriched carbon nanofiber webs are prepared via direct carbonization route with polyporrole as template. • The pyrolysis time plays an important role in N doping level and existing type. • Effect of N-doping on performance of the carbon anode material is investigated. • High reversible capacity of 238 mAh g−1 at 5 A g−1 is attained. -- Abstract: Nitrogen-doped carbon nanofiber webs (N-CNFWs) are prepared by direct pyrolyzation of polypyrrole (PPy) nanofiber webs at 600 °C. The structure and morphology of N-CNFWs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Raman spectra and elemental analysis. Both the doped N content and the N existing type in carbon, change with the pyrolysis time. As anode material for lithium-ion battery, the N-CNFWs show high capacity and good rate capability. The reversible capacity is up to 668 mAh g−1 at a current density of 0.1 A g−1 and 238 mAh g−1 at 5 A g−1, which can be ascribed to the nanofiber structure and high nitrogen content

  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. 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.

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

    Science.gov (United States)

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

    2003-01-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  18. Catalyst Activation by Microplasma for Carbon Nanofiber Synthesis in a Microreactor

    NARCIS (Netherlands)

    Agiral, Anil; Lefferts, Leon; Gardeniers, J.G.E.

    2009-01-01

    A dielectric barrier discharge is generated by flowing helium and hydrogen through a microreactor capillary which contains a coating of Ni/alumina catalyst to activate carbon nanofiber (CNF) synthesis. Optical and electrical measurements have been done to characterize the discharge during catalyst t

  19. Polyaniline-coated freestanding porous carbon nanofibers as efficient hybrid electrodes for supercapacitors

    Science.gov (United States)

    Tran, Chau; Singhal, Richa; Lawrence, Daniel; Kalra, Vibha

    2015-10-01

    Three-dimensional, free-standing, hybrid supercapacitor electrodes combining polyaniline (PANI) and porous carbon nanofibers (P-CNFs) were fabricated with the aim to integrate the benefits of both electric double layer capacitors (high power, cyclability) and pseudocapacitors (high energy density). A systematic investigation of three different electropolymerization techniques, namely, potentiodynamic, potentiostatic, and galvanostatic, for electrodeposition of PANI on freestanding carbon nanofiber mats was conducted. It was found that the galvanostatic method, where the current density is kept constant and can be easily controlled facilitates conformal and uniform coating of PANI on three-dimensional carbon nanofiber substrates. The electrochemical tests indicated that the PANI-coated P-CNFs exhibit excellent specific capacitance of 366 F g-1 (vs. 140 F g-1 for uncoated porous carbon nanofibers), 140 F cm-3 volumetric capacitance, and up to 2.3 F cm-2 areal capacitance at 100 mV s-1 scan rate. Such excellent performance is attributed to a thin and conformal coating of PANI achieved using the galvanostatic electrodeposition technique, which not only provides pseudocapacitance with high rate capability, but also retains the double-layer capacitance of the underlying P-CNFs.

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  1. Evidence of wettability variation on carbon nanofiber layers grown on oxidized silicon substrates

    NARCIS (Netherlands)

    Nair, H.; Tiggelaar, R.M.; Thakur, D.B.; Gardeniers, J.G.E.; Houselt, van A.; Lefferts, L.

    2013-01-01

    This paper describes how layers of carbon nanofibers (CNFs) with a controllable wettability can be synthesized by means of thermal catalytic chemical vapor deposition on nickel-based thin films on oxidized silicon supports. In order to achieve well-adhesive CNF-layers with a uniform surface coverage

  2. Supercapacitor Electrodes Based on High-Purity Electrospun Polyaniline and Polyaniline-Carbon Nanotube Nanofibers.

    Science.gov (United States)

    Simotwo, Silas K; DelRe, Christopher; Kalra, Vibha

    2016-08-24

    Freestanding, binder-free supercapacitor electrodes based on high-purity polyaniline (PANI) nanofibers were fabricated via a single step electrospinning process. The successful electrospinning of nanofibers with an unprecedentedly high composition of PANI (93 wt %) was made possible due to blending ultrahigh molecular weight poly(ethylene oxide) (PEO) with PANI in solution to impart adequate chain entanglements, a critical requirement for electrospinning. To further enhance the conductivity and stability of the electrodes, a small concentration of carbon nanotubes (CNTs) was added to the PANI/PEO solution prior to electrospinning to generate PANI/CNT/PEO nanofibers (12 wt % CNTs). Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) porosimetry were conducted to characterize the external morphology of the nanofibers. The electrospun nanofibers were further probed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The electroactivity of the freestanding PANI and PANI/CNT nanofiber electrodes was examined using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Competitive specific capacitances of 308 and 385 F g(-1) were achieved for PANI and PANI-CNT based electrodes, respectively, at a current density of 0.5 A g(-1). Moreover, specific capacitance retentions of 70 and 81.4% were observed for PANI and PANI-CNT based electrodes, respectively, after 1000 cycles. The promising electrochemical performance of the fabricated electrodes, we believe, stems from the porous 3-D electrode structure characteristic of the nonwoven interconnected nanostructures. The interconnected nanofiber network facilitates efficient electron conduction while the inter- and intrafiber porosity enable excellent electrolyte penetration within the polymer matrix, allowing fast ion transport to the active sites. PMID:27467445

  3. Self-heating function of carbon nanofiber cement pastes

    Directory of Open Access Journals (Sweden)

    Galao, O.

    2014-05-01

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

  4. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    Science.gov (United States)

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF. PMID:25595622

  5. 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.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

  8. 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.

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

    Science.gov (United States)

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

    2015-03-01

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

  10. The Optical Excitation of Zigzag Carbon Nanotubes with Photons Guided in Nanofibers

    CERN Document Server

    Broadfoot, S; Jaksch, D

    2011-01-01

    We consider the excitation of electrons in semiconducting carbon nanotubes by photons from the evanescent field created by a subwavelength-diameter optical fiber. The strongly changing evanescent field of such nanofibers requires dropping the dipole approximation. We show that this leads to novel effects, especially a high dependence of the photon absorption on the relative orientation and geometry of the nanotube-nanofiber setup in the optical and near infrared domain. In particular, we calculate photon absorption probabilities for a straight nanotube and nanofiber depending on their relative angle. Nanotubes orthogonal to the fiber are found to perform much better than parallel nanotubes when they are short. As the nanotube gets longer the absorption of parallel nanotubes is found to exceed the orthogonal nanotubes and approach 100% for extremely long nanotubes. In addition, we show that if the nanotube is wrapped around the fiber in an appropriate way the absorption is enhanced. We find that optical and ne...

  11. Carbon Nanotubes-Adsorbed Electrospun PA66 Nanofiber Bundles with Improved Conductivity and Robust Flexibility.

    Science.gov (United States)

    Guan, Xiaoyang; Zheng, Guoqiang; Dai, Kun; Liu, Chuntai; Yan, Xingru; Shen, Changyu; Guo, Zhanhu

    2016-06-01

    Electrospun polyamide (PA) 66 nanofiber bundles with high conductivity, improved strength, and robust flexibility were successfully manufactured through simply adsorbing multiwall carbon nanotubes (MWNTs) on the surface of electrospun PA66 nanofibers. The highest electrical conductivity (0.2 S/cm) and tensile strength (103.3 MPa) were achieved for the bundles immersed in the suspension with 0.05 wt % MWNTs, indicating the formation of conductive network from adsorbed MWNTs on the surface of PA66 nanofibers. The decrease of porosity for the bundles immersed in the MWNT dispersion and the formation of hydrogen bond between PA66 nanofibers and MWNTs suggest a superb interfacial interaction, which is responsible for the excellent mechanical properties of the nanocomposite bundles. Furthermore, the resistance fluctuation under bending is less than 3.6%, indicating a high flexibility of the nanocomposite bundles. The resistance of the nanocomposite bundle had a better linear dependence on the temperature applied between 30 and 150 °C. More importantly, such highest working temperature of 150 °C far exceeded that of other polymer-based temperature sensors previously reported. This suggests that such prepared MWNTs-adsorbed electrospun PA66 nanofiber bundles have great potentials in high temperature detectors. PMID:27172292

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huan; Xu, Bin; Jia, Mengqiu, E-mail: jiamq@mail.buct.edu.cn; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-30

    Highlights: • The composites of polyaniline nanofiber and large mesoporous carbon were prepared for supercapacitors. • The large mesoporous carbons were simply prepared by nano-CaCO{sub 3} template method. • The composites exhibit high capacitance and good rate capability and cycle stability. - Abstract: A composite of polyaniline nanofiber/large mesoporous carbon (PANI-F/LMC) hybrid was prepared by an in situ chemical oxidative polymerization of aniline monomer with nano-CaCO{sub 3} templated LMC as host matrix for supercapacitors. The morphology, composition and electronic structure of the composites (PANI-F/LMC) together with pure PANI nanofibers and the LMC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the PANI nanofibers were incorporated into the large mesochannels of LMC with interpenetrating framework formed. Such unique structure endows the PANI-F/LMC composite with a high capacitance of 473 F g{sup −1} at a current load of 0.1 A g{sup −1} with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  14. 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. PMID:24296569

  15. 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.

  16. 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/Ni nanopar......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....../Ni nanoparticles, devoid of any gaseous carbon source and external heating and stimulated by an electron beam in a 300 kilo volt transmission electron microscope....

  17. Ruthenium catalyst on carbon nanofiber support layers for use in silicon-based structured microreactors, Part I: Preparation and characterization

    NARCIS (Netherlands)

    Thakur, D.B.; Tiggelaar, R.M.; Hoang, T.M.C.; Gardeniers, J.G.E.; Lefferts, L.; Seshan, K.

    2011-01-01

    The preparation and characterization of ruthenium catalytic nanoparticles on carbon nanofiber (CNF) support layers via homogeneous deposition precipitation (HDP) and pulsed laser deposition (PLD) is presented. Prior to ruthenium deposition the CNF layers were functionalized via liquid phase oxidatio

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

    Science.gov (United States)

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

    A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450 °C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium. PMID:23794416

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

    Science.gov (United States)

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

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

  20. Growth and characterization of aligned ultralong and diameter-controlled silicon nanotubes by hot wire chemical vapor deposition using electrospun poly(vinyl pyrrolidone) nanofiber template

    Science.gov (United States)

    Zhou, Ming; Li, Ruishan; Zhou, Jinyuan; Guo, Xiaosong; Liu, Bin; Zhang, Zhenxing; Xie, Erqing

    2009-12-01

    Using aligned suspended polyvinyl pyrrolidone nanofibers array as template, aligned ultralong (about 4 mm) silicon nanotubes have been prepared by a hot wire chemical vapor deposition process. Scanning electron microscopy and transmission electron microscopy demonstrate that the inner diameter (35-200 nm) and wall thickness (20-400 nm) of Si tubes are controlled, respectively, by baking the electrospun nanofibers and by coating time. The tube wall is composed of nanoparticle or nanopillar, and the inner surface of the wall is smoother than the outer surface of the wall. The microphotoluminescence spectra of the thinner Si nanotubes show three light emission bands in the red, green, and blue regions. And the luminescence mechanism is explained according to the quantum-confinement-luminescence center process and radiative recombination from the defect centers.

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

    Institute of Scientific and Technical Information of China (English)

    徐东升; 郭国霖; 桂琳琳; 唐有祺; 施祖进; 金朝霞; 顾振南

    2000-01-01

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

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

    Science.gov (United States)

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

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

  3. Carbon-Encapsulated Hollow Porous Vanadium-Oxide Nanofibers for Improved Lithium Storage Properties.

    Science.gov (United States)

    An, Geon-Hyoung; Lee, Do-Young; Ahn, Hyo-Jin

    2016-08-01

    Carbon-encapsulated hollow porous vanadium-oxide (C/HPV2O5) nanofibers have been fabricated using electrospinning and postcalcination. By optimized postcalcination of vanadium-nitride and carbon-nanofiber composites at 400 °C for 30 min, we synthesized a unique architecture electrode with interior void spaces and well-defined pores as well as a uniform carbon layer on the V2O5 nanofiber surface. The optimized C/HPV2O5 electrode postcalcined at 400 °C for 30 min showed improved lithium storage properties with high specific discharge capacities, excellent cycling durability (241 mA h g(-1) at 100 cycles), and improved high-rate performance (155 mA h g(-1) at 1000 mA g(-1)), which is the highest performance in comparison with previously reported V2O5-based cathode materials. The improved electrochemical feature is due to the attractive properties of the carbon-encapsulated hollow porous structure: (I) excellent cycling durability with high specific capacity relative to the adoption of carbon encapsulation as a physical buffer layer and the effective accommodation of volume changes due to the hollow porous structure, (II) improved high-rate performance because of a shorter Li-ion diffusion pathway resulting from interior void spaces and well-defined pores at the surface. This unique electrode structure can potentially provide new cathode materials for high-performance lithium-ion batteries. PMID:27404906

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  6. Aligning carbon fibers in micro-extruded composite ink

    Science.gov (United States)

    Mahajan, Chaitanya G.

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Jiapeng Fu

    2014-02-01

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

  9. 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.

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

    International Nuclear Information System (INIS)

    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 (H2S) adsorption at 300 °C. Breakthrough experiments with the ZnO/CNF composite containing 25.7 wt% of ZnO for H2S 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

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

    Science.gov (United States)

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

    2016-11-01

    The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C3N4/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C3N4/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C3N4/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules. PMID:27239724

  12. Stainless Steel Mesh Supported Carbon Nanofibers for Electrode in Bioelectrochemical System

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2016-01-01

    Full Text Available We proposed a self-connected carbon nanofiber design for electrode in microbial bioelectrochemical system. This design was realized by direct growth of carbon nanofibers (CNFs onto stainless steel (SSM via a chemical vapor deposition process without addition of any external catalysts. In the CNFs-SSM composite electrode, the SSM acted as the conductive network and ensured efficient substrate and proton transfer, and the CNFs layer served as highly porous habitats for thick biofilm propagation. The current generated by the CNFs-SSM was 200 times higher than the bare SSM under the same experimental conditions. This provided a simple and promising method for preparation of electrode material with high performance and low-cost in bioelectrochemical system.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-15

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

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

    Science.gov (United States)

    Basaldua, Daniel Thomas

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

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

    CERN Document Server

    Licht, Stuart

    2015-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Li-hua TENG; Tian-di TANG

    2008-01-01

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

  17. Carbon nanofiber aerogels for emergent cleanup of oil spillage and chemical leakage under harsh conditions

    OpenAIRE

    Zhen-Yu Wu; Chao Li; Hai-Wei Liang; Yu-Ning Zhang; Xin Wang; Jia-Fu Chen; Shu-Hong Yu

    2014-01-01

    To address oil spillage and chemical leakage accidents, the development of efficient sorbent materials is of global importance for environment and water source protection. Here we report on a new type of carbon nanofiber (CNF) aerogels as efficient sorbents for oil uptake with high sorption capacity and excellent recyclability. Importantly, the oil uptake ability of the CNF aerogels can be maintained over a wide temperature range, from liquid nitrogen temperature up to ca. 400°C, making them ...

  18. Benzoylation of anisole catalyzed by Ga/SBA-15 supported on carbon nanofibers composite

    OpenAIRE

    EL BERRICHI, F. Z.; Pham-Huu, C.; CHERIF, L.; Louis, B; M. J.; Ledoux

    2011-01-01

    Carbon nanofiber composite (C-NFC) shows several advantages compared to the conventional supports which are usually employed in catalysis such as alumina, silica or activated charcoal. In this present work we have developed a new hybrid catalyst consisting of SBA-15 supported on C-NFC for the benzoylation reaction. The structured materials allow an important improvement of the reaction hydrodynamics and favor the mass transfer between the active phase and the reactants, especially in the liqu...

  19. How do vapor grown carbon nanofibers nucleate and grow from deoiled asphalt?

    International Nuclear Information System (INIS)

    Research highlights: → A modified growth mechanism of carbon nanofibers was proposed. → Growth process includes (1) pyrolysis and aggregation, (2) nucleation, coalescence and self-assembly and (3) deveplopment and maturation. → The nucleation and rearrangement of graphitic layers depend on the crystal orientation of the metal nanoparticles. - Abstract: During the experiments aimed at understanding the evolution mechanism by which vapor grown carbon nanofibers (VGCNFs) nucleate and grow, a series of carbon nanomaterials were synthesized by chemical vapor deposition (CVD) using deoiled asphalt (DOA) as carbon source and ferrocene as catalyst precursor with an experimental strategy developed to quench the CVD at different deposition times (3-30 min). The morphology and microstructure of the products were investigated by field emission scanning electron microscope, high resolution transmission electron microscope and X-ray powder diffractometer. The formation of hollow/metal-encapsulating carbon nanoparticles at short deposition time (3 min) of CVD and the subsequent evolution of these nanoparticles into carbon nanotubes/nanofibers at longer deposition time suggest a multi-step growth model for VGCNFs, which includes the stages of (1) pyrolysis and aggregation, (2) nucleation, coalescence and self-assembly, and (3) development and maturation. At first, C, Fe and Fe/C clusters are produced by decomposition and agglomeration of C and Fe species from the pyrolysis of DOA and ferrocene; second, the carbon nanoparticles are self-assembled into nanowires with dispersive metal nanoparticles, which are further developed into nanotubes for structural stability and minimum surface energy, meanwhile fishbone-like CNFs might be formed by rearranging carbon layers at an angle against the tube axis under the nucleation of small graphitic layers on certain crystal orientation of the metal particles; finally, CNFs are formed by the synergistic action of metal catalysis and

  20. Curvature aided efficient axial field emission from carbon nanofiber-reduced graphene oxide superstructures on tungsten wire substrate

    Science.gov (United States)

    Jha, Arunava; Roy, Rajarshi; Sen, Dipayan; Chattopadhyay, Kalyan K.

    2016-03-01

    Field emission characteristics found in reduced graphene oxide (RGO) and RGO based composite systems have always been an area of research interest mainly due to presence of prolific quasi aligned edges working as emitter sites. However, the specific role and extent of edge curvature geometry in RGO systems in regards to the enhancement of field emission has not discussed thoroughly prior to this work. In this work we demonstrate enhanced axial field emission due to top assembly of thin RGO layer over a quasi-vertically aligned carbon nanofiber thin film supported on a tungsten wire substrate. Furthermore, simulation analysis for our RGO based hybrid system using finite element modeling showed that two-stage local field amplification in RGO is responsible for the overall improvement of field emission characteristics. In support of our findings, a tentative explanation has been proposed based on the additional emission from RGO edges in between the CNF network resulting to the enhancement of axial field emission in the nanocomposite superstructure.

  1. Fabrication of Dense Horizontally Aligned Arrays of Single-Wall Carbon Nanotubes from Vertically Aligned Arrays

    Science.gov (United States)

    Zheng, Gang; Wang, Xueshen; Li, Qunqing; Xie, Jing; Zhu, Zhendong; Zou, Yuan; Liu, Junku; Jiang, Kaili; Fan, Shoushan

    2011-01-01

    The as-grown vertically aligned single-wall carbon nanotube (SWNT) arrays are transferred from the original silicon substrate to a poly(ethylene terephthalate) (PET) substrate, which acts as a stamp. Thin SWNT films can be applied from the stamp to the target substrate and subsequently treated by an ultrasonic process to reduce their thickness to 6.6 nm. The transferred SWNT thin film retains the advantageous super-alignment and high-density properties of the vertical SWNT arrays. The linear density, transmittance, and square resistance of the thin film are as high as 15 tubes per micrometer, 99% at 550 nm, and 16 kΩ, respectively.

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

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHOU Ming; MA Weiwei; CAI Lan

    2009-01-01

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

  3. Broadband laser polarization control with aligned carbon nanotubes

    CERN Document Server

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

    2015-01-01

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

  4. Increased Alignment in Carbon Nanotube Growth

    Science.gov (United States)

    Delzeit, Lance D. (Inventor)

    2007-01-01

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

  5. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  8. Preparation and characterization of Polyacrylonitrile/ Manganese Dioxides- based Carbon Nanofibers via electrospinning process

    Science.gov (United States)

    Che Othman, F. E.; Yusof, N.; Jaafar, J.; Ismail, A. F.; Hasbullah, H.; Abdullah, N.; Ismail, M. S.

    2016-06-01

    This research reports the production of precursor polyacrylonitrile (PAN)/ manganese dioxide (MnO2) nanofibers (NFs) via electrospinning method followed by stabilization and carbonization processes. Nowadays, electrospinning has become a suitable method in manufacturing continuous NFs, thus it is employed to fabricate NFs in this study. The microstructural properties and adsorption competencies of the produced NFs were also studied. The NFs were prepared by electrospinning the polymer solution of Polyacrylonitrile (PAN) and Manganese Dioxide (MnO2) in, N, N-Dimethylformamide (DMF) solvent. The factors considered in this study were various polymer PAN/MnO2 concentrations which will significantly affect the specific surface area, fiber morphology and the diameter of the NFs prepared. Subsequently, heat treatment is applied by setting up the stabilization temperature at 275 °C and carbonization temperature at 800 °C with constant dwelling time (30 min). Nitrogen gas at constant rate 0.2 L/min was used for stabilization and carbonization with the stabilization rate (2 °C/min) and carbonization rate (5 °C/min). The carbon nanofibers (CNFs) produced were characterized using Scanning Electron Microscopy (SEM), Brunauer Emmett and Teller (BET) surface area and Fourier Transmission Infrared Spectroscopy (FTIR). It was found that the PAN/MnO2 CNFs were successfully produced with the carbonization temperature of 800 °C. The prepared PAN/MnO2 CNFs prepared showed an enhanced in specific surface area about two times compared to it precursor NFs.

  9. 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. PMID:26459170

  10. 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.

  11. NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications

    OpenAIRE

    Dawei Li; Pengfei Lv; Jiadeng Zhu; Yao Lu; Chen Chen; Xiangwu Zhang; Qufu Wei

    2015-01-01

    NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical propertie...

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

    Institute of Scientific and Technical Information of China (English)

    Behnaz BAKHSHANDEH; Masoud SOLEIMANI; Nasser GHAEMI; Iman SHABANI

    2011-01-01

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

  13. Dynamics of carbon nanotube alignment by electric fields

    International Nuclear Information System (INIS)

    The dynamics of multiwall carbon nanotube (MWCNT) alignment inside viscous media using electric fields is investigated. Electrical current measurements were performed in situ during the application of an electric field to liquid solutions of deionized water or dissolved polymer containing MWCNTs. The variation of electrical current over time was associated to the dynamics of the MWCNT network formation. The influence of the electric field magnitude and frequency on the MWCNT network formation was studied. MWCNT migration towards the negative electrode was observed when a direct current electric field was applied, whereas formation of an aligned MWCNT network was achieved for an alternating current electric field. The increase of the electric field frequency promotes a faster formation of an aligned MWCNT network and thinner MWCNT bundles. A higher viscosity of the liquid medium yields slower MWCNT alignment evidenced by a slower change of electrical current through the viscous system. An analytical model based on the dielectrophoresis-induced torque, which considers the viscosity of the medium, is also proposed to explain the dynamics of MWCNT alignment. Furthermore, aligned MWCNT/polysulfone solid composites were fabricated and electrically characterized. The solid composites presented anisotropic electrical conductivity, which was more evident for low MWCNT concentrations (0.1–0.2 wt%). (paper)

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

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: • Flexible Si/SiO2/C composite nanofibers were introduced as Li–ion battery anodes. • SiO2 component of composite nanofibers facilitated the high flexibility. • Flexible Si/SiO2/C composite nanofibers were coated with CVD-carbon. • CVD carbon coating and SiO2 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/SiO2/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/SiO2/C nanofibers was performed by CVD technique. Electrochemical performance results showed that CVD carbon-coated flexible Si/SiO2/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/SiO2/C nanofiber composites are promising anode material candidate for next-generation flexible and high-energy lithium–ion batteries

  15. Self-sustained thin webs consisting of porous carbon nanofibers for supercapacitors via the electrospinning of polyacrylonitrile solutions containing zinc chloride

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.; Ngoc, B.T.N.; Yang, K.S. [Center for Functional Nano Fine Chemicals, Chonnam National University, 300 Yong-bond dong, Buk-gu, Gwangju 500-757 (Korea); Kojima, M.; Kim, Y.A.; Kim, Y.J.; Endo, M. [Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano-shi 380-8553 (Japan); Yang, S.C. [AMOTECH Co., Ltd, 597-2 Wonsanri, Hasungmyun, Gimpo, Gyunggido (Korea)

    2007-09-03

    We present a simple strategy for the fabrication of porous carbon nanofibers (see figure). This procedure produces thin webs by electrospinning a polymer solution containing different concentrations of zinc chloride and subsequently thermally treating the system. Their resulting surface area and good electrical conductivity make these porous carbon nanofibers useful in the fabrication of efficient electrodes for supercapacitors. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  16. 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.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

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

    Science.gov (United States)

    Kaerkitcha, Navaporn; Chuangchote, Surawut; Sagawa, Takashi

    2016-12-01

    Hollow carbon nanofibers (HCNFs) were prepared by electrospinning method with several coaxial nozzles, in which the level of the inner nozzle-end is adjustable. Core/shell nanofibers were prepared from poly(methyl methacrylate) (PMMA) as a pyrolytic core and polyacrylonitrile (PAN) as a carbon shell with three types of normal (viz. inner and outer nozzle-ends are balanced in the same level), inward, and outward coaxial nozzles. The influence of the applied voltage on these three types of coaxial nozzles was studied. Specific surface area, pore size diameter, crystallinity, and degree of graphitization of the hollow and mesoporous structures of carbon nanofibers obtained after carbonization of the as spun PMMA/PAN nanofibers were characterized by BET analyses, X-ray diffraction, and Raman spectroscopy in addition to the conductivity measurements. It was found that specific surface area, crystallinity, and graphitization degree of the HCNFs affect the electrical conductivity of the carbon nanofibers. PMID:27067734

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-30

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

  2. 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.

  3. Fabrication and electron field-emission of carbon nanofibers grown on silicon nanoporous pillar array

    International Nuclear Information System (INIS)

    Highlights: ► Carbon nanofibers were grown on silicon nanoporous pillar array by a CVD method.► Low turn-on field, high density and stable FE current were obtained in CNTs/Si-NPA.► Defects in CNTs and Si array substrate contributes the excellent FE property. - Abstract: Random orientation carbon nanofibers (CNFs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition (CVD) method with acetylene (C2H2) as carbon precursor and Ni as the catalyst. The synthesized CNFs were mainly composed of amorphous carbon and disordered graphite layers with a core–shell like structure. And, the tangled CNFs and the regular silicon-pillar array formed a nanometer-micron hierarchy structure. The electron field-emission (FE) property of CNFs/Si-NPA was measured and low turn-on field, high-density and stable FE current, high enhancement factor were obtained. The outstanding FE performance of the CNFs/Si-NPA emitters was attributed to the random orientation and defects of CNFs, the undulate surface of the Si-NPA substrate.

  4. Preparation of macroporous carbon nanofibers with macroscopic openings in the surfaces and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungwon; Moon, Geon Dae; Jeong, Unyong [Department of Materials Science and Engineering, Yonsei Universivty, 134 Shinchon-dong, Seoul (Korea, Republic of); Lee, Kipoong; Kim, Young-Rok [Institute of Life Sciences and Resources and Department of Food Science and Biotechnology, Kyung Hee University, Yongin (Korea, Republic of); Won, Yong Sun; Yoon, Yeo-Joo; Park, Sung Soo, E-mail: ujeong@yonsei.ac.k [Corporate R and D Institute, Samsung Electro-Mechanics, 314 Maetan 3-Dong, Yeongtong-Gu, Suwon, Gyunggi-Do (Korea, Republic of)

    2009-11-04

    Macroporous carbon nanofibers with mesoscale surface openings were produced by electrospinning. During the electrospinning of polyacrylonitrile (PAN) solution including crosslinked polymer colloids, the polymer colloids were concentrated in the center of PAN fibers. Carbonization left interconnected spherical pores inside the carbon fibers and mesoscale openings in the fiber surfaces. The existence of surface openings facilitated inward diffusion of various solvent molecules, nanoparticles, and large molecules such as proteins. The porous fibers could be dispersed in both hydrophilic and hydrophobic solvents and materials, which enabled production of polymer composites in which the fibers and polymers were interpenetrating through the pores. Silica coating on the macroporous carbon fibers enriched the surface chemistry to effectively immobilize proteins helped by easy diffusion through surface openings.

  5. Preparation of very long and open aligned carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

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

    2000-01-01

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

  6. Durability of Carbon Nanofiber (CNF) & Carbon Nanotube (CNT) as Catalyst Support for Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Borghei, Maryam; Lund, Peter;

    2013-01-01

    (normally carbon black) is one of the essential degradation mechanisms during cell operation. In this work, durability of Carbon Nanofibers (CNF) & Carbon Nanotubes (CNT) as alternative platinum catalyst supports for Proton Exchange Membrane Fuel Cells (PEMFCs) was assessed. Platinized CNF and CNT using...... a standard polyol method were prepared and fabricated as cathodes of Membrane Electrode Assemblies (MEA) for PEMFC. Both the catalysts as such and the MEAs made out of them were evaluated regarding to thermal and electrochemical stability using traditional carbon black (Vulcan XC72) as a reference. Thermal...... gravimetric analysis (TGA), cyclic voltammetry (CV), polarization curve and impedance spectroscopy were applied on the samples under accelerated stress conditions. The carbon nano-materials demonstrated better stability as support for nano-sized platinum catalyst under PEMFC related operating conditions. Due...

  7. Mechanism of Carbon Nanotubes Aligning along Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    MA Shao-Jie; GUO Wan-Lin

    2008-01-01

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

  8. Fabrication and Experimental Analysis of Axially Oriented Nanofibers.

    Science.gov (United States)

    Aphale, Ashish N; Mahakalkar, Kapil; Macwan, Isaac G; Mukerji, Ishita; Cox, Paris J; Mahapatra, Manoj; Singh, Prabhakar; Ajayan, Pulickel M; Patra, Prabir K

    2016-03-01

    A novel design of a laboratory built axially rotating collector (ARC) having capability to align electrospun nanofibers have been described. A detailed morphological comparison of such nanofibers orientation and their geometry is done using scanning electron microscopy (SEM). For comparison various polymeric solutions were electrospun on conventional static collector as well as ARC. The average diameter of polyvinyl alcohol (PVA) nanofibers was found to be 250 nm while polycaprolactone (PCL) nanofibers were found to be within a range of 600-800 nm. Conducting nanoparticles such as graphene and multi-walled carbon nanotubes (MWNTs) mixed with polymer solutions shown to have a significant influence on the overall geometry of these nanofibers and their diameter distribution. It is evident from the SEM analysis that both graphene and MWNTs in polymer solution play a crucial role in achieving a uniform diameter of nanofibers. Lastly, the formation of the aligned nanofibers using ARC has been mathematically modeled and the electromagnetic field governing the process has been simulated. PMID:27455687

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

    Science.gov (United States)

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

    2010-06-01

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

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

    OpenAIRE

    Seok-Hwan Park; Wan-Jin Lee

    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-s...

  11. CdS loaded on coal based activated carbon nanofibers with enhanced photocatalytic property

    Science.gov (United States)

    Guo, Jixi; Guo, Mingxi; Jia, Dianzeng; Song, Xianli; Tong, Fenglian

    2016-08-01

    The coal based activated carbon nanofibers (CBACFs) were prepared by electrospinning a mixture of polyacrylonitrile (PAN) and acid treated coal. Cadmium sulfide (CdS) nanoparticles loaded on CBACFs were fabricated by solvothermal method. The obtained samples were characterized by FESEM, TEM, and XRD. The results reveal that the CdS nanoparticles are homogeneously dispersed on the surfaces of CBACFs. The CdS/CBACFs nanocomposites exhibited higher photoactivity for photodegradation of methyl blue (MB) under visible light irradiation than pure CdS nanoparticles. CBACFs can be used as low cost support materials for the preparation of nanocomposites with high photocatalytic activity.

  12. Fabrication of Ni-B alloy coated vapor-grown carbon nanofibers by electroless deposition

    OpenAIRE

    Arai, Susumu; Imoto, Yuzo; Suzuki, Yosuke; Endo, Morinobu

    2011-01-01

    Ni-B alloy coated vapor-grown carbon nanofibers (VGCNFs) were fabricated by electroless deposition and their microstructures were investigated. The effects of heat treatment on the coated VGCNFs were also studied. VGCNFs could be coated with a homogeneous Ni-B alloy film using a plating bath containing dimethylaminoborane (DMAB) as a reducing agent. The boron content of the Ni-B alloy film could be varied from 14 to 24 atom% B by varying the DMAB concentration of the plating bath. The VGCNFs ...

  13. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

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

    OpenAIRE

    Xiaoxiao Hou; Liqun Zhang; Sizhu Wu; Zhenyu Song

    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 mi...

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

    Science.gov (United States)

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

    2016-10-01

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

  17. Fabrication of Nerve Growth Factor Encapsulated Aligned Poly(ε-Caprolactone Nanofibers and Their Assessment as a Potential Neural Tissue Engineering Scaffold

    Directory of Open Access Journals (Sweden)

    Jue Hu

    2016-02-01

    Full Text Available Peripheral nerve injury is a serious clinical problem to be solved. There has been no breakthrough so far and neural tissue engineering offers a promising approach to promote the regeneration of peripheral neural injuries. In this study, emulsion electrospinning technique was introduced as a flexible and promising technique for the fabrication of random (R and aligned (A Poly(ε-caprolactone (PCL-Nerve Growth Factor (NGF&Bovine Serum Albumin (BSA nanofibrous scaffolds [(R/A-PCL-NGF&BSA], where NGF and BSA were encapsulated in the core while PCL form the shell. Random and aligned pure PCL, PCL-BSA, and PCL-NGF nanofibers were also produced for comparison. The scaffolds were characterized by Field Emission Scanning Electron Microscopy (FESEM and water contact angle test. Release study showed that, with the addition of stabilizer BSA, a sustained release of NGF from emulsion electrospun PCL nanofibers was observed over 28 days. [3-(4,5-dimethylthiazol-2-yl-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl-2H-tetrazolium, inner salt; MTS] assay revealed that (R/A-PCL-NGF and (R/A-PCL-NGF&BSA scaffolds favored cell growth and showed no cytotoxicity to PC12 cells. Laser scanning confocal microscope images exhibited that the A-PCL-NGF&BSA scaffold increased the length of neurites and directed neurites extension along the fiber axis, indicating that the A-PCL-NGF&BSA scaffold has a potential for guiding nerve tissue growth and promoting nerve regeneration.

  18. 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

  19. 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.

  20. Ultralight anisotropic foams from layered aligned carbon nanotube sheets

    Science.gov (United States)

    Faraji, Shaghayegh; L. Stano, Kelly; Yildiz, Ozkan; Li, Ang; Zhu, Yuntian; Bradford, Philip D.

    2015-10-01

    In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm-3, the foam structure is over 500 times less dense than bulk graphite. Microscopy revealed that PyC coated the junctions among CNTs, and also increased CNT surface roughness. These changes in the morphology explain the transition from inelastic behavior to foam-like recovery of the layered CNT sheet structure. Mechanical and thermal properties of the foams were tuned for different applications through variation of PyC deposition duration while dynamic mechanical analysis showed no change in mechanical properties over a large temperature range. Observation of a large and linear electrical resistance change during compression of the aligned CNT/carbon (ACNT/C) foams makes strain/pressure sensors a relevant application. The foams have high oil absorption capacities, up to 275 times their own weight, which suggests they may be useful in water treatment and oil spill cleanup. Finally, the ACNT/C foam's high porosity, surface area and stability allow for demonstration of the foams as catalyst support structures.In this work, we present large scale, ultralight aligned carbon nanotube (CNT) structures which have densities an order of magnitude lower than CNT arrays, have tunable properties and exhibit resiliency after compression. By stacking aligned sheets of carbon nanotubes and then infiltrating with a pyrolytic carbon (PyC), resilient foam-like materials were produced that exhibited complete recovery from 90% compressive strain. With density as low as 3.8 mg cm-3, the foam structure is over 500 times less dense than

  1. 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.

  2. Microwave conductance of aligned multiwall carbon nanotube textile sheets

    Science.gov (United States)

    Brown, Brian L.; Bykova, Julia S.; Howard, Austin R.; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2014-12-01

    Multiwall carbon nanotube (MWNT) sheets are a class of nanomaterial-based multifunctional textile with potentially useful microwave properties. To understand better the microwave electrodynamics, complex AC conductance measurements from 0.01 to 50 GHz were made on sheets of highly aligned MWNTs with the alignment texture both parallel and perpendicular to the microwave electric field polarization. In both orientations, the AC conductance is modeled to first order by a parallel frequency-independent conductance and capacitance with no inductive contribution. This is consistent with low-frequency diffusive Drude AC conduction up to 50 GHz, in contrast to the "universal disorder" AC conduction reported in many types of single-wall nanotube materials.

  3. 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.

  4. Superhydrophobic and conductive carbon nanofiber/PTFE composite coatings for EMI shielding.

    Science.gov (United States)

    Das, Arindam; Hayvaci, Harun T; Tiwari, Manish K; Bayer, Ilker S; Erricolo, Danilo; Megaridis, Constantine M

    2011-01-01

    This paper presents a solvent-based, mild method to prepare superhydrophobic, carbon nanofiber/PTFE-filled polymer composite coatings with high electrical conductivity and reports the first data on the effectiveness of such coatings as electromagnetic interference (EMI) shielding materials. The coatings are fabricated by spraying dispersions of carbon nanofibers and sub-micron PTFE particles in a polymer blend solution of poly(vinyledene fluoride) and poly(methyl methacrylate) on cellulosic substrates. Upon drying, coatings display static water contact angles as high as 158° (superhydrophobic) and droplet roll-off angles of 10° indicating self-cleaning ability along with high electrical conductivities (up to 309 S/m). 100 μm-thick coatings are characterized in terms of their EMI shielding effectiveness in the X-band (8.2-12.4 GHz). Results show up to 25 dB of shielding effectiveness, which changed little with frequency at a fixed composition, thus indicating the potential of these coatings for EMI shielding applications and other technologies requiring both extreme liquid repellency and high electrical conductivity. PMID:20889160

  5. Touch- and Brush-Spinning of Nanofibers.

    Science.gov (United States)

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

    2015-11-01

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

  6. 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.

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

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  9. Influence of base strength on the catalytic performance of nano-sized alkaline earth metal oxides supported on carbon nanofibers

    NARCIS (Netherlands)

    Frey, A.M.; Yang, J.; Feche, C.; Essayem, N.; Stellwagen, D.R.; Figueras, F.; Jong, de K.P.; Bitter, J.H.

    2013-01-01

    Nano-sized (3 nm) alkaline earth metal oxides supported on carbon nanofibers were prepared by a facile impregnation and heat treatment method of the corresponding nitrates. These supported catalysts showed a significant improved activity for the aldol reaction and transesterification compared to the

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

    NARCIS (Netherlands)

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

    2004-01-01

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

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

    Science.gov (United States)

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

    2013-04-01

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

  12. Fabrication of carbon nanofiber-driven electrodes from electrospun polyacrylonitrile/polypyrrole bicomponents for high-performance rechargeable lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Liwen; Yao, Yingfang; Toprakci, Ozan; Lin, Zhan; Liang, Yinzheng; Shi, Quan; Medford, Andrew J.; Millns, Christopher R.; Zhang, Xiangwu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, 2401 Research Drive, Raleigh, NC 27695-8301 (United States)

    2010-04-02

    Carbon nanofibers were prepared through electrospinning a blend solution of polyacrylonitrile and polypyrrole, followed by carbonization at 700 C. Structural features of electrospun polyacrylonitrile/polypyrrole bicomponent nanofibers and their corresponding carbon nanofibers were characterized using scanning electron microscopy, differential scanning calorimeter, thermo-gravimetric analysis, wide-angle X-ray diffraction, and Raman spectroscopy. It was found that intermolecular interactions are formed between two different polymers, which influence the thermal properties of electrospun bicomponent nanofibers. In addition, with the increase of polypyrrole concentration, the resultant carbon nanofibers exhibit increasing disordered structure. These carbon nanofibers were used as anodes for rechargeable lithium-ion batteries without adding any polymer binder or conductive material and they display high reversible capacity, improved cycle performance, relatively good rate capability, and clear fibrous morphology even after 50 charge/discharge cycles. The improved electrochemical performance of these carbon nanofibers can be attributed to their unusual surface properties and unique structural features, which amplify both surface area and extensive intermingling between electrode and electrolyte phases over small length scales, thereby leading to fast kinetics and short pathways for both Li ions and electrons. (author)

  13. 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

    isotherm), the ionomer has varying affinities for CNFs (Keq. = between 5 and 22) as compared to Vulcan (Keq. = 18), depending on surface treatments. However, the interactions are most likely governed by different adsorption mechanisms depending on hydrophilicity / hydrophobicity of the adsorbent carbon......A systematic adsorption study of perfluorinated sulfonic acid Nafion® ionomer on ribbon type highly graphitized carbon nanofibers (CNFs) was carried out using 19 fluorine nuclear magnetic resonance spectroscopy. Based on the values obtained for the equilibrium constant (Keq., derived from Langmuir....... The ionomer is probably adsorbed via the polar sulfonic group on hydrophilic Vulcan, whereas, it is adsorbed primarily via hydrophobic -CF2- backbone on the highly hydrophobic pristine CNFs. Ionomer adsorption behavior is gradually altered from apolar to polar group adsorption for the acid modified CNFs...

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

    International Nuclear Information System (INIS)

    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 105 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

  15. Electrospun composite nanofibers of poly vinyl pyrrolidone and zinc oxide nanoparticles modified carbon paste electrode for electrochemical detection of curcumin.

    Science.gov (United States)

    Afzali, Moslem; Mostafavi, Ali; Shamspur, Tayebeh

    2016-11-01

    A simple and novel ferrocene-nanofiber carbon paste electrode was developed to determine curcumin in a phosphate buffer solution at pH=8. ZnO nanoparticles were produced via a sonochemical process and composite nanofibers of PVP/ZnO were prepared by electrospinning. The characterization was performed by SEM, XRD and IR. The results suggest that the electrospun composite nanofibers having a large surface area promote electron transfer for the oxidation of curcumin and hence the FCNFCPE exhibits high electrocatalytic activity and performs well in regard to the oxidation of curcumin. The proposed method was successfully applied for measurement of curcumin in urine and turmeric as real samples. PMID:27524081

  16. In situ Polymerization of Multi-Walled Carbon Nanotube/Nylon-6 Nanocomposites and Their Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Baek Jong-Beom

    2008-01-01

    Full Text Available Abstract Multiwalled carbon nanotube/nylon-6 nanocomposites (MWNT/nylon-6 were prepared by in situ polymerization, whereby functionalized MWNTs (F-MWNTs and pristine MWNTs (P-MWNTs were used as reinforcing materials. The F-MWNTs were functionalized by Friedel-Crafts acylation, which introduced aromatic amine (COC6H4-NH2 groups onto the side wall. Scanning electron microscopy (SEM images obtained from the fractured surfaces of the nanocomposites showed that the F-MWNTs in the nylon-6 matrix were well dispersed as compared to those of the P-MWNTs. Both nanocomposites could be electrospun into nanofibers in which the MWNTs were embedded and oriented along the nanofiber axis, as confirmed by transmission electron microscopy. The specific strength and modulus of the MWNTs-reinforced nanofibers increased as compared to those of the neat nylon-6 nanofibers. The crystal structure of the nylon-6 in the MWNT/nylon-6 nanofibers was mostly γ-phase, although that of the MWNT/nylon-6 films, which were prepared by hot-pressing the pellets between two aluminum plates and then quenching them in icy water, was mostly α-phase, indicating that the shear force during electrospinning might favor the γ-phase, similarly to the conventional fiber spinning.

  17. Single-step synthesis of graphene-carbon nanofiber hybrid material and its synergistic magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, R.K. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India); Jeyapandiarajan, P. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee 247667 (India); Devi Chandrasekhar, K. [Cryogenics Engineering Centre, Indian Institute of Technology, Kharagpur 721302 (India); Daniel, B.S.S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee 247667 (India); Venimadhav, A. [Cryogenics Engineering Centre, Indian Institute of Technology, Kharagpur 721302 (India); Sant, S.B. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302 (India); Jacob, C., E-mail: cxj14_holiday@yahoo.com [Materials Science Centre, Indian Institute of Technology, Kharagpur 721302 (India)

    2014-12-05

    Highlights: • Graphene-CNF-alloy nanoparticle hybrid nanostructure fabricated using CVD. • The hybrid consists of highly crystalline graphene, alloy nanoparticles and CNFs. • The hybrid carbon nanomaterial exhibits interesting induced magnetism. - Abstract: Graphene-carbon nanofiber (CNF) hybrid materials were synthesized by a simple one-step chemical vapour deposition method using propane over a Co{sub 63}Ni{sub 37} alloy catalyst supported on a silicon substrate at 800 °C. The process involves catalyst de-wetting, carbon diffusion and precipitation, with the additional carbon being provided by the polymer (photo-resist, HPR-504). The formation of a graphene-CNF hybrid structure was observed in the presence of the polymer. The polymer plays a crucial role in the formation of the flat carbon nanostructures. In the absence of the polymer, only carbon nanotube growth was observed with the same catalyst under identical experimental conditions. The effect of the polymeric photo-resist layer on the growth of the hybrid structure was analyzed. Structural and morphological data in combination with the Raman spectroscopic data confirmed the formation of a few layers of highly crystalline graphene and CNFs in a hybrid structure. The magnetic behaviour of these as-grown graphene-CNF hybrid samples has been analyzed by using a superconducting quantum interference device (SQUID). The results from the magnetic measurements on these samples have also been discussed.

  18. Direct Electrochemistry of Glucose Oxidase on Novel Free-Standing Nitrogen-Doped Carbon Nanospheres@Carbon Nanofibers Composite Film

    Science.gov (United States)

    Zhang, Xueping; Liu, Dong; Li, Libo; You, Tianyan

    2015-05-01

    We have proposed a novel free-standing nitrogen-doped carbon nanospheres@carbon nanofibers (NCNSs@CNFs) composite film with high processability for the investigation of the direct electron transfer (DET) of glucose oxidase (GOx) and the DET-based glucose biosensing. The composites were simply prepared by controlled thermal treatment of electrospun polypyrrole nanospheres doped polyacrylonitrile nanofibers (PPyNSs@PAN NFs). Without any pretreatment, the as-prepared material can directly serve as a platform for GOx immobilization. The cyclic voltammetry of immobilized GOx showed a pair of well-defined redox peaks in O2-free solution, indicating the DET of GOx. With the addition of glucose, the anodic peak current increased, while the cathodic peak current decreased, which demonstrated the DET-based bioelectrocatalysis. The detection of glucose based on the DET of GOx was achieved, which displayed high sensitivity, stability and selectivity, with a low detection limit of 2 μM and wide linear range of 12-1000 μM. These results demonstrate that the as-obtained NCNSs@CNFs can serve as an ideal platform for the construction of the third-generation glucose biosensor.

  19. Morphological characterization of carbon nanofiber aerosol using tandem mobility and aerodynamic size measurements

    Energy Technology Data Exchange (ETDEWEB)

    Deye, Gregory J.; Kulkarni, Pramod, E-mail: pskulkarni@cdc.gov; Ku, Bon Ki [National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention (United States)

    2012-09-15

    Characterizing microstructural and transport properties of non-spherical particles, such as carbon nanofibers (CNF), is important for understanding their transport and deposition in human respiratory system and engineered devices such as particle filters. We describe an approach to obtain morphological information of non-spherical particles using a tandem system of differential mobility analyzer (DMA) and an electrical low-pressure impactor (ELPI). Effective density, dynamic shape factors (DSF), particle mass, and fractal dimension-like mass-scaling exponent of nanofibers were derived using the measured mobility and aerodynamic diameters, along with the known material density of CNF. Multiple charging of particles during DMA classification, which tends to bias the measured shape factors and particle mass toward higher values, was accounted for using a correction procedure. Particle mass derived from DMA-ELPI measurements agreed well with the direct mass measurements using an aerosol particle mass analyzer. Effective densities, based on mobility diameters, ranged from 0.32 to 0.67 g cm{sup -3}. The DSF of the CNF ranged from 1.8 to 2.3, indicating highly non-spherical particle morphologies.

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

    OpenAIRE

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Takeshi Hikata

    2013-04-01

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

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

    Science.gov (United States)

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

    2016-01-01

    A novel one-dimensional nanohybrid comprised of conductive graphitic carbon (GC)-coated hollow FeSe2 nanospheres decorating reduced graphene oxide (rGO) nanofiber (hollow nanosphere FeSe2@GC–rGO) was designed as an efficient anode material for sodium ion batteries and synthesized by introducing the nanoscale Kirkendall effect into the electrospinning method. The electrospun nanofibers transformed into hollow nanosphere FeSe2@GC–rGO hybrid nanofibers through a Fe@GC–rGO intermediate. The discharge capacities of the bare FeSe2 nanofibers, nanorod FeSe2–rGO–amorphous carbon (AC) hybrid nanofibers, and hollow nanosphere FeSe2@GC–rGO hyrbid nanofibers at a current density of 1 A g−1 for the 150th cycle were 63, 302, and 412 mA h g−1, respectively, and their corresponding capacity retentions measured from the 2nd cycle were 11, 73, and 82%, respectively. The hollow nanosphere FeSe2@GC–rGO hybrid nanofibers delivered a high discharge capacity of 352 mA h g−1 even at an extremely high current density of 10 A g−1. The enhanced electrochemical properties of the hollow nanosphere FeSe2@GC–rGO composite nanofibers arose from the synergetic effects of the FeSe2 hollow morphology and highly conductive rGO matrix. PMID:27033096

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

    Science.gov (United States)

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

    2016-04-01

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

  4. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO.

    Science.gov (United States)

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. PMID:27245319

  5. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO

    Science.gov (United States)

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability.With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. Electronic supplementary information

  6. Porous carbon nanofiber paper as an effective interlayer for high-performance lithium-sulfur batteries

    International Nuclear Information System (INIS)

    Lithium-sulfur (Li-S) battery with new configuration is demonstrated by inserting a flexible activated carbon nanofiber (ACNF) interlayer between the sulfur cathode and the separator. The ACNF with tunable pore structure is fabricated by a combination of electrospinning polyimide and a subsequent activation treatment. The influence of the textual characteristics of ACNFs on the electrochemical performance of Li-S batteries has been studied. The highly porous ACNF not only effectively intercepts/stabilizes the shuttling migration of polysulfides within the cathode region, but also provides reliable ionic/electronic conductivity for fast kinetics. The lightweight ACNF interlayer with higher specific surface area can yield enhanced cell performance at a low mass ratio of ACNF/sulfur (0.4). An initial specific capacity of 1224 mAh g−1 along with high Coulombic efficiency, long cycling stability and good rate capability is achieved in the modified Li-S cell

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

    Science.gov (United States)

    Kim, So Yeun; Kim, Bo-Hye

    2016-10-01

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

  8. Characterization of field emission from carbon nanofibers on a metal tip

    Science.gov (United States)

    Sakai, Y.; Tone, D.; Nagatsu, S.; Endo, T.; Kita, S.; Okuyama, F.

    2009-08-01

    Field electron emission from carbon nanofibers (CNFs) grown on a tungsten tip has been characterized by measuring emission current-voltage (I-V) curves and observing emission patterns on a phosphor screen. CNFs were vertically grown on the tip by plasma-enhanced chemical vapor deposition. Field emission from the CNFs over 100 μA was strongly dependent on emitter-anode distance, and the dominant field electrons were emitted within an angular spread of Δθ ˜25°, indicating the electron emission took place mainly from the emitter's apex area. By analyzing the I-V curves with the aid of the Fowler-Nordheim theory, the maximum current density was estimated to be about J =2×109 A/m2.

  9. A fine-focusing x-ray source using carbon-nanofiber field emitter

    Science.gov (United States)

    Sugimoto, W.; Sugita, S.; Sakai, Y.; Goto, H.; Watanabe, Y.; Ohga, Y.; Kita, S.; Ohara, T.

    2010-08-01

    A fine-focusing x-ray source has been constructed employing a field electron emitter prepared by growing carbon-nanofibers (CNFs) on a metal tip. The x-ray source is composed of a CNF field electron emitter, an electrostatic lens, two magnetic lenses, and a W-target for generating x-rays by electron impact. The CNFs provided field electrons with a current density of J ˜5×109 A/m2, which was evaluated with the aid of Fowler-Nordheim theory. The electron beam extracted from the CNF emitter was accelerated to the energies of E =10-25 keV, and then focused by the lenses. By recording the x-ray images of test charts, the optimum resolution of the x-ray source was estimated to be approximately Dx=0.5 μm.

  10. Catalytic and capacity properties of nanocomposites based on cobalt oxide and nitrogen-doped carbon nanofibers

    Institute of Scientific and Technical Information of China (English)

    Olga Yu. Podyacheva; Andrei I. Stadnichenko; Svetlana A. Yashnik; Olga A. Stonkus; Elena M. Slavinskaya; Andrei I. Boronin; Andrei V. Puzynin; Zinfer R. Ismagilov

    2014-01-01

    The nanocomposites based on cobalt oxide and nitrogen-doped carbon nanofibers (N-CNFs) with cobalt oxide contents of 10-90 wt%were examined as catalysts in the CO oxidation and superca-pacity electrodes. Depending on Со3О4 content, such nanocomposites have different morphologies of cobalt oxide nanoparticles, distributions over the bulk, and ratios of Со3+/Co2+ cations. The 90%Со3О4-N-CNFs nanocomposite showed the best activity because of the increased concentration of defects in N-CNFs. The capacitance of electrodes containing 10%Со3О4-N-CNFs was 95 F/g, which is 1.7 times higher than electrodes made from N-CNFs.

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

    Directory of Open Access Journals (Sweden)

    Youliang Shen

    2014-01-01

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

  12. 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.

  13. Mechanical Properties of Carbon Nanofiber Reinforced Polymer Composites-Molecular Dynamics Approach

    Science.gov (United States)

    Sharma, Sumit; Chandra, Rakesh; Kumar, Pramod; Kumar, Navin

    2016-06-01

    Molecular dynamics simulation has been used to study the effect of carbon nanofiber (CNF) volume fraction ( V f) and aspect ratio ( l/d) on mechanical properties of CNF-reinforced polypropylene (PP) composites. Materials Studio 5.5 has been used as a tool for finding the modulus and damping in composites. CNF composition in PP was varied by volume from 0% to 16%. The aspect ratio of CNF was varied from l/d = 5 to l/d = 100. Results show that, with only 2% addition by volume of CNF in PP, E 11 increases 748%. Increase in E 22 is much less in comparison to the increase in E 11. With the increase in the CNF aspect ratio ( l/d) up to l/d = 60, the longitudinal loss factor ( η 11) decreases rapidly. The results of this study have been compared with those available in the literature.

  14. Fabrication and properties of ethylene vinyl acetate-carbon nanofiber nanocomposites.

    Science.gov (United States)

    George, Jinujacob; Bhowmick, Anil K

    2008-01-01

    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. PMID:20596388

  15. Sensing nitric oxide with a carbon nanofiber paste electrode modified with a CTAB and nafion composite

    International Nuclear Information System (INIS)

    We describe an electrochemical sensor for nitric oxide that was obtained by modifying the surface of a nanofiber carbon paste microelectrode with a film composed of hexadecyl trimethylammonium bromide and nafion. The modified microelectrode displays excellent catalytic activity in the electrochemical oxidation of nitric oxide. The mechanism was studied by scanning electron microscopy and cyclic voltammetry. Under optimal conditions, the oxidation peak current at a working voltage of 0.75 V (vs. SCE) is related to the concentration of nitric oxide in the 2 nM to 0.2 mM range, and the detection limit is as low as 2 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitric oxide released from mouse hepatocytes. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  17. 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.

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

    International Nuclear Information System (INIS)

    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. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-15

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2012-07-24

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

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

    Science.gov (United States)

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

    2016-06-15

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

  4. 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.

  5. Self aligned hysteresis free carbon nanotube field-effect transistors

    Science.gov (United States)

    Shlafman, M.; Tabachnik, T.; Shtempluk, O.; Razin, A.; Kochetkov, V.; Yaish, Y. E.

    2016-04-01

    Hysteresis phenomenon in the transfer characteristics of carbon nanotube field effect transistor (CNT FET) is being considered as the main obstacle for successful realization of electronic devices based on CNTs. In this study, we prepare four kinds of CNTFETs and explore their hysteretic behavior. Two kinds of devices comprise on-surface CNTs (type I) and suspended CNTs (type II) with thin insulating layer underneath and a single global gate which modulates the CNT conductance. The third and fourth types (types III and IV) consist of suspended CNT over a metallic local gate underneath, where for type IV the local gate was patterned self aligned with the source and drain electrodes. The first two types of devices, i.e., type I and II, exhibit substantial hysteresis which increases with scanning range and sweeping time. Under high vacuum conditions and moderate electric fields ( |E |>4 ×106 V /cm ), the hysteresis for on-surface devices cannot be eliminated, as opposed to suspended devices. Interestingly, type IV devices exhibit no hysteresis at all at ambient conditions, and from the different roles which the global and local gates play for the four types of devices, we could learn about the hysteresis mechanism of this system. We believe that these self aligned hysteresis free FETs will enable the realization of different electronic devices and sensors based on CNTs.

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

    Science.gov (United States)

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

    2016-08-01

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

  7. 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.

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

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

    2006-05-01

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

  10. Nitrogen-doped porous carbon nanofiber webs/sulfur composites as cathode materials for lithium-sulfur batteries

    International Nuclear Information System (INIS)

    Nitrogen-doped porous carbon nanofiber webs-sulfur composites (N-CNFWs/S) were synthesized for the first time with sulfur (S) encapsulated into nitrogen-doped porous carbon nanofiber webs (N-CNFWs) via a modified oxidative template route, carbonization-activation and thermal treatment. The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), X-ray powder diffraction (XRD), and thermogravimetry (TG) measurements. The results show that sulfur is well dispersed and immobilized homogeneously in the micropores of nitrogen-doped porous carbon nanofiber webs (N-CNFWs) with high electrical conductivity, surface area and large pore volume. The electrochemical tests show that the N-CNFWs/S composites with 60 wt. % of S have a high initial discharge capacity of 1564 mA h g−1, a good cycling stability at the current density of 175 mA g−1, and excellent rate capability (reversible discharging capacity of above 400 mA h g−1 at 1600 mA g−1)

  11. 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.

  12. Electrospun carbon nanofibers from polyacrylonitrile blended with activated or graphitized carbonaceous materials for improving anodic bioelectrocatalysis.

    Science.gov (United States)

    Patil, Sunil A; Chigome, Samuel; Hägerhäll, Cecilia; Torto, Nelson; Gorton, Lo

    2013-03-01

    The electrospun carbon nanofibers obtained from polyacrylonitrile (PAN) and PAN blends with either activated carbon (PAN-AC) or graphite (PAN-GR) were tested as anodes using Shewanella oneidensis MR-1. Extensive physico-chemical and electrochemical characterization confirmed their formation, their fibrous and porous nature, and their suitability as electrodes. N2 adsorption measurements revealed high specific surface area (229.8, 415.8 and 485.2m(2) g(-1)) and porosity (0.142, 0.202 and 0.239cm(3)g(-1)) for PAN, PAN-AC and PAN-GR, respectively. The chronoamperometric measurements showed a considerable decrease in start-up time and more than a 10-fold increase in the generation of current with these electrodes (115, 139 and 155μAcm(-2) for PAN, PAN-AC and PAN-GR, respectively) compared to the graphite electrode (11.5μAcm(-2)). These results indicate that the bioelectrocatalysis benefits from the blending of PAN with activated or graphitized carbonaceous materials, presumably due to the increased specific surface area, total pore volume and modification of the carbon microstructure. PMID:23399497

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

    Science.gov (United States)

    Ashfaq, Mohammad; Verma, Nishith; Khan, Suphiya

    2016-02-01

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

  14. Carbon Nanofiber/3D Nanoporous Silicon Hybrids as High Capacity Lithium Storage Materials.

    Science.gov (United States)

    Park, Hyeong-Il; Sohn, Myungbeom; Kim, Dae Sik; Park, Cheolho; Choi, Jeong-Hee; Kim, Hansu

    2016-04-21

    Carbon nanofiber (CNF)/3D nanoporous (3DNP) Si hybrid materials were prepared by chemical etching of melt-spun Si/Al-Cu-Fe alloy nanocomposites, followed by carbonization using a pitch. CNFs were successfully grown on the surface of 3DNP Si particles using residual Fe impurities after acidic etching, which acted as a catalyst for the growth of CNFs. The resulting CNF/3DNP Si hybrid materials showed an enhanced cycle performance up to 100 cycles compared to that of the pristine Si/Al-Cu-Fe alloy nanocomposite as well as that of bare 3DNP Si particles. These results indicate that CNFs and the carbon coating layer have a beneficial effect on the capacity retention characteristics of 3DNP Si particles by providing continuous electron-conduction pathways in the electrode during cycling. The approach presented here provides another way to improve the electrochemical performances of porous Si-based high capacity anode materials for lithium-ion batteries. PMID:26970098

  15. 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.

  16. High-performance aqueous asymmetric supercapacitor based on carbon nanofibers network and tungsten trioxide nanorod bundles electrodes

    International Nuclear Information System (INIS)

    The demand for high-performance energy storage devices such as supercapacitors and lithium-ion batteries has been increasing to meet the application requirements of renewable energy systems. Here, high energy density aqueous asymmetric supercapacitor (ASC) is assembled based on carbon nanofibers (CNF) network positive electrode and tungsten trioxide (WO3) nanorod bundles negative electrode. Polyaniline-based CNF are prepared by direct carbonization of polyaniline nanofibers. WO3 nanorod bundles are synthesized via a simple sodium chloride assisted hydrothermal process. The CNF//WO3 ASC device operates with a voltage of 1.6 V and achieved a high energy density of 35.3 Wh kg−1 at a power density of 314 W kg−1. Furthermore, the device shows an excellent cycling performance with capacitance retention of 88% after 1000 cycles

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  18. Consolidation of carbon nanofiber/copper composites by hot-pressing and spark plasma sintering: a comparative study.

    Science.gov (United States)

    Barcena, Jorge; Martinez, Vladimir; Martinez, Ramon; Maudes, Jon; Sarries, Jose-Ignacio; Carol, Iñaki; Gonzalez, Javier-Jesus; Coleto, Javier

    2009-03-01

    Vapour grown carbon nanofibers have been incorporated into a copper matrix at 20 and 40 volume fractions. The manufacturing route involves the dispersion of the carbon nanofibers and their subsequent coating by electroless plating with copper. The consolidation of the composite powders was performed by two different techniques: hot-pressing and spark plasma sintering. A comparative study of the two processes is reported, in terms of microstructure, dispersion and porosity. The consolidation by hot-pressing (at 900 degrees C, 30 MPa) led to poreless composites (relative density > 96%) and to a homogeneous microstructure. On the other hand, spark plasma sintering (at 400 degrees C, 75 MPa) led to lower densification (relative density < 96%) and heterogeneous microstructure. PMID:19435042

  19. 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.

  20. Third Harmonic Generation from Aligned Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Morris, Darius T., Jr.

    Optical properties of single-wall carbon nanotubes (SWCNTs) have been extensively studied during the last decade, and much basic knowledge has been accumulated on how light emission, scattering, and absorption occur in the realm of linear optics. However, their nonlinear optical properties remain largely unexplored. Here, we have observed strong third harmonic generation from highly aligned SWCNTs with intense mid-infrared radiation. Through power dependent experiments, we have determined the absolute value of the third-order nonlinear optical susceptibility, chi(3), of our SWCNT film to be 6.92 x 10--12 esu, which is three orders of magnitude larger than that of the fused silica reference sample we used. Furthermore, through polarization-dependent third harmonic generation experiments, all the nonzero tensor elements of chi(3) have also been extracted. The contribution of the weaker tensor elements to the overall chi (3) signal has been calculated to be approximately 1/6 of that of the dominant c3z zzz component. These results open up new possibilities for application of carbon nanotubes in optoelectronics.

  1. 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. PMID:21780388

  2. 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.

  3. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S., E-mail: msarnold@wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, Wisconsin 53706 (United States)

    2014-02-24

    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{sup −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{sup 7} and 46 cm{sup 2} V{sup −1} s{sup −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{sup −1} and the on/off ratio is 4 × 10{sup 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.

  5. 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.

  6. Functional properties of electrospun NiO/RuO{sub 2} composite carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yongzhi [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576 (Singapore); Physics Department, National University of Singapore, Singapore 117542 (Singapore); NUS Graduate School for Integrated Science and Engineering, 10 Kent Ridge Crescent, National University of Singapore, Singapore 119260 (Singapore); Balakrishna, Rajiv [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576 (Singapore); Physics Department, National University of Singapore, Singapore 117542 (Singapore); Reddy, M.V., E-mail: phymvv@nus.edu.sg [Physics Department, National University of Singapore, Singapore 117542 (Singapore); Nair, A. Sreekumaran, E-mail: nniansn@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576 (Singapore); Chowdari, B.V.R. [Physics Department, National University of Singapore, Singapore 117542 (Singapore); Ramakrishna, S. [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576 (Singapore); Kind Saud University, Riyadh 11451 (Saudi Arabia)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Fabrication of carbon nanofibers with nickel-ruthenium composites by electrospinning. Black-Right-Pointing-Pointer An interesting observation of increase in capacitance with increase in the number of cycles for supercapacitor applications. Black-Right-Pointing-Pointer Li ion battery testing showed a stable capacity ranging from 350 mAh g{sup -1} to 400 mAh g{sup -1}. Black-Right-Pointing-Pointer Lower impedance with the incorporation of 15 wt% Ru precursor than those without Ru. - Abstract: One-dimensional (1D) nickel oxide/ruthenium oxide (NiO/RuO{sub 2})-carbon composite nanofibers (NiRu-C-NFs) were fabricated via electrospinning of a homogenous mixture of polyacrylonitrile (PAN) and Ni/Ru salt precursors at different ratios followed by heat treatments. The 1D nanostructures of the composite material were characterized by field-emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), Rietveld refinement and Brunauer-Emmett-Teller (BET) surface area measurements. Li-cycling properties were evaluated using cyclic voltammetry and galvanostatic properties. The asymmetric hybrid supercapacitor studies were carried out with activated carbon as a cathode and NiRu-C-NFs composites as anodes in the cycling range, 0.005-3.0 V using 1 M LiPF{sub 6} (EC;DMC) electrolyte. NiRu-C-NFs fabricated from 5 wt% nickel (II) and 15 wt% ruthenium (III) precursors showed a capacitance up to {approx}60 F g{sup -1} after 30 cycles. Anodic Li-cycling studies of NiRu-C-NF-0 and NiRu-C-NF-2 composite samples showed a reversible capacity of 230 and 350 m Ahg{sup -1} at current rate of 72 mA g{sup -1} at the end of 40th cycle in the voltage range of 0.005-3.0 V. Electrochemical impedance studies (EIS) on NiRu-C-NFs showed lower impedance value for 15 wt% Ru than the bare sample.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeonyoon; Stein, Itai Y. [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Devoe, Mackenzie E. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Lewis, Diana J.; Lachman, Noa; Buschhorn, Samuel T.; Wardle, Brian L., E-mail: wardle@mit.edu [Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Kessler, Seth S. [Metis Design Corporation, 205 Portland St., Boston, Massachusetts 02114 (United States)

    2015-02-02

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

  12. 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.

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

    Science.gov (United States)

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

    2016-01-20

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

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

    Science.gov (United States)

    Evora, M. C.; Araujo, J. R.; Ferreira, E. H. M.; Strohmeier, B. R.; Silva, L. G. A.; Achete, C. A.

    2015-04-01

    Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO4·7H2O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

  15. NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications

    Directory of Open Access Journals (Sweden)

    Dawei Li

    2015-11-01

    Full Text Available NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties of the biosensor. The finally prepared biosensor showed favorable electrocatalytic effects toward hydroquinone. The detection limit was 90 nM (S/N = 3, the sensitivity was 1.5 µA µM−1, the detection linear range was 4 × 10−7–2.37 × 10−6 M. In addition, this biosensor exhibited satisfactory repeatability, reproducibility, anti-interference properties and stability. Besides, the sensor achieved the detection of hydroquinone in lake water.

  16. Effect of filler surface properties on stress relaxation behavior of carbon nanofiber/polyurethane nanocomposites

    Science.gov (United States)

    Sedat Gunes, I.; Jimenez, Guillermo; Jana, Sadhan

    2009-03-01

    The effect of carbon nanofiber (CNF) surface properties on tensile stress relaxation behavior of CNF/polyurethane (PU) nanocomposites was analyzed. PU was synthesized from methylene diisocyanate, polypropylene glycol (PPG diol), and butanediol. CNF, oxidized CNF (ox-CNF), and PPG diol grafted CNF (ol-CNF) were selected as fillers. ol-CNF was obtained by grafting PPG diol onto ox-CNF by reacting it with the carboxyl groups present on ox-CNF surface. The atomic ratios of oxygen to carbon present on the filler surfaces were 0.13 and 0.18 on ox-CNF and on ol-CNF as compared to 0.015 on CNF, mostly due to the presence oxygen containing polar groups on the surfaces of the former. The composites were prepared by in-situ polymerization and melt mixing in a chaotic mixer. The stress relaxation behavior of composites was determined at room temperature after inducing a tensile strain of 100%. The presence of fillers augmented the rate of stress relaxation in composites which was highest in the presence of CNF. The results suggested that relatively weak polymer-filler interactions in composites of CNF promoted higher stress relaxation.

  17. Textural and electrochemical characterization of porous carbon nanofibers as electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao-Wei; Wu, Yung-Tai; Hu, Chi-Chang; Li, Yuan-Yao [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China)

    2007-10-11

    Porous carbon nanofibers (CNFs) enriched with the graphitic structure were synthesized by thermal decomposition from a mixture containing polyethylene glycol and nickel chloride (catalyst). The textural and electrochemical properties of porous CNFs were systematically compared with those of commercially available multi-walled carbon nanotubes (MWCNTs). The high ratio of mesopores and large amount of open edges of porous CNFs with a higher specific surface area, very different from that of MWCNTs, are favorable for the penetration of electrolytes meanwhile the graphene layers of porous CNFs serve as a good electronic conductive medium of electrons. The electrochemical properties of porous CNFs and MWCNTs were characterized for the application of supercapacitors using cyclic voltammetry, galvanostatic charge-discharge method, and electrochemical impedance spectroscopic analyses. The porous CNFs show better capacitive performances (C{sub S} = 98.4 F g{sup -1} at 25 mV s{sup -1} and an onset frequency of behaving as a capacitor at 1.31 kHz) than that of MWCNTs (C{sub S} = 17.8 F g{sup -1} and an onset frequency at 1.01 kHz). This work demonstrates the promising capacitive properties of porous CNFs for the application of electrochemical supercapacitors. (author)

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

    CERN Document Server

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

    2013-01-01

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

  19. Electrospun carbon nanofibers/electrocatalyst hybrids as asymmetric electrodes for vanadium redox flow battery

    Science.gov (United States)

    Wei, Guanjie; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei

    2015-05-01

    To improve the electrochemical activity of polyacrylonitrile (PAN)-based electrospun carbon nanofibers (ECNFs) toward vanadium redox couples, the multi-wall carbon nanotubes (CNTs) and Bi-based compound as electrocatalyst have been embedded in the ECNFs to make composite electrode, respectively. The morphology and electrochemical properties of pristine ECNFs, CNTs/ECNFs and Bi/ECNFs have been characterized. Among the three kinds of electrodes, the CNTs/ECNFs show best electrochemical activity toward VO2+/VO2+ redox couple, while the Bi/ECNFs present the best electrochemical activity toward V2+/V3+ redox couple. Furthermore, the high overpotential of hydrogen evolution on Bi/ECNFs makes the side-reaction suppressed. Because of the large property difference between the two composite electrodes, the CNTs/ECNFs and Bi/ECNFs are designed to act as positive and negative electrode for vanadium redox flow battery (VRFB), respectively. It not only does improve the kinetics of two electrode reactions at the same time, but also reduce the kinetics difference between them. Due to the application of asymmetric electrodes, performance of the cell is improved greatly.

  20. 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.

  1. 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.

  2. Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

    Science.gov (United States)

    Park, Cheol; Wiklinson, John; Banda, Sumanth; Ounaies, Zoubeida; Wise, Kristopher E.; Sauti, Godfrey; Lillehei, Peter T.; Harrison, Joycelyn S.

    2005-01-01

    While high shear alignment has been shown to improve the mechanical properties of single wall carbon nanotubes (SWNT)-polymer composites, it is difficult to control and often results in degradation of the electrical and dielectric properties of the composite. Here, we report a novel method to actively align SWNTs in a polymer matrix, which allows for control over the degree of alignment of SWNTs without the side effects of shear alignment. In this process, SWNTs are aligned via field-induced dipolar interactions among the nanotubes under an AC electric field in a liquid matrix followed by immobilization by photopolymerization while maintaining the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy and the morphology of the aligned nanocomposites was investigated by high resolution scanning electron microscopy. The structure of the field induced aligned SWNTs is intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties in addition to improving the mechanical properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field conditions.

  3. Visible Aligned Carbon Nanotube-MoS2 Hybrids

    Science.gov (United States)

    Wang, Rui; Hong, Tu; Wang, Tianjiao; Ali, Ahmad Iffat; Chani, Devpaul Singh; Xu, Yaqiong

    Single-walled carbon nanotubes (SWNTs) have gained great interest due to their excellent electrical, mechanical and thermal properties. Recent progress in two-dimensional (2D) materials has opened up new horizons in the realm of physics and engineering that could lead to the revolution of future electronics and optoelectronics. Various hybrid structures have been developed for different applications. Here we report a facile method to synthesize ultrathin 2D hybrids between horizontally-aligned SWNT and monolayer molybdenum sulfide (MoS2) through chemical vapor deposition (CVD). These hybrid structures can be imaged under an optical microscope; and their Raman mapping indicates that MoS2 flakes are partially grown on top of SWNTs. Moreover, strong photocurrent signals have been observed in SWNT-MoS2 hybrids through scanning photocurrent measurements. These fundamental studies may provide a new way to fabricate 2D hybrids for future electronics and optoelectronics. Department of Electrical Engineering & Computer Science, Vanderbilt University, Nashville, TN 37235, USA.

  4. Nanoscratch technique for aligning multiwalled carbon nanotubes synthesized by the arc discharge method in open air

    Indian Academy of Sciences (India)

    A Joseph Berkmans; M Jagannatham; Prathap Haridoss

    2015-08-01

    Horizontally aligned and densely packed multiwalled carbon nanotubes (MWCNTs) were synthesized in an open air, without the need for a controlled atmosphere, using a rotating cathode arc discharge method with the help of a metal scraper. The physical force exerted by the scraper results in in-situ alignment of MWCNTs along the direction of scrape marks. This strategy, which enables the alignment of nanotubes in a controlled fashion to any length and direction of interest, was examined to determine the force required to align a nanotube. A model is developed to understand the alignment process. Using the nanoscratch technique to mimic this strategy, and incorporating the data obtained from the nanoscratch technique into the model developed, the minimum force required to align a MWCNT, as well as the energy required to align a gram of nanotubes, has been estimated. The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs.

  5. Preparation of carbon nanoparticles and nanofibers by a simple microwave based method and studying the field emission properties

    International Nuclear Information System (INIS)

    Research highlights: → A novel and simple microwave based method for preparation of carbon nanostructures were developed. → The mw-plasma method can produce catalyst nanoparticles from a solid metallic source. → The resulting nanostructure exhibit good field emission (FE) properties. → Deposition of nanoparticles through the mw-plasma method improves field emission properties. - Abstract: A novel, simple and fast method for preparation of graphitic nanostructures such as nanofibers and nanospheres which uses a standard microwave oven is described. In this method polystyrene is used as carbon source and a solid metal such as nickel or iron provides both the trigger to initiate the plasma, as well as a source for sputtering catalyst particles which are required for formation of nanofibers. The mechanism of this process is discussed through analysis of different properties of the resulting products, by examining the effect of changing the microwave processing time and the nature of the metallic trigger/catalyst source. The effect of morphology of nanoparticles (nanofibers vs. nanospheres), as well as the effect of trigger/catalyst material and the deposition method on electron field emission properties of these samples, are also investigated.

  6. An inner filter effect based sensor of tetracycline hydrochloride as developed by loading photoluminescent carbon nanodots in the electrospun nanofibers.

    Science.gov (United States)

    Lin, Min; Zou, Hong Yan; Yang, Tong; Liu, Ze Xi; Liu, Hui; Huang, Cheng Zhi

    2016-02-01

    The inner filter effect (IFE), which results from the absorption of the excitation or emission light by absorbers, has been employed as an alternative approach in sensing systems due to its flexibility and simplicity. In this work, highly photoluminescent carbon nanodots (CDs), which were simply prepared through a new one-step microwave synthesis route, were loaded in electrospun nanofibers, and the obtained nanofibers were then successfully applied to develop a fluorescent IFE-based visual sensor for tetracycline hydrochloride (Tc) sensing in milk. This developed visual sensor has high selectivity owing to the requirements of the spectral overlap between the CDs and Tc, showing high promise in sensing chemistry with an efficient response and economic effect. PMID:26781447

  7. Highly active and stable platinum catalyst supported on porous carbon nanofibers for improved performance of PEMFC

    International Nuclear Information System (INIS)

    Porous carbon nanofibers (PCNFs) were used as the support to prepare platinum (Pt) catalyst (Pt/PCNFs) for proton exchange membrane fuel cell (PEMFC) applications. As a comparison, Pt supported on carbon black (Vulcan XC-72) (Pt/Vulcan) was also synthesized by the same ethylene glycol reduction method. Platinum was more uniformly deposited on PCNFs than that on the Vulcan XC-72. The electrocatalytic activity and stability of the resultant catalysts along with the commercial one (JM20) were investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) with a rotating disk electrode (RDE). The Pt/PCNFs exhibited much-enhanced electrocatalytic activity and stability compared with the Pt/Vulcan and JM20. The mass activity (at 0.80 V) of Pt/PCNFs is 2.6 times higher and 20% higher than that of Pt/Vulcan and JM20, respectively; the Pt/PCNFs retained about 50% of ECSA whereas JM20 and Pt/Vulcan kept only 25% and 5% of ECSA, respectively, even after 1000 cycles. Furthermore, the single cell performance of Pt/PCNFs was superior to that of Pt/Vulcan and even better than JM20 during high current densities. The cross-section of the membrane electrode assembly (MEA) showed that the Pt/PCNFs construct a loose three-dimensionally connected catalyst layer that is totally different from the tightly stacking catalyst layer composed of carbon black support. Thus, the mass transfer resistance is reduced and water drainage becomes easy when Pt/PCNFs were used as cathode catalyst. These results indicate PCNFs a promising candidate as catalyst supports for the enhancement of PEMFC performance

  8. An inner filter effect based sensor of tetracycline hydrochloride as developed by loading photoluminescent carbon nanodots in the electrospun nanofibers

    Science.gov (United States)

    Lin, Min; Zou, Hong Yan; Yang, Tong; Liu, Ze Xi; Liu, Hui; Huang, Cheng Zhi

    2016-01-01

    The inner filter effect (IFE), which results from the absorption of the excitation or emission light by absorbers, has been employed as an alternative approach in sensing systems due to its flexibility and simplicity. In this work, highly photoluminescent carbon nanodots (CDs), which were simply prepared through a new one-step microwave synthesis route, were loaded in electrospun nanofibers, and the obtained nanofibers were then successfully applied to develop a fluorescent IFE-based visual sensor for tetracycline hydrochloride (Tc) sensing in milk. This developed visual sensor has high selectivity owing to the requirements of the spectral overlap between the CDs and Tc, showing high promise in sensing chemistry with an efficient response and economic effect.The inner filter effect (IFE), which results from the absorption of the excitation or emission light by absorbers, has been employed as an alternative approach in sensing systems due to its flexibility and simplicity. In this work, highly photoluminescent carbon nanodots (CDs), which were simply prepared through a new one-step microwave synthesis route, were loaded in electrospun nanofibers, and the obtained nanofibers were then successfully applied to develop a fluorescent IFE-based visual sensor for tetracycline hydrochloride (Tc) sensing in milk. This developed visual sensor has high selectivity owing to the requirements of the spectral overlap between the CDs and Tc, showing high promise in sensing chemistry with an efficient response and economic effect. Electronic supplementary information (ESI) available: Experimental section and additional figures (Fig. S1-S9). See DOI: 10.1039/c5nr08177g

  9. Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol-based nanocomposite material for lithium-ion electrolyte battery separator.

    Science.gov (United States)

    Sharma, Ajit K; Khare, Prateek; Singh, Jayant K; Verma, Nishith

    2013-04-01

    A novel nanocomposite polyvinyl alcohol precursor-based material dispersed with the web of carbon microfibers and carbon nanofibers is developed as lithium (Li)-ion electrolyte battery separator. The primary synthesis steps of the separator material consist of esterification of polyvinyl acetate to produce polyvinyl alcohol gel, ball-milling of the surfactant dispersed carbon micro-nanofibers, mixing of the milled micron size (~500 nm) fibers to the reactant mixture at the incipience of the polyvinyl alcohol gel formation, and the mixing of hydrophobic reagents along with polyethylene glycol as a plasticizer, to produce a thin film of ~25 μm. The produced film, uniformly dispersed with carbon micro-nanofibers, has dramatically improved performance as a battery separator, with the ion conductivity of the electrolytes (LiPF6) saturated film measured as 0.119 S-cm(-1), approximately two orders of magnitude higher than that of polyvinyl alcohol. The other primary characteristics of the produced film, such as tensile strength, contact angle, and thermal stability, are also found to be superior to the materials made of other precursors, including polypropylene and polyethylene, discussed in the literature. The method of producing the films in this study is novel, simple, environmentally benign, and economically viable.

  10. Synthesis and Application of Si/Carbon Nanofiber Composites Based on Ni and Mo Catalysts for Anode Material of Lithium Secondary Batteries.

    Science.gov (United States)

    Jang, Eunyi; Park, Heal-Ku; Lee, Chang-Seop

    2016-05-01

    In this paper, carbon nanofibers (CNFs) and Si/carbon nanofiber composites were synthesized for use as the anode material of lithium secondary batteries. Catalysts were prepared based on Ni and Mo metals and CNFs were grown through chemical vapor deposition (CVD). In addition, the grown CNFs were mixed with silicon particles to synthesize Si/carbon nanofibers composites. The physiochemical characteristics of the synthesized CNFs and Si/carbon nanofiber composites were analyzed by SEM, EDS, XRD, Raman, BET and XPS. The electrochemical characteristics were investigated by using cyclic voltammetry and galvanostatic charge-discharge. Using CNFs and Si/carbon nanofiber composites as the anode material, three electrode cells were assembled and the electrochemical characteristics were measured using LiPF6 and LiClO4 as electrolytes. As a result of the galvanostatic charge-discharge of CNFs that were grown through catalysts with Ni and Mo concentration ratio of 6:4, the initial discharge capacity when using LiPF6 as the electrolyte was 570 mAh/g and the retention rate was 15.05%. In the case of using LiClO4 as the electrolyte, the initial discharge capacity was 263 mAh/g and the retention rate was 67.23%. PMID:27483824

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

    Science.gov (United States)

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

    2016-12-01

    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 (Ip) 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. PMID:27612735

  12. Highly sensitive hydrogen peroxide sensor based on a glassy carbon electrode modified with platinum nanoparticles on carbon nanofiber heterostructures

    International Nuclear Information System (INIS)

    We are presenting a sensor for hydrogen peroxide (H2O2) that is based on the use of a heterostructure composed of Pt nanoparticles (NPs) and carbon nanofibers (CNFs). High-density Pt NPs were homogeneously loaded onto a three-dimensional nanostructured CNF matrix and then deposited in a glassy carbon electrode (GCE). The resulting sensor synergizes the advantages of the conducting CNFs and the nanoparticle catalyst. The porous structure of the CNFs also favor the high-density immobilization of the NPs and the diffusion of water-soluble molecules, and thus assists the rapid catalytic oxidation of H2O2. If operated at a working voltage of −0.2 V (vs. Ag/AgCl), the modified GCE exhibits a linear response to H2O2 in the 5 μM to 15 mM concentration range (total analytical range: 5 μM to 100 mM), with a detection limit of 1.7 μM (at a signal-to-noise ratio of 3). The modified GCE is not interfered by species such as uric acid and glucose. Its good stability, high selectivity and good reproducibility make this electrode a valuable tool for inexpensive amperometric sensing of H2O2. (author)

  13. Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

    Science.gov (United States)

    Li, Xiaona; Chen, Shuo; Fan, Xinfei; Quan, Xie; Tan, Feng; Zhang, Yaobin; Gao, Jinsuo

    2015-06-01

    Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions.

  14. Post-treatment method for improving field emission from carbon nanotubes/nanofibers

    Institute of Scientific and Technical Information of China (English)

    GUO Ping-sheng; SUN Zhuo; ZHENG Zhi-hao

    2006-01-01

    A novel post-treatment method is reported for improving the field emission characteristics of screen-printed carbon nanotubes/nanofibers (CNTs/CNFs) cathodes.After the treatment at the temperature of 500℃ in H2 and C2H2 gas for 20 minutes,the CNTs/CNFs cathodes exhibit much better field emission properties than those untreated.The emission current increases from 0.02 mA/cm2 to 0.5 mA/cm2 at 3.9 V/μm with a decrease in the turn-on field from 2.4 V to 1.8 V ,and the emission site density is increased by almost four orders in magnitude.The enhanced field emission of treated CNTs/CNFs cathodes is attributed to the appearance of a large number of exposed CNTs/CNFs caused by heat treatment.This surface morphology is very favorable for the electron field emission.

  15. Physicochemical and electrochemical properties of carbon nanotube/graphite nanofiber hybrid nanocomposites for supercapacitor

    Science.gov (United States)

    Ramli, Nurul Infaza Talalah; Abdul Rashid, Suraya; Sulaiman, Yusran; Mamat, Md Shuhazlly; Mohd Zobir, Syazwan Afif; Krishnan, Shutesh

    2016-10-01

    This work reports the combination of graphitic nanofibers (GNF) and carbon nanotubes (CNT) as the electrode material for supercapacitors. The hybrid CNT/GNF was prepared via a synthesis route that involved simple sonication and stirring. The loading of CNT was varied from 5 to 40% weight percentages. A specific capacitance of 174 Fg-1 has been obtained for 20 wt% CNT loading at 50 mV F g-1th 1 M H2SO4 aqueous solution as the electrolyte. The addition of 20 wt% CNT raised the specific capacitance by 87% more than the GNF electrodes. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscope (TEM) reveals the random entanglement of CNT and GNF that create diffusion paths for ion transportation. Conformational changes were monitored by Raman spectroscopy, where two dominant peaks (D and G) showed strong intensities and sharp profiles. X-ray Diffraction spectroscopy (XRD) confirmed the purity of CNT/GNF hybrid nanocomposites. 20 wt% of CNT addition also shows an outstanding thermal stability. The marked improvement of the hybrid performance was attributed to the high conductivity of the two constituent materials, coupled with sufficient accessible active sites for electrochemical reactions that resulted in a synergistic behavior of the materials.

  16. Free-standing porous carbon nanofiber/ultrathin graphite hybrid for flexible solid-state supercapacitors.

    Science.gov (United States)

    Qin, Kaiqiang; Kang, Jianli; Li, Jiajun; Shi, Chunsheng; Li, Yuxiang; Qiao, Zhijun; Zhao, Naiqin

    2015-01-27

    A micrometer-thin solid-state supercapacitor (SC) was assembled using two pieces of porous carbon nanofibers/ultrathin graphite (pCNFs/G) hybrid films, which were one-step synthesized by chemical vapor deposition using copper foil supported Co catalyst. The continuously ultrathin graphite sheet (∼ 25 nm) is mechanically compliant to support the pCNFs even after etching the copper foil and thus can work as both current collector and support directly with nearly ignorable fraction in a SC stack. The pCNFs are seamlessly grown on the graphite sheet with an ohmic contact between the pCNFs and the graphite sheet. Thus, the accumulated electrons/ions can duly transport from the pCNFs to graphite (current collector), which results in a high rate performance. The maximum energy density and power density based on the whole device are up to 2.4 mWh cm(-3) and 23 W cm(-3), which are even orders higher than those of the most reported electric double-layer capacitors and pseudocapacitors. Moreover, the specific capacitance of the device has 96% retention after 5000 cycles and is nearly constant at various curvatures, suggesting its wide application potential in powering wearable/miniaturized electronics. PMID:25567451

  17. Electrophoretic nanotechnology of graphene-carbon nanotube and graphene-polypyrrole nanofiber composites for electrochemical supercapacitors.

    Science.gov (United States)

    Shi, Kaiyuan; Zhitomirsky, Igor

    2013-10-01

    Thin films of multiwalled carbon nanotubes (MWCNT), graphene and polypyrrole (PPy) nanofibers were prepared by cathodic electrophoretic deposition (EPD) from aqueous suspensions, containing safranin (SAF) as a new dispersant. The results of Fourier transform infrared spectroscopy, UV-Vis spectroscopy studies and sedimentation tests, coupled with deposition yield and electron microscopy data showed that SAF adsorbed on MWCNT, graphene and PPy, provided their dispersion and charging in the suspensions and allowed efficient EPD. The deposition yield can be controlled by the variation of SAF concentration in the suspensions and deposition time. The use of SAF as a co-dispersant for MWCNT, graphene and PPy, allowed controlled EPD of composite graphene-MWCNT and graphene-PPy films. The proposed approach for the deposition of PPy paves the way for EPD of neutral polymers using organic dyes as dispersing and charging agents. The composite films were investigated for application in electrochemical supercapacitors (ES). The graphene-MWCNT and graphene-PPy films showed significant increase in capacitance, decrease in resistance and increase in capacitance retention at high charge-discharge rates compared to the films of individual components. The analysis of electrochemical testing results and electron microscopy data provided an insight into the influence of composite microstructure on electrochemical performance. The composites, prepared by EPD are promising materials for electrodes of ES. PMID:23880521

  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. A three-dimensionally chitin nanofiber/carbon nanotube hydrogel network for foldable conductive paper.

    Science.gov (United States)

    Chen, Chuchu; Yang, Chuang; Li, Suiyi; Li, Dagang

    2015-12-10

    We reported a highly conductive nanocomposite made with multiwalled carbon nanotubes (MWCNTs) and chitin nanofibers (ChNFs). The MWCNTs were dispersed into ChNFs by the simple process of vacuum-filtration, forming a three-dimensional network structure. In this approach, MWCNT acted as a filler to introduce electron channel paths throughout the ChNF skeleton. And then, a hybrid hydrogel system (20 wt.% NaOH, -18 °C) was applied to prepare the ChNF/MWCNT gel-film followed with drying process. It is found that the resultant ChNF/MWCNT gel-film exposed much more MWCNT areas forming denser structure due to the shrinking of ChNFs after the gelation treatment. Compared with ChNF/MWCNT film, the one treated under hydrogel system (ChNF/MWCNT gel-film) exhibited almost twice higher conductivity (9.3S/cm for 50 wt.% MWCNTs in gel-film; whereas 4.7S/cm for 50 wt.% MWCNTs in film). Moreover, the facile and low-cost of this conductive paper may have great potential in development of foldable electronic devices.

  1. Bending actuation in a single-layer carbon-nanofiber/polypyrrole composite film and its fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai; Kim, Cheol [Kyungpook National University, Daegu (Korea, Republic of)

    2011-07-15

    Thin CNF/PPy composite single-layer films were produced by the electrophoretic deposition and polymerization process which was developed for this study. It was demonstrated that the films could generate a bending motion subjected to an actuating electric voltage even though they consisted of only single-layer. Carbon nanofiber and polypyrrole composite films were obtained from only one side of a working electrode. Several different CNF/PPy films were synthesized, as varying the CNF weight ratios from 3%, 5%, and 7% to 10%. Conductivity of pure PPy and CNF/PPy composite films were measured. Conductivity of the films is improved linearly from 77.9S/cm (pure PPy film) to 124.3 S/cm (10% CNF/PPy) as the CNF weight ratio increases. Adding CNF was effective for improving the conductivity of PPy. As results of electromechanical actuation tests with the films, it was noticed that the strain of the films was reduced a little as the CNF weight ratio increased. Bending motions were observed for both PPy and CNF/PPy films subjected to a voltage. The tip bending deflections was in the range of 0.5 mm to 2 mm. CNF/PPy films showed a great potential to be a good candidate for small light actuators.

  2. Growth of carbon nanofiber coatings on nickel thin films on fused silica by catalytic thermal chemical vapor deposition: On the use of titanium, titanium–tungsten and tantalum as adhesion layers

    NARCIS (Netherlands)

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

    2009-01-01

    Coatings of carbon nanofiber (CNF) layers were synthesized on fused silica substrates using a catalytic thermal chemical vapor deposition process (C-TCVD). The effects of various adhesion layers–titanium, titanium–tungsten and tantalum–under the nickel thin film on the attachment of carbon nanofiber

  3. Superemission in vertically-aligned single-wall carbon nanotubes

    Science.gov (United States)

    Khmelinskii, Igor; Makarov, Vladimir

    2016-09-01

    Presently we used two samples of vertically aligned single-wall carbon nanotubes (VA SWCNTs) with parallelepiped geometry, sized 0.02 cm × 0.2 cm × 1.0 cm and 0.2 cm × 0.2 cm × 1.0 cm. We report absorption and emission properties of the VA SWCNTs, including strong anisotropy in both their absorption and emission spectra. We found that the emission spectra extend from the middle-IR range to the near-IR range, with such extended spectra being reported for the first time. Pumping the VA SWCNTs in the direction normal to their axis, superemission (SE) was observed in the direction along their axis. The SE band maximum is located at 7206 ± 0.4 cm-1. The energy and the power density of the superemission were estimated, along with the diffraction-limited divergence. At the pumping energy of 3 mJ/pulse, the SE energy measured by the detector was 0.74 mJ/pulse, corresponding to the total SE energy of 1.48 mJ/pulse, with the energy density of 18.5 mJ cm-2/pulse and the SE power density of 1.2 × 105 W cm-2/pulse. We report that a bundle of VA SWCNTs is an emitter with a relatively small divergence, not exceeding 3.9 × 10-3 rad. We developed a theoretical approach to explain such absorption and emission spectra. The developed theory is based on the earlier proposed SSH theory, which we extended to include the exchange interactions between the closest SWCNT neighbors. The developed theoretical ideas were implemented in a homemade FORTRAN code. This code was successfully used to calculate and reproduce the experimental spectra and to determine the SWCNT species that originate the respective absorption bands, with acceptable agreement between theory and experiment.

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

    Science.gov (United States)

    Holt, Ian; Gestmann, Ingo; Wright, Andrew C

    2013-10-01

    The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (>0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells.

  5. Fabrication of ultra thin and aligned carbon nanofibres from electrospun polyacrylonitrile nanofibres

    Indian Academy of Sciences (India)

    Javed Rafique; Jie Yu; Xiaoxiong Zha; Khalid Rafique

    2010-10-01

    Ultra thin and aligned carbon nanofibres (CNFs) have been fabricated by heat treatment from aligned polyacrylonitrile (PAN) nanofibre precursors prepared by electrospinning. The alignment of the precursor nanofibres was achieved by using a modified electrospinning set up developed recently, where a tip collector was used to collect and align the nanofibres. The average diameter of the aligned CNFs is about 80 nm. The stabilization and carbonization behaviour were studied mainly based on the randomly oriented PAN nanofibres. The effects of stabilization and carbonization temperatures, temperature-increasing rates, and with and without substrates on the morphology and structure of the CNFs were investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used to characterize the structure of the CNFs and thermogravimetric/differential temperature analysis was used to evaluate the thermal behaviour of PAN nanofibres.

  6. Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 马志斌; 王传新; 满卫东

    2005-01-01

    Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 ℃. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

  7. Optimization of a porous carbon nanofiber layer for the membrane electrode assembly in DMFC

    International Nuclear Information System (INIS)

    Highlights: • Nano-materials carbon-based electrodes are able to improve the performance of the electrodes. • Thus, this study is statistically optimizing the preparation of a CNF support for anode. • Finally, this study obtains a high performance DMFC at 21.90 mW cm−2 after the optimization. - Abstract: The performance of direct methanol fuel cells (DMFCs) is strongly influenced by the components in the membrane electrode assembly (MEA), which include a membrane, anode and cathode. The use of nano-materials to improve the performance of fuel cells has attracted the interest of researchers. The incorporation of nano-materials into these carbon-based electrodes is able to improve the performance of the electrodes. The aim of this study is to determine and optimize the parameter effecting the preparation of a nano-structured anode for high power density DMFCs. The two parameters investigated in this study were the Nafion content and the carbon loading. Both the traditional one-factor-at-a-time (OFAT) and the response surface methodology (RSM) optimization techniques were used to determine the optimum parameters. The results from the OFAT study indicated that the possible optimum levels for the Nafion content and carbon nanofiber (CNF) loading range from 2.7 to 3.5 mg cm−2 and 2.5 to 3.5 mg cm−2, respectively. A quadratic model was developed based on the RSM results, and an analysis of variance (ANOVA) showed that the model provides a good fit to the experimental data. This result indicated that the developed model successfully predicted the response with good accuracy. The maximum power density (response) was predicted and experimentally validated using the optimum composition of a 3.04 mg cm−2 Nafion content and 2.91 mg cm−2 carbon loading. The model validation revealed that the experimental value obtained under the optimum conditions (21.90 mW cm−2) was in good agreement with the values predicted by the model (22.64 mW cm−2)

  8. Production of templated carbon nano materials, carbon nanofibers and super capasitors

    OpenAIRE

    Sakintuna, Billur; Dumanlı, Ahu Gümrah; Dumanli, Ahu Gumrah; Nalbant, Aslı; Nalbant, Asli; Erden, Ayça; Erden, Ayca; Yürüm, Yuda; Yurum, Yuda

    2008-01-01

    i. Porous carbons are usually obtained via carbonization of precursors of natural or synthetic origin, followed by activation. To meet the requirements, a novel approach, the template carbonization method, has been proposed. Replication, the process of filling the external and / or internal pores of a solid with a different material, physically or chemically separating the resulting material from the template, is a technique that is widely used in microporosity and printing. Th...

  9. Bicontinuous Structure of Li₃V₂(PO₄)₃ Clustered via Carbon Nanofiber as High-Performance Cathode Material of Li-Ion Batteries.

    Science.gov (United States)

    Chen, Lin; Yan, Bo; Xu, Jing; Wang, Chunguang; Chao, Yimin; Jiang, Xuefan; Yang, Gang

    2015-07-01

    In this work, the composite structure of Li3V2(PO4)3 (LVP) nanoparticles with carbon nanofibers (CNF) is designed. The size and location of LVP particles, and the degree of graphitization and diameter of carbon nanofibers, are optimized by electrospinning and heat treatment. The bicontinuous morphologies of LVP/CNF are dependent on the carbonization of PVP and simultaneous growing of LVP, with the fibers shrunk and the LVP crystals grown toward the outside. LVP nanocystals clustered via carbon nanofibers guarantee improving the diffusion ability of Li(+), and the carbon fiber simultaneously guarantees the effective electron conductivity. Compared with the simple carbon-coated LVP and pure LVP, the particle-clustered structure guarantees high rate capability and long-life cycling stability of NF-LVP as cathode for LIBs. At 20 C rate in the range 3.0-4.3 V, NF-LVP delivers the initial capacity of 122.6 mAh g(-1) close to the theoretical value of 133 mAh g(-1), and maintains 97% of the initial capacity at the 1000th cycle. The bead-like structure of cathode material clustered via carbon nanofibers via electrospinning will be further applied to high-performance LIBs.

  10. Controlled growth of vertically aligned carbon nanotubes on metal substrates

    Science.gov (United States)

    Gao, Zhaoli

    Carbon nanotube (CNT) is a fascinating material with extraordinary electrical thermal and mechanical properties. Growing vertically aligned CNT (VACNT) arrays on metal substrates is an important step in bringing CNT into practical applications such as thermal interface materials (TIMs) and microelectrodes. However, the growth process is challenging due to the difficulties in preventing catalyst diffusion and controlling catalyst dewetting on metal substrates with physical surface heterogeneity. In this work, the catalyst diffusion mechanism and catalyst dewetting theory were studied for the controlled growth of VACNTs on metal substrates. The diffusion time of the catalyst, the diffusion coefficients for the catalyst in the substrate materials and the number density of catalyst nanoparticles after dewetting are identified as the key parameters, based on which three strategies are developed. Firstly, a fast-heating catalyst pretreatment strategy was used, aiming at preserving the amount of catalyst prior to CNT growth by reducing the catalyst diffusion time. The catalyst lifetime is extended from half an hour to one hour on a patterned Al thin film and a VACNT height of 106 mum, about twenty fold of that reported in the literature, was attained. Secondly, a diffusion barrier layer strategy is employed for a reduction of catalyst diffusion into the substrate materials. Enhancement of VACNT growth on Cu substrates was achieved by adopting a conformal Al2O 3 diffusion barrier layer fabricated by a specially designed atomic layer deposition (ALD) system. Lastly, a novel catalyst glancing angle deposition (GLAD) strategy is performed to manipulate the morphology of a relatively thick catalyst on metal substrates with physical surface heterogeneity, aiming to obtain uniform and dense catalyst nanoparticles after dewetting in the pretreatment process for enhanced VACNT growth. We are able to control the VACNT growth conditions on metal substrates in terms of their

  11. Woven Glass Fiber Composites with Aligned Carbon Nanotube Sheet Interlayers

    OpenAIRE

    Hardik Bhanushali; Philip D. Bradford

    2016-01-01

    This investigation describes the design, fabrication, and testing of woven glass fiber reinforced epoxy matrix laminates with aligned CNT sheets integrated between plies in order to improve the matrix dominated through thickness properties such as the interlaminar fracture toughness at ply interfaces. Using aligned CNT sheets allows for a concentration of millimeter long CNTs at the most likely point of laminate failure. Mode I and Mode II interlaminar fracture toughness of various CNT modifi...

  12. 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

  13. 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

    2015-07-01

    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 cm(3) 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

  14. Effect of Wrapped Carbon Nanotubes on Optical Properties, Morphology, and Thermal Stability of Electrospun Poly(vinyl alcohol Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Naoual Diouri

    2013-01-01

    Full Text Available Electrospinning was used to elaborate poly(vinyl alcohol (PVA nanofibers in the presence of embedded multiwall carbon nanotubes (MWCNTs in surfactant and polymer. MWCNTs were dispersed in aqueous solution using both sodium dodecyl sulfate (SDS as surfactant and Poly(vinyl pyrrolidone (PVP. Changing the surfactant and polymer concentration reveals that the maximum dispersion achievable is corresponding to the mass ratios MWCNTs : SDS—1 : 5 and MWCNTs : SDS : PVP—1 : 5 : 0.6 in the presence of the PVP. After the optimization of the dispersion process, the SEM image of the PVA/PVP/SDS/MWCNTs electrospun fibers presents high stability of the fibers with diameter around 224 nm. Infrared spectroscopy and thermal gravimetric analysis elucidate the type of interaction between the PVA and the coated carbon nanotube. The presence of PVP wrapped carbon nanotubes reduced slightly the onset of the degradation temperature of the electrospun nanofibers.

  15. Fe2O3 nanorods/carbon nanofibers composite: Preparation and performance as anode of high rate lithium ion battery

    Science.gov (United States)

    Wu, Chunyu; Li, Xiaoping; Li, Weishan; Li, Bin; Wang, Yaqiong; Wang, Yating; Xu, Mengqing; Xing, Lidan

    2014-04-01

    A novel Fe2O3/carbon composite is prepared using a facile one-step hydrothermal method. Its structure, morphology and performance as anode of lithium ion battery are investigated with X-ray diffraction, scanning electron microscopy, thermogravimetry, cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. It is found that the as-prepared composite is composed of α-Fe2O3 nanorods of about 75 nm in diameter and 1 μm in length, which are enwrapped with soft and curly carbon nanofibers, and exhibits superior charge/discharge performance compared to bare α-Fe2O3 nanorods, especially at high current rate. The discharge capacity is 1069 mAh g-1 at the first cycle and remains 560 mAh g-1 after 30 cycles at 0.2C for the bare nanorods, but improved to 1278 mAh g-1 and 960 mAh g-1 for the composite. At 12C, the discharge capacity is only 798 mAh g-1 initially and becomes 98 mAh g-1 after 30 cycles for the bare nanorods, while 844 mAh g-1 and 292 mAh g-1 for the composite. The improved performance of the composite is attributed to the bondage from carbon nanofibers, which contributes to the improvement in electronic conductivity and structure stability of α-Fe2O3 nanorods.

  16. An amperometric uric acid biosensor based on chitosan-carbon nanotubes electrospun nanofiber on silver nanoparticles.

    Science.gov (United States)

    Numnuam, Apon; Thavarungkul, Panote; Kanatharana, Proespichaya

    2014-06-01

    A novel amperometric uric acid biosensor was fabricated by immobilizing uricase on an electrospun nanocomposite of chitosan-carbon nanotubes nanofiber (Chi-CNTsNF) covering an electrodeposited layer of silver nanoparticles (AgNPs) on a gold electrode (uricase/Chi-CNTsNF/AgNPs/Au). The uric acid response was determined at an optimum applied potential of -0.35 V vs Ag/AgCl in a flow-injection system based on the change of the reduction current for dissolved oxygen during oxidation of uric acid by the immobilized uricase. The response was directly proportional to the uric acid concentration. Under the optimum conditions, the fabricated uric acid biosensor had a very wide linear range, 1.0-400 μmol L(-1), with a very low limit of detection of 1.0 μmol L(-1) (s/n = 3). The operational stability of the uricase/Chi-CNTsNF/AgNPs/Au biosensor (up to 205 injections) was excellent and the storage life was more than six weeks. A low Michaelis-Menten constant of 0.21 mmol L(-1) indicated that the immobilized uricase had high affinity for uric acid. The presence of potential common interfering substances, for example ascorbic acid, glucose, and lactic acid, had negligible effects on the performance of the biosensor. When used for analysis of uric acid in serum samples, the results agreed well with those obtained by use of the standard enzymatic colorimetric method (P > 0.05). PMID:24718436

  17. 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.

  18. Effects of Temperature and Catalyst Concentration on the Growth of Aligned Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaodong; LI Dan; WANG Ye; LIANG Ji

    2005-01-01

    The effects of preheating and pyrolysis temperatures and catalyst concentration on the synthesis of aligned carbon nanotubes (CNTs) using ferrocene as the catalyst and xylene as the carbon source in chemical vapor deposition were experimentally studied. The as-grown aligned CNTs were characterized by field emission scanning electron microscopy, transmission electronic microscopy, high-resolution transmission electronic microscopy, and Raman spectroscopy. The growth rate, the diameters, and the degree of crystal structure of the aligned CNTs were all found to depend on the preheating and pyrolysis temperatures and the catalyst concentration. The optimized conditions for the growth of aligned CNTs resulted in a rapid growth rate of 20.4 μm/min, with the CNTs having a good, uniform crystal structure, and clean surfaces with little amorphous carbon. The results also show that higher preheating temperatures and lower ferrocene concentrations favor the growth of single-walled CNTs.

  19. Electrocatalytic oxygen evolution reaction at a FeNi composite on a carbon nanofiber matrix in alkaline media

    Institute of Scientific and Technical Information of China (English)

    Xianghua An; Dongyoon Shin; Joey D. Ocon; Jae Kwang Lee; Young-il Son; Jaeyoung Lee

    2014-01-01

    Non-noble metals such as Fe and Ni have comparable electrocatalytic activity and stability to that of Ir and Ru in an oxygen evolution reaction (OER). In this study, we synthesized carbon nanofibers with embedded FeNi composites (FeNi-CNFs) as OER electrocatalysts by a facile route comprising electrospinning and the pyrolysis of a mixture of metal precursors and a polymer solution. FeNi-CNFs demonstrated catalytic activity and stability that were better than that of 20 wt%Ir on Vulcan carbon black in oxidizing water to produce oxygen in an alkaline media. Physicochemical and electrochemical characterization revealed that Fe and Ni had synergistic roles that enhanced OER activity by the uniform formation and widening of pores in the carbon structure, while the CNF matrix also contributed to the increased stability of the catalyst.

  20. 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.

  1. 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

    2014-12-01

    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.

  2. Woven Glass Fiber Composites with Aligned Carbon Nanotube Sheet Interlayers

    Directory of Open Access Journals (Sweden)

    Hardik Bhanushali

    2016-01-01

    Full Text Available This investigation describes the design, fabrication, and testing of woven glass fiber reinforced epoxy matrix laminates with aligned CNT sheets integrated between plies in order to improve the matrix dominated through thickness properties such as the interlaminar fracture toughness at ply interfaces. Using aligned CNT sheets allows for a concentration of millimeter long CNTs at the most likely point of laminate failure. Mode I and Mode II interlaminar fracture toughness of various CNT modified samples were investigated using double cantilever beam (DCB and end notched flexure (ENF experiments, respectively. Short beam strength (SBS and in-plane tensile properties of the CNT modified samples were also investigated. Moderate improvement was observed in Mode I and Mode II fracture toughness at crack initiation when aligned CNT sheets with a basis weight of 0.354 g/m2 were used to modify the ply interface. No compromise in the in-plane mechanical properties of the laminate was observed and very little improvement was observed in the shear related short beam strength of the CNT modified laminates as compared to the control samples. Integration of aligned CNT sheets into the composite laminate imparted in-plane and through thickness electrical properties into the nonconductive glass fiber reinforced epoxy composite laminates.

  3. Development of bimetal-grown multi-scale carbon micro-nanofibers as an immobilizing matrix for enzymes in biosensor applications

    International Nuclear Information System (INIS)

    This study describes the development of a novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers (CNFs) are grown on activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Cu and Fe as the metal catalysts. The transition metal-fiber composite is used as the working electrode of a biosensor applied to detect glucose in liquids. In such a bi-nanometal-grown multi-scale web of ACF/CNF, Cu nanoparticles adhere to the ACF-surface, whereas Fe nanoparticles used to catalyze the growth of nanofibers attach to the CNF tips. By ultrasonication, Fe nanoparticles are dislodged from the tips of the CNFs. Glucose oxidase (GOx) is subsequently immobilized on the tips by adsorption. The dispersion of Cu nanoparticles at the substrate surface results in increased conductivity, facilitating electron transfer from the glucose solution to the ACF surface during the enzymatic reaction with glucose. The prepared Cu-ACF/CNF/GOx electrode is characterized for various surface and physicochemical properties by different analytical techniques, including scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), BET surface area analysis, and transmission electron microscopy (TEM). The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by CV and calibration curves. The prepared transition metal-based carbon electrode in this study is cost-effective, simple to develop, and has a stable immobilization matrix for enzymes. - Graphical abstract: A novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode is synthesized for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers are grown on activated carbon microfibers by

  4. Development of bimetal-grown multi-scale carbon micro-nanofibers as an immobilizing matrix for enzymes in biosensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Hood, Amit R. [Department of Chemical Engineering, Indian Institute of Technology, Kanpur (India); Saurakhiya, Neelam; Deva, Dinesh [DST Unit on Nanosciences, Kanpur, 208016 (India); Sharma, Ashutosh [Department of Chemical Engineering, Indian Institute of Technology, Kanpur (India); DST Unit on Nanosciences, Kanpur, 208016 (India); Verma, Nishith, E-mail: nishith@iitk.ac.in [Department of Chemical Engineering, Indian Institute of Technology, Kanpur (India); Center for Environmental Science and Engineering, Kanpur 208016 (India)

    2013-10-15

    This study describes the development of a novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers (CNFs) are grown on activated carbon microfibers (ACFs) by chemical vapor deposition (CVD) using Cu and Fe as the metal catalysts. The transition metal-fiber composite is used as the working electrode of a biosensor applied to detect glucose in liquids. In such a bi-nanometal-grown multi-scale web of ACF/CNF, Cu nanoparticles adhere to the ACF-surface, whereas Fe nanoparticles used to catalyze the growth of nanofibers attach to the CNF tips. By ultrasonication, Fe nanoparticles are dislodged from the tips of the CNFs. Glucose oxidase (GOx) is subsequently immobilized on the tips by adsorption. The dispersion of Cu nanoparticles at the substrate surface results in increased conductivity, facilitating electron transfer from the glucose solution to the ACF surface during the enzymatic reaction with glucose. The prepared Cu-ACF/CNF/GOx electrode is characterized for various surface and physicochemical properties by different analytical techniques, including scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), BET surface area analysis, and transmission electron microscopy (TEM). The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by CV and calibration curves. The prepared transition metal-based carbon electrode in this study is cost-effective, simple to develop, and has a stable immobilization matrix for enzymes. - Graphical abstract: A novel bimetal (Fe and Cu)-grown hierarchical web of carbon micro-nanofiber-based electrode is synthesized for biosensor applications, in particular to detect glucose in liquids. Carbon nanofibers are grown on activated carbon microfibers by

  5. 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.

  6. 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.

  7. Electrospun Pd nanoparticles loaded on Vulcan carbon/ conductive polymeric ionic liquid nanofibers for selective and sensitive determination of tramadol.

    Science.gov (United States)

    Fathirad, Fariba; Mostafavi, Ali; Afzali, Daryoush

    2016-10-12

    In the present work a sensitive and selective electrochemical sensor was fabricated based on a glassy carbon electrode which has been modified with Pd nanoparticles loaded on Vulcan carbon/conductive polymeric ionic liquid composite nanofibers. The nanostructures were characterized by UV-Vis, FT-IR, FESEM, EDX and XRD techniques. The electrochemical study of the modified electrode, as well as its efficiency for the electrooxidation of tramadol was described in 0.1 M phosphate buffered solution (PBS) (pH 7.0) using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and square wave voltammetry as diagnostic techniques. It has been found that application of the composite nanofibers result in a sensitivity enhancement and a considerable decrease in the anodic overpotential, leading to negative shifts about 200 mV in peak potential. The results exhibit a linear dynamic range from 0.05 μM to 200 μM and a detection limit of 0.015 μM for tramadol. Finally, the modified electrode was used for the determination of tramadol in pharmaceutical and biological samples.

  8. Synthesis, Optimization, and Performance Demonstration of Electrospun Carbon Nanofiber-Carbon Nanotube Composite Sorbents for Point-of-Use Water Treatment.

    Science.gov (United States)

    Peter, Katherine T; Vargo, John D; Rupasinghe, Thilini P; De Jesus, Aribet; Tivanski, Alexei V; Sander, Edward A; Myung, Nosang V; Cwiertny, David M

    2016-05-11

    We developed an electrospun carbon nanofiber-carbon nanotube (CNF-CNT) composite with optimal sorption capacity and material strength for point-of-use (POU) water treatment. Synthesis variables including integration of multiwalled carbon nanotubes (CNTs) and macroporosity (via sublimation of phthalic acid), relative humidity (20 and 40%), and stabilization temperature (250 and 280 °C) were used to control nanofiber diameter and surface area (from electron microscopy and BET isotherms, respectively), surface composition (from XPS), and strength (from AFM nanoindentation and tensile strength tests). Composites were then evaluated using kinetic, isotherm, and pH-edge sorption experiments with sulfamethoxazole (log Kow = 0.89) and atrazine (log Kow = 2.61), representative micropollutants chosen for their different polarities. Although CNFs alone were poor sorbents, integration of CNTs and macroporosity achieved uptake comparable to granular activated carbon. Through reactivity comparisons with CNT dispersions, we propose that increasing macroporosity exposes the embedded CNTs, thereby enabling their role as the primary sorbent in nanofiber composites. Because the highest capacity sorbents lacked sufficient strength, our optimal formulation (polyacrylonitrile 8 wt %, CNT 2 wt %, phthalic acid 2.4 wt %; 40% relative humidity; 280 °C stabilization) represents a compromise between strength and performance. This optimized sorbent was tested with a mixture of ten organic micropollutants at environmentally relevant concentrations in a gravity-fed, flow-through filtration system, where removal trends suggest that both hydrophobic and specific binding interactions contribute to micropollutant uptake. Collectively, this work highlights the promise of CNF-CNT filters (e.g., mechanical strength, ability to harness CNT sorption capacity), while also prioritizing areas for future research and development (e.g., improved removal of highly polar micropollutants, sensitivity to

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

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuanhe; Gao, Mingxia, E-mail: gaomx@zju.edu.cn; Li, Xiang; Liu, Yongfeng; Pan, Hongge, E-mail: hgpan@zju.edu.cn

    2014-09-01

    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.

  10. Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes into Dense, Aligned Rafts

    CERN Document Server

    Wu, Justin; Antaris, Alexander; Choi, Charina L; Xie, Liming; Wu, Yingpeng; Diao, Shuo; Chen, Changxin; Chen, Yongsheng; Dai, Hongjie

    2013-01-01

    Single-walled carbon nanotubes are promising nanoelectronic materials but face long-standing challenges including production of pure semiconducting SWNTs and integration into ordered structures. Here, highly pure semiconducting single-walled carbon nanotubes are separated from bulk materials and self-assembled into densely aligned rafts driven by depletion attraction forces. Microscopy and spectroscopy revealed a high degree of alignment and a high packing density of ~100 tubes/micron within SWNT rafts. Field-effect transistors made from aligned SWNT rafts afforded short channel (~150 nm long) devices comprised of tens of purely semiconducting SWNTs derived from chemical separation within a < 1 micron channel width, achieving unprecedented high on-currents (up to ~120 microamperes per device) with high on/off ratios. The average on-current was ~ 3-4 microamperes per tube. The results demonstrated densely aligned high quality semiconducting SWNTs for integration into high performance nanoelectronics.

  11. Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kong Yuxia; Yuan Jie [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Qiu Jun, E-mail: qiujun@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials of Education of Ministry, Shanghai 201804 (China)

    2012-07-01

    Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

  12. Preparation of polyacrylnitrile (PAN)/ Manganese oxide based activated carbon nanofibers (ACNFs) for adsorption of Cadmium (II) from aqueous solution

    Science.gov (United States)

    Abdullah, N.; Yusof, N.; Jaafar, J.; Ismail, AF; Che Othman, F. E.; Hasbullah, H.; Salleh, W. N. W.; Misdan, N.

    2016-06-01

    In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) were prepared via electrospinning process. The electrospun PAN/MnO2-based ACNFs were characterised in term of its morphological structure and specific surface area using SEM and BET analysis respectively. The comparative adsorption study of cadmium (II) ions from aqueous solution between the neat ACNFs, composite ACNFs and commercial granular activated carbon was also conducted. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads with smaller fiber diameter of 437.2 nm as compared to the neat ACNFs which is 575.5 nm. BET analysis elucidated specific surface area of ACNFs/MnO2 to be 67 m2/g. Under adsorption study, it was found out that Cd (II) removal by ACNFs/MnO2 was the highest (97%) followed by neat ACNFs (96%) and GAC (74%).

  13. Glutathione modified screen-printed carbon nanofiber electrode for the voltammetric determination of metal ions in natural samples.

    Science.gov (United States)

    Pérez-Ràfols, Clara; Serrano, Núria; Díaz-Cruz, José Manuel; Ariño, Cristina; Esteban, Miquel

    2016-08-01

    This work reports the development of a glutathione modified electrode via electrografting on a screen-printed carbon nanofiber substrate (GSH-SPCNFE). GSH-SPCNFE was compared to a classical screen-printed carbon electrode modified with glutathione (GSH-SPCE) for the simultaneous voltammetric determination of Cd(II) and Pb(II). Their electrochemical characterization and analytical performance suggest that SPCNFE could be a much better support for GSH immobilization. The applicability of GSH-SPCNFE for the determination of low concentration levels of Pb(II) and Cd(II) ions in environmental samples was successfully tested in a certified wastewater reference material by means of stripping voltammetry with a very high reproducibility and good trueness. PMID:27216650

  14. Highly flexible NiCo2O4/CNTs doped carbon nanofibers for CO2 adsorption and supercapacitor electrodes.

    Science.gov (United States)

    Iqbal, Nousheen; Wang, Xianfeng; Ahmed Babar, Aijaz; Yu, Jianyong; Ding, Bin

    2016-08-15

    Controllable synthesis of carbon nanofibers (CNFs) with hierarchical porosity and high flexibility are extremely desirable for CO2 adsorption and energy storage applications. Herein, we report a nickel cobaltite/carbon nanotubes doped CNFs (NiCo2O4/CNTs CNFs) mesoporous membrane that shows well-developed flexibility, tailored pore structure, hydrophobic character, and high stability. Ascribed to these unique features, NiCo2O4/CNTs CNFs membrane shows high CO2 capture of 1.54mmol/g at 25°C and 1.0bar, and electrochemical measurements for supercapacitors exhibit good performance with specific capacitances of 220F/g (in 1M KOH) at a current density of 1A/g. The successful synthesis of such hybrid membrane provides new insight into development of various multifunctional applications. PMID:27209394

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

    Science.gov (United States)

    Aboueloyoun Taha, Ahmed

    2015-12-01

    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.

  16. 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.

  17. Effects of increasing carbon nanofiber density in polyurethane composites for inhibiting bladder cancer cell functions.

    Science.gov (United States)

    Tsang, Melissa; Chun, Young Wook; Im, Yeon Min; Khang, Dongwoo; Webster, Thomas J

    2011-07-01

    Polyurethane (PU) is a versatile elastomer that is commonly used in biomedical applications. In turn, materials derived from nanotechnology, specifically carbon nanofibers (CNFs), have received increasing attention for their potential use in biomedical applications. Recent studies have shown that the dispersion of CNFs in PU significantly enhances composite nanoscale surface roughness, tensile properties, and thermal stability. Although there have been studies concerning normal primary cell functions on such nanocomposites, there have been few studies detailing cancer cell responses. Since many patients who require bladder transplants have suffered from bladder cancer, the ideal bladder prosthetic material should not only promote normal primary human urothelial cell (HUC) function, but also inhibit the return of bladder cancerous cell activity. This study examined the correlation between transitional (UMUC) and squamous (or SCaBER) urothelial carcinoma cells and HUC on PU:CNF nanocomposites of varying PU and CNF weight ratios (from pure PU to 4:1 [PU:CNF volume ratios], 2:1, 1:1, 1:2, and 1:4 composites to pure CNF). Composites were characterized for mechanical properties, wettability, surface roughness, and chemical composition by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and goniometry. The adhesion and proliferation of UMUC and SCaBER cancer cells were assessed by MTS assays. Cellular responses were further quantified by measuring the amounts of nuclear mitotic protein 22 (NMP-22), vascular endothelial growth factor (VEGF), and tumor necrosis factor alpha. Results demonstrated that both UMUC and SCaBER cell proliferation rates decreased over time on substrates with increased CNF in PU. In addition, with the exception of VEGF from UMUC (which was the same across all materials), composites containing the most CNF activated cancer cells (UMUC and SCaBER) the least, as shown by

  18. Self-fabrication of 3D Patterns on Aligned Carbon Nanotubes Films

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Because of its outstanding performance, an aligned nanotube film with micropatterns has been a research focus in the field of nano-science and technology. Although quite a number of researchers have been successful in constructing such patterns, the precondition for the success, until recently, is to obtain the patterned substrates in advance.A research group at the CAS Institute of Chemistry (ICCAS) has succeeded in self-assembly of threedimensional (3-D) micropatterns on aligned carbon nanotube films.

  19. Effect of Particle Density on the Aligned Growth of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Sheng-gao; WANG Jian-hua; HAN Jian-jun

    2004-01-01

    Aligned carbon nanotubes (CNTs) were prepared on Ni-coated Ni substrate by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at temperature of 550℃.The experimental results show a direct correlation between the alignment of CNTs and the density of the catalyst particles at low temperature.When the particle density is high enough,among CNTs there are strong interactions that can inhibit CNTs from growing randomly.The crowding effect among dense CNTs results in the aligned growth of CNTs at low temperature.

  20. 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.

  1. Imaging, Spectroscopic, Mechanical and Biocompatibility Studies of Electrospun Tecoflex(®) EG 80A Nanofibers and Composites Thereof Containing Multiwalled Carbon Nanotubes.

    Science.gov (United States)

    Macossay, Javier; Sheikh, Faheem A; Cantu, Travis; Eubanks, Thomas M; Salinas, M Esther; Farhangi, Chakavak S; Ahmad, Hassan; Hassan, M Shamshi; Khil, Myung-Seob; Maffi, Shivani K; Kim, Hern; Bowlin, Gary L

    2014-12-01

    The present study discusses the design, development and characterization of electrospun Tecoflex(®) EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C-N and N-H bonds in polyurethanes are responsible for the interactions with MWCNTs. Furthermore, tensile testing indicated an increase in the Young's modulus of the nanofibers as the MWCNTs concentration was increased. Finally, NIH 3T3 fibroblasts were seeded on the obtained nanofibers, demonstrating cell biocompatibility and proliferation. Therefore, the results indicate the successful formation of polyurethane nanofibers with enhanced mechanical properties, and demonstrate their biocompatibility, suggesting their potential application in biomedical areas. PMID:25435600

  2. Synthesis and characterization of well-aligned carbon nitrogen nanotubes by microwave plasma chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Well-aligned carbon nitrogen nanotube films have been synthesized successfully on mesoporous silica substrates by microwave plasma chemical vapor deposition (MWPCVD) method. Studies on their morphology, structure, and composition by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX), respectively, indicate that these nanotubes consist of linearly polymerized carbon nitrogen nanobells, and the nitrogen atoms have been doped into carbon netweork to form a new structure C1-xNx (x=0.16±0.01). X-ray photoelectron spectroscopy (XPS) results of the samples further demonstrate that carbon bonds covalently with nitrogen in all the carbon nitrogen nanotube films.

  3. Si-Carbon Composite Nanofibers with Good scalability and Favorable Architecture for Highly Reversible Lithium Storage and Superb Kinetics

    International Nuclear Information System (INIS)

    We demonstrate a simple electrospinning for preparing Si-carbon composite Nanofiber (NF) in which aciniform aggregates of Si particles are well encased by amorphous carbon. The Si-carbon composite NF exhibit a significantly improved electrochemical performance with a high specific capacity of 1250 mAh·g−1 and a superior cycling performance during 50 cycles at a rate of 0.2 C. More importantly, Si-carbon composite NF maintain about 70% of initial capacity at 0.2 C and an excellent cycling stability even at 25 times higher current density compared to the initial condition, proving that it has superb kinetics compared to ever reported Si or SiOx materials. The electrochemical superiority of Si-carbon composite NF can be attributed to amorphous carbon framework accommodating the inherent volume expansion of Si during lithiation as well as the enlarged contact area between active materials and conducting agent attributed to the morphological characteristics of its one dimensional (1D) nanostructure

  4. Aligned carbon nanotubes physics, concepts, fabrication and devices

    CERN Document Server

    Ren, Zhifeng; Wang, Yang

    2012-01-01

    This book surveys the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. The text illustrates major fabrication methods in detail, particularly the most widely used PECVD growth techniques.

  5. Carbon-Confined SnO2-Electrodeposited Porous Carbon Nanofiber Composite as High-Capacity Sodium-Ion Battery Anode Material.

    Science.gov (United States)

    Dirican, Mahmut; Lu, Yao; Ge, Yeqian; Yildiz, Ozkan; Zhang, Xiangwu

    2015-08-26

    Sodium resources are inexpensive and abundant, and hence, sodium-ion batteries are promising alternative to lithium-ion batteries. However, lower energy density and poor cycling stability of current sodium-ion batteries prevent their practical implementation for future smart power grid and stationary storage applications. Tin oxides (SnO2) can be potentially used as a high-capacity anode material for future sodium-ion batteries, and they have the advantages of high sodium storage capacity, high abundance, and low toxicity. However, SnO2-based anodes still cannot be used in practical sodium-ion batteries because they experience large volume changes during repetitive charge and discharge cycles. Such large volume changes lead to severe pulverization of the active material and loss of electrical contact between the SnO2 and carbon conductor, which in turn result in rapid capacity loss during cycling. Here, we introduce a new amorphous carbon-coated SnO2-electrodeposited porous carbon nanofiber (PCNF@SnO2@C) composite that not only has high sodium storage capability, but also maintains its structural integrity while ongoing repetitive cycles. Electrochemical results revealed that this SnO2-containing nanofiber composite anode had excellent electrochemical performance including high-capacity (374 mAh g(-1)), good capacity retention (82.7%), and large Coulombic efficiency (98.9% after 100th cycle). PMID:26252051

  6. 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. PMID:23755586

  7. Preparation and characterization of aligned carbon nanotubes coated with titania nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YU Hongtao; ZHAO Huimin; QUAN Xie; CHEN Shuo

    2006-01-01

    Well-aligned carbon nanotubes coated with titania (TiO2) were prepared by atmospheric pressure chemical vapor deposition (APCVD), and the sequential experiments including carbon nanotubes preparation, air-oxidation purification and titania nanoparticles coating were performed at different temperatures in the same reactor. Scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction patterns (XRD), and energy- dispersive X-ray spectra (EDX) demonstrated the well-aligned nanotubes and TiO2 nanoparticles in close proximity and the average diameter of TiO2 nanoparticles was 11.5 nm.

  8. Immobilization of CoCl2 (cobalt chloride) on PAN (polyacrylonitrile) composite nanofiber mesh filled with carbon nanotubes for hydrogen production from hydrolysis of NaBH4 (sodium borohydride)

    International Nuclear Information System (INIS)

    Composite nanofiber sheets containing multiwalled carbon nanotubes and cobalt chloride dispersed in PAN (polyacrylonitrile) were produced by an electrospinning technique. The synthesized PAN/CoCl2/CNTs composite nanofiber was used as the catalyst for hydrogen production from the hydrolysis of sodium borohydride. FT-IR characterization showed that the pretreated CNTs possess different organic functional groups which help improve the compatibility between CNTs and PAN organic polymer. SEM (scanning electron microscopy), TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray technique) were used to characterize the composite nanofiber and it was found that CNTs can be coaxially dispersed into the PAN nanofiber. During the hydrolysis of NaBH4, this PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity compared to the composite without CNTs doping. Kinetic analysis of NaBH4 hydrolysis shows that the reaction of NaBH4 hydrolysis based on this catalyst can be ascribed to the first-order reaction and the activation energy of the catalyst was approximately 52.857 kJ/mol. Meanwhile, the composite nanofiber catalyst shows excellent stability and reusability in the recycling experiment. - Highlights: • Composite nanofiber sheets were prepared via electrospinning. • PAN (polyacrylonitrile)/CoCl2 (cobalt chloride)/CNTs (carbon nanotubes) nanofiber was used as the catalyst for hydrogen production. • CNTs can be coaxially dispersed into the PAN nanofiber. • PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity. • The composite nanofiber catalyst shows excellent stability and reusability

  9. Dynamic finite element analysis of the crack-inclusion interaction in aligned CNF composites under impact loading conditions

    Science.gov (United States)

    Ting, Huat Tung

    The interaction between a crack and an inclusion of microfiber in an aligned carbon nanofiber (CNF) toughened composite under impact loading conditions was studied by using dynamic finite element analysis (FEA). The nanocomposite material used in this study was T300/Epon 862 enhanced with aligned carbon nanofibers (CNFs). The dynamic stress intensity factors (DSIFs) were evaluated to describe the dynamic fracture behavior of the fracture model. In this study, a numerical homogenization model using FEA was first employed to determine the effective material properties of the equivalent matrix material of Epon 862 and aligned CNFs. The effects of T300 microfiber inclusion eccentricity and CNF alignment angle on the DSIFs were examined in this study. The displacement extrapolation method for monoclinic materials was utilized to calculate the DSIFs. The numerical results demonstrated a mechanism known as "crack-tip shielding" and demonstrated that the CNF alignment angle has an impact on the DSIFs.

  10. Pulse gas alignment and AFM manipulation of single-wall carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    TIAN XiaoJun; WANG YueChao; XI Ning; DONG ZaiLi; TUNG Steve

    2008-01-01

    In the fabrication process of nanoelectronic device arrays based on single-wall carbon nanotube (SWCNT), oriented alignment of SWCNTs and property modification of metallic SWCNTs in the array are the key problems to be solved. Pulse gas alignment with substrate downward tilt is proposed to realize the controllable alignment of SWCNTs. Experimental results demonstrate that 84% SWCNTs are aligned in -15°- 15° angular to the pulse gas direction. A modified nanomanipulation technology based on atomic force microscope (AFM) is utilized to perform various kinds of SWCNT manipulation, such as SWCNT separation from the "Y" CNT, catalyst removal from the SWCNT end, continual nano buckles fabrication on SWCNT and even stretching to break, which provides a feasible way to modify the size, shape and the electrical property of SWCNTs.

  11. 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.

  12. 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.

  13. Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films.

    Science.gov (United States)

    Won, Yoonjin; Gao, Yuan; Panzer, Matthew A; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W; Cai, Wei; Goodson, Kenneth E

    2013-12-17

    Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies--from thermal solar to automotive waste heat recovery systems--whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties.

  14. Fabrication of Aligned Carbon Nanotube/Polycaprolactone/Gelatin Nanofibrous Matrices for Schwann Cell Immobilization

    OpenAIRE

    Shiao-Wen Tsai; Chun-Chiang Huang; Lih-Rou Rau; Fu-Yin Hsu

    2014-01-01

    In this study, we utilized a mandrel rotating collector consisting of two parallel, electrically conductive pieces of tape to fabricate aligned electrospun polycaprolactone/gelatin (PG) and carbon nanotube/polycaprolactone/gelatin (PGC) nanofibrous matrices. Furthermore, we examined the biological performance of the PGC nanofibrous and film matrices using an in vitro culture of RT4-D6P2T rat Schwann cells. Using cell adhesion tests, we found that carbon nanotube inhibited Schwann cell attach...

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

    International Nuclear Information System (INIS)

    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 m2/g. • The mats were surface-deposited with Ag nanoparticles via the scCO2 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 CO2 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

  16. Carbon Nanofibers Synthesized on Selective Substrates for Nonvolatile Memory and 3D Electronics

    Science.gov (United States)

    Kaul, Anupama B.; Khan, Abdur R.

    2011-01-01

    A plasma-enhanced chemical vapor deposition (PECVD) growth technique has been developed where the choice of starting substrate was found to influence the electrical characteristics of the resulting carbon nanofiber (CNF) tubes. It has been determined that, if the tubes are grown on refractory metallic nitride substrates, then the resulting tubes formed with dc PECVD are also electrically conducting. Individual CNFs were formed by first patterning Ni catalyst islands using ebeam evaporation and liftoff. The CNFs were then synthesized using dc PECVD with C2H2:NH3 = [1:4] at 5 Torr and 700 C, and approximately equal to 200-W plasma power. Tubes were grown directly on degenerately doped silicon substrates with resistivity rho approximately equal to 1-5 meterohm-centimeter, as well as NbTiN. The approximately equal to 200-nanometer thick refractory NbTiN deposited using magnetron sputtering had rho approximately equal to 113 microohm-centimeter and was also chemically compatible with CNF synthesis. The sample was then mounted on a 45 beveled Al holder, and placed inside a SEM (scanning electron microscope). A nanomanipulator probe stage was placed inside the SEM equipped with an electrical feed-through, where tungsten probes were used to make two-terminal electrical measurements with an HP 4156C parameter analyzer. The positive terminal nanoprobe was mechanically manipulated to physically contact an individual CNF grown directly on NbTiN as shown by the SEM image in the inset of figure (a), while the negative terminal was grounded to the substrate. This revealed the tube was electrically conductive, although measureable currents could not be detected until approximately equal to 6 V, after which point current increased sharply until compliance (approximately equal to 50 nA) was reached at approximately equal to 9.5 V. A native oxide on the tungsten probe tips may contribute to a tunnel barrier, which could be the reason for the suppressed transport at low biases

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

    OpenAIRE

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

    2013-01-01

    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. W...

  18. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide

    Science.gov (United States)

    Leyva-Porras, César; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.; Avila-Vega, Yazmín I.; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  19. Characteristics and Electrochemical Performance of Si-Carbon Nanofibers Composite as Anode Material for Binder-Free Lithium Secondary Batteries.

    Science.gov (United States)

    Hyun, Yura; Park, Heai-Ku; Park, Ho-Seon; Lee, Chang-Seop

    2015-11-01

    The carbon nanofibers (CNFs) and Si-CNFs composite were synthesized using a chemical vapor deposition (CVD) method with an iron-copper catalyst and silicon-covered Ni foam. Acetylene as a carbon source was flowed into the quartz reactor of a tubular furnace heated to 600 degrees C. This temperature was maintained for 10 min to synthesize the CNFs. The morphologies, compositions, and crystal quality of the prepared CNFs were characterized by Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the Si-CNFs composite as an anode of the Li secondary batteries were investigated using a three-electrode cell. The as-deposited Si-CNF composite on the Ni foam was directly employed as an working electrode without any binder, and lithium foil was used as the counter and reference electrode. A glass fiber separator was used as the separator membrane. Two kinds of electrolytes were employed; 1) 1 M LiPF6 was dissolved in a mixture of EC (ethylene carbonate): PC (propylene carbonate): EMC (Ethyl methyl carbonate) in a 1:1:1 volume ratio and 2) 1 M LiClO4 was dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge-discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. The resulting Si-CNFs composite achieved the large discharge capacity of 613 mAh/g and much improved cycle-ability with the retention rate of 87% after 20 cycles.

  20. Synergistic effect of carbon nanofiber/nanotube composite catalyst on carbon felt electrode for high-performance all-vanadium redox flow battery.

    Science.gov (United States)

    Park, Minjoon; Jung, Yang-jae; Kim, Jungyun; Lee, Ho il; Cho, Jeaphil

    2013-10-01

    Carbon nanofiber/nanotube (CNF/CNT) composite catalysts grown on carbon felt (CF), prepared from a simple way involving the thermal decomposition of acetylene gas over Ni catalysts, are studied as electrode materials in a vanadium redox flow battery. The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples among the samples prepared at 500, 600, 700, and 800 °C. Moreover, this composite electrode in the full cell exhibits substantially improved discharge capacity and energy efficiency by ~64% and by ~25% at 40 mA·cm(-2) and 100 mA·cm(-2), respectively, compared to untreated CF electrode. This outstanding performance is due to the enhanced surface defect sites of exposed edge plane in CNF and a fast electron transfer rate of in-plane side wall of the CNT.

  1. Vertically aligned carbon nanotubes for sensing unidirectional fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Kiani, Keivan, E-mail: k_kiani@kntu.ac.ir

    2015-05-15

    From applied mechanics points of view, potential application of ensembles of single-walled carbon nanotubes (SWCNTs) as fluid flow sensors is aimed to be examined. To this end, useful nonlocal analytical and numerical models are developed. The deflection of the ensemble of SWCNTs at the tip is introduced as a measure of its sensitivity. The influences of the length and radius of the SWCNT, intertube distance, fluid flow velocity, and distance of the ensemble from the leading edge of the rigid base on the deflection field of the ensemble are comprehensively examined. The obtained results display how calibration of an ensemble of SWCNTs can be methodically carried out in accordance with the characteristics of the ensemble and the external fluid flow.

  2. Study on the preparation of polyacrylontrile-based carbon nanofibers by solution blowing%溶液喷射法制备聚丙烯腈基纳米碳纤维的研究

    Institute of Scientific and Technical Information of China (English)

    杨小灿; 庄旭品; 史少俊; 程博闻; 康卫民

    2013-01-01

    采用溶液喷射法制备了聚丙烯腈(PAN)纳米纤维,探讨了纺丝工艺参数对纤维形貌和直径的影响,优化了纺丝工艺,制得了直径分布为160~380 nm的PAN纳米纤维;经260℃空气氛围预氧化,900℃氮气氛围碳化,对得到的纤维的结构和形貌进行了表征,结果表明得到了平均直径为170 nm的纳米碳纤维.%Carbon nanofibers were prepared by blowing of polyacrylonitrile (PAN) solution, and following stabilization and carbonization treatment. The effect of spinning parameters, including PAN concentration, air-blowing pressure, and solution injecting rate, on the morphology of nanofibers precursor were investigated. After oxidized in 260 °C air and carbonized in 900 °C He, nanocarbon fibers were manufactured. The morphology and structure of PAN nanofibers, preoxidized nanofibers and carbonized nanofibers were characterized. The result showed that spinning parameters played important role in determining the dominating structure of product morphology, and carbon nanofibers with diameters of 100~340 nm were produced.

  3. The precise self-assembly of individual carbon nanotubes using magnetic capturing and fluidic alignment

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Joon S; Rust, Michael J; Do, Jaephil; Ahn, Chong H [Department of Electrical and Computer Engineering, Microsystems and BioMEMS Laboratory, University of Cincinnati, Cincinnati, OH 45221 (United States); Yun, Yeo-Heung; Schulz, Mark J [Department of Mechanical Engineering, University of Cincinnati, 45221 (United States); Shanov, Vesselin, E-mail: chong.ahn@uc.ed [Department of Chemical and Materials Engineering, University of Cincinnati, 45221 (United States)

    2009-08-12

    A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nanobiosensors.

  4. 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.

  5. 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.

  6. Magnetic properties of NiFe{sub 2}O{sub 4}/carbon nanofibers from Venezuelan petcoke

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cañizales, Edgard [Área de Análisis Químico Inorgánico, PDVSA, INTEVEP, Los Teques 1070-A (Venezuela, Bolivarian Republic of)

    2015-05-01

    NiFe{sub 2}O{sub 4}/carbon nanofibers (NiFe{sub 2}O{sub 4}/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe{sub 2}O{sub 4} as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe{sub 2}O{sub 4}/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs. - Highlights: • NiFe{sub 2}O{sub 4}/CNFs have been synthesized by hydrothermal method using petroleum coke. • Nickel ferrite nanoparticles were used as the catalyst. • HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. • The size of the nanoparticles defines the diameter of the CNFs.

  7. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nataraj, S.K.; Kim, B.H.; Yun, J.H.; Lee, D.H.; Aminabhavi, T.M. [Carbon Materials Lab, Faculty of Applied Chemical Engineering/Alan G. MacDiarmid Energy Research Institute (AMERI), Chonnam National University, Gwangju 500-757 (Korea, Republic of); Yang, K.S. [Carbon Materials Lab, Faculty of Applied Chemical Engineering/Alan G. MacDiarmid Energy Research Institute (AMERI), Chonnam National University, Gwangju 500-757 (Korea, Republic of)], E-mail: ksyang@chonnam.ac.kr

    2009-05-25

    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.

  9. Effects of potassium on Ni-K/Al2O3 catalysts in the synthesis of carbon nanofibers by catalytic hydrogenation of CO2.

    Science.gov (United States)

    Chen, Ching S; Lin, Jarrn H; You, Jiann H; Yang, Kuo H

    2010-03-25

    Commercially available Ni/Al(2)O(3) samples containing various concentrations of potassium were used to achieve carbon deposition from CO(2) via catalytic hydrogenation. Experimental results show that K additives can induce the formation of carbon nanofibers or carbon deposition on Ni/Al(2)O(3) during the reverse water-gas shift reaction. This work proposes that the formation rate of carbon deposition depends closely on ensemble control, suggesting that the ensemble size necessary to form carbon may be approximately 0.5 potassium atoms. The results of CO(2) temperature-programmed desorption provide strong evidence that the new adsorption sites for CO(2) created on Ni-K/Al(2)O(3) closely depend upon the synthesis of carbon nanofibers. It is found that some potassium-related active phases obtained by calcination and reduction pretreatments can participate in the carbon deposition reaction. The formation pathway for carbon deposition suggests that the main source of carbon deposition is CO(2) and that the pathway is independent of the reaction products CO and CH(4) in the reverse water-gas shift reaction. PMID:19655780

  10. 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

  11. Self crimped and aligned fibers

    Directory of Open Access Journals (Sweden)

    Thinakaran Senthilram

    2011-05-01

    Full Text Available Electrospinning is one of the most successful means of producing nanofibers with enormous application potential. New methods of producing nanofibers without high voltages are presently being explored by researchers around the globe. In the present work, a facile method of producing aligned and crimped fibers with polycaprolactone by rotating the needle assembly is described.

  12. A novel nonenzymatic sensor based on CuO nanoneedle/graphene/carbon nanofiber modified electrode for probing glucose in saliva.

    Science.gov (United States)

    Ye, Daixin; Liang, Guohai; Li, Huixiang; Luo, Juan; Zhang, Song; Chen, Hui; Kong, Jilie

    2013-11-15

    Here, we report on a novel nonenzymatic amperometric glucose sensor based on CuO nanoneedle/graphene/carbon nanofiber modified electrode. The results of the scanning electron microscopy indicate that electronic network was formed through their direct binding with the graphene/carbon nanofiber, which leads to larger active surface areas and faster electron transfer for the glucose sensor. High electrocatalytic activity toward the oxidation of glucose was observed with a rapid response (<2 s), a low detection limit (0.1 µM), a wide and useful linear range (1-5.3 mM) as well as good stability and repeatability. Moreover, the common interfering species, such as ascorbic acid, uric acid, dopamine and so forth did not cause obvious interference. The sensor can also be used for quantification of glucose concentration in real saliva samples. Therefore, this work has demonstrated a simple and effective sensing platform for nonenzymatic detection of glucose. PMID:24148397

  13. 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.

  14. Study on the Electrospun CNTs/Polyacrylonitrile-Based Nanofiber Composites

    OpenAIRE

    Bo Qiao; Xuejia Ding; Xiaoxiao Hou; Sizhu Wu

    2011-01-01

    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 o...

  15. CVD-grown horizontally aligned single-walled carbon nanotubes: synthesis routes and growth mechanisms.

    Science.gov (United States)

    Ibrahim, Imad; Bachmatiuk, Alicja; Warner, Jamie H; Büchner, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H

    2012-07-01

    Single-walled carbon nanotubes (SWCNTs) have attractive electrical and physical properties, which make them very promising for use in various applications. For some applications however, in particular those involving electronics, SWCNTs need to be synthesized with a high degree of control with respect to yield, length, alignment, diameter, and chirality. With this in mind, a great deal of effort is being directed to the precision control of vertically and horizontally aligned nanotubes. In this review the focus is on the latter, horizontally aligned tubes grown by chemical vapor deposition (CVD). The reader is provided with an in-depth review of the established vapor deposition orientation techniques. Detailed discussions on the characterization routes, growth parameters, and growth mechanisms are also provided. PMID:22619167

  16. Synthesis and characterization of well-aligned carbon nitrogen nanotubes by microwave plasma chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    马旭村; 徐贵昌; 王恩哥

    2000-01-01

    Well-aligned carbon nitrogen nanotube films have been synthesized successfully on meso-porous silica substrates by microwave plasma chemical vapor deposition (MWPCVD) method. Studies on their morphology, structure, and composition by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX), respectively, indicate that these nanotubes consist of linearly polymerized carbon nitrogen nanobells, and the nitrogen atoms have been doped into carbon netweork to form a new structure C1-xNx( x = 0.16±0.01). X-ray photoelectron spectroscopy (XPS) results of the samples further demonstrate that carbon bonds cova-lently with nitrogen in all the carbon nitrogen nanotube films.

  17. Estimation of the poly (ε-caprolactone [PCL] and α-cyclodextrin [α-CD] stoichiometric ratios in their inclusion complexes [ICs], and evaluation of porosity and fiber alignment in PCL nanofibers containing these ICs

    Directory of Open Access Journals (Sweden)

    Ganesh Narayanan

    2015-12-01

    Full Text Available This paper describes the utilization of Proton-Nuclear Magnetic Resonance spectroscopy (1H NMR to quantify the stoichiometric ratios between poly (ε-caprolactone [PCL] and α-cyclodextrin (α-CD present in their non-stoichiometric inclusion complexes [(n-s-ICs]. This paper further describes the porosity and fiber alignment of PCL nanofibers nucleated by the [(n-s-ICs] during electrospinning. 1H NMR indicated that the two non-stoichiometric inclusion complexes utilized in this study had differing stoichiometric ratios that were closely similar to those of the starting ratios used to make them. Studies on porosity and fiber alignments were conducted on the scanning electron microscope images using ImageJ. The data indicates that both fiber alignment as well as porosity values remain almost the same over all the samples. Thus we can conclude the improvement in mechanical properties was due only to the loading of the ICs, and their subsequent interaction with bulk unthreaded PCL.

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

    Science.gov (United States)

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

    2012-11-16

    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. PMID:23090569

  19. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes.

    Science.gov (United States)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M; Hároz, Erik H; Doorn, Stephen K; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M; Adams, W Wade; Hauge, Robert H; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm(2)) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 10(6) nanotubes in a cross-sectional area of 1 μm(2). The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios. PMID:27043199

  20. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    Science.gov (United States)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  1. Parallel and orthogonal E-field alignment of single-walled carbon nanotubes by ac dielectrophoresis

    International Nuclear Information System (INIS)

    We designed planar electrodes, for dielectrophoretic manipulation of single-walled carbon nanotubes (SWNTs), built as metal-oxide-semiconductor nanogap capacitors with common substrate and oxide thicknesses of 17 and 150 nm. Such design generates high electric fields (109 V m-1) and also the fringing field is curved due to the conducting substrate, unlike fields generated by conventionally used planar electrodes. Scanning electron microscopy images showed SWNTs aligned parallel and perpendicular to the electrodes. Raman spectroscopic mapping was used to produce separate images of the metallic (m-SWNT) and semiconducting (s-SWNT) nanotube density distributions. As expected, parallel alignment of the m-SWNTs with the E-field was found; however, also a perpendicular alignment of s-SWNTs was observed. Such orthogonal alignment of s-SWNTs is a rare observation and has not been experimentally reported before in detail with Raman images. Due to the unique electrode design, we were able to obtain substantial separation of m-SWNTs and s-SWNTs. Numerical modeling of the electric field factor of the dielectrophoresis force was done, and it matched perfectly with the experimental results. The orthogonal alignment of s-SWNTs results from comparable values of parallel and perpendicular polarizability to the nanotube axis.

  2. 纳米纤维束的制备及力学性能研究%Fabrication of braided wires from aligned nanofibers and analysis of their mechanical performance

    Institute of Scientific and Technical Information of China (English)

    胡雯; 黄争鸣

    2009-01-01

    PU nanofibers were fabricated by means of electrospinning and were collected undirectionally using a rotating disk. The relationship between a rotating speed and fiber alignment was studied. The collected fiber bundles were post processing treated using the techniques such as heating, stretching, twisting, and preforming, before they were made into a braided wire. Optimal post processing parameters were obtained in order to achieve the highest mechanical properties for the fiber bundles. It was shown that the braided wires had a much better mechanical performance than that of the unidirectionally collected fiber bundles before the post treatments, and even better than that after the treatments. This high mechanical behavior implies that the braided wires based on aligned electrospun nanofibers will have potential applications in textile and biomedical fields.%采用静电纺丝法制备出了纳米级、亚微米级纤维,采用尖角圆盘收集成具有定向排列的单向纤维束,考察了圆盘转速对纤维定向性的影响.为提高纤维的强度和模量,对收集到的纤维束进行了热处理、拉伸、加捻、定型等后处理工艺,再将多股定型的纤维束编织成线.研究了上述工艺参数对纤维束力学性能的影响,选取最佳工艺参数编织纤维束,并研究了编织线的力学性能.良好的性能预示其在纺织、生物医学等领域具有潜在的应用前景.

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

    Science.gov (United States)

    Matsuda, Keita; Norimatsu, Wataru; Arai, Shigeo; Kusunoki, Michiko

    2016-10-01

    We observed and analyzed the behavior of platinum nanoparticles (PtNPs) supported on aligned-carbon nanotubes (CNTs) at high temperatures by X-ray photoelectron spectroscopy and high-resolution transmission electron microscope observations. We found that the PtNPs moved toward the inner-side along each CNT on which they were deposited. The mechanism of this behavior is related to the redox reaction of Pt with the carbon atoms in the CNT. We also performed in-situ observation of this process at a high temperature using an environmental transmission electron microscope under an oxygen atmosphere. We found that the PtNPs penetrated down into a high-density aligned CNT forest along the tube axis and that the PtNPs changed their shape to fit the structure of the CNTs during their movement.

  4. Hierarchical Electrospun and Cooperatively Assembled Nanoporous Ni/NiO/MnOx/Carbon Nanofiber Composites for Lithium Ion Battery Anodes.

    Science.gov (United States)

    Bhaway, Sarang M; Chen, Yu-Ming; Guo, Yuanhao; Tangvijitsakul, Pattarasai; Soucek, Mark D; Cakmak, Miko; Zhu, Yu; Vogt, Bryan D

    2016-08-01

    A facile method to fabricate hierarchically structured fiber composites is described based on the electrospinning of a dope containing nickel and manganese nitrate salts, citric acid, phenolic resin, and an amphiphilic block copolymer. Carbonization of these fiber mats at 800 °C generates metallic Ni-encapsulated NiO/MnOx/carbon composite fibers with average BET surface area (150 m(2)/g) almost 3 times higher than those reported for nonporous metal oxide nanofibers. The average diameter (∼900 nm) of these fiber composites is nearly invariant of chemical composition and can be easily tuned by the dope concentration and electrospinning conditions. The metallic Ni nanoparticle encapsulation of NiO/MnOx/C fibers leads to enhanced electrical conductivity of the fibers, while the block copolymers template an internal nanoporous morphology and the carbon in these composite fibers helps to accommodate volumetric changes during charging. These attributes can lead to lithium ion battery anodes with decent rate performance and long-term cycle stability, but performance strongly depends on the composition of the composite fibers. The composite fibers produced from a dope where the metal nitrate is 66% Ni generates the anode that exhibits the highest reversible specific capacity at high rate for any composition, even when including the mass of the nonactive carbon and Ni(0) in the calculation of the capacity. On the basis of the active oxides alone, near-theoretical capacity and excellent cycling stability are achieved for this composition. These cooperatively assembled hierarchical composites provide a platform for fundamentally assessing compositional dependencies for electrochemical performance. Moreover, this electrospinning strategy is readily scalable for the fabrication of a wide variety of nanoporous transition metal oxide fibers.

  5. Hierarchical Electrospun and Cooperatively Assembled Nanoporous Ni/NiO/MnOx/Carbon Nanofiber Composites for Lithium Ion Battery Anodes.

    Science.gov (United States)

    Bhaway, Sarang M; Chen, Yu-Ming; Guo, Yuanhao; Tangvijitsakul, Pattarasai; Soucek, Mark D; Cakmak, Miko; Zhu, Yu; Vogt, Bryan D

    2016-08-01

    A facile method to fabricate hierarchically structured fiber composites is described based on the electrospinning of a dope containing nickel and manganese nitrate salts, citric acid, phenolic resin, and an amphiphilic block copolymer. Carbonization of these fiber mats at 800 °C generates metallic Ni-encapsulated NiO/MnOx/carbon composite fibers with average BET surface area (150 m(2)/g) almost 3 times higher than those reported for nonporous metal oxide nanofibers. The average diameter (∼900 nm) of these fiber composites is nearly invariant of chemical composition and can be easily tuned by the dope concentration and electrospinning conditions. The metallic Ni nanoparticle encapsulation of NiO/MnOx/C fibers leads to enhanced electrical conductivity of the fibers, while the block copolymers template an internal nanoporous morphology and the carbon in these composite fibers helps to accommodate volumetric changes during charging. These attributes can lead to lithium ion battery anodes with decent rate performance and long-term cycle stability, but performance strongly depends on the composition of the composite fibers. The composite fibers produced from a dope where the metal nitrate is 66% Ni generates the anode that exhibits the highest reversible specific capacity at high rate for any composition, even when including the mass of the nonactive carbon and Ni(0) in the calculation of the capacity. On the basis of the active oxides alone, near-theoretical capacity and excellent cycling stability are achieved for this composition. These cooperatively assembled hierarchical composites provide a platform for fundamentally assessing compositional dependencies for electrochemical performance. Moreover, this electrospinning strategy is readily scalable for the fabrication of a wide variety of nanoporous transition metal oxide fibers. PMID:27399605

  6. Pressure Effects on the Atomic and Electronic Structure of Aligned Small Diameter Carbon Nanotubes

    OpenAIRE

    Saxena, Sumit; Trevor A. Tyson

    2008-01-01

    Density functional methods have been used to calculate the electronic properties of aligned smalldiameter single-walled carbon nanotubes under hydrostatic pressures. Abrupt pressure induced semiconductor-metal and metal-semiconductor transitions concomitant with changes in structure are observed. Novel and unexpected unit cell nanotube cross-sections are found. These tubes are observed to form interlinking structures at very high pressures. The large changes in electronic structure and the ab...

  7. Aligned short fibre hybrid composites with virgin and recycled carbon fibres

    OpenAIRE

    Longana, Marco L.; Yu, Hana; Potter, Kevin D.

    2015-01-01

    One of the main problems in industrial applications of carbon composite materials is recycling end of life products. Usually chopped recycled fibres are randomly dispersed in materials as low-grade additives for non-structural applications; however, in order to maximize economic and functional viability, these fibres should be reused as reinforcement for high performance structural composites. The fibre alignment level is the key factor to increase the fibre volume fraction, and consequently ...

  8. Dielectrophoresis Aligned Single-Walled Carbon Nanotubes as pH Sensors

    OpenAIRE

    Wei Xue; Kan Kan Yeung; Martin, Caleb M.; Pengfei Li

    2011-01-01

    Here we report the fabrication and characterization of pH sensors using aligned single-walled carbon nanotubes (SWNTs). The SWNTs are dispersed in deionized (DI) water after chemical functionalization and filtration. They are deposited and organized on silicon substrates with the dielectrophoresis process. Electrodes with “teeth”-like patterns—fabricated with photolithography and wet etching—are used to generate concentrated electric fields and strong dielectrophoretic forces for the SWNTs to...

  9. Alignment of Multi-walled Carbon Nanotubes in Polyacrylonitrile Fibers by Mechanical Drawing

    Institute of Scientific and Technical Information of China (English)

    WANG Biao; WEN Zhi-wei; PENG Kun; WANG Hua-ping

    2010-01-01

    Polyacrylonitrile(PAN)/multi-waUed carbon nanotubes(MWNTs)narmcomposites were prepared by an in-situ polymerization method and the fibers from these composites were obtained by a wet-spinning process.The orientation behavior of MWNTs in the PAN fibers was investigated by X-ray diffraction and sound velocity methods.The dispersion and the alignment of the nanotubes were also studied by scanning electron microscopy.

  10. 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.

  11. Nitrogen-Doped Carbon Nanoparticle-Carbon Nanofiber Composite as an Efficient Metal-Free Cathode Catalyst for Oxygen Reduction Reaction.

    Science.gov (United States)

    Panomsuwan, Gasidit; Saito, Nagahiro; Ishizaki, Takahiro

    2016-03-23

    Metal-free nitrogen-doped carbon materials are currently considered at the forefront of potential alternative cathode catalysts for the oxygen reduction reaction (ORR) in fuel cell technology. Despite numerous efforts in this area over the past decade, rational design and development of a new catalyst system based on nitrogen-doped carbon materials via an innovative approach still present intriguing challenges in ORR catalysis research. Herein, a new kind of nitrogen-doped carbon nanoparticle-carbon nanofiber (NCNP-CNF) composite with highly efficient and stable ORR catalytic activity has been developed via a new approach assisted by a solution plasma process. The integration of NCNPs and CNFs by the solution plasma process can lead to a unique morphological feature and modify physicochemical properties. The NCNP-CNF composite exhibits a significantly enhanced ORR activity through a dominant four-electron pathway in an alkaline solution. The enhancement in ORR activity of NCNP-CNF composite can be attributed to the synergistic effects of good electron transport from highly graphitized CNFs as well as abundance of exposed catalytic sites and meso/macroporosity from NCNPs. More importantly, NCNP-CNF composite reveals excellent long-term durability and high tolerance to methanol crossover compared with those of a commercial 20 wt % supported on Vulcan XC-72. We expect that NCNP-CNF composite prepared by this synthetic approach can be a promising metal-free cathode catalyst candidate for ORR in fuel cells and metal-air batteries. PMID:26908214

  12. Aligned multi-walled carbon nanotube-reinforced composites: processing and mechanical characterization

    International Nuclear Information System (INIS)

    Carbon nanotubes have been the subject of considerable attention because of their exceptional physical and mechanical properties. These properties observed at the nanoscale have motivated researchers to utilize carbon nanotubes as reinforcement in composite materials. In this research, a micro-scale twin-screw extruder was used to achieve dispersion of multi-walled carbon nanotubes in a polystyrene matrix. Highly aligned nanocomposite films were produced by extruding the polymer melt through a rectangular die and drawing the film prior to cooling. Randomly oriented nanocomposites were produced by achieving dispersion first with the twin-screw extruder followed by pressing a film using a hydraulic press. The tensile behaviour of the aligned and random nanocomposite films with 5 wt.{%} loading of nanotubes were characterized. Addition of nanotubes increased the tensile modulus, yield strength and ultimate strengths of the polymer films, and the improvement in elastic modulus with the aligned nanotube composite is five times greater than the improvement for the randomly oriented composite. (author)

  13. RAPID COMMUNICATION: Aligned multi-walled carbon nanotube-reinforced composites: processing and mechanical characterization

    Science.gov (United States)

    Thostenson, Erik T.; Chou, Tsu-Wei

    2002-08-01

    Carbon nanotubes have been the subject of considerable attention because of their exceptional physical and mechanical properties. These properties observed at the nanoscale have motivated researchers to utilize carbon nanotubes as reinforcement in composite materials. In this research, a micro-scale twin-screw extruder was used to achieve dispersion of multi-walled carbon nanotubes in a polystyrene matrix. Highly aligned nanocomposite films were produced by extruding the polymer melt through a rectangular die and drawing the film prior to cooling. Randomly oriented nanocomposites were produced by achieving dispersion first with the twin-screw extruder followed by pressing a film using a hydraulic press. The tensile behaviour of the aligned and random nanocomposite films with 5 wt.{%} loading of nanotubes were characterized. Addition of nanotubes increased the tensile modulus, yield strength and ultimate strengths of the polymer films, and the improvement in elastic modulus with the aligned nanotube composite is five times greater than the improvement for the randomly oriented composite.

  14. 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.

  15. 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.

  16. Aerosynthesis: Growth of Vertically-aligned Carbon Nanofibres with Air DC Plasma

    Directory of Open Access Journals (Sweden)

    A. Kodumagulla

    2014-03-01

    Full Text Available Vertically-aligned carbon nanofibres (VACNFs have been synthesized in a mixture of acetone and air using catalytic DC plasma-enhanced chemical vapour deposition. Typically, ammonia or hydrogen is used as an etchant gas in the mixture to remove carbon that otherwise passivates the catalyst surface and impedes growth. Our demonstration of the use of air as the etchant gas opens up the possibility that ion etching could be sufficient to maintain the catalytic activity state during synthesis. It also demonstrates a path toward growing VACNFs in the open atmosphere.

  17. Scalable synthesis of aligned carbon nanotubes bundles using green natural precursor: neem oil

    OpenAIRE

    Kumar, Rajesh; Tiwari, Radhey Shyam; Srivastava, Onkar Nath

    2011-01-01

    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 t...

  18. Adaptive Neuro-Fuzzy Modeling of Mechanical Behavior for Vertically Aligned Carbon Nanotube Turfs

    Institute of Scientific and Technical Information of China (English)

    Mohammad A1-Khedher; Charles Pezeshki; Jeanne McHale; GFritz Knorr

    2011-01-01

    Several characterization methods have been developed to investigate the mechanical and structural properties of vertically aligned carbon nanotubes (VACNTs). Establishing analytical models at nanoscale to interpret these properties is complicated due to the nonuniformity and irregularity in quality of as-grown samples.In this paper, we propose a new methodology to investigate the correlation between indentation resistance of multi-wall carbon nanotube (MWCNT) turfs, Raman spectra and the geometrical properties of the turf structure using adaptive neuro-fuzzy phenomenological modeling. This methodology yields a novel approach for modeling at the nanoscale by evaluating the effect of structural morphologies on nanomaterial properties using Raman spectroscopy.

  19. 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.

  20. 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. PMID:27082129

  1. Quantum dot decorated aligned carbon nanotube bundles for a performance enhanced photoswitch

    Science.gov (United States)

    Sreejith, Sivaramapanicker; Hansen, Reinack; Joshi, Hrishikesh; Kutty, R. Govindan; Liu, Zheng; Zheng, Lianxi; Yang, Jinglei; Zhao, Yanli

    2016-04-01

    Photoactive materials that are triggered by the irradiation of light to generate an electrical response provide an ecofriendly platform to afford efficient power sources and switches. A chemical assembly of well-known elements with aligned carbon nanotube bundles is reported here, which was employed to form an efficient photo-induced charge transfer device. The primary elements of this device are ultra-long multi-walled carbon nanotube (MWCNT) bundles, polyaniline (PANI) thin film coating, and CdSe quantum dots (QDs). Highly ordered and horizontally aligned MWCNT bundles were coated with PANI to enhance charge transfer properties of active QDs in this platform. The obtained device (CdSe-MWCNT@PANI) constructed on a silicon base exhibits highly efficient power conversion capabilities owing to the aligned MWCNT bundle assisted enhanced charge transport pathways generated within the device. The device also shows a short circuit current density (Jsc) of 9.81 mA cm-2 and an open circuit voltage (Voc) of 0.46 V. The power conversion efficiency (PCE) of the device is 5.41%, and the current response is quite stable, highly responsive, and reproducible.Photoactive materials that are triggered by the irradiation of light to generate an electrical response provide an ecofriendly platform to afford efficient power sources and switches. A chemical assembly of well-known elements with aligned carbon nanotube bundles is reported here, which was employed to form an efficient photo-induced charge transfer device. The primary elements of this device are ultra-long multi-walled carbon nanotube (MWCNT) bundles, polyaniline (PANI) thin film coating, and CdSe quantum dots (QDs). Highly ordered and horizontally aligned MWCNT bundles were coated with PANI to enhance charge transfer properties of active QDs in this platform. The obtained device (CdSe-MWCNT@PANI) constructed on a silicon base exhibits highly efficient power conversion capabilities owing to the aligned MWCNT bundle assisted

  2. 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.

  3. Crystallographic growth and alignment of carbon nanotubes on few-layer graphene

    Science.gov (United States)

    Arash, Aram; Hunley, Patrick D.; Nasseri, Mohsen; Boland, Mathias J.; Sundararajan, Abhishek; Hudak, Bethany M.; Guiton, Beth S.; Strachan, Douglas R.

    2015-03-01

    Hybrid carbon nanotube and graphene structures are emerging as an exciting material system built from a common sp2 carbon backbone. Such hybrid systems have promise for use in improving the performance of energy storage and high-speed electronic applications. Towards the attainment of such hybrid materials, the catalytic growth and crystallographic alignment of these integrated structures are investigated along with the atomic-scale features of their interfaces. The catalytic activity of nanoparticles to form carbon nanotubes on the surface of few-layer graphene is tuned through precise feedstock application. Through careful materials synthesis, the interfaces of these hybrid carbon nanotube - graphene systems are investigated through ultra-high resolution electron microscopy.

  4. Effects of reaction conditions on hydrogen production and carbon nanofiber properties generated by methane decomposition in a fixed bed reactor using a NiCuAl catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suelves, I.; Pinilla, J.L.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma Castan, 4, 50015 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Marie Curie 2, 28049 Madrid (Spain)

    2009-07-01

    In this paper, the results obtained in the catalytic decomposition of methane in a fixed bed reactor using a NiCuAl catalyst prepared by the fusion method are presented. The influences of reaction temperature and space velocity on hydrogen concentration in the outlet gases, as well as on the properties of the carbon produced, have been investigated. Reaction temperature and the space velocity both increase the reaction rate of methane decomposition, but also cause an increase in the rate of catalyst deactivation. Under the operating conditions used, the carbon product is mainly deposited as nanofibers with textural properties highly correlated with the degree of crystallinity. (author)

  5. 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.

  6. Synthesis of palladium/helical carbon nanofiber hybrid nanostructures and their application for hydrogen peroxide and glucose detection.

    Science.gov (United States)

    Jia, Xueen; Hu, Guangzhi; Nitze, Florian; Barzegar, Hamid Reza; Sharifi, Tiva; Tai, Cheuk-Wai; Wågberg, Thomas

    2013-11-27

    We report on a novel sensing platform for H2O2 and glucose based on immobilization of palladium-helical carbon nanofiber (Pd-HCNF) hybrid nanostructures and glucose oxidase (GOx) with Nafion on a glassy carbon electrode (GCE). HCNFs were synthesized by a chemical vapor deposition process on a C60-supported Pd catalyst. Pd-HCNF nanocomposites were prepared by a one-step reduction free method in dimethylformamide (DMF). The prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The Nafion/Pd-HCNF/GCE sensor exhibits excellent electrocatalytic sensitivity toward H2O2 (315 mA M(-1) cm(-2)) as probed by cyclic voltammetry (CV) and chronoamperometry. We show that Pd-HCNF-modified electrodes significantly reduce the overpotential and enhance the electron transfer rate. A linear range from 5.0 μM to 2.1 mM with a detection limit of 3.0 μM (based on the S/N = 3) and good reproducibility were obtained. Furthermore, a sensing platform for glucose was prepared by immobilizing the Pd-HCNFs and glucose oxidase (GOx) with Nafion on a glassy carbon electrode. The resulting biosensor exhibits a good response to glucose with a wide linear range (0.06-6.0 mM) with a detection limit of 0.03 mM and a sensitivity of 13 mA M(-1) cm(-2). We show that small size and homogeneous distribution of the Pd nanoparticles in combination with good conductivity and large surface area of the HCNFs lead to a H2O2 and glucose sensing platform that performs in the top range of the herein reported sensor platforms. PMID:24180258

  7. Factoring-in agglomeration of carbon nanotubes and nanofibers for better prediction of their toxicity versus asbestos

    Directory of Open Access Journals (Sweden)

    Murray Ashley R

    2012-04-01

    Full Text Available Abstract Background Carbon nanotubes (CNT and carbon nanofibers (CNF are allotropes of carbon featuring fibrous morphology. The dimensions and high aspect ratio of CNT and CNF have prompted the comparison with naturally occurring asbestos fibers which are known to be extremely pathogenic. While the toxicity and hazardous outcomes elicited by airborne exposure to single-walled CNT or asbestos have been widely reported, very limited data are currently available describing adverse effects of respirable CNF. Results Here, we assessed pulmonary inflammation, fibrosis, oxidative stress markers and systemic immune responses to respirable CNF in comparison to single-walled CNT (SWCNT and asbestos. Pulmonary inflammatory and fibrogenic responses to CNF, SWCNT and asbestos varied depending upon the agglomeration state of the particles/fibers. Foci of granulomatous lesions and collagen deposition were associated with dense particle-like SWCNT agglomerates, while no granuloma formation was found following exposure to fiber-like CNF or asbestos. The average thickness of the alveolar connective tissue - a marker of interstitial fibrosis - was increased 28 days post SWCNT, CNF or asbestos exposure. Exposure to SWCNT, CNF or asbestos resulted in oxidative stress evidenced by accumulations of 4-HNE and carbonylated proteins in the lung tissues. Additionally, local inflammatory and fibrogenic responses were accompanied by modified systemic immunity, as documented by decreased proliferation of splenic T cells ex vivo on day 28 post exposure. The accuracies of assessments of effective surface area for asbestos, SWCNT and CNF (based on geometrical analysis of their agglomeration versus estimates of mass dose and number of particles were compared as predictors of toxicological outcomes. Conclusions We provide evidence that effective surface area along with mass dose rather than specific surface area or particle number are significantly correlated with toxicological

  8. Adsorption Behavior and Mechanism of Antibiotic Sulfamethoxazole on Carboxylic-Functionalized Carbon Nanofibers-Encapsulated Ni Magnetic Nanoparticles.

    Science.gov (United States)

    Lan, Yi K; Chen, Tse C; Tsai, Hsing J; Wu, Hung C; Lin, Jarrn H; Lin, I K; Lee, Jyh F; Chen, Ching S

    2016-09-20

    In this work we developed a one-step process for synthesizing carboxylic-functionalized carbon nanofibers (CNFs)-encapsulated Ni magnetic nanoparticles (Ni@CNFs) that exhibit an excellent magnetic response and a large content of hydrophilic carboxylate groups with a negative charge (RCOO(-)) on the carbon surface. The carbon-encapsulated magnetic Ni nanoparticles could be rapidly separated from water, and they showed high efficiency for adsorption of the antibiotic sulfamethoxazole (SMX) in aqueous solution. The adsorption of SMX on Ni@CNFs as a function of pH was investigated, and the greatest adsorption occurred at pH 7.0. The adsorption isotherms for SMX on Ni@CNFs depended on different pH values. A Monte Carlo simulation was used to probe the relationship between molecular conformation and π-π interaction. The high adsorption of SMX on Ni@CNFs at pH 7.0 could be ascribed to deprotonated SMX being easily converted to a planar-like conformation, thereby resulting in the formation of π rings that were approximately parallel to the graphite surface and that enhanced strong π-π interaction. Electrostatic and π-π interactions both contributed to deprotonated SMX adsorption at pH 7.0, and they influenced the adsorption isotherm toward the Freundlich model. However, in weakly acidic environments (pH 2.0 and 4.0), the electrostatic interaction alone could induce an adsorption pattern that was similar to the Langmuir model. PMID:27578402

  9. Activated mesoporous carbon nanofibers fabricated using water etching-assisted templating for high-performance electrochemical capacitors.

    Science.gov (United States)

    An, Geon-Hyoung; Koo, Bon-Ryul; Ahn, Hyo-Jin

    2016-03-01

    Activated mesoporous carbon nanofibers (AMCNFs) are synthesized by a sequential process of electrospinning, water etching-assisted templating, and acid treatment. Their morphologies, crystal structures, melting behavior, chemical bonding states, surface properties, and electrochemical performance are investigated for three different polyacrylonitrile (PAN) to polyvinylpyrrolidone (PVP) weight ratios - PAN : PVP = 8 : 2, 7 : 3, and 6 : 4. Compared to other samples, the AMCNFs with an optimum weight ratio of 6 : 4 show the highest specific surface area of 692 m(2) g(-1), a high volume percentage of mesopores of 43.9%, and an increased amount of carboxyl groups (10.5%). This results in a high specific capacitance of 207 F g(-1), a high-rate capability with a capacitance retention of 93%, a high energy density of 24.8-23.1 W h kg(-1), and an excellent cycling durability of up to 3000 cycles. The electrochemical performance improvement can be explained by the combined effect of the high surface area relative to the increased electrical double-layers, the high volume fraction of mesopores relative to shorter diffusion routes and low resistance pathways for ions, and the increased amount of carboxyl groups on the CNF surface relative to enhanced wettability.

  10. COx-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

    Institute of Scientific and Technical Information of China (English)

    Siang-Piao Chai; Sharif Hussein Sharif Zein; Abdul Rahman Mohamed

    2006-01-01

    Direct decomposition of methane was carried out using a fixed-bed reactor at 700 ℃ for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2catalysts (where M=AgO, CoO, CuO, FeO, MnOx and MoO) in methane decomposition was investigated.The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiO2 support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2(w/w) since the highest yield of hydrogen was obtained over this catalyst.

  11. Alumina-carbon nanofibers nanocomposites obtained by spark plasma sintering for proton exchange membrane fuel cell bipolar plates

    Energy Technology Data Exchange (ETDEWEB)

    Borrell, A.; Torrecillas, R. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN) Consejo Superior de Investigaciones Cientificas, Universidad de Oviedo, Principado de Asturias, Parque Tecnologico de Asturias, Llanera Asturias (Spain); Rocha, V.G.; Fernandez, A. [ITMA Materials Technology, Parque Tecnologico de Asturias, Llanera Asturias (Spain)

    2012-08-15

    There is an increasing demand of multifunctional materials for a wide variety of technological developments. Bipolar plates for proton exchange membrane fuel cells are an example of complex functionality components that must show among other properties high mechanical strength, electrical, and thermal conductivity. The present research explored the possibility of using alumina-carbon nanofibers (CNFs) nanocomposites for this purpose. In this study, it was studied for the first time the whole range of powder compositions in this system. Homogeneous powders mixtures were prepared and subsequently sintered by spark plasma sintering. The materials obtained were thoroughly characterized and compared in terms of properties required to be used as bipolar plates. The control on material microstructure and composition allows designing materials where mechanical or electrical performances are enhanced. A 50/50 vol.% alumina-CNFs composite appears to be a very promising material for this kind of application. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Flexible carbon nanofiber/polyvinylidene fluoride composite membranes as interlayers in high-performance Lithiumsbnd Sulfur batteries

    Science.gov (United States)

    Wang, Zhenhua; Zhang, Jing; Yang, Yuxiang; Yue, Xinyang; Hao, Xiaoming; Sun, Wang; Rooney, David; Sun, Kening

    2016-10-01

    Traditionally polyvinylidene fluoride membranes have been used in applications such as membrane distillation, wastewater treatment, desalination and separator fabrication. Within this work we demonstrate that a novel carbon nanofiber/polyvinylidene fluoride (CNF/PVDF) composite membrane can be used as an interlayer for Lithiumsbnd Sulfur (Lisbnd S) batteries yielding both high capacity and long cycling life. This PVDF membrane is shown to effectively separate dissolved lithium polysulfide with the high electronic conductivity CNF not only reducing the internal resistance in the sulfur cathode but also helping immobilize the polysulfide through its abundant nanospaces. The resulting Lisbnd S battery assembled with the CNF/PVDF composite membrane effectively solves the polysulfide permeation problem and exhibits excellent electrochemical performance. It is further shown that the CNF/PVDF electrode has an excellent cycling stability and retains a capacity of 768.6 mAh g-1 with a coulombic efficiency above 99% over 200 cycles at 0.5C, which is more than twice that of a cell without CNF/PVDF (374 mAh g-1). In addition, the low-cost raw materials and the simple preparation process of CNF/PVDF composite membrane is also amenable for industrial production.

  13. Ultrasensitive Bisphenol A Field-Effect Transistor Sensor Using an Aptamer-Modified Multichannel Carbon Nanofiber Transducer.

    Science.gov (United States)

    Kim, Sung Gun; Lee, Jun Seop; Jun, Jaemoon; Shin, Dong Hoon; Jang, Jyongsik

    2016-03-01

    Bisphenol A (BPA) is a known endocrine-disrupting compound (EDC) that has a structure similar to that of the hormone estrogen. Even low concentrations of BPA are able to bind estrogen receptors, thereby inducing severe diseases such as reproductive disorders, chronic diseases, and various types of cancer. Despite such serious effects, the use of BPA remains widespread. Therefore, monitoring of both dietary and nondietary exposure to BPA is important for human healthcare. Herein, we present a field-effect transistor (FET) sensor using aptamer-modified multichannel carbon nanofibers (MCNFs) to detect BPA. The MCNFs are fabricated via single-nozzle electrospinning of two immiscible polymer solutions followed by thermal treatment in an inert atmosphere. The MCNFs are then oxidized using a solution of HNO3 and H2SO4 to introduce carboxyl groups on the surface of the fibers. The carboxyl-functionalized MCNFs (CMCNFs) are immobilized on an amine-functionalized electrode substrate by forming a covalent bond, and amine-functionalized BPA-binding aptamers are modified in the same manner on the CMCNFs. The resulting FET sensors exhibit a high sensitivity, as well as specificity toward BPA at an unprecedentedly low concentration of 1 fM. Furthermore, these sensors are stable and could be reused for repeated assays. PMID:26883578

  14. Ultrafine TiO2 Decorated Carbon Nanofibers as Multifunctional Interlayer for High-Performance Lithium-Sulfur Battery.

    Science.gov (United States)

    Liang, Gemeng; Wu, Junxiong; Qin, Xianying; Liu, Ming; Li, Qing; He, Yan-Bing; Kim, Jang-Kyo; Li, Baohua; Kang, Feiyu

    2016-09-01

    Although lithium-sulfur (Li-S) batteries deliver high specific energy densities, lots of intrinsic and fatal obstacles still restrict their practical application. Electrospun carbon nanofibers (CNFs) decorated with ultrafine TiO2 nanoparticles (CNF-T) were prepared and used as a multifunctional interlayer to suppress the volume expansion and shuttle effect of Li-S battery. With this strategy, the CNF network with abundant space and superior conductivity can accommodate and recycle the dissolved polysulfides for the bare sulfur cathode. Meanwhile, the ultrafine TiO2 nanoparticles on CNFs work as anchoring points to capture the polysulfides with the strong interaction, making the battery perform with remarkable and stable electrochemical properties. As a result, the Li-S battery with the CNF-T interlayer delivers an initial reversible capacity of 935 mA h g(-1) at 1 C with a capacity retention of 74.2% after 500 cycles. It is believed that this simple, low-cost and scalable method will definitely bring a novel perspective on the practical utilization of Li-S batteries. PMID:27508357

  15. Magnetite (Fe3O4)-filled carbon nanofibers as electro-conducting/superparamagnetic nanohybrids and their multifunctional polymer composites

    International Nuclear Information System (INIS)

    A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe3O4 nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields

  16. 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.

  17. The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

    Directory of Open Access Journals (Sweden)

    Liao CZ

    2014-03-01

    Full Text Available Cheng Zhu Liao,1,2 Hoi Man Wong,3 Kelvin Wai Kwok Yeung,3 Sie Chin Tjong2 1Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, People's Republic of China; 2Department of Physics and Materials Science, City University of Hong Kong, 3Department of Orthopedics and Traumatology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Abstract: This study focuses on the design, fabrication, microstructural and property characterization, and biocompatibility evaluation of polypropylene (PP reinforced with carbon nanofiber (CNF and hydroxyapatite nanorod (HANR fillers. The purpose is to develop advanced PP/CNF–HANR hybrids with good mechanical behavior, thermal stability, and excellent biocompatibility for use as craniofacial implants in orthopedics. Several material-examination techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and impact measurement are used to characterize the microstructural, mechanical, and thermal properties of the hybrids. Furthermore, osteoblastic cell cultivation and colorimetric assay are also employed for assessing their viability on the composites. The CNF and HANR filler hybridization yields an improvement in Young's modulus, impact strength, thermal stability, and biocompatibility of PP. The PP/2% CNF–20% HANR hybrid composite is found to exhibit the highest elastic modulus, tensile strength, thermal stability, and biocompatibility. Keywords: nanocomposite, implant, cellular viability, mechanical behavior

  18. Co-production of hydrogen and carbon nanofibers from methane decomposition over zeolite Y supported Ni catalysts

    International Nuclear Information System (INIS)

    Highlights: • Methane cracking requires an optimum temperature range of 550–600 °C for H2 yield. • At 550 and 600 °C, catalyst showed longer activity for the whole test. • At 600 °C, a 614.25 gc/gNi of carbon was obtained using 30% Ni/Y zeolite catalysts. • Produced filamentous carbon has the same diameter as the metallic nickel itself. • VHSV has reverse and non-linear relevancy to the weight of Ni/Y zeolite catalyst. - Abstract: The objective of this paper is to study the influences of different operating conditions on the hydrogen formation and properties of accumulated carbon from methane decomposition using zeolite Y supported 15% and 30% Ni, respectively, at a temperature range between 500 and 650 °C in a pilot scale fixed bed reactor. The temperature ramp was showed a significant impact on the thermo-catalytic decomposition (TCD) of methane. An optimum temperature range of 550–600 °C were required to attain the maximum amount of methane conversion and revealed that at 550 and 600 °C, catalyst showed longer activity for the whole studied of experimental runs. Additionally, at 550 °C, the methane decomposition is two times longer for 30% Ni/Y zeolite than that for 15% Ni/Y zeolite catalyst, whereas it is almost three times higher at 500 °C. A maximum carbon yield of 614.25 and 157.54 gc/gNi were reported after end of the complete reaction at 600 °C with 30% and 15% Ni/Y zeolite catalyst, respectively. From BET, TPD, and XRD analysis, we had reported that how the chemistry between the TCD of methane and metal content of the catalysts could significantly affect the hydrogen production as well as carbon nano-fibers. TEM analysis ensured that the produced carbon had fishbone type structures with a hollow core and grew from crystallites of Ni anchored on the external surface of the catalysts and irrespective of the metal loadings, the whisker types of nano filaments were formed as confirmed from FESEM analysis. Nevertheless, the effect of

  19. 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.

  20. 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.

  1. Challenges in process integration of catalytic DC plasma synthesis of vertically aligned carbon nanofibres

    Energy Technology Data Exchange (ETDEWEB)

    Melechko, Anatoli V; Pearce, Ryan C [Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Hensley, Dale K; Simpson, Michael L [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); McKnight, Timothy E, E-mail: anatoli_melechko@ncsu.edu [Measurement Science and Systems Engineering Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)

    2011-05-04

    The ability to synthesize free-standing, individual carbon nanofibres (CNFs) aligned perpendicularly to a substrate has enabled fabrication of a large array of devices with nanoscale functional elements, including electron field emission sources, electrochemical probes, neural interface arrays, scanning probes, gene delivery arrays and many others. This was made possible by development of a catalytic plasma process, with DC bias directing the alignment of nanofibres. Successful implementation of prototypical devices has uncovered numerous challenges in the integration of this synthesis process as one of the steps in device fabrication. This paper is dedicated to these engineering and fundamental difficulties that hinder further device development. Relatively high temperature for catalytic synthesis, electrical conductivity of the substrate to maintain DC discharge and other difficulties place restrictions on substrate material. Balancing non-catalytic carbon film deposition and substrate etching, non-uniformity of plasma due to growth of the high aspect ratio structures, plasma instabilities and other factors lead to challenges in controlling the plasma. Ultimately, controlling the atomistic processes at the catalyst nanoparticle (NP) and the behaviour of the NP is the central challenge of plasma nanosynthesis of vertically aligned CNFs.

  2. Nonhomogeneous morphology and the elastic modulus of aligned carbon nanotube films

    International Nuclear Information System (INIS)

    Carbon nanotube (CNT) arrays offer the potential to develop nanostructured materials that leverage their outstanding physical properties. Vertically aligned carbon nanotubes (VACNTs), also named CNT forests, CNT arrays, or CNT turfs, can provide high heat conductivity and sufficient mechanical compliance to accommodate thermal expansion mismatch for use as thermal interface materials (TIMs). This paper reports measurements of the in-plane moduli of vertically aligned, single-walled CNT (SWCNT) and multi-walled CNT (MWCNT) films. The mechanical response of these films is related to the nonhomogeneous morphology of the grown nanotubes, such as entangled nanotubes of a top crust layer, aligned CNTs in the middle region, and CNTs in the bottom layer. To investigate how the entanglements govern the overall mechanical moduli of CNT films, we remove the crust layer consisting of CNT entanglements by etching the CNT films from the top. A microfabricated cantilever technique shows that crust removal reduces the resulting moduli of the etched SWCNT films by as much as 40%, whereas the moduli of the etched MWCNT films do not change significantly, suggesting a minimal crust effect on the film modulus for thick MWCNT films (>90 μm). This improved understanding will allow us to engineer the mechanical moduli of CNT films for TIMs or packaging applications. (paper)

  3. 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.

  4. Bottom-up tailoring of photonic nanofibers

    DEFF Research Database (Denmark)

    Balzer, Frank; Madsen, Morten; Frese, Ralf;

    2008-01-01

    Aligned ensembles of nanoscopic nanofibers from organic molecules such as para-phenylenes for photonic applications can be fabricated by self-assembled molecular growth on a suited dielectric substrate. Epitaxy together with alignment due to electric surface fields determines the growth directions...

  5. Effect of aligned carbon nanotubes on electrical conductivity behaviour in polycarbonate matrix

    Indian Academy of Sciences (India)

    M M Larijani; E J Khamse; Z Asadollahi; M Asadi

    2012-06-01

    This article reports effects of alignment of embedded carbon nanotubes in a polycarbonate polymer matrix under magnetic, direct and alternating current electric fields on the electrical properties of the resulting nanocomposites. Composites consisting of different quantities of carbon nanotubes in a polycarbonate matrix have been prepared using a solution casting technique. The effects of field strength and nanotube concentration on the resulted network structure and conductivity of the composites were studied by in situ optical microscopy, transmission electron microscopy and four-point probe technique. The results showed that the composites prepared in the presence of field had better conductivity than those of as-prepared composites. It was also concluded that the application of alternating current electric field and magnetic field in this system led to the formation of relatively continuing networks while direct current electric field only prevented agglomeration of the carbon nanotubes in the polycarbonate matrix and created relatively uniform distribution of nanotubes in the matrix.

  6. Charge trapping in aligned single-walled carbon nanotube arrays induced by ionizing radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Esqueda, Ivan S., E-mail: isanchez@isi.edu [Information Sciences Institute, University of Southern California, Arlington, Virginia 22203 (United States); Cress, Cory D. [Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375 (United States); Che, Yuchi; Cao, Yu; Zhou, Chongwu [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States)

    2014-02-07

    The effects of near-interfacial trapping induced by ionizing radiation exposure of aligned single-walled carbon nanotube (SWCNT) arrays are investigated via measurements of gate hysteresis in the transfer characteristics of aligned SWCNT field-effect transistors. Gate hysteresis is attributed to charge injection (i.e., trapping) from the SWCNTs into radiation-induced traps in regions near the SWCNT/dielectric interface. Self-consistent calculations of surface-potential, carrier density, and trapped charge are used to describe hysteresis as a function of ionizing radiation exposure. Hysteresis width (h) and its dependence on gate sweep range are investigated analytically. The effects of non-uniform trap energy distributions on the relationship between hysteresis, gate sweep range, and total ionizing dose are demonstrated with simulations and verified experimentally.

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

    Science.gov (United States)

    Boulanger, P.; Belkadi, L.; Descarpentries, J.; Porterat, D.; Hibert, E.; Brouzes, A.; Mille, M.; Patel, S.; Pinault, M.; Reynaud, C.; Mayne-L'Hermite, M.; Decamps, J. M.

    2013-04-01

    We present the main results demonstrating the feasibility of high surface (> A4 format size) semi-industrial fabrication of composites embedding VACNT in organic matrices. The process of growing VACNT exhibits several advantages regarding safety issues: integrating de facto a safe collecting procedure on the substrate, avoiding additional preparation steps and simplifying handling and protection by impregnation into a matrix. The following steps of the overall process: VACNT carpet functionalization, alignment control and impregnation, can be processed on-line in a closed and safe continuous process and lead to dramatically reduced direct nanotube exposure for workers and users. This project opens the route to a continuous, roll-to-roll, safer, cost-effective and green industrial process to manufacture composites with controlled and aligned greener "black" carbon nanotubes.

  8. Electrospun Nanofibers for Neural and Tissue Engineering

    Science.gov (United States)

    Xia, Younan

    2009-03-01

    Electrospinning has been exploited for almost one century to process polymers and other materials into nanofibers with controllable compositions, diameters, porosities, and porous structures for a variety of applications. Owing to its small size, high porosity, and large surface area, a nonwoven mat of electrospun nanofibers can serve as an ideal scaffold to mimic the extra cellular matrix for cell attachment and nutrient transportation. The nanofiber itself can also be functionalized through encapsulation or attachment of bioactive species such as extracellular matrix proteins, enzymes, and growth factors. In addition, the nanofibers can be further assembled into a variety of arrays or architectures by manipulating their alignment, stacking, or folding. All these attributes make electrospinning a powerful tool for generating nanostructured materials for a range of biomedical applications that include controlled release, drug delivery, and tissue engineering. This talk will focus on the use of electrospun nanofibers as scaffolds for neural and bone tissue engineering.

  9. Fabrication of carbon nanowires by pyrolysis of aqueous solution of sugar within asbestos nanofibers

    Science.gov (United States)

    Butko, V. Yu.; Fokin, A. V.; Nevedomskii, V. N.; Kumzerov, Yu. A.

    2015-05-01

    Carbon nanowires have been fabricated by pyrolysis of an aqueous solution of sugar in nanochannels of asbestos fibers. Electron microscopy demonstrates that the diameter of these nanochannels corresponds to the diameter of the thinnest of the carbon nanowires obtained. Some of these nanowires have a graphite crystal lattice and internal pores. After asbestos is etched out, the carbon nanowires can retain the original shape of the asbestos fibers. Heating in an inert atmosphere reduces the electrical resistivity of the carbon nanowires to ˜0.035 Ω cm.

  10. Clothing polymer fibers with well-aligned and high-aspect ratio carbon nanotubes

    Science.gov (United States)

    Sun, Gengzhi; Zheng, Lianxi; An, Jia; Pan, Yongzheng; Zhou, Jinyuan; Zhan, Zhaoyao; Pang, John H. L.; Chua, Chee Kai; Leong, Kah Fai; Li, Lin

    2013-03-01

    It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties.It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34208e

  11. Anchoring Fe3O4 nanoparticles on three-dimensional carbon nanofibers toward flexible high-performance anodes for lithium-ion batteries

    Science.gov (United States)

    Wan, Yizao; Yang, Zhiwei; Xiong, Guangyao; Guo, Ruisong; Liu, Ze; Luo, Honglin

    2015-10-01

    There is growing interest in flexible, cost-effective, and binder-free energy storage devices to meet the special needs of modern electronic systems. Herein we report a general, scalable, eco-friendly, and cost-effective approach for the fabrication of nano-Fe3O4-anchored three-dimensional (3D) carbon nanofiber (CNFs) aerogels (Fe3O4@BC-CNFs). The preparation processes include the anchoring of Fe2O3 nanoparticles on bacterial cellulose (BC) nanofibers with intrinsic 3D network structure and subsequent carbonization at different temperatures. The aerogel carbonized at 600 °C (Fe3O4@BC-CNFs-600) is highly flexible and was directly used as working electrodes in lithium-ion batteries without metal current collectors, conducting additives, or binders. The Fe3O4@BC-CNFs-600 demonstrates greatly improved electrochemical performance in comparison to the bare Fe3O4 nanoparticles. In addition to its excellent flexibility, a stable capacity of 755 mAh g-1 for up to 80 cycles is also higher than most of carbon-Fe3O4 hybrids. The high reversible capacity and excellent rate capability are attributed to its 3D porous network structure with well-dispersed Fe3O4 nanoparticles on the surfaces of CNFs.

  12. Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays.

    Science.gov (United States)

    Stano, Kelly L; Carroll, Murphy; Padbury, Richard; McCord, Marian; Jur, Jesse S; Bradford, Philip D

    2014-11-12

    Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.

  13. Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures

    Science.gov (United States)

    Kaul, Anupama B.; Megerian, Krikor G.; Von Allmen, Paul A.; Baron, Richard L.

    2010-01-01

    Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are

  14. Nanofibre-assisted alignment of carbon nanotubes in macroscopic polymer matrix via a scaffold-based method

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available A facile way for alignment of carbon nanotubes in macroscopic polymer matrix was developed by combining electrospinning and in-situ polymerization. The approach is based on the formation of nanofibre scaffolds with wellaligned arrays, which is filled with carbon nanotubes (CNTs. CNTs will be well aligned in macroscopic polymer matrix when the aligned nanofibre scaffold containing CNTs has been incorporated into the poly(methyl methacrylate (PMMA matrix by in-situ polymerization. We demonstrate that this scaffold approach is broadly applicable and allows for the fabrication of nanocomposites with accurately aligned nanofillers. The results presented in this report show that the approach is ideal by using polyacrylonitrile (PAN nanofibres as a scaffold of multiwalled carbon nanotubes (MWNTs, and PMMA as the macroscopic polymer matrix. The tensile strength (7.2 wt% MWNTs/PAN nanofibres loadings reaches 48.61 MPa, 87% higher than that pure PMMA, and the tensile modulus is increased by 175%.

  15. Controllable preparation of multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets on electrospun carbon nanofibers for high-performance supercapacitors

    International Nuclear Information System (INIS)

    Graphical Abstract: Multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets grown on electrospun carbon nanofiber membranes were prepared via electrospinning combined with solution co-deposition for high-performance supercapacitor electrodes. - Highlights: • Ni-Co LDH@CNFhybridswerepreparedbyelectrospinningandsolutionco-deposition. • Ni-Co LDH@CNF hybrids show high electrochemical performance for supercapacitors. • This method can be extended to other bimetallic@CNF hybrids for electrode materials. - Abstract: Hybrid nanomaterials with hierarchical structures have been considered as one kind of the most promising electrode materials for high-performance supercapacitors with high capacity and long cycle lifetime. In this work, multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanorods/nanosheets on carbon nanofibers (CNFs) were prepared by electrospinning technique combined with one-step solution co-deposition method. Carbon nanofiber membranes were obtained by electrospinning of polyacrylonitrile (PAN) followed by pre-oxidation and carbonization. The successful growth of Ni-Co LDH with different morphologies on CNF membrane by using two kinds of auxiliary agents reveals the simplicity and universality of this method. The uniform and immense growth of Ni-Co LDH on CNFs significantly improves its dispersion and distribution. Meanwhile the hierarchical structure of carbon nanofiber@nickel-cobalt layered double hydroxide nanorods/nanosheets (CNF@Ni-Co LDH NR/NS) hybrid membranes provide not only more active sites for electrochemical reaction but also more efficient pathways for electron transport. Galvanostatic charge-discharge measurements reveal high specific capacitances of 1378.2 F g−1 and 1195.4 F g−1 (based on Ni-Co LDH mass) at 1 A g−1 for CNF@Ni-Co LDH NR and CNF@Ni-Co LDH NS hybrid membranes, respectively. Moreover, cycling stabilities for both hybrid membranes are

  16. High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate.

    Science.gov (United States)

    Guzmán de Villoria, R; Figueredo, S L; Hart, A J; Steiner, S A; Slocum, A H; Wardle, B L

    2009-10-01

    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/Al2O3 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 approximately 1 mm are achieved at substrate speeds up to 2.4 mm s(-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. PMID:19752503

  17. Growth of Aligned Carbon Nanotubes on Large Scale by Methane Decomposition with Deactivation Inhibitor

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Zhili Li; Cheng Zhang; Feng Peng; Hongjuan Wang

    2007-01-01

    The effects of additives containing iron or nickel during chemical vapor deposition (CVD) on the growth of carbon nanotubes (CNTs) by methane decomposition on Mo/MgO catalyst were investigated. Ferrocene and nickel nitrate were introduced as deactivation inhibitors by in-situ evaporation during CVD. The precisely controlled in-situ introduction of these inhibitors increased the surface renewal of catalyst, and therefore prevented the catalyst from deactivation. Using this method, aligned multi-walled CNTs with parallel mesopores can be produced on a large scale.

  18. Modeling and experimental study of resistive switching in vertically aligned carbon nanotubes

    Science.gov (United States)

    Ageev, O. A.; Blinov, Yu F.; Ilina, M. V.; Ilin, O. I.; Smirnov, V. A.

    2016-08-01

    Model of the resistive switching in vertically aligned carbon nanotube (VA CNT) taking into account the processes of deformation, polarization and piezoelectric charge accumulation have been developed. Origin of hysteresis in VA CNT-based structure is described. Based on modeling results the VACNTs-based structure has been created. The ration resistance of high-resistance to low-resistance states of the VACNTs-based structure amounts 48. The correlation the modeling results with experimental studies is shown. The results can be used in the development nanoelectronics devices based on VA CNTs, including the nonvolatile resistive random-access memory.

  19. Flow Field Induced Steady Alignment of Oxidized Multi-walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ai Zhong XU; Ming Shu YANG; Qiang WU; Xiao Ming HU; Lei JIANG

    2005-01-01

    The steady ordered micro-ribbons of oxidized multi-walled carbon nanotubes (MWNTs)were obtained through micro-aperture PTFE membrane by vacuum filtration. After treatment by mixture of concentrated nitric acid and sulfuric acid, the surface functional groups modified MWNTs can be easily dispersed to form a homogeneous suspension. It is found that the steady micro-ribbons existed in the films obtained by vacuum filtration of the suspension. The filtration formed steady flow field and induced steady alignment of oxidized MWNTs. The chemical treatment of MWNTs forming strong interaction between MWNTs is necessity to keep steady of the micro-ribbons microstructure.

  20. 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)