WorldWideScience

Sample records for carbon nanofibers cnfs

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

    OpenAIRE

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

    2014-01-01

    The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac)/Nafion/gla...

  2. Effect of carbon nanofibers content on thermal properties of ceramic nanocomposites

    OpenAIRE

    Borrell Toma?s, Mari?a Amparo; Rocha, Victoria G.; Torrecillas San Milla?n, Ramo?n; Ferna?ndez Valde?s, Adolfo

    2011-01-01

    The thermal properties of carbon nanofibers (CNFs)-alumina and CNFs-zirconia nanocomposites densified by spark plasma sintering technique were evaluated. The influence of CNFs content and type of ceramic matrix on thermal conductivity of ceramic-CNFs materials, measured by the laser-flash method, was studied. The effect of CNFs depends noticeably on the ceramic component and thus, an increase of 83% and a decrease of 97% in thermal conductivity at room temperature is observed when 80 vol% of ...

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

  4. 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 ?A/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 ?M 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.

  5. Laccase biosensor based on electrospun copper/carbon composite nanofibers for catechol detection.

    Science.gov (United States)

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

    2014-01-01

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

  6. Bottom-up sample preparation technique for interfacial characterization of vertically aligned carbon nanofibers

    International Nuclear Information System (INIS)

    We propose a novel technique for characterizing interfacial structures in vertically aligned carbon nanofibers (CNFs) utilizing scanning transmission electron microscopy (STEM). In this technique, vertically aligned CNFs are selectively grown using plasma-enhanced chemical vapor deposition (PECVD), on a substrate comprising a narrow strip (width ?100 nm) formed by focused ion beam. Using STEM, we obtain images of nanostructures of CNFs having diameters as small as 10 nm, while focusing on the interfacial region near the nanofiber base. Stacked graphite sheets parallel to the substrate are observed near the base of these CNFs

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

    OpenAIRE

    Tribolet, Pascal; Kiwi-minsker, Lioubov

    2005-01-01

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

  8. Effect of CNFs content on the tribological behaviour of spark plasma sintering ceramic-CNFs composites

    OpenAIRE

    Borrell Toma?s, Mari?a Amparo; Torrecillas San Milla?n, Ramo?n; Rocha, Victoria G.; Ferna?ndez Valde?s, Adolfo; Bonache, V.; Salvador, M. D.

    2012-01-01

    Alumina-carbon nanofibres (CNFs) and silicon carbide-CNFs nanocomposites with different volume fraction of CNFs (0-100vol.%) were obtained by spark plasma sintering. The effect of CNFs content on the tribological behaviour in dry sliding conditions on the ceramic-carbon nanocomposites has been investigated using the ball-on-disk technique against alumina balls. The wear rate of ceramic-CNFs nanocomposites decreases with CNFs increasing content. The friction coefficient of the Al 2O 3/CNFs and...

  9. Fabrication of Uniform Au–Carbon Nanofiber by Two-Step Low Temperature Decomposition

    OpenAIRE

    Lee, Myeongsoon; Hong, Seong-cheol; Kim, Don

    2009-01-01

    This paper presents a facile and efficient way to prepare carbon nanofibers ornamented with Au nanoparticles (Au/CNFs). Gold nanoparticles were first deposited in the channels of an anodized aluminum oxide (AAO) membrane by thermal decomposition of HAuCl4and then carbon nanofibers were produced in the same channels loaded with the Au nanoparticles by decomposition of sucrose at 230 °C. An electron microscopy study revealed that the carbon nanofibers, ~10 nm thick and 6 ?m long, were decorat...

  10. Functionalized carbon nanofibers as solid-acid catalysts for transesterification.

    Science.gov (United States)

    Stellwagen, Daniel R; van der Klis, Frits; van Es, Daan S; de Jong, Krijn P; Bitter, Johannes H

    2013-09-01

    Carbon nanofibers (CNFs) were functionalized with aryl sulfonic acid groups using in situ diazonium coupling. The use of diazonium coupling yielded an acidic carbon material, in which the introduced acidic groups are readily accessible to the triglyceride substrate. The material is an efficient catalyst for the transesterification of triolein and methanol, outperforming conventional sulfonated carbons in both stability and activity per acid site. Upon comparing CNFs with varying degrees of functionalization, a linear correlation between sulfonic acid sites and catalytic performance was found. PMID:23908100

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

    Science.gov (United States)

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

    2015-03-01

    The purpose of this work was to investigate the performance of electrodes synthesized with Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs). The homogenous PAN solutions with different concentrations were prepared and electrospun to acquire PAN nanofibers and then CNFs were fabricated by heat treatment. The effective parameters for the production of electrospun CNF electrode were investigated. Scanning electron microscopy (SEM) was used to characterize electrospun nanofibers. Cyclic voltammetry was applied to investigate the changes of behavior of electrospun CNF electrodes with different diameters. The structure of CNFs was also evaluated via X-ray diffraction (XRD) and Raman spectroscopy. The results exhibited that diameter of nanofibers reduced with decreasing polymer concentration and applied voltage and increasing tip-to-collector distance, while feeding rate did not have significant effect on nanofiber diameter. The investigations of electrochemical behavior also demonstrated that cyclic voltammetric response improved as diameter of CNFs electrode decreased. PMID:25579970

  12. Pulsed laser dewetting of nickel catalyst for carbon nanofiber growth

    International Nuclear Information System (INIS)

    We present a pulsed laser dewetting technique that produces single nickel catalyst particles from lithographically patterned disks for subsequent carbon nanofiber growth through plasma enhanced chemical vapor deposition. Unlike the case for standard heat treated Ni catalyst disks, for which multiple nickel particles and consequently multiple carbon nanofibers (CNFs) are observed, single vertically aligned CNFs could be obtained from the laser dewetted catalyst. Different laser dewetting parameters were tested in this study, such as the laser energy density and the laser processing time measured by the total number of laser pulses. Various nickel disk radii and thicknesses were attempted and the resultant number of carbon nanofibers was found to be a function of the initial disk dimension and the number of laser pulses

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

    Science.gov (United States)

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

    2014-03-01

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

  14. Control of carbon nanostructure: From nanofiber toward nanotube and back

    International Nuclear Information System (INIS)

    The unique properties of carbon nanofibers (CNFs) make them attractive for numerous applications ranging from field emitters to biological probes. In particular, it is the deterministic synthesis of CNFs, which requires precise control over geometrical characteristics such as location, length, diameter, and alignment, that enables the diverse applications. Catalytic plasma enhanced chemical vapor deposition of vertically aligned CNFs is a growth method that offers substantial control over the nanofiber geometry. However, deterministic synthesis also implies control over the nanofiber's physical and chemical properties that are defined by internal structure. Until now, true deterministic synthesis has remained elusive due to the lack of control over internal graphitic structure. Here we demonstrate that the internal structure of CNFs can be influenced by catalyst preparation and ultimately defined by growth conditions. We have found that when the growth rate is increased by 100-fold, obtained through maximized pressure, plasma power, and temperature, the resulting nanofibers have an internal structure approaching that of multiwalled nanotubes. We further show that the deliberate modulation of growth parameters results in modulation of CNF internal structure, and this property has been used to control the CNF surface along its length for site specific chemistry and electrochemistry

  15. 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.

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

    OpenAIRE

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

    2014-01-01

    Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission elect...

  17. 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.

  18. In?S?/carbon nanofibers/Au ternary synergetic system: hierarchical assembly and enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Zhang, Xin; Shao, Changlu; Li, Xinghua; Lu, Na; Wang, Kexin; Miao, Fujun; Liu, Yichun

    2015-02-11

    In this paper, carbon nanofibers (CNFs) were successfully synthesized by electrospinning technique. Next, Au nanoparticles (NPs) were assembled on the electrospun CNFs through in situ reduction method. By using the obtained Au NPs modified CNFs (CNFs/Au) as hard template, the In2S3/CNFs/Au composites were synthesized through hydrothermal technique. The results showed that the super long one-dimensional (1D) CNFs (about 306 nm in average diameter) were well connected to form a nanofibrous network; and, the Au NPs with 18 nm in average diameter and In2S3 nanosheets with 5-10nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In2S3/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In2S3 and In2S3/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron-hole pairs based on the positive synergetic effect between In2S3, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In2S3/CNFs/Au composites with hierarchical structure possess a strong adsorption ability towards organic dyes, which also contributed to the enhancement of photocatalytic activity. Moreover, the In2S3/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure. PMID:25464301

  19. One-step catalytic growth of carbon nanofiber arrays vertically aligned on carbon substrate

    International Nuclear Information System (INIS)

    Highlights: ? Acetylene as carbon resource and copper foil as catalyst. ? Three carbon nanostructures are synthesized by modulating feeding gas compositions. ? NH3 is a key factor in the growth of VA-CNF arrays. -- Abstract: Vertically aligned carbon nanofiber (VA-CNF) arrays on carbon substrate have been synthesized via one-step chemical vapor deposition process on copper foil, by using acetylene as carbon resource. Three types of carbon nanostructures, viz. bare carbon films, CNFs and VA-CNFs grown on carbon substrate, could be selectively synthesized by only modulating the concentration of C2H2 and NH3 in the feeding gases. It was found that NH3 was a key factor in the growth of VA-CNF arrays, which could increase the diffusion capability of copper atoms in carbon materials, therefore promote forming larger spherical Cu NPs catalysts for the growth of VA-CNFs. Furthermore, a growth mechanism in different feeding gas compositions was proposed.

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

    Science.gov (United States)

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

    2011-07-01

    In this work, carbon nanofibers (CNFs) were synthesized on carbon fiber (CF) surfaces precoated with metal-doped mesoporous silica films. Fe, Ni, and Co were doped in the mesoporous silica films and played the role of catalysts for the decomposition of acetylene to grow CNFs on the CF surfaces. The chemical composition and surface structure of CFs before and after the growth of the CNFs were investigated by EDX, N2 full isotherms, and SEM. The electrical property of the CFs was investigated using a four-probe volume resistivity tester. The SEM results indicated that the CNFs with diameters of 20-100 nm grew uniformly and densely on the CF surfaces. The diameter and length distributions of the CNFs were found to be dependent on the metal that was doped in the mesoporous silica films. The electrical properties of the CFs were enhanced after the CNFs' growth on the CF surfaces, and the CNFs grown over the Ni catalyst with the narrowest diameter distribution gave the lowest volume resistivity to the CFs. PMID:22121683

  1. 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 ? 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. PMID:25702869

  2. Acetylene decomposition to helical carbon nanofibers over supported copper catalysts

    International Nuclear Information System (INIS)

    The helical carbon nanofibers (CNFs), synthesized at relatively low temperatures (lower than 250 deg. C) by using Cu as a catalyst, SiO2, TiO2, Al2O3, MgO as supports and acetylene as gas source, has been investigated. The products were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The morphologies of obtained products influenced by the types of supports and weight ratios (Cu/support = 1:1, 1:5, and 1:10) were discussed. The average diameter of the helical CNFs was about 80 nm, and these CNFs had the same coil pitch, and coil diameter

  3. Electrical properties of carbon nanofiber reinforced multiscale polymer composites

    International Nuclear Information System (INIS)

    Carbon nanofiber (CNF) reinforced epoxy matrix nanocomposites and CNF reinforced glass hollow particle filled syntactic foams are studied for electrical properties. The effect of CNF weight fraction, hollow particle volume fraction, and hollow particle wall thickness on impedance and dielectric constant are characterized. The results show that the impedance decreases and the dielectric constant increases with increasing CNF content in the composites. Nanocomposites containing 10 wt.% CNFs showed significantly higher dielectric constant because of the presence of a continuous network of CNFs in the composite. CNF reinforced syntactic foams showed higher dielectric constant than the neat resin. The CNF content had a more prominent effect on the dielectric constant than the glass hollow particle volume fraction and wall thickness. The Maxwell–Garnett and the Jayasundere–Smith models are modified to include the effect of hollow particle wall thickness and obtain predictions of dielectric constants of syntactic foams. The semi-empirical predictions obtained from Maxwell–Garnett models are closer to the experimental values. Lightweight syntactic foams, tailored for electrical properties, can be useful in electronic packaging applications. - Highlights: • Using carbon nanofibers (CNFs) and glass hollow particles in multiphase composites. • The dielectric constant (?) of composites increases with CNF content. • Interconnected network of CNFs at high volume fraction exponentially increases ?. • Two theoretical models accurately predicted data trends of CNF/syntactic foams

  4. Structure, mechanical properties and friction behavior of UHMWPE/HDPE/carbon nanofibers

    International Nuclear Information System (INIS)

    Effects of untreated and pretreated carbon nanofibers (CNFs) on the crystallization behavior, friction behavior, and mechanical properties of ultra high molecular weight polyethylene (UHMWPE)/high density polyethylene (HDPE) nanocomposites prepared by a twin-screw extrusion were studied. The differential scanning calorimetry and wide angle X-ray diffraction measurements indicated that the addition of CNFs impacted the temperature of crystallization, but had no significant effects on the crystalline structure of the UHMWPE/HDPE blend. The degree of crystallinity, and the tensile strength and modulus of the UHMWPE/HDPE systems exhibited an increasing trend initially with addition of CNFs, followed by a decrease at higher contents. With the increase of untreated CNF content, the friction coefficient of UHMWPE/HDPE was decreasing and displayed less change in the process of friction. The microstructure features on the fracture surfaces and friction surfaces of the polymer blend and the nanocomposites were analyzed in detail by scanning electron microscope observations. The degree of crystallinity of the nanocomposites with the pretreated CNFs exhibited a decrease due to the better interface adhesion compared to that in the nanocomposites with the same loading untreated CNFs. The enhancement in tensile strength of nanocomposites containing 0.5 wt% treated CNFs was four times higher (32%) than that of the nanocomposites containing untreated CNFs (8%) over that of the pure potreated CNFs (8%) over that of the pure polymer

  5. Preparation of a New Adsorbent from Activated Carbon and Carbon Nanofiber (AC/CNF) for Manufacturing Organic-Vacbpour Respirator Cartridge

    OpenAIRE

    Mehdi Jahangiri; Javad Adl; Seyyed Jamaleddin Shahtaheri; Alimorad Rashidi; Amir Ghorbanali; Hossein Kakooe; Abbas Rahimi Forushani; Mohammad Reza Ganjali

    2013-01-01

    Abstract In this study a composite of activated carbon and carbon nanofiber (AC/CNF) was prepared to improve the performance of activated carbon (AC) for adsorption of volatile organic compounds (VOCs) and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF) were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were a...

  6. 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)

  7. Structural transformation and field emission enhancement of carbon nanofibers by energetic argon plasma post-treatment

    International Nuclear Information System (INIS)

    Vertically aligned carbon nanofibers (CNFs) grown by plasma enhanced chemical vapor deposition (PECVD) were transformed into cone-shaped nanostructures after treatment by argon (Ar) plasma. Significant enhancement of field emission characteristics of the post-treated CNFs has been achieved. Analysis by electron microscopy and energy dispersive spectroscopy (EDS) suggests that the structural transformation is a result of a cosputtering/deposition process by energetic plasma ions. The enhancements can be attributed to the combining effects of an additional Si/C layer coverage, catalytic nanoparticles removal and the sharpening of CNFs tips. The argon plasma post-treatment processes developed here can be easily extended to in situ PECVD processes for fabricating CNFs based emitters

  8. A laser ultrasound transducer using carbon nanofibers-polydimethylsiloxane composite thin film

    Science.gov (United States)

    Hsieh, Bao-Yu; Kim, Jinwook; Zhu, Jiadeng; Li, Sibo; Zhang, Xiangwu; Jiang, Xiaoning

    2015-01-01

    The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers-polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 ?m and 57.9 ± 2.80 ?m, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10-3 Pa/(W/m2), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

  9. Structure, mechanical properties and friction behavior of UHMWPE/HDPE/carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Sui, G. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer, Beijing University of Chemical Technology, Beijing 100029 (China); Zhong, W.H. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States)], E-mail: katie_zhong@wsu.edu; Ren, X.; Wang, X.Q. [School of Material Science and Engineering, Beihang University, Beijing 100083 (China); Yang, X.P. [Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer, Beijing University of Chemical Technology, Beijing 100029 (China)

    2009-05-15

    Effects of untreated and pretreated carbon nanofibers (CNFs) on the crystallization behavior, friction behavior, and mechanical properties of ultra high molecular weight polyethylene (UHMWPE)/high density polyethylene (HDPE) nanocomposites prepared by a twin-screw extrusion were studied. The differential scanning calorimetry and wide angle X-ray diffraction measurements indicated that the addition of CNFs impacted the temperature of crystallization, but had no significant effects on the crystalline structure of the UHMWPE/HDPE blend. The degree of crystallinity, and the tensile strength and modulus of the UHMWPE/HDPE systems exhibited an increasing trend initially with addition of CNFs, followed by a decrease at higher contents. With the increase of untreated CNF content, the friction coefficient of UHMWPE/HDPE was decreasing and displayed less change in the process of friction. The microstructure features on the fracture surfaces and friction surfaces of the polymer blend and the nanocomposites were analyzed in detail by scanning electron microscope observations. The degree of crystallinity of the nanocomposites with the pretreated CNFs exhibited a decrease due to the better interface adhesion compared to that in the nanocomposites with the same loading untreated CNFs. The enhancement in tensile strength of nanocomposites containing 0.5 wt% treated CNFs was four times higher (32%) than that of the nanocomposites containing untreated CNFs (8%) over that of the pure polymer.

  10. Carbon nanofiber interconnect RF characteristics improvement with deposited tungsten contacts.

    Science.gov (United States)

    Vyas, Anshul A; Madriz, Francisco; Kanzaki, Nobuhiko; Wilhite, Patrick; Sun, Xuhui; Yamada, Toshishige; Yang, Cary Y

    2014-03-01

    Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are potential materials for high-performance electronic devices and circuits due to their light weight and excellent electrical properties such as high current capacity and tolerance to electromigration. In addition, at high frequencies, these materials exhibit transport behavior which holds special promise for applications as on-chip interconnects. Contact resistance at CNF-metal interface is a major factor in limiting the electrical performance of CNF interconnects at all frequencies. In this paper, it is demonstrated that the contact resistance can be minimized and the high-frequency characteristics much enhanced by depositing tungsten on CNF-metal electrode contacts. PMID:24745286

  11. Growth of carbon nanofibers on carbon fabric with Ni nanocatalyst prepared using pulse electrodeposition

    International Nuclear Information System (INIS)

    The pulse electrodeposition (PED) technique was utilized to deposit nanosized (?10 nm) Ni catalysts on carbon fabric (CF). Via an in situ potential profile, the PED technique can control the Ni catalyst loading, which is an important parameter for the growth of carbon nanofibers (CNFs) on CF. The preparation of CNF-coated CF (carpet-like CF) was carried out in a thermal chemical vapor deposition system with an optimum loading of Ni catalysts deposited in the PED pulse range from 20 to 320 cycles. CNFs grown at 813 K using different pulse cycles had a narrow diameter distribution, around 15 ± 5 nm to 29 ± 7 nm; they have a hydrophobic surface, like lotus leaves. Transmission electron microscopy images confirmed the graphene structural transformation of CNFs with the growth temperature. Solid wire CNFs were initially grown at 813 K with graphene edges exposed on the external surface. At elevated growth temperatures (1073 and 1173 K), bamboo-like CNFs were obtained, with herringbone structures and intersectional hollow cores

  12. Change in carbon nanofiber resistance from ambient to vacuum

    Directory of Open Access Journals (Sweden)

    Shusaku Maeda

    2011-06-01

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

  13. Novel phenolic biosensor based on a magnetic polydopamine-laccase-nickel nanoparticle loaded carbon nanofiber composite.

    Science.gov (United States)

    Li, Dawei; Luo, Lei; Pang, Zengyuan; Ding, Lei; Wang, Qingqing; Ke, Huizhen; Huang, Fenglin; Wei, Qufu

    2014-04-01

    A novel phenolic biosensor was prepared on the basis of a composite of polydopamine (PDA)-laccase (Lac)-nickel nanoparticle loaded carbon nanofibers (NiCNFs). First, NiCNFs were fabricated by a combination of electrospinning and a high temperature carbonization technique. Subsequently, the magnetic composite was obtained through one-pot Lac-catalyzed oxidation of dopamine (DA) in an aqueous suspension containing Lac, NiCNFs, and DA. Finally, a magnetic glass carbon electrode (MGCE) was employed to separate and immobilize the composite; the modified electrode was then denoted as PDA-Lac-NiCNFs/MGCE. Fourier transform infrared (FT-IR) spectra and cyclic voltammetry (CV) analyses revealed the NiCNFs had good biocompatibility for Lac immobilization and greatly facilitated the direct electron transfer between Lac and electrode surface. The immobilized Lac showed a pair of stable and well-defined redox peaks, and the electrochemical behavior of Lac was a surface-controlled process in pH 5.5 acetate buffer solution. The PDA-Lac-NiCNFs/MGCE for biosensing of catechol exhibited a sensitivity of 25 ?A mM(-1) cm(-2), a detection limit of 0.69 ?M (S/N = 3), and a linear range from 1 ?M to 9.1 mM, as well as good selectivity and stability. Meanwhile, this novel biosensor demonstrated its promising application in detecting catechol in real water samples. PMID:24606719

  14. Growth of carbon nanofibers using resol-type phenolic resin and cobalt(II) catalyst.

    Science.gov (United States)

    Kim, Taeyun; Mees, Karina; Park, Ho-Seon; Willert-Porada, Monika; Lee, Chang-Seop

    2013-11-01

    This study investigated carbon nanofibers (CNFs) grown on reticulated vitreous carbon (RVC) foam through catalytic deposition of ethylene. Before growing the CNFs, Co(II) on the RVC foam was expected to act as a catalyst by deposition. The preparation of the CNFs was a two-step process. The first step was preparing the RVC from polyurethane (PU) foam. Changes in weight over time were evaluated using two kinds of resol. The change in the mass and state of the sample with the change in temperature was studied during the carbonization process. The second step was to prepare the CNFs. An OH group was attached by the oxidation of the RVC foam. A change in the shape and mass of the sample was observed due to a change in nitric acid concentration and oxidation time. Then, cobalt was deposited to grow CNFs on the RVC foam. Hydrolysis helped to deposit the Co(ll) on the RVC foam. The appropriate time and temperature were investigated for the reduction process. In the last step, CNFs were prepared by the introducing ethylene gas. The resulting samples were analyzed using scanning electron microscopy, energy dispersive spectroscopy, N2-sorption, and X-ray photoelectron spectroscopy. PMID:24245253

  15. Fabrication of carbon nanofiber-reinforced aluminum matrix composites assisted by aluminum coating formed on nanofiber surface by in situ chemical vapor deposition

    Science.gov (United States)

    Ogawa, Fumio; Masuda, Chitoshi

    2015-01-01

    The van der Waals agglomeration of carbon nanofibers (CNFs) and the weight difference and poor wettability between CNFs and aluminum hinder the fabrication of dense CNF-reinforced aluminum matrix composites with superior properties. In this study, to improve this situation, CNFs were coated with aluminum by a simple and low-cost in situ chemical vapor deposition (in situ CVD). Iodine was used to accelerate the transport of aluminum atoms. The coating layer formed by the in situ CVD was characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform-infrared spectroscopy, and x-ray photoelectron spectroscopy. The results confirmed that the CNFs were successfully coated with aluminum. The composites were fabricated to investigate the effect of the aluminum coating formed on the CNFs. The dispersion of CNFs, density, Vickers micro-hardness and thermal conductivity of the composites fabricated by powder metallurgy were improved. Pressure-less infiltration experiments were conducted to fabricate composites by casting. The results demonstrated that the wettability and infiltration were dramatically improved by the aluminum coating layer on CNFs. The aluminum coating formed by the in situ CVD technique was proved to be effective for the fabrication of CNF-reinforced aluminum matrix composites.

  16. Effects of the catalyst and substrate thickness on the carbon nanotubes/nanofibers as supercapacitor electrodes

    Science.gov (United States)

    Gao, Y.; Pandey, G. P.; Turner, J.; Westgate, C.; Sammakia, B.

    2012-12-01

    The different growth conditions of carbon nanotubes (CNTs)/carbon nanofibers (CNFs) which lead to different characteristics when used as supercapacitor electrodes are reported. A layer of SiO2 was coated onto the Si substrate and then a layer of Ti was evaporated as a current collector. CNTs/CNFs were synthesized on the Ti surface via a water-assisted chemical vapor deposition method at 800 °C and at atmospheric pressure utilizing iron (Fe) nanoparticles as catalysts, ethylene (C2H4) as the precursor gas and argon (Ar) and hydrogen (H2) as the carrier gases. The effects of different thicknesses of the catalyst (5 and 10 nm) and Ti substrate layer (10, 30 and 150 nm) on the specific capacitance of the CNFs were studied and the capacitance of the CNTs/CNFs-based device was dependent on CNT/CNF morphology of the CNFs that varied for different combinations of the catalyst and Ti layer thicknesses. The characterization of CNTs/CNFs was carried out using scanning electron microscopy, electron dispersive spectroscopy, transmission electron microscopy and electron diffraction. The specific capacitance was measured using cyclic voltammetry via a three-electrode system. The highest specific capacitance (60 F g-1) was obtained in the sample grown with 5 nm of Fe catalyst onto 10 nm of Ti substrate.

  17. Encapsulation of MnO Nanocrystals in Electrospun Carbon Nanofibers as High-Performance Anode Materials for Lithium-Ion Batteries

    Science.gov (United States)

    Liu, Bin; Hu, Xianluo; Xu, Henghui; Luo, Wei; Sun, Yongming; Huang, Yunhui

    2014-01-01

    A novel and controllable approach is developed for the synthesis of MnO nanocrystals embedded in carbon nanofibers (MnO/CNFs) through an electrospinning process. The as-formed MnO/CNFs have a porous structure with diameters of 100–200?nm and lengths up to several millimeters. When used as an anode material for lithium-ion batteries, the resulting MnO/CNFs exhibit superior electrochemical performances with high specific capacity, good cyclability, and excellent rate capability. The unique porous carbon nanofibers (PCNFs) can not only improve the contact area between the electrode and the electrolyte, but also alleviate the impact of the large volume effect of MnO during the electrochemical cycling. It is expected that the present synthetic strategy can be extended to synthesize other nanostructured oxides encapsulated in carbon nanofibers for extensive energy transfer and storage applications. PMID:24598639

  18. Room-temperature growth of a carbon nanofiber on the tip of conical carbon protrusions

    International Nuclear Information System (INIS)

    Glassy carbon was Ar+-ion bombarded with a simultaneous Mo supply under ultrahigh vacuum conditions using a microprotrusion fabrication system that consists of a differentially pumped ion gun and a seed-material supply source. Conical protrusions were formed by sputtering with a seed supply, and carbon nanofibers (CNFs) grew on the tips even at room temperature. The length of CNFs reached up to ?10 ?m, and their diameter was almost uniform (50 nm) in the growth direction. The short CNFs aligned in the ion beam direction, whereas the long ones were non-aligned. The CNF growth on a glassy carbon surface was ascribed to the enhanced surface texturing and to the massive redeposition of C atoms onto cones, both of which are specific to the oblique ion bombardment: The former would lead to an increase in the number of possible nucleation sites for the CNF growth, and the C atoms arising from the latter process would migrate toward the conical tips, thus forming CNFs

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

    Science.gov (United States)

    Luo, Chengzhi; Fu, Qiang; Pan, Chunxu

    2015-01-01

    It is well-known that electric and magnetic fields can control the growth direction, morphology and microstructure of one-dimensional carbon nanomaterials (1-DCNMs), which plays a key role for its potential applications in micro-nano-electrics and devices. In this paper, we introduce a novel process for controlling growth of carbon nanofibers (CNFs) with assistance of a strong magnetic field (up to 0.5 T in the center) in a chemical vapor deposition (CVD) system. The results reveal that: 1) The CNFs get bundled when grown in the presence of a strong magnetic field and slightly get aligned parallel to the direction of the magnetic field; 2) The CNFs diameter become narrowed and homogenized with increase of the magnetic field; 3) With the increase of the magnetic field, the microstructure of CNFs is gradually changed, i.e., the strong magnetic field makes the disordered “solid-cored” CNFs transform into a kind of bamboo-liked carbon nanotubes; 4) We propose a mechanism that the reason for these variations and transformation is due to diamagnetic property of carbon atoms, so that it has direction selectivity in the precipitation process. PMID:25761381

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

    Science.gov (United States)

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

    2005-06-01

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

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

    Science.gov (United States)

    Singh, Shiv; Singh, Abhinav; Bais, Vaibhav Sushil Singh; Prakash, Balaji; Verma, Nishith

    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. PMID:24656351

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

    OpenAIRE

    George JinuJacob; Bhowmick Anil

    2008-01-01

    Abstract Carbon nanofiber (CNF) is one of the stiffest materials produced commercially, having excellent mechanical, electrical, and thermal properties. The reinforcement of rubbery matrices by CNFs was studied in the case of ethylene vinyl acetate (EVA). The tensile strength was greatly (61%) increased, even for very low fiber content (i.e., 1.0 wt.%). The surface modification of the fiber by high energy electron beam and gamma irradiation led to better dispersion in the rubber matrix. This ...

  3. Direct growth of carbon nanofibers to generate a 3D porous platform on a metal contact to enable an oxygen reduction reaction.

    Science.gov (United States)

    Pan, David; Ombaba, Matthew; Zhou, Zhi-You; Liu, Yang; Chen, Shaowei; Lu, Jennifer

    2012-12-21

    For carbon nanotube-based electronics to achieve their full performance potential, it is imperative to minimize the contact resistance between macroscale metal contacts and the carbon nanotube (CNT) nanoelectrodes. We have developed a three-dimensional electrode platform that consists of carbon nanofibers (CNFs) that are directly grown on a metal contact, such as copper (Cu). Carbon nanofiber morphology can be tailored by adjusting the annealing time of a thin electrochemically deposited nickel catalyst layer on copper. We demonstrate that increasing the annealing time increases the amount of copper infused into the nickel catalyst layer. This reduces the carbon deposition rate, and consequently a more well-defined CNF 3D architecture can be fabricated. This direct growth of CNFs on a Cu substrate yields an excellent electron transfer pathway, with contact resistance between CNFs and Cu being comparable to that of a Cu-Cu interface. Furthermore, the excellent bonding strength between CNFs and Cu can be maintained over prolonged periods of ultrasonication. The porous 3D platform affixed with intertwined CNFs allows facile surface functionalization. Using a simple solution soaking procedure, the CNF surface has been successfully functionalized with iron(II) phthalocyanine (FePc). FePc functionalized CNFs exhibit excellent oxygen reduction capability, equivalent to platinum-carbon electrodes. This result demonstrates the technological promise of this new 3D electrode platform that can be exploited in other applications that include sensing, battery, and supercapacitors. PMID:23171171

  4. Morphological evolution of carbon nanofibers encapsulating SnCo alloys and its effect on growth of the solid electrolyte interphase layer.

    Science.gov (United States)

    Shin, Jungwoo; Ryu, Won-Hee; Park, Kyu-Sung; Kim, Il-Doo

    2013-08-27

    Two distinctive one-dimensional (1-D) carbon nanofibers (CNFs) encapsulating irregularly and homogeneously segregated SnCo nanoparticles were synthesized via electrospinning of polyvinylpyrrolidone (PVP) and polyacrylonitrile (PAN) polymers containing Sn-Co acetate precursors and subsequent calcination in reducing atmosphere. CNFs synthesized with PVP, which undergoes structural degradation of the polymer during carbonization processes, exhibited irregular segregation of heterogeneous alloy particles composed of SnCo, Co3Sn2, and SnO with a size distribution of 30-100 nm. Large and exposed multiphase SnCo particles in PVP-driven amorphous CNFs (SnCo/PVP-CNFs) kept decomposing liquid electrolyte and were partly detached from CNFs during cycling, leading to a capacity fading at the earlier cycles. The closer study of solid electrolyte interphase (SEI) layers formed on the CNFs reveals that the gradual growth of fiber radius due to continuous increment of SEI layer thickness led to capacity fading. In contrast, SnCo particles in PAN-driven CNFs (SnCo/PAN-CNFs) showed dramatically reduced crystallite sizes (<10 nm) of single phase SnCo nanoparticles which were entirely embedded in dense, semicrystalline, and highly conducting 1-D carbon matrix. The growth of SEI layer was limited and saturated during cycling. As a result, SnCo/PAN-CNFs showed much improved cyclability (97.9% capacity retention) and lower SEI layer thickness (86 nm) after 100 cycles compared to SnCo/PVP-CNFs (capacity retention, 71.9%; SEI layer thickness, 593 nm). This work verifies that the thermal behavior of carbon precursor is highly responsible for the growth mechanism of SEI layer accompanied with particles detachment and cyclability of alloy particle embedded CNFs. PMID:23875909

  5. Greater cardiomyocyte density on aligned compared with random carbon nanofibers in polymer composites

    Directory of Open Access Journals (Sweden)

    Asiri AM

    2014-11-01

    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: Carbon nanofibers (CNFs randomly embedded in poly(lactic-co-glycolic-acid (PLGA composites have recently been shown to promote cardiomyocyte growth when compared with conventional PLGA without CNFs. It was shown then that PLGA:CNF composites were conductive and that conductivity increased as greater amounts of CNFs were added to pure PLGA. Moreover, tensile tests showed that addition of CNFs increased the tensile strength of the PLGA composite to mimic that of natural heart tissue. Most importantly, throughout all cytocompatibility experiments, cardiomyocytes were viable and expressed important biomarkers that were greatest on 50:50 wt% CNF:PLGA composites. The increased selective adsorption of fibronectin and vitronectin (critical proteins that mediate cardiomyocyte function onto such composites proved to be the mechanism of action. However, the natural myocardium is anisotropic in terms of mechanical and electrical properties, which was not emulated in these prior PLGA:CNF composites. Thus, the aim of this in vitro study was to create and characterize CNFs aligned in PLGA composites (at 50:50 wt%, including their mechanical and electrical properties and cardiomyocyte density, comparing such results with randomly oriented CNFs in PLGA. Specifically, CNFs were added to soluble biodegradable PLGA (50:50 PGA:PLA weight ratio and aligned by applying a voltage and then allowing the polymer to cure. CNF surface micron patterns (20 µm wide on PLGA were then fabricated through a mold method to further mimic myocardium anisotropy. The results demonstrated anisotropic mechanical and electrical properties and significantly improved cardiomyocyte density for up to 5 days on CNFs aligned in PLGA compared with being randomly oriented in PLGA. These results indicate that CNFs aligned in PLGA should be further explored for improving cardiomyocyte density, which is necessary in numerous cardiovascular applications. Keywords: cardiomyocytes, poly(lactic-co-glycolic acid, carbon nanofibers, aligned, nanotechnology, anisotropy

  6. The study of controlling pore size on electrospun carbon nanofibers for hydrogen adsorption.

    Science.gov (United States)

    Im, Ji Sun; Park, Soo-Jin; Kim, Tae Jin; Kim, Young Ho; Lee, Young-Seak

    2008-02-01

    Polyacrylonitrile (PAN)-based carbon nanofibers (CNFs) were prepared by using electrospinning method and heat treatment to get the media for hydrogen adsorption storage. Potassium hydroxide and zinc chloride activations were conducted to increase specific surface area and pore volume of CNFs. To investigate the relation between pore structure and the capacity of hydrogen adsorption, textural properties of activated CNFs were studied with micropore size distribution, specific surface area, and total pore volume by using BET (Brunauer-Emmett-Teller) surface analyzer apparatus and the capacity of hydrogen adsorption was evaluated by PCT (pressure-composition-temperature) hydrogen adsorption analyzer apparatus with volumetric method. The surface morphology of activated CNFs was observed by SEM (scanning electron microscope) images to investigate the surface change through activation. Even though specific surface area and total pore volume were important factors for increasing the capacity of hydrogen adsorption, the pore volume which has pore width (0.6-0.7 nm) was a much more effective factor than specific surface area and pore volume in PAN-based electrospun activated CNFs. PMID:17988675

  7. 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

  8. A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Koo, J; Kang, Y [Department of Mechanical Engineering Kyung Hee University, 1, Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Kleinstreuer, C [Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, 3211 Broughton Hall, Raleigh, NC 27695-7910 (United States)], E-mail: jmkoo@khu.ac.kr

    2008-09-17

    It has been experimentally demonstrated that suspensions of carbon nanotubes (CNTs) and nanofibers (CNFs) significantly increase the thermal conductivity of nanofluids; however, a physically sound theory of the underlying phenomenon is still missing. In this study, the nonlinear nature of the effective thermal conductivity enhancement with the particle concentration of CNT and CNF nanofluids is explained physically using the excluded volume concept. Specifically, the number of contacting CNTs and CNFs could be calculated by using the excluded volume concept, where the distance for heat to travel in a cylinder between the contacting cylinders in the thermal network of percolating CNTs and CNFs increased with the excluded volume. In contrast to the effective thermal conductivity model of Sastry et al (2008 Nanotechnology 19 055704) the present revised model could reproduce the nonlinear increase of the thermal conductivity with particle concentration, as well as the dependence on the diameter and aspect ratio of the CNTs and CNFs. It was found that the alignment of CNTs and CNFs due to the long range repulsion force decreases the excluded volume, leading to both the convex and concave nonlinear as well as linear increase of the thermal conductivity with particle concentration. The difference between various carrier fluids of the suspensions could be explained as the result of the change in the excluded volume in different base fluids.

  9. A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions

    International Nuclear Information System (INIS)

    It has been experimentally demonstrated that suspensions of carbon nanotubes (CNTs) and nanofibers (CNFs) significantly increase the thermal conductivity of nanofluids; however, a physically sound theory of the underlying phenomenon is still missing. In this study, the nonlinear nature of the effective thermal conductivity enhancement with the particle concentration of CNT and CNF nanofluids is explained physically using the excluded volume concept. Specifically, the number of contacting CNTs and CNFs could be calculated by using the excluded volume concept, where the distance for heat to travel in a cylinder between the contacting cylinders in the thermal network of percolating CNTs and CNFs increased with the excluded volume. In contrast to the effective thermal conductivity model of Sastry et al (2008 Nanotechnology 19 055704) the present revised model could reproduce the nonlinear increase of the thermal conductivity with particle concentration, as well as the dependence on the diameter and aspect ratio of the CNTs and CNFs. It was found that the alignment of CNTs and CNFs due to the long range repulsion force decreases the excluded volume, leading to both the convex and concave nonlinear as well as linear increase of the thermal conductivity with particle concentration. The difference between various carrier fluids of the suspensions could be explained as the result of the change in the excluded volume in different base fluidsluids

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

    Science.gov (United States)

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

    2015-02-01

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

  11. Interweaved Si@C/CNTs and CNFs composites as anode materials for Li-ion batteries

    International Nuclear Information System (INIS)

    Graphical abstract: In summary, a serious of high-energy wet ball milling, closed spray drying and subsequent chemical vapor deposition methods were introduced successfully to fabricated novel Si@C/CNTs and CNFs composites with carbon nanotubes and carbon nanofibres interweaved with carbon coated silicon spherical composites as superior anodes in lithium-ion batteries. The core-shell structure of Si@C composites can accommodate the volume change of electrode during charge and discharge. Meanwhile, the citric acid pyrolyzed carbon was coated on the surface of the silicon perfectly and constructs the connection network of nano silicon particles. Moreover, the carbon nanotubes and carbon nanofibres, which is interweaved with nano-silicon, also allows high electrical conductivity, improved solid–electrolyte interface formation and structural integrity. Compared with pure silicon and Si@C composites, the novel Si@C/CNTs and CNFs composites had the best combination of reversible capacity and cycleablity, and this anode materials exhibited excellent electrochemical performance. The Si/C composite had a fairly high initial discharge capacity of 2168.7 mA h g?1 with an efficiency of 73%, and the discharge capacity of the 50th cycle maintained surprisingly of 1194.9 mA h g?1. Meanwhile, spray drying and chemical vapor deposition are environmentally friendly, economical, and relatively high-yield method for the production of the Si@C/CNTs and CNFs composites in large quantities. Consequently, the novel Si@C/CNTs and CNFs composite electrodes may be a potential alternative to graphite for high energy density lithium ion batteries. Highlights: • The core/shell structured silicon/carbon composites were prepared by a facile way. • The as-prepared Si@C/CNTs and CNFs composites shows excellent electrochemical performance. • The preparation method has mild experiment conditions and high production rate. • The structure benefited electronic transfer and accommodated volume expansion. -- Abstract: Novel silicon@ carbon/carbon nanotubes and carbon nanofibres (Si@C/CNTs and CNFs) composites have been successfully synthesized by a serious of high-energy wet ball milling, closed spray drying and subsequently chemical vapor deposition methods, in which carbon nanotubes and carbon nanofibers are interweaved with carbon coated silicon (Si@C) spherical composites. As anode materials for lithium-ion batteries, the Si@C/CNTs and CNFs composites demonstrate a high first discharge capacity and excellent cycle ability. The high initial specific discharge capacity is approximately 2169 mA h g?1 and a reversible specific capacity approached 1195 mA h g?1 after 50 cycles at a high current density of 300 mA g?1

  12. Deposition of vertically oriented carbon nanofibers in atmospheric pressure radio frequency discharge

    International Nuclear Information System (INIS)

    Deposition of vertically oriented carbon nanofibers (CNFs) has been studied in an atmospheric pressure radio frequency discharge without dielectric barrier covering the metallic electrodes. When the frequency is sufficiently high so that ions reside in the gap for more than one rf cycle ('trapped ions'), the operating voltage decreases remarkably and the transition from a uniform glow discharge to an arc discharge is suppressed even without dielectric barriers. More importantly, the trapped ions are able to build up a cathodic ion sheath. A large potential drop is created in the sheath between the bulk plasma and the electrode, which is essential for aligning growing CNFs. At the same time, the damage to CNFs due to ion bombardment can be minimized at atmospheric pressure. The primary interest of the present work is in identifying the cathodic ion sheath and investigating how it influences the alignment of growing CNFs in atmospheric pressure plasma-enhanced chemical-vapor deposition. Spectral emission profiles of He (706 nm), H? (656 nm), and CH (432 nm) clearly showed that a dark space is formed between the cathode layer and the heated bottom electrode. However, increasing the rf power induced the transition to a nonuniform ?-mode discharge which creates intense plasma spots in the dark space. Aligned CNFs can be grown at moderate input power during the initial stage of the deposition process. Catalyst particles were heavily contaminated by precipitated carbon in contaminated by precipitated carbon in less than 5 min. Alignment deteriorates as CNFs grow and deposition was virtually terminated by the deactivation of catalyst particles

  13. Carbon nanofiber reinforced aluminum matrix composite fabricated by combined process of spark plasma sintering and hot extrusion.

    Science.gov (United States)

    Kwon, Hansang; Kurita, Hiroki; Leparoux, Marc; Kawasaki, Akira

    2011-05-01

    Spark plasma sintering and hot extrusion processes have been employed for fabricating carbon nanofiber (CNF)-aluminum (Al) matrix bulk materials. The Al powder and the CNFs were mixed in a mixing medium of natural rubber. The CNFs were well dispersed onto the Al particles. After removal of the natural rubber, the Al-CNF mixture powders were highly densified. From the microstructural viewpoint, the composite materials were observed by optical, field-emission scanning electron, and high-resolution transmission electron microscopies. The CNFs were found to be located on every grain boundary and aligned with the extrusion direction of the Al-CNF bulk materials. Some Al carbides (Al4C3) were also observed at the surface of the CNFs. This carbide was created by a reaction between the Al and the disordered CNF. The CNFs and the formation of Al4C3 play an important role in the enhancement of the mechanical properties of the Al-CNF bulk material. The CNFs can also be used for engineering reinforcement of other matrix materials such as ceramics, polymers and more complex matrices. PMID:21780415

  14. Synthesis of Carbon Nanofibers Based on Resol Type Phenol Resin and Fe(III) Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Yura; Lee, Changseop [Keimyung Univ., Daegu (Korea, Republic of); Kim, Haesik [Korea E and S Co. Ltd., Daegu (Korea, Republic of)

    2012-10-15

    The carbon nanofibers (CNFs) used in this study were synthesized with an iron catalyst and ethylene as a carbon source. A concentration of 30 wt % iron(III) acetylacetonate was dissolved in resol type phenol resin and polyurethane foam was put into the solution. The sample was calendered after being cured at 80 .deg. C in air for 24 h. Stabilization and carbonization of the resol type phenol resin and reduction of the Fe{sup 3+} were completed in a high-temperature furnace by the following steps: heating to 600 .deg. C at a rate of 10 .deg. C/min with a mixture of H{sub 2}/N{sub 2} for 4 h to reduce the Fe{sup 3+} to Fe; heating to 1000 .deg. C in N{sub 2} at a rate 10 .deg. C/min for 30 minutes for pyrolysis; synthesizing CNFs in a mixture of 20.1% ethylene and H{sub 2}/N{sub 2} at 700 .deg. C for 2 h using a CVD process. Finally, the structural characterization of the CNFs was performed by scanning electron microscopy and a synthesis analysis was carried out using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Specific surface area analysis of the CNFs was also performed by N{sub 2}-sorption.

  15. Synthesis of Carbon Nanofibers Based on Resol Type Phenol Resin and Fe(III) Catalysts

    International Nuclear Information System (INIS)

    The carbon nanofibers (CNFs) used in this study were synthesized with an iron catalyst and ethylene as a carbon source. A concentration of 30 wt % iron(III) acetylacetonate was dissolved in resol type phenol resin and polyurethane foam was put into the solution. The sample was calendered after being cured at 80 .deg. C in air for 24 h. Stabilization and carbonization of the resol type phenol resin and reduction of the Fe3+ were completed in a high-temperature furnace by the following steps: heating to 600 .deg. C at a rate of 10 .deg. C/min with a mixture of H2/N2 for 4 h to reduce the Fe3+ to Fe; heating to 1000 .deg. C in N2 at a rate 10 .deg. C/min for 30 minutes for pyrolysis; synthesizing CNFs in a mixture of 20.1% ethylene and H2/N2 at 700 .deg. C for 2 h using a CVD process. Finally, the structural characterization of the CNFs was performed by scanning electron microscopy and a synthesis analysis was carried out using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Specific surface area analysis of the CNFs was also performed by N2-sorption

  16. In situ growth cupric oxide nanoparticles on carbon nanofibers for sensitive nonenzymatic sensing of glucose

    International Nuclear Information System (INIS)

    Highlights: • CuO nanoparticles were directly and homogeneously grown on carbon nanofibers. • The obtained nanocomposite showed high electrooxidize activity to glucose. • A nonenzymatic glucose sensor was constructed based on the functional nanocomposite. • This sensor showed good performance to glucose. • The proposed sensor was successfully applied in detection of glucose in blood serum. -- Abstract: A novel method was employed to directly and homogeneously attaching cupric oxide nanoparticles (CuONPs) on carbon nanofibers (CNFs) for sensitive amperometric nonenzymatic sensing of glucose. The obtained CuONPs-CNFs nanocomposite was characterized by transmission electron microscopy and X-ray diffraction. The CuONPs-CNFs nanocomposite modified glassy carbon electrode showed high electrocatalytic activity toward the oxidation of glucose in alkaline media and a nonenzymatic glucose sensor was constructed based on the functional nanocomposite modified electrode. Under optimal experimental conditions, the designed sensor exhibited a wide linear response to glucose ranging from 5.0 × 10?7 to 1.1 × 10?2 M with a high sensitivity of 2739 ?A mM?1 cm?2 and a low detection limit down to 0.2 ?M at the signal to noise ratio of 3. This sensor showed good accuracy, acceptable precision and reproducibility. Moreover, the proposed sensor was successfully applied in the detection of glucose in human blood serum indicating its possibility in practical application

  17. Carbon-Nanofiber-Reinforced Syntactic Foams: Compressive Properties and Strain Rate Sensitivity

    Science.gov (United States)

    Poveda, Ronald L.; Gupta, Nikhil

    2014-01-01

    The current study is focused on exploring the possibility of reinforcing syntactic foams with carbon nanofibers (CNFs). Syntactic foams are hollow, particle-filled composites that are widely used in marine structures and are now finding applications in other modes of transportation due to their high stiffness-to-weight ratio. The compressive properties of syntactic foams reinforced with CNFs are characterized over the strain rate range of 10-4 to 3,000 s-1, which covers seven orders of magnitude. The results show that despite lower density with respect to neat epoxy, CNF/syntactic foams can have up to 7.3% and 15.5% higher quasi-static compressive strength and modulus, respectively, for the compositions that were characterized in the current study. In addition, these properties can be tailored over a wide range by means of hollow particle wall thickness and volume fraction, and CNF volume fraction. The compressive strength of CNF/syntactic foams is also shown to generally increase by up to a factor of 3.41 with increasing strain rate when quasi-static and high-strain-rate testing data are compared. Extensive microscopy of the CNF/syntactic foams is conducted to understand the failure and energy absorption mechanisms. Crack bridging by CNFs is observed in the specimens, which can delay final failure and increase the energy absorption capacity of the specimens. Deformation of CNFs is also noticed in the material microstructure. The deformation and failure mechanisms of nanofibers are related to the test strain rate and the structure of CNFs.

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

    Science.gov (United States)

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

    2014-01-01

    Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings. PMID:25177215

  19. 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.

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

    Science.gov (United States)

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

    2005-01-01

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

  1. Electrochemical properties for high surface area and improved electrical conductivity of platinum-embedded porous carbon nanofibers

    Science.gov (United States)

    An, Geon-Hyoung; Ahn, Hyo-Jin; Hong, Woong-Ki

    2015-01-01

    Four different types of carbon nanofibers (CNFs) for electrical double-layer capacitors (EDLCs), porous and non-porous CNFs with and without Pt metal nanoparticles, are synthesized by an electrospinning method and their performance in electrical double-layer capacitors (EDLCs) is characterized. In particular, the Pt-embedded porous CNFs (PCNFs) exhibit a high specific surface area of 670 m2 g-1, a large mesopore volume of 55.7%, and a low electrical resistance of 1.7 × 103. The synergistic effects of the high specific surface area with a large mesopore volume, and superior electrical conductivity result in an excellent specific capacitance of 130.2 F g-1, a good high-rate performance, superior cycling durability, and high energy density of 16.9-15.4 W h kg-1 for the performance of EDLCs.

  2. 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

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

    Directory of Open Access Journals (Sweden)

    George JinuJacob

    2008-01-01

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

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

    International Nuclear Information System (INIS)

    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?5x109 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 ?m.

  5. Side electron emission device using a composite of carbon nanofibers and aluminum

    International Nuclear Information System (INIS)

    A new side electron emission device (SEED) was fabricated with carbon nanofiber/aluminum (CNF/Al) composites prepared by the elastomer precursor method. In the SEED, a cross-sectional side face of the CNF/Al composite plate was perpendicularly placed onto an anode surface by inserting an insulating spacer. Above a certain threshold voltage in a vacuum, field electrons were obtained from the side face of the composite emitter. With increasing content of CNFs in the composite, the threshold voltage decreased and emission currents increased. The current of ? 8 ?A was kept stable up to 93 h under a continuous application of 1 kV. This improved stability as compared to a conventional field emission device was attributed to a reduced damage of CNFs in the SEED structure.

  6. WAXS investigations on Polyethylene -- Carbon Nanofibers Composites

    Science.gov (United States)

    Jones, Brian; Li, Jianhua; Benitez, Rogelio; Lozano, Karen; Chipara, Mircea; Cristian Chipara, Alin; Dorina Chipara, Magdalena; Sellmyer, David J.

    2008-03-01

    Nanocomposites have been obtained by high-shear mixing of isotactic polyethylene with various amounts of purified nanofiller (vapor grown carbon nanofibers type PR-24AG from Pyrograf Products, Inc) by utilizing a HAAKE Rheomix at 65 rpm and 180 ^oC for 9 min followed by an additional mixing at 90 rpm for 5 min. Composites loaded with various amounts of vapor grown carbon nanofibers have been prepared. Various spectroscopic techniques have been used to assess the interactions between the polymeric matrix and carbon nanofibers. Wide angle X - Ray scattering investigations focused on the effect of carbon nanofibers on the crystalline phases of polypropylene and on the overall crystallinity degree of the polymeric matrix. This research aims at a better understanding of the nature and structure of the polymer -- carbon nanofibers interface.

  7. In situ transmission electron microscopy study of electrochemical sodiation and potassiation of carbon nanofibers.

    Science.gov (United States)

    Liu, Ying; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Chen, Hailong; Jungjohann, Katherine L; Xu, Yunhua; Zhu, Yujie; Bigio, David; Zhu, Ting; Wang, Chunsheng

    2014-06-11

    Carbonaceous materials have great potential for applications as anodes of alkali-metal ion batteries, such as Na-ion batteries and K-ion batteries (NIB and KIBs). We conduct an in situ study of the electrochemically driven sodiation and potassiation of individual carbon nanofibers (CNFs) by transmission electron microscopy (TEM). The CNFs are hollow and consist of a bilayer wall with an outer layer of disordered-carbon (d-C) enclosing an inner layer of crystalline-carbon (c-C). The d-C exhibits about three times volume expansion of the c-C after full sodiation or potassiation, thus suggesting a much higher storage capacity of Na or K ions in d-C than c-C. For the bilayer CNF-based electrode, a steady sodium capacity of 245 mAh/g is measured with a Coulombic efficiency approaching 98% after a few initial cycles. The in situ TEM experiments also reveal the mechanical degradation of CNFs through formation of longitudinal cracks near the c-C/d-C interface during sodiation and potassiation. Geometrical changes of the tube are explained by a chemomechanical model using the anisotropic sodiation/potassiation strains in c-C and d-C. Our results provide mechanistic insights into the electrochemical reaction, microstructure evolution and mechanical degradation of carbon-based anodes during sodiation and potassiation, shedding light onto the development of carbon-based electrodes for NIBs and KIBs. PMID:24823874

  8. Polycarboxylation of carbon nanofibers under Friedel-Crafts condition: A simple route to direct binding of carboxylic functionalities to graphitic ?-system

    Science.gov (United States)

    Wu, Jiancheng; Cai, Hualun; Xu, Kai; Fu, Zien; Liu, Xin; Chen, Mingcai; Zhang, Xiuju

    2012-11-01

    The functionalization of carbon nanofibers (CNFs) with oxalyl chloride, via Friedel-Crafts reaction in the presence of aluminum chloride, was first demonstrated as an efficient way to introduce carboxyl groups onto the nanofiber sidewalls. Octa-aminophenylsilsesquioxane (OASQ) was then covalently attached to the carboxylated nanocarbon CNF-(COOH)n through amide linkage. Taking into account the nature of the electrophilic aromatic substitution, this chemical functionalization may involve formation of conjugated carboxylic acid moiety. Structural analysis combined with electron microscopy observation of the robust octasilsesquioxane species show that carboxyl groups are uniformly distributed on the nanofibers surface.

  9. Phosphorus-doped tin oxides/carbon nanofibers webs as lithium-ion battery anodes with enhanced reversible capacity

    Science.gov (United States)

    Liu, Xiaowei; Teng, Donghua; Li, Ting; Yu, Yunhua; Shao, Xiaohong; Yang, Xiaoping

    2014-12-01

    Phosphorus-doped tin oxides/carbon nanofibers (P-SnOx/CNFs) composite materials are prepared via electrospinning of a mixed solution composed of polyacrylonitrile (PAN), N,N-dimethyl formamide (DMF), tin tetrachloride, ethylene glycol and phosphoric acid as well as subsequent thermal treatments. The P-SnOx/CNFs samples with tunable P-doping contents are directly used as anodes for lithium-ion batteries without any binders and conductors, exhibiting enhanced reversible capacities and cycling stabilities in comparison with pristine undoped SnOx/CNFs (0P-SnOx/CNFs). In a controlled experiment, the 0.25P-SnOx/CNFs anode with the atomic ratio of P:Sn = 0.25:1 shows the highest specific reversible capacity of 676 mA h g-1 at 200 mA g-1 after 100 cycles. Even at a higher current density of 2000 mA g-1, it still maintains a superior specific reversible capacity of 288 mA h g-1. The improved electrochemical performances are attributed to the P-doping effects such as inducement of a stable structural protection for tin particles, and enhancement of lithium ion diffusion coefficient and electron kinetics of electrode materials.

  10. In situ characterization of vertically oriented carbon nanofibers for three-dimensional nano-electro-mechanical device applications.

    Science.gov (United States)

    Kaul, Anupama B; Megerian, Krikor G; Jennings, Andrew T; Greer, Julia R

    2010-08-01

    We have performed mechanical and electrical characterization of individual as-grown, vertically oriented carbon nanofibers (CNFs) using in situ techniques, where such high-aspect-ratio, nanoscale structures are of interest for three-dimensional (3D) electronics, in particular 3D nano-electro-mechanical-systems (NEMS). Nanoindentation and uniaxial compression tests conducted in an in situ nanomechanical instrument, SEMentor, suggest that the CNFs undergo severe bending prior to fracture, which always occurs close to the bottom rather than at the substrate-tube interface, suggesting that the CNFs are well adhered to the substrate. This is also consistent with bending tests on individual tubes which indicated that bending angles as large as approximately 70 degrees could be accommodated elastically. In situ electrical transport measurements revealed that the CNFs grown on refractory metallic nitride buffer layers were conducting via the sidewalls, whereas those synthesized directly on Si were electrically unsuitable for low-voltage dc NEMS applications. Electrostatic actuation was also demonstrated with a nanoprobe in close proximity to a single CNF and suggests that such structures are attractive for nonvolatile memory applications. Since the magnitude of the actuation voltage is intimately dictated by the physical characteristics of the CNFs, such as diameter and length, we also addressed the ability to tune these parameters, to some extent, by adjusting the plasma-enhanced chemical vapor deposition growth parameters with this bottom-up synthesis approach. PMID:20622301

  11. In situ characterization of vertically oriented carbon nanofibers for three-dimensional nano-electro-mechanical device applications

    International Nuclear Information System (INIS)

    We have performed mechanical and electrical characterization of individual as-grown, vertically oriented carbon nanofibers (CNFs) using in situ techniques, where such high-aspect-ratio, nanoscale structures are of interest for three-dimensional (3D) electronics, in particular 3D nano-electro-mechanical-systems (NEMS). Nanoindentation and uniaxial compression tests conducted in an in situ nanomechanical instrument, SEMentor, suggest that the CNFs undergo severe bending prior to fracture, which always occurs close to the bottom rather than at the substrate-tube interface, suggesting that the CNFs are well adhered to the substrate. This is also consistent with bending tests on individual tubes which indicated that bending angles as large as ? 700 could be accommodated elastically. In situ electrical transport measurements revealed that the CNFs grown on refractory metallic nitride buffer layers were conducting via the sidewalls, whereas those synthesized directly on Si were electrically unsuitable for low-voltage dc NEMS applications. Electrostatic actuation was also demonstrated with a nanoprobe in close proximity to a single CNF and suggests that such structures are attractive for nonvolatile memory applications. Since the magnitude of the actuation voltage is intimately dictated by the physical characteristics of the CNFs, such as diameter and length, we also addressed the ability to tune these parameters, to some extent, by adjusting the plasma-enhanced xtent, by adjusting the plasma-enhanced chemical vapor deposition growth parameters with this bottom-up synthesis approach.

  12. In situ characterization of vertically oriented carbon nanofibers for three-dimensional nano-electro-mechanical device applications

    Energy Technology Data Exchange (ETDEWEB)

    Kaul, Anupama B; Megerian, Krikor G [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Jennings, Andrew T; Greer, Julia R, E-mail: anupama.b.kaul@jpl.nasa.gov [Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125 (United States)

    2010-08-06

    We have performed mechanical and electrical characterization of individual as-grown, vertically oriented carbon nanofibers (CNFs) using in situ techniques, where such high-aspect-ratio, nanoscale structures are of interest for three-dimensional (3D) electronics, in particular 3D nano-electro-mechanical-systems (NEMS). Nanoindentation and uniaxial compression tests conducted in an in situ nanomechanical instrument, SEMentor, suggest that the CNFs undergo severe bending prior to fracture, which always occurs close to the bottom rather than at the substrate-tube interface, suggesting that the CNFs are well adhered to the substrate. This is also consistent with bending tests on individual tubes which indicated that bending angles as large as {approx} 70{sup 0} could be accommodated elastically. In situ electrical transport measurements revealed that the CNFs grown on refractory metallic nitride buffer layers were conducting via the sidewalls, whereas those synthesized directly on Si were electrically unsuitable for low-voltage dc NEMS applications. Electrostatic actuation was also demonstrated with a nanoprobe in close proximity to a single CNF and suggests that such structures are attractive for nonvolatile memory applications. Since the magnitude of the actuation voltage is intimately dictated by the physical characteristics of the CNFs, such as diameter and length, we also addressed the ability to tune these parameters, to some extent, by adjusting the plasma-enhanced chemical vapor deposition growth parameters with this bottom-up synthesis approach.

  13. Graphene wrapping as a protective clamping layer anchored to carbon nanofibers encapsulating Si nanoparticles for a Li-ion battery anode

    Science.gov (United States)

    Shin, Jungwoo; Park, Kyusung; Ryu, Won-Hee; Jung, Ji-Won; Kim, Il-Doo

    2014-10-01

    Carbon nanofibers encapsulating Si nanoparticles (CNFs/SiNPs) were prepared via an electrospinning method and chemically functionalized with 3-aminopropyltriethoxysilane (APS) to be grafted onto graphene oxide (GO). As a result, the thin and flexible GO, which exhibits a negative charge in aqueous solution, fully wrapped around the APS-functionalized CNFs with a positive surface charge via electrostatic self-assembly. After the formation of chemical bonds between the epoxy groups on GO and the amine groups in APS via an epoxy ring opening reaction, the GO was chemically reduced to a reduced graphene oxide (rGO). Electrochemical and morphological characterizations showed that capacity loss by structural degradation and electrolyte decomposition on Si surface were significantly suppressed in the rGO-wrapped CNFs/SiNPs (CNFs/SiNPs@rGO). Superior capacities were consequently maintained for up to 200 cycles at a high current density (1048 mA h g-1 at 890 mA g-1) compared to CNFs/SiNPs without the rGO wrapping (304 mA h g-1 at 890 mA g-1). Moreover, the resistance of the SEI layer and charge transfer resistance were also considerably reduced by 24% and 88%, respectively. The described graphene wrapping offers a versatile way to enhance the mechanical integrity and electrochemical stability of Si composite anode materials.Carbon nanofibers encapsulating Si nanoparticles (CNFs/SiNPs) were prepared via an electrospinning method and chemically functionalized with 3-aminopropyltriethoxysilane (APS) to be grafted onto graphene oxide (GO). As a result, the thin and flexible GO, which exhibits a negative charge in aqueous solution, fully wrapped around the APS-functionalized CNFs with a positive surface charge via electrostatic self-assembly. After the formation of chemical bonds between the epoxy groups on GO and the amine groups in APS via an epoxy ring opening reaction, the GO was chemically reduced to a reduced graphene oxide (rGO). Electrochemical and morphological characterizations showed that capacity loss by structural degradation and electrolyte decomposition on Si surface were significantly suppressed in the rGO-wrapped CNFs/SiNPs (CNFs/SiNPs@rGO). Superior capacities were consequently maintained for up to 200 cycles at a high current density (1048 mA h g-1 at 890 mA g-1) compared to CNFs/SiNPs without the rGO wrapping (304 mA h g-1 at 890 mA g-1). Moreover, the resistance of the SEI layer and charge transfer resistance were also considerably reduced by 24% and 88%, respectively. The described graphene wrapping offers a versatile way to enhance the mechanical integrity and electrochemical stability of Si composite anode materials. Electronic supplementary information (ESI) available: SEM images and XRD pattern of CNFs/SiNPs; photographs of CNFs/SiNPs@rGO solutions; SEM images of CNFs/SiNPs@rGO at different graphene concentrations; SEM images of CNFs@SiNPs@rGO without APS functionalization; Electrochemical cell performance of CNFs@SiNPs@rGO with different wrapping concentrations; and electrochemical impendence spectroscopy data for CNFs@SiNPs and CNFs@SiNPs@rGO after the first discharge. See DOI: 10.1039/c4nr03173c

  14. Comparative Study of the Rheological Behavior of Multiwalled Carbon Nanotubes and Nanofiber Composites Prepared by the Dilution of a Masterbatch of Polypropylene

    OpenAIRE

    Boronat Vitoria, Teodomiro; Garci?a Sanoguera, David; Pascual, J.; Peris, F.; Sa?nchez Nacher, Lourdes

    2012-01-01

    In this investigation, the characteristics and the rheological properties of two different nanocomposite systems were investigated. These systems consisted of a dispersion of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) in a polypropylene (PP) matrix. The mixing process was carried out by melt compounding with a twin-screw corotating extruder with different reinforcement amounts (0.2-20 wt %) from concentrated masterbatches (20 wt %) of PP/CNT and PP/CNF. The results show a remarkable...

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

    Directory of Open Access Journals (Sweden)

    Lichao Feng

    2014-05-01

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

  16. Spectroscopic Investigations on Polypropylene -- Carbon Nanofibers Composites

    Science.gov (United States)

    Chipara, Mircea; Brian, Jones; Lozano, Karen; Villareal, John R.; Cristian Chipara, Alin; Hernandez, Anna; Dorina Chipara, Magdalena; Sellmyer, David J.

    2008-03-01

    Nanocomposites were obtained by high-shear mixing of isotactic polypropylene (Marlex HLN-120-01; Philips Sumika Polypropylene Company) with various amounts of vapor grown carbon nanofibers (PR-24AG; Pyrograf Products, Inc) by utilizing a HAAKE Rheomix at 65 rpm and 180 ^oC for 9 min followed by an additional mixing at 90 rpm for 5 min. Composites loaded with various amounts of vapor grown carbon nanofibers have been prepared. Wide angle X-Ray scattering investigations focus on the effect of carbon nanofibers on the crystalline phases of polypropylene and on the overall crystallinity degree of the polymeric matrix. Raman spectroscopy analysis concentrates on D and G bands. X-band electron spin resonance investigations aim at a better understanding of the purity of carbon nanofibers and of the ratio between conducting and paramagnetic.

  17. Carbon nanofibers: a versatile catalytic support

    OpenAIRE

    Nelize Maria de Almeida Coelho; Jomar Livramento Barros Furtado; Cuong Pham-Huu; Ricardo Vieira

    2008-01-01

    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 pr...

  18. Field emission from combined structures of carbon nanotubes and carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jian [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Zhang Gengmin, E-mail: zgmin@pku.edu.c [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Qin Jingfang; Zhang Wei; Xing Yingjie; Guo Dengzhu; Shen Ziyong [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China)

    2010-06-01

    A convenient and inexpensive approach to producing carbonaceous field emitters has been developed. Combined structures of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) were grown on graphitic substrates with an improved chemical vapor deposition (CVD) method. The fabrication featured a high reaction temperature and a rapid temperature rising. In each combined structure, a CNT with good crystallinity was surrounded by a cone-shaped CNF. The CNTs and the bases of the CNFs were less than 0.1 and 10 mum in diameter, respectively. These combined CNT/CNF structures, several ten microns in length, had an upward orientation from the substrate and an appropriate separation between each other, which are believed to be two favorable factors to the field emission. Electron current was readily extracted from them. Current densities of 10 muA/cm{sup 2} and 1 mA/cm{sup 2} were obtained when the average fields between the anode and the cathode were 2.3 and 3.9 V/mum, respectively.

  19. Novel hybrid carbon nanofiber/highly branched graphene nanosheet for anode materials in lithium-ion batteries.

    Science.gov (United States)

    Kim, Haejune; Huang, Xingkang; Guo, Xiaoru; Wen, Zhenhai; Cui, Shumao; Chen, Junhong

    2014-11-12

    The novel hybrid carbon nanofiber (CNF)/highly branched graphene nanosheet (HBGN) is synthesized via a simple two-step CVD method and its application as the anode material in a lithium-ion battery (LIB) is demonstrated. The CNFs offer a good electrical conductivity and a robust supporting structure, while the HBGNs provide increased Li storage sites including nanoporous cavities, large surface area, and edges of exposed graphene platelets. The hybrid material showed a reversible capacity of 300 mAh g(-1) with excellent cycling stability. Our study provides a new avenue for design and synthesis of carbon-carbon hybrid materials for versatile applications. PMID:25310206

  20. Determination of morphology and properties of carbon nanofibers and carbon nanofiber polymer nanocomposites

    Science.gov (United States)

    Lawrence, Joseph G.

    Vapor grown carbon nanofibers which resemble carbon nanotubes in structure and properties, have been extensively manufactured and investigated in recent years. Carbon nanofibers have been used for producing multifunctional materials due to their excellent properties and low cost of production. Since, commercially available vapor grown carbon nanofibers are subjected to different processing and post processing conditions, the morphology and properties of these nanofibers are not well-known. In this study, we focus on the characterization of the morphology and properties of these nanofibers and the polymer nanocomposites made using these nanofibers as reinforcements. The morphology of the nanofibers was studied employing high resolution Transmission Electron Microscopy (TEM) images. The analysis showed that the nanofibers consist primarily of conical nanofibers, but can contain a significant amount of bamboo nanofibers. Most of the conical nanofibers were found to consist of an ordered inner layer and a disordered outer layer, with the cone angle distribution of the inner layers indicating that these cannot have a stacked cone structure but are compatible with a cone-helix structure. Nanofibers that were heat treated to temperatures above 1,500°C undergo a structural transformation with the ordered inner layers changing from a cone-helix structure to a highly ordered multiwall stacked cone structure. Due to the complexity in the structure of these nanofibers, a novel method to study the elastic properties and corresponding morphology of individual nanofibers has been developed combining Atomic Force Microscopy (AFM), TEM and Focused Ion Beam (FIB) technology. Employing the developed method, the elastic modulus of individual nanofibers and their corresponding dimensions and morphology were determined. The dependence of elastic properties on the wall thickness and the orientation of graphene sheets in the nanofibers were studied. The elastic modulus of these individual nanofibers was found to depend on the thickness of the nanofiber. In an effort to study the morphology and properties of polymer nanocomposites, the dispersion of the nanofibers in the polymer matrix was studied using a Scanning Electron Microscope (SEM). A mixing approach and an in situ polymerization approach, for carbon nanofiber polyimide nanocomposites preparation were investigated using pristine, oxidized and surface functionalized nanofibers. Two different solvents, methylene chloride and dimethylacetimide (DMAc) were compared in the mixing approach. The SEM micrographs indicated that the poor dispersion of nanofibers results in aggregation and settling of nanofibers in the nanocomposite sample. The results suggest that the nanocomposite preparation method had a greater effect on the dispersion of nanofibers compared to the extent of nanofiber functionalization. In addition, a modified nanoindentation approach to measure the interface width and elastic properties at the interface of carbon nanofiber polymer nanocomposites was developed. Using the developed method the elastic property variation at narrow interface regions for two different composites made from three different nanofibers was studied. A gradual change in elastic modulus values was observed at the interface region. Based on the variation in elastic modulus values, the width of the interface region was determined.

  1. In situ formation of hollow graphitic carbon nanospheres in electrospun amorphous carbon nanofibers for high-performance Li-based batteries.

    Science.gov (United States)

    Chen, Yuming; Lu, Zhouguang; Zhou, Limin; Mai, Yiu-Wing; Huang, Haitao

    2012-11-01

    We report on in situ formation of hollow graphitic carbon nanospheres (HGCNs) in amorphous carbon nanofibers (ACNFs) by a combination of electrospinning, calcination and acid treatment. The prepared carbon nanofibers contain many HGCNs on which defects such as discontinuous graphene sheets with a large d-spacing in their wall exist and provide extra sites for Li(+) storage and serve as buffers for withstanding large volume expansion and shrinkage during the Li insertion and extraction procedure. Furthermore, some exposed HGCNs on the surface of the ACNFs as well as hollow structures are favorable for lithium ion diffusion from different orientations and sufficient contact between active material and electrolyte. In addition, the high conductivity architectures facilitate collection and transport of electrons during the cycling process. As a result, the ACNFs/HGCNs display a high reversible specific gravimetric capacity of ?750 mA h g(-1) and volumetric capacity of ?1.1 A h cm(-3) with outstanding rate capability and good cycling stability, which is superior to those of carbon nanofibers (CNFs), carbon nanotubes (CNTs), porous ACNFs, graphene nanosheets (GNSs), GNSs/CNFs, hollow carbon nanospheres and graphite. The synthesis process is simple, low-cost and environmentally friendly, providing new avenues for the rational engineering of high-energy carbon-based anode materials. PMID:23000946

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

    Science.gov (United States)

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

    2012-02-01

    Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized ?-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (-150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

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

    International Nuclear Information System (INIS)

    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 ?-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (?150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  4. 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 ?-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.

  5. Immobilization of nanofibrous A- or B-site substituted LaMnO3 perovskite-type oxides on macroscopic fiber with carbon nanofibers templates

    International Nuclear Information System (INIS)

    The immobilization of nanofibrous A- or B-site substituted LaMnO3 perovskite-type oxides on macroscopic silica fiber via a unique and facile carbon nanofibers (CNFs) template-based method was reported. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and the existence of nanofibrous materials immobilized on silica fiber.

  6. Carbon nanofibers modified with heteroatoms as metal-free catalysts for the oxidative dehydrogenation of propane.

    Science.gov (United States)

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

    2014-09-01

    Carbon nanofibres (CNFs) were modified with B and P by an ex?situ approach. In addition, CNFs doped with N were prepared in?situ using ethylenediamine as the N and C source. After calcination, the doped CNFs were used as catalysts for the oxidative dehydrogenation of propane. For B-CNFs, the effects of boron loading and calcination temperature on B speciation and catalytic conversion were studied. For the same reaction temperatures and conversions, B- and P-doped CNFs exhibited higher selectivities to propene than pristine CNFs. The N-CNFs were the most active but the least selective of the catalysts tested here. Our results also show that the type of P precursor affects the selectivity to propene and that CNFs modified using triphenylphosphine as the precursor provided the highest selectivity at isoconversion. PMID:25138580

  7. Tuning the acid/metal balance of carbon nanofiber-supported nickel catalysts for hydrolytic hydrogenation of cellulose.

    Science.gov (United States)

    Van de Vyver, Stijn; Geboers, Jan; Schutyser, Wouter; Dusselier, Michiel; Eloy, Pierre; Dornez, Emmie; Seo, Jin Won; Courtin, Christophe M; Gaigneaux, Eric M; Jacobs, Pierre A; Sels, Bert F

    2012-08-01

    Carbon nanofibers (CNFs) are a class of graphitic support materials with considerable potential for catalytic conversion of biomass. Earlier, we demonstrated the hydrolytic hydrogenation of cellulose over reshaped nickel particles attached at the tip of CNFs. The aim of this follow-up study was to find a relationship between the acid/metal balance of the Ni/CNFs and their performance in the catalytic conversion of cellulose. After oxidation and incipient wetness impregnation with Ni, the Ni/CNFs were characterized by various analytical methods. To prepare a selective Ni/CNF catalyst, the influences of the nature of oxidation agent, Ni activation, and Ni loading were investigated. Under the applied reaction conditions, the best result, that is, 76 % yield in hexitols with 69 % sorbitol selectivity at 93 % conversion of cellulose, was obtained on a 7.5 wt % Ni/CNF catalyst prepared by chemical vapor deposition of CH(4) on a Ni/?-Al(2)O(3) catalyst, followed by oxidation in HNO(3) (twice for 1 h at 383 K), incipient wetness impregnation, and reduction at 773 K under H(2). This preparation method leads to a properly balanced Ni/CNF catalyst in terms of Ni dispersion and hydrogenation capacity on the one hand, and the number of acidic surface-oxygen groups responsible for the acid-catalyzed hydrolysis on the other. PMID:22730195

  8. Biomimetically synthesized silica-carbon nanofiber architectures for the development of highly stable electrochemical biosensor systems.

    Science.gov (United States)

    Vamvakaki, Vicky; Hatzimarinaki, Maria; Chaniotakis, Nikos

    2008-08-01

    Biomimetically synthesized silica and conductive activated carbon nanofibers (CNFs) are used in a synergistic manner for the development of a novel electrochemical biosensor system. Poly(L-lysine) templated silica grows and encapsulates the CNF-immobilized enzyme generating a highly stabilizing nanostructured environment for the underlying protein. Concurrently, CNFs provide both the required surface area for the high-capacity enzyme immobilization required in biosensors as well as direct electron transfer to the inner platinum transducer. As a result, this silica/nanofiber superstructure is an ideal architecture for the development of electrochemical biosensor systems that can withstand exposure to extreme operational conditions, such as high temperatures or the presence of proteases. Acetylcholine esterase is used as the model catalyst and with the aid of spectroscopic data it is shown that the observed high operational stability of the biosensor is due to the direct interaction of the protein with the silica backbone, as well as due to the nanostructured enzyme confinement. PMID:18593196

  9. Mechanical and Electrical Characterization of Entangled Networks of Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    Arash K. Mousavi

    2014-06-01

    Full Text Available Entangled networks of carbon nanofibers are characterized both mechanically and electrically. Results for both tensile and compressive loadings of the entangled networks are presented for various densities. Mechanically, the nanofiber ensembles follow the micromechanical model originally proposed by van Wyk nearly 70 years ago. Interpretations are given on the mechanisms occurring during loading and unloading of the carbon nanofiber components.

  10. Graphene wrapping as a protective clamping layer anchored to carbon nanofibers encapsulating Si nanoparticles for a Li-ion battery anode.

    Science.gov (United States)

    Shin, Jungwoo; Park, Kyusung; Ryu, Won-Hee; Jung, Ji-Won; Kim, Il-Doo

    2014-11-01

    Carbon nanofibers encapsulating Si nanoparticles (CNFs/SiNPs) were prepared via an electrospinning method and chemically functionalized with 3-aminopropyltriethoxysilane (APS) to be grafted onto graphene oxide (GO). As a result, the thin and flexible GO, which exhibits a negative charge in aqueous solution, fully wrapped around the APS-functionalized CNFs with a positive surface charge via electrostatic self-assembly. After the formation of chemical bonds between the epoxy groups on GO and the amine groups in APS via an epoxy ring opening reaction, the GO was chemically reduced to a reduced graphene oxide (rGO). Electrochemical and morphological characterizations showed that capacity loss by structural degradation and electrolyte decomposition on Si surface were significantly suppressed in the rGO-wrapped CNFs/SiNPs (CNFs/SiNPs@rGO). Superior capacities were consequently maintained for up to 200 cycles at a high current density (1048 mA h g(-1) at 890 mA g(-1)) compared to CNFs/SiNPs without the rGO wrapping (304 mA h g(-1) at 890 mA g(-1)). Moreover, the resistance of the SEI layer and charge transfer resistance were also considerably reduced by 24% and 88%, respectively. The described graphene wrapping offers a versatile way to enhance the mechanical integrity and electrochemical stability of Si composite anode materials. PMID:25219404

  11. 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.

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

    OpenAIRE

    André Navarro de Miranda; Luiz Claudio Pardini; Carlos Alberto Moreira dos Santos; Ricardo Vieira

    2011-01-01

    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/e...

  13. Hydrothermal synthesis of ?-nickel hydroxide nanocrystalline thin film and growth of oriented carbon nanofibers

    International Nuclear Information System (INIS)

    Novel well-crystallized ?-nickel hydroxide nanocrystalline thin films were successfully synthesized at low temperature on the quartz substrates by hydrothermal method, and the oriented carbon nanofibers (CNFs) were prepared by acetylene cracking at 750 deg. C on thin film as the catalyst precursor. High resolution transmission electron microscopy (HR-TEM) measurement shows that thin films were constructed mainly with hexagonal ?-nickel hydroxide nanosheets. The average diameter of the nanosheets was about 80 nm and thickness about 15 nm. Hydrothermal temperature played an important role in the film growth process, influencing the morphologies and catalytic activity of the Ni catalysts. Ni thin films with high catalytic activity were obtained by reduction of these Ni(OH)2 nanocrystalline thin films synthesized at 170 deg. C for 2 h in hydrothermal condition. The highest carbon yield was 1182%, and was significantly higher than the value of the catalyst precursor which was previously reported as the carbon yield (398%) for Ni catalysts. The morphology and growth mechanism of oriented CNFs were also studied finally.

  14. Sacrificial bonds in stacked-cup carbon nanofibers: biomimetic toughening mechanisms for composite systems.

    Science.gov (United States)

    Palmeri, Marc J; Putz, Karl W; Brinson, L Catherine

    2010-07-27

    Many natural composites, such as nacre or bone, achieve exceptional toughening enhancements through the rupture of noncovalent secondary bonds between chain segments in the organic phase. This "sacrificial bond" rupture dissipates enormous amounts of energy and reveals significant hidden lengths due to unraveling of the highly coiled macromolecules, leaving the structural integrity of their covalent backbones intact to large extensions. In this work, we present the first evidence of similar sacrificial bond mechanisms in the inorganic phase of composites using inexpensive stacked-cup carbon nanofibers (CNF), which are composed of helically coiled graphene sheets with graphitic spacing between adjacent layers. These CNFs are dispersed in a series of high-performance epoxy systems containing trifunctional and tetrafunctional resins, which are traditionally difficult to toughen in light of their highly cross-linked networks. Nonetheless, the addition of only 0.68 wt % CNF yields toughness enhancements of 43-112% for the various blends. Analysis of the relevant toughening mechanisms reveals two heretofore unseen mechanisms using sacrificial bonds that complement the observed crack deflection, rupture, and debonding/pullout that are common to many composite systems. First, embedded nanofibers can splay discretely between adjacent graphitic layers in the side walls; second, crack-bridging nanofibers can unravel continuously. Both of these mechanisms entail the dissipation of the pi-pi interactions between layers in the side walls without compromising the structural integrity of the graphene sheets. Moreover, increases in electrical conductivity of approximately 7-10 orders of magnitude were found, highlighting the multifunctionality of CNFs as reinforcements for the design of tough, inexpensive nanocomposites with improved electrical properties. PMID:20568708

  15. Novel continuous carbon and ceramic nanofibers and nanocomposites

    Science.gov (United States)

    Wen, Yongkui

    2004-12-01

    Manufacturing of carbon nanofibers from PAN precursor is described in Chapter 2 of the dissertation. The electrospun nanofibers were continuous, uniform in diameter, and the samples didn't contain impurities, unlike carbon nanotubes or vapor grown carbon fibers. Systematic studies on the electrospinning parameters showed that nanofiber diameter could be varied in a range of 80 to 1800 nm. XRD studies on the carbon nanofibers fired at different temperatures showed that higher temperature resulted in better nanostructure. Fracture-free random carbon nanofiber sheets were produced by stretch-stabilization and carbonization for the first time. Toughening effects of random as-spun PAN, stabilized PAN, and carbon nanofibers on Mode I and Mode II interlaminar fracture of advanced carbon-epoxy composites were examined by DCB and ENF tests respectively in Chapter 3. The results showed that the interlaminar fracture toughness increased the most with carbon nanofiber reinforcement. 200% improvement in Mode I fracture toughness and 60% in Mode II fracture toughness were achieved with a minimum increase of weight. SEM fractographic analysis showed nanofiber pullout and crack bridging as the main nanomechanisms of toughening. Chapter 4 describes manufacturing of aligned carbon nanofibers and nanocomposites by a modified electrospinning technique. Constant-load stretch-stabilization was applied on carbon nanofibers for the first time. Analysis showed that mechanical properties of nanofibers and nanocomposites improved with stretch-stabilization and alignment of carbon nanofibers. Nanofabrication of ceramic 3Al2O3-2SiO2, SiO2-TiO2 nanofibers by a novel combination of sol-gel and electrospinning techniques invented recently at UNL is described in Chapters 5. The 3Al2O3-2SiO2, SiO2-TiO 2 nanofibers were continuous, non circular in cross section and had crystalline structure after high temperature calcination. Effects of the process parameters on their geometry and structure were studied. In Chapter 6, ZrO2 nanofibers were prepared using commercial and novel polymer-containing sol-gel precursors. The ZrO2 nanofibers were continuous, circular in cross section, and had diameters as small as 80 mn. Aligned ZrO2 nanofibers were prepared using newly developed polymer containing composite precursor for the first time. The possibility of nanomanufacturing of nanocrystalline continuous nanofibers was demonstrated. The results of this dissertation will have an impact in the field of high performance fibers and nanocomposites. This study is expected to catalyze research on advanced continuous nanofibers and may pave way for consideration of continuous advanced electrospun nanofibers as reinforcement in the next generation nanocomposites. (Abstract shortened by UMI.)

  16. One-step preparation of hydrophilic carbon nanofiber containing magnetic Ni nanoparticles materials and their application in drug delivery.

    Science.gov (United States)

    Wang, Chih-Jen; Chen, Tse-Ching; Lin, Jarrn-Horng; Huang, Pei-Rong; Tsai, Hsing-Jui; Chen, Ching-Shiun

    2015-02-15

    A one-step process for the synthesis of hydrophilic carbon nanofibers (CNFs) through CO2 hydrogenation on NiNa/Al2O3 was developed for the loading and targeted delivery of the anticancer drug doxorubicin (DOX). CNFs that were synthesized on NiNa/Al2O3 for 9 h at 500 °C exhibited an adequate magnetic response and a large content of hydrophilic oxygen-containing functional groups on the carbon surface, resulting in excellent colloidal solution. The CNF material exhibited a highly efficient capacity for DOX adsorption, particularly at pH 9.0. The loading and release of DOX was strongly pH dependent, possibly due to electrostatic and ?-? stacking interactions between DOX and CNF sample. The Langmuir isotherm and pseudo second-order kinetics of DOX-loaded CNFs were well-modeled for the process of DOX adsorption. DOX-loaded CNF targeted cancer cells more selectively and effectively than free DOX and exhibited a marked tendency to kill HeLa cancer cells and reduced toxicity to normal human primary fibroblast (HPF) cells. PMID:25460704

  17. Carbon nanofibers decorated with platinum nanoparticles: a novel three-dimensional platform for non-enzymatic sensing of hydrogen peroxide

    International Nuclear Information System (INIS)

    We have developed a 3-dimensional (3-D) electrochemical sensor for highly sensitive detection of hydrogen peroxide (H2O2). Porous 3-D carbon nanofibers (CNFs), prepared by electrospinning, served as scaffold on a glassy carbon electrode. The 3-D CNFs were functionalized with platinum nanoparticles (Pt-NPs) by in-situ gas-phase decomposition of platinum salts at high temperature. The Pt-NPs act as an electrocatalyst for the decomposition of H2O2. TEM revealed that large amounts of Pt-NPs are deposited in the electrospun CNFs electrode even without using any stabilizer or reducing reagent. The sensor was investigated by cyclic voltammetry and amperometry and displays a good response to H2O2 with a linear range between 10 ?M and 15 mM (R?=?0.9994), a low detection limit (3.4 ?M at a signal-to-noise ratio of 3), and a response time of 3 s. The sensor shows excellent stability and selectivity. (author)

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

    International Nuclear Information System (INIS)

    Carbon nanofibers (CNFs) containing boron and nitrogen are prepared from polyacrylonitrile and boron trioxide (B2O3) by using simple electrospinning. The B2O3 introduction into a PAN solution causes a porous structure with stabilized [O]BN functional groups to develop in the processes of stabilization and carbonization. The pore structure and the functional groups such as B atoms and [O]BN introduce synergistic effects by not only increasing the power density but also the energy density, as shown by the results. The energy storage capabilities of the electrode prepared from 20 wt% B2O3 added to the PAN solution are as follows: a capacitance of 184.0 F g?1 and an energy density of 18.7–25.2 Wh kg?1 in the respective power density range of 400–10,000 W kg?1 in 6 M KOH electrolyte. Hence, these CNFs exhibit a very promising potential as electrode materials for electrical double-layer capacitors due to their unique microstructure and proper proportion of heteroatoms

  19. A nonenzymatic sensor for xanthine based on electrospun carbon nanofibers modified electrode.

    Science.gov (United States)

    Tang, Xiaofeng; Liu, Yang; Hou, Haoqing; You, Tianyan

    2011-02-15

    Xanthine (Xa) determination is of considerable importance in clinical analysis and food quality control. Therefore, a sensitive nonenzymatic amperometric sensor for Xa based on carbon nanofibers (CNFs) has been proposed. The CNFs, which were prepared by electrospinning technique and subsequent thermal treatment, were used to modify carbon paste electrode (CNF-CPE) to construct the amperometric sensor device without any oxidation pretreatment. In application to Xa electrochemical determination, the CNF-CPE exhibited high electrocatalytic activity and fast amperometric response. Various experimental parameters, such as pH and applied potential were optimized. Under the optimal conditions, the dynamic linear range of Xa was 0.03-21.19 ?M (R=0.9992) with the detection limit low to 20 nM (S/N=3). With good selectivity and sensitivity, the present system was successfully applied to estimate the freshness of fish and determine Xa in human urine, which provides potential application in food quality control and clinical analysis. PMID:21238729

  20. Electrocatalytic properties of Pt/carbon composite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Lin Zhan; Ji Liwen [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); 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)], E-mail: xiangwu_zhang@ncsu.edu

    2009-11-30

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

  1. Electrocatalytic properties of Pt/carbon composite nanofibers

    International Nuclear Information System (INIS)

    Pt/carbon composite nanofibers were prepared by electrodepositing Pt nanoparticles directly onto electrospun carbon nanofibers. The morphology and size of Pt nanoparticles were controlled by the electrodeposition time. The resulting Pt/carbon composite nanofibers were characterized by running cyclic voltammograms in 0.20 M H2SO4 and 5.0 mM K4[Fe(CN)6] + 0.10 M KCl solutions. The electrocatalytic activities of Pt/carbon composite nanofibers were measured by the oxidation of methanol. Results show that Pt/carbon composite nanofibers possess the properties of high active surface area and fast electron transfer rate, which lead to a good performance towards the electrocatalytic oxidation of methanol. It is also found that the Pt/carbon nanofiber electrode with a Pt loading of 0.170 mg cm-2 has the highest activity.

  2. Carbon nanofibers: a versatile catalytic support

    Scientific Electronic Library Online (English)

    Nelize Maria de Almeida, Coelho; Jomar Livramento Barros, Furtado; Cuong, Pham-Huu; Ricardo, Vieira.

    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 electr [...] odes. 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.

  3. 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.

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

    International Nuclear Information System (INIS)

    Surface functionalization of carbon nanofibers (CNFs) with aminopropyl terminated polydimethylsiloxane [(PDMS-NH2)] and other organic diamines was achieved using carbodiimide chemistry. The carbodiimide chemistry provides faster reaction rate so that the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. CNF functionalized with PDMS-NH2 fibers were further functionalized with oligomer of polyimide (6FDA-BisP) using imidization reaction. The formation of block copolymer on the surface of CNF is proposed as an effective method to engineer the interphase between the fiber and the polymer, which is essential to modulate and enhance the properties of the nanocomposite. The efficiency of the carbodiimide chemistry to functionalize amine terminated groups on CNF and the functionalization of block copolymer was characterized using thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy.

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

    Science.gov (United States)

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

    2014-12-01

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

  6. A Novel Carbon Nanofibers Grown on Glass Microballoons Immunosensor: A Tool for Early Diagnosis of Malaria

    Directory of Open Access Journals (Sweden)

    Emmanuel Gikunoo

    2014-08-01

    Full Text Available This paper presents a novel method for direct detection of Plasmodium falciparum histidine rich protein-2 (PfHRP-2 antigen using carbon nanofiber (CNF forests grown on glass microballoons (NMBs. Secondary antibodies specific to PfHRP-2 densely attached to the CNFs exhibit extraordinary ability for the detection of minute concentrations of Plasmodium species. A sandwich immunoassay protocol was employed, where a glass substrate was used to immobilize primary antibodies at designated capture zones. High signal amplification was obtained in both colorimetric and electrical measurements due to the CNFs through specific binding. As a result, it was possible to detect PfHRP-2 levels as low as 0.025 ng/mL concentration in phosphate buffered saline (PBS using a visual signal within only 1 min of test duration. Lower limits of 0.01 ng/mL was obtained by measuring the electrical resistivity of the capture zone. This method is also highly selective and specific in identifying PfHRP-2 and other Plasmodium species from the same solution. In addition, the stability of the labeling mechanism eliminates the false signals generated by the use of dyes in current malaria rapid diagnostic test kits (MRDTs. Thus, the rapid, sensitive and high signal amplification capabilities of NMBs is a promising tool for early diagnosis of malaria and other infectious diseases.

  7. Long-term cycling studies on electrospun carbon nanofibers as anode material for lithium ion batteries.

    Science.gov (United States)

    Wu, Yongzhi; Reddy, M V; Chowdari, B V R; Ramakrishna, S

    2013-11-27

    Electrospun carbon nanofibers (CNF) have been prepared at different calcination temperatures for a prolonged time (12 h) derived from electrospun polyacrylonitrile (PAN) membranes. They are studied as anode materials in lithium ion batteries due to their high reversible capacity, improved long-term cycle performance, and good rate capacity. The fibrous morphologies of fresh electrodes and tested samples for more than 550 cycles have been compared; cyclic voltammogram (CV) has also been studied to understand the lithium intercalation/deintercalation mechanism of 1D nanomaterials. CNFs demonstrate interesting galvanostatic performance with fading capacity after the first few cycles, and the capacity increases during long-term cycling. The increasing capacity is observed accompanied by volumetric expansion on the nanofibers' edge. Results of rate capacity have also been explored for all CNF samples, and their stable electrochemical performances are further analyzed by the galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). CNF carbonized at 800 °C is found to have a larger lithium ion storage ability and better cyclic stability than that carbonized at 600 and 1000 °C. PMID:24171411

  8. Copper-doped Li4Ti5O12/carbon nanofiber composites as anode for high-performance sodium-ion batteries

    Science.gov (United States)

    Ge, Yeqian; Jiang, Han; Fu, Kun; Zhang, Changhuan; Zhu, Jiadeng; Chen, Chen; Lu, Yao; Qiu, Yiping; Zhang, Xiangwu

    2014-12-01

    Lithium titanium oxide (Li4Ti5O12) is a promising anode material, owing to its superior safety and reliability. However, the main challenge of Li4Ti5O12 is the low material conductivity which restricts its electrochemical performance. In order to use Li4Ti5O12 in practical sodium-ion batteries, copper-doped Li4Ti5O12 (Li4-xCuxTi5O12, x = 0, 0.05, 0.1) nanoparticles were prepared to enhance the electronic conductivity. Copper-doped Li4Ti5O12 nanoparticles were then embedded in continuous carbon nanofibers (CNFs), which gave rise to fast electron transfer along the fiber direction. After copper-doping and CNF embedding, the resultant copper-doped Li4Ti5O12/CNFs achieved excellent reversible capacity (158.1 mAh g-1) at 30 mA g-1, high coulombic efficiency (99.87%), and good capacity retention (91%) after 150 cycles. In addition, copper-doped Li4Ti5O12/CNFs also exhibited good rate capability. It is, therefore, demonstrated that copper-doped Li4Ti5O12/CNFs are promising anode candidate.

  9. Improving the cyclability and rate capability of carbon nanofiber anodes through in-site generation of SiOx-rich overlayers

    International Nuclear Information System (INIS)

    SiOx-rich overlayed carbon nanofibers (SiOx-CNFs) are facilely fabricated through the electrospinning of tetraethyl orthosilicate (TEOS) and polyacrylonitrile (PAN) solution and subsequent hydrolyzation and heat treatments. The SiOx-rich overlayer is apparently observed by high-resolution transmission electron microscopy (HR-TEM), which is also identified using X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). The SiOx-CNF electrode shows greatly improved cycle stability and rate capability, remaining 84.2% of its initial discharge capacity in contrast to only 61.4% for pure CNFs and exhibiting a reversible capacity of 288 mAh g?1 at 2 A g?1 compared with that (218 mAh g?1) of pure CNFs. This result is ascribed to the formation of a dense and stable SEI film and the highly improved ionic conductivity of SiOx-CNFs during the Li+ insertion/extraction processes. These results suggest that the introduction of SiOx-rich overlayer onto electrodes is an effective strategy to enhance the stability of SEI film and facilitate the surface Li-ion transfer of electrodes, and thus to improve their cycle stability and rate capability

  10. On the importance of the structure in the electrical conductivity of ?shbone carbon nano?bers

    OpenAIRE

    Sebastia?n Del Ri?o, David; Ruiz, Andre?s G.; Suelves Laiglesia, Isabel; Moliner A?lvarez, Rafael; La?zaro Elorri, Mari?a Jesu?s

    2012-01-01

    Carbon nanofibers (CNFs) have a remarkable electrical conductivity resulting highly attractive for different applications such as composites or electronics due to their high quality/price ratio. Although it is known that their graphitic character provides a high conductivity, very little is known about the influence of the nanofibers structure on that property. In this study, CNFs characterized by different physical properties are prepared at diverse synthesis temperatures within ...

  11. Sandwich-lithiation and longitudinal crack in amorphous silicon coated on carbon nanofibers.

    Science.gov (United States)

    Wang, Jiang Wei; Liu, Xiao Hua; Zhao, Kejie; Palmer, Andrew; Patten, Erin; Burton, David; Mao, Scott X; Suo, Zhigang; Huang, Jian Yu

    2012-10-23

    Silicon-carbon nanofibers coaxial sponge, with strong mechanical integrity and improved electronic conductivity, is a promising anode structure to apply into commercial high-capacity lithium ion batteries. We characterized the electrochemical and mechanical behaviors of amorphous silicon-coated carbon nanofibers (a-Si/CNFs) with in situ transmission electron microscopy (TEM). It was found that lithiation of the a-Si coating layer occurred from the surface and the a-Si/CNF interface concurrently, and propagated toward the center of the a-Si layer. Such a process leads to a sandwiched Li(x)Si/Si/Li(x)Si structure, indicating fast Li transport through the a-Si/CNF interface. Nanocracks and sponge-like structures developed in the a-Si layer during the lithiation-delithiation cycles. Lithiation of the a-Si layer sealed in the hollow CNF was also observed, but at a much lower speed than the counterpart of the a-Si layer coated on the CNF surface. An analytical solution of the stress field was formulated based on the continuum theory of finite deformation, explaining the experimental observation of longitudinal crack formation and general mechanical degradation mechanism in a-Si/CNF electrode. PMID:22984869

  12. Preparation of interconnected carbon nanofibers as electrodes for supercapacitors

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The interconnected carbon nanofibers were prepared by an electrospinning technique. • The interconnected fibers developed conductive pathways. • The interconnected fibers showed 24% enhancement on the specific capacitance. • The interconnected fibers are promising to be used as electrodes for supercapacitors. - Abstract: The interconnected carbon nanofibers were prepared by an electrospinning technique using a polymer solution composed of polyacrylonitrile (PAN), poly(acrylonitrile-co-butadiene (PAN-co-PB) copolymer, and N,N-dimethylformamide. Post-treatment including stabilization at 250 °C and carbonization at 800 °C converted electrospun fibers to bonded carbon nanofibers. The formation of interconnected carbon nanofibers was attributed to the decomposition of PB, which reduced the viscosity of nanofibers and caused the fusion of connecting points. As a result, the conductive pathways developed, leading to an increase in both the electrical conductivity and microcrystallite size. Electrochemical measurements revealed that the specific capacitance of the 90:10 PAN/PAN-co-PB derived carbon nanofibers was 170.2 F/g, which was about 24% higher than that of the neat PAN-derived carbon nanofibers. Furthermore, the fibers showed good cycling stability of energy storage with the retention ratio of 100% after 2000 cycles. Our results corroborated the advantage of these interconnected nanofibers

  13. The role of carbon nanofiber defects on the electrical and mechanical properties of CNF-based resins

    Science.gov (United States)

    Guadagno, Liberata; Raimondo, Marialuigia; Vittoria, Vittoria; Vertuccio, Luigi; Lafdi, Khalid; De Vivo, Biagio; Lamberti, Patrizia; Spinelli, Giovanni; Tucci, Vincenzo

    2013-08-01

    Heat treatment of carbon nanofibers has proven to be an effective method in removing defects from carbon nanofibers, causing a strong increase in their structural perfection and thermal stability. It affects the bonding states of carbon atoms in the nanofiber structure and causes a significant transformation in the hybridization state of the bonded carbon atoms. Nanofilled resins made of heat-treated CNF show significant increases in their electrical conductivity even at low concentrations. This confirms that enhancement in the perfection of the fiber structure with consequent change in the morphological features plays a prominent role in affecting the electrical properties. Indeed heat-treated CNFs display a stiff structure and a smooth surface which tends to lower the thickness of the unavoidable insulating epoxy layer formed around the CNF which, in turn, plays a fundamental role in the electrical transport properties along the conducting clusters. This might be very beneficial in terms of electrical conductivity but might have negligible effect on the mechanical properties.

  14. Electron field emission from room temperature grown carbon nanofibers

    OpenAIRE

    Smith, Rc; Carey, Jd; Poa, Chp; Cox, Dc; Silva, Srp

    2004-01-01

    The observation of field induced electron emission from room temperature grown carbon nanofibers at low (5 V/mum) macroscopic electric fields is reported. The nanofibers were deposited using methane as a source gas in a conventional rf plasma enhanced chemical vapor deposition reactor using a Ni metal catalyst previously subjected to an Ar plasma treatment. Analysis of the scanning electron microscopy images of the nanofibers show them to possess an average diameter of 300 nm and that the nan...

  15. Highly conductive electrospun carbon nanofiber/MnO2 coaxial nano-cables for high energy and power density supercapacitors

    Science.gov (United States)

    Zhi, Mingjia; Manivannan, Ayyakkannu; Meng, Fanke; Wu, Nianqiang

    2012-06-01

    This paper presents highly conductive carbon nanofiber/MnO2 coaxial cables in which individual electrospun carbon nanofibers are coated with an ultrathin hierarchical MnO2 layer. In the hierarchical MnO2 structure, an around 4 nm thick sheath surrounds the carbon nanofiber (CNF) in a diameter of 200 nm, and nano-whiskers grow radically outward from the sheath in view of the cross-section of the coaxial cables, giving a high specific surface area of MnO2. The CNFs are synthesized by electrospinning a precursor containing iron acetylacetonate (AAI). The addition of AAI not only enlarges the specific surface area of the CNF but also greatly enhances their electronic conductivity, which leads to a dramatic improvement in the specific capacitance and the rate capability of the CNF/MnO2 electrode. The AAI-CNF/MnO2 electrode shows a specific capacitance of 311 F g-1 for the whole electrode and 900 F g-1 for the MnO2 shell at a scan rate of 2 mV s-1. Good cycling stability, high energy density (80.2 Wh kg-1) and high power density (57.7 kW kg-1) are achieved. This work indicates that high electronic conductivity of the electrode material is crucial to achieving high power and energy density for pseudo-supercapacitors.

  16. 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 chemical vapor deposition using Cu and Fe as the metal catalysts. 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. Following ultrasonication, Fe nanoparticles are dislodged and replaced with glucose oxidase. The electrochemical tests show that the prepared electrode has fast response current, electrochemical stability, and high electron transfer rate, corroborated by its CV and calibration curves. Highlights: • Fe–Cu-grown web of carbon micro-nanofiber-based electrode was prepared. • The carbon electrode was applied to detect glucose in liquids. • It has electrochemical stability and high electron transfer rate. • The electrode is cost-effective and simple to develop. • It has a stable immobilization matrix for enzymes.

  17. ADSORPTION OF MULTIWALLED CARBON NANOTUBES ON ELECTROSPUN POLYCAPROLACTON NANOFIBERS

    Scientific Electronic Library Online (English)

    KHALID, SAEED; PARK, SOO-YOUNG; MOHAMMAD, ISHAQ.

    2009-12-01

    Full Text Available SciELO Chile | Language: English Abstract in english Polycaprolacton (PCL) and multiwalled carbon nanotubes/PCL (P-MWNT/PCL) were prepared by electrospinning technique. The average diameter of the nanofibers was below 400 nm. The mechanical properties of the P-MWNT/PCL nanofibers were higher than that of neat PCL nanofibers. It was also found that the [...] mechanical properties of the composite nanofibers were decreased as increased the amount of P-MWNTs, which were due to the poor dispersion of the P-MWNTs in the PCL matrix or agglomeration of MWNTs at high concentration. The thermal stability of the P-MWNT/PCL nanofibers was higher than PCL nanofibers. The conductivity of the adsorbed P-MWNT on PCL (

  18. Potential applications of nanofiber textile covered by carbon coatings

    Directory of Open Access Journals (Sweden)

    Z. Ro?ek

    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.

  19. Electrochemical determination of L-Tryptophan, L-Tyrosine and L-Cysteine using electrospun carbon nanofibers modified electrode.

    Science.gov (United States)

    Tang, Xiaofeng; Liu, Yang; Hou, Haoqing; You, Tianyan

    2010-03-15

    A novel and simple method for the direct and quantitative determination of L-tryptophan (Trp), L-tyrosine (Tyr) and L-cysteine (Cys) was proposed in this work. Carbon nanofibers (CNFs), made by electrospinning technique, were used to modify carbon paste electrode (CPE) without any treatment to study the electrochemical behaviors of the three amino acids using cyclic voltammetry (CV) and constant potential amperometric method. The results demonstrated that the CNFs modified carbon paste electrode (CNF-CPE) exhibited high electrocatalytic activity and good analytical performance towards the oxidation of the three amino acids. The linear ranges of Trp, Tyr and Cys were 0.1-119, 0.2-107 and 0.15-64 microM with correlation coefficients of 0.9994, 0.9985 and 0.9996, respectively. All the detection limits of the analytes were 0.1 mM (S/N=3). In addition, the CNF-CPE displayed good reproducibility, high sensitivity and good selectivity towards the determination of the amino acids, making it suitable for the determination of Trp, Tyr and Cys in clinical and medicine. PMID:20152470

  20. Enhancing the rate performance of graphite anodes through addition of natural graphite/carbon nanofibers in lithium-ion batteries

    International Nuclear Information System (INIS)

    Highlights: ? Internal pores of graphite increased the rate property of anode in Li-ion battery. ? Added NG/CNFs into graphite successfully increased the internal pores. ? Introduced internal pores suppressed the anodic volume change in charge–discharge. - Abstract: Mesophase pitch-derived synthetic graphite was hybridized with natural graphite/carbon nanofiber (NG/CNF) composites prepared by mechanical mixing, carbonization, and graphitization processes. Addition of the NG/CNF composites introduced effective internal pores inside the synthetic graphite matrix, thereby improving the rate performance, 1st cycle coulombic efficiency, and cyclability. Hybridized graphite with 10 wt% of added NG/CNF composite exhibited the best rate performance, with a discharge capacity retention rate of over 90% after a 5 C discharge test

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

    Scientific Electronic Library Online (English)

    André Navarro de, Miranda; Luiz Claudio, Pardini; Carlos Alberto Moreira dos, Santos; Ricardo, Vieira.

    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 f [...] iber/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.

  2. Preparation of a new adsorbent from activated carbon and carbon nanofiber (AC/CNF for manufacturing organic-vacbpour respirator cartridge

    Directory of Open Access Journals (Sweden)

    Forushani Abbas Rahimi

    2013-01-01

    Full Text Available Abstract In this study a composite of activated carbon and carbon nanofiber (AC/CNF was prepared to improve the performance of activated carbon (AC for adsorption of volatile organic compounds (VOCs and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores. Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett and Teller’s (BET technique and electron microscopy respectively. Prepared composite adsorbent was tested for benzene, toluene and xylene (BTX adsorption and then employed in an organic respirator cartridge in granular form. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nm were formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight.

  3. Au@Ag nanorods based electrochemical immunoassay for immunoglobulin G with signal enhancement using carbon nanofibers-polyamidoamine dendrimer nanocomposite.

    Science.gov (United States)

    Ma, Lina; Ning, Danlei; Zhang, Hongfang; Zheng, Jianbin

    2015-06-15

    Au@Ag nanorods (Au@AgNRs) was utilized to construct a novel sandwich-type electrochemical immunosensor for the detection of immunoglobulin G (IgG). The sensor was prepared by immoblizing capture antibodies on the amine-terminated nanocomposite of carbon nanofibers-polyamidoamine dendrimer (CNFs-PAMAM), whilst the trace tag was prepared by loading anti-human IgG on Au@AgNRs. The "built-in" Ag layer on Au nanorods was characterized by UV-vis extinction spectra, transmission electron microscopy and energy dispersive spectroscopy. The results of cyclic voltammetry indicated that modifying CNFs-PAMAM nanocomposite on glassy carbon electrode enabled 177 times of peak current increase of Ag in the bimetallic nanorods. The peak current was quantitatively related with the concentration of the target protein IgG via the formation of immunocomplex. After the parameter optimization, the oxidative peak current of silver was proportional to the concentration of IgG in a wide linear range of six orders of magnitude with a low detection limit of 0.5fgmL(-1). Besides, this sensor showed acceptable reproducibility and stability, and thus the strategy reported here has great promise for extension to the other disease biomarkers. PMID:25569874

  4. Friction of partially embedded vertically aligned carbon nanofibers inside elastomers

    International Nuclear Information System (INIS)

    Vertically aligned carbon nanofibers partially embedded inside polyurethane (eVACNFs) are proposed as a robust high friction fibrillar material with a compliant backing. Carbon nanofibers with 50-150 nm in diameter and 20-30 ?m in length are vertically grown on silicon and transferred completely inside an elastomer by vacuum molding. By using time controlled and selective oxygen plasma etching, fibers are partially released up to 5 ?m length. Macroscale friction experiments show that eVACNFs exhibit reproducible effective friction coefficients up to 1. Besides high friction, the proposed fabrication method improves fiber-substrate bond strength, and enables uniform height nanofibers with a compliant backing

  5. 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 coefficient of thermal expansion (CTE) of CNF/epoxy and CNF/syntactic foam composites reinforced with glass microballoons decrease by as much as 11.6% and 38.4%. The experimental CTE values for all of the composites also fit within the bounds of established analytical models predicting the CTE of fiber and particle-reinforced composites. Further thermal studies through dynamic mechanical analysis demonstrated increased thermal stability and damping capability, where the maximum use and glass transition temperatures increase as much as 27.1% and 25.0%, respectively. The electrical properties of CNF reinforced composites are evaluated as well, where the electrical impedance decreases and the dielectric constant increases with addition of CNFs. Such behavior occurs despite the presence of epoxy and glass microballoons, which serve as insulative phases. Such results are useful in design considerations of lightweight composite materials used in weight saving, compressive strength, and damage tolerance applications, such as lightweight aircraft structure reinforcement, automobile components, and buoyancy control with marine submersibles. The results of the analyses have also evaluated certain factors for environmental exposure and temperature extremes, as well as considerations for electronics packaging, all of which have also played a role in shaping avant-garde composite structure designs for efficient, versatile, and long-life service use.

  6. Facilitated transport channels in carbon nanotube/carbon nanofiber hierarchical composites decorated with manganese dioxide for flexible supercapacitors

    Science.gov (United States)

    Wang, Tao; Song, Dengfei; Zhao, Hao; Chen, Jiayi; Zhao, Changhui; Chen, Lulu; Chen, Wanjun; Zhou, Jinyuan; Xie, Erqing

    2015-01-01

    Freestanding carbon nanotube/carbon nanofiber (CNT/CNF) composites are prepared using electrospun CNFs as skeletons in a tubular chemical vapor deposition system. The obtained CNT/CNF composites show a hierarchical structure with a high special surface area, a high conductance (1250 S cm-1 for a 10 mm × 20 mm sample), and a high flexibility. After coated with manganese dioxide (MnO2) via an in-situ redox deposition for 0.5 h (?0.33 mg), the CNT/CNF/MnO2 electrodes show a high specific capacitance of 517 F g-1 at a scan rate of 5 mV s-1, which is about 5.6 time higher than that CNF/MnO2-0.25 h ones with MnO2 of ?0.36 mg. Moreover, this CNT/CNF/MnO2 electrodes show a much higher rate capability (57% at current density of 14 A g-1) than CNF/MnO2 ones (24% at 14 A g-1), and also show a higher cycling stability (maintaining 75% of the initial capacitance at cycle number of 1000). In addition, the symmetric supercapacitor assembled using two piece CNT/CNF/MnO2 electrodes shows their maximum energy density of 3.88 Wh kg-1 at power density of 7000 W kg-1. The capacitance of the assembled capacitor maintains 70% after 100 bending cycles, indicating a good flexibility. These enhancements in EC performances should be due to our designed hierarchical structures. It is suggested that such freestanding flexible CNFs/CNTs/MnO2 hierarchical composites are highly promising for high-performance flexible supercapacitors.

  7. MEMS-based carbon nanotube and carbon nanofiber Cu micro special electric contact

    International Nuclear Information System (INIS)

    Two new electrical contact materials, carbon nanotube (CNT) and carbon nanofiber (CNF), Cu-matrix composite films are prepared by composite electroplating. The microstructure, morphology and physical performance of Cu–CNT/CNF composite films were analyzed by a scanning electron microscope, a Vickers hardness tester and a semiconductor parameter analyzer. The scanning electron microscope images showed that the CNTs/CNFs were dispersed uniformly and combined well in the Cu matrix. Furthermore, the Cu–CNT/CNF composite films show relatively good physical properties, for example the hardnesses of Cu/CNT and Cu/CNF composite films are 156 HV and 207 HV, about 13.9% and 51.1% higher than that of the pure copper plating film (137 HV); the resistivities of CNT/CNF composite plating films are 2.656 × 10?6 ? cm and 1.815 × 10?6 ? cm, lower than those of other Cu-matrix composites such as CuW, 4.35 × 10?6 ? cm, and CuMo, 3.571 × 10?6 ? cm. In addition, CNT and CNF Cu micro special electric contacts have been designed and successfully fabricated by MEMS technology. The arc-erosion behavior of Cu/CNT and Cu/CNF contacts has been examined on an electric arc-erosion apparatus. The test result shows that the arc-erosion losses of Cu/CNT and Cu/CNF contacts are 2.7 mg and 3.0 mg, 22.9% and 14.3% lower than that of pure Cu (3.5 mg) under the same condition

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

    International Nuclear Information System (INIS)

    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.

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Zhongfu [State Key Laboratory of Fine Chemicals, Department of Polymer Science and Engineering, School of Chemical Engineering, Dalian University of Technology, 158 Zhongshan Road, Dalian 116012 (China); Gou Jan [Department of Mechanical, Materials and Aerospace Engineering University of Central Florida, FL 32816 (United States)], E-mail: zhongfuzhao@gmail.com

    2009-01-15

    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.

  11. Functionalization and electrocatalysis on carbon nanofibers

    Science.gov (United States)

    Hogendoorn, Stephanie Ruth

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

  12. Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries.

    Science.gov (United States)

    Li, Bing; Ge, Xiaoming; Goh, F W Thomas; Hor, T S Andy; Geng, Dongsheng; Du, Guojun; Liu, Zhaolin; Zhang, Jie; Liu, Xiaogang; Zong, Yun

    2015-02-01

    An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm(-2)) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications. PMID:25522330

  13. 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)

  14. Characterization of small-scale batch-fabricated carbon nanofiber probes

    International Nuclear Information System (INIS)

    Linear-shaped single carbon nanofibers (CNFs) were batch-grown onto commercially available Si cantilevers for atomic force microscope by the Ar+-ion-irradiation method (9 cantilevers/batch). The force-curve measurements revealed that the long CNF probes (? 1 ?m in length) were as flexible as the carbon nanotubes probes, whereas the short CNF probes (? 400 nm in length) were characterized by the rigid nature similar to the Si probes. Thus, the mechanical properties of CNF probes were controllable by the CNF length. The ion-induced CNF probes were metallic in electrical property, and the higher resolution images in scanning spreading resistance microscopy was attained by the CNF probes than by conventional conductive diamond probes, due to the small tip radius, high aspect ratio and the durability of the CNF probes. Because the small-scale batch-fabricated CNF probes showed good uniformity in the size, mechanical and electrical properties, it was concluded that they are promising as practical conductive SPM probes

  15. Synthesis, characterization and activity pattern of carbon nanofibers based copper/zirconia catalysts for carbon dioxide hydrogenation to methanol: Influence of calcination temperature

    Science.gov (United States)

    Ud Din, Israf; Shaharun, Maizatul S.; Subbarao, Duvvuri; Naeem, A.

    2015-01-01

    A series of novel carbon nanofibers (CNFs) supported bimetallic copper/zirconia catalysts are synthesized by deposition precipitation method and calcined at different temperatures. Calcined catalysts are characterized by various techniques like X-ray diffraction, N2 adsorption-desorption, N2O chemisorption, high resolution transmission electron microscopy, temperature programmed reduction, X-ray photoelectron spectroscopy and temperature programmed desorption (CO2 & NH3). The structure-activity correlation is discussed in details. The results demonstrate 450 °C as optimum calcination temperature for methanol synthesis rate with CO2/H2 feed volume ratio of 1:3. CO2 conversion is found to be directly proportional to copper metallic surface area (SCu), while a linear relationship is observed between methanol synthesis rate and fraction of dispersed Cu.

  16. 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, a carbon capacitor electrode, and a nickel hydroxide battery electrode. By making the capacitor electrode of treated carbon nanofibers instead of another carbon material, one could obtain greater energy-storage capacity.

  17. On the growth of carbon nanofibers on glass with a Cr layer by inductively coupled plasma chemical vapor deposition: The effect of Ni film thickness

    International Nuclear Information System (INIS)

    We have studied the effect of the thickness of catalytic Ni film for the growth of vertically aligned carbon nanofibers (VA-CNFs) on glass substrates coated with a conductive underlayer of Cr. Both the pretreatment process through which the catalytic Ni nanoparticles were formed and the growth of well-aligned CNFs were carried out in an inductively coupled plasma chemical vapor deposition (ICP-CVD) system. The VA-CNFs were characterized by scanning electron microscopy, Raman spectroscopy, as well as field emission measurements. The results of VA-CNF growth shows that as the Ni film thicknesses decrease, not only the length but also the density of the CNFs drop, although the density of catalytic Ni nanoparticles increases. The variation of CNF density with Ni film thicknesses is believed to be a result of the detachment of the CNFs from the substrate, caused by the electrostatic force produced by the plasma sheath electric field, as well as an ion-enhanced chemical etching effect due to atomic/ionic hydrogen, during the ICP-CVD growth. A field emission measurement apparatus based on a metallic probe of spherical anode structure was also constructed in this study. An electrostatic image model was employed to determine the electric field distribution on the cathode surface. Along with the standard F-N field emission model, the dependence of field emission current density on the cathode surface electric field, as well as an effective field enhancement factor, were extractive field enhancement factor, were extracted from the current-voltage measurement results. The threshold electric field (Ethreshold, for a current density of 1 mA/cm2) increases from 9.2 V/?m to 13.1 V/?m, and then drops to 11.5 V/?m for the CNFs with Ni film thicknesses of 20 nm, 30 nm, and 40 nm, respectively. The electrostatic model results also indicate that the 20 nm case has the greatest space-charge effect on the emission current, consistent with the growth results that the 20 nm case has the lowest CNF density. On the other hand, the CNF length of the 40 nm case is longer than that of the 30 nm one, while the densities are nearly the same; as a result, Ethreshold for the 30 nm case is higher

  18. Health effects of exposure to carbon nanofibers: Systematic review, critical appraisal, meta analysis and research to practice perspectives

    International Nuclear Information System (INIS)

    Background: Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and health consequences are qualitative in nature and do not employ an evidence-based assessment. Objective: This research deals with a systematic review, critical appraisal, and meta-analysis designed to examine the potential health effects associated with exposure to CNFs. The utilization of research findings into practice is also explored. Methods: Published articles were obtained from a search of electronic databases and bibliographies of identified articles. A critical appraisal was conducted using an 'Experimental Appraisal Instrument' developed in this study. The meta-analysis was established using statistical techniques with/without the incorporation of overall study quality. The likelihood of utilizing research findings into practice (i.e., from research to practice) was computed using a four-step algorithm based on the criteria of: strength of association, consistency among studies, temporality, biological gradient, type of experimental unit, type of CNF (single- and multi-wall nanotubes), CNF grade (commercial or altered), exposure dose, exposure duration, and support by analogy from the published literature. Results: Twenty-one experimental studies satisfied the inclusion criteria and were performed on human cells, experimental animal models and animal cells as experimental units. The methodological qualities of published studies ranged from 'very poor' tublished studies ranged from 'very poor' to 'excellent', with 'overall study description' scoring 'good' and 'study execution' equal to 'moderate'. The random-effects model was applied in the meta-analysis calculations as heterogeneity was significant at the 10% for all outcomes reported. The mean standardized meta-estimates for the experimental groups were significantly lower than those for the control groups for cell viability and cell death, respectively. Incorporating the effect of overall study quality score widened the gap between the experimental and control groups. Assessment of research findings on the basis of the four-step algorithm revealed that the likelihood of the results to occur in practice is 'somewhat possible' at this time. That is, if exposure conditions to CNF in the reported studies are similar to those in nano-manufacturing plants, it is somewhat possible that CNFs alter the function of human cells resulting in loss of cell viability and cell death. Conclusions: Our findings suggest that it is 'somewhat possible' for the CNF to penetrate the human cells in the targeted organs and to cause cellular damage. Although the weight of evidence is not sufficient, it is advisable that actions be taken to ensure the protection of workers exposed to CNFs, that is, (a) engineering controls should be established to contain exposure to CNF, and (b) simultaneously rigorous personnel protective equipment should be planned to further minimize the risk of CNF exposure.

  19. Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

    Science.gov (United States)

    Li, Bing; Ge, Xiaoming; Goh, F. W. Thomas; Hor, T. S. Andy; Geng, Dongsheng; Du, Guojun; Liu, Zhaolin; Zhang, Jie; Liu, Xiaogang; Zong, Yun

    2015-01-01

    An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm-2) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm-2) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications. Electronic supplementary information (ESI) available: TGA curves of as electrospun Co(ii)-PAN fiber and C-CoPAN900 EDX and XPS spectra of the C-CoPAN900 photo of a home-built Zn-air cell and the preparation method of conventional catalyst electrode; polarization curves and corresponding power density plots of the battery using conventional type cathode of C-CoPN900 and commercial Pt/C catalyst; the electrocatalytic properties of hybrid CNFs obtained from varied weight ratios of PAN to cobalt acetate, e.g. 16 : 1 and 8 : 1, and their corresponding TGA curves; a comparison of the Zn-air battery performance of this work with recent literatures. See DOI: 10.1039/c4nr05988c

  20. Preparation of a New Adsorbent from Activated Carbon and Carbon Nanofiber (AC/CNF for Manufacturing Organic-Vacbpour Respirator Cartridge

    Directory of Open Access Journals (Sweden)

    Mehdi Jahangiri

    2013-01-01

    Full Text Available In this study a composite of activated carbon and carbon nanofiber (AC/CNF was prepared to improve the performance of activated carbon (AC for adsorption of volatile organic compounds (VOCs and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbonnanofibers (CNF were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores.Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett andTeller’s (BET technique and electron microscopy respectively. Prepared composite adsorbent was tested forbenzene, toluene and xylene (BTX adsorption and then employed in an organic respirator cartridge in granularform. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nmwere formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight.

  1. 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 a cheap raw material, graphitic fibers appear to be another useful starting material for mass production of graphene sheets.

  2. 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.

  3. Electrochemical characteristics of activated carbon nanofiber electrodes for supercapacitors

    International Nuclear Information System (INIS)

    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-1 at 10 mA g-1). Elevating the volume fraction of mesopores gave maximum specific capacitance at high current density (100 F g-1 at 1000 mA g-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.

  4. 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.

  5. Formation of wedge-shaped carbon film by chemical vapor deposition method and observation using transmission electron microscopy

    International Nuclear Information System (INIS)

    Unusual morphologies of carbon nanofibers (CNFs) fabricated by the microwave plasma-enhanced chemical vapor deposition method were confirmed by transmission electron microscopy. In particular, the presence and distribution of wedge-shaped carbon films, consisting of amorphous carbon and CNFs, were observed by three-dimensional electron tomography (3D-ET), and their growth mechanisms were modeled. High-resolution transmission electron microscopy (HRTEM) revealed the presence of amorphous carbon on carbon nanofibers. Wedge-shaped carbon films are most likely caused by the bridging of individual CNFs by amorphous carbon from plasmarized carbon. The combination of 3D-ET and HRTEM clearly provides a successful strategy for determining 3D morphologies with characteristic sizes on the nanometer scale

  6. 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 their decreased expression of NMP-22, tumor necrosis factor alpha, and VEGF. Moreover, the adhesion of HUC increased on composites containing more CNF than PU. Overall levels of NMP-22 were significantly lower in HUC than in cancerous UMUC and SCaBER cells on PU:CNF composites. Thus, this study provided a novel nanocomposite consisting of CNF and PU that should be further studied for inhibiting the return of cancerous bladder tissue and for promoting normal non-cancerous bladder tissue formation. PMID:21417694

  7. Platinum on Carbon Nanofibers as Catalyst for Cinnamaldehyde Hydrogenation

    OpenAIRE

    Plomp, A. J.

    2009-01-01

    The aim of the work described in this thesis was to investigate the role and nature of nanostructured carbon materials, oxygen surface groups and promoters on platinum-based catalysts for the selective hydrogenation of cinnamaldehyde. The selective hydrogenation of cinnamaldehyde to cinnamyl alcohol was chosen as a showcase. To establish structure-activity relations, it is crucial to prepare well-defined carbon nanofibers (CNF) supports and well-defined catalytic metal phases on these support...

  8. 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.

  9. 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...

  10. Vertically Aligned Carbon Nanofiber Based Biosensor Platform for Glucose Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Mamun, Khandaker Abdullah Al [ORNL; Tulip, Fahmida S [ORNL; Macarthur, Kimberly C [ORNL; McFarlane, Nicole M [ORNL; Islam, Syed K [ORNL

    2014-01-01

    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

  11. Broad-Band Electrical Conductivity of High Density Polyethylene Nanocomposites with Carbon Nanoadditives: Multiwall Carbon Nanotubes and Carbon Nanofibers

    OpenAIRE

    Linares, A.; Canalda, J. C.; Cagiao, M. E.; Garci?a-gutie?rrez, M. C.; Nogales, A.; Marti?n-gullo?n, I.; Vera, J.; Ezquerra, T. A.

    2008-01-01

    A study is presented of the electrical properties of a series of nanocomposites based on high density polyethylene (HDPE) as a matrix and either carbon nanofiber (CNF) or multiwall carbon nanotube (MWCNT) as a nanoadditive. The measurements of the electrical conductivity over a broad-band of frequencies (10-2 > F/Hz > 109)allow improvement of the description of the electrical properties of polymer nanocomposites based on either carbon nanofibers or carbon nanotubes. Despite the lack of ...

  12. Hierarchical carbon nanostructure design: ultra-long carbon nanofibers decorated with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-28

    Hierarchical carbon nanostructures based on ultra-long carbon nanofibers (CNF) decorated with carbon nanotubes (CNT) have been prepared using plasma processes. The nickel/carbon composite nanofibers, used as a support for the growth of CNT, were deposited on nanopatterned silicon substrate by a hybrid plasma process, combining magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). Transmission electron microscopy revealed the presence of spherical nanoparticles randomly dispersed within the carbon nanofibers. The nickel nanoparticles have been used as a catalyst to initiate the growth of CNT by PECVD at 600 deg. C. After the growth of CNT onto the ultra-long CNF, SEM imaging revealed the formation of hierarchical carbon nanostructures which consist of CNF sheathed with CNTs. Furthermore, we demonstrate that reducing the growth temperature of CNT to less than 500 deg. C leads to the formation of carbon nanowalls on the CNF instead of CNT. This simple fabrication method allows an easy preparation of hierarchical carbon nanostructures over a large surface area, as well as a simple manipulation of such material in order to integrate it into nanodevices.

  13. Significantly improved long-cycle stability in high-rate Li-S batteries enabled by coaxial graphene wrapping over sulfur-coated carbon nanofibers.

    Science.gov (United States)

    Lu, Songtao; Cheng, Yingwen; Wu, Xiaohong; Liu, Jie

    2013-06-12

    Long-term instability of Li-S batteries is one of their major disadvantages compare to other secondary batteries. The reasons for the instability include dissolution of polysulfide intermediates and mechanical instability of the electrode film caused by volume changes during charging/discharging cycles. In this paper, we report a novel graphene-sulfur-carbon nanofibers (G-S-CNFs) multilayer and coaxial nanocomposite for the cathode of Li-S batteries with increased capacity and significantly improved long-cycle stability. Electrodes made with such nanocomposites were able to deliver a reversible capacity of 694 mA h g(-1) at 0.1C and 313 mA h g(-1) at 2C, which are both substantially higher than electrodes assembled without graphene wrapping. More importantly, the long-cycle stability was significantly improved by graphene wrapping. The cathode made with G-S-CNFs with a initial capacity of 745 mA h g(-1) was able to maintain ~273 mA h g(-1) even after 1500 charge-discharge cycles at a high rate of 1C, representing an extremely low decay rate (0.043% per cycle after 1500 cycles). In contrast, the capacity of an electrode assembled without graphene wrapping decayed dramatically with a 10 times high rate (~0.40% per cycle after 200 cycles). These results demonstrate that the coaxial nanocomposites are of great potential as the cathode for high-rate rechargeable Li-S batteries. Such improved rate capability and cycle stability could be attributed to the unique coaxial architecture of the nanocomposite, in which the contributions from graphene and CNFs enable electrodes with improved electrical conductivity, better ability to trap soluble the polysulfides intermediate and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles. PMID:23688337

  14. Manipulation of Bacteriophages with Dielectrophoresis on Carbon Nanofiber Nanoelectrode Arrays

    OpenAIRE

    Madiyar, Foram Ranjeet; Syed, Lateef Uddin; Culbertson, Christopher; Li, Jun

    2013-01-01

    This work describes efficient manipulation of bacteriophage virus particles using a nanostructured dielectrophoresis (DEP) device. The non-uniform electric field for DEP is created by utilizing a nanoelectrode array (NEA) made of vertically aligned carbon nanofibers (VACNFs) versus a macroscopic indium tin oxide electrode in a “points-and-lid” configuration integrated in a microfluidic channel. The capture of the virus particles has been systematically investigated versus the flow velocit...

  15. Effect of carbon nanofiber dispersion on the properties of PIP-SiC/SiC composites

    International Nuclear Information System (INIS)

    SiC/SiC composites with and without dispersed carbon nanofiber were fabricated by the polymer impregnation and pyrolysis process. The effect of dispersing carbon nanofiber on the mechanical and thermal properties of SiC/SiC composites was investigated. The bending strength and elastic modulus of SiC/SiC composites with carbon nanofiber decreased slightly compared to those of the SiC/SiC composites without the nanofiber. On the other hand, the thermal conductivity of SiC/SiC composites increased with increasing amount of dispersed nanofiber. The dominant reason is considered to be that the pore shape changed from an oblong shape perpendicular to the direction of heat flow to an isotropic. The shape change resulted from the dispersed carbon nanofiber.

  16. Physicochemical investigations of carbon nanofiber supported Cu/ZrO2 catalyst

    International Nuclear Information System (INIS)

    Zirconia-promoted copper/carbon nanofiber catalysts (Cu?ZrO2/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 (HNO3). The CNF activated with 5% HNO3 produced higher surface area which is 155 m2/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N2 adsorption-desorption. The results showed that increase of HNO3 concentration reduced the surface area and porosity of the catalyst

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

    OpenAIRE

    Colavita, Paula

    2011-01-01

    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 the nanofib...

  18. Nanowire-directed templating synthesis of metal-organic framework nanofibers and their derived porous doped carbon nanofibers for enhanced electrocatalysis.

    Science.gov (United States)

    Zhang, Wang; Wu, Zhen-Yu; Jiang, Hai-Long; Yu, Shu-Hong

    2014-10-15

    A nanowire-directed templating synthesis of metal-organic framework (MOF) nanofibers has been demonstrated, where ultrathin tellurium nanowires (TeNWs) with excellent dispersivity can act as templates for directed growth and assembly of ZIF-8 nanocrystals (one typical MOF), resulting in the formation of uniform ZIF-8 nanofibers. The as-obtained ZIF-8 nanofibers can be conveniently converted into highly porous doped carbon nanofibers by calcination. Compared with bulk porous carbon by direct carbonization of MOF crystals, these doped carbon nanofibers exhibit complex network structure, hierarchical pores, and high surface area. Further doped by phosphorus species, the co-doped carbon nanofibers exhibit excellent electrocatalytic performance for oxygen reduction reaction, even better than the benchmark Pt/C catalyst. PMID:25244060

  19. 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)

  20. Relationship between Single Walled Carbon Nanotubes Individual Dispersion Behavior and Properties of Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Haji A.

    2013-09-01

    Full Text Available The dispersion stability behavior of single walled carbon nanotube (SWCNT has important effects on morphological and mechanical properties of SWCNT/polymer composite nanofibers. The relationship of the dispersion conditions with morphological and mechanical characteristics for SWCNT / polyacrylonitrile (PAN / polyvinylpyrrolidone (PVP composite nanofibers have been examined. The SEM and TEM analyses of the nanofibers revealed that the deformation in the nanofiber structures increases with increasing SWCNT concentration. Our data indicate that with increasing the amount of SWCNT (from 0 to 2 wt %, the average nanofiber diameter was increased from 163±19 nm to 307±34 nm. Tensile results showed that only 2 wt % SWCNT loading to the electrospun composite nanofibers gave rise to 10-fold and 3-fold increase in the tensile modulus and tenacity of nanofiber layers, respectively. Essentially, high mechanical properties and uniform morphology of the composite naofibers were found at SWCNT concentration of ~2 wt % due to their stable and individual dispersion.

  1. Comparing the Intrinsic and Composite Resistivities of Carbon Nanofibers

    Science.gov (United States)

    Tibbetts, Gary; Kwag, Choongyong; Glasgow, Gerald; Lake, Max

    2003-03-01

    Carbon nanofibers have good electrical conductivity and sufficient length so that it is possible to fabricate electrically conducting composites with only small amounts of fiber. The intrinsic resistivities of several types of PYROGRAF fibers having differing surface preparation and morphology may be compared by squeezing the loose fibers in a die which allows in situ resistivity measurements. Intrinsic resistivities of loose nanofibers range from 0.03 to 3 Ohm cm, with longer fibers and those having coated surfaces exhibiting higher resistances. Resistivities of polypropylene composites fabricated with the same types of fibers are generally higher and range from 0.01 Ohm cm to over 1,000,000 Ohm cm. Long fibers lower composite resistivities, and composite resistivity correlates well with fiber length/diameter ratio. The innate differences between these two types of measurement will be discussed.

  2. Synthesis of microporous carbon nanofibers and nanotubes from conjugated polymer network and evaluation in electrochemical capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xinliang; Liang, Yanyu; Wu, Dongqing; Lieberwirth, Ingo; Muellen, Klaus [Max Planck Institute for Polymer Research, Mainz (Germany); Zhi, Linjie [National Center for Nanoscience and Technology of China Zhongguancun, Beijing (China); Thomas, Arne [Max Planck Institute for Colloids and Interfaces, Golm, Potsdam (Germany); Kolb, Ute [Institute of Physical Chemistry, Johannes Gutenberg Universitaet, Mainz (Germany)

    2009-07-10

    One-dimensional fibers and tubes are constructed through the oriented carbon-carbon cross-linking reactions towards rigid conjugated polymer networks. As the result, a template-free and one-step synthesis of CNTs and CNFs is achieved through a simple carbonization of the as-formed carbon-rich tubular and fiberlike polyphenylene precursors under argon. Microporous CNTs and CNFs with a surface area up to 900 m{sup 2} g{sup -1} are obtained, together with HR-TEM characterizations indicating the formation of intrinsic microporous structure in these rigid carbon-rich networks. The primary electrochemical experiments reveal their promising applications as advanced electrodes in electrochemical double-layered capacitor (EDLC). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  3. Designing an ultrathin silica layer for highly durable carbon nanofibers as the carbon support in polymer electrolyte fuel cells

    Science.gov (United States)

    Hwang, Sun-Mi; Park, Jae-Hyun; Lim, Seongyop; Jung, Doo-Hwan; Guim, Hwanuk; Yoon, Young-Gi; Yim, Sung-Dae; Kim, Tae-Young

    2014-09-01

    A critical issue for maintaining long-term applications of polymer electrolyte fuel cells (PEFCs) is the development of an innovative technique for the functionalization of a carbon support that preserves their exceptional electrical conductivity and robustly enriches their durability. Here, we report for the first time how the formation of a partially coated, ultrathin, hydrophobic silica layer around the surfaces of the carbon nanofiber (CNF) helps improve the durability of the CNF without decreasing the significant electrical conductivity of the virgin CNF. The synthesis involved the adsorption of polycarbomethylsilane (PS) on the CNF's sidewalls, followed by high temperature pyrolysis of PS, resulting in a highly durable, conductive carbon support in PEFCs. The Pt nanoparticles are in direct contact with the surface of the carbon in the empty spaces between unevenly coated silica layers, which are not deposited directly onto the silica layer. The presence of a Pt nanoparticle layer that was thicker than the silica layer would be a quite advantageous circumstance that provides contact with other neighboring CNFs without having a significant adverse effect that deeply damages the electrical conductivity of the neighboring CNF composites with the silica layer. Furthermore, the ultrathin, hydrophobic silica layer around the surfaces of the CNF provides great potential to reduce the presence of water molecules in the vicinity of the carbon supports and the &z.rad;OH radicals formed on the surface of the Pt catalyst. As a result, the CNF with a 5 wt% silica layer that we prepared has had extremely high initial performance and durability under severe carbon corrosion conditions, starting up with 974 mA cm-2 at 0.6 V and ending up with more than 58% of the initial performance (i.e., 569 mA cm-2 at 0.6 V) after a 1.6 V holding test for 6 h. The beginning-of-life and end-of-life performances based on the virgin CNF without the silica layer were 981 and 340 mA cm-2 at 0.6 V, respectively. The CNF having a silica layer had long-term durability which was superior to that of the virgin CNF.

  4. Designing an ultrathin silica layer for highly durable carbon nanofibers as the carbon support in polymer electrolyte fuel cells.

    Science.gov (United States)

    Hwang, Sun-Mi; Park, Jae-Hyun; Lim, Seongyop; Jung, Doo-Hwan; Guim, Hwanuk; Yoon, Young-Gi; Yim, Sung-Dae; Kim, Tae-Young

    2014-10-21

    A critical issue for maintaining long-term applications of polymer electrolyte fuel cells (PEFCs) is the development of an innovative technique for the functionalization of a carbon support that preserves their exceptional electrical conductivity and robustly enriches their durability. Here, we report for the first time how the formation of a partially coated, ultrathin, hydrophobic silica layer around the surfaces of the carbon nanofiber (CNF) helps improve the durability of the CNF without decreasing the significant electrical conductivity of the virgin CNF. The synthesis involved the adsorption of polycarbomethylsilane (PS) on the CNF's sidewalls, followed by high temperature pyrolysis of PS, resulting in a highly durable, conductive carbon support in PEFCs. The Pt nanoparticles are in direct contact with the surface of the carbon in the empty spaces between unevenly coated silica layers, which are not deposited directly onto the silica layer. The presence of a Pt nanoparticle layer that was thicker than the silica layer would be a quite advantageous circumstance that provides contact with other neighboring CNFs without having a significant adverse effect that deeply damages the electrical conductivity of the neighboring CNF composites with the silica layer. Furthermore, the ultrathin, hydrophobic silica layer around the surfaces of the CNF provides great potential to reduce the presence of water molecules in the vicinity of the carbon supports and the ?OH radicals formed on the surface of the Pt catalyst. As a result, the CNF with a 5 wt% silica layer that we prepared has had extremely high initial performance and durability under severe carbon corrosion conditions, starting up with 974 mA cm(-2) at 0.6 V and ending up with more than 58% of the initial performance (i.e., 569 mA cm(-2) at 0.6 V) after a 1.6 V holding test for 6 h. The beginning-of-life and end-of-life performances based on the virgin CNF without the silica layer were 981 and 340 mA cm(-2) at 0.6 V, respectively. The CNF having a silica layer had long-term durability which was superior to that of the virgin CNF. PMID:25196022

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

    International Nuclear Information System (INIS)

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

  6. Detection of ricin using a carbon nanofiber based biosensor.

    Science.gov (United States)

    Periyakaruppan, Adaikkappan; Arumugam, Prabhu U; Meyyappan, M; Koehne, Jessica E

    2011-10-15

    We report ricin detection using antibody and aptamer probes immobilized on a nanoelectrode array (NEA) consisting of vertically aligned carbon nanofibers (VACNFs). These biosensor chips are fabricated on a wafer scale using steps common in integrated circuit manufacturing. Electrochemical impedance spectroscopy is used to characterize the detection event and the results indicate that the electron transfer resistance changes significantly after the ricin protein binds to the probe. Further confirmation is obtained from evaluation of the electrode surface by atomic force microscopy which clearly shows a change in height from the bare electrode to the surface bound by the probe-protein. PMID:21852102

  7. Carbon nanofibers decorated with poly(furfuryl alcohol)-derived carbon nanoparticles and tetraethylorthosilicate-derived silica nanoparticles.

    Science.gov (United States)

    Zhang, Y; Yarin, A L

    2011-12-01

    The present paper introduces a novel method to functionalize nanofiber surfaces with carbon or silica nanoparticles by dip coating. This novel approach holds promise of significant benefits because dip coating of electrospun and carbonized nanofiber mats in poly(furfuryl alcohol) (abbreviated as PFA) is used to increase surface roughness by means of PFA-derived carbon nanoparticles produced at the fiber surface. Also, dip coating in tetraethylorthosilicate (abbreviated as TEOS) is shown to be an effective method for decorating carbon nanofibers with TEOS-derived silica nanoparticles at their surface. Furthermore, dip coating is an inexpensive technique which is easier to implement than the existing methods of nanofiber decoration with silica nanoparticles and results in a higher loading capacity. Carbon nanofiber mats with PFA- or TEOS-decorated surfaces hold promise of becoming the effective electrodes in fuel cells, Li-ion batteries and storage devices. PMID:21981576

  8. Health effects of exposure to carbon nanofibers: Systematic review, critical appraisal, meta analysis and research to practice perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Genaidy, Ash, E-mail: world_tek_inc@yahoo.com [University of Cincinnati, College of Engineering, Cincinnati, Ohio (United States); WorldTek Inc, Cincinnati (United States); Tolaymat, Thabet [U.S. EPA Office of Research and Development. Cincinnati, Ohio (United States); Sequeira, Reynold [University of Cincinnati, College of Engineering, Cincinnati, Ohio (United States); Rinder, Magda [WorldTek Inc, Cincinnati (United States); Dionysiou, Dion [University of Cincinnati, College of Engineering, Cincinnati, Ohio (United States)

    2009-06-01

    Background: Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and health consequences are qualitative in nature and do not employ an evidence-based assessment. Objective: This research deals with a systematic review, critical appraisal, and meta-analysis designed to examine the potential health effects associated with exposure to CNFs. The utilization of research findings into practice is also explored. Methods: Published articles were obtained from a search of electronic databases and bibliographies of identified articles. A critical appraisal was conducted using an 'Experimental Appraisal Instrument' developed in this study. The meta-analysis was established using statistical techniques with/without the incorporation of overall study quality. The likelihood of utilizing research findings into practice (i.e., from research to practice) was computed using a four-step algorithm based on the criteria of: strength of association, consistency among studies, temporality, biological gradient, type of experimental unit, type of CNF (single- and multi-wall nanotubes), CNF grade (commercial or altered), exposure dose, exposure duration, and support by analogy from the published literature. Results: Twenty-one experimental studies satisfied the inclusion criteria and were performed on human cells, experimental animal models and animal cells as experimental units. The methodological qualities of published studies ranged from 'very poor' to 'excellent', with 'overall study description' scoring 'good' and 'study execution' equal to 'moderate'. The random-effects model was applied in the meta-analysis calculations as heterogeneity was significant at the 10% for all outcomes reported. The mean standardized meta-estimates for the experimental groups were significantly lower than those for the control groups for cell viability and cell death, respectively. Incorporating the effect of overall study quality score widened the gap between the experimental and control groups. Assessment of research findings on the basis of the four-step algorithm revealed that the likelihood of the results to occur in practice is 'somewhat possible' at this time. That is, if exposure conditions to CNF in the reported studies are similar to those in nano-manufacturing plants, it is somewhat possible that CNFs alter the function of human cells resulting in loss of cell viability and cell death. Conclusions: Our findings suggest that it is 'somewhat possible' for the CNF to penetrate the human cells in the targeted organs and to cause cellular damage. Although the weight of evidence is not sufficient, it is advisable that actions be taken to ensure the protection of workers exposed to CNFs, that is, (a) engineering controls should be established to contain exposure to CNF, and (b) simultaneously rigorous personnel protective equipment should be planned to further minimize the risk of CNF exposure.

  9. Experimental study of mechanical and electrical properties of carbon nanofiber/epoxy composites

    International Nuclear Information System (INIS)

    Epoxy nanocomposites of different content of carbon nanofibers up to 1 wt.% have been fabricated under room temperature and refrigerated curing conditions. The composites were studied in terms of mechanical and electrical properties. Flexural modulus and hardness were found to increase significantly in refrigerated samples due to prevention of aggregates of nanofibers during cure condition. Increase and shifting in G-band by Raman spectra of these samples confirmed stress transfer and reinforcement between epoxy matrix and carbon nanofiber. Electrical conductivity improved by 3-6 orders after infusing carbon nanofibers in insulating epoxy. Room temperature samples acquired higher conductivity that was attributed to network formation by aggregates of nanofibers along the fiber alignment direction as revealed by electron microscopic studies.

  10. Binder-free Si nanoparticles@carbon nanofiber fabric as energy storage material

    International Nuclear Information System (INIS)

    A nonwoven nanofiber fabric with paper-like qualities composed of Si nanoparticles and carbon as binder-free anode electrode is reported. The nanofiber fabrics are prepared by convenient electrospinning technique, in which, the Si nanoparticles are uniformly confined in the carbon nanofibers. The high strength and flexibility of the nanofiber fabrics are beneficial for alleviating the structural deformation and facilitating ion transports throughout the whole composited electrodes. Due to the absence of binder, the less weight, higher energy density, and excellent electrical conductivity anodes can be attained. These traits make the composited nanofiber fabrics excellent used as a binder-free, mechanically flexible, high energy storage anode material in the next generation of rechargeable lithium ions batteries

  11. Electromagnetic Properties of Novel Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    WANG Gai-Hua, DAI Bo, MA Yong-Jun, REN Yong

    2013-04-01

    Full Text Available Carbonized bacterial cellulose (CBC with a three dimensional net-linked framework were synthesized from carbonized bacterial cellulose and investigated by X-ray diffraction, Raman spectrum and Transmission electron microscopy. The complex permittivity and permeability of CBC/paraffin wax composite with certain ratio of the composite were measured by vector network analysis in the frequency range of 0.1–18 GHz. It is found that the composite has high permittivity and dielectric loss, especially at the low frequency. The electromagnetic characteristics of the CBC/Fe3O4 complex absorbers synthesized by mixing a small quantity of CBC with Fe3O4 were also studied, aiming at improving the microwave absorbing properties of Fe3O4/Wax composite. When the sample’s thickness was 1.2 mm, the reflection loss reached a minimal value of –21 dB for CBC - Fe3O4/Wax and of –2 dB for Fe3O4/Wax as well.

  12. Pt/carbon nanofibers electrocatalysts for fuel cells. Effect of the support oxidizing treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zaragoza-Martin, F.; de Lecea, C. Salinas-Martinez [Departamento de Quimica Inorganica, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Sopena-Escario, D. [Fundacion CIDAUT, Parque tecnologico de Boecillo, E-47151 Boecillo (Valladolid) (Spain); Morallon, E. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)

    2007-09-27

    Different Pt-based electrocatalysts supported on carbon nanofibers and carbon black (Vulcan XC-72R) have been prepared using a polymer-mediated synthesis. The electrocatalysts have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and cyclic voltammetry. The effect of carbon nanofibers treatment with HNO{sub 3} solution on Pt particle size and electroactive area has been analyzed. Highly dispersed Pt with homogeneous particle size and an electroactive area around of 100 m{sup 2} g{sup -1} is obtained in raw carbon nanofibers. The oxidizing treatment of the carbon nanofibers produces agglomeration of the platinum nanoparticles and an electroactive area of 53 m{sup 2} g{sup -1}. Durability studies indicate a decrease of 14% in the electroactive area after 90 h at 1.2 V in 0.5 M H{sub 2}SO{sub 4} for platinum supported on raw carbon nanofibers and Vulcan XC-72R. The electrocatalyst supported on oxidized carbon nanofibers are stable under similar conditions. (author)

  13. Mechanical Damping Properties of Carbon Nanofiber Reinforced Composites

    Science.gov (United States)

    Varischetti, Joshua A.

    In this research an investigation of the damping enhancement achieved, utilizing carbon nano fibers (CNF) to epoxy resin is presented along with a corresponding model to predict damping performance. The addition of CNF fillers to the matrix allows for localized slip between the filler and the matrix on a nanoscale, wherein the matrix can de-bond from the CNFs, allowing the fillers to slip relative to the matrix; thereby, dissipating energy as frictional heat. Due to the nanoscale size of the filler, the specific surface area, of the CNF's, is very large when compared to traditional fiber reinforcement, this attribute allows small fractions of CNF fillers to have a large impact on the structural damping without any significant weight penalties. Moreover, once the composite returns to its undeformed configuration the interface between nano fillers and matrix will then re-establish the Van der Waals interactions that were broken to allow the slip. Thus, localized yet recoverable, frictional slip at the nano scale can be employed to significantly enhance strain dependent damping in composite structures wherein no permanent structural damage is evidenced. To better understand the damping response in CNF reinforced composites this study utilizes experimental and analytical approaches to develop modeling techniques that account for various fundamental attributes of high aspect ratio fillers, specifically the effect of filler aspect ratio, filler waviness, filler orientation relative to loading direction and the effect of multiple fillers on the damping performance and investigated in detail and corresponding modeling techniques are developed to address each of these factors in order to better predict the viscoelastic response of CNF reinforced composites. These models will be beneficial to address composite design while accounting for makeup, constituent properties, filler geometries, filler orientations, and their effective role in damping performance.

  14. Fabrication of porous carbon/Si composite nanofibers as high-capacity battery electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Liwen; Zhang, Xiangwu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, 2401 Research Drive/Box 8301, Raleigh, NC 27695-8301 (United States)

    2009-06-15

    Carbon/Si composite nanofibers with porous structures are prepared by electrospinning and subsequent carbonization processes. It is found that these porous composite nanofibers can be used as anode materials for rechargeable lithium-ion batteries (LIBs) without adding any binding or conducting additive. The resultant anodes exhibit good electrochemical performance; for example, a large discharge capacity of 1100 mAh g{sup -1} at a high current density of 200 mA g{sup -1}. (author)

  15. Vertically aligned carbon nanofiber nanoelectrode arrays: electrochemical etching and electrode reusability.

    Science.gov (United States)

    Gupta, Rakesh K; Meyyappan, M; Koehne, Jessica E

    2014-05-01

    Vertically aligned carbon nanofibers in the form of nanoelectrode arrays were grown on nine individual electrodes, arranged in a 3 × 3 array geometry, in a 2.5 cm(2) chip. Electrochemical etching of the carbon nanofibers was employed for electrode activation and enhancing the electrode kinetics. Here, we report the effects of electrochemical etching on the fiber height and electrochemical properties. Electrode regeneration by amide hydrolysis and electrochemical etching is also investigated for electrode reusability. PMID:25089188

  16. 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

  17. Vertically aligned carbon nanofiber electrode arrays for nucleic acid detection

    Science.gov (United States)

    Arumugam, Prabhu U.; Yu, Edmond; Riviere, Roger; Meyyappan, M.

    2010-10-01

    We present electrochemical detection of DNA targets that corresponds to Escherichia coli O157:H7 16S rRNA gene using a nanoelectrode array consisting of vertically aligned carbon nanofiber (VACNF) electrodes. Parylene C is used as gap filling 'matrix' material to avoid high temperature processing in electrode construction. This easy to deposit film of several micron heights provides a conformal coating between the high aspect ratio VACNFs with negligible pin-holes. The low background currents show the potential of this approach for ultra-sensitive detection. Consistent and reproducible electrochemical-signals are achieved using a simple electrode preparation. This simple, reliable and low-cost approach is a forward step in developing practical sensors for applications like pathogen detection, early cancer diagnosis and environmental monitoring.

  18. Electrospun vanadium pentoxide/carbon nanofiber composites for supercapacitor electrodes

    International Nuclear Information System (INIS)

    The vanadium pentoxide (V2O5)/carbon nanofiber composites (CNFCs) were prepared from polyacrylonitrile/V2O5 in N,N-dimethylformamide by a simple electrospinning method, and their electrochemical properties as supercapacitor electrodes were investigated. Different loadings of V2O5, the microstructures of the CNFCs (e.g., nanometer-size diameters, high specific surface areas, narrow pore size distributions, and tunable porosities) were changed, and the textural parameters significantly affected the electrochemical properties of the composites. The CNFC capacitors delivered the high specific capacitances of 150.0 F g?1 for the CNFCs in an aqueous, with promising energy densities of 18.8 Wh kg?1, over a power density range of 400–20,000 W kg?1. The CNFCs simultaneously exhibited excellent capacity retention.

  19. Nickel supported carbon nanofibers as an active and selective catalyst for the gas-phase hydrogenation of 2-tert-butylphenol.

    Science.gov (United States)

    Díaz, José Antonio; Díaz-Moreno, Rebeca; Silva, Luz Sánchez; Dorado, Fernando; Romero, Amaya; Valverde, José Luis

    2012-08-15

    Nickel supported fishbone carbon nanofibers (CNFs) have been prepared by vacuum impregnation (VI) and homogeneous deposition-precipitation (HDP) methods with different nickel loadings (ca. 5%, 9% and 12%) with the aim to study the influence of the metal incorporation method and the nickel loading in the catalytic activity of gas-phase hydrogenation of 2-tert-butylphenol (2-TBP). Moreover, the influence of the nature of the support was also studied by preparing nickel catalysts supported on other carbon (active carbon (AC) and graphite (G)) and non-carbonaceous materials (alumina (AL) and yttria-stabilized zirconia (YSZ)). Different techniques were employed to characterize both the supports and the final Ni catalysts: atomic absorption spectrometry, N(2) adsorption-desorption analysis, temperature-programed reduction (TPR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Catalytic results revealed that the nickel particle size and support properties affected directly to both the catalytic activity of hydrogenation of 2-TBP, and the rate of secondary reactions such as cis to trans isomerization and 2-tert-butylcyclohexanone (2-TBCN) hydrogenation. PMID:22682327

  20. 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.

  1. Ultrasound-assisted preparation of electrospun carbon nanofiber/graphene composite electrode for supercapacitors

    Science.gov (United States)

    Dong, Qiang; Wang, Gang; Hu, Han; Yang, Juan; Qian, Bingqing; Ling, Zheng; Qiu, Jieshan

    2013-12-01

    Electrospun carbon nanofiber/graphene (CNF/G) composites are prepared by in situ electrospinning polymeric nanofibers with simultaneous spraying graphene oxide, followed by heat treatment. The freestanding carbon nanofiber web acts as a framework for sustaining graphene, which helps to prevent the agglomeration of graphene and to provide a high conductivity for the efficient charge transfer to the pores. The as-obtained CNF/G composite exhibits a specific capacitance of 183 F g-1, which is approximately 1.6 times higher than that of the pristine CNF. The results have demonstrated that the high performance of the CNF/G composite is due to the novel structure and the synergic effect of graphene and the carbon nanofibers.

  2. Synthesis, chemistry and structure of boron-doped carbon nanotubes and nanofibers

    Science.gov (United States)

    Wang, Ling

    The objective of this project is to synthesize novel boron-rich carbon in the form of nanotubes and nanofibers and to determine the influence of high concentrations of boron on the sp2 carbon structure. Research efforts on the influence of high concentrations of boron on the sp 2 carbon structure have been undertaken through a combination of computational prediction and experimental investigation. A theoretical prediction regarding the boron influence on carbon nanotube structure is carried using molecular and quantum mechanical simulations. The influence of substitutional boron on strain, tube diameter, tube length and tube stability is discussed. A high boron doping (10-17 at.%) introduces disorder into the host sp2 carbon structure. Boron-doped carbon nanotubes and nanofibers have been synthesized by a catalytic CVD at 750-900°C from C6H6 and BCl 3. The deposition temperature and reactant ratio (BCl3/C 6H6) influence the microstructure and compositions of the resulting deposits significantly. The boron concentrations of the boron-doped carbon nanotubes and nanofibers are in the range of 5-18 at.% as measured by AES. The optimum temperature to obtain a high boron content sample is around 800°C. The crystal structures and microstructures of boron-doped carbon nanotubes and nanofibers are inhomogeneous. The boron doping into the carbon nanotubes and nanofibers is structure-related. The platelet stacked structure is always very well-ordered with very low boron concentration ( 8%. A disordered transition area between herringbone and tubular structure in a nanofiber of Sample I-1 is observed where the boron concentration is 16%, i.e., consistent with a composition of C6B. Mechanisms of boron-doped nanofiber growth are proposed that involve both surface diffusion and bulk diffusion process. Temperature is the governing factor that determines the process by which either surface diffusion or bulk diffusion dominates. Boron doping also influences the ordering of the carbon layer plane stacking.

  3. Electrodeposited MnOx/carbon nanofiber composites for use as anode materials in rechargeable lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhan; Ji, Liwen; Woodroof, Mariah D.; 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)

    2010-08-01

    Carbon nanofiber-supported MnOx composites were prepared by electrodepositing MnOx nanoparticles directly onto electrospun carbon nanofibers. The morphology and size of MnOx nanoparticles were controlled by the surface treatment of carbon nanofibers and the electrodeposition duration time. SEM, TEM/EDS, elemental analysis, and XRD were used to study the morphology and composition of MnOx on the nanofibers. The resultant MnOx/carbon nanofiber composites were used directly as the anode material in lithium half cells and their electrochemical performance was characterized. Results show that MnOx/carbon nanofiber composites prepared by different deposition durations have high reversible capacity, good capacity retention, and excellent structural integrity during cycling. (author)

  4. Ni-catalysed carbon nanotubes and nanofibers assemblies grown on TiN/Si(1 0 0) substrates using hot-filaments combined with d.c. plasma CVD

    Science.gov (United States)

    Fleaca, Claudiu Teodor; Le Normand, François

    2014-02-01

    Different carbon nanotubes or nanofibers (CNTs or CNFs) assemblies were obtained using Ni catalyst deposited by Pulsed Laser Deposition (PLD) on TiN/Si(1 0 0) substrate from a H2/C2H2 mixture using plasma emerging from triode configured electrodes with two pairs of intercalated incandescent filaments at 1 kPa and 700 °C. In the presence of a relative intense plasma (54 W power), a dense CNT carpet was grown. The TEM images revealed the presence of elongated yet contorted 10-15 nm diameter CNTs with encapsulated Ni particles at their tips. Using a low plasma power (8 W) in similar conditions and from the same catalyst, a different morphology resulted: few self-sustained long fibrils (diameter around 1 ?m) which are curved under the action of their own weight containing compacted CNTs/CNFs and (only in the confined zones near the lateral edges) 50-200 nm thick filaments presenting buds-like structures and Y-shape junctions.

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

    Science.gov (United States)

    2014-01-01

    In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm2 was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications. PMID:24387682

  6. Platinum nanocluster growth on vertically aligned carbon nanofiber arrays: Sputtering experiments and molecular dynamics simulations

    International Nuclear Information System (INIS)

    Highlights: ? Molecular dynamics simulation of platinum cluster growth on model carbon nanofibers. ? We compare modeled and experimental cluster growth. ? We determine sticking coefficient evolution among deposition time and type of nanofibers. ? We determine cluster size distribution on various model nanofibers. - Abstract: Sputtered platinum nanocluster growth on previously plasma enhanced chemical vapor deposition – PECVD – grown vertically aligned carbon nanofiber arrays is presented. Experimental cluster size distribution is shown to decrease from the CNF top to bottom, as observed by transmission electron microscopy. Molecular dynamics simulations are carried out for understanding early stages of Pt growth on model CNF arrays. Especially, sticking coefficients, concentration profiles along CNF wall, cluster size distributions are calculated. Simulated cluster size distribution are consistent with experimental finding. Sticking coefficient decreases against deposition time. The shape of the sticking curve reflects the nanocluster growth process.

  7. Platinum nanocluster growth on vertically aligned carbon nanofiber arrays: Sputtering experiments and molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Brault, Pascal, E-mail: Pascal.Brault@univ-orleans.fr [GREMI, UMR7344 CNRS-Universite d' Orleans BP 6744, 45067 Orleans Cedex 2 (France); Caillard, Amaeel [GREMI, UMR7344 CNRS-Universite d' Orleans BP 6744, 45067 Orleans Cedex 2 (France); Charles, Christine; Boswell, Rod W. [Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Graves, David B. [Department of Chemical and Biomolecular Engineering, 201 Gilman Hall 1462, University of California Berkeley, CA 94720-1462 (United States)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Molecular dynamics simulation of platinum cluster growth on model carbon nanofibers. Black-Right-Pointing-Pointer We compare modeled and experimental cluster growth. Black-Right-Pointing-Pointer We determine sticking coefficient evolution among deposition time and type of nanofibers. Black-Right-Pointing-Pointer We determine cluster size distribution on various model nanofibers. - Abstract: Sputtered platinum nanocluster growth on previously plasma enhanced chemical vapor deposition - PECVD - grown vertically aligned carbon nanofiber arrays is presented. Experimental cluster size distribution is shown to decrease from the CNF top to bottom, as observed by transmission electron microscopy. Molecular dynamics simulations are carried out for understanding early stages of Pt growth on model CNF arrays. Especially, sticking coefficients, concentration profiles along CNF wall, cluster size distributions are calculated. Simulated cluster size distribution are consistent with experimental finding. Sticking coefficient decreases against deposition time. The shape of the sticking curve reflects the nanocluster growth process.

  8. Development of radiation processing to functionalize carbon nanofiber to use in nanocomposite for industrial application

    International Nuclear Information System (INIS)

    Radiation can be used to modify and improve the properties of materials. Electron beam and gamma ray irradiation has potential application in modifying the structure of carbon fibers in order to produce useful defects in the graphite structure and create reactive sites. In this study was investigated a methodology for radiation grafting processing to modify carbon nanofiber surfaces by grafting acrylic acid. The samples were submitted to direct radiation process. Several parameters were changed such as acrylic acid concentration, radiation dose and percentage of inhibitor to achieve functionalization with higher percentage of oxygen functional groups on carbon nanofiber surface and better dispersion. The samples were characterized by X-ray Photoelectron Spectroscopy and the dispersion stability upon storage was visually investigated. Carbon nanofiber directed irradiated with electron beam and gamma ray in a solution of acrylic acid with 6% of inhibitor (FeSO4.7H2O) and irradiated at 100 kGy had an increase of 20% of oxygen content onto carbon nanofiber surface. The Auger D-parameter for the samples direct irradiated grafted ranged between 17.0-17.7 compared to 21.1-18.9 of the unirradiated ones. This indicated that these samples had less sp2 and more sp3 bonding characteristics than unirradiated samples. This can be an indication of C=C bond breaking leading to the formation of new sp3 carbon atoms on carbon nanofiber surface with oxygen functional groups grafted. The samples grafted presented a good and stable dispersion. (author)

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

    Science.gov (United States)

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

    2011-07-01

    Composite carbon-tin oxide (C-SnO(2)) nanofibers are prepared by two methods and evaluated as anodes in lithium-ion battery half cells. Such an approach complements the long cycle life of carbon with the high lithium storage capacity of tin oxide. In addition, the high surface-to-volume ratio of the nanofibers improves the accessibility for lithium intercalation as compared to graphite-based anodes, while eliminating the need for binders or conductive additives. The composite nanofibrous anodes have first discharge capacities of 788 mAh g(-1) at 50 mA g(-1) current density, which are greater than pure carbon nanofiber anodes, as well as the theoretical capacity of graphite (372 mAh g(-1)), the traditional anode material. In the first protocol to fabricate the C-SnO(2) composites, tin sulfate is directly incorporated within polyacrylonitrile (PAN) nanofibers by electrospinning. During a thermal treatment the tin salt is converted to tin oxide and the polymer is carbonized, yielding carbon-SnO(2) nanofibers. In the second approach, we soak the nanofiber mats in tin sulfate solutions prior to the final thermal treatment, thereby loading the outer surfaces with SnO(2) nanoparticles and raising the tin content from 1.9 to 8.6 wt %. Energy-dispersive spectroscopy and X-ray diffraction analyses confirm the formation of conversion of tin sulfate to tin oxide. Furthermore, analysis with Raman spectroscopy reveals that the additional salt soak treatment from the second fabrication approach increases in the disorder of the carbon structure, as compared to the first approach. We also discuss the performance of our C-SnO(2) compared with its theoretical capacity and other nanofiber electrode composites previously reported in the literature. PMID:21615138

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

    International Nuclear Information System (INIS)

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

  11. Preparation and Application of Carbon Nanofibers-supported Palladium Nanoparticles Catalysts Based on Electrospinning

    Directory of Open Access Journals (Sweden)

    GUO Li-Ping, BAI Jie, LIANG Hai-Ou, LI Chun-Ping, SUN Wei-Yan, MENG Qing-Run

    2014-08-01

    Full Text Available Carbon nanofibers-supported palladium nanoparticle catalysts were prepared by electrospinning, chemical reduction and the subsequent high temperature carbonization methods. The experiments were carried out to investigate the influence of different reducing agents (sodium borohydride, hydrazine hydrate and hydrogen gas on morphology of palladium nanoparticles and carbon nanofibers in detail. Catalysts were characterized by UV-Vis spectra, X-ray diffraction, fourier transform infrared spectrum, scanning electron microscope, field emission transmission electron microscope. Results show that the palladium nanoparticles are distributed uniformly on the carbon nanofibers with dimension of about 7 nm, and the catalyst is relatively flexible by using hydrogen gas as reducing agent. Then it was applied to the Heck coupling reaction to test catalytic properties and recyclability. Results indicate that the catalyst possesses excellent stability and recyclability.

  12. Carbonized Micro- and Nanostructures: Can Downsizing Really Help?

    Directory of Open Access Journals (Sweden)

    Mohammad Naraghi

    2014-05-01

    Full Text Available In this manuscript, we discuss relationships between morphology and mechanical strength of carbonized structures, obtained via pyrolysis of polymeric precursors, across multiple length scales, from carbon fibers (CFs with diameters of 5–10 µm to submicron thick carbon nanofibers (CNFs. Our research points to radial inhomogeneity, skin–core structure, as a size-dependent feature of polyacrylonitrile-based CFs. This inhomogeneity is a surface effect, caused by suppressed diffusion of oxygen and stabilization byproducts during stabilization through skin. Hence, reducing the precursor diameters from tens of microns to submicron appears as an effective strategy to develop homogeneous carbonized structures. Our research establishes the significance of this downsizing in developing lightweight structural materials by comparing intrinsic strength of radially inhomogeneous CFs with that of radially homogeneous CNF. While experimental studies on the strength of CNFs have targeted randomly oriented turbostratic domains, via continuum modeling, we have estimated that strength of CNFs can reach 14 GPa, when the basal planes of graphitic domains are parallel to nanofiber axis. The CNFs in our model are treated as composites of amorphous carbon (matrix, reinforced with turbostratic domains, and their strength is predicted using Tsai–Hill criterion. The model was calibrated with existing experimental data.

  13. Characteristics of supercapacitor electrodes of PBI-based carbon nanofiber web prepared by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Chan Kim; Park, Sang Hee; Lee, Wan Jin; Yang, Kep Seung [Chonnam National Univ., Gwangju (Korea). Faculty of Applied Chemical Engineering

    2004-11-30

    Polybenzimidazol (PBI) solutions of dimethyl acetamide (DMAc) were electrospun to be webs consisting of 250-nm ultra-fine fibers. The webs were carbonized, activated by steam, and resulted in activated carbon nanofibers (ACNFs). The average pore diameter and specific surface areas were 0.64-0.66 nm and 500-1220 m{sup 2}/g, respectively. The specific capacitance from the activated carbon nanofiber ranged from 125 to 178 F/g, depending on the activation temperature. The capacitance of the electrical double layer capacitor was strongly dependent on the specific surface area, micro pore volume, and resistivity of the samples. (Author)

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

    International Nuclear Information System (INIS)

    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.

  15. 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.

  16. 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.

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

    OpenAIRE

    Lei Liu; Pingge He; Kechao Zhou; Tengfei Chen

    2013-01-01

    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...

  18. Electrical properties of isotactic polypropylene loaded with carbon nanofibers

    Science.gov (United States)

    Chipara, Mircea; Ciurea, Magdalena L.; Lozano, Karen; Aldica, Gheorghe V.; Chipara, Dorina M.; Popa, Stelian; Stavarache, Ionel

    2013-03-01

    Nanocomposites have been obtained by dispersing vapor grown carbon nanofibers (VGCNF) within isotactic polypropylene (iPP) via melt mixing. VGCNFs were purified and disentangled before blending with iPP. The mixing was performed by using HAAKE Rheomix, at 180 ^oC and 65 rpm for 9 minutes followed by an additional mixing at 90 rpm for 5 minutes (same temperature). The electrical properties of nanocomposites loaded with various amounts of VGCNFs (0%, 1%, 2.5%, 5%, 7.5%, 10%, 15%, and 20% wt.) have been investigated. DC electrical measurements revealed a percolation threshold at about 12 % wt. VGCNFs. The DC electrical characteristics of the nanocomposites located above the percolation threshold were investigated in detail, in a wide temperature range starting from 20 K up to about 750 K. The investigations revealed small changes of the DC conductivity within the glass and melting transition range of the polymeric matrix. The dominant charge transport mechanism below the glass transition temperature as well as between the glass and melting transition temperature is the variable range hopping. Above the melting temperature an Arrhenius like dependence of the DC conductivity was noticed.

  19. Manipulation of bacteriophages with dielectrophoresis on carbon nanofiber nanoelectrode arrays.

    Science.gov (United States)

    Madiyar, Foram R; Syed, Lateef U; Culbertson, Christopher T; Li, Jun

    2013-04-01

    This work describes efficient manipulation of bacteriophage virus particles using a nanostructured DEP device. The nonuniform electric field for DEP is created by utilizing a nanoelectrode array (NEA) made of vertically aligned carbon nanofibers versus a macroscopic indium tin oxide electrode in a "points-and-lid" configuration integrated in a microfluidic channel. The capture of the virus particles has been systematically investigated versus the flow velocity, sinusoidal AC frequency, peak-to-peak voltage, and virus concentration. The DEP capture at all conditions is reversible and the captured virus particles are released immediately when the voltage is turned off. At the low virus concentration (8.9 × 10(4) pfu/mL), the DEP capture efficiency up to 60% can be obtained. The virus particles are individually captured at isolated nanoelectrode tips and accumulate linearly with time. Due to the comparable size, it is more effective to capture virus particles than larger bacterial cells with such NEA-based DEP devices. This technique can be potentially utilized as a fast sample preparation module in a microfluidic chip to capture, separate, and concentrate viruses and other biological particles in small volumes of dilute solutions in a portable detection system for field applications. PMID:23348683

  20. Patterned growth of individual and multiple vertically aligned carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Merkulov, V. I. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Lowndes, D. H. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wei, Y. Y. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Eres, G. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Voelkl, E. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2000-06-12

    The results of studies of patterned growth of vertically aligned carbon nanofibers (VACNFs) prepared by plasma-enhanced chemical vapor deposition are reported. Nickel (Ni) dots of various diameters and Ni lines with variable widths and shapes were fabricated using electron beam lithography and evaporation, and served for catalytic growth of VACNFs whose structure was determined by high resolution transmission electron microscopy. It is found that upon plasma pre-etching and heating up to 600-700 degree sign C, thin films of Ni break into droplets which initiate the growth of VACNFs. Above a critical dot size multiple droplets are formed, and consequently multiple VACNFs grow from a single evaporated dot. For dot sizes smaller than the critical size only one droplet is formed, resulting in a single VACNF. In the case of a patterned line, the growth mechanism is similar to that from a dot. VACNFs grow along the line, and above a critical linewidth multiple VACNFs are produced across the line. The mechanism of the formation of single and multiple catalyst droplets and subsequently of VACNFs is discussed. (c) 2000 American Institute of Physics.

  1. Silicotungstic acid stabilized Pt-Ru nanoparticles supported on carbon nanofibers electrodes for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Maiyalagan, T. [Department of Chemistry, School of Science and Humanities, VIT University, Vellore 632014 (India)

    2009-04-15

    Silicotungstic acid stabilized Pt-Ru nanoparticles supported on Functionalized Carbon Nanofibers have been prepared by a microwave-assisted polyol process. The samples were characterized by XRD, SEM and TEM analysis. The electro-catalytic activities of the prepared composites (20% Pt-Ru/STA-CNF) were examined by using Cyclic Voltammetry (CV) for oxidation of methanol. The electro-catalytic activity of the carbon nanofiber based composite (20% Pt-Ru/STA-CNF) electrode for methanol oxidation showed better performance than that of commercially available Johnson Mathey 20% Pt-Ru/C and 20% Pt-Ru/STA-C catalyst. The results imply that carbon nanofiber based STA composite electrodes are excellent potential candidates for application in direct methanol fuel cells. (author)

  2. Carbon Nanotubes/Nanofibers by Plasma Enhanced Chemical Vapour Deposition

    Science.gov (United States)

    Teo, K. B. K.; Hash, D. B.; Bell, M. S.; Chhowalla, M.; Cruden, B. A.; Amaratunga, G. A. J.; Meyyappan, M.; Milne, W. I.

    2005-01-01

    Plasma enhanced chemical vapour deposition (PECVD) has been recently used for the production of vertically aligned carbon nanotubedfibers (CN) directly on substrates. These structures are potentially important technologically as electron field emitters (e.g. microguns, microwave amplifiers, displays), nanoelectrodes for sensors, filter media, superhydrophobic surfaces and thermal interface materials for microelectronics. A parametric study on the growth of CN grown by glow discharge dc-PECVD is presented. In this technique, a substrate containing thin film Ni catalyst is exposed to C2H2 and NH3 gases at 700 C. Without plasma, this process is essentially thermal CVD which produces curly spaghetti-like CN as seen in Fig. 1 (a). With the plasma generated by biasing the substrate at -6OOV, we observed that the CN align vertically during growth as shown in Fig. l(b), and that the magnitude of the applied substrate bias affects the degree of alignment. The thickness of the thin film Ni catalyst was found to determine the average diameter and inversely the length of the CN. The yield and density of the CN were controlled by the use of different diffusion barrier materials under the Ni catalyst. Patterned CN growth [Fig. l(c)], with la variation in CN diameter of 4.1% and 6.3% respectively, is achieved by lithographically defining the Ni thin film prior to growth. The shape of the structures could be varied from very straight nanotube-like to conical tip-like nanofibers by increasing the ratio of C2H2 in the gas flow. Due to the plasma decomposition of C2H2, amorphous carbon (a-C) is an undesirable byproduct which could coat the substrate during CN growth. Using a combination of depth profiled Auger electron spectroscopy to study the substrate and in-situ mass spectroscopy to examine gas phase neutrals and ions, the optimal conditions for a-C free growth of CN is determined.

  3. Graphenized carbon nanofiber: a novel light-trapping and conductive material to achieve an efficiency breakthrough in silicon solar cells.

    Science.gov (United States)

    Chen, Xi; Jia, Baohua; Cai, Boyuan; Fang, Jia; Chen, Ze; Zhang, Xiaodan; Zhao, Ying; Gu, Min

    2015-02-01

    An innovative 1D material--graphenized carbon nanofiber--is designed and synthesized. The nanofiber exhibits superior light-scattering properties, ultralow absorption loss, and high electrical conductivity, and enables a wide range of applications. Simply integrating the nanofibers with the state-of-the-art silicon solar cells leads to a leaping efficiency boost of 3.8%, almost five times higher than the current world record. PMID:25363355

  4. Vertically aligned carbon nanofibers and related structures: Controlled synthesis and directed assembly

    International Nuclear Information System (INIS)

    The controlled synthesis of materials by methods that permit their assembly into functional nanoscale structures lies at the crux of the emerging field of nanotechnology. Although only one of several materials families is of interest, carbon-based nanostructured materials continue to attract a disproportionate share of research effort, in part because of their wide-ranging properties. Additionally, developments of the past decade in the controlled synthesis of carbon nanotubes and nanofibers have opened additional possibilities for their use as functional elements in numerous applications. Vertically aligned carbon nanofibers (VACNFs) are a subclass of carbon nanostructured materials that can be produced with a high degree of control using catalytic plasma-enhanced chemical-vapor deposition (C-PECVD). Using C-PECVD the location, diameter, length, shape, chemical composition, and orientation can be controlled during VACNF synthesis. Here we review the CVD and PECVD systems, growth control mechanisms, catalyst preparation, resultant carbon nanostructures, and VACNF properties. This is followed by a review of many of the application areas for carbon nanotubes and nanofibers including electron field-emission sources, electrochemical probes, functionalized sensor elements, scanning probe microscopy tips, nanoelectromechanical systems (NEMS), hydrogen and charge storage, and catalyst support. We end by noting gaps in the understanding of VACNF growth mechanisms and the chalng of VACNF growth mechanisms and the challenges remaining in the development of methods for an even more comprehensive control of the carbon nanofiber synthesis process

  5. 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.

  6. Strong and stiff aramid nanofiber/carbon nanotube nanocomposites.

    Science.gov (United States)

    Zhu, Jiaqi; Cao, Wenxin; Yue, Mingli; Hou, Ying; Han, Jiecai; Yang, Ming

    2015-03-24

    Small but strong carbon nanotubes (CNTs) are fillers of choice for composite reinforcement owing to their extraordinary modulus and strength. However, the mechanical properties of the nanocomposites are still much below those for mechanical parameters of individual nanotubes. The gap between the expectation and experimental results arises not only from imperfect dispersion and poor load transfer but also from the unavailability of strong polymers that can be effectively utilized within the composites of nanotubes. Aramid nanofibers (ANFs) with analogous morphological features to nanotubes represent a potential choice to complement nanotubes given their intrinsic high mechanical performance and the dispersible nature, which enables solvent-based processing methods. In this work, we showed that composite films made from ANFs and multiwalled CNTs (MWCNTs) by vacuum-assisted flocculation and vacuum-assisted layer-by-layer assembly exhibited high ultimate strength of up to 383 MPa and Young's modulus (stiffness) of up to 35 GPa, which represent the highest values among all the reported random CNT nanocomposites. Detailed studies using different imaging and spectroscopic characterizations suggested that the multiple interfacial interactions between nanotubes and ANFs including hydrogen bonding and ?-? stacking are likely the key parameters responsible for the observed mechanical improvement. Importantly, our studies further revealed the attractive thermomechanical characteristics of these nanocomposites with high thermal stability (up to 520 °C) and ultralow coefficients of thermal expansion (2-6 ppm·K(-1)). Our results indicated that ANFs are promising nanoscale building blocks for functional ultrastrong and stiff materials potentially extendable to nanocomposites based on other nanoscale fillers. PMID:25712334

  7. Electrochemical enzymatic biosensors using carbon nanofiber nanoelectrode arrays

    Science.gov (United States)

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

    2012-10-01

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

  8. 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.

  9. Electrochemical behavior of TiO2/carbon dual nanofibers

    International Nuclear Information System (INIS)

    The charge transfer processes are favored in dual nanofibers composed by TiO2Rutile-Csemigraphitic/Csemigraphitic over other systems such as TiO2Anatase and Rutile-Camorphous/Camorphous and TiO2Rutile-Camorphous, dual and single nanofibers respectively. The study of electrochemical impedance spectroscopy (EIS) shows that the net of nanofibers presented a charge transfer resistance value (Rct) of 3.15 ?. The increased ability of these materials to favor the diffusion of electroactive species in individual nanofibers is that the junction between the n-type semiconductor TiO2 and the semigraphitic material can be of the ohmic kind. Moreover, this observation was supported by cyclic voltammetry (CV) and electrical conductivity studies by two-probe method. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) confirmed the continuity and duality in the morphology of these materials. The effect of heat treatment on crystallinity was evident in the results obtained from the X-Ray Diffraction (XRD) and Selected Area Electron Diffraction (SAED) studies. Due to the electrochemical performance and morphological features of TiO2Rutile-Csemigraphitic/Csemigraphitic dual nanofibers; this novel nanostructured material can be regarded as an excellent candidate for applications such as a base material for electronic devices, photocatalysis, among other similar technologies

  10. 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. PMID:25510199

  11. 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

  12. Controlling the optimum surfactants concentrations for dispersing carbon nanofibers in aqueous solution

    Science.gov (United States)

    Wang, Bao-Min; Yuan, Zhang; Guo, Zhi-Qiang; Ma, Hai-Nan; Lai, Chuan Fook

    2013-12-01

    As a new nano-scale functional material, it is necessary to achieve a uniform distribution in the composites for gaining the CNFs' excellent reinforcing effect. In this paper, CNFs were purified by the method of high temperature annealing treatment. Six surfactants, methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), sodium dodecyl sulfate (SDS), dodecylamine (DDA), N, N-dimethyl formamide (DMF) and cetyltrimethyl ammonium bromide (CTAB) were used individually and combinatorially in a certain concentration to disperse the CNFs in aqueous solution. To achieve a good dispersion of the CNFs, a method utilizing ultrasonic processing was employed. The CNFs treated by the method of high temperature annealing treatment were characterized by differential thermal analysis (DTA) and thermogravimetry analysis (TGA), and the ultrasonication-driven dispersion of CNFs in aqueous solutions were monitored by UVvis spectroscopy and transmission electron microscopy (TEM). The experiments reveal that the method of high temperature annealing treatment purified the CNFs and the maximum achievable dispersion of CNFs corresponds to the maximum UV absorbance of the solution. All results show that the surfactants mixture of MC and SDS in a certain concentration of 0.4 and 2.0 g/L has the maximum dispersion effect on CNFs in aqueous solution, the optimum concentration ratio of MC, SDS, and CNFs was 2: 10: 1.

  13. 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...

  14. DC Plasma Synthesis of Vertically Aligned Carbon Nanofibers for Biointerfacing

    Science.gov (United States)

    Pearce, Ryan Christopher

    Vertically aligned carbon nanofibers (VACNFs) are a class of materials whose nanoscale dimensions and physical properties makes them uniquely suitable as functional elements in many applications for biodetection and biointerfacing on a cellular level. Control of VACNF synthesis by catalytic plasma enhanced chemical vapor deposition (PECVD) presents many challenges in integration into devices and structures designed for biointerfacing, such as transparent or flexible substrates. This dissertation addresses ways to overcome many of these issues in addition to deepening the fundamental understanding of nano-synthesis in catalytic PECVD. First, a survey of the field of VACNF synthesis and biointerfacing is presented, identifying the present challenges and greatest experimental applications. It is followed by experimental observations that elucidate the underlying mechanism to fiber alignment during synthesis, a critical step for deterministic control of fiber growth. Using a grid of electrodes patterned by photolithography on an insulating substrate, it was found that the alignment of the fibers is controlled by the anisotropic etching provided by ions during dc-PECVD synthesis. The VACNFs that have been utilized for many cellular interfacing experiments have unique mechanical and fluorescent properties due to a SiNx coating. The mechanism for SiNx deposition to VACNF sidewalls during synthesis is explored in addition to a detailed study of the optical properties of the coating. To explain the optical properties of this coating it is proposed that the source of photoluminescence for the SiNx coated VACNFs is quantum confinement effects due to the presence of silicon nanoclusters embedded in a Si3N4 matrix. These luminescent fibers have proven useful as registry markers in cell impalefection studies. To realize VACNF arrays used as an inflatable angioplasty balloon with embedded fibers to deliver drugs across the blood-brain barrier, a method for transferring fibers to flexible polydimethylesiloxane (PDMS) is presented. A process has been developed that involves synthesizing fibers on aluminum, followed by spin coating a thin layer of PDMS and then dissolving the underlying aluminum with KOH. Finally, a method of fiber synthesis using just air and acetone as the process gases is presented, enabling the possibility of inatmosphere, large scale VACNF synthesis. It is envisioned that these advancements should assist the viability of large scale VACNF related technologies and will help to bridge the gap between experimental applications and industrial adoption.

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

    OpenAIRE

    Andersen, Shuang Ma; Borghei, Maryam; Lund, Peter; Elina, Yli-rantala; Pasanen, Antti; Kauppinen, Esko; Ruiz, Virginia; Kauranen, Pertti; Skou, Eivind Morten

    2013-01-01

    Durability issues have recently been given much attention in Proton Exchange Membrane Fuel Cell (PEMFC) research. It gives fundamental definition for cell life time, capital cost, system stability and technique reliability. Loss of catalyst surface area due to corrosion of supporting material (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...

  16. Decomposition of Fe5C2 catalyst particles in carbon nanofibers during TEM observation

    Directory of Open Access Journals (Sweden)

    Vladimir D Blank, Boris A Kulnitskiy, Igor A Perezhogin, Yuriy L Alshevskiy and Nikita V Kazennov

    2009-01-01

    Full Text Available The effect of an electron beam on nanoparticles of two Fe carbide catalysts inside a carbon nanofiber was investigated in a transmission electron microscope. Electron beam exposure does not result in significant changes for cementite (?-Fe3C. However, for Hägg carbide nanoparticles (?-Fe5C2, explosive decay is observed after exposure for 5–10 s. This produces small particles of cementite and ?-Fe, each covered with a multilayer carbon shell, and significantly modifies the carbon-fiber structure. It is considered that the decomposition of Hägg carbide is mostly due to the damage induced by high-energy electron collisions with the crystal lattice, accompanied by the heating of the particle and by mechanical stress provided by the carbon layers of the nanofiber.

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

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2013-08-01

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

  18. 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

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

    OpenAIRE

    Lichao Feng; Ning Xie; Jing Zhong

    2014-01-01

    Carbon nanofiber (CNF), as one of the most important members of carbon fibers, has been investigated in both fundamental scientific research and practical applications. CNF composites are able to be applied as promising materials in many fields, such as electrical devices, electrode materials for batteries and supercapacitors and as sensors. In these applications, the electrical conductivity is always the first priority need to be considered. In fact, the electrical property of CNF composites...

  20. Development of Electro-Mechanical Spinning for Controlled Deposition of Carbon Nanofibers

    Science.gov (United States)

    Canton, Giulia

    In the past few decades the fields of nanotechnology and miniaturized devices had an exponentially growth of interest in academic and research environment, leading to breakthroughs discoveries that are envisioned to have a profound impact on our economy and society in the near future. Recently, the focus is moving toward the development of technologies that enable the production of micro- /nano-devices on a larger scale and at lower costs. Among the different micro- /nano-devices manufacturing challenges, in this dissertation the aim is to reliably fabricate suspend carbon micro- /nano-fibers between two carbon electrode walls in a way that can be mass produced at relatively low cost. The first part of this thesis provides an in depth overview of current methods used for the fabrication of carbon based micro devices (C-MEMS) and of electrospinning, a manufacturing technology that emerges as a simple and inexpensive approach to produce nanofibers. Electro-Mechanical Spinning (EMS) has been developed from electrospinning and optimized for the production of suspended carbon nanofibers, aiming to achieve greater deposition control at the single nanofiber level, while maintaining the low cost of electrospinning. After the successful development of EMS, the so fabricated carbon micro- /nano-fibers have been characterized, first from the electrical point of view, then from the mechanical one. The electrical characterization involves conductivity measurements of fibers with respect of different and controllable manufacturing processes steps. Variations of those manufacturing parameters have been proven to be capable of tailoring the carbon structure and, therefore, the conductivity of the fibers within a desired range. Further investigation regarding the electrical properties was also conducted to prevent (or control) current induced fiber breakdown. Finally, the Young's modulus of those fibers was investigated and observed to be dependent on the fibers thickness. Similarly to conductivity, variations in Young's modulus are also related to formation of a different carbon structure when fibers diameter is below certain values. In conclusion, appropriate combinations of EMS and C-MEMS processes were proven to be capable of fabricating controllable suspended carbon nanofibers with tuned conductivity and Young's modulus properties.

  1. Carbon nano-fiber growth on the anode during hydrogen DC arc-discharge

    Science.gov (United States)

    Kajiura, Hisashi; Huang, Houjin; Tsutsui, Shigemitsu; Murakami, Yousuke; Miyakoshi, Mitsuaki

    2003-03-01

    A carbon nano-fiber with a diameter of 25-100 nm and 98.4 percent purity was produced on the heated anode surface in hydrogen DC arc-discharge [1]. Hydrogen arc plasma was generated between the graphite cathode and the carbon/metal composite anode (Fe/Co/Ni/FeS). X-ray diffraction analysis revealed that the carbon nano-fiber had a turbostratic structure with a (002) interlayer spacing of 0.346nm. Three types of nano-structures were observed using transmission electron microscopy, (1) those with a bamboo structure, (2) with a hollow core, and (3) without a hollow core. The formation of the nano-fiber was initiated by arc-generated metal particles with a diameter of 5-75 nm, and carbon for further growth was supplied by the decomposition of polycyclic aromatic hydrocarbons that were created by interaction between arc-generated carbon clusters and hydrogen atoms. The nano-structure of the fiber is thought to depend on the size and morphology of the catalytic metal particles. [1] H. Kajiura et al., Carbon 40(2002)2423.

  2. Ni K-Edge XANES Analyses of Residual Ni Catalyst in Carbon Nanofiber Using Full Multiple Scattering Theory

    International Nuclear Information System (INIS)

    Residual Ni species after Ni removal treatment of carbon nanofibers have been investigated by use of XAFS analyses. Most of the Ni impurities are in Ni monomer which is located on defects in carbon nanofibers. The XAFS analyses combined with the multiple scattering theory give useful information on nano-structures of small amount species. Molecular orbital calculation also support the results from the XAFS analyses

  3. 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.

  4. Fe3O4/carbon composite nanofiber absorber with enhanced microwave absorption performance

    International Nuclear Information System (INIS)

    Highlights: ? PAN/AAI/DMF solutions for electrospinning. ? Fe3O4/carbon composite nanofibers as microwave absorbers. ? Microwave absorption performance has been much enhanced than pure carbon naonfibers. ? Microwave absorption mechanisms have been discussed as a key point. - Abstract: Fe3O4/carbon composite nanofibers were prepared by electrospinning polyacrylonitrile (PAN)/acetyl acetone iron (AAI)/dimethyl formamide (DMF) solution, followed by stabilization and carbonization. SEM and TEM observations reveal that the fibers are lengthy and uniform, and are loaded with well-distributed Fe3O4 nanoparticles, which are evidenced by XRD. Electrical and magnetic properties of the samples were studied to show the effect of enhancement of electrical conductivity and magnetic hysteresis performance. Finally, the permittivity and permeability parameters were measured by a vector network analyzer, and the reflectivity loss was calculated based on Transmission Line Theory. Results show that Fe3O4/C composite nanofibers exhibit enhanced properties of microwave absorption as compared to those of pure carbon nanofibers by: decreasing reflectivity loss values; widening absorption width and improving performance in low frequency (2–5 GHz) absorption. Absorption properties can be tuned by changing AAI content, carbonization temperature, composite fiber/paraffin ratio and coating thicknessffin ratio and coating thickness. It is shown that with coating thickness of 5 mm and fiber/paraffin ratio of 5 wt.%, the bandwidth for reflection loss under ?5 dB can reach a maximum of 12–13 GHz in the range of 2–18 GHz, accompanying with a minimum reflection loss of ?40 to ?45 dB, and preferred low frequency band absorption can also be obtained. The mechanisms for the enhanced absorption performance were briefly discussed. It is supposed that this kind of composite material is promising for resolving the problems of weak absorption in the low frequency range and narrow bandwidth absorption.

  5. LiCoPO4—3D carbon nanofiber composites as possible cathode materials for high voltage applications

    International Nuclear Information System (INIS)

    Electrospun and carbonized 3D nanofiber mats coated with olivine structured lithium cobalt phosphate (LiCoPO4) were formed by a Pechini-assisted sol–gel process as cathode material for lithium ion batteries. 3D nonwoven nanofibers were soaked in aqueous solution containing lithium, cobalt salts and phosphates at 80 °C for 2 h. Then, the composites were dried and annealed at 730 °C for 2 to 12 h in nitrogen atmosphere. Crystalline deposits were uniformly distributed on the carbon nanofiber surface. The “loading” of the cathode material on the 3D carbon nanofiber composites reached 300 wt%. The electrochemical measurements revealed the discharge specific capacity (measured at a discharge rate of 0.1 C and room temperature) reaching a maximum value of 46 mAh g?1 after annealing time t = 5 h

  6. Electrospun polyvinyl alcohol/carbon dioxide modified polyethyleneimine composite nanofiber scaffolds.

    Science.gov (United States)

    Wu, Han-Bing; Bremner, David H; Nie, Hua-Li; Quan, Jing; Zhu, Li-Min

    2015-05-01

    A novel biocompatible polyvinyl alcohol/carbon dioxide modified polyethyleneimine (PVA/PEI-CO2) composite nanofiber was fabricated by a green and facile protocol, which reduces the cytotoxicity of PEI through the surface modification of the PEI with CO2. The (13)C NMR spectrum, elemental analysis, and TGA show that CO2 has been incorporated in the PEI surface resulting in a relatively stable structure. The resulting PVA/PEI-CO2 composite nanofibers have been characterized by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), contact angle, and scanning electron microscopy (SEM). The results show that the average diameters of the nanofibers range from 265?±?53?nm to 423?±?80?nm. The cytotoxicity of PVA/PEI-CO2 composite nanofibers was assessed by cytotoxicity evaluation using the growth and cell proliferation of normal mice Schwann cells. SEM and the MTT assay demonstrated the promotion of cell growth and proliferation on the PVA/PEI-CO2 composite scaffold. It suggests that PEI-CO2 can have tremendous potential applications in biological material research. PMID:25540321

  7. 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.

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

    OpenAIRE

    Dong Liu; Yang Liu; Haoqing Hou; Tianyan You

    2010-01-01

    A novel sonochemical process, using hydrogen peroxide in a laboratory ultrasonic bath, was employed to pretreat the carbon nanofiber (CNF) for creating oxygen-rich groups on the surface of CNF. After the sonochemical process, the CNF showed good hydrophilicity and high electrochemical activity. Compared to normal pretreatment process, this sonochemical process is timesaving and effective for dispersion and functionalization of CNF. The resulting CNF showed high catalytic activity toward the o...

  9. 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...

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

    OpenAIRE

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

    2013-01-01

    We report an electrochemical method for measuring the activity of proteases using nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). The VACNFs of ~150 nm in diameter and 3 to 5 ?m in length were grown on conductive substrates and encapsulated in SiO2 matrix. After polishing and plasma etching, controlled VACNF tips are exposed to form an embedded VACNF NEA. Two types of tetrapeptides specific to cancer-mediated proteases legumain and cathepsin B are c...

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

    OpenAIRE

    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-tim...

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

    OpenAIRE

    Ruta, Marina

    2008-01-01

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

  13. Synthesis of carbon nanofibers by catalytic pyrolysis of ethylene and methane at hydrides of lanthanum-nickel intermetallic compounds

    International Nuclear Information System (INIS)

    Carbon nanofibers were synthesized by pyrolysis of ethylene and methane on hydrides of LaNinHx (n=2, 3, 5; x=0.1-4) intermetallic compounds. Effect of parameters of the synthesis: temperature and relation of gases in the Ar:H2:C2H4 (CH4) mixture on the structure of formed nanofibers is studied. Used hydrides of nickel intermetallic compounds are more appropriate catalytic systems than metallic nickel

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

    OpenAIRE

    Emel Yildiz; Matthew Matzek; William Fox; Khalid Lafdi

    2008-01-01

    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 (the...

  15. Synthesis of palladium nanoparticles decorated helical carbon nanofiber as highly active anodic catalyst for direct formic acid fuel cells

    International Nuclear Information System (INIS)

    Highlights: ? We present a single metal synthesis of highly active catalysts based on Pd-helical carbon fibers. ? Our catalyst material show better performance than Pd-decorated multi-walled nanotubes. ? Formic acid fuel cell tests with Pd-helical carbon nanofibers as anode show high power densities. ? Helical carbon nanofibers have several good properties for electrochemical applications. - Abstract: We present a single metal approach to produce highly active catalyst materials based on Pd-decorated helical carbon nanofibers. Helical carbon fibers are synthesized by a chemical vapor deposition process on a C60 supported Pd catalyst and the obtained fibers are functionalized by H2O2 followed by a decoration with Pd nanoparticles. Although transmission electron microscopy images show that the decoration is relatively inhomogeneous the electrocatalytic activity for formic acid oxidation is very high. Cyclic voltammetry measurements (CV) show that the generated current peak value for Pd-decorated helical carbon nanofibers is 300 mA/mgPd for a scan rate of 10 mV/s. This is significantly higher than the corresponding value of a reference sample of multiwalled carbon nanotubes decorated with Pd nanoparticles by the same process. Fuel cell tests for our Pd-decorated helical carbon nanofibers also displayed a high power density, although not as superior to Pd-decorated multiwalled nanotubes as measured by CV. Our results shoas measured by CV. Our results show that helical carbon nanofibers have several good properties, such as a rigid anchoring of catalyst nanoparticles and a suitable structure for creating functionalization defects which make them an interesting candidate for electrochemical applications.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-08-01

    Lanthanum strontium manganite (La(0.8)Sr(0.2)MnO(3), LSM) nanofibers have been synthesized by the electrospinning method. The electrospun nanofibers are intact without morphological and structural changes after annealing at 1050?°C. The LSM nanofibers are employed as the sensing electrode of an electrochemical sensor with yttria-stabilized zirconia (YSZ) electrolyte for carbon monoxide detection at high temperatures over 500?°C. The electrospun nanofibers form a porous network electrode, which provides a continuous pathway for charge transport. In addition, the nanofibers possess a higher specific surface area than conventional micron-sized powders. As a result, the nanofiber electrode exhibits a higher electromotive force and better electro-catalytic activity toward CO oxidation. Therefore, the sensor with the nanofiber electrode shows a higher sensitivity, lower limit of detection and faster response to CO than a sensor with a powder electrode. PMID:22751138

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

    Science.gov (United States)

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

    2012-08-01

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

  19. Characterization of poly(methyl methacrylate) and thermoplastic polyurethane-carbon nanofiber composites produced by chaotic mixing

    Science.gov (United States)

    Jiminez, Guillermo A.

    Chaotic mixing is a novel mixing technique offering high mixing efficiency even under mild shearing conditions. In this work, chaotic mixing was used to prepare composites of carbon nanofibers and two thermoplastic polymers---poly (methyl methacrylate) (PMMA) and thermoplastic polyurethanes (TPU)---and their electrical, mechanical, and thermal properties were evaluated. The TPU systems were based on the reaction products of 4,4'-diphenylmethane diisocyanate, (MDI), soft segment polyol, and 1,4-butanediol as chain extender. Soft segment polyols in the form of poly(propylene glycol) (PPG), and poly(epsilon-caprolactone)diol (PCL) were used to obtain respectively amorphous and crystalline soft segments. Of these, the TPU system based on crystalline soft segment exhibited shape memory effects. Both, as-received untreated carbon nanofibers (CNF) with a very low amount of atomic oxygen on the surface, and oxidized carbon nanofibers (CNFOX) were used. CNFOX was also modified by esterifying with PPG to produce a third type of carbon nanofiber named CNFOL. These carbon nanofibers were examined by X-ray photoelectron spectroscopy to determine the elemental composition of the surface, and by scanning electron microscopy and transmission electron microscopy to determine the surface morphology.

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

    International Nuclear Information System (INIS)

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

  1. Controlling SEI formation on SnSb-porous carbon nanofibers for improved Na ion storage.

    Science.gov (United States)

    Ji, Liwen; Gu, Meng; Shao, Yuyan; Li, Xiaolin; Engelhard, Mark H; Arey, Bruce W; Wang, Wei; Nie, Zimin; Xiao, Jie; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun

    2014-05-01

    Porous carbon nanofiber (CNF)-supported tin-antimony (SnSb) alloys are synthesized and applied as a sodium-ion battery anode. The chemistry and morphology of the solid electrolyte interphase (SEI) film and its correlation with the electrode performance are studied. The addition of fluoroethylene carbonate (FEC) in the electrolyte significantly reduces electrolyte decomposition and creates a very thin and uniform SEI layer on the cycled electrode surface, which an promote the kinetics of Na-ion migration/transportation, leading to excellent electrochemical performance. PMID:24677091

  2. Controlling SEI Formation on SnSb-Porous Carbon Nanofibers for Improved Na Ion Storage

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Liwen; Gu, Meng; Shao, Yuyan; Li, Xiaolin; Engelhard, Mark H.; Arey, Bruce W.; Wang, Wei; Nie, Zimin; Xiao, Jie; Wang, Chong M.; Zhang, Jiguang; Liu, Jun

    2014-05-14

    Porous carbon nanofiber (CNF)-supported tin-antimony (SnSb) alloys is synthesized and applied as sodium ion battery anode. The chemistry and morphology of the solid electrolyte interphase (SEI) film and its correlation with the electrode performance are studied. The addition of fluoroethylene carbonate (FEC) in electrolyte significantly reduces electrolyte decomposition and creates a very thin and uniform SEI layer on the cycled electrode surface which could promote the kinetics of Na-ion migration/transportation, leading to excellent electrochemical performance.

  3. Aerosynthesis: Growths of Vertically Aligned Carbon Nanofibers with Air DC Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kodumagulla, A [North Carolina State University; Varanasi, V [North Carolina State University; Pearce, Ryan [North Carolina State University; Wu, W-C [North Carolina State University; Hensley, Dale K [ORNL; Tracy, Joseph B [North Carolina State University; McKnight, Timothy E [ORNL; Melechko, Anatoli [North Carolina State University

    2014-01-01

    Vertically aligned carbon nanofibers (VACNF) have been synthesized in a mixture of acetone and air using catalytic DC plasma enhanced chemical vapor deposition. Typically, ammonia or hydrogen is used as etchant gas in the mixture to remove carbon that otherwise passivates the catalyst surface and impedes growth. Our demonstration of using air as the etchant gas opens up a possibility that ion etching could be sufficient to maintain the catalytic activity state during synthesis. It also demonstrates the path toward growing VACNFs in open atmosphere.

  4. Preparation and electrochemical performance of heteroatom-enriched electrospun carbon nanofibers from melamine formaldehyde resin.

    Science.gov (United States)

    Ma, Chang; Song, Yan; Shi, Jingli; Zhang, Dongqing; Guo, Quangui; Liu, Lang

    2013-04-01

    Melamine formaldehyde resin was used to prepare heteroatom-enriched carbon nanofibers by electrospinning for the first time. The melamine formaldehyde resin-based carbon fibers without any activation treatment showed a moderate specific surface area ranging from 130 to 479 m2/g and rich surface functionalities (2.56-5.34 wt.% nitrogen and 10.39-11.2 9 wt.% oxygen). Both the specific surface area and surface functionality greatly depended on the carbonization temperature. The capacitive performance was evaluated in 6M KOH aqueous solution. The electrochemically active surface functionalities played an important role in improving the surface capacitance of the electrodes. The sample carbonized at 600°C showed the highest specific surface capacitance of 1.4 F/m2, which was attributed to the most active functionalities (10.69 wt.% of N and O). In addition, the sample carbonized at 750°C exhibited the highest specific capacitance of 206 F/g. PMID:23375805

  5. Preparation of asymmetrically distributed bimetal ceria (CeO?) and copper (Cu) nanoparticles in nitrogen-doped activated carbon micro/nanofibers for the removal of nitric oxide (NO) by reduction.

    Science.gov (United States)

    Bhaduri, Bhaskar; Verma, Nishith

    2014-12-15

    A novel multi-scale web of carbon micro/nanofibers (ACF/CNF) was prepared by the catalytic chemical vapor deposition (CCVD), in which CeO2 and Cu nanoparticles (NPs) were in-situ incorporated during a synthesis step. The CVD temperature was adjusted such that the prepared material had asymmetric distribution of the bimetals, with the Cu NPs located at the tips of the CNFs and the CeO2 particles adhered to the surface of the ACF substrate. The prepared bimetals-dispersed web of ACF/CNF was treated with pyridine and the surface functionalized material was applied for the removal of NO by reduction. The complete reduction of NO was achieved at 500°C and for 400ppm NO concentration. Whereas the Cu NPs acted as the catalyst for the reduction, CeO2 facilitated the incorporation of nitrogen from the pyridine source into the ACF/CNF surface. The produced nitrogen containing surface functional groups enhanced the reactivity of the material toward the NO. The bimetals CeO2 and Cu nanoparticles (NPs)-dispersed ACF/CNF produced in this study is a potential candidate for effectively removing NO by reduction, without requiring urea or ammonia used in conventional abatement methods. PMID:25278359

  6. Transport properties of spiral carbon nanofiber mats containing Pd metal clusters using Pd2(dba)3 as catalyst

    CERN Document Server

    Liu, C J; Hsu, L S; Su, C J; Wang, C C; Shieu, F S

    2004-01-01

    We have grown spiral carbon nanofibers containing Pd metal clusters using the Pd2(dba)3 catalyzed decomposition of gaseous acetylene on molecular sieves (AlPO4-5) support. The microstructure and composition of the spiral carbon nanofibers were examined by the powder x-ray diffractometer and transmission electron microscope. The conductivity of the mat in the temperature range from 14 to 250 K could be described by the form of exp[-(T-1/4)]. The thermopower shows a remarkably linear behavior down to 40 K, reminiscent of some conducting polymers. The sign change of the thermopower suggests there exists more than one type of charge carrier, which could be ascribed to the different types of nanotube with various sizes of radius. The transport behavior of spiral carbon nanofibers containing Pd metal clusters will be discussed in the framework of the heterogeneous model.

  7. Destructive adsorption of Diazinon pesticide by activated carbon nanofibers containing Al2O3 and MgO nanoparticles.

    Science.gov (United States)

    Behnam, Roghaye; Morshed, Mohammad; Tavanai, Hossein; Ghiaci, Mehran

    2013-10-01

    We report the destructive adsorption of Diazinon pesticide by porous webs of activated carbon nanofibers containing Al2O3 and MgO nanoparticles. The results show that, the presence of Al2O3 and MgO nanoparticles in the activated carbon nanofibers increases the amount of destructively adsorbed Diazinon pesticide by activated carbon nanofibers. Moreover, type, amount, and specific surface area of metal oxide nanoparticles affect the adsorption rate as well as the total destructively adsorbed Diazinon. Liquid chromatography proved the degradation of Diazinon by chemical reaction with Al2O3 and MgO nanoparticles. Liquid chromatography-mass spectrometry showed that the main product of reaction between Diazinon and the metal oxides is 2-isopropyl-6-methyl-4-pyrimidinol with less toxicity than Diazinon. PMID:23912227

  8. Fabrication of Homogeneous Multi-walled Carbon Nanotube/ Poly (vinyl alcohol Composite Nanofibers for Microwave Absorption Application

    Directory of Open Access Journals (Sweden)

    Shoushtari A.M.

    2013-09-01

    Full Text Available Poly (vinyl alcohol (PVA / sodium dodecyl sulfate (SDS / multi walled carbon nanotubes (MWCNT camposite nanofibers with various MWCNT contents (up to 10 wt% were fabricated by electrospinning process and their microwave absorption properties were evaluated by a vector network analyzer in the frequency range of 8-12 GHz (X-band at room temperature. The uniform, stable dispersion and well oriented MWCNT within the PVA matrix were achieved through using SDS as dispersing agent. The SEM analysis of the nanofibers samples revealed that the deformation of the nanofibers increases with increasing MWCNT concentration. Very smooth surface of the composite electrospun nanofibers even for the nanofibers with concentration of 10 wt% MWCNT have been successfully prepared because of the high stability dispersion of MWCNT. It was observed that absorption microwave properties improved with increasing in the loading levels of MWCNT. Finally, the PVA/SDS/MWCNT composite nanofibers sample with the 10 wt% content of MWCNT has shown the reflection loss of 15 dB at the frequency of 8 GHz.

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

    Science.gov (United States)

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

    2014-02-01

    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 suitable for oil cleanup under harsh conditions. The outstanding sorption performance of CNF aerogels is associated with their unique physical properties, such as low density, high porosity, excellent mechanical stability, high hydrophobicity and superoleophilicity.

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

    Science.gov (United States)

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

    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 suitable for oil cleanup under harsh conditions. The outstanding sorption performance of CNF aerogels is associated with their unique physical properties, such as low density, high porosity, excellent mechanical stability, high hydrophobicity and superoleophilicity. PMID:24518262

  11. Residual gas analysis of a dc plasma for carbon nanofiber growth

    International Nuclear Information System (INIS)

    We report the analysis of a plasma enhanced chemical vapor deposition process for carbon nanofiber growth. A direct current (dc) plasma is employed with a mixture of acetylene and ammonia. Residual gas analysis is performed on the downstream plasma effluent to determine degrees of precursor dissociation and high molecular weight species formation. Results are correlated to growth quality obtained in the plasma as a function of dc voltage/power, gas mixture, and pressure. Behaviors in plasma chemistry are understood through application of a zero-dimensional model

  12. Electrospun carbon-cobalt composite nanofiber as an anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Carbon-cobalt (C/Co) composite nanofibers with diameters from 100 to 300 nm were prepared by electrospinning and subsequent heat treatment. They were characterized by X-ray diffraction, scanning electron microscopy, galvanostatic cell cycling and impedance spectroscopy. As a lithium storage material, these fibers exhibit excellent electrochemical properties with high reversible capacity (>750 mA h g-1) and good rate capability (578 mA h g-1 at 1 C rate). These composite fibers are a promising anode material for high-power Li-ion batteries

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

    Energy Technology Data Exchange (ETDEWEB)

    Gayen, R.N. [Department of Instrumentation Science, USIC Building, Jadavpur University, Calcutta 700 032 (India); Pal, A.K., E-mail: msakp2002@yahoo.co.in [Department of Instrumentation Science, USIC Building, Jadavpur University, Calcutta 700 032 (India)

    2010-08-15

    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{sup -1} corresponding to the E{sub 2g} tangential stretching mode of an ordered graphitic structure with sp{sup 2} hybridization and a D band at about 1350 cm{sup -1} originating from disordered carbon. Fourier transformed infrared studies indicated the presence of a distinct characteristic absorption peak at {approx}511 cm{sup -1} for Zn-O stretching mode. Photoluminescence spectra indicated band edge luminescence of ZnO at {approx}3.146 eV along with a low intensity peak at {approx}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 10{sup 3} and 3 x 10{sup 3}. Both the values of turn-on field and threshold field for CNF/ZnO were lower than pure ZnO nanorods.

  14. Nonenzymatic glucose sensor based on renewable electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode.

    Science.gov (United States)

    Liu, Yang; Teng, Hong; Hou, Haoqing; You, Tianyan

    2009-07-15

    A novel nonenzymatic glucose sensor was developed based on the renewable Ni nanoparticle-loaded carbon nanofiber paste (NiCFP) electrode. The NiCF nanocomposite was prepared by combination of electrospinning technique with thermal treatment method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that large amounts of spherical nanoparticles were well dispersed on the surface or embedded in the carbon nanofibers. And the nanoparticles were composed of Ni and NiO, as revealed by energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). In application to nonenzymatic glucose determination, the renewable NiCFP electrodes, which were constructed by simply mixing the electrospun nanocomposite with mineral oil, exhibited strong and fast amperometric response without being poisoned by chloride ions. Low detection limit of 1 microM with wide linear range from 2 microM to 2.5 mM (R=0.9997) could be obtained. The current response of the proposed glucose sensor was highly sensitive and stable, attributing to the electrocatalytic performance of the firmly embedded Ni nanoparticles as well as the chemical inertness of the carbon-based electrode. The good analytical performance, low cost and straightforward preparation method made this novel electrode material promising for the development of effective glucose sensor. PMID:19450966

  15. Hard carbon originated from polyvinyl chloride nanofibers as high-performance anode material for na-ion battery.

    Science.gov (United States)

    Bai, Ying; Wang, Zhen; Wu, Chuan; Xu, Rui; Wu, Feng; Liu, Yuanchang; Li, Hui; Li, Yu; Lu, Jun; Amine, Khalil

    2015-03-11

    Two types of hard carbon materials were synthesized through direct pyrolysis of commercial polyvinyl chloride (PVC) particles and pyrolysis of PVC nanofibers at 600-800 °C, respectively, where the nanofibers were prepared by an electrospinning PVC precursors method. These as-prepared hard carbon samples were used as anode materials for Na-ion batteries. The hard carbon obtained from PVC nanofibers achieved a high reversible capacity of 271 mAh/g and an initial Coulombic efficiency of 69.9%, which were much superior to the one from commercial PVC, namely, a reversible capacity of 206 mAh/g and an initial Coulombic efficiency of 60.9%. In addition, the hard carbon originated from the PVC nanofibers exhibited good cycling stability and rate performance: the initial discharge capacities were 389, 228, 194, 178, 147 mAh/g at the current density of 12, 24, 60, 120, and 240 mA/g, respectively, retaining 211 mAh/g after 150 cycles. Such excellent cycle performance, high reversible capacity, and good rate capability enabled this hard carbon to be a promising candidate as anode material for Na-ion battery application. PMID:25692826

  16. Hollow activated carbon nanofibers prepared by electrospinning as counter electrodes for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Hollow activated carbon nanofibers (H-ACNF) were prepared by concentric electrospinning of poly(methyl methacrylate) (PMMA) as a pyrolytic core precursor and polyacrylonitrile (PAN) as a carbon shell precursor, followed by stabilization, carbonization, and activation. The H-ACNF with 190 and 270 nm for core and shell diameter showed excellent mesoporous structure, and 1-D conducting pathway in employing as catalysts of counter electrodes (CEs) for dye-sensitized solar cells (DSCs). The mesoporous structure of H-ACNF represented surface area of 1037.5 m2 g?1 with average mesopore diameter of 17.4 nm. The overall conversion efficiency of H-ACNF is comparable to that of Pt CE because its characteristics promotes the electron and ion transfer, decreases the resistance of charge transfer, and increases the contact area between liquid electrolyte and H-ACNF

  17. A nanobursa mesh: a graded electrospun nanofiber mesh with metal nanoparticles on carbon nanotubes

    Science.gov (United States)

    Senturk-Ozer, Semra; Chen, Tao; Degirmenbasi, Nebahat; Gevgilili, Halil; Podkolzin, Simon G.; Kalyon, Dilhan M.

    2014-07-01

    A new type of material, a ``nanobursa'' mesh (from ``bursa'' meaning ``sac or pouch''), is introduced. This material consists of sequential layers of porous polymeric nanofibers encapsulating carbon nanotubes, which are functionalized with different metal nanoparticles in each layer. The nanobursa mesh is fabricated via a novel combination of twin-screw extrusion and electrospinning. Use of this hybrid process at industrially-relevant rates is demonstrated by producing a nanobursa mesh with graded layers of Pd, Co, Ag, and Pt nanoparticles. The potential use of the fabricated nanobursa mesh is illustrated by modeling of catalytic hydrocarbon oxidation.A new type of material, a ``nanobursa'' mesh (from ``bursa'' meaning ``sac or pouch''), is introduced. This material consists of sequential layers of porous polymeric nanofibers encapsulating carbon nanotubes, which are functionalized with different metal nanoparticles in each layer. The nanobursa mesh is fabricated via a novel combination of twin-screw extrusion and electrospinning. Use of this hybrid process at industrially-relevant rates is demonstrated by producing a nanobursa mesh with graded layers of Pd, Co, Ag, and Pt nanoparticles. The potential use of the fabricated nanobursa mesh is illustrated by modeling of catalytic hydrocarbon oxidation. Electronic supplementary information (ESI) available: Experimental methods and computational details. See DOI: 10.1039/c4nr01145g

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

    International Nuclear Information System (INIS)

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

  19. Morphological characterization of carbon-nanofiber-reinforced epoxy nanocomposites using ultra-small angle scattering

    International Nuclear Information System (INIS)

    Studies of the properties of nanocomposites reinforced with vapor-grown carbon nanofibers (VGCFs) can be found throughout the literature. Electrical, mechanical, viscoelastic, and rheological properties are just a few of the characteristics that have been well discussed. Although these properties depend on morphology, morphological characterization is rare. Due to its 2-dimensional nature, microscopy is of limited value when analyzing network morphologies. This work will show how the characterization of the three-dimensional geometry and network formation of VGCFs can be determined using ultra-small angle scattering techniques. Ultra-small angle x-ray and neutron scattering (USAXS and USANS) were used to characterize the morphology of carbon nanofibers suspended in epoxy. Using a simplified tube model, we estimate the dimensions of suspended fibers. The assumption of tubular fibers accounts for the increased surface area observed with USAXS that is not accounted for using a solid rod model. Furthermore, USANS was used to search for a structural signature associated with the electrical percolation threshold. USANS extends to longer dimensional scales than USAXS, which measures a smaller range of momentum transfer. To determine the electrical percolation threshold, AC impedance spectroscopy was employed to verify that an electrically conductive, percolated network forms at VGCNF loadings of 0.8% < CNF wt% < 1.2%. These values correlate with the USANS data, where a morphrrelate with the USANS data, where a morphological transition is seen at ?1.2% loading.

  20. Label-free detection of C-reactive protein using a carbon nanofiber based biosensor.

    Science.gov (United States)

    Gupta, Rakesh K; Periyakaruppan, Adaikkappan; Meyyappan, M; Koehne, Jessica E

    2014-09-15

    We report the sensitive detection of C-reactive protein (CRP), a biomarker for cardiac disease, using a carbon nanofiber based biosensor platform. Vertically aligned carbon nanofibers were grown using plasma enhanced chemical vapor deposition to fabricate nanoelectrode arrays in a 3×3 configuration. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the CRP detection. The CV responses show a 25% reduction in redox current upon the immobilization of anti-CRP on the electrode where as a 30% increase in charge transfer resistance is seen from EIS. Further reduction in redox current and increase in charge transfer resistance result from binding of CRP on anti-CRP immobilized surface, proportional to the concentration of the CRP target. The detection limit of the sensor is found to be ~90 pM or ~11 ng/ml, which is in the clinically relevant range. Control tests using non-specific myoglobin antigen confirmed the specificity of the present approach. PMID:24709327

  1. Improving Microstructure of Silicon/Carbon Nanofiber Composites as A Li Battery Anode

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Jane Y [ORNL; Burton, David J. [Applied Sciences, Inc.; Meyer III, Harry M [ORNL; Nazri, Maryam [Applied Sciences, Inc.; Nazri, G. Abbas [General Motors Corporation-R& D; Palmer, Andrew C. [Applied Sciences, Inc.; Lake, Patrick D. [Applied Sciences, Inc.

    2013-01-01

    We report the interfacial study of a silicon/carbon nanofiber (Si/CNF) nanocomposite material as a potentially high performance anode for rechargeable lithium ion batteries. The carbon nanofiber is hollow, with a graphitic interior and turbostratic exterior. Amorphous silicon layers were uniformly coated via chemical vapor deposition on both the exterior and interior surfaces of the CNF. The resulting Si/CNF composites were tested as anodes for Li ion batteries and exhibited capacities near 800 mAh g{sup -1} for 100 cycles. After cycling, we found that more Si had fallen off from the outer wall than from the inner wall of CNF. Theoretical calculations confirmed that this is due to a higher interfacial strength at the Si/C-edge interface at the inner wall than that of the Si/C-basal interface at the outer wall. Based upon the experimental analysis and theoretical calculation, we have proposed several interfacial engineering approaches to improve the performance of the electrodes by optimizing the microstructure of this nanocomposite.

  2. Improving microstructure of silicon/carbon nanofiber composites as a Li battery anode

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Jane Y [ORNL; Meyer III, Harry M [ORNL; Burton, David J. [Applied Sciences, Inc.; Qi, Dr. Yue [General Motors Corporation; Nazri, Maryam [Applied Sciences, Inc.; Nazri, G. Abbas [General Motors Corporation-R& D; Palmer, Andrew C. [Applied Sciences, Inc.; Lake, Patrick D. [Applied Sciences, Inc.

    2013-01-01

    We report the interfacial study of a silicon/carbon nanofiber (Si/CNF) nanocomposite material as a potentially high performance anode for rechargeable lithium ion batteries. The carbon nanofiber is hollow, with a graphitic interior and turbostratic exterior. Amorphous silicon layers were uniformly coated via chemical vapor deposition on both the exterior and interior surfaces of the CNF. The resulting Si/CNF composites were tested as anodes for Li ion batteries and exhibited capacities near 800 mAh g1 for 100 cycles. After cycling, we found that more Si had fallen off from the outer wall than from the innerwall of CNF. Theoretical calculations confirmed that this is due to a higher interfacial strength at the Si/Cedge interface at the inner wall than that of the Si/C-basal interface at the outer wall. Based upon the experimental analysis and theoretical calculation, we have proposed several interfacial engineering approaches to improve the performance of the electrodes by optimizing the microstructure of this nanocomposite.

  3. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Skowronski, J.M. [Poznan University of Technology, Institute of Chemistry and Technical Electrochemistry, ul. Piotrowo 3, 60-965 Poznan (Poland)]. E-mail: Jan.Skowronski@put.poznan.pl; Czerwinski, A. [Warsaw University, Department of Chemistry, ul. Pasteura 1, 02-093 Warsaw (Poland); Rozmanowski, T. [Poznan University of Technology, Institute of Chemistry and Technical Electrochemistry, ul. Piotrowo 3, 60-965 Poznan (Poland); Rogulski, Z. [Industrial Chemistry Research Institute, ul. Rydygiera 8, 01-793 Warsaw (Poland); Krawczyk, P. [Poznan University of Technology, Institute of Chemistry and Technical Electrochemistry, ul. Piotrowo 3, 60-965 Poznan (Poland)

    2007-05-10

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

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

    International Nuclear Information System (INIS)

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

  6. Investigation of Lithium-Air Battery Discharge Product Formed on Carbon Nanotube and Nanofiber Electrodes

    Science.gov (United States)

    Mitchell, Robert Revell, III

    Carbon nanotubes have been actively investigated for integration in a wide variety of applications since their discovery over 20 years ago. Their myriad desirable material properties including exceptional mechanical strength, high thermal conductivities, large surface-to-volume ratios, and considerable electrical conductivities, which are attributable to a quantum mechanical ability to conduct electrons ballistically, have continued to motivate interest in this material system. While a variety of synthesis techniques exist, carbon nanotubes and nanofibers are most often conveniently synthesized using chemical vapor deposition (CVD), which involves their catalyzed growth from transition metal nanoparticles. Vertically-aligned nanotube and nanofiber carpets produced using CVD have been utilized in a variety of applications including those related to energy storage. Li-air (Li-O2) batteries have received much interest recently because of their very high theoretical energy densities (3200 Wh/kgLi2O2 ). which make them ideal candidates for energy storage devices for future fully-electric vehicles. During operation of a Li-air battery O2 is reduced on the surface a porous air cathode, reacting with Li-ions to form lithium peroxide (Li-O2). Unlike the intercalation reactions of Li-ion batteries, discharge in a Li-air cell is analogous to an electrodeposition process involving the nucleation and growth of the depositing species on a foreign substrate. Carbon nanofiber electrodes were synthesized on porous substrates using a chemical vapor deposition process and then assembled into Li-O2 cells. The large surface to volume ratio and low density of carbon nanofiber electrodes were found to yield a very high gravimetric energy density in Li-O 2 cells, approaching 75% of the theoretical energy density for Li 2O2. Further, the carbon nanofiber electrodes were found to be excellent platforms for conducting ex situ electron microscopy investigations of the deposition Li2O2 phase, which was found to have unique disc and toroid morphologies. Subsequent studies were conducted using freestanding carpets of multi-walled CNT arrays, which were synthesized using a modified CVD process. The freestanding CNT arrays were used as a platform for studying the morphological evolution of Li2O2 discharge product as a function of rate and electrode capacity. SEM imaging investigations found that the Li2O 2 particles underwent a shape evolution from discs to toroids as their size increased. TEM imaging and diffraction studies showed that the microscale Li2O2 particles are composed of stacks of thin Li 2O2 crystallites and that splaying of the stacked crystallite array drives the observed disc to toroid transition. Modeling was performed to gain insights into the nucleation and growth processes involved during discharge in Li-O2 cells. The modeling study suggests that poor electronic conductivity of the depositing phase limits the rate capability obtainable in Li-O2 cells. Modeling can provide substantial insights into paths toward electrode optimization. Understanding the size and shape evolution of Li2O2 particles and engineering improved electrode architectures is critical to efficiently filling the electrode void volume during discharge thereby improving the volumetric energy density of Li-O2 batteries. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  7. Radiation grafting of methacrylate onto carbon nanofiber surface

    International Nuclear Information System (INIS)

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

  8. 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 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. Electronic supplementary information (ESI) available: Characteristic chemical shifts/transmittances of ATR/FT-IR spectral bands for SWCNT-PANi EB composite membranes under different numbers of flash welds at full power can be seen in Table S1. See DOI: 10.1039/c3nr00441d

  9. Grafting of vapor-grown carbon nanofibers (VGCNF) with a hyperbranched poly(ether-ketone)

    International Nuclear Information System (INIS)

    An in-situ polymerization of an A2B monomer, 5-phenoxyisophthalic acid, in the presence of various amounts (5, 10 and 20 wt%) of vapor-grown carbon nanofibers (VGCNF) was carried out in poly(phosphoric acid)/phosphorus pentoxide (PPA/P2O5; 1:4, w/w) medium. 5-Phenoxyisophthalic acid polymerizes via Friedel-Crafts acylation in PPA to form a CO2H-terminated hyperbranched poly(ether-ketone) or HPB-PEK. The resulting (HPB-PEK)-g-VGCNF composites were not soluble in dichlorobenzene or toluene, but also showed significant solubility in polar solvents such as NMP, DMF, DMAC, ethanol, and significantly higher solubility in ethanol/triethylamine mixture or in aqueous ammonia solution, apparently stemming from the ionization of the numerous surface CO2H groups. This is in contrast to the nanocomposites derived from VGCNF grafted with a linear meta-poly(ether-ketone), mPEK, with 1-10 wt% VGCNF content that have much lower solubility in these polar solvents but are more soluble in methanesulfonic acid [J.-B. Baek, C.B. Lyons, L.-S. Tan, Macromolecules 37 (2004) 8278]. The overall evidence based on the data from elemental analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR) as well as scanning electron microscopy of the resulting materials implicates that under our reaction conditions, HPB-PEK was grafted to the surfaces of VGCNF resulting in the formation of highly coated nanofibers. TGAformation of highly coated nanofibers. TGA data also support that VGCNF has remained more or less structurally intact under the mildly acidic, relatively high-shearing and hot polymerization conditions

  10. Nanographene derived from carbon nanofiber and its application to electric double-layer capacitors

    International Nuclear Information System (INIS)

    The fascinating properties of graphene are attracting considerable attention in engineering fields such as electronics, optics, and energy engineering. These properties can be controlled by controlling graphene's structure, e.g., the number of layers and the sheet size. In this study, we synthesized nanosized graphene from a platelet-type carbon nanofiber. The thickness and size of nanographene oxide are around 1 nm and 60 nm and we obtained nanographene by hydrazine reduction of nanographene oxide. We applied the nanographene to an ionic-liquid electric double-layer capacitor (EDLC), which exhibited a much larger capacitance per specific surface area than an EDLC using conventional activated carbon. Furthermore, the capacitance increased significantly with increasing cycle time. After 30th cycle, the capacitance was achieved 130 F g?1, though the surface area was only 240 m2 g?1. These results suggest that nanographene structure induce the capacitance enhancement.

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

    Directory of Open Access Journals (Sweden)

    Dong Liu

    2010-01-01

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

  12. 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

  13. 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.

  14. 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 ?-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 ?-phase, indicating that the shear force during electrospinning might favor the ?-phase, similarly to the conventional fiber spinning.

  15. EFFECT OF CELLULOSE NANOFIBERS ISOLATED FROM BAMBOO PULP RESIDUE ON VULCANIZED NATURAL RUBBER

    Directory of Open Access Journals (Sweden)

    P. M. Visakh,

    2012-02-01

    Full Text Available Nanocomposites were prepared using two bioresources, viz., cellulose nanofibers (CNFs extracted from bamboo paper-pulp waste as the reinforcing phase and natural rubber (NR as the matrix phase. CNFs with diameters up to 50 nm were isolated from bamboo pulp waste, and nanocomposites with 5 and 10% CNFs were obtained via two-roll mill mixing of solid natural rubber with a master batch containing 20 wt% CNFs. The NR phase was cross-linked using sulphur vulcanization. The morphology studies showed that the dispersion of CNF in NR matrix was not optimal, and some aggregates were visible on the fracture surface. The tensile strength and modulus at 50% elongation increased for the nanocomposites with the addition of CNFs, accompanied by a moderate decrease in elongation at break. The storage modulus of the natural rubber significantly increased above its glass-rubber transition temperature upon nanofiber addition. The addition of CNFs also had a synergistic impact on the thermal stability of natural rubber. The susceptibility to organic solvents decreased significantly for the nanocomposites compared to crosslinked NR, which indicated restriction of polymer chain mobility in the vicinity of the nanosized CNFs in the NR matrix.

  16. Effects of spatial separation on the growth of vertically aligned carbon nanofibers produced by plasma-enhanced chemical vapor deposition

    Science.gov (United States)

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

    2002-01-01

    Vertically aligned carbon nanofibers (VACNFs) with vastly different spacing were grown by catalytically controlled dc glow discharge chemical vapor deposition. Both densely packed VACNFs and essentially isolated VACNFs were studied using scanning electron microscopy and x-ray energy dispersive spectroscopy. The morphology and chemical composition of isolated VACNFs were found to have a strong dependence upon the growth conditions, in particular on the C2H2/NH3 gas mixture used. This is attributed to the sidewalls of isolated VACNFs being exposed to reactive species during growth. In contrast, the sidewalls of densely packed VACNFs were shielded by the neighboring VACNFs, so that their growth occurred mainly in the vertical direction, by diffusion of carbon through the catalyst nanoparticle and subsequent precipitation at the nanofiber/nanoparticle interface. These striking differences in the growth process result in the formation of flattened carbon nanostructures (carbon nanotriangles) and also are quite important for the realization of VACNF-based devices.

  17. Effects of spatial separation on the growth of vertically aligned carbon nanofibers produced by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Vertically aligned carbon nanofibers (VACNFs) with vastly different spacing were grown by catalytically controlled dc glow discharge chemical vapor deposition. Both densely packed VACNFs and essentially isolated VACNFs were studied using scanning electron microscopy and x-ray energy dispersive spectroscopy. The morphology and chemical composition of isolated VACNFs were found to have a strong dependence upon the growth conditions, in particular on the C2H2/NH3 gas mixture used. This is attributed to the sidewalls of isolated VACNFs being exposed to reactive species during growth. In contrast, the sidewalls of densely packed VACNFs were shielded by the neighboring VACNFs, so that their growth occurred mainly in the vertical direction, by diffusion of carbon through the catalyst nanoparticle and subsequent precipitation at the nanofiber/nanoparticle interface. These striking differences in the growth process result in the formation of flattened carbon nanostructures (carbon nanotriangles) and also are quite important for the realization of VACNF-based devices

  18. 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.

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

    International Nuclear Information System (INIS)

    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?3. The DSF of the CNF ranged from 1.8 to 2.3, indicating highly non-spherical particle morphologies.

  20. Oriented carbon nanostructures grown by hot-filament plasma-enhanced CVD from self-assembled Co-based catalyst on Si substrates

    Science.gov (United States)

    Fleaca, Claudiu Teodor; Morjan, Ion; Rodica, Alexandrescu; Dumitrache, Florian; Soare, Iuliana; Gavrila-Florescu, Lavinia; Sandu, Ion; Dutu, Elena; Le Normand, François; Faerber, Jacques

    2012-03-01

    We report the synthesis of coral- and caterpillar-like carbon nanostructures assemblies starting from cobalt nitrate ethanol solutions deposited by drop-casting onto blank or carbon nanoparticles film covered Si(1 0 0) substrates. The seeded films were pre-treated with glow discharge hydrogen plasma aided by hot-filaments at 550 °C followed by introduction of acetylene at 700 °C. The resultant carbon nanostructure assemblies contain a high density of aligned carbon nanotubes/nanofibers (CNTs/CNFs). The influence of the forces that act during liquid-mediated self-assembly of Co catalyst precursor is discussed.

  1. Functional properties of electrospun NiO/RuO2 composite carbon nanofibers

    International Nuclear Information System (INIS)

    Highlights: ? Fabrication of carbon nanofibers with nickel–ruthenium composites by electrospinning. ? An interesting observation of increase in capacitance with increase in the number of cycles for supercapacitor applications. ? Li ion battery testing showed a stable capacity ranging from 350 mAh g?1 to 400 mAh g?1. ? Lower impedance with the incorporation of 15 wt% Ru precursor than those without Ru. - Abstract: One-dimensional (1D) nickel oxide/ruthenium oxide (NiO/RuO2)–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 LiPF6 (EC;DMC) electrolyte. NiRu–C–NFs fabricated from 5 wt% nickel (II) and 15 wt% ruthenium (III) precursors showed a capacitance up to ?60 F g?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?1 at current rate of 72 mA g?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.

  2. Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

    Science.gov (United States)

    Tan, Seng; Zhou, Jian-guo

    2013-01-01

    Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

  3. High power direct methanol fuel cell with a porous carbon nanofiber anode layer

    International Nuclear Information System (INIS)

    Highlights: • This study demonstrates a novel porous carbon nanofiber anode (PNCF) layer. • PNFC anode layer DMFC presents power density of 23.0 mW cm?2. • This unit operates at room temperature and consumes low concentration of methanol. - Abstract: Three anode electrodes containing Pt–Ru Black as a catalyst were fabricated with a porous layer made with different carbon materials: carbon black (CB), carbon nanofiber (CNF) and a combination of both carbon materials (CB + CNF). The carbon-based porous layer was coated onto a carbon cloth with PTFE pre-treatment for delivering hydrophobic properties and applied in direct methanol fuel cells (DMFCs). Characterisation of electrochemical properties for three different anode electrodes was performed with cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature in a half-cell configuration. The evolution of the surface morphology of diffusion layer and electrodes was characterised by using variable-pressure scanning electron microscopy (VP-SEM). The electrochemical results indicate that electrode with CNF layer showed the highest current densities compared to CB and CB + CNF with the same catalyst loading. VP-SEM measurements show the network formation within the structure, which could facilitate the methanol mass transfer and improve the catalyst efficiency. The electrodes were applied to a single-cell DMFC, and the cell performance was experimentally investigated under passive operating mode and room temperature. A maximum power density of 23.0 mW cm?2 at a current density of 88.0 mA cm?2 with a 3 M dilute methanol solution was achieved. The results show that the electrodes with a CNF layer could improve the performance of DMFC as compared with commercially used CB and prove it’s potentially application in DMFC technology especially for portable power source applications due to several advantages as followings: operating at low concentration of methanol, operating at room temperature, low catalyst loading in anode and cathode, cheaper, less hazardous and no parasitic load

  4. Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation

    Science.gov (United States)

    Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2012-10-01

    Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

  5. Carbon Nanofiber Reinforced and PU-toughened POM Ternary Composites: Friction, Wear and Creep Properties

    Directory of Open Access Journals (Sweden)

    Suchart Siengchin

    2011-12-01

    Full Text Available Composites composed of polyoxymethylene (POM, polyurethane (PU and carbon nanofiber (CNF were produced by water-mediated melt compounding. PU latex and/or aqueous CNF dispersion were introduced into the molten POM in laboratory kneader to prepare toughened and/or nanoreinforced POM composites. The dispersion of the CNF was inspected using scanning electron microscopy (SEM. The mechanical properties (friction, wear and creep strain of the composites were determined by roller (steel-on-plate (ROP and creep tensile tests. It was found that CNF worked as a reinforcement and improved the coefficient of friction (COF and wear. It was also found that, the creep resistance decreases with increasing time, temperature and addition of CNF.

  6. Damage detection and conductivity evolution in carbon nanofiber epoxy via electrical impedance tomography

    Science.gov (United States)

    Tallman, T. N.; Gungor, S.; Wang, K. W.; Bakis, C. E.

    2014-04-01

    Utilizing electrically conductive nanocomposites for integrated self-sensing and health monitoring is a promising area of structural health monitoring (SHM) research wherein local changes in conductivity coincide with damage. In this research we conduct proof of concept investigations using electrical impedance tomography (EIT) for damage detection by identifying conductivity changes and by imaging conductivity evolution in a carbon nanofiber (CNF) filled epoxy composite. CNF/epoxy is examined because fibrous composites can be manufactured with a CNF/epoxy matrix thereby enabling the entire matrix to become self-sensing. We also study the mechanisms of conductivity evolution in CNF/epoxy through electrical impedance spectroscopy (EIS) testing. The results of these tests indicate that thermal expansion is responsible for conductivity evolution in a CNF/epoxy composite.

  7. Electrochemical behavior of activated carbon nanofiber-vanadium pentoxide composites for double-layer capacitors

    International Nuclear Information System (INIS)

    Mesopore-enriched activated carbon nanofiber (ACNF) mats are produced by incorporating vanadium(V) oxide (V2O5) into polyacrylonitrile (PAN) via electrospinning, and their electrochemical properties are investigated as an electrode in supercapacitors. The microstructures of the ACNFs (e.g., nanometer-size diameter, high specific surface area, narrow pore size distribution, and tunable porosity) are changed, and the textural parameters are found to affect the electrochemical properties significantly through the different V2O5 loadings and activation process. The V2O5/PAN-based ACNF electrodes with well-balanced micro/mesoporosity having an optimal pore range for effective double layer formation in an organic medium are expected to be useful electrode materials for supercapacitor applications

  8. Zinc oxide/activated carbon nanofiber composites for high-performance supercapacitor electrodes

    Science.gov (United States)

    Kim, Chang Hyo; Kim, Bo-Hye

    2015-01-01

    ZnO-containing porous activated carbon nanofibers (ZnO/ACNFs) are prepared through one-step electrospinning using zinc acetate and polyacrylonitrile (PAN), followed by thermal treatment. The electrochemical performance of the ZnO/ACNF composite electrodes is compared to that of pure ACNF electrodes in aqueous KOH as the electrolyte. Electrochemical measurements of ZnO/ACNFs reveal a maximum specific capacitance of 178.2 Fg-1, and high energy densities of 22.71-17.77 Whkg-1 in the power density range of 400 to 4000 W kg-1. Furthermore, this supercapacitor electrode exhibits excellent cycle life with a specific capacitance ?75% of the initial value after 1000 cycles. The combination of ACNF's high surface area with ZnO's large specific capacity facilitates a synergistic effect between ZnO's faradaic capacitance and ACNF's double layer capacitance, which afforded good capacitive behavior.

  9. Supercapacitors based on 3D network of activated carbon nanowhiskers wrapped-on graphitized electrospun nanofibers

    Science.gov (United States)

    He, Shuijian; Chen, Linlin; Xie, Chencheng; Hu, Huan; Chen, Shuiliang; Hanif, Muddasir; Hou, Haoqing

    2013-12-01

    Due to their cycling stability and high power density, the supercapacitors bridge the power/energy gap between traditional dielectric capacitors and batteries/fuel cells. Electrode materials are key components for making high performance supercapacitors. An activated carbon nanowhiskers (ACNWs) wrapped-on graphitized electrospun nanofiber (GENF) network (ACNWs/GENFN) with 3D porous structure is prepared as a new type of binder-free electrode material for supercapacitors. The supercapacitor based on the ACNWs/GENFN composite material displays an excellent performance with a specific capacitance of 176.5 F g-1 at current density of 0.5 A g-1, an ultrahigh power density of 252.8 kW kg-1 at current density of 800 A g-1 and an outstanding cycling stability of no capacitance loss after 10,000 charge/discharge cycles.

  10. Electrochemical properties of carbon nanofiber web as an electrode for supercapacitor prepared by electrospinning

    Science.gov (United States)

    Kim, C.; Yang, K. S.

    2003-08-01

    Poly(acrylonitrile) solutions in dimethylformamide were electrospun to be webs consisting of 300 nm ultrafine fibers. The webs were oxidatively stabilized and activated by steam resulting in activated carbon nanofibers (ACNFs). The specific surface area of the ACNF activated at 700 °C was the highest but mesopore volume fraction of that was lowest. On the other hand, the ACNFs activated at 800 °C showed opposite trends to those activated at 700 °C. The high specific surface area, mainly due to the micropores, introduced maximum specific capacitance at low current density (173 F/g at 10 mA/g). The elevated volume fraction of mesopores gave maximum specific capacitance at high current density (120 F/g at 1000 mA/g). The behavior is explained on the basis of ion mobility in the pores.

  11. Mechanisms for catalytic carbon nanofiber growth studied by ab initio density functional theory calculations

    DEFF Research Database (Denmark)

    Abild-Pedersen, Frank; NØrskov, Jens Kehlet

    2006-01-01

    Mechanisms and energetics of graphene growth catalyzed by nickel nanoclusters were studied using ab initio density functional theory calculations. It is demonstrated that nickel step-edge sites act as the preferential growth centers for graphene layers on the nickel surface. Carbon is transported from the deposition site at the free nickel surface to the perimeter of the growing graphene layer via surface or subsurface diffusion. Three different processes are identified to govern the growth of graphene layers, depending on the termination of the graphene perimeter at the nickel surface, and it is argued how these processes may lead to different nanofiber structures. The proposed growth model is found to be in good agreement with previous findings.

  12. 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)

  13. A feasibility study of self-heating concrete utilizing carbon nanofiber heating elements

    International Nuclear Information System (INIS)

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

  14. Development of methods of growing carbon nanofibers on silica glass fiber supports

    Energy Technology Data Exchange (ETDEWEB)

    Ismagilov, Zinfer R.; Shikina, Nadezhda V.; Kruchinin, Vladimir N.; Rudina, Nina A.; Ushakov, Vladimir A.; Vasenin, Nikolai T. [Boreskov Institute of Catalysis, Novosibirsk 630090 (Russian Federation); Veringa, Hubert J. [Energy research Centre of the Netherlands ECN, P.O. Box 1, 1755 ZG Petten (Netherlands)

    2005-05-15

    Samples of carbon nanofibers (CNF) with different carbon contents (6.5-55wt.%) are prepared by decomposition of CH{sub 4} on Ni catalysts supported on silica glass fibers (SGF). The incipient wetness impregnation of support, introduction of the active component into alumina washcoat and ion-exchange methods were used to prepare Ni catalysts on SGF. On the optimal catalyst prepared on washcoated SGF, carbon forms as CNF of diameter 20-50nm, and the carbon capacity is rather high-55g{sub C}/g{sub Ni}. Diameter of the CNF corresponds to the size of catalyst particles of Ni metal, which have the cuboctahedral form typical for the formation of CNF with conical embedding of graphite layers with respect to the filament axis. The SGF with supported CNF is a mesoporous material with polydisperse pore distribution similar by structural and textural parameters to the granulated bulk CNF obtained in methane decomposition over high-loaded nickel-alumina catalysts. The XRD, ESR and DTA methods were used for phase and structural analysis and demonstrated that CNF has a uniform graphite-like structure and does not include the amorphous phase.

  15. 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

    2013-01-01

    Durability issues have recently been given much attention in Proton Exchange Membrane Fuel Cell (PEMFC) research. It gives fundamental definition for cell life time, capital cost, system stability and technique reliability. Loss of catalyst surface area due to corrosion of supporting material (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 to different morphology of the nano carbons compared to Vulcan XC 72 the electrode structures may still need optimization to improve overall cell performance.

  16. Reversible Hydrogen Storage in Electrospun Composite Nanofibers

    OpenAIRE

    Haji A.; Nasouri K.; Mousavi Shoushtari A.; Kaflou A.

    2013-01-01

    Composite nanofibers containing single-walled carbon nanotubes (SWNT) were prepared by using elec-trospinning technique and hydrogen adsorption/desorption isotherms were carried out by a Sieverts appa-ratus at room temperature. The SEM analysis of the nanofibers revealed that the deformation of the nano-fiber increases with increasing SWNT concentration. The diameter of neat nanofibers was below 200 nm and had smooth surface. The surface of the composite nanofibers was rough even by adding lo...

  17. Chamber-confined silicon-carbon nanofiber composites for prolonged cycling life of Li-ion batteries

    Science.gov (United States)

    Fu, Kun; Lu, Yao; Dirican, Mahmut; Chen, Chen; Yanilmaz, Meltem; Shi, Quan; Bradford, Philip D.; Zhang, Xiangwu

    2014-06-01

    Silicon is a promising high capacity (4200 mA h g-1) anode material for lithium ion batteries but the significant volume change (over 300%) of silicon during lithiation/delithiation remains a challenge in terms of silicon pulverization and solid-electrolyte-interphase (SEI) accumulation in the silicon composite electrode. To alleviate the volumetric change of silicon, we built a flexible and self-supporting carbon-enhanced carbon nanofiber (CNF) structure with vacant chamber to encapsulate Si nanoparticles (vacant Si@CNF@C). This composite was tested directly without any polymer and current collector. The confined vacant chamber allowed the increasing volume of silicon and SEI accumulates to be well retained for a long cycle life. This chamber-confined silicon-carbon nanofiber composite exhibited an improved performance in terms of good cycling performance (620 mA h g-1), high coulombic efficiency (99%), and good capacity retention (80%) after 200 cycles. This self-supported silicon-carbon nanofiber structure showed high flexibility and good electrochemical performance for the potential as flexible electrode for lithium-ion batteries.

  18. 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)

  19. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO2-coated carbon nanofibers

    International Nuclear Information System (INIS)

    This work reported basically aims at understanding the extent of SiO2-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 SiO2 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. Au Coating of Carbon Nanofiber-Tipped SPM Probes for Immobilization of Thiolated Biomolecules

    International Nuclear Information System (INIS)

    An argon-ion-induced carbon nanofiber (CNF) is expected to be an ideal nanocarbon for developing probes for scanning probe microscopes (SPM) owing to its superior physical properties and structures. To use this pristine CNF as a biofunctionalized SPM probe, its surface needs to be further modified with probing molecules that have specific biochemical affinities toward biological targets. In this study, using a carbon-coated Si wafer as a substitute for a CNF-tipped SPM probe, we investigated ion sputtering for the formation of an Au film on a carbon surface, followed by thermal annealing for making the Au-crystal orientation preferable for the chemisorption of thiolated biomolecules. Finally, we confirmed the biofunctionality of the immobilized thiolated oligonucleotide probe on the annealed Au film in order to hybridize it with the complementary oligonucleotide target. The hybrids were detected by fluorescence emitted from streptavidin-conjugated quantum dots tagged to the biotin molecules. From these results, it was shown that Au coating, thermal annealing, and the subsequent immobilization of thiolated biomolecules can be used for the development of new biofunctional CNF-tipped SPM probes.

  1. Au Coating of Carbon Nanofiber-Tipped SPM Probes for Immobilization of Thiolated Biomolecules

    Science.gov (United States)

    Park, S.; Goto, H.; Saito, T.; Sonoda, T.; Kitazawa, M.; Tanemura, M.

    2013-03-01

    An argon-ion-induced carbon nanofiber (CNF) is expected to be an ideal nanocarbon for developing probes for scanning probe microscopes (SPM) owing to its superior physical properties and structures. To use this pristine CNF as a biofunctionalized SPM probe, its surface needs to be further modified with probing molecules that have specific biochemical affinities toward biological targets. In this study, using a carbon-coated Si wafer as a substitute for a CNF-tipped SPM probe, we investigated ion sputtering for the formation of an Au film on a carbon surface, followed by thermal annealing for making the Au-crystal orientation preferable for the chemisorption of thiolated biomolecules. Finally, we confirmed the biofunctionality of the immobilized thiolated oligonucleotide probe on the annealed Au film in order to hybridize it with the complementary oligonucleotide target. The hybrids were detected by fluorescence emitted from streptavidin-conjugated quantum dots tagged to the biotin molecules. From these results, it was shown that Au coating, thermal annealing, and the subsequent immobilization of thiolated biomolecules can be used for the development of new biofunctional CNF-tipped SPM probes.

  2. 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 155?Acm(-2) for PAN, PAN-AC and PAN-GR, respectively) compared to the graphite electrode (11.5?Acm(-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

  3. Grafting of vapor-grown carbon nanofibers (VGCNF) with a hyperbranched poly(ether-ketone)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, David H. [University of Dayton Research Institute, Dayton, OH 45469-0168 (United States); Baek, Jong-Beom [Department of Industrial Chemistry, Chungbuk National University, Chungbuk 361-763 (Korea, Republic of); Tan, Loon-Seng [Polymer Branch, AFRL/MLBP, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7750 (United States)]. E-mail: loon-seng.tan@wpafb.af.mil

    2006-07-25

    An in-situ polymerization of an A{sub 2}B monomer, 5-phenoxyisophthalic acid, in the presence of various amounts (5, 10 and 20 wt%) of vapor-grown carbon nanofibers (VGCNF) was carried out in poly(phosphoric acid)/phosphorus pentoxide (PPA/P{sub 2}O{sub 5}; 1:4, w/w) medium. 5-Phenoxyisophthalic acid polymerizes via Friedel-Crafts acylation in PPA to form a CO{sub 2}H-terminated hyperbranched poly(ether-ketone) or HPB-PEK. The resulting (HPB-PEK)-g-VGCNF composites were not soluble in dichlorobenzene or toluene, but also showed significant solubility in polar solvents such as NMP, DMF, DMAC, ethanol, and significantly higher solubility in ethanol/triethylamine mixture or in aqueous ammonia solution, apparently stemming from the ionization of the numerous surface CO{sub 2}H groups. This is in contrast to the nanocomposites derived from VGCNF grafted with a linear meta-poly(ether-ketone), mPEK, with 1-10 wt% VGCNF content that have much lower solubility in these polar solvents but are more soluble in methanesulfonic acid [J.-B. Baek, C.B. Lyons, L.-S. Tan, Macromolecules 37 (2004) 8278]. The overall evidence based on the data from elemental analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR) as well as scanning electron microscopy of the resulting materials implicates that under our reaction conditions, HPB-PEK was grafted to the surfaces of VGCNF resulting in the formation of highly coated nanofibers. TGA data also support that VGCNF has remained more or less structurally intact under the mildly acidic, relatively high-shearing and hot polymerization conditions.

  4. Fabrication of Homogeneous Multi-Walled Carbon Nanotube/ Poly (Vinyl Alcohol) Composite Nanofibers for Microwave Absorption Application

    OpenAIRE

    Shoushtari A.M.; Salimbeygi G.; Nasouri K.; Haji A.

    2013-01-01

    Poly (vinyl alcohol) (PVA) / sodium dodecyl sulfate (SDS) / multi walled carbon nanotubes (MWCNT) camposite nanofibers with various MWCNT contents (up to 10 wt%) were fabricated by electrospinning process and their microwave absorption properties were evaluated by a vector network analyzer in the frequency range of 8 – 12 GHz (X-band) at room temperature. The uniform, stable dispersion and well oriented MWCNT within the PVA matrix were achieved through using SDS as dispersing agent. The SEM...

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

    Science.gov (United States)

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

    2011-05-01

    In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry. PMID:21780388

  6. Fabrication, structure, and magnetic properties of electrospun carbon/cobalt ferrite (C/CoFe2O4) composite nanofibers

    Science.gov (United States)

    Nilmoung, S.; Kidkhunthod, P.; Pinitsoontorn, S.; Rujirawat, S.; Yimnirun, R.; Maensiri, S.

    2015-02-01

    This work reports the fabrication and properties of carbon/cobalt ferrite (C/CoFe2O4) composite nanofibers by using electrospinning technique followed by carbonization process under mixed air and argon atmosphere. The as-prepared samples were characterized by means of thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray absorption spectroscopy, and vibrating sample magnetometry. It was found that the structure of CoFe2O4 was cubic spinel with the variation of crystallite size between 22 and 54 nm depending on the magnetic source content. X-ray absorption near-edge spectra at the Fe (7,112 eV) and Co (7,709 eV) absorption K-edge were used to confirm the Fe3+ and Co2+ oxidation states of CoFe2O4 nanoparticles. The X-ray absorption fine structure analysis indicated that CoFe2O4 nanoparticles had a structure analogous to bulk-inverted spinel structure. All composite nanofibers exhibited ferromagnetic behavior related to the distribution of cations over tetrahedral and octahedral sites, whereas diamagnetic behavior was observed in pure carbon nanofibers. The magnetization was clearly enhanced with respect to the increase of magnetic source content, whereas the coercivity and the squareness (M r/M s) were dependent of crystallite size.

  7. Fabrication, structure, and magnetic properties of electrospun carbon/cobalt ferrite (C/CoFe2O4) composite nanofibers

    Science.gov (United States)

    Nilmoung, S.; Kidkhunthod, P.; Pinitsoontorn, S.; Rujirawat, S.; Yimnirun, R.; Maensiri, S.

    2015-04-01

    This work reports the fabrication and properties of carbon/cobalt ferrite (C/CoFe2O4) composite nanofibers by using electrospinning technique followed by carbonization process under mixed air and argon atmosphere. The as-prepared samples were characterized by means of thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray absorption spectroscopy, and vibrating sample magnetometry. It was found that the structure of CoFe2O4 was cubic spinel with the variation of crystallite size between 22 and 54 nm depending on the magnetic source content. X-ray absorption near-edge spectra at the Fe (7,112 eV) and Co (7,709 eV) absorption K-edge were used to confirm the Fe3+ and Co2+ oxidation states of CoFe2O4 nanoparticles. The X-ray absorption fine structure analysis indicated that CoFe2O4 nanoparticles had a structure analogous to bulk-inverted spinel structure. All composite nanofibers exhibited ferromagnetic behavior related to the distribution of cations over tetrahedral and octahedral sites, whereas diamagnetic behavior was observed in pure carbon nanofibers. The magnetization was clearly enhanced with respect to the increase of magnetic source content, whereas the coercivity and the squareness ( M r/ M s) were dependent of crystallite size.

  8. The Optimization of Electrical Conductivity Using Central Composite Design for Polyvinyl Alcohol/Multiwalled Carbon Nanotube-Manganese Dioxide Nanofiber Composites Synthesised by Electrospinning

    OpenAIRE

    Ahmad Zuhairi Abdullah; Sharif Hussein Sharif Zein; Mohd Faiz Muaz Ahmad Zamri; Nor Irwin Basir

    2012-01-01

    This research reports the characterization and statistical analysis of electrical conductivity optimization for polyvinyl alcohol (PVA)/multiwalled carbon nanotube (MWCNT)-manganese dioxide (MnO2) nanofiber composite. The Central Composite Design (CCD), the most common design of Response Surface Methodology (RSM) had been used to optimise the synthesis process of PVA/MWCNT-MnO2 nanofiber composite. The process parameters studied were; applied voltage (16 kV - 30 kV), solution flow rate (3- 5 ...

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

    Science.gov (United States)

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

    2015-01-01

    Summary Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO) is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM) has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT)-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF) as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency. PMID:25671165

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

    Science.gov (United States)

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

    2013-02-28

    We report an electrochemical method for measuring the activity of proteases using nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). The VACNFs of ~150 nm in diameter and 3 to 5 ?m in length were grown on conductive substrates and encapsulated in SiO2 matrix. After polishing and plasma etching, controlled VACNF tips are exposed to form an embedded VACNF NEA. Two types of tetrapeptides specific to cancer-mediated proteases legumain and cathepsin B are covalently attached to the exposed VACNF tip, with a ferrocene (Fc) moiety linked at the distal end. The redox signal of Fc can be measured with AC voltammetry (ACV) at ~1 kHz frequency on VACNF NEAs, showing distinct properties from macroscopic glassy carbon electrodes due to VACNF's unique interior structure. The enhanced ACV properties enable the kinetic measurements of proteolytic cleavage of the surface-attached tetrapeptides by proteases, further validated with a fluorescence assay. The data can be analyzed with a heterogeneous Michaelis-Menten model, giving "specificity constant" kcat /Km as (4.3 ± 0.8) × 10(4) M(-1)s(-1) for cathepsin B and (1.13 ± 0.38) × 10(4) M(-1)s(-1) for legumain. This method could be developed as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring. PMID:23814632

  11. Nonenzymatic hydrogen peroxide sensor based on a glassy carbon electrode modified with electrospun PdO-NiO composite nanofibers

    International Nuclear Information System (INIS)

    A glassy carbon electrode was modified with PdO-NiO composite nanofibers (PdO-NiO-NFs) and applied to the electrocatalytic reduction of hydrogen peroxide (H2O2). The PdO-NiO-NFs were synthesized by electrospinning and subsequent thermal treatment, and then characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Factors such as the composition and fraction of nanofibers, and of the applied potential were also studied. The sensor exhibits high sensitivity for H2O2 (583.43 ?A?·?mM?1?·?cm?2), a wide linear range (from 5.0 ?M to 19 mM), a low detection limit (2.94 ?M at an SNR of 3), good long term stability, and is resistant to fouling. (author)

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

    Directory of Open Access Journals (Sweden)

    Emel Yildiz

    2008-01-01

    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.

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

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; ?íha, Pavel; Olejník, J.; Ková?, M.; Svoboda, P.

    2013-01-01

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

  14. Characterization of carbon nanofiber electrode arrays using electrochemical impedance spectroscopy: effect of scaling down electrode size.

    Science.gov (United States)

    Siddiqui, Shabnam; Arumugam, Prabhu U; Chen, Hua; Li, Jun; Meyyappan, M

    2010-02-23

    We report here how the electrochemical impedance spectra change as (i) electrode size is reduced to nanometer scale and (ii) spacing between vertically aligned carbon nanofiber (VACNF) electrodes is varied. To study this, we used three types of electrodes: standard microdisks (100 microm Pt, 10 microm Au, and 7 microm glassy carbon), randomly grown (RG) VACNFs where spacing between electrodes is not fixed, and electron beam patterned VACNF nanoelectrode arrays (pNEAs) where electrode spacing is fixed at 1 microm. As the size of the microdisk electrode is reduced, the spectrum changed from a straight line to a semicircle accompanied by huge noise. Although a semicircle spectrum can directly indicate the electron transfer resistance (R(ct)) and thus is useful for biosensing applications, the noise from electrodes, particularly from those with diameters < or =10 microm, limits sensitivity. In the case of VACNFs, the electrode spacing controls the type of spectrum, that is, a straight line for RG VACNFs and a semicircle for pNEAs. In contrast to microdisks, pNEAs showed almost insignificant noise even at small perturbations (10 mV). Second, only pNEAs showed linearity as the amplitude of the sinusoidal signal was increased from 10 to 100 mV. The ability to apply large amplitudes reduces the stochastic errors, provides high stability, and improves signal-to-noise (S/N) ratio. This new class of nanoelectrochemical system using carbon pNEAs offers unique properties such as semicircle spectra that fit into simple circuits, high S/N ratio, linearity, and tailor-made spectra for specific applications by controlling electrode size, spacing, and array size. PMID:20099879

  15. Thin MoS2 nanoflakes encapsulated in carbon nanofibers as high-performance anodes for lithium-ion batteries.

    Science.gov (United States)

    Zhao, Chenyang; Kong, Junhua; Yao, Xiayin; Tang, Xiaosheng; Dong, Yuliang; Phua, Si Lei; Lu, Xuehong

    2014-05-14

    In this work, highly flexible MoS2-based lithium-ion battery anodes composed of disordered thin MoS2 nanoflakes encapsulated in amorphous carbon nanofibrous mats were fabricated for the first time through hydrothermal synthesis of graphene-like MoS2, followed by electrospinning and carbonization. X-ray diffraction as well as scanning and transmission electron microscopic studies show that the as-synthesized MoS2 nanoflakes have a thickness of about 5 nm with an expanded interlayer spacing, and their structure and morphology are well-retained after the electrospinning and carbonization. At relatively low MoS2 contents, the nanoflakes are dispersed and well-embedded in the carbon nanofibers. Consequently, excellent electrochemical performance, including good cyclability and high rate capacity, was achieved with the hybrid nanofibrous mat at the MoS2 content of 47%, which may be attributed to the fine thickness and multilayered structure of the MoS2 sheets with an expanded interlayer spacing, the good charge conduction provided by the high-aspect-ratio carbon nanofibers, and the robustness of the nanofibrous mat. PMID:24701987

  16. One-dimensionality of phonon transport in cup-stacked carbon nanofibers.

    Science.gov (United States)

    Ito, Y; Inoue, M; Takahashi, K

    2010-02-17

    We treat the ballistic heat conduction of cup-stacked carbon nanofibers (CSCNF) by a nonequilibrium molecular dynamics simulation. The CSCNF consist of numerous tiny graphene cups linked in line by weak intermolecular forces. The simulation results show that the thermal conductivity varies with the fiber length in a power law fashion with an exponent as large as 0.7. The calculated phonon density of states revealed that a low frequency oscillation in the radial and axial directions dominates the heat conduction in CSCNF. The atomic motions indicate that these low frequency oscillations are quasi-one-dimensional (1D) where each cup moves axially like a rigid body and radially with a breathing motion. This quasi-1D oscillation occurs due to the unique structure of a CSCNF that resembles a 1D harmonic chain. Our investigations show that treating a CSCNF as a 1D chain with three-dimensional oscillations explains why this material has the highest ballistic phonon transport ever observed. PMID:21389368

  17. Vertically aligned carbon nanofiber architecture as a multifunctional 3-D neural electrical interface.

    Science.gov (United States)

    Nguyen-Vu, T D Barbara; Chen, Hua; Cassell, Alan M; Andrews, Russell J; Meyyappan, M; Li, Jun

    2007-06-01

    Developing biomaterial constructs that closely mimic the natural tissue microenvironment with its complex chemical and physical cues is essential for improving the function and reliability of implantable devices, especially those that require direct neural-electrical interfaces. Here we demonstrate that free-standing vertically aligned carbon nanofiber (VACNF) arrays can be used as a multifunctional 3-D brush-like nanoengineered matrix that interpenetrates the neuronal network of PC12 cells. We found that PC12 neuron cells cultured on VACNF substrates can form extended neural network upon proper chemical and biochemical modifications. The soft 3-D VACNF architecture provides a new platform to fine-tune the topographical, mechanical, chemical, and electrical cues at subcellular nanoscale. This new biomaterial platform can be used for both fundamental studies of material-cell interactions and the development of chronically stable implantable neural devices. Micropatterned multiplex VACNF arrays can be selectively controlled by electrical and electrochemical methods to provide localized stimulation with extraordinary spatiotemporal resolution. Further development of this technology may potentially result in a highly multiplex closed-loop system with multifunctions for neuromodulation and neuroprostheses. PMID:17554831

  18. One-dimensionality of phonon transport in cup-stacked carbon nanofibers

    International Nuclear Information System (INIS)

    We treat the ballistic heat conduction of cup-stacked carbon nanofibers (CSCNF) by a nonequilibrium molecular dynamics simulation. The CSCNF consist of numerous tiny graphene cups linked in line by weak intermolecular forces. The simulation results show that the thermal conductivity varies with the fiber length in a power law fashion with an exponent as large as 0.7. The calculated phonon density of states revealed that a low frequency oscillation in the radial and axial directions dominates the heat conduction in CSCNF. The atomic motions indicate that these low frequency oscillations are quasi-one-dimensional (1D) where each cup moves axially like a rigid body and radially with a breathing motion. This quasi-1D oscillation occurs due to the unique structure of a CSCNF that resembles a 1D harmonic chain. Our investigations show that treating a CSCNF as a 1D chain with three-dimensional oscillations explains why this material has the highest ballistic phonon transport ever observed.

  19. 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

    2012-09-26

    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, k(cat)/K(m), of (2.1±0.1)×10(7) 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 19.1s. This electrochemical method can be potentially used as a label-free method for profiling enzyme activities in fast reactions. PMID:22935373

  20. Electrospun carbon nanofibers as low-cost counter electrode for dye-sensitized solar cells.

    Science.gov (United States)

    Joshi, Prakash; Zhang, Lifeng; Chen, Qiliang; Galipeau, David; Fong, Hao; Qiao, Qiquan

    2010-12-01

    Electrospun carbon nanofibers (ECNs) have been explored as an electrocatalyst and low-cost alternative to platinum (Pt) for triiodide reduction in dye-sensitized solar cells (DSCs). The results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements indicated that the ECN counter electrodes exhibited low charge-transfer resistance (Rct), large capacitance (C), and fast reaction rates for triiodide reduction. Although the efficiency (?) of ECN-based cells was slightly lower than that of Pt-based cells, their short circuit current density (Jsc) and open circuit voltage (Voc) were comparable. The ECN-based cells achieved an energy conversion efficiency (?) of 5.5 % under the AM 1.5 illumination at 100 mW cm(-2). The reason for lower cell performance using the ECN electrode was because of its lower fill factor (FF) than that of Pt-based cells, probably caused by high total series resistance (RStot) at ?15.5 ? cm2, which was larger than that of ?4.8 ? cm2 in the Pt-based devices. Simulated results showed that the fill factor (FF) and ? could be substantially improved by decreasing RStot, which might be achieved by using thinner and highly porous ECNs to reduce the thickness of the ECNs counter electrode. PMID:21073177

  1. Enhanced performance in dye-sensitized solar cells via carbon nanofibers-platinum composite counter electrodes.

    Science.gov (United States)

    Poudel, Prashant; Zhang, Lifeng; Joshi, Prakash; Venkatesan, Swaminathan; Fong, Hao; Qiao, Qiquan

    2012-08-01

    A composite counter electrode (CE) made of electrospun carbon nanofibers (ECNs) and platinum (Pt) nanoparticles has been demonstrated for the first time to improve the performance of dye-sensitized solar cells (DSCs). The new ECN-Pt composite CE exhibited a more efficient electro-catalytic performance with lower charge transfer resistance (R(ct)), larger surface area, and faster reaction rate than those of conventional Pt. It reduced the overall series resistance (R(se)), decreased dark saturation current density (J(0)) and increased shunt resistance (R(sh)) of the DSCs, thereby leading to a higher fill factor (FF) and larger open circuit voltage (V(oc)). The reduced electron transport resistance (R(s)) and faster charge transfer rate in the CE led to a smaller overall cell series resistance (R(se)) in the ECN-Pt composite based DSCs. The DSCs based on an ECN-Pt CE achieved a ? of ?8%, which was improved over those of pure Pt or ECN based cells. PMID:22743819

  2. 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

  3. Monolithically Integrated, Mechanically Resilient Carbon-Based Probes for Scanning Probe Microscopy

    Science.gov (United States)

    Kaul, Anupama B.; Megerian, Krikor G.; Jennings, Andrew T.; Greer, Julia R.

    2010-01-01

    Scanning probe microscopy (SPM) is an important tool for performing measurements at the nanoscale in imaging bacteria or proteins in biology, as well as in the electronics industry. An essential element of SPM is a sharp, stable tip that possesses a small radius of curvature to enhance spatial resolution. Existing techniques for forming such tips are not ideal. High-aspect-ratio, monolithically integrated, as-grown carbon nanofibers (CNFs) have been formed that show promise for SPM applications by overcoming the limitations present in wet chemical and separate substrate etching processes.

  4. Electrospun Polyamide 6/Poly(allylamine hydrochloride) Nanofibers Functionalized with Carbon Nanotubes for Electrochemical Detection of Dopamine.

    Science.gov (United States)

    Mercante, Luiza A; Pavinatto, Adriana; Iwaki, Leonardo E O; Scagion, Vanessa P; Zucolotto, Valtencir; Oliveira, Osvaldo N; Mattoso, Luiz H C; Correa, Daniel S

    2015-03-01

    The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 ?mol L(-1), with detection limit of 0.15 ?mol L(-1) (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors. PMID:25644325

  5. Optimized electrospinning synthesis of iron-nitrogen-carbon nanofibers for high electrocatalysis of oxygen reduction in alkaline medium.

    Science.gov (United States)

    Yan, Xingxu; Liu, Kexi; Wang, Xiangqing; Wang, Tuo; Luo, Jun; Zhu, Jing

    2015-04-24

    To achieve iron-nitrogen-carbon (Fe-N-C) nanofibers with excellent electrocatalysis for replacing high-cost Pt-based catalysts in the cathodes of fuel cells and metal-air batteries, we have investigated and evaluated the effects of polyacrylonitrile (PAN) concentration and the proportion of iron to PAN, along with voltage and flow rate during the electrospinning process, and thus proposed three criteria to optimize these parameters for ideal nanofiber catalysts. The best half-wave potential of an optimized catalysts is 0.82 V versus reversible hydrogen electrode in an alkaline medium, which reaches the best range of the non-precious-metal catalysts reported and is very close to that of commercial Pt/C catalysts. Furthermore, the electron-transfer number of our catalysts is superior to that of the Pt/C, indicating the catalysts undergo a four-electron process. The durability of the optimized Fe-N-C nanofibers is also better than that of the Pt/C, which is attributed to the homogeneous distribution of the active sites in our catalysts. PMID:25815586

  6. Synthesis of ruthenium oxide coated ordered mesoporous carbon nanofiber arrays as a catalyst for lithium oxygen battery

    Science.gov (United States)

    Guo, Ziyang; Zhou, Dandan; Liu, Haijing; Dong, Xiaoli; Yuan, Shouyi; Yu, Aishui; Wang, Yonggang; Xia, Yongyao

    2015-02-01

    Li-O2 batteries with super-high theoretical energy density are attracting extensive attention. However, the sluggish oxygen reduction/evolution reaction, the huge volume change from O2/Li2O2 conversion and the undesired electrolyte decomposition in cathode limit their performance. Herein we show design and synthesis of RuO2-coated ordered mesoporous carbon nanofiber arrays by using a natural crab shell template as a catalyst for Li-O2 battery, exhibiting several advantage features. First, the ordered mesopores in nanofibers facilitate electrolyte penetration and electron/ion transfer. In addition, the macro-sized voids between the nanofibers provide efficient buffer space for O2/Li2O2 accommodation and improve O2 diffusion. Furthermore, the uniform RuO2-coating layer alleviates undesired electrolyte decomposition and enhances the surface electronic conductivity. As a result, the battery displays high performance, including high capacity (20600 mAh g-1 at a current density of 100 mA g-1), high rate (9750 mAh g-1 at a current density of 1000 mA g-1) and long-life (300 cycles at a fixed capacity of 1000 mAh g-1).

  7. Preparation and characterization of electrospun core sheath nanofibers from multi-walled carbon nanotubes and poly(vinyl pyrrolidone).

    Science.gov (United States)

    Miao, Jianjun; Miyauchi, Minoru; Dordick, Jonathan S; Linhardt, Robert J

    2012-03-01

    Electrospinning is a versatile technique to prepare polymer fibers in nano to micrometer size ranges using very high electrostatic fields. Electrospun nanofibers with tunable porosity and high specific surface area have various applications, including chromatographic supports for protein separation, biomedical devices, tissue engineering and drug delivery matrices, and as key components in solar cells and supercapacitors. Unspinnable materials such as nanoparticles, nanorods, nanotubes or rigid conducting polymers can also be electrospun into fibers through co-axial electrospinning. In this study, we have prepared core-sheath nanofibers utilizing co-axial electrospinning. The core portion of these electrospun fibers consists of multi-walled carbon nanotubes and the sheath portion is poly(vinyl pyrrolidone) (PVP). Various morphologies were obtained by changing both core and sheath solution concentrations. The core-sheath nanofibers were characterized by scanning electron microscopy and transmission electron microscopy, to confirm core-sheath morphology, thermogravimetric analysis, and mechanical strength testing. The electrical conductivity of the surfaces of poly(vinyl pyrrolidone) fibers and poly(vinyl pyrrolidone)-multi-walled nanotube fibers were both 10(-15) S/m. The highest bulk conductivity observed for the poly(vinyl pyrrolidone)-multi-walled nanotube fibers was 1.2 x 10(-3) S/m. PMID:22755063

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

    Directory of Open Access Journals (Sweden)

    G. R. Rakesh

    2015-02-01

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

  9. Li2MnSiO4/Carbon Composite Nanofibers as a High-Capacity Cathode Material for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xiangwu Zhang

    2012-06-01

    Full Text Available Li2MnSiO4 has an extremely high theoretical capacity of 332 mAh?g?1. However, only around half of this capacity has been realized in practice and the capacity retention during cycling is also low. In this study, Li2MnSiO4/carbon composite nanofibers were prepared by a combination of electrospinning and heat treatment. The one-dimensional continuous carbon nanofiber matrix serves as long-distance conductive pathways for both electrons and ions. The composite nanofiber structure avoids the aggregation of Li2MnSiO4 particles, which in turn enhances the electrode conductivity and promotes the reaction kinetics. The resultant Li2MnSiO4/carbon composite nanofibers were used as the cathode material for Li-ion batteries, and they delivered high charge and discharge capacities of 218 and 185 mAh?g?1, respectively, at the second cycle. In addition, the capacity retention of Li2MnSiO4 at the first 20th cycles increased from 37% to 54% in composite nanofibers.

  10. Ecotoxicological effects of carbon nanotubes and cellulose nanofibers in Chlorella vulgaris

    Science.gov (United States)

    2014-01-01

    Background MWCNT and CNF are interesting NPs that possess great potential for applications in various fields such as water treatment, reinforcement materials and medical devices. However, the rapid dissemination of NPs can impact the environment and in the human health. Thus, the aim of this study was to evaluate the MWCNT and cotton CNF toxicological effects on freshwater green microalgae Chlorella vulgaris. Results Exposure to MWCNT and cotton CNF led to reductions on algal growth and cell viability. NP exposure induced reactive oxygen species (ROS) production and a decreased of intracellular ATP levels. Addition of NPs further induced ultrastructural cell damage. MWCNTs penetrate the cell membrane and individual MWCNTs are seen in the cytoplasm while no evidence of cotton CNFs was found inside the cells. Cellular uptake of MWCNT was observed in algae cells cultured in BB medium, but cells cultured in Seine river water did not internalize MWCNTs. Conclusions Under the conditions tested, such results confirmed that exposure to MWCNTs and to cotton CNFs affects cell viability and algal growth. PMID:24750641

  11. CVD growth of carbon nanostructures from zirconia: mechanisms and a method for enhancing yield.

    Science.gov (United States)

    Kudo, Akira; Steiner, Stephen A; Bayer, Bernhard C; Kidambi, Piran R; Hofmann, Stephan; Strano, Michael S; Wardle, Brian L

    2014-12-24

    By excluding metals from synthesis, growth of carbon nanostructures via unreduced oxide nanoparticle catalysts offers wide technological potential. We report new observations of the mechanisms underlying chemical vapor deposition (CVD) growth of fibrous carbon nanostructures from zirconia nanoparticles. Transmission electron microscope (TEM) observation reveals distinct differences in morphological features of carbon nanotubes and nanofibers (CNTs and CNFs) grown from zirconia nanoparticle catalysts versus typical oxide-supported metal nanoparticle catalysts. Nanofibers borne from zirconia lack an observable graphitic cage consistently found with nanotube-bearing metal nanoparticle catalysts. We observe two distinct growth modalities for zirconia: (1) turbostratic CNTs 2-3 times smaller in diameter than the nanoparticle localized at a nanoparticle corner, and (2) nonhollow CNFs with approximately the same diameter as the nanoparticle. Unlike metal nanoparticle catalysts, zirconia-based growth should proceed via surface-bound kinetics, and we propose a growth model where initiation occurs at nanoparticle corners. Utilizing these mechanistic insights, we further demonstrate that preannealing of zirconia nanoparticles with a solid-state amorphous carbon substrate enhances growth yield. PMID:25487041

  12. 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. PMID:25372400

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

    International Nuclear Information System (INIS)

    Highlights: ? TiO2/multi-walled carbon nanotubes (MWCNTs) hybrid nanofibers are prepared via electrospinning. ? Dye-sensitized solar cells (DSSCs) are assembled using TiO2/MWCNTs nanofibers film as photoanode. ? Energy conversion efficiency of DSSCs is greatly dependent on the content of MWCNTs. ? Moderate MWCNTs incorporation can substantially enhance the performance of DSSCs. - Abstract: Anatase TiO2/multi-walled carbon nanotubes (TiO2/MWCNTs) hybrid nanofibers (NFs) film was prepared via a facile electrospinning method. Dye-sensitized solar cells (DSSCs) based on TiO2/MWCNTs composite NFs photoanodes with different contents of MWCNTs (0, 0.1, 0.3, 0.5, 1 wt.%) were assembled using N719 dye as sensitizer. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Raman spectrometer were used to characterize the TiO2/MWCNTs electrode films. The photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate the photoelectric properties of the DSSCs. The results reveal that the energy conversion efficiency is greatly dependent on the content of MWCNTs in the composite NFs film, and a moderate incorporation of MWCNTs can substantially enhance the performance of DSSCs. When the electrode containss. When the electrode contains 0.3 wt.% MWCNTs, the corresponding solar cell yield the highest efficiency of 5.63%. This efficiency value is approximately 26% larger than that of the unmodified counterpart.

  14. Carbon nanotubes and nanofibers synthesized by CVD on nickel coatings deposited with a vacuum arc

    International Nuclear Information System (INIS)

    Nanotubes and nanofibers were grown on Ni coatings deposited by plasma generated with a pulsed vacuum arc on silicon wafers using three different bias conditions: at floating potential (approximately +30 V respect to the grounded cathode); at ground potential; and at -60 V. An atomic force microscopy study showed that the Ni film morphology was affected by the bias condition of the substrate. The morphology of carbonaceous species depended on Ni-films characteristics. FE-SEM and TEM analyses have shown that nanofibers growth was favoured on Ni coatings deposited at -60 V whereas nanotubes grew mainly on Ni coatings obtained at floating and ground potentials. Hence, this new method to produce the precursor can be optimized to obtain nanotubes or nanofibers varying the substrate bias for the Ni deposition.

  15. Processing, wear, and mechanical properties of polyethylene composites prepared with pristine and organosilane-treated carbon nanofibers

    Science.gov (United States)

    Wood, Weston

    Polymers and nanocomposites have been increasingly used for tribological applications over the last few decades. In particular, ultrahigh molecular weight polyethylene (UHMWPE) is a high performance polymer with excellent strength, toughness, and wear resistance. Because of these properties, UHMWPE is an ideal material for a variety of applications including body armor, components of sporting goods such as skies and snowboards, and liners in total joint replacement. Though the toughness and wear resistance far exceed that of most other polymeric materials, there is a high demand for improving the tribological and mechanical properties of UHMWPE for many applications. The approach used in this work for improving such properties is through nanocomposite technology, specifically via the incorporation of carbon nanofibers. In order to obtain the full potential of nanocomposite technology, two critical issues need to be addressed: appropriate interactions between the filler and matrix and proper dispersion of the nano-reinforcement. These critical issues are particularly important for UHMWPE nanocomposites in that UHMWPE is an extremely viscous polymer and thus cannot be processed conventionally, typically resulting in dispersion issues far worse than that of other composite systems. Furthermore, UHMWPE is non-polar, so interactions between filler and matrix will be limited to Van der Waals forces for untreated nanofillers. Therefore, the research presented aims at solving these issues by using a paraffin-assisted processing method and applying appropriate surface treatment to the carbon nanofibers. Under optimized processing conditions, wear and mechanical properties of UHMWPE composites can be substantially improved.

  16. Reversible Hydrogen Storage in Electrospun Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Haji A.

    2013-09-01

    Full Text Available Composite nanofibers containing single-walled carbon nanotubes (SWNT were prepared by using electrospinning technique and hydrogen adsorption/desorption isotherms were carried out by a Sieverts apparatus at room temperature. The SEM analysis of the nanofibers revealed that the deformation of the nanofiber increases with increasing SWNT concentration. The diameter of neat nanofibers was below 200 nm and had smooth surface. The surface of the composite nanofibers was rough even by adding low quantity of SWNT. The hydrogen storage results showed an improvement in the adsorption capacity with increasing the SWNT content in composite nanofibers. These nanofibers were evacuated again to remove the adsorbed hydrogen at room temperature. Moreover, even though specific surface area and total pore volume were important factors for increasing the capacity of hydrogen adsorption. Finally, maximum adsorption capacity was 0.29 wt % in case of nanofibers with 10 wt % SWNT under 30 bar at 298 K.

  17. Electrospun highly ordered mesoporous silica-carbon composite nanofibers for rapid extraction and prefractionation of endogenous peptides.

    Science.gov (United States)

    Zhu, Gang-Tian; Chen, Xi; He, Xiao-Mei; Wang, Han; Zhang, Zheng; Feng, Yu-Qi

    2015-03-01

    A simple method was developed for the preparation of ordered mesoporous silica-carbon composite nanofibers (OMSCFs). The OMSCFs exhibited high carbon content, continuously long fibrous properties, uniform accessible mesopores, and a large surface area. The OMSCFs were also found to have ion-exchange capacity. On the basis of the size-exclusion effect of the mesopores and mixed-mode hydrophobic/ion-exchange interactions, the OMSCFs were applied for rapid enrichment of endogenous peptides by using a miniaturized solid-phase extraction format. The adsorption mechanism was studied, and the eluting solution was optimized with standard peptide/protein solutions and protein digests. Employing a successive three-step elution strategy, followed by LC-MS/MS analysis, led to excellent performance with this approach in the extraction and prefractionation of peptides from human serum. PMID:25641232

  18. 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

  19. Viscoelastic characterization of vapor-grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology

    Science.gov (United States)

    Drake, Daniel Adam

    The effects of vapor-grown carbon nanofiber (VGCNF) weight fraction, applied stress, and temperature on the viscoelastic responses (creep strain, creep rate, and creep compliance) of VGCNF/vinyl ester (VE) nanocomposites were studied using a central composite design (CCD). The nanocomposite test articles were fabricated by high shear mixing, casting, curing, and post-curing in an open face mold under a nitrogen environment. Short-term creep/creep recovery experiments were conducted at prescribed combinations of temperatures (23.8 - 69.2 C), applied stresses (30.2 - 49.8 MPa), and VGCNF weight fractions (0.00 - 1.00 parts of VGCNF per hundred parts of resin, phr) determined from the CCD. The response surface models (RSMs) for predicting these viscoelastic responses were developed using the least squares method and an analysis of variance procedure. The response surface estimates indicate that increasing the VGCNF weight fraction marginally increases the creep resistance of the VGCNF/VE nanocomposite at low temperatures (i.e., 23.8 - 46.5 C). However, increasing the VGCNF weight fraction for temperatures greater than 50 C decreased the creep resistance of these nanocomposites. The latter response may be due to a decrease in the nanofiber-to-matrix adhesion as the temperature is increased. The RSMs for creep strain, creep rate, and creep compliance revealed the interactions between the VGCNF weight fraction, stress, and temperature on the creep behavior of thermoset polymer.

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

    Science.gov (United States)

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

    2014-11-15

    A new biosensing platform based on electrospun carbon nanotubes nanofibers (CNTs@PNFs) composite, which enabled strong electrochemiluminescent emission of peroxydisulfate, was firstly developed for immunoassay with favorable analytical performances, and then was utilized to evaluate the interaction between antibody and antigen in vitro. Moreover, the obvious ECL image of peroxydisulfate on the prepared sensing platform was firstly recorded in this report. In order to expand the application of peroxydisulfate ECL, the specific recognization biomolecules, ?-fetoprotein (AFP) antibody was bound to the functionalized film via electrostatic interaction for fabricating label-free ECL immunosensor to detect ?-AFP. Based on the ECL change resulting from the specific immunoreaction between antigen and antibody, the quantitative analysis for AFP with wide dynamic response in the range from 0.1 pg mL(-1) to 160 ng mL(-1) was realized. And the limit of detection was estimated to be 0.09 pg mL(-1). Therefore, the flexible sensing platform not only acted as the sensitized sensing element, but also offered a suitable carrier for immobilization of biological recognition elements with low-toxicity and eco-friendliness, which opened a promising approach to developing further electrospun nanofiber based amplified ECL biosensor with favorable analytical performances. PMID:24953845

  1. 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

  2. Centrifugal spinning: A novel approach to fabricate porous carbon fibers as binder-free electrodes for electric double-layer capacitors

    Science.gov (United States)

    Lu, Yao; Fu, Kun; Zhang, Shu; Li, Ying; Chen, Chen; Zhu, Jiadeng; Yanilmaz, Meltem; Dirican, Mahmut; Zhang, Xiangwu

    2015-01-01

    Carbon nanofibers (CNFs), among various carbonaceous candidates for electric double-layer capacitor (EDLC) electrodes, draw extensive attention because their one-dimensional architecture offers both shortened electron pathways and high ion-accessible sites. Creating porous structures on CNFs yields larger surface area and enhanced capacitive performance. Herein, porous carbon nanofibers (PCNFs) were synthesized via centrifugal spinning of polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) solutions combined with thermal treatment and were used as binder-free EDLC electrodes. Three precursor fibers with PAN/PMMA weight ratios of 9/1, 7/3 and 5/5 were prepared and carbonized at 700, 800, and 900 °C, respectively. The highest specific capacitance obtained was 144 F g-1 at 0.1 A g-1 with a rate capability of 74% from 0.1 to 2 A g-1 by PCNFs prepared with PAN/PMMA weight ratio of 7/3 at 900 °C. These PCNFs also showed stable cycling performance. The present work demonstrates that PCNFs are promising EDLC electrode candidate and centrifugal spinning offers a simple, cost-effective strategy to produce PCNFs.

  3. Simple preparation of carbon nanofibers with graphene layers perpendicular to the length direction and the excellent li-ion storage performance.

    Science.gov (United States)

    Li, Tao; Wei, Cheng; Wu, Yi-Min; Han, Fu-Dong; Qi, Yong-Xin; Zhu, Hui-Ling; Lun, Ning; Bai, Yu-Jun

    2015-03-11

    Sulfur-containing carbon nanofibers with the graphene layers approximately vertical to the fiber axis were prepared by a simple reaction between thiophene and sulfur at 550 °C in stainless steel autoclaves without using any templates. The formation mechanism was discussed briefly, and the potential application as anode material for lithium-ion batteries was tentatively investigated. The carbon nanofibers exhibit a stable reversible capacity of 676.8 mAh/g after cycling 50 times at 0.1 C, as well as the capacities of 623.5, 463.2, and 365.8 mAh/g at 0.1, 0.5, and 1.0 C, respectively. The excellent electrochemical performance could be attributed to the effect of sulfur. On one hand, sulfur could improve the reversible capacity of carbon materials due to its high theoretical capacity; on the other hand, sulfur could promote the formation of the unique carbon nanofibers with the graphene layers perpendicular to the axis direction, favorable to shortening the Li-ion diffusion path. PMID:25706088

  4. Towards the control of the diameter of individualized single walled carbon nanotubes in CVD process at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tsareva, Svetlana [Institut Jean Lamour UMR 7819, CNRS - Universite de Lorraine, Parc de Saurupt, 54011 Nancy (France); Structure et Reactivite des Systemes Moleculaires Complexes UMR 7565, CNRS - Universite de Lorraine, Vandoeuvre les Nancy (France); Devaux, Xavier [Institut Jean Lamour UMR 7819, CNRS - Universite de Lorraine, Parc de Saurupt, 54011 Nancy (France); Dossot, Manuel [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement UMR 7564, CNRS - Universite de Lorraine, 54602 Villers les Nancy (France)

    2012-12-15

    In the current work, we show that it is possible to favor the selective growth of single-walled carbon nanotubes (SWCNTs) with a narrow diameter distribution on supported catalyst particles with a broad size distribution. Carbon nanotubes were grown at 600 C on silicon substrates. The structure of carbon deposits was controlled by managing the carbon feedstock for adjusting the rate of carbon nanostructures formation on the surface of catalyst particles. Either carbon nanofibers (CNFs) carpets or isolated SWCNTs were obtained. With the fine tune of carbon feedstock, small isolated SWCNTs with a narrow diameter distribution were obtained by limiting the catalytic activity of the largest catalyst particles. HRTEM observations of nanotube embryos have suggested a possible mechanism of multi-walled carbon nanotubes (MWCNTs) formation that can explain why the growth of MWCNTs with parallel walls seems to be more difficult than SWCNTs or CNFs at low temperature. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Engineered magnetic core-shell SiO2/Fe microspheres and "medusa-like" microspheres of SiO2/iron oxide/carbon nanofibers or nanotubes.

    Science.gov (United States)

    Mero, On; Sougrati, Moulay-Tahar; Jumas, Jean-Claude; Margel, Shlomo

    2014-08-19

    Iron oxide (IO) thin coatings of controlled thickness on SiO2 microspheres of narrow size distribution were prepared by decomposition at 160 °C of triiron dodecacarbonyl onto silica microspheres dispersed in diethylene glycol diethyl ether free of surfactant or stabilizer. The dried washed SiO2/IO core-shell microspheres were annealed at different temperatures and time periods under inert (Ar) or reducing (H2) atmosphere. The effect of temperature on the chemical composition, morphology, crystallinity, and magnetic properties of the IO and the elemental Fe nanoparticles type coatings onto the SiO2 core microspheres has been elucidated. "Medusa-like" SiO2/IO/carbon nanofibers and tubes particles were prepared by CVD of ethylene on the surface of the SiO2/IO microspheres at different temperatures. The morphology change of the grafted carbon nanofibers and tubes as a function of the CVD temperature was also elucidated. PMID:25089849

  6. Preparation and electrochemical performance of hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets for a battery-supercapacitor hybrid system.

    Science.gov (United States)

    Choi, Hong Soo; Kim, TaeHoon; Im, Ji Hyuk; Park, Chong Rae

    2011-10-01

    Hyper-networked Li(4)Ti(5)O(12)/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li(4)Ti(5)O(12), and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li(4)Ti(5)O(12)/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g(-1) at 4000 mA g(-1) as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg(-1) and 22 W kg(-1) at power densities of 50 W kg(-1) and 4000 W kg(-1), respectively, which are superior to the values observed for the AC [symbol: see text] AC symmetric electrode system. PMID:21911931

  7. Preparation and electrochemical performance of hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets for a battery-supercapacitor hybrid system

    Science.gov (United States)

    Choi, Hong Soo; Kim, TaeHoon; Im, Ji Hyuk; Park, Chong Rae

    2011-10-01

    Hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li4Ti5O12, and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li4Ti5O12/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g - 1 at 4000 mA g - 1 as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg - 1 and 22 W kg - 1 at power densities of 50 W kg - 1 and 4000 W kg - 1, respectively, which are superior to the values observed for the {AC} \\parallel {AC} symmetric electrode system.

  8. Preparation and electrochemical performance of hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets for a battery-supercapacitor hybrid system

    International Nuclear Information System (INIS)

    Hyper-networked Li4Ti5O12/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li4Ti5O12, and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li4Ti5O12/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g-1 at 4000 mA g-1 as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg-1 and 22 W kg-1 at power densities of 50 W kg-1at power densities of 50 W kg-1 and 4000 W kg-1, respectively, which are superior to the values observed for the AC||AC symmetric electrode system.

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

    International Nuclear Information System (INIS)

    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 H2O2, a product from the reduction of O2 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 H2O2 under a relatively negative potential. The resulting glucose biosensor exhibited a rapid response of 5 s, a low detection limit of 0.5 ?M, a wide linear range of 0.02–12 mM, a high sensitivity of 35.94 ?A cm?2 mM?1, as well as good stability, repeatability and selectivity. The sensor might be promising for practical application. (paper)

  10. In situ fabrication of Ni(OH)2 nanofibers on polypyrrole-based carbon nanotubes for high-capacitance supercapacitors

    International Nuclear Information System (INIS)

    Highlights: ? Facile surface decoration approach to highly porous Ni(OH)2/CNT composites. ? Polypyrrole-based CNTs form three-dimensional electron-transport channels. ? A high capacitance of 1118 F g?1 at 50 mA cm?2 is delivered. ? Ni(OH)2/CNT composites exhibit high discharge capability. - Abstract: Large-scale nickel hydroxide–carbon [Ni(OH)2/CNT] networks with three-dimensional electron-transport channels are synthesized via a facile and general surface-decoration approach, using polypyrrole-derived CNTs as the support. Flexible Ni(OH)2 nanofibers with a diameter of 5–10 nm and a length of 50–120 nm are intertwined and wrapped homogenously on carbon networks, leading to the formation of more complex networks. When used as supercapacitor electrodes, this designed architecture with large surface area, abundant pores and good electrical conductivity is very important in technology. It can promote the bulk accessibility of electrolyte OH? and diffusion rate within the redox phase. Consequently, an unusual specific capacitance of 1745 F g?1 can be obtained for Ni(OH)2/CNT composite at 30 mA cm?2. Even at a high rate (50 mA cm?2), the composite can also deliver a specific capacitance as high as 1118 F g?1, exhibiting the potential application for supercapacitors

  11. Structure and Mechanical Behavior of Cellulose Nanofiber and Micro-Fibrils by Molecular Dynamics Simulation

    OpenAIRE

    Ken-ichi Saitoh; Haruhiko Ohno; Syunichiro Matsuo

    2013-01-01

    Cellulose nanofiber (CNF) and CNF micro-fibrils (CNF-MFs) are computationally modeled by molecular dynamics with united atom (UA) methodology of polymers. Structural stability and mechanical properties of these materials are focused on. Diffusion coefficient decreases with increase of the number of shells in CNF-MF. The structure of CNF-MFs with crystalline alignment is totally stabilized with twist which is an accumulation of torsion angles at Glycosidic bonds between monomers inside CNFs. ...

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

    Science.gov (United States)

    Mann, Erin

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

  13. 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 responses to carbonaceous fibrous nanoparticles. Therefore, they could be useful dose metrics for risk assessment and management.

  14. A novel electrochemical sensor of bisphenol A based on stacked graphene nanofibers/gold nanoparticles composite modified glassy carbon electrode

    International Nuclear Information System (INIS)

    In this paper, a novel and convenient electrochemical sensor based on stacked graphene nanofibers (SGNF) and gold nanoparticles (AuNPs) composite modified glassy carbon electrode (GCE) was developed for the determination of bisphenol A (BPA). The AuNPs/SGNF modified electrode showed an efficient electrocatalytic role for the oxidation of BPA, and the oxidation overpotentials of BPA were decreased significantly and the peak current increased greatly compared with bare GCE and other modified electrode. The transfer electron number (n) and the charge transfer coefficient (?) were calculated with the result as n = 4, ? = 0.52 for BPA, which indicated the electrochemical oxidation of BPA on AuNPs/SGNF modified electrode was a four-electron and four-proton process. The effective surface areas of AuNPs/SGNF/GCE increased for about 1.7-fold larger than that of the bare GCE. In addition, the kinetic parameters of the modified electrode were calculated and the apparent heterogeneous electron transfer rate constant (ks) was 0.51 s?1. Linear sweep voltammetry was applied as a sensitive analytical method for the determination of BPA and a good linear relationship between the peak current and BPA concentration was obtained in the range from 0.08 to 250 ?M with a detection limit of 3.5 × 10?8 M. The modified electrode exhibited a high sensitivity, long-term stability and remarkable reproducible analytical performance and was successfully applied for the determination of BPA in baby bottles with satisfying results

  15. Early Combination of Material Characteristics and Toxicology Is Useful in the Design of Low Toxicity Carbon Nanofiber

    Directory of Open Access Journals (Sweden)

    Tore Syversen

    2012-09-01

    Full Text Available This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product.

  16. Synthesis and properties of SiN coatings as stable fluorescent markers on vertically aligned carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, Ryan [North Carolina State University; Klein, Kate L [ORNL; Ivanov, Ilia N [ORNL; Hensley, Dale K [ORNL; Meyer III, Harry M [ORNL; Melechko, Anatoli [North Carolina State University; McKnight, Timothy E [ORNL

    2014-01-01

    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 mostly Si and N. In fluorescent microscopy experiments, imaging VACNF interfacing to live cell cultures it turned out that this material is broadly fluorescent, which made VACNFs useful as spatial markers, or created nuisance when DNA-labeling got masked. In this paper we provide insight into nature of this silicon/nitrogen in situ coatings. Here we have proposed a potential mechanism for deposition of SiNx coating on the sidewalls of VACNFs during PECVD synthesis in addition to exploring the origin of the coatings fluorescence. It seems most likely that the substrate reacts with the process gases through both processes similar to reactive sputtering and CVD to form silane and other silicon bearing compounds before being deposited isotropically as a SiNx coating onto the VACNFs. The case for the presence of Si-NCs is made strong through a combination of the strong fluorescence and elemental analysis of the samples. These broadly luminescent fibers can prove useful as registry markers in fluorescent cellular studies.

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

    Science.gov (United States)

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

    2014-06-15

    The proteolytic activity of a cancer-related enzyme cathepsin B is measured with alternating current voltammetry (ACV) using ferrocene (Fc) labeled tetrapeptides attached to nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). This combination enables the use of high AC frequencies (~1kHz) with enhanced electrochemical signals. The specific proteolysis of the Fc-peptide by cathepsin B produces decay in the ACV peak current versus the reaction time. The exponential component of the raw data can be extracted and defined as the "extracted proteolytic signal" which allows consistent quantitative analyses using a heterogeneous Michaelis-Menten model. A "specificity constant" kcat/KM = (3.68 ± 0.50) × 10(4)M(-1)s(-1) for purified cathepsin B was obtained. The detections of cathepsin B activity in different concentrations of whole lysate of human breast tissue, tissue lysate spiked with varied concentrations of cathepsin B, and the tissue lysate after immunoprecipitation showed that there is ~13.4 nM higher cathepsin B concentration in 29.1 µg mL(-1) of whole tissue lysate than the immunoprecipitated sample. The well-defined regular VACNF NEAs by e-beam lithography show a much faster kinetics for cathepsin B proteolysis with kcat/KM = 9.2 × 10(4)M(-1)s(-1). These results illustrate the potential of this technique as a portable multiplex electronic system for cancer diagnosis by rapid protease profiling of serum or blood samples. PMID:24480132

  18. A simple synthesis of hollow carbon nanofiber-sulfur composite via mixed-solvent process for lithium-sulfur batteries

    Science.gov (United States)

    Li, Qiang; Zhang, Zhian; Zhang, Kai; Fang, Jing; Lai, Yanqing; Li, Jie

    2014-06-01

    A hollow carbon nanofiber supported sulfur (HCNF-S) composite cathode material is prepared by a mixed-solvent (DMF/CS2) process in an organic solution for lithium-sulfur batteries. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show the hollow structures of the HCNF and the homogeneous distribution of sulfur in the composite. The performance of the HCNF-S cathode is evaluated in lithium-sulfur batteries using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. It is found that the HCNF-S cathode shows perfect cycling stability. The results exhibit an initial discharge capacity of 1090 mAh g-1 and retains 600 mAh g-1 after 100 discharge/charge cycles at a high rate of 1 C. The excellent electrochemical properties benefit from the hollow and highly conductive network-like structure of HCNFs, which contribute to disperse sulfur and absorb polysulfides, and suppress the formation of residual Li2S layer.

  19. 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

  20. A novel and simple route to prepare a Pt nanoparticle-loaded carbon nanofiber electrode for hydrogen peroxide sensing.

    Science.gov (United States)

    Liu, Yang; Wang, Dawei; Xu, Lei; Hou, Haoqing; You, Tianyan

    2011-07-15

    A facile wet-chemical method was developed to prepare a novel Pt nanoparticle-loaded carbon nanofiber (Pt/CNF) electrode. Without using any stabilizer or pretreatment procedure, large amounts of Pt nanoparticles could be well deposited on the surface of the electrospun CNF electrode at room temperature, as revealed by scanning electron microscopy (SEM). The effect of the precursor concentration on the formation of Pt catalysts was investigated to optimize the performance of the proposed hybrid electrode. When applied to the electrochemical detection of hydrogen peroxide (H?O?), the Pt/CNF electrode exhibited low overpotential, fast response and high sensitivity. A low detection limit of 0.6 ?M with wide linear range of 1-800 ?M (R=0.9991) was achieved at the Pt/CNF electrode, which was superior to that obtained with other H?O? electrochemical sensors reported previously. In addition, the Pt/CNF electrode showed good selectivity for H?O? detection in the presence of ascorbic acid (AA), acetaminophenol (AP) and uric acid (UA) under physiological pH condition. The attractive analytical performances and facile preparation method made this novel hybrid electrode promising for the development of effective H?O? sensors. PMID:21665458

  1. Magnetic amphiphilic composites based on carbon nanotubes and nanofibers grown on an inorganic matrix: effect on water-oil interfaces

    Scientific Electronic Library Online (English)

    Aline A. S., Oliveira; Ivo F., Teixeira; Leandro P., Ribeiro; Juliana C., Tristão; Anderson, Dias; Rochel M., Lago.

    2184-21-01

    Full Text Available Novos compósitos magnéticos anfifílicos foram preparados pelo crescimento de nanotubos e nanofibras de carbono contendo partículas magnéticas através de deposição química de vapor (CVD), utilizando etanol como fonte de carbono e lama vermelha (RM, subproduto do processo Bayer de produção de alumina) [...] como suporte e catalisador. Monitoramento da reação CVD à temperatura programada (TPCVD), difração de raios X (XRD), espectroscopia Mössbauer, espectroscopia de energia dispersiva (EDS), espectroscopia Raman, termogravimetria (TG/DTA), análise elementar (CHN), determinação de área superficial (BET), microscopia eletrônica de varredura (SEM) e de transmissão (TEM) e medidas magnéticas mostraram que etanol reduz íons de ferro na RM para formar fases magnéticas, por exemplo Fe3O4 e Fe0, e depósitos de carbono (5-42 wt.%) na forma de nanotubos e nanofibras. A combinação de nanoestruturas hidrofóbicas de carbono com óxidos hidrofílicos de Al, Si e Ti presentes na lama vermelha produziu materiais anfifílicos com excelente interação com a interface água-óleo. Misturas de óleo de soja ou de decalina com água (completamente imiscíveis) foram emulsificadas facilmente na presença dos compósitos anfifílicos. Quando os compósitos foram adicionados a uma emulsão água-biodiesel estável, as partículas anfifílicas difundiram-se para a interface água- óleo. As partículas do compósito foram atraídas por ímãs e carregaram com elas as gotas de óleo, levando à completa desemulsificação e separação entre biodiesel e água. Abstract in english New magnetic amphiphilic composites were prepared by the catalytic carbon vapor deposition (CVD) growth of carbon nanotubes and nanofibers using ethanol as carbon source and red mud waste (RM, a by-product of the Bayer process of alumina production) as catalyst and support. Temperature-programmed CV [...] D (TPCVD), analyses by X-ray diffractometry (XRD), Mössbauer spectroscopy, energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, thermogravimetry (TG/DTA), elemental analysis (CHN), superficial area determination (BET), scanning (SEM) and transmission (TEM) electron microscopies and magnetic measurements showed that ethanol reduces the iron ions in the red mud to form magnetic phases, e.g., Fe3O4 and Fe0, and carbon deposits (5-42 wt.%), particularly nanotubes and nanofibers. The combination of the hydrophobic carbon nanostructures with the hydrophilic Al, Si and Ti oxides present in the RM produced amphiphilic materials with excellent interaction with the water-oil interface. Soybean oil or decalin mixtures with water (completely immiscible) were easily emulsified in the presence of the amphiphilic composites. When the composites were added to stable biodiesel-water emulsions, the amphiphilic particles diffused to the interface oil-water. These composite particles were attracted by a magnet, carrying the oil droplets with them and leading to the complete demulsification and separation of the biodiesel from the water.

  2. Simple fabrication of flexible electrodes with high metal-oxide content: electrospun reduced tungsten oxide/carbon nanofibers for lithium ion battery applications

    Science.gov (United States)

    Lee, Jaehyuk; Jo, Changshin; Park, Bangrock; Hwang, Woonbong; Lee, Hyung Ik; Yoon, Songhun; Lee, Jinwoo

    2014-08-01

    A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure.A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01033g

  3. Tuning the functionality of a carbon nanofiber-Pt-RuO2 system from charge storage to electrocatalysis.

    Science.gov (United States)

    Balan, Beena K; Kurungot, Sreekumar

    2012-09-17

    Chemical-functionalization-induced switching in the property of a hybrid system composed of a hollow carbon nanofiber (CNF) and Pt and RuO(2) nanoparticles from charge storage to electrocatalysis is presented. The results of this study show how important it is to have a clear understanding of the nature of surface functionalities in the processes involving dispersion of more than one component on various substrates including carbon nanomorphologies. When pristine CNF is used to decorate Pt and RuO(2) nanoparticles, random dispersion occurs on the CNF surface (C-PtRuO(2)). This results in mainly phase-separated nanoparticles rich in RuO(2) characteristics. In contrast to this, upon moving from the pristine CNF to those activated by a simple H(2)O(2) treatment to create oxygen-containing surface functional groups, a material rich in Pt features on the surface is obtained (F-PtRuO(2)). This is achieved because of the preferential adsorption of RuO(2) by the functionalized surface of CNF. A better affinity of the oxygen-containing functional groups on CNF toward RuO(2) mobilizes relatively faster adsorption of this moiety, leading to a well-controlled segregation of Pt nanoparticles toward the surface. Further reorganization of Pt nanoparticles leads to the formation of a Pt nanosheet structure on the surface. The electrochemical properties of these materials are initially evaluated using cyclic voltammetric analysis. The cyclic voltammetric results indicate that C-PtRuO(2) shows a charge storage property, a typical characteristic of hydrous RuO(2), whereas F-PtRuO(2) shows an oxygen reduction property, which is the characteristic feature of Pt. This clear switch in the behavior from charge storage to electrocatalysis is further confirmed by galvanostatic charge-discharge and rotating-disk-electrode studies. PMID:22946658

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

    International Nuclear Information System (INIS)

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

  5. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Carbon Nanofiller Blends

    Science.gov (United States)

    Ghose, S.; Watson, K. A.; Working, D. C.; Connell, J. W.; Smith, J. G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax 260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash ) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  6. Electrospinning of ceramic nanofibers

    Science.gov (United States)

    Eick, Benjamin M.

    Silicon Carbide (SiC) nanofibers of diameters as low as 20 nm are fabricated. The fibers were produced through the electrostatic spinning of the preceramic poly(carbomethylsilane) with pyrolysis to ceramic. A new technique was used where the preceramic was blended with polystyrene (PS) and, subsequent to electrospinning, was exposed to UV to crosslink the PS and prevent fibers flowing during pyrolysis. Electrospun SiC fibers were characterized by FTIR, TGA-DTA, SEM, TEM, XRD, and SAED. Fibers were shown to be polycrystalline and nanograined with alpha-SiC 15R polytype being dominant, where commercial fiber production methods form beta-SiC 3C. Pyrolysis of the bulk polymer blend to SiC produced alpha-SiC 15R as the dominant polytype with larger grains showing that electrospinning nanofibers affects resultant crystallinity. Fibers produced were shown to have a core-shell structure of an oxide scale that was variable by pyrolysis conditions. Metal oxide powders (chromium oxide, cobalt oxide, iron oxide, silicon oxide, tantalum oxide, titanium oxide, tungsten oxide, vanadium oxide, and zirconium oxide), were converted to metal carbide powders and metal nitride powders by the process of carbothermal reduction (CTR). Synthetic pitch was explored as an alternative to graphite which is a common carbon source for CTR. It was shown via characterization with XRD that pitch performs as well and in some cases better than graphite and is therefore a viable alternative in CTR. Conversion of metal oxide powders with pitch led to conversion of sol-gel based metal oxide nanofibers produced by electrospinning. Pitch was soluble in the solutions xv that were electrospun allowing for intimate contact between the sol-gel and the carbon source for CTR. This method became a two step processing method to produce metal carbide and nitride nanofibers: first electrospin sol-gel based metal oxide nanofibers and subsequently pyrolize them in the manner of CTR to transform them. Results indicate that this method was capable of transforming hafnium, niobium, tantalum, titanium, vanadium, and zirconium sol-gel nanofibers to metal carbides and nitrides.

  7. The effect of catalysts and underlayer metals on the properties of PECVD-grown carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sun Xuhui; Gao Jing [Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123 (China); Li Ke; Wu, Raymond; Wilhite, Patrick; Saito, Tsutomu; Yang, Cary Y, E-mail: xhsun@suda.edu.cn [Center for Nanostructures, Santa Clara University, Santa Clara, CA 95053 (United States)

    2010-01-29

    The growth behaviors and contact resistances of vertically aligned carbon nanotubes (CNTs) and carbon nanofibers (CNFs) grown on different underlayer metals are investigated. The average diameter, diameter distribution, density, growth rate and contact resistance exhibit strong correlation with the choice of catalyst/underlayer combination. These observations are analyzed in terms of interactions between the catalyst and the underlayer metal. The CNT via test structure has been designed and fabricated to make current-voltage measurements on single CNTs using a nanomanipulator under scanning electron microscopy (SEM) imaging. By analyzing the dependence of measured resistance on CNT diameter, the CNT-metal contact resistance can be extracted. The contact resistances between as-grown CNTs and different underlayer metals are determined. Relationships between contact resistances and various combinations of catalysts and underlayer metals are investigated.

  8. Hydrogenation of p-chloronitrobenzene over nanostructured-carbon-supported ruthenium catalysts.

    Science.gov (United States)

    Oubenali, Mustapha; Vanucci, Giuditta; Machado, Bruno; Kacimi, Mohammed; Ziyad, Mahfoud; Faria, Joaquim; Raspolli-Galetti, Anna; Serp, Philippe

    2011-07-18

    Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been used for the first time to support ruthenium nanoparticles for the hydrogenation of p-chloronitrobenzene (p-CNB) to produce selectively p-chloroaniline. The preparation of well-dispersed ruthenium catalysts from the [Ru(3)(CO)(12)] precursor required activation of the purified supports by nitric acid oxidation. The supports, purified and functionalized, and the supported catalysts have been characterized by a range of techniques. The catalytic activity of these materials for the hydrogenation of p-CNB at 35 bar and 60?°C is shown to reach as high as 18 mol(p-CNB)g(Ru)(-1)?h(-1), which is one order of magnitude higher than a commercial Ru/Al(2)O(3) catalyst. Selectivities between 92 and 94?% are systematically obtained, the major byproduct being aniline. PMID:21656695

  9. Large Scale Synthesis of Carbon Nanofibres on Sodium Chloride Support

    OpenAIRE

    Ravindra Rajarao; Badekai Ramachandra Bhat

    2012-01-01

    Large scale synthesis of carbon nanofibres (CNFs) on a sodium chloride support has been achieved. CNFs have been synthesized using metal oxalate (Ni, Co and Fe) as catalyst precursors at 680 ?C by chemical vapour deposition method. Upon pyrolysis, this catalyst precursors yield catalyst nanoparticles directly. The sodium chloride was used as a catalyst support, it was chosen because of its non?toxic and water soluble nature. Problems, such as the detrimental effect of CNFs, the detrimenta...

  10. 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

    High Q resonators are a critical component of stable, low-noise communication systems, radar, and precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits, resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW and SAW resonators compared to their electronic counterparts. The other advantages of mechanical resonators are their inherently higher radiation tolerance, a factor that makes them attractive for NASA s extreme environment planetary missions, for example to the Jovian environments where the radiation doses are at hostile levels. Despite these advantages, both BAW and SAW resonators suffer from low resonant frequencies and they are also physically large, which precludes their integration into miniaturized electronic systems. Because there is a need to move the resonant frequency of oscillators to the order of gigahertz, new technologies and materials are being investigated that will make performance at those frequencies attainable. By moving to nanoscale structures, in this case vertically oriented, cantilevered carbon nanotubes (CNTs), that have larger aspect ratios (length/thickness) and extremely high elastic moduli, it is possible to overcome the two disadvantages of both bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Nano-electro-mechanical systems (NEMS) that utilize high aspect ratio nanomaterials exhibiting high elastic moduli (e.g., carbon-based nanomaterials) benefit from high Qs, operate at high frequency, and have small force constants that translate to high responsivity that results in improved sensitivity, lower power consumption, and im - proved tunablity. NEMS resonators have recently been demonstrated using topdown, 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.

  11. Polymethylsilsesquioxane-cellulose nanofiber biocomposite aerogels with high thermal insulation, bendability, and superhydrophobicity.

    Science.gov (United States)

    Hayase, Gen; Kanamori, Kazuyoshi; Abe, Kentaro; Yano, Hiroyuki; Maeno, Ayaka; Kaji, Hironori; Nakanishi, Kazuki

    2014-06-25

    Polymethylsilsesquioxane-cellulose nanofiber (PMSQ-CNF) composite aerogels have been prepared through sol-gel in a solvent containing a small amount of CNFs as suspension. Since these composite aerogels do not show excessive aggregation of PMSQ and CNF, the original PMSQ networks are not disturbed. Composite aerogels with low density (0.020 g cm(-3) at lowest), low thermal conductivity (15 mW m(-1) K(-1)), visible light translucency, bending flexibility, and superhydrophobicity thus have been successfully obtained. In particular, the lowest density and bending flexibility have been achieved with the aid of the physical supporting effect of CNFs, and the lowest thermal conductivity is comparable with the original PMSQ aerogels and standard silica aerogels. The PMSQ-CNF composite aerogels would be a candidate to practical high-performance thermal insulating materials. PMID:24865571

  12. Synergetic role of nanoparticles and micro-scale short carbon fibers on the mechanical profiles of epoxy resin

    Directory of Open Access Journals (Sweden)

    2011-10-01

    Full Text Available It was demonstrated in our previous work that the combined carbon nanofibers (CNFs and microsized short carbon fibers (SCFs in epoxy (EP leads to significant improvements in the mechanical properties of the matrix. In this work, the effect of nano-SiO2 particles, having an extremely different aspect ratio from CNFs, on the tensile property and fracture toughness of SCFs-filled EP was studied. It was revealed that the combined use of SCFs and silica nanoparticles exerts a synergetic effect on the mechanical and fracture properties of EP. Application of SCFs and the nanoparticles is an effective way to greatly enhance the modulus, strength and fracture toughness of the EP simultaneously. The synergetic role of the multiscale fillers was explained by prominent changes in the stress state near the microsized fillers and the plastic zone ahead of the crack tip. The synergetic role of multiscale fillers is expected to open up new opportunities to formulate highperformance EP composites.

  13. Synthesis of carbon nano fiber using carbon black as precursor

    International Nuclear Information System (INIS)

    This paper record our attempt to convert carbon black to carbon nanofiber. The carbon nanofiber was synthesized by mixing carbon black with catalyst solution of FeMo. The mixture was heated under N2 flow at 1000 degree C for 5 minutes. The resultants carbon powder is characterised using scanning electron microscope (SEM). Only a very very small amount of carbon nanofiber is produced with major products of graphitic and amorphous carbon. Carbon nanofiber was found like patches of grass on amorphous carbon. The catalyst was solidified into clusters. The carbon nanofiber observed is believed to grow on Fe catalyst cluster on Mo-carbide surface. (Authors)

  14. Decomposição catalítica da hidrazina sobre irídio suportado em compósitos à base de nanofibras de carbono para propulsão espacial: testes em condições reais Catalytic decomposition of hydrazine over iridium supported on carbon nanofiber composites for propulsion in space: tests under real-life conditions

    Directory of Open Access Journals (Sweden)

    Ricardo Vieira

    2005-02-01

    Full Text Available The aim of this work is to present the catalytic performance of iridium supported on carbon nanofibers with macroscopic shaping in a 2 N hydrazine microthruster placed inside a vacuum chamber in order to reproduce real-life conditions. The performances obtained are compared to those of the commercial catalyst Shell 405. The carbon-nanofiber based catalyst showed better performance than the commercial catalyst from the standpoint of activity due to its texture and its thermal conductivity.

  15. Decomposição catalítica da hidrazina sobre irídio suportado em compósitos à base de nanofibras de carbono para propulsão espacial: testes em condições reais Catalytic decomposition of hydrazine over iridium supported on carbon nanofiber composites for propulsion in space: tests under real-life conditions

    OpenAIRE

    Ricardo Vieira; Demétrio Bastos Netto; Pierre Bernhardt; Marc-Jacques Ledoux; Cuong Pham-Huu

    2005-01-01

    The aim of this work is to present the catalytic performance of iridium supported on carbon nanofibers with macroscopic shaping in a 2 N hydrazine microthruster placed inside a vacuum chamber in order to reproduce real-life conditions. The performances obtained are compared to those of the commercial catalyst Shell 405. The carbon-nanofiber based catalyst showed better performance than the commercial catalyst from the standpoint of activity due to its texture and its thermal conductivity.

  16. A self-assembled superhydrophobic electrospun carbon-silica nanofiber sponge for selective removal and recovery of oils and organic solvents.

    Science.gov (United States)

    Tai, Ming Hang; Tan, Benny Yong Liang; Juay, Jermyn; Sun, Darren D; Leckie, James O

    2015-03-27

    An oil spill needs timely cleanup before it spreads and poses serious environmental threat to the polluted area. This always requires the cleanup techniques to be efficient and cost-effective. In this work, a lightweight and compressible sponge made of carbon-silica nanofibers is derived from electrospinning nanotechnology that is low-cost, versatile, and readily scalable. The fabricated sponge has high porosity (>99?%) and displays ultra-hydrophobicity and superoleophilicity, thus making it a suitable material as an oil adsorbent. Owing to its high porosity and low density, the sponge is capable of adsorbing oil up to 140?times its own weight with its sorption rate showing solution viscosity dependence. Furthermore, sponge regeneration and oil recovery are feasible by using either cyclic distillation or mechanical squeezing. PMID:25597480

  17. Improving the microstructure and electrochemical performance of carbon nanofibers containing graphene-wrapped silicon nanoparticles as a Li-ion battery anode

    Science.gov (United States)

    Kim, So Yeun; Yang, Kap Seung; Kim, Bo-Hye

    2015-01-01

    A novel anode material for lithium-ion batteries, graphene-wrapped Si nanoparticles (NPs) embedded in carbon composite nanofibers (CCNFs) with G/Si, is fabricated by electrospinning and subsequent thermal treatment. In CCNFs with G/Si, Si NPs are distributed and preserved inside the CNF surface because the graphene wrapping the Si NPs help prevent agglomeration and ensure a good dispersion of Si NPs inside the CNF matrix. 20-GSP prepared from a weight ratio of 20 wt% of G/Si to polyacrylonitrile exhibits stable capacity retention and a reversible capacity of above 600 mAh g-1 up to 100 cycles. The high cycling performance and superior reversible capacity of the 20-GSP anode can be attributed to the one-dimensional nanofibrous structure with non-agglomerated Si NPs in the CNF matrix, which promotes charge transfer, maintains a stable electrical contact, and buffers the Si volume expansion.

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

    International Nuclear Information System (INIS)

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

  19. Preparation, characterization and electrochemical properties of a graphene-like carbon nano-fragment material

    International Nuclear Information System (INIS)

    Highlights: • The spent graphite material is utilized to prepare carbon nano-fragments (CNFs). • The preparation procedure is based on chemical oxidation and ultrasonic crushing. • The as-prepared graphene-like CNFs are systemically characterized. • The CNFs exhibit high electrocatalytic and electrochemical energy-storage properties. - Abstract: A graphene-like nanomaterial, carbon nano-fragments (CNFs), is obtained using the graphite anodes of spent lithium-ion batteries (LIBs) as carbon source, and its morphology, structure, functional groups, and reactivity are characterized to evaluate the properties and potential applications. The interlayer space increase, layer distortion, and remnant lithium of the waste lithium-intercalated graphite are utilized to prepare the oxidized CNFs (ox-CNFs) through a chemical oxidation and ultrasonic crushing process. These ox-CNFs exhibit a size distribution of 15 nm to 2 ?m and excellent hydrophilicity, and disperse well in an aqueous suspension. Under the hydrothermal condition at 180 °C for 12 h, the ox-CNFs are converted into a suspension of reduced CNFs (re-CNFs), or a cylindrical aggregate when the concentration exceeds 2 mg·mL?1. The spectroscopic results demonstrate that there are abundant edges, defects, and functional groups existing on the CNFs, which affect their reactive, electronic, and electrochemical properties. Thereinto, the vacuum-dried ox-CNFs film can be converted from an insulator to a conductor after a chemical reduction by hydroiodic acid. And the re-CNFs modified glass carbon electrode (re-CNFs/GCE) exhibits enhanced electrocatalytic activity of about 8 times than the GCE to the oxidation reaction of dopamine. Furthermore, with the addition of the carboxylic ox-CNFs in aniline, the CNFs/polyaniline composite discharges a capacitance of 356.4 F·g?1 at 2 mV·s?1, an increase of 80.5% compared to the polyaniline. This preparation entails not only novel carbon nanomaterials but also an excellent disposal method of spent graphite, showing special significance in materials innovation and environmental science

  20. Novos materiais à base de nanofibras de carbono como suporte de catalisador na decomposição da hidrazina Carbon nanofibers a new catalyst support for hydrazine decomposition

    Directory of Open Access Journals (Sweden)

    Ricardo Vieira

    2003-10-01

    Full Text Available Today satellites propulsion is based on the use of monopropellant and/or bipropellant chemical systems. The maneuvering of satellite is based on the hydrazine decomposition micropropulsors catalyzed by metallic iridium supported on g-alumina. This reaction is a surface reaction and is strongly exothermic and implies that the operation of the micropropulsor is controlled by the mass and heat diffusions. For this reason and for the fact that the propulsor operation is frequently in pulsed regime, the catalyst should support high pressure and temperature variations within a short time period. The performance and the durability of the commercial catalyst are jeopardized by the low thermal conductivity of the alumina. The low thermal conductivity of the alumina support restricts the heat diffusion and leads to the formation of hot spots on the catalyst surface causing the metal sintering and/or fractures of the support, resulting in loss of the activity and catalyst destruction. This work presents the synthesis and characterization of new carbon composite support for the active element iridium, in substitution of the commercial catalysts alumina based support. These supports are constituted of carbon nanofibers (30 to 40 nm diameter supported on a macroscopic carbon felt. These materials present high thermal conductivity and mechanical resistance, as well as the easiness to be shaped with different macroscopic shapes. The mechanical stability and the performance of the iridium supported on the carbon composite support, evaluated in a laboratory scale test in hydrazine decomposition reaction, are superior compared to the commercial catalyst.

  1. Preparation and electrochemical performance of hyper-networked Li{sub 4}Ti{sub 5}O{sub 12}/carbon hybrid nanofiber sheets for a battery-supercapacitor hybrid system

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hong Soo; Kim, TaeHoon; Im, Ji Hyuk; Park, Chong Rae, E-mail: crpark@snu.ac.kr [Carbon Nanomaterials Design Laboratory, Global Research Laboratory, Research Institute of Advanced Materials, and Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2011-10-07

    Hyper-networked Li{sub 4}Ti{sub 5}O{sub 12}/carbon hybrid nanofiber sheets that contain both a faradaically rechargeable battery-type component, namely Li{sub 4}Ti{sub 5}O{sub 12}, and a non-faradaically rechargeable supercapacitor-type component, namely N-enriched carbon, are prepared by electrospinning and their dual function as a negative electrode of lithium-ion batteries (LIBs) and a capacitor is tested for a new class of hybrid energy storage (denoted BatCap). An aqueous solution composed of polyvinylpyrrolidone, lithium hydroxide, titanium(IV) bis(ammonium-lactato)dihydroxide and ammonium persulfate is electrospun to obtain hyper-networked nanofiber sheets. Next, the sheets are exposed to pyrrole monomer vapor to prepare the polypyrrole-coated nanofiber sheets (PPy-HNS). The hyper-networked Li{sub 4}Ti{sub 5}O{sub 12}/N-enriched carbon hybrid nanofiber sheets (LTO/C-HNS) are then obtained by a stepwise heat treatment of the PPy-HNS. The LTO/C-HNS deliver a specific capacity of 135 mAh g{sup -1} at 4000 mA g{sup -1} as a negative electrode for LIBs. In addition, potentiodynamic experiments are performed using a full cell with activated carbon (AC) as the positive electrode and LTO/C-HNS as the negative electrode to estimate the capacitance properties. This new asymmetric electrode system exhibits a high energy density of 91 W kg{sup -1} and 22 W kg{sup -1} at power densities of 50 W kg{sup -1} and 4000 W kg{sup -1}, respectively, which are superior to the values observed for the AC||AC symmetric electrode system.

  2. Electrospun nanofiber membranes for electrically activated shape memory nanocomposites

    Science.gov (United States)

    Zhang, Fenghua; Zhang, Zhichun; Liu, Yanju; Leng, Jinsong

    2014-06-01

    A novel shape memory nanocomposite system, consisting of a thermoplastic Nafion polymer and ultrathin electrospun polyacrylonitrile (PAN)-based carbonization nanofiber membranes, is successfully synthesized. PAN-based carbonization nanofiber networks that offer responses to deformations are considered to be an excellent actuation source. Significant improvement in the electrical conductivity of carbon nanofiber membranes is found by adjusting the applied voltage power in the electrospinning PAN process varying from 7.85 to 12.30 S cm-1. The porous structure of the carbon nanofiber membranes provides a large specific surface area and interfacial contact area when combined with the polymer matrix. Shape memory Nafion nanocomposites filled with interpenetrating non-woven electrospun PAN carbonization membranes can be actuated by applying 14 V electrical voltage within 5 s. The results, as demonstrated through morphology, electrical and thermal measurements and a shape recovery test, suggest a valuable route to producing soft nanocomposites.

  3. Manufacturing and Shear Response Characterization of Carbon Nanofiber Modified CFRP Using the Out-of-Autoclave-Vacuum-Bag-Only Cure Process

    Science.gov (United States)

    McDonald, Erin E.; Wallace, Landon F.; Hickman, Gregory J. S.; Hsiao, Kuang-Ting

    2014-01-01

    The interlaminar shear response is studied for carbon nanofiber (CNF) modified out-of-autoclave-vacuum-bag-only (OOA-VBO) carbon fiber reinforced plastic (CFRP). Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testingwas used to study the in-plane shear performance of [±45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC) surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination. PMID:24688435

  4. A carbon fiber-ZnS nanocomposite for dual application as an efficient cold cathode as well as a luminescent anode for display technology

    Science.gov (United States)

    Jha, Arunava; Sarkar, Sudipta Kumar; Sen, Dipayan; Chattopadhyay, K. K.

    2015-01-01

    In the current work we present a simple technique to develop a carbon nanofiber (CNF)/zinc sulfide (ZnS) composite material for excellent FED application. CNFs and ZnS microspheres were synthesized by following a simple thermal chemical vapor deposition and hydrothermal procedure, respectively. A rigorous chemical mixture of CNF and ZnS was prepared to produce the CNF-ZnS composite material. The cathodo-luminescence intensity of the composite improved immensely compared to pure ZnS, also the composite material showed better field emission than pure CNFs. For pure CNF the turn-on field was found to be 2.1 V ?m-1 whereas for the CNF-ZnS composite it reduced to a value of 1.72 V ?m-1. Altogether the composite happened to be an ideal element for both the anode and cathode of a FED system. Furthermore, simulation of our CNF-ZnS composite system using the finite element modeling method also ensured the betterment of field emission from CNF after surface attachment of ZnS nanoclusters.

  5. A carbon fiber-ZnS nanocomposite for dual application as an efficient cold cathode as well as a luminescent anode for display technology.

    Science.gov (United States)

    Jha, Arunava; Sarkar, Sudipta Kumar; Sen, Dipayan; Chattopadhyay, K K

    2015-02-14

    In the current work we present a simple technique to develop a carbon nanofiber (CNF)/zinc sulfide (ZnS) composite material for excellent FED application. CNFs and ZnS microspheres were synthesized by following a simple thermal chemical vapor deposition and hydrothermal procedure, respectively. A rigorous chemical mixture of CNF and ZnS was prepared to produce the CNF-ZnS composite material. The cathodo-luminescence intensity of the composite improved immensely compared to pure ZnS, also the composite material showed better field emission than pure CNFs. For pure CNF the turn-on field was found to be 2.1 V ?m(-1) whereas for the CNF-ZnS composite it reduced to a value of 1.72 V ?m(-1). Altogether the composite happened to be an ideal element for both the anode and cathode of a FED system. Furthermore, simulation of our CNF-ZnS composite system using the finite element modeling method also ensured the betterment of field emission from CNF after surface attachment of ZnS nanoclusters. PMID:25572257

  6. Novos materiais à base de nanofibras de carbono como suporte de catalisador na decomposição da hidrazina / Carbon nanofibers a new catalyst support for hydrazine decomposition

    Scientific Electronic Library Online (English)

    Ricardo, Vieira; Cuong, Pham-Huu; Nicolas, Keller; Marc J., Ledoux.

    2003-10-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english Today satellites propulsion is based on the use of monopropellant and/or bipropellant chemical systems. The maneuvering of satellite is based on the hydrazine decomposition micropropulsors catalyzed by metallic iridium supported on g-alumina. This reaction is a surface reaction and is strongly exoth [...] ermic and implies that the operation of the micropropulsor is controlled by the mass and heat diffusions. For this reason and for the fact that the propulsor operation is frequently in pulsed regime, the catalyst should support high pressure and temperature variations within a short time period. The performance and the durability of the commercial catalyst are jeopardized by the low thermal conductivity of the alumina. The low thermal conductivity of the alumina support restricts the heat diffusion and leads to the formation of hot spots on the catalyst surface causing the metal sintering and/or fractures of the support, resulting in loss of the activity and catalyst destruction. This work presents the synthesis and characterization of new carbon composite support for the active element iridium, in substitution of the commercial catalysts alumina based support. These supports are constituted of carbon nanofibers (30 to 40 nm diameter) supported on a macroscopic carbon felt. These materials present high thermal conductivity and mechanical resistance, as well as the easiness to be shaped with different macroscopic shapes. The mechanical stability and the performance of the iridium supported on the carbon composite support, evaluated in a laboratory scale test in hydrazine decomposition reaction, are superior compared to the commercial catalyst.

  7. Protease Sensitive Fluorescent Nanofibers

    OpenAIRE

    Law, Benedict; Weissleder, Ralph; Tung, Ching-hsuan

    2007-01-01

    We report the design and synthesis of enzyme responsive nanofibers. The fibers are composed of self-assembled hydrophobic ?-sheet peptides incorporating protease sensitive domains, fluorescent reporters and hydrophilic polyethyleneglycol (PEG) units. Using urokinase plasminogen activator (uPA) as a model system, nanofibers were developed to release fluorescent fragments upon uPA incubation. These protease sensitive nanofibers may have considerable biomedical applications as diagnostic sensor...

  8. Anomalous capacity increase at high-rates in lithium-ion battery anodes based on silicon-coated vertically aligned carbon nanofibers

    Science.gov (United States)

    Klankowski, Steven A.; Pandey, Gaind P.; Cruden, Brett A.; Liu, Jianwei; Wu, Judy; Rojeski, Ronald A.; Li, Jun

    2015-02-01

    This study reports of a multi-scale hierarchical lithium-ion battery (LIB) anode that shows a surprising increase in storage capacity at higher current rates from ?3C to ?8C. The anode, composed of forest-like vertically aligned carbon nanofibers coaxially coated with Si shells, is shown to obtain a storage capacity of 3000-3500 mAh (gSi)-1 and greater than 99% coulombic efficiency at a 1C (or C/1) rate, leading to remarkable stability over 500 charge-discharge cycles. In contrast to other studies, this hierarchical LIB anode shows superior high-rate capability where the capacity decreased by less than 7% from ?C/8 to ?3C rates and, more importantly, increased by a few percent from ?3C to ?8C rates, displaying a new phenomenon that becomes more evident after going through long cycles. Electron microscopy, Raman, and electrochemical impedance spectroscopy reveal that the electrode structure remains stable during long cycling and that this enhanced property is likely associated with the combination of the unique nanocolumnar microstructure of the Si coating and the vertical core-shell architecture. It reveals an exciting potential to develop high-performance lithium-ion batteries.

  9. A template-free method for preparation of cobalt nanoparticles embedded in N-doped carbon nanofibers with a hierarchical pore structure for oxygen reduction.

    Science.gov (United States)

    Wang, Shuguang; Cui, Zhentao; Cao, Minhua

    2015-01-26

    Designing and preparing porous materials without using any templates is a challenge. Herein, single-nozzle electrospinning technology coupled with post pyrolysis is applied to prepare cobalt nanoparticles embedded in N-doped carbon nanofibers with a hierarchical pore structure (HP-Co-NCNFs). The resultant HP-Co-NCNFs have lengths up to several millimeters with an average diameter of 200?nm and possess abundant micro/meso/macropores on both the surface and within the fibers. Such a microstructure endows the surface area as high as 115?m(2) ?g(-1) . When used as an electrocatalyst for the oxygen reduction reaction (ORR), the HP-Co-NCNFs exhibit outstanding electrochemical performance in terms of activity, methanol tolerance, and durability. The hierarchically porous structure and high surface area can effectively decrease the mass transport resistance and increase the exposed ORR active sites. The sufficient amount of exposed ORR active sites along with accessible transport channel and enhanced electrical conductivity may be responsible for the good electrocatalytic performance. PMID:25449793

  10. Achieving highly dispersed nanofibres at high loading in carbon nanofibre-metal composites

    International Nuclear Information System (INIS)

    In order to tap into the advantages of the properties of carbon nanotubes (CNTs) or carbon nanofibres (CNFs) in composites, the high dispersion of CNTs (or CNFs) and strong interfacial bonding are the key issues which are still challenging. In the current work, a novel approach, consisting of in situ synthesis of CNFs within the Cu powders and mixing Cu ions with the in situ CNF(Ni/Y)-Cu composite powders in a solvent, was developed to highly disperse CNFs in a Cu matrix. The composite, produced by vacuum hot pressing, shows extremely high strength, 3.6 times more than that of the matrix material alone. It is worth mentioning that this method can disperse CNFs at high loading in a metal matrix, inferring good potential for applications, such as electronic packaging materials.

  11. Achieving highly dispersed nanofibres at high loading in carbon nanofibre-metal composites

    Science.gov (United States)

    Kang, Jianli; Nash, Philip; Li, Jiajun; Shi, Chunsheng; Zhao, Naiqin

    2009-06-01

    In order to tap into the advantages of the properties of carbon nanotubes (CNTs) or carbon nanofibres (CNFs) in composites, the high dispersion of CNTs (or CNFs) and strong interfacial bonding are the key issues which are still challenging. In the current work, a novel approach, consisting of in situ synthesis of CNFs within the Cu powders and mixing Cu ions with the in situ CNF(Ni/Y)-Cu composite powders in a solvent, was developed to highly disperse CNFs in a Cu matrix. The composite, produced by vacuum hot pressing, shows extremely high strength, 3.6 times more than that of the matrix material alone. It is worth mentioning that this method can disperse CNFs at high loading in a metal matrix, inferring good potential for applications, such as electronic packaging materials.

  12. Curvature, Hybridization and Contamination of Carbon Nanostructures Analysis Using Electron Microscopy and XANES Spectroscopy

    Directory of Open Access Journals (Sweden)

    Rolant Eba Medjo

    2014-02-01

    Full Text Available The ability to control the nanoscale shape of carbon nanostructures during wide-scale synthesis process is an essential goal in research for Nanotechnology applications. This paper reports a significant progress toward that goal. Variant CVD has been used for the synthesis of the samples studied. Curvature, hybridization and contamination are analyzed using Electron Microscopies and XANES spectroscopy. The investigations of the results show that four types of samples are obtained. They are carbon nanotubes (CNTs, carbon nanofibers (CNFs, carbon nanowalls (CNWs and carbon nanoparticles (CNPs. Almost all of them have catalyst nanoparticles (metal on top in top growth model or on base in base growth model and encapsulated or adsorbed in sidewalls. The orientation of tubular carbon nanomaterials depends on operating parameters. They are classified in three groups: the poorly oriented, the medium oriented and the highly oriented. Their contamination (radicals, atoms and molecules and hybridization are intrinsically related to the curvature of their graphene layers. XANES spectroscopy allows quantitative characterization of nanomaterials.

  13. Study of the fire resistant behavior of unfilled and carbon nanofibers reinforced polybenzimidazole coating for structural applications:

    OpenAIRE

    Iqbal, H. M. S.; Stec, A. A.; Patel, P.; Bhowmik, S.; Benedictus, R.

    2013-01-01

    With increasing interest in epoxy-based carbon fiber composites for structural applications, it is important to improve the fire resistant properties of these materials. The fire resistant performance of these materials can be improved either by using high performance epoxy resin for manufacturing carbon fiber composite or by protecting the previously used epoxy-based composite with some fire resistant coating. In this context, work is carried out to evaluate the fire resistance performance o...

  14. Rippling of polymer nanofibers

    Science.gov (United States)

    Wu, Xiang-Fa; Kostogorova-Beller, Yulia Y.; Goponenko, Alexander V.; Hou, Haoqing; Dzenis, Yuris A.

    2008-12-01

    This paper studies the evolution mechanism of surface rippling in polymer nanofibers under axial stretching. This rippling phenomenon has been detected in as-electrospun polyacrylonitrile in recent single-fiber tension tests, and in electrospun polyimide nanofibers after imidization. We herein propose a one-dimensional nonlinear elastic model that takes into account the combined effect of surface tension and nonlinear elasticity during the rippling initiation and its evolution in compliant polymer nanofibers. The polymer nanofiber is modeled as an incompressible, isotropically hyperelastic Mooney-Rivlin solid. The fiber geometry prior to rippling is considered as a long circular cylinder. The governing equation of surface rippling is established through linear perturbation of the static equilibrium state of the nanofiber subjected to finite axial prestretching. The critical stretch and ripple wavelength are determined in terms of surface tension, elastic property, and fiber radius. Numerical examples are demonstrated to examine these dependencies. In addition, a critical fiber radius is determined, below which the polymer nanofibers are intrinsically unstable. The present model, therefore, is capable of predicting the rippling condition in compliant nanofibers, and can be further used as a continuum mechanics approach for the study of surface instability and nonlinear wave propagation in compliant fibers and wires at the nanoscale.

  15. Rippling of polymer nanofibers.

    Science.gov (United States)

    Wu, Xiang-Fa; Kostogorova-Beller, Yulia Y; Goponenko, Alexander V; Hou, Haoqing; Dzenis, Yuris A

    2008-12-01

    This paper studies the evolution mechanism of surface rippling in polymer nanofibers under axial stretching. This rippling phenomenon has been detected in as-electrospun polyacrylonitrile in recent single-fiber tension tests, and in electrospun polyimide nanofibers after imidization. We herein propose a one-dimensional nonlinear elastic model that takes into account the combined effect of surface tension and nonlinear elasticity during the rippling initiation and its evolution in compliant polymer nanofibers. The polymer nanofiber is modeled as an incompressible, isotropically hyperelastic Mooney-Rivlin solid. The fiber geometry prior to rippling is considered as a long circular cylinder. The governing equation of surface rippling is established through linear perturbation of the static equilibrium state of the nanofiber subjected to finite axial prestretching. The critical stretch and ripple wavelength are determined in terms of surface tension, elastic property, and fiber radius. Numerical examples are demonstrated to examine these dependencies. In addition, a critical fiber radius is determined, below which the polymer nanofibers are intrinsically unstable. The present model, therefore, is capable of predicting the rippling condition in compliant nanofibers, and can be further used as a continuum mechanics approach for the study of surface instability and nonlinear wave propagation in compliant fibers and wires at the nanoscale. PMID:19256861

  16. Electrospun Gallium Nitride Nanofibers

    International Nuclear Information System (INIS)

    The high thermal conductivity and wide bandgap of gallium nitride (GaN) are desirable characteristics in optoelectronics and sensing applications. In comparison to thin films and powders, in the nanofiber morphology the sensitivity of GaN is expected to increase as the exposed area (proportional to the length) increases. In this work we present electrospinning as a novel technique in the fabrication of GaN nanofibers. Electrospinning, invented in the 1930s, is a simple, inexpensive, and rapid technique to produce microscopically long ultrafine fibers. GaN nanofibers are produced using gallium nitrate and dimethyl-acetamide as precursors. After electrospinning, thermal decomposition under an inert atmosphere is used to pyrolyze the polymer. To complete the preparation, the nanofibers are sintered in a tube furnace under a NH3 flow. Both scanning electron microscopy and profilometry show that the process produces continuous and uniform fibers with diameters ranging from 20 to a few hundred nanometers, and lengths of up to a few centimeters. X-ray diffraction (XRD) analysis shows the development of GaN nanofibers with hexagonal wurtzite structure. Future work includes additional characterization using transmission electron microscopy and XRD to understand the role of precursors and nitridation in nanofiber synthesis, and the use of single nanofibers for the construction of optical and gas sensing devices.

  17. High-performance hybrid (electrostatic double-layer and faradaic capacitor-based) polymer actuators incorporating nickel oxide and vapor-grown carbon nanofibers.

    Science.gov (United States)

    Terasawa, Naohiro; Asaka, Kinji

    2014-12-01

    The electrochemical and electromechanical properties of polymeric actuators prepared using nickel peroxide hydrate (NiO2·xH2O) or nickel peroxide anhydride (NiO2)/vapor-grown carbon nanofibers (VGCF)/ionic liquid (IL) electrodes were compared with actuators prepared using solely VGCFs or single-walled carbon nanotubes (SWCNTs) and an IL. The electrode in these actuator systems is equivalent to an electrochemical capacitor (EC) exhibiting both electrostatic double-layer capacitor (EDLC)- and faradaic capacitor (FC)-like behaviors. The capacitance of the metal oxide (NiO2·xH2O or NiO2)/VGCF/IL electrode is primarily attributable to the EDLC mechanism such that, at low frequencies, the strains exhibited by the NiO2·xH2O/VGCF/IL and NiO2/VGCF/IL actuators primarily result from the FC mechanism. The VGCFs in the NiO2·xH2O/VGCF/IL and NiO2/VGCF/IL actuators strengthen the EDLC mechanism and increase the electroconductivity of the devices. The mechanism underlying the functioning of the NiO2·xH2O/VGCF/IL actuator in which NiO2·xH2O/VGCF = 1.0 was found to be different from that of the devices produced using solely VGCFs or SWCNTs, which exhibited only the EDLC mechanism. In addition, it was found that both NiO2 and VGCFs are essential with regard to producing actuators that are capable of exhibiting strain levels greater than those of SWCNT-based polymer actuators and are thus suitable for practical applications. Furthermore, the frequency dependence of the displacement responses of the NiO2·xH2O/VGCF and NiO2/VGCF polymer actuators were successfully simulated using a double-layer charging kinetic model. This model, which accounted for the oxidization and reduction reactions of the metal oxide, can also be applied to SWCNT-based actuators. The results of electromechanical response simulations for the NiO2·xH2O/VGCF and NiO2/VGCF actuators predicted the strains at low frequencies as well as the time constants of the devices, confirming that the model is applicable not only to EDLC-based actuator systems but also to the fabricated EDLC/FC system. PMID:25354668

  18. Fabrication of electrospun nanofibers bundles

    Science.gov (United States)

    Ye, Junjun; Sun, Daoheng

    2007-12-01

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

  19. Superhydrophobic terpolymer nanofibers containing perfluoroethyl alkyl methacrylate by electrospinning

    International Nuclear Information System (INIS)

    A new statistical terpolymer containing perfluoroethyl alkyl methacrylate (Zonyl-TM), methyl methacrylate and butyl acrylate, poly(Zonyl-TM-ran-MMA-ran-BA) was synthesized in supercritical carbon dioxide at 200 bar and 80 °C using AIBN as an initiator by heterogeneous free radical copolymerization. Nanofibers of this terpolymer were produced by electrospinning from its DMF solution. The structural and thermal properties of terpolymers and electrospun poly(Zonyl-TM-MMA-BA) nanofibers were analyzed using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and differential scanning calorimetry. Nanofiber morphology was investigated by scanning electron microscopy. Electrospun nanofiber layer was found to be superhydrophobic with a water contact angle of 172 ± 1° and highly oleophobic with hexadecane, glycerol and ethylene glycol contact angles of 70 ± 1°, 167 ± 1° and 163 ± 1° respectively. The change of the contact angle results on the electrospun fiber layer and flat terpolymer surfaces by varying feed monomer composition were compared and discussed in the text.

  20. Capillography of Mats of Nanofibers

    Science.gov (United States)

    Noca, Flavio; Sansom, Elijah; Zhou, Jijie; Gharib, Mory

    2008-01-01

    Capillography (from the Latin capillus, 'hair', and the Greek graphein, to write ) is a recently conceived technique for forming mats of nanofibers into useful patterns. The concept was inspired by experiments on carpetlike mats of multiwalled carbon nanotubes. Capillography may have the potential to be a less-expensive, less-time-consuming alternative to electron-beam lithography as a means of nanoscale patterning for the fabrication of small devices and instruments. In capillography, one exploits the lateral capillary forces exerted on small objects that pierce the surface of a liquid. If the small objects are identical, then the forces are always attractive. Two examples of the effects of such forces are the agglomeration of small particles floating on the surface of a pond and the drawing together of hairs of a wet paintbrush upon removal of the brush from water. Because nanoscale objects brought into contact remain stuck together indefinitely due to Van der Waals forces, patterns formed by capillography remain even upon removal of the liquid. For the experiments on the mats of carbon nanotubes, a surfactant solution capable of wetting carbon nanotubes (which are ultra-hydrophobic) was prepared. The mats were wetted with the solution, then dried. Once the mats were dry, it was found that the nanotubes had become ordered into various patterns, including nestlike indentations, trenches, and various combinations thereof. It may be possible to exploit such ordering effects through controlled wetting and drying of designated portions of mats of carbon nanotubes (and, perhaps, mats of nanofibers of other materials) to obtain patterns similar to those heretofore formed by use of electron-beam lithography. For making patterns that include nestlike indentations, it has been conjectured that it could be possible to control the nesting processes by use of electrostatic fields. Further research is needed to understand the physics of the patterning processes in order to develop capabilities to control patterns formed in capillography.

  1. The preparation of mesoporous SnO2 nanotubes by carbon nanofibers template and their lithium storage properties

    International Nuclear Information System (INIS)

    Mesoporous SnO2 nanotubes are prepared by templating against carbon fibers through a facile solution approach followed by calcination at 800 °C for 2 h. The nanotubes are characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and nitrogen adsorption. The electrochemical performances as the anodes of lithium-ions batteries are studied by the cyclic voltammogram (CV) and galvanostatic discharge–charge voltage tests. Because of its unique structure (the mesoporous wall, internal void and open ends), the as-obtained mesoporous SnO2 nanotubes demonstrate a reversible capacity of 585 mA h g?1 up to 50 cycles at a high current density of 400 mA g?1

  2. Controlling the drug release rate from electrospun phospholipid polymer nanofibers with micro-patterned diamond-like carbon (DLC) coating

    Science.gov (United States)

    Yoshida, Soki; Hasebe, Terumitsu; Suzuki, Tetsuya; Hotta, Atsushi

    2013-03-01

    An effective way of controlling drug release from polymer fibers coated with thin diamond-like carbon (DLC) film was introduced. It is highly expected that electrospinning will produce polymer fiber and useful for drug delivery systems. The drug release rate should be rather precisely controlled in order to prevent side effects due to the burst drug-release from polymers. Our previous research has already revealed that the micro-patterned DLC could control the drug release rate from biocompatible polymer films. In this study, the drug release profile of the polymer fibers with DLC was investigated. Hydrophilic 2-methacryloyloxyethyl phosphorylcholine (MPC) was selected as a typical biocompatible polymer. It is well known that the MPC polymers show good hemocompatibility and that both MPC and DLC are excellent biocompatible materials with antithrombogenicity. The DLC/MPC composites could therefore be extensively utilized for blood-contacting medical devices. The percentile covered area with patterned DLC on MPC fibers containing drug was varied from 0% (without DLC) to 100% (fully covered). It was found that the drug eluting profiles could be effectively controlled by changing the covered area of micro-patterned DLC coatings on MPC.

  3. Structure and Mechanical Behavior of Cellulose Nanofiber and Micro-Fibrils by Molecular Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    Ken-ichi Saitoh

    2013-07-01

    Full Text Available Cellulose nanofiber (CNF and CNF micro-fibrils (CNF-MFs are computationally modeled by molecular dynamics with united atom (UA methodology of polymers. Structural stability and mechanical properties of these materials are focused on. Diffusion coefficient decreases with increase of the number of shells in CNF-MF. The structure of CNF-MFs with crystalline alignment is totally stabilized with twist which is an accumulation of torsion angles at Glycosidic bonds between monomers inside CNFs. Unique fiber drawing simulation, where a single CNF fiber is taken out of CNF-MF structure, is first conducted. The CNF fiber which is drawn out stretches up to relatively large strain, with linear increase of tensile stress. The computation results show that, the larger the number of shell structure of CNF-MF is, the larger the stretch and the stress of drawn fibers are.

  4. Bio-based polyurethane reinforced with cellulose nanofibers: A comprehensive investigation on the effect of interface.

    Science.gov (United States)

    Benhamou, Karima; Kaddami, Hamid; Magnin, Albert; Dufresne, Alain; Ahmad, Azizan

    2015-05-20

    Novel bio-based polyurethane (PU) nanocomposites composed of cellulose nanofiller extracted from the rachis of date palm tree and polycaprolactone (PCL) diol based PU were prepared by casting/evaporation. Two types of nanofiber were used: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). The mechanical and thermal properties of the nanocomposite films were studied by DMA, DSC, and tensile tests and the morphology was investigated by SEM. Bionanocomposites presented good mechanical properties in comparison to neat PU. While comparing both nanofillers, the improvement in mechanical and thermal properties was more pronounced for the nanocomposites based on CNF which could be explained, not only by the higher aspect ratio of CNF, but also by their better dispersion in the PU matrix. Calculation of the solubility parameters of the nanofiller surface polymers and of the PU segments portend a better interfacial adhesion for CNF based nanocomposites compared to CNC. PMID:25817660

  5. Surface-initiated atom transfer radical polymerization from chitin nanofiber macroinitiator film.

    Science.gov (United States)

    Yamamoto, Kazuya; Yoshida, Sho; Kadokawa, Jun-Ichi

    2014-11-01

    This paper reports the preparation of chitin nanofiber-graft-poly(2-hydroxyethyl acrylate) (CNF-g-polyHEA) films by surface-initiated atom transfer radical polymerization (ATRP) of HEA monomer from a CNF macroinitiator film. First, a CNF film was prepared by regeneration from a chitin ion gel with an ionic liquid. Then, acylation of the CNF surface with ?-bromoisobutyryl bromide was carried out to obtain the CNF macroinitiator film having the initiating moieties (?-bromoisobutyrate group). The surface-initiated graft polymerization of HEA from the CNF macroinitiator film by ATRP was performed to produce the CNF-g-polyHEA film. The IR, XRD, and SEM measurements of the resulting film indicated the progress of the graft polymerization of HEA on surface of CNFs. The molecular weights of the grafted polyHEAs increased with prolonged polymerization times, which affected the mechanical properties of the films under tensile mode. PMID:25129725

  6. Gas Composition Sensing Using Carbon Nanotube Arrays

    Science.gov (United States)

    Li, Jing; Meyyappan, Meyya

    2012-01-01

    This innovation is a lightweight, small sensor for inert gases that consumes a relatively small amount of power and provides measurements that are as accurate as conventional approaches. The sensing approach is based on generating an electrical discharge and measuring the specific gas breakdown voltage associated with each gas present in a sample. An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multi-wall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the tips for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensor can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

  7. Electrostatic deposition of nanofibers for sensor application

    Scientific Electronic Library Online (English)

    Ana Neilde Rodrigues da, Silva; Rogerio, Furlan; Idalia, Ramos; Jorge Juan, Santiago-Avilés.

    2005-03-01

    Full Text Available SciELO Brazil | Language: English Abstract in english This work addresses the formation of nanofibers (with hundred of nanometers) by using electrospinning (electrostatic deposition) aiming at applications as sensors. Different quantities of a colloidal dispersion of graphite particles were blended with polyacrylonitrile (PAN) and N,N dimethylformamide [...] (DMF), resulting in a series of solutions with carbon concentrations ranging from 0 to 25%. Precipitation was observed depending on the concentration of carbon added to the precursor blend. As a consequence, the relative viscosity decreases, due to PAN molecules removal from the solution by carbon particles adsorption, forming precipitates. The resulting fibers show an irregular shape, as observed by SEM and the diameters decrease with the increase of the carbon concentration in the precursor blend. The incorporation of carbon particles in the fibers was confirmed by FTIRS and Raman spectroscopy.

  8. Electrostatic deposition of nanofibers for sensor application

    Directory of Open Access Journals (Sweden)

    Ana Neilde Rodrigues da Silva

    2005-03-01

    Full Text Available This work addresses the formation of nanofibers (with hundred of nanometers by using electrospinning (electrostatic deposition aiming at applications as sensors. Different quantities of a colloidal dispersion of graphite particles were blended with polyacrylonitrile (PAN and N,N dimethylformamide (DMF, resulting in a series of solutions with carbon concentrations ranging from 0 to 25%. Precipitation was observed depending on the concentration of carbon added to the precursor blend. As a consequence, the relative viscosity decreases, due to PAN molecules removal from the solution by carbon particles adsorption, forming precipitates. The resulting fibers show an irregular shape, as observed by SEM and the diameters decrease with the increase of the carbon concentration in the precursor blend. The incorporation of carbon particles in the fibers was confirmed by FTIRS and Raman spectroscopy.

  9. Application of Nanofiber Technology to Nonwoven Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Phillip W. Gibson, Ph.D

    2007-07-01

    Full Text Available Nanofiber technology (fiber diameter less than 1 micrometer is under development for future Army lightweight protective clothing systems. Nanofiber applications for ballistic and chemical/biological protection are being actively investigated, but the thermal properties of nanofibers and their potential protection against cold environments are relatively unknown. Previous studies have shown that radiative heat transfer in fibrous battings is minimized at fiber diameters between 5 and 10 micrometers. However, the radiative heat transfer mechanism of extremely small diameter fibers of less than 1 micrometer diameter is not well known. Previous studies were limited to glass fibers, which have a unique set of thermal radiation properties governed by the thermal emissivity properties of glass. We are investigating the thermal transfer properties of high loft nanofiber battings composed of carbon fiber and various polymeric fibers such as polyacrylonitrile, nylon, and polyurethane. Thermal insulation battings incorporating nanofibers could decrease the weight and bulk of current thermal protective clothing, and increase mobility for soldiers in the battlefield.

  10. Preparation of MnO nanofibers by novel hydrothermal treatment of manganese acetate/PVA electrospun nanofiber mats

    International Nuclear Information System (INIS)

    In the present study, manganese monoxide (MnO) which is hard to prepare because of the chemical activity of the manganese metal has been synthesized in nanofibrous form. An electrospun manganese acetate/poly(vinyl alcohol) nanofiber mats have been hydrothermally treated by novel strategy. The treatment process was based on producing of water gas (Co and H2) to eliminate the polymer and reduced the manganese acetate to manganese monoxide. The process was carried out by heating the dried nanofiber mates at 400 deg. C for 3 h in an especial designed reactor in which a stream of water vapor was passing through a bed of an activated carbon. The obtained physiochemical characterization results indicated that the proposed hydrothermal treatment process does have the ability to produce pure MnO nanofibers with good crystallinity.

  11. Investigating Impact of The Interfacial Debonding on The Mechanical Propertiesof NanoFiber Reinforced Composites

    Directory of Open Access Journals (Sweden)

    Waleed.K. Ahmed

    2014-01-01

    Full Text Available This work investigates the influence of the interfacial debonding in a nanofiber reinforced composite on the mechanical properties. Mainly, three dimensional-axisymmetric finite element analysis is adopted to study a representative volume element (RVE which is consist of carbon nanofiber confined by a polymeric matrix and subjected to axial tension. Besides, a longitudinal interfacial debonding is imposed along the interfacial nanofiber/matrix. The result of the FEA demonstrate a significant impact of the interfacial debonding on the Young’s modulus of the nanocomposite.

  12. New High-Energy Nanofiber Anode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangwu; Fedkiw, Peter; Khan, Saad; Huang, Alex; Fan, Jiang

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 ?m or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. • During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; • In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; • At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  13. Mechanism of nanofiber crimp

    Directory of Open Access Journals (Sweden)

    Chen Rou-Xi

    2013-01-01

    Full Text Available Fabrication of crimped fibers has been caught much attention recently due to remarkable improvement surface-to-volume ratio. The precise mechanism of the fiber crimp is, however, rare and preliminary. This paper finds that pulsation of fibers is the key factor for fiber crimp, and its configuration (wave formation corresponds to its nature frequency after solidification. Crimping performance can be improved by temperature control of the uncrimped fibers. In the paper, polylactide/ dimethylfomamide solution is fabricated into crimped nanofibers by the bubble electrospinning, an approximate period- amplitude relationship of the wave formation is obtained.

  14. Quasi one dimensional transport in individual electrospun composite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Avnon, A., E-mail: avnon@phys.fu-berlin.de; Datsyuk, V.; Trotsenko, S. [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Wang, B.; Zhou, S. [Research Center of Microperipheric Technologies, Technische Universität Berlin, TiB4/2-1, Gustav-Meyer-Allee 25, 13355 Berlin (Germany); Grabbert, N.; Ngo, H.-D. [Microsystem Engineering (FB I), University of Applied Sciences, Wilhelminenhofstr. 74 (C 525), 12459 Berlin (Germany)

    2014-01-15

    We present results of transport measurements of individual suspended electrospun nanofibers Poly(methyl methacrylate)-multiwalled carbon nanotubes. The nanofiber is comprised of highly aligned consecutive multiwalled carbon nanotubes. We have confirmed that at the range temperature from room temperature down to ?60 K, the conductance behaves as power-law of temperature with an exponent of ? ? 2.9?10.2. The current also behaves as power law of voltage with an exponent of ? ? 2.3?8.6. The power-law behavior is a footprint for one dimensional transport. The possible models of this confined system are discussed. Using the model of Luttinger liquid states in series, we calculated the exponent for tunneling into the bulk of a single multiwalled carbon nanotube ?{sub bulk} ? 0.06 which agrees with theoretical predictions.

  15. Hydrogen storage in graphite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M. [Northeastern Univ., Boston, MA (United States). Chemistry Dept.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  16. Oxolane-2,5-dione modified electrospun cellulose nanofibers for heavy metals adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Stephen, Musyoka [University of Kwazulu-Natal, Private Bag X54001, Westville Durban 4000 (South Africa); Catherine, Ngila, E-mail: jcngila2002@yahoo.com [University of Kwazulu-Natal, Private Bag X54001, Westville Durban 4000 (South Africa); University of Johannesburg, Department of Chemical Technology, P.O Box 17011, Doornfontein 2028, Johannesburg (South Africa); Brenda, Moodley; Andrew, Kindness [University of Kwazulu-Natal, Private Bag X54001, Westville Durban 4000 (South Africa); Leslie, Petrik [Environmental and NanoScience Lab, Department of Chemistry, Faculty of Science, University of Western Cape, Private Bag X17, Bellville 7535 (South Africa); Corrine, Greyling [Cape Organic Chemical Optimization (Pty) Ltd 9 Avenue de Mist, Claremont 7708 (South Africa)

    2011-08-30

    Highlights: {yields} Electrospun and modified cellulose nanofibers have high surface area. {yields} Modified nanofibers showed improved adsorption of Cd and Pb from water. {yields} Regenerated modified nanofibers had high adsorption capacity hence recyclable. - Abstract: Functionalized cellulose nanofibers have been obtained through electrospinning and modification with oxolane-2,5-dione. The application of the nanofibers for adsorption of cadmium and lead ions from model wastewater samples is presented for the first time. Physical and chemical properties of the nanofibers were characterized. Surface chemistry during preparation and functionalization was monitored using Fourier transform-infrared spectroscopy, scanning electron microscopy, carbon-13 solid state nuclear magnetic resonance spectroscopy and Brunauer Emmett and Teller. Enhanced surface area of 13.68 m{sup 2} g{sup -1} was recorded for the nanofibers as compared to the cellulose fibers with a surface area of 3.22 m{sup 2} g{sup -1}. Freundlich isotherm was found to describe the interactions better than Langmuir: K{sub f} = 1.0 and 2.91 mmol g{sup -1} (r{sup 2} = 0.997 and 0.988) for lead and cadmium, respectively. Regenerability of the fiber mats was investigated and the results obtained indicate sustainability in adsorption efficacy of the material.

  17. Oxolane-2,5-dione modified electrospun cellulose nanofibers for heavy metals adsorption

    International Nuclear Information System (INIS)

    Highlights: ? Electrospun and modified cellulose nanofibers have high surface area. ? Modified nanofibers showed improved adsorption of Cd and Pb from water. ? Regenerated modified nanofibers had high adsorption capacity hence recyclable. - Abstract: Functionalized cellulose nanofibers have been obtained through electrospinning and modification with oxolane-2,5-dione. The application of the nanofibers for adsorption of cadmium and lead ions from model wastewater samples is presented for the first time. Physical and chemical properties of the nanofibers were characterized. Surface chemistry during preparation and functionalization was monitored using Fourier transform-infrared spectroscopy, scanning electron microscopy, carbon-13 solid state nuclear magnetic resonance spectroscopy and Brunauer Emmett and Teller. Enhanced surface area of 13.68 m2 g-1 was recorded for the nanofibers as compared to the cellulose fibers with a surface area of 3.22 m2 g-1. Freundlich isotherm was found to describe the interactions better than Langmuir: Kf = 1.0 and 2.91 mmol g-1 (r2 = 0.997 and 0.988) for lead and cadmium, respectively. Regenerability of the fiber mats was investigated and the results obtained indicate sustainability in adsorption efficacy of the material.

  18. Ultrahigh Transmission Optical Nanofibers

    CERN Document Server

    Hoffman, J E; Grover, J A; Solano, P; Kordell, P R; Wong-Campos, J D; Orozco, L A; Rolston, S L

    2014-01-01

    We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 $ \\pm$ 0.02%, which represents a loss from tapering of 2.6 $\\,\\times \\,$ 10$^{-5}$ dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 $\\pm$ 2.8%, which has a loss from tapering of 5.0 $\\,\\times \\,$ 10$^{-4}$ dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported...

  19. Electrospun Nanofiber-Coated Membrane Separators for Lithium-Ion Batteries

    Science.gov (United States)

    Lee, Hun

    Lithium-ion batteries are widely used as a power source for portable electronic devices and hybrid electric vehicles due to their excellent energy and power densities, long cycle life, and enhanced safety. A separator is considered to be the critical component in lithium-ion rechargeable batteries. The separator is placed between the positive and negative electrodes in order to prevent the physical contact of electrodes while allowing the transportation of ions. In most commercial lithium-ion batteries, polyolefin microporous membranes are commonly used as the separator due to their good chemical stability and high mechanical strength. However, some of their intrinsic natures, such as low electrolyte uptake, poor adhesion property to the electrodes, and low ionic conductivity, can still be improved to achieve higher performance of lithium-ion batteries. In order to improve these intrinsic properties, polyolefin microporous membranes can be coated with nanofibers by using electrospinning technique. Electrospinning is a simple and efficient method to prepare nanofibers which can absorb a significant amount of liquid electrolyte to achieve low internal resistance and battery performance. This research presents the preparation and investigation of composite membrane separators prepared by coating nanofibers onto polyolefin microporous membranes via electrospinning technique. Polyvinylidene fluoride polymers and copolymers were used for the preparation of electrospun nanofiber coatings because they have excellent electrochemical stability, good adhesion property, and high temperature resistance. The nanofiber coatings prepared by electrospinning form an interconnected and randomly orientated structure on the surface of the polyolefin microporous membranes. The size of the nanofibers is on a scale that does not interfere with the micropores in the membrane substrates. The resultant nanofiber-coated membranes have the potential to combine advantages of both the polyolefin separator membranes and the nanoscale fibrous polymer coatings. The polyolefin microporous membranes serve as the supporting substrate which provides the required mechanical strength for the assembling process of lithium-ion batteries. The electrospun nanofiber coatings improve the wettability of the composite membrane separators to the liquid electrolyte, which is desirable for the lithium-ion batteries with high kinetics and good cycling performance. The results show that the nanofiber-coated membranes have enhanced adhesion properties to the battery electrode which can help prevent the formation of undesirable gaps between the separators and electrodes during prolonged charge-discharge cycles, especially in large-format batteries. The improvement on adhesive properties of nanofiber-coated membranes was evaluated by peel test. Nanofiber coatings applied to polyolefin membrane substrates improve the adhesion of separator membranes to battery electrodes. Electrolyte uptakes, ionic conductivities and interfacial resistances of the nanofiber-coated membrane separators were studied by soaking the membrane separators with a liquid electrolyte solution of 1 M lithium hexafluorophosphate dissolved in ethylene carbonate/dimethylcarbonate/ethylmethyl carbonate (1:1:1 vol). The nanofiber coatings on the surface of the membrane substrates increase the electrolyte uptake capacity due to the high surface area and capillary effect of nanofibers. The nanofiber-coated membranes soaked in the liquid electrolyte solution exhibit high ionic conductivities and low interfacial resistances to the lithium electrode. The cells containing LiFePO 4 cathode and the nanofiber-coated membranes as the separator show high discharge specific capacities and good cycling stability at room temperature. The nanofiber coatings on the membrane substrates contribute to high ionic conductivity and good electrochemical performance in lithium-ion batteries. Therefore, these nanofiber-coated composite membranes can be directly used as novel battery separators for high performance of lithium-ion batter

  20. Polymeric Nanofibers in Tissue Engineering

    OpenAIRE

    Dahlin, Rebecca L.; Kasper, F. Kurtis; Mikos, Antonios G.

    2011-01-01

    Polymeric nanofibers can be produced using methods such as electrospinning, phase separation, and self-assembly, and the fiber composition, diameter, alignment, degradation, and mechanical properties can be tailored to the intended application. Nanofibers possess unique advantages for tissue engineering. The small diameter closely matches that of extracellular matrix fibers, and the relatively large surface area is beneficial for cell attachment and bioactive factor loading. This review will ...

  1. COAL REINFORCED COMPOSITE POLYAMIDE NANOFIBERS

    OpenAIRE

    Keskin, R.; Gocek, I.; Sahin, U. K.; Berkalp, O. B.; Acarkan, N.; Ozkan, S.; Dikmen, C. D.; Daskaya, E.; Saglam, H.

    2013-01-01

    Polymer nanocomposites are novel classes of composite materials derived from nanoparticles with at least one dimension in the nanometric range. Nanofibers that are produced by electrospinning process have a wide range of use in different textile applications including medical textiles, filtration textiles, protective clothing, as well as coatings for various purposes [1-4]. The aim of this study is to design and develop nanosized coal reinforced composite polyamide (PA) nanofibers by electros...

  2. The formation of titanium dioxide crystallite nanoparticles during activation of PAN nanofibers containing titanium isopropoxide

    International Nuclear Information System (INIS)

    Activated carbon (AC) can act as an important carrier for TiO2 nanoparticles. TiO2 nanoparticle can be fabricated by the hydrolysis and condensation of titanium alkoxides like titanium isopropoxide. This study showed that the formation of titanium dioxide crystallite nanoparticle during activation of PAN nanofibers containing titanium isopropoxide leads to the formation of mainly anatase crystal TiO2 nanoparticle in AC nanofibers, with a good dispersion in both the longitude and cross section of nanofibers. The TiO2 crystallite size lies in the range of 7.3–11.3 nm. The dispersion of TiO2 nanoparticles in the matrix of AC nanofibers is far superior to the direct mixing of TiO2 nanoparticles in the original electrospinning solution.

  3. Superhydrophobic terpolymer nanofibers containing perfluoroethyl alkyl methacrylate by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz, Ugur, E-mail: ucengiz@gyte.edu.tr [Department of Chemical Engineering, Gebze Institute of Technology, Cayirova, 41400 Kocaeli (Turkey); Avci, Merih Z. [Polymer Science and Technology, Deparment of Chemistry, Istanbul Technical University, Maslak 34469, Istanbul (Turkey); Erbil, H. Yildirim [Department of Chemical Engineering, Gebze Institute of Technology, Cayirova, 41400 Kocaeli (Turkey); Sarac, A. Sezai [Polymer Science and Technology, Deparment of Chemistry, Istanbul Technical University, Maslak 34469, Istanbul (Turkey)

    2012-05-15

    A new statistical terpolymer containing perfluoroethyl alkyl methacrylate (Zonyl-TM), methyl methacrylate and butyl acrylate, poly(Zonyl-TM-ran-MMA-ran-BA) was synthesized in supercritical carbon dioxide at 200 bar and 80 Degree-Sign C using AIBN as an initiator by heterogeneous free radical copolymerization. Nanofibers of this terpolymer were produced by electrospinning from its DMF solution. The structural and thermal properties of terpolymers and electrospun poly(Zonyl-TM-MMA-BA) nanofibers were analyzed using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and differential scanning calorimetry. Nanofiber morphology was investigated by scanning electron microscopy. Electrospun nanofiber layer was found to be superhydrophobic with a water contact angle of 172 {+-} 1 Degree-Sign and highly oleophobic with hexadecane, glycerol and ethylene glycol contact angles of 70 {+-} 1 Degree-Sign , 167 {+-} 1 Degree-Sign and 163 {+-} 1 Degree-Sign respectively. The change of the contact angle results on the electrospun fiber layer and flat terpolymer surfaces by varying feed monomer composition were compared and discussed in the text.

  4. Templates for integrated nanofiber growth

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de

    2011-01-01

    Para-hexaphenylene (p6P) molecules have the ability to self-assemble into organic nanofibers. These nanofibers hold unique optoelectronic properties, which make them interesting candidates as elements in electronic and optoelectronic devices. Typically these nanofibers are grown on specific single-crystalline substrates, such as muscovite mica, on which long, mutually parallel nanofibers are self-assembled upon vapor deposition of the organic material under high vacuum conditions. However, the lack of ability to further process these substrates and for integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. In-situ growth constitutes a very promising strategy for integrating functional nanostructures into device platforms due to the possibility of parallel, high-volume integration. Besides such single-crystalline templates, the nanofibers can also be grown on non-crystalline gold surfaces, on which the orientation of the nanofibers can be manipulated by structuring the gold surface prior to p6P deposition. In this work, a novel method for in-situ growth of p6P nanofibers on nano-structured gold surfaces is presented. The substrates are prepared by conventional nanofabrication techniques such as e-beam lithography and metal deposition, which increase their potential as device platforms. Some of the results presented here demonstrate, that both the growth direction and the nanofiber length and position can be controlled by placement of nano-structured lines on the substrate. These lines can be used to guide the surface diffusion and thereby steer the self-assembly process of the organic molecules leading to morphologically well-defined molecular nanofibers with preferred growth directions. It is shown that the preferred growth direction of the nanofibers is perpendicular to these structures whereas their length scales are limited by the size and placement ofthe structures. This work therefore demonstrates a new technique, which can be useful within future organic nanofiber based applications. We also demonstrated how gold gratings fabricated on an insulating substrate can enable electrical contact to in-situ grown p6P nanofibers. In a further development of this method, in-situ directed growth of such organic nanostructures were performed between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (containing bottom- or top-gate) on silicon dioxide. The substrates were patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The transistor design influences its electrical characteristics, and the top-gate configuration shows to have the stronger gate effect. In addition, platforms for light-emitting devices were fabricated, and the nanofibers did emit light when an AC voltage was applied to the gate. Platforms for 4-point measurements were fabricated to eliminate contact resistances and determine the nanofibers intrinsic resistance and resistivity. The large-scale fabrication of such small device platforms was demonstrated by using nano-imprint lithography (NIL). The ability to achieve in-situ growth of p6P nanostructures on device platforms opens a wide range of possible applications including fabrication of organic LEDs and other optoelectronic devices.

  5. Large Scale Synthesis of Carbon Nanofibres on Sodium Chloride Support

    Directory of Open Access Journals (Sweden)

    Ravindra Rajarao

    2012-06-01

    Full Text Available Large scale synthesis of carbon nanofibres (CNFs on a sodium chloride support has been achieved. CNFs have been synthesized using metal oxalate (Ni, Co and Fe as catalyst precursors at 680 ?C by chemical vapour deposition method. Upon pyrolysis, this catalyst precursors yield catalyst nanoparticles directly. The sodium chloride was used as a catalyst support, it was chosen because of its non?toxic and water soluble nature. Problems, such as the detrimental effect of CNFs, the detrimental effects on the environment and even cost, have been avoided by using a water soluble support. The structure of products was characterized by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The purity of the grown products and purified products were determined by the thermal analysis and X?ray diffraction method. Here we report the 7600, 7000 and 6500 wt% yield of CNFs synthesized over nickel, cobalt and iron oxalate. The long, curved and worm shaped CNFs were obtained on Ni, Co and Fe catalysts respectively. The lengthy process of calcination and reduction for the preparation of catalysts is avoided in this method. This synthesis route is simple and economical, hence, it can be used for CNF synthesis in industries.

  6. Nanofibers as novel drug carrier - An overview.

    Science.gov (United States)

    Morie, Asif; Garg, Tarun; Goyal, Amit K; Rath, Goutam

    2014-07-14

    Presently polymer nanofibers have received much attention due to their unique properties such as large surface area, high porosity, small pore size, superior mechanical properties and ease of addition of surface functionalities compared with any other material. Nanofibers particularly polymeric nanofiber prepared by electrospinning process can be used as carriers for the controlled drug delivery of bioactive molecules such as cytokines, growth factors, anticancer drugs, enzymes and certain vitamins. This article presents an overview of nanofibers, various techniques involved in fabrication of nanofibers, their characterization, parameters affecting electrospinning process and their applications. PMID:25016918

  7. Thermo catalytic decomposition of methane over Pd/AC and Pd/CB catalysts for hydrogen production and carbon nanofibers formation

    OpenAIRE

    Srilatha, K.; Srinivasulu, D.

    2014-01-01

    Hydrogen production studies have been carried using Thermo Catalytic Decomposition (TCD) Unit. Thermo catalytic decomposition of methane is an attractive route for COx free production of hydrogen required in fuel cells. Although metal based catalysts produce hydrogen at low temperatures, carbon formed during methane decomposition reaction rapidly deactivates the catalyst. The present work compares the results of 10 wt% Pd supported on commercially available activated carbon an...

  8. Graphitised carbon nanofibres as catalyst support for PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Rantala, E.; Pasanen, A.; Kauranen, P. [VTT Technical Research Centre of Finland, P. O. Box 1300, FI-33101 Tampere (Finland); Ruiz, V.; Borghei, M.; Kauppinen, E. [Department of Applied Physics, Aalto University, P. O. Box 15100, FI-00076 Aalto (Finland); Oyarce, A.; Lindbergh, G.; Lagergren, C. [Royal Institute of Technology, Teknikringen 42, SE-10044 Stockholm (Sweden); Darab, M.; Sunde, S. [Norwegian University of Science and Technology, Sem Saelands vei 12, NO-7495 Trondheim (Norway); Thomassen, M. [SINTEF, Strindveien 4, NO-7465 Trondheim (Norway); Ma-Andersen, S.; Skou., E. [University of Southern Denmark, Campusvej 55, DK-5230 Odense (Denmark)

    2011-12-15

    Graphitised carbon nanofibres (G-CNFs) show superior thermal stability and corrosion resistance in PEM fuel cell environment over traditional carbon black (CB) and carbon nanotube catalyst supports. However, G-CNFs have an inert surface with only very limited amount of surface defects for the anchorage of Pt catalyst nanoparticles. Modification of the fibre surface is therefore needed. In this study Pt nanoparticles have been deposited onto as-received and surface-modified G-CNFs. The surface modifications of the fibres comprise acid treatment and nitrogen doping by pyrolysis of a polyaniline (PANI) precursor. The modified surfaces were studied by FTIR and XPS and the electrochemical characterization, including long-term Pt stability tests, was performed using a low-temperature PEMFC single cell. The performance and stability of the G-CNF supported catalysts were compared with a CB supported catalyst and the effects of the different surface treatments were discussed. On the basis of these results, new membrane electrode assemblies (MEAs) were manufactured and tested also for carbon corrosion by in situ FTIR analysis of the cathode exhaust gases. It was observed that the G-CNFs showed 5 times lower carbon corrosion compared to CB based catalyst when potential reached 1.5 V versus RHE in simulated start/stop cycling. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Graphitised Carbon Nanofibres as Catalyst Support for PEMFC

    DEFF Research Database (Denmark)

    Yli-Rantala, E.; Pasanen, A.

    2011-01-01

    Graphitised carbon nanofibres (G-CNFs) show superior thermal stability and corrosion resistance in PEM fuel cell environment over traditional carbon black (CB) and carbon nanotube catalyst supports. However, G-CNFs have an inert surface with only very limited amount of surface defects for the anchorage of Pt catalyst nanoparticles. Modification of the fibre surface is therefore needed. In this study Pt nanoparticles have been deposited onto as-received and surface-modified G-CNFs. The surface modifications of the fibres comprise acid treatment and nitrogen doping by pyrolysis of a polyaniline (PANI) precursor. The modified surfaces were studied by FTIR and XPS and the electrochemical characterization, including long-term Pt stability tests, was performed using a low-temperature PEMFC single cell. The performance and stability of the G-CNF supported catalysts were compared with a CB supported catalyst and the effects of the different surface treatments were discussed. On the basis of these results, new membrane electrode assemblies (MEAs) were manufactured and tested also for carbon corrosion by in situ FTIR analysis of the cathode exhaust gases. It was observed that the G-CNFs showed 5?times lower carbon corrosion compared to CB based catalyst when potential reached 1.5?V versus RHE in simulated start/stop cycling.

  10. Thermo catalytic decomposition of methane over Pd/AC and Pd/CB catalysts for hydrogen production and carbon nanofibers formation

    Directory of Open Access Journals (Sweden)

    K. Srilatha

    2014-09-01

    Full Text Available Hydrogen production studies have been carried using Thermo Catalytic Decomposition (TCD Unit. Thermo catalytic decomposition of methane is an attractive route for COx free production of hydrogen required in fuel cells. Although metal based catalysts produce hydrogen at low temperatures, carbon formed during methane decomposition reaction rapidly deactivates the catalyst. The present work compares the results of 10 wt% Pd supported on commercially available activated carbon and carbon black catalysts (samples coded as Pd10/AC and Pd10/CB respectively for methane decomposition reaction. Hydrogen has been produced by thermo catalytic decomposition of methane at 1123K and Volume Hourly Space Velocity (VHSV of 1.62 L/h g on the activity of both the catalysts has been studied. XRD of the above catalysts revealed, moderately crystalline peaks of Pd which may be responsible for the increase in catalytic life and formation of carbon fibers. Also during life studies (850°C and 54 sccm of methane it has been observed that the activity of carbon black is sustainable for a longer time compared to that of activated carbon.

  11. Oriented nanofibers embedded in a polymer matrix

    Science.gov (United States)

    Barrera, Enrique V. (Inventor); Rodriguez-Macias, Fernando J. (Inventor); Lozano, Karen (Inventor); Chibante, Luis Paulo Felipe (Inventor); Stewart, David Harris (Inventor)

    2011-01-01

    A method of forming a composite of embedded nanofibers in a polymer matrix is disclosed. The method includes incorporating nanofibers in a plastic matrix forming agglomerates, and uniformly distributing the nanofibers by exposing the agglomerates to hydrodynamic stresses. The hydrodynamic said stresses force the agglomerates to break apart. In combination or additionally elongational flow is used to achieve small diameters and alignment. A nanofiber reinforced polymer composite system is disclosed. The system includes a plurality of nanofibers that are embedded in polymer matrices in micron size fibers. A method for producing nanotube continuous fibers is disclosed. Nanofibers are fibrils with diameters of 100 nm, multiwall nanotubes, single wall nanotubes and their various functionalized and derivatized forms. The method includes mixing a nanofiber in a polymer; and inducing an orientation of the nanofibers that enables the nanofibers to be used to enhance mechanical, thermal and electrical properties. Orientation is induced by high shear mixing and elongational flow, singly or in combination. The polymer may be removed from said nanofibers, leaving micron size fibers of aligned nanofibers.

  12. 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

  13. Electrospun light-emitting nanofibers.

    Science.gov (United States)

    Moran-Mirabal, José M; Slinker, Jason D; DeFranco, John A; Verbridge, Scott S; Ilic, Rob; Flores-Torres, Samuel; Abruña, Héctor; Malliaras, George G; Craighead, H G

    2007-02-01

    We have electrospun light-emitting nanofibers from ruthenium(II) tris(bipyridine)/polyethylene oxide mixtures. The electroluminescent fibers were deposited on gold interdigitated electrodes and lit in a nitrogen atmosphere. The fibers showed light emission at low operating voltages (3-4 V), with turn-on voltages approaching the band gap limit of the organic semiconductor. Because of the fiber size, emission from electrospun light-emitting nanofibers is confined to nanoscale dimensions, an attractive feature for sensing applications and lab-on-a-chip integration where highly localized excitation of molecules is required. PMID:17243752

  14. Self-Assembled Peptide Nanofibers

    Science.gov (United States)

    Higashi, Nobuyuki; Koga, Tomoyuki

    Molecular self-assembly is a powerful approach being explored for novel supramolecular nanostructures and bio-inspired nanomaterials. In this article, we focus on recent research concerning the self-assembly of de novo designed artificial peptides and peptidomimetics into nanofiber structures, specifically towards developing a new class of soft-materials. These nanofiber architectures have potential use not only in biomedical applications, such as 3D-matrix scaffolds for tissue engineering and biomineralization, but also in nanotechnology such as nano-templates and dimension-regulated functional nano-objects.

  15. Synthesis of carbon fibers with branched nanographene sheets for electrochemical double layer capacitor application.

    Science.gov (United States)

    Matsushima, Masahiro; Kalita, Golap; Kato, Kimitoshi; Noda, Mikio; Uchida, Hideo; Wakita, Koichi; Umeno, Masayoshi; Tanemura, Masaki

    2014-03-01

    We demonstrate a one step technique to synthesis the carbon fibers (CNFs) with branched nanographene sheets by the pulsed discharge (PD) plasma chemical vapor deposition (CVD) process. Highly crystalline branched nanographene sheets were directly grown from the surface of the carbon fibers to obtain a three dimensional (3D) nanostructure. The growth process can be explained from the catalyst support growth of the CNFs, and subsequently nucleation and growth of the nanographene sheets from the crystalline surface of the CNF. The deposited nanostructured films with different pulse discharge were used as an electrode for electrochemical double-layer capacitors (EDLC). It is observed that the capacitance is dependent on the morphology of the electrode materials and an optimum capacitance is obtained with the branched nanographene on CNFs. PMID:24745271

  16. Use of Nanofibers to Strengthen Hydrogels of Silica, Other Oxides, and Aerogels

    Science.gov (United States)

    Meador, Mary Ann B.; Capadona, Lynn A.; Hurwitz, Frances; Vivod, Stephanie L.; Lake, Max

    2010-01-01

    Research has shown that including up to 5 percent w/w carbon nanofibers in a silica backbone of polymer crosslinked aerogels improves its strength, tripling compressive modulus and increasing tensile stress-at-break five-fold with no increase in density or decrease in porosity. In addition, the initial silica hydrogels, which are produced as a first step in manufacturing the aerogels, can be quite fragile and difficult to handle before cross-linking. The addition of the carbon nanofiber also improves the strength of the initial hydrogels before cross-linking, improving the manufacturing process. This can also be extended to other oxide aerogels, such as alumina or aluminosilicates, and other nanofiber types, such as silicon carbide.

  17. End-specific strategies of attachment of long double stranded DNA onto gold-coated nanofiber arrays

    International Nuclear Information System (INIS)

    We report the effective and site-specific binding of long double stranded (ds)DNA to high aspect ratio carbon nanofiber arrays. The carbon nanofibers were first coated with a thin gold layer to provide anchorage for two controllable binding methods. One method was based on the direct binding of thiol end-labeled dsDNA. The second and enhanced method used amine end-labeled dsDNA bound with crosslinkers to a carboxyl-terminated self-assembled monolayer. The bound dsDNA was first visualized with a fluorescent, dsDNA-intercalating dye. The specific binding onto the carbon nanofiber was verified by a high resolution detection method using scanning electron microscopy in combination with the binding of neutravidin-coated fluorescent microspheres to the immobilized and biotinylated dsDNA. Functional activity of thiol end-labeled dsDNA on gold-coated nanofiber arrays was verified with a transcriptional assay, whereby Chinese hamster lung cells (V79) were impaled upon the DNA-modified nanofibers and scored for transgene expression of the tethered template. Thiol end-labeled dsDNA demonstrated significantly higher expression levels than nanofibers prepared with control dsDNA that lacked a gold-binding end-label. Employing these site-specific and robust techniques of immobilization of dsDNA onto nanodevices can be of advantage for the study of DNA/protein interactions and for gene delivery applications.

  18. Effects of freeze drying and silver staining on carbonization of cellulose: carbon nano-materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Young; Im, Hyun Sik [Dongguk University, Seoul (Korea, Republic of)

    2012-05-15

    We investigated the effects of sulfuric acid and silver particles on the carbonization of natural cellulose from Halocynthia. We carried out thermogravimetry and used transmission electron microscopy measurements to study the yield of carbon and the structure of the carbonized nano-fiber. We found that the addition of sulfuric acid and silver particles to the cellulose fiber enhanced the yield of carbon while keeping the original structure of the carbon nano-fiber.

  19. Effects of freeze drying and silver staining on carbonization of cellulose: carbon nano-materials

    International Nuclear Information System (INIS)

    We investigated the effects of sulfuric acid and silver particles on the carbonization of natural cellulose from Halocynthia. We carried out thermogravimetry and used transmission electron microscopy measurements to study the yield of carbon and the structure of the carbonized nano-fiber. We found that the addition of sulfuric acid and silver particles to the cellulose fiber enhanced the yield of carbon while keeping the original structure of the carbon nano-fiber.

  20. Optical microfibers and nanofibers

    Science.gov (United States)

    Wu, Xiaoqin; Tong, Limin

    2013-12-01

    As a combination of fiber optics and nanotechnology, optical microfibers and nanofibers (MNFs) have been emerging as a novel platform for exploring fiber-optic technology on the micro/nanoscale. Typically, MNFs taper drawn from glass optical fibers or bulk glasses show excellent surface smoothness, high homogeneity in diameter and integrity, which bestows these tiny optical fibers with low waveguiding losses and outstanding mechanical properties. Benefitting from their wavelength- or sub-wavelength-scale transverse dimensions, waveguiding MNFs exhibit a number of interesting properties, including tight optical confinement, strong evanescent fields, evident surface field enhancement and large and abnormal waveguide dispersion, which makes them ideal nanowaveguides for coherently manipulating light, and connecting fiber optics with near-field optics, nonlinear optics, plasmonics, quantum optics and optomechanics on the wavelength- or sub-wavelength scale. Based on optical MNFs, a variety of technological applications, ranging from passive micro-couplers and resonators, to active devices such as lasers and optical sensors, have been reported in recent years. This review is intended to provide an up-to-date introduction to the fabrication, characterization and applications of optical MNFs, with emphasis on recent progress in our research group. Starting from a brief introduction of fabrication techniques for physical drawing glass MNFs in Section 2, we summarize MNF optics including waveguiding modes, evanescent coupling, and bending loss of MNFs in Section 3. In Section 4, starting from a "MNF tree" that summarizes the applications of MNFs into 5 categories (waveguide & near field optics, nonlinear optics, plasmonics, quantum & atom optics, optomechanics), we go to details of typical technological applications of MNFs, including optical couplers, interferometers, gratings, resonators, lasers and sensors. Finally in Section 5 we present a brief summary of optical MNFs regarding their current challenges and future opportunities.

  1. Electrospun nanofibers for neural tissue engineering

    Science.gov (United States)

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

    2010-01-01

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

  2. Fabrication of an all SU-8 electrospun nanofiber based supercapacitor

    Science.gov (United States)

    Fee Jao, Pit; Kim, Kyoung Tae; Jung-A Kim, Gloria; Yoon, Yong-Kyu

    2013-11-01

    Supercapacitors (SCs) as energy storage devices are advantageous in their rapid charge/discharge capabilities and their immense charge storage capacity. Two important components of a SC are the electrically conductive electrodes (anode and cathode) and an electrically non-conductive separator between the two electrodes. This paper details a fabrication process for nanofibrous carbon electrodes and a nanoporous polymer separator using all SU-8 based electrospinning and post electrospinning processes, such as lithographical patterning, conversion of the nanofibrous polymer to carbon structures using heat treatment (carbonization) and their assembly to complete a SC. The process produces immensely porous electrodes with good conductivity; it is scalable and economical compared with the carbon nanotube electrode approach. High throughput tube nozzle electrospinning for nanofiber (NF) production and its photolithographical patterning have been employed to facilitate manufacturability. The dependence of the NF morphology on the carbonization temperatures is studied. Also, SC testing and characterization are discussed.

  3. DNA optical nanofibers: preparation and characterization.

    Science.gov (United States)

    Long, Weihong; Zou, Weiwen; Li, Xinwan; Chen, Jianping

    2012-07-30

    We demonstrate the preparation and characterization of DNA optical nanofibers. The prepared DNA optical nanofibers with strong strength and high flexibility are tested. Coupled with silica fiber tapers, their optical characteristics including light transmission performance, group delay and chromatic dispersion are experimentally investigated. The visible and near infrared light waveguiding properties of the DNA optical nanofibers with and without R6G doping are also studied. It is expected that the DNA optical nanofibers may be potential for building the miniaturized biomedical photonic devices. PMID:23038367

  4. Nickel nanofibers synthesized by the electrospinning method

    International Nuclear Information System (INIS)

    Highlights: ? The nickel nanofibers have been obtained by electrospinning method. ? The nickel nanofibers had rough surface which was consisted of mass nanoparticles. ? The average diameter of nickel nanofibers is about 135 nm and high degree of crystallization. ? The Hc, Ms, and Mr were estimated to be 185 Oe, 51.9 and 16.9 emu/g respectively. - Abstract: In this paper, nickel nanofibers were prepared by electrospinning polyvinyl alcohol/nickel nitrate precursor solution followed by high temperature calcination in air and deoxidation in hydrogen atmosphere. The thermal stability of the as-electrospun PVA/Ni(NO3)2 composite nanofibers were characterized by TG–DSC. The morphologies and structures of the as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electronmicroscope (FE-SEM) and field-emission transmission electron microscopy (FE-TEM). The hysteresis loops (M–H loops) were measured by Physical Property Measurement System (PPMS). The results indicate that: the PVA and the nickel nitrate were almost completely decomposed at 460 °C and the products were pure nickel nanofibers with face-centered cubic (fcc) structure. Furthermore, the as-prepared nickel nanofibers had a continuous structure with rough surface and high degree of crystallization. The average diameter of nickel nanofibers was about 135 nm. The nanofibers showed a stronger coercivity of 185 Oe than value of bulk nickel

  5. Electrospun nanofiber scaffolds: engineering soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Kumbar, S G; Nukavarapu, S P; Laurencin, C T [Department of Orthopaedic Surgery, University of Virginia, VA 22908 (United States); James, R [Department of Biomedical Engineering, University of Virginia, VA 22908 (United States)], E-mail: laurencin@virginia.edu

    2008-09-01

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

  6. Nickel nanofibers synthesized by the electrospinning method

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yi [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China); Zhang, Xuebin, E-mail: zzhhxxbb@126.com [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China); Zhu, Yajun; Li, Bin; Wang, Yang; Zhang, Jingcheng; Feng, Yi [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China)

    2013-07-15

    Highlights: ? The nickel nanofibers have been obtained by electrospinning method. ? The nickel nanofibers had rough surface which was consisted of mass nanoparticles. ? The average diameter of nickel nanofibers is about 135 nm and high degree of crystallization. ? The Hc, Ms, and Mr were estimated to be 185 Oe, 51.9 and 16.9 emu/g respectively. - Abstract: In this paper, nickel nanofibers were prepared by electrospinning polyvinyl alcohol/nickel nitrate precursor solution followed by high temperature calcination in air and deoxidation in hydrogen atmosphere. The thermal stability of the as-electrospun PVA/Ni(NO{sub 3}){sub 2} composite nanofibers were characterized by TG–DSC. The morphologies and structures of the as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electronmicroscope (FE-SEM) and field-emission transmission electron microscopy (FE-TEM). The hysteresis loops (M–H loops) were measured by Physical Property Measurement System (PPMS). The results indicate that: the PVA and the nickel nitrate were almost completely decomposed at 460 °C and the products were pure nickel nanofibers with face-centered cubic (fcc) structure. Furthermore, the as-prepared nickel nanofibers had a continuous structure with rough surface and high degree of crystallization. The average diameter of nickel nanofibers was about 135 nm. The nanofibers showed a stronger coercivity of 185 Oe than value of bulk nickel.

  7. High Sensitive Sensor Fabricated by Reduced Graphene Oxide/Polyvinyl Butyral Nanofibers for Detecting Cu (II) in Water.

    Science.gov (United States)

    Ding, Rui; Luo, Zhimin; Ma, Xiuling; Fan, Xiaoping; Xue, Liqun; Lin, Xiuzhu; Chen, Sheng

    2015-01-01

    Graphene oxide (GO)/polyvinyl butyral (PVB) nanofibers were prepared by a simple electrospinning technique with PVB as matrix and GO as a functional nanomaterial. GO/PVB nanofibers on glassy carbon electrode (GCE) were reduced through electrochemical method to form reduced graphene oxide (RGO)/PVB nanofibers. The morphology and structure of GO/PVB nanofiber were studied by scanning election microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR). RGO/PVB modified GCE was used for fabricating an electrochemical sensor for detecting Cu (II) in water. The analysis results showed that RGO/PVB modified GCE had good analytical results with the linear range of 0.06-2.2??M, detection limit of 4.10?nM (S/N = 3), and the sensitivity of 103.51??A·?M(-1)·cm(-2). PMID:25694783

  8. Gas diffusion electrode based on electrospun Pani/CNF nanofibers hybrid for proton exchange membrane fuel cells (PEMFC) applications

    International Nuclear Information System (INIS)

    A novel hybrid system has been investigated based on polyaniline/carbon nanofiber (Pani/CNF) electrospun nanofibers for modification of gas diffusion electrode (GDE) in proton exchange membrane fuel cells (PEMFC). Pani/CNF hybrid nanofibers were synthesized directly on carbon paper by electrospinning method. For preparation of catalyst ink, 20 wt.% Pt/C electrocatalyst with a platinum loading of 0.4 mg cm?2 was prepared by polyol technique. SEM studies applied for morphological study of the modified GDE with hybrid nanofibers. This technique indicated that the electrospun nanofibers had a diameter of roughly 100 nm. XRD patterns also showed that the average size of Pt nanoparticles was about 2 nm. Subsequently, comparison of the hybrid electrode electrochemical behavior and 20 wt.% Pt/C commercial one was studied by cyclic voltammetry experiment. The electrochemical data indicated that the hybrid electrode exhibited higher current density (about 15 mA cm?2) and ESA (160 m2 gr?1) than commercial Pt/C with amount of about 10 mA cm?2 and 114 m2 gr?1, respectively. The results herein demonstrate that Pani/CNF nanofibers can be used as a good alternative electrode material for PEMFCs

  9. Gas diffusion electrode based on electrospun Pani/CNF nanofibers hybrid for proton exchange membrane fuel cells (PEMFC) applications

    Energy Technology Data Exchange (ETDEWEB)

    Hezarjaribi, M.; Jahanshahi, M., E-mail: mjahan@nit.ac.ir; Rahimpour, A.; Yaldagard, M.

    2014-03-01

    A novel hybrid system has been investigated based on polyaniline/carbon nanofiber (Pani/CNF) electrospun nanofibers for modification of gas diffusion electrode (GDE) in proton exchange membrane fuel cells (PEMFC). Pani/CNF hybrid nanofibers were synthesized directly on carbon paper by electrospinning method. For preparation of catalyst ink, 20 wt.% Pt/C electrocatalyst with a platinum loading of 0.4 mg cm{sup ?2} was prepared by polyol technique. SEM studies applied for morphological study of the modified GDE with hybrid nanofibers. This technique indicated that the electrospun nanofibers had a diameter of roughly 100 nm. XRD patterns also showed that the average size of Pt nanoparticles was about 2 nm. Subsequently, comparison of the hybrid electrode electrochemical behavior and 20 wt.% Pt/C commercial one was studied by cyclic voltammetry experiment. The electrochemical data indicated that the hybrid electrode exhibited higher current density (about 15 mA cm{sup ?2}) and ESA (160 m{sup 2} gr{sup ?1}) than commercial Pt/C with amount of about 10 mA cm{sup ?2} and 114 m{sup 2} gr{sup ?1}, respectively. The results herein demonstrate that Pani/CNF nanofibers can be used as a good alternative electrode material for PEMFCs.

  10. Gas diffusion electrode based on electrospun Pani/CNF nanofibers hybrid for proton exchange membrane fuel cells (PEMFC) applications

    Science.gov (United States)

    Hezarjaribi, M.; Jahanshahi, M.; Rahimpour, A.; Yaldagard, M.

    2014-03-01

    A novel hybrid system has been investigated based on polyaniline/carbon nanofiber (Pani/CNF) electrospun nanofibers for modification of gas diffusion electrode (GDE) in proton exchange membrane fuel cells (PEMFC). Pani/CNF hybrid nanofibers were synthesized directly on carbon paper by electrospinning method. For preparation of catalyst ink, 20 wt.% Pt/C electrocatalyst with a platinum loading of 0.4 mg cm-2 was prepared by polyol technique. SEM studies applied for morphological study of the modified GDE with hybrid nanofibers. This technique indicated that the electrospun nanofibers had a diameter of roughly 100 nm. XRD patterns also showed that the average size of Pt nanoparticles was about 2 nm. Subsequently, comparison of the hybrid electrode electrochemical behavior and 20 wt.% Pt/C commercial one was studied by cyclic voltammetry experiment. The electrochemical data indicated that the hybrid electrode exhibited higher current density (about 15 mA cm-2) and ESA (160 m2 gr-1) than commercial Pt/C with amount of about 10 mA cm-2 and 114 m2 gr-1, respectively. The results herein demonstrate that Pani/CNF nanofibers can be used as a good alternative electrode material for PEMFCs.

  11. Surface modified carbon nanoparticle papers and applications on polymer composites

    Science.gov (United States)

    Ouyang, Xilian

    Free-standing paper like materials are usually employed as protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, and electronic or optoelectric components. Free-standing papers made from carbon nanoparticles have drawn increased interest because they have a variety of superior chemical and physical characteristics, such as light weight, high intrinsic mechanical properties, and extraordinary high electrical conductivity. Nanopapers fabricated from 1- D shape carbon nanofibers (CNFs) and carbon nanotubes (CNTs) are promising reinforcing materials for polymer composites, because the highly porous CNF and CNT nanopapers (porosity ˜80% and ˜70% respectively) can be impregnated with matrix polymers. In the first part of this work, polyaniline (PANI) was used to functionalize the surface of CNFs, and the resultant carbon nanopapers presented impressive mechanical strength and electrical conductivity that it could be used in the in-mold coating (IMC)/ injection molding process to achieve high electromagnetic interference (EMI) shielding effectiveness. Aniline modified (AF) CNT nanopapers were used as a 3D network in gas separation membranes. The resultant composite membranes demonstrated better and stable CO2 permeance and CO 2/H2 selectivity in a high temperature (107°C) and high pressure (15-30 atm) gas separation process, not achievable by conventional polymer membranes. In the second part, we demonstrated that 2-D graphene (GP) or graphene oxide (GO) nanosheets could be tightly packed into a film which was impermeable to most gases and liquids. GP or GO nanopapers could be coated on polymer composites. In order to achieve well-dispersed single-layer graphene in aqueous medium, we developed a facile approach to synthesize functional GP bearing benzenesulfonic acid groups which allow the preparation of nanopapers by water based assembly. With the optimized processing conditions, our best GP nanopapers could reach a tensile strength of 360 MPa and an electrical conductivity of 4.45x104 S/m, much better than any similar materials reported in the literature. However, they didn't show good gas barrier properties. Since the GO paper presented zero gas permeability for both CO2 and H2, a hybrid paper fabrication approach was proposed to combine the advantages of individual GP and GO papers. This was done by filtering GP and GO layer by layer with GO sandwiched in between two layers of GP. The resulting hybrid papers showed high mechanical tensile strength and EMI shielding effectiveness that are close to GP nanopapers, and excellent gas barrier properties that comparable to GO nanopapers. The GP, GO and GP-Go-GP hybrid nanopapers have been successfully coated onto the thermoplastic surface by thermal lamination and injection molding. In the third part, the effect of PANI-CNF nanopapers and a chelating agent, 2, 4- Pentanedione (2, 4-P) on kinetics of an in-mold coating (IMC) resin was investigated. The results showed that the presence of amine functionalized carbon nanoparticles tended to retard the resin reaction, while 2, 4-P was capable of promoting the redox based free radical polymerization by forming a complex with the cobalt promoter in the initiation step. In order to understand the chemical and physical changes during the resin curing process, kinetics study on two major resin components, i.e. hexanediol diacrylate (HDDA) and styrene (St), were carried out using an integrated analysis design: differential scanning calorimetry (DSC) for overall reaction, Fourier transform infrared spectroscopy (FTIR) for individual component reactions, and rheometry for liquid-solid transition during the reaction. The gel point of this radical polymerization resin system was found to be <2% which implied that most curing was conducted in the solid phase. The results showed that the double bonds in acrylates and St followed an azeotropic polymerization pattern.

  12. Preparation and photoluminescence characteristics of Tb-, Sm- and Dy-doped Y{sub 2}O{sub 3} nanofibers by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaoyan; Chen Yuming [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Qian Qingrong, E-mail: qrqian@fjnu.edu.cn [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Liu Xinping; Xiao Liren [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China); Chen Qinghua, E-mail: cqhuar@pub5.fz.fj.cn [College of Chemistry and Materials Science, College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007 (China); Fujian Modified Plastic Institute of Research and Technology Development, Fuzhou 350007 (China); Fujian Engineering Research Center of Environment-friendly Polymer Material, Fuzhou 350007 (China)

    2012-01-15

    An electrospinning-calcination strategy was established to fabricate Y{sub 2}O{sub 3} nanofibers doped with rare earth ions (Tb, Sm and Dy) using electrospun PVA/RE(NO{sub 3}){sub x}/Y(NO{sub 3}){sub 3} composite nanofibers as precursors (x=3.4). The prepared nanofibers were characterized by XRD, FESEM, EDS, (HR)TEM and PL analyses. Based on the experimental results, a solid-solid growth mechanism (SS) was proposed to describe the formation of inorganic crystalline fibers from organic/inorganic composite nanofibers by calcination. It was determined that carbonaceous nanoparticles that were formed in the process of pre-carbonization adsorbed Y{sub 2}O{sub 3}:RE nanoparticles to grow Y{sub 2}O{sub 3}:RE crystal, and the resultant nanofibers exhibited a typical crystalline domain with grain boundary. The obtained Y{sub 2}O{sub 3}:RE nanofibers possessed excellent luminescent characteristics and could be used as an appreciable luminescent material. - Highlights: > Fabricate Y{sub 2}O{sub 3}:RE fibers by the calcination of electrospun PVA/Y(NO{sub 3}){sub 3}/RE(NO{sub 3}){sub 3} composite nanofibers. > Prepared Y{sub 2}O{sub 3}:RE nanofibers display more intensive photoluminescence performance than the bulk materials. > Propose a solid-solid growth mechanism for the formation of inorganic crystalline fibers via calciation.

  13. Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers

    Science.gov (United States)

    Jain, Rahul

    The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to increase the concentration of CNTs as much as possible to make next generation multi-functional materials. The work in this thesis is mainly focused on MWNT and CNF reinforced polyacrylonitrile (PAN) composite fibers, and SWNT, FWNT, and MWNT reinforced poly(etherketone) (PEK) composite fibers. To the best of our knowledge, this is the first study to report the spinning of 20% MWNT or 30% CNF reinforced polymer fiber spun using conventional fiber spinning. Also, this is the first study to report the PEK/CNT composite fibers. The fibers were characterized for their thermal, tensile, mechanical, and dynamic mechanical properties. The fiber structure and morphology was studied using WAXD and SEM. The effect of two-stage heat drawing, sonication time for CNF dispersion, fiber drying temperature, and molecular weight of PAN was also studied. Other challenges associated with processing high concentrations of solutions for making composite fibers have been identified and reported. The effect of CNT diameter and concentration on fiber spinnability and electrical conductivity of composite fiber have also been studied. This work suggests that CNT diameter controls the maximum possible concentration of CNTs in a composite fiber. The results show that by properly choosing the type of CNT, length of CNTs, dispersion of CNTs, fiber spinning method, fiber draw ratio, and type of polymer, one can get electrically conducting fibers with wide range of conductivities for different applications. The PEK based control and composite fibers possess high thermal stability with almost no weight loss up to 500°C and negligible thermal shrinkage up to 200°C. The PEK based fibers showed high toughness which surpassed many of the high-performance fibers like KevlarRTM and Zylon RTM. The 10% FWNT containing fiber is unique in terms of high electrical conductivity and high toughness. The CNT based fibers may be used as structural material, fire-barrier/protection textile, electrode for electrochemical capacitor or fuel cells, and as a template for directional growth of tissues.

  14. On-chip microplasma reactors using carbon nanofibres and tungsten oxide nanowires as electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Agiral, Anil; Groenland, Alfons W; Han Gardeniers, J G E [Mesoscale Chemical Systems, MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands); Chinthaginjala, J Kumar; Seshan, K; Lefferts, Leon [Catalytic Processes and Materials, MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)], E-mail: a.agiral@utwente.nl

    2008-10-07

    Carbon nanofibres (CNFs) and tungsten oxide (W{sub 18}O{sub 49}) nanowires have been incorporated into a continuous flow type microplasma reactor to increase the reactivity and efficiency of the barrier discharge at atmospheric pressure. CNFs and tungsten oxide nanowires were characterized by high-resolution scanning electron microscopy, transmission electron microscopy and nanodiffraction methods. Field emission of electrons from those nanostructures supplies free electrons and ions during microplasma production. Reduction in breakdown voltage, higher number of microdischarges and higher energy deposition were observed at the same applied voltage when compared with plane electrodes at atmospheric pressure in air. Rate coefficients of electron impact reaction channels to decompose CO{sub 2} were calculated and it was shown that CO{sub 2} consumption increased using CNFs compared with plane electrode in the microplasma reactor.

  15. On-chip microplasma reactors using carbon nanofibres and tungsten oxide nanowires as electrodes

    International Nuclear Information System (INIS)

    Carbon nanofibres (CNFs) and tungsten oxide (W18O49) nanowires have been incorporated into a continuous flow type microplasma reactor to increase the reactivity and efficiency of the barrier discharge at atmospheric pressure. CNFs and tungsten oxide nanowires were characterized by high-resolution scanning electron microscopy, transmission electron microscopy and nanodiffraction methods. Field emission of electrons from those nanostructures supplies free electrons and ions during microplasma production. Reduction in breakdown voltage, higher number of microdischarges and higher energy deposition were observed at the same applied voltage when compared with plane electrodes at atmospheric pressure in air. Rate coefficients of electron impact reaction channels to decompose CO2 were calculated and it was shown that CO2 consumption increased using CNFs compared with plane electrode in the microplasma reactor.

  16. All-textile flexible supercapacitors using electrospun poly(3,4-ethylenedioxythiophene) nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Laforgue, Alexis [Functional Polymer Systems Group, Industrial Materials Institute, National Research Council Canada, 75, de Mortagne Blvd, Boucherville, Quebec J4B 6Y4 (Canada)

    2011-01-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers were obtained by the combination of electrospinning and vapor-phase polymerization. The fibers had diameters around 350 nm, and were soldered at most intersections, providing a strong dimensional stability to the mats. The nanofiber mats demonstrated very high conductivity (60 {+-} 10 S cm{sup -1}, the highest value reported so far for polymer nanofibers) as well as improved electrochemical properties, due to the ultraporous nature of the electrospun mats. The mats were incorporated into all-textile flexible supercapacitors, using carbon cloths as the current collectors and electrospun polyacrylonitrile (PAN) nanofibrous membranes as the separator. The textile layers were stacked and embedded in a solid electrolyte containing an ionic liquid and PVDF-co-HFP as the host polymer. The resulting supercapacitors were totally flexible and demonstrated interesting and stable performances in ambient conditions. (author)

  17. A novel hydrogen peroxide biosensor based on hemoglobin-collagen-CNTs composite nanofibers.

    Science.gov (United States)

    Li, J; Mei, H; Zheng, W; Pan, P; Sun, X J; Li, F; Guo, F; Zhou, H M; Ma, J Y; Xu, X X; Zheng, Y F

    2014-06-01

    In this paper, carbon nanotubes (CNTs) were successfully incorporated in the composite composed of hemoglobin (Hb) and collagen using co-electrospinning technology. The formed Hb-collagen-CNTs composite nanofibers possessed distinct advantage of three-dimensional porous structure, biocompatibility and excellent stability. The Hb immobilized in the electrospun nanofibers retained its natural structure and the heterogeneous electron transfer rate constant (ks) of the direct electron transfer between Hb and electrodes was 5.3s(-1). In addition, the electrospun Hb-collagen-CNTs nanofibers modified electrodes showed good electrocatalytic properties toward H2O2 with a detection limit of 0.91?M (signal-to-noise ratio of 3) and the apparent Michaelis-Menten constant (Km(app)) of 32.6?M. PMID:24732396

  18. High-cooperativity nanofiber laser

    OpenAIRE

    Faez, Sanli; Tu?rschmann, Pierre; Sandoghdar, Vahid

    2014-01-01

    Cavity-free efficient coupling between emitters and guided modes is of great current interest for nonlinear quantum optics as well as efficient and scalable quantum information processing. In this work, we extend these activities to the coupling of organic dye molecules to a highly confined mode of a nanofiber, allowing mirrorless and low-threshold laser action in an effective mode volume of less than 100 femtoliters. We model this laser system based on semi-classical rate e...

  19. Antibacterial properties of laser spinning glass nanofibers.

    Science.gov (United States)

    Echezarreta-López, M M; De Miguel, T; Quintero, F; Pou, J; Landin, M

    2014-12-30

    A laser-spinning technique has been used to produce amorphous, dense and flexible glass nanofibers of two different compositions with potential utility as reinforcement materials in composites, fillers in bone defects or scaffolds (3D structures) for tissue engineering. Morphological and microstructural analyses have been carried out using SEM-EDX, ATR-FTIR and TEM. Bioactivity studies allow the nanofibers with high proportion in SiO2 (S18/12) to be classified as a bioinert glass and the nanofibers with high proportion of calcium (ICIE16) as a bioactive glass. The cell viability tests (MTT) show high biocompatibility of the laser spinning glass nanofibers. Results from the antibacterial activity study carried out using dynamic conditions revealed that the bioactive glass nanofibers show a dose-dependent bactericidal effect on Sthaphylococcus aureus (S. aureus) while the bioinert glass nanofibers show a bacteriostatic effect also dose-dependent. The antibacterial activity has been related to the release of alkaline ions, the increase of pH of the medium and also the formation of needle-like aggregates of calcium phosphate at the surface of the bioactive glass nanofibers which act as a physical mechanism against bacteria. The antibacterial properties give an additional value to the laser-spinning glass nanofibers for different biomedical applications, such as treating or preventing surgery-associated infections. PMID:25447823

  20. Growth of Graphene Nanoribbons and Carbon Onions from Polymer

    Science.gov (United States)

    Guo, Xiao-Song; Lu, Bing-An; Xie, Er-Qing

    2011-07-01

    Graphene nanoribbons and carbon onions are directly prepared by electron beam irradiation of polyacrylonitrile and expanded polystyrene nanofibers, respectively. By controlling the irradiation process in a high resolution transmission electron microscope, the number of layers of the graphene nanoribbons, as well as the dimension of the carbon onions, can be controlled. It is found that the initial diameter of the nanofiber has a strong effect on the final results. A mechanism is proposed to explain the transformation of polymer nanofibers to carbon nanostructures under electron beam irradiation. This supposes that the polymer nanofibers are first carbonized and then graphitized as a result of the high energy electrons. According to the mechanism, it is believed that all polymer nanofibers could be carbonized and then converted to graphene nanoribbons by proper electron beam irradiation.

  1. Biofunctionalized nanofibers using Arthrospira (Spirulina) biomass and biopolymer.

    Science.gov (United States)

    de Morais, Michele Greque; Stillings, Christopher; Dersch, Roland; Rudisile, Markus; Pranke, Patrícia; Costa, Jorge Alberto Vieira; Wendorff, Joachim

    2015-01-01

    Electrospun nanofibers composed of polymers have been extensively researched because of their scientific and technical applications. Commercially available polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHB-HV) copolymers are good choices for such nanofibers. We used a highly integrated method, by adjusting the properties of the spinning solutions, where the cyanophyte Arthrospira (formally Spirulina) was the single source for nanofiber biofunctionalization. We investigated nanofibers using PHB extracted from Spirulina and the bacteria Cupriavidus necator and compared the nanofibers to those made from commercially available PHB and PHB-HV. Our study assessed nanofiber formation and their selected thermal, mechanical, and optical properties. We found that nanofibers produced from Spirulina PHB and biofunctionalized with Spirulina biomass exhibited properties which were equal to or better than nanofibers made with commercially available PHB or PHB-HV. Our methodology is highly promising for nanofiber production and biofunctionalization and can be used in many industrial and life science applications. PMID:25667931

  2. Random lasers based on organic epitaxial nanofibers

    International Nuclear Information System (INIS)

    We present a review on random lasing in organic nanofibers made of oligophenyl nanocrystals grown by molecular epitaxy on polar substrates. The nanofibers have sub-wavelength cross-sectional dimensions and can extend in length up to the millimeter scale. We report on random lasing properties of nanofibers, under subpicosecond photopumping, both in the coherent and incoherent regimes. With the aid of both optical and morphological studies on individual fibers, we get insight into one-dimensional coherent feedback taking place along the nanofibers' axes. Model calculations of light propagation in disordered media allow us to give a semiquantitative description of one-dimensional coherent random lasing near the lasing threshold. We also report on amplified simulated emission in individual nanofibers and demonstrate that nanoscale linear optical amplifiers can be obtained by molecular self-assembly at surfaces. Photophysical studies of nanofibers resorting to subpicosecond luminescence and pump–probe spectroscopy give us valuable information on temperature-dependent, excited-state nonlinear processes, such as exciton–exciton annihilation and photoinduced absorption. Excited-state effects strongly influence lasing thresholds under quasi-continuous-wave photoexcitation conditions, as demonstrated in photoexcitation experiments performed with nanosecond pulses. Last, we briefly discuss the potential of organic epitaxial nanofibers featuring low-threshold random lasing for photonic sensing applications. (review article)

  3. Occupational Exposure to Carbon Nanotubes and Nanofibers

    Science.gov (United States)

    ... These nanoscale-based products are typically called "first generation" products of nanotechnology. Many of these nanoscale-based ... TWA) concentration, and (4) describes strategies for controlling workplace exposures and implementing a medical surveillance program. The ...

  4. Gas Sensors Based on Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Nanofibers fabricated via electrospinning have specific surface approximately one to two orders of the magnitude larger than flat films, making them excellent candidates for potential applications in sensors. This review is an attempt to give an overview on gas sensors using electrospun nanofibers comprising polyelectrolytes, conducting polymer composites, and semiconductors based on various sensing techniques such as acoustic wave, resistive, photoelectric, and optical techniques. The results of sensing experiments indicate that the nanofiber-based sensors showed much higher sensitivity and quicker responses to target gases, compared with sensors based on flat films.

  5. Application of a biotin functionalized QD assay for determining available binding sites on electrospun nanofiber membrane

    Directory of Open Access Journals (Sweden)

    Magnone Joshua

    2011-10-01

    Full Text Available Abstract Background The quantification of surface groups attached to non-woven fibers is an important step in developing nanofiber biosensing detection technologies. A method utilizing biotin functionalized quantum dots (QDs 655 for quantitative analysis of available biotin binding sites within avidin immobilized on electrospun nanofiber membranes was developed. Results A method for quantifying nanofiber bound avidin using biotin functionalized QDs is presented. Avidin was covalently bound to electrospun fibrous polyvinyl chloride (PVC 1.8% COOH w/w containing 10% w/w carbon black membranes using primary amine reactive EDC-Sulfo NHS linkage chemistry. After a 12 h exposure of the avidin coated membranes to the biotin-QD complex, fluorescence intensity was measured and the total amount of attached QDs was determined from a standard curve of QD in solution (total fluorescence vs. femtomole of QD 655. Additionally, fluorescence confocal microscopy verified the labeling of avidin coated nanofibers with QDs. The developed method was tested against 2.4, 5.2, 7.3 and 13.7 mg spray weights of electrospun nanofiber mats. Of the spray weight samples tested, maximum fluorescence was measured for a weight of 7.3 mg, not at the highest weight of 13.7 mg. The data of total fluorescence from QDs bound to immobilized avidin on increasing weights of nanofiber membrane was best fit with a second order polynomial equation (R2 = .9973 while the standard curve of total fluorescence vs. femtomole QDs in solution had a linear response (R2 = .999. Conclusion A QD assay was developed in this study that provides a direct method for quantifying ligand attachment sites of avidin covalently bound to surfaces. The strong fluorescence signal that is a fundamental characteristic of QDs allows for the measurement of small changes in the amount of these particles in solution or attached to surfaces.

  6. Direct Fabrication of Enzyme-Carrying Polymer Nanofibers by Electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Herricks, Thurston E.; Kim, S. H.; Kim, Jungbae; Li, Dien; Kwak, Ja Hun; Grate, Jay W.; Kim, Samuel H.; Xia, Yuanxian

    2005-08-01

    Nanofibers of an enzyme-polymer composite were successfully electrospun with retained biocatalytic activity. The enzyme, ?-chymotrypsin, was solubilized in toluene via the aid of a surfactant and mixed with a polymer solution of polystyrene and poly(styrene-co-maleic anhydride). The enzyme-polymer solution could be directly electrospun to produce nanofibers with diameters of ~873 nm. The enzyme activity remained stable over the course of one week when nanofibers were treated with 0.1% glutaraldehyde solution. Untreated nanofibers rapidly lost the enzyme activity due to leaching of the enzyme from nanofibers. The nanofiber-based mats were durable and easily recovered from a solution.

  7. A hybrid biomimetic scaffold composed of electrospun polycaprolactone nanofibers and self-assembled peptide amphiphile nanofibers

    International Nuclear Information System (INIS)

    Nanofibrous electrospun poly (?-caprolactone) (ePCL) scaffolds have inherent structural advantages, but lack of bioactivity has limited their usefulness in biomedical applications. Thus, here we report the development of a hybrid, nanostructured, extracellular matrix (ECM) mimicking scaffold by a combination of ePCL nanofibers and self-assembled peptide amphiphile (PA) nanofibers. The PAs have ECM mimicking characteristics including a cell adhesive ligand (RGDS) and matrix metalloproteinase-2 (MMP-2) mediated degradable sites. Transmission electron microscope imaging verified successful PA self-assembly into nanofibers (diameters of 8-10 nm) using a solvent evaporation method. This evaporation method was then used to successfully coat PAs onto ePCL nanofibers (diameters of 300-400 nm), to develop hybrid, bioactive scaffolds. Scanning electron microscope characterization showed that the PA coatings did not interfere with the porous ePCL nanofiber network. Human mesenchymal stem cells (hMSCs) were seeded onto the hybrid scaffolds to evaluate their bioactivity. Significantly greater attachment and spreading of hMSCs were observed on ePCL nanofibers coated with PA-RGDS as compared to ePCL nanofibers coated with PA-S (no cell adhesive ligand) and uncoated ePCL nanofibers. Overall, this novel strategy presents a new solution to overcome the current bioactivity challenges of electrospun scaffolds and combines the unique characteristics of ePCL nanofibers and self-assembled cs of ePCL nanofibers and self-assembled PA nanofibers to provide an ECM mimicking environment. This has great potential to be applied to many different electrospun scaffolds for various biomedical applications

  8. Electrospun polyvinyl alcohol-honey nanofibers

    OpenAIRE

    Wang Ping; He Ji-Huan

    2013-01-01

    This paper sugeests a method for fabrication of polyvinyl alcohol-honey nanofibers by electrospinning. Polyvinyl alcohol and honey are all biocompatible and environmentally friendly materials. This combination will lead to wide potential applications in various engineering fields.

  9. Polysaccharide nanofiber made from euglenoid alga.

    Science.gov (United States)

    Shibakami, Motonari; Tsubouchi, Gen; Nakamura, Makoto; Hayashi, Masahiro

    2013-04-01

    We have fabricated a polysaccharide nanofiber made from paramylon (?-1,3-glucan), a storage polysaccharide stored as a micrometer-sized particle in the cell of euglenoid alga. Preparation of this nanofiber primarily hinges on the bottom-up approach. First, paramylon, which is originally present in the form of a bundle of nanofibers in a particle, was fibrillated to a randomly coiled polymer by dissolving the particle in a 1.0-mol/L NaOH aqueous solution. Second, the randomly coiled polymer was allowed to self-assemble into a triplex as the NaOH concentration was reduced to 0.25-0.20mol/L. Third, a 20-nm-width nanofiber made from the triplex emerged in the solution when the NaOH concentration was reduced to approximately 0.20mol/L. PMID:23499089

  10. CHARACTERISTIC OF NANOFIBERS EXTRACTED FROM KENAF CORE

    Directory of Open Access Journals (Sweden)

    Mehdi Joonobi

    2010-11-01

    Full Text Available Cellulose nanofibers were isolated from kenaf core fibers by employing chemo-mechanical treatments. The morphologies and sizes of the fibers were explored with environmental scanning electron microscopy (ESEM and transmission electron microscopy (TEM. The results of chemical analysis showed that the cellulose contents of the bleached pulp fibers and nanofibers increased from 46% to 92% and to 94%, respectively. Most of the produced nanofibers had diameters in the range of 20 to 25 nm, whereas kenaf nanofibers ranged in diameter diameters from 10 to 75 nm. Fourier transform infrared spectroscopy (FTIR analysis revealed the removal of lignin and the majority of the hemicelluloses from the kenaf core fibers. The thermogravimetric analysis (TGA, which was carried out to evaluate the thermal properties of the fibers, demonstrated that the thermal stabilities of these fibers were increased by the chemo-mechanical treatments. The results of X-ray analysis confirmed that chemical and mechanical treatments can improve the crystallinity of fibers.

  11. Collecting electrospun nanofibers with patterned electrodes.

    Science.gov (United States)

    Li, Dan; Ouyang, Gong; McCann, Jesse T; Xia, Younan

    2005-05-01

    Electrospinning is a simple, versatile, and useful technique for fabricating nanofibers from a rich variety of functional materials. The nanofibers are usually collected as nonwoven mats, in which the fibers are randomly oriented. We have recently demonstrated that the nanofibers can be uniaxially aligned by introducing an insulating gap into the conductive collector. To elucidate the mechanism of alignment, we have systematically studied the effect of the area and geometric shape of the insulating gap on the deposition of fibers. By modeling the electrostatic forces acting on the fiber, it was established that the fibers tended to be oriented along a direction such that the net torque of electrostatic forces applied to the two ends of a discrete segment of the fiber were minimized. By varying the design of electrode pattern, it was possible to control both alignment and assembly of the electrospun nanofibers. PMID:15884893

  12. Chemosensitizing effects of carbon-based nanomaterials in cancer cells: enhanced apoptosis and inhibition of proliferation as underlying mechanisms

    Science.gov (United States)

    Erdmann, Kati; Ringel, Jessica; Hampel, Silke; Rieger, Christiane; Huebner, Doreen; Wirth, Manfred P.; Fuessel, Susanne

    2014-10-01

    Recent studies have shown that carbon nanomaterials such as carbon nanofibres (CNFs) and multi-walled carbon nanotubes (CNTs) can exert antitumor activities themselves and sensitize cancer cells to conventional chemotherapeutics such as carboplatin and cisplatin. In the present study, the chemosensitizing effect of CNFs and CNTs on cancer cells of urological origin was investigated regarding the underlying mechanisms. Prostate cancer (DU-145, PC-3) and bladder cancer (EJ28) cells were treated with carbon nanomaterials (CNFs, CNTs) and chemotherapeutics (carboplatin, cisplatin) alone as well as in combination for 24 h. Forty-eight (EJ28) or 72 h (DU-145, PC-3) after the end of treatment the effects on cellular proliferation, clonogenic survival, cell death rate and cell cycle distribution were evaluated. Depending on the cell line, simultaneous administration of chemotherapeutics and carbon nanomaterials produced an additional inhibition of cellular proliferation and clonogenic survival of up to 77% and 98%, respectively, compared to the inhibitory effects of the chemotherapeutics alone. These strongly enhanced antiproliferative effects were accompanied by an elevated cell death rate, which was predominantly mediated via apoptosis and not by necrosis. The antitumor effects of combinations with CNTs were less pronounced than those with CNFs. The enhanced effects of the combinatory treatments on cellular function were mostly of additive to partly synergistic nature. Furthermore, cell cycle analysis demonstrated an arrest at the G2/M phase mediated by a monotreatment with chemotherapeutics. Following combinatory treatments, mostly less than or nearly additive increases of cell fractions in the G2/M phase could be observed. In conclusion, the pronounced chemosensitizing effects of CNFs and CNTs were mediated by an enhanced apoptosis and inhibition of proliferation. The combination of carbon-based nanomaterials and conventional chemotherapeutics represents a novel approach in cancer therapy to bypass chemoresistance by minimizing the chemotherapeutic dosing.

  13. Evaluation of the genotoxicity of cellulose nanofibers

    Directory of Open Access Journals (Sweden)

    de Lima R

    2012-07-01

    Full Text Available Renata de Lima,1 Leandro Oliveira Feitosa,1 Cintia Rodrigues Maruyama,1 Mariana Abreu Barga,1 Patrícia Cristina Yamawaki,1 Isolda Jesus Vieira,1 Eliangela M Teixeira,2 Ana Carolina Corrêa,2 Luiz Henrique Caparelli Mattoso,2 Leonardo Fernandes Fraceto31Department of Biotechnology, University of Sorocaba, Sorocaba, 2Embrapa Instrumentation (CNPDIA, National Nanotechnology Laboratory for Agriculture (LNNA, São Carlos, 3Department of Environmental Engineering, State University of São Paulo (UNESP, Sorocaba, SP, BrazilBackground: Agricultural products and by products provide the primary materials for a variety of technological applications in diverse industrial sectors. Agro-industrial wastes, such as cotton and curaua fibers, are used to prepare nanofibers for use in thermoplastic films, where they are combined with polymeric matrices, and in biomedical applications such as tissue engineering, amongst other applications. The development of products containing nanofibers offers a promising alternative for the use of agricultural products, adding value to the chains of production. However, the emergence of new nanotechnological products demands that their risks to human health and the environment be evaluated. This has resulted in the creation of the new area of nanotoxicology, which addresses the toxicological aspects of these materials.Purpose and methods: Contributing to these developments, the present work involved a genotoxicological study of different nanofibers, employing chromosomal aberration and comet assays, as well as cytogenetic and molecular analyses, to obtain preliminary information concerning nanofiber safety. The methodology consisted of exposure of Allium cepa roots, and animal cell cultures (lymphocytes and fibroblasts, to different types of nanofibers. Negative controls, without nanofibers present in the medium, were used for comparison.Results: The nanofibers induced different responses according to the cell type used. In plant cells, the most genotoxic nanofibers were those derived from green, white, and brown cotton, and curaua, while genotoxicity in animal cells was observed using nanofibers from brown cotton and curaua. An important finding was that ruby cotton nanofibers did not cause any significant DNA breaks in the cell types employed.Conclusion: This work demonstrates the feasibility of determining the genotoxic potential of nanofibers derived from plant cellulose to obtain information vital both for the future usage of these materials in agribusiness and for an understanding of their environmental impacts.Keywords: cotton, curaua, nanotoxicology, environmental nanotechnology

  14. Nanofibers and their applications in tissue engineering

    OpenAIRE

    Vasita, Rajesh; Katti, Dhirendra S.

    2006-01-01

    Developing scaffolds that mimic the architecture of tissue at the nanoscale is one of the major challenges in the field of tissue engineering. The development of nanofibers has greatly enhanced the scope for fabricating scaffolds that can potentially meet this challenge. Currently, there are three techniques available for the synthesis of nanofibers: electrospinning, self-assembly, and phase separation. Of these techniques, electrospinning is the most widely studied technique and has also dem...

  15. Selective nanofiber deposition via electrodynamic focusing

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Amani; Ziaie, Babak [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN (United States); Son, Chulwoo [School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN (United States)

    2008-09-17

    In this paper, we demonstrate the effect of electrodynamic focusing through a gold-coated PDMS shadow mask on the selective deposition of electrospun nanofibers. Under a suitable applied voltage, the PDMS mask repels the fibers from its surface while simultaneously forcing them into micron-sized holes and onto a collecting substrate. The presented technique is simple and can be used to produce lithographic-scale nanofiber deposition using a wide range of materials.

  16. Rotational dynamics of optically trapped polymeric nanofibers

    OpenAIRE

    Neves, Antonio Alvaro Ranha; Camposeo, Andrea; Pagliara, Stefano; Saija, Rosalba; Borghese, Ferdinando; Denti, Paolo; Iati, Maria Antonia; Cingolani, Roberto; Marago, Onofrio M.; Pisignano, Dario

    2009-01-01

    The optical trapping of polymeric nanofibers and the characterization of the rotational dynamics are reported. A strategy to apply a torque to a polymer nanofiber, by tilting the trapped fibers using a symmetrical linear polarized Gaussian beam is demonstrated. Rotation frequencies up to 10 Hz are measured, depending on the trapping power, the fiber length and the tilt angle. A comparison of the experimental rotation frequencies in the different trapping configurations with ...

  17. Selective nanofiber deposition via electrodynamic focusing

    International Nuclear Information System (INIS)

    In this paper, we demonstrate the effect of electrodynamic focusing through a gold-coated PDMS shadow mask on the selective deposition of electrospun nanofibers. Under a suitable applied voltage, the PDMS mask repels the fibers from its surface while simultaneously forcing them into micron-sized holes and onto a collecting substrate. The presented technique is simple and can be used to produce lithographic-scale nanofiber deposition using a wide range of materials

  18. Synthesis and Characterization of Boehmite Nanofibers

    Directory of Open Access Journals (Sweden)

    Ray L. Frost

    2008-10-01

    Full Text Available Boehmite nanofibers of high quality were synthesized through a wet-gel conversion process without the use of a surfactant. The long nanofibers of boehmite with clear-cut edges were obtained by steaming the wet-gel precipitate at 170∘C for 2 days. Analytical techniques such as X-ray diffraction (XRD, scanning electron microscopy (SEM, infrared emission spectroscopy (IES, as well as Raman spectroscopy were used to characterize the products.

  19. Characterization and application of electrospun alumina nanofibers

    OpenAIRE

    Kim, Jeon-hee; Yoo, Seung-joon; Kwak, Dong-heui; Jung, Heung-joe; Kim, Tae-young; Park, Kyung-hee; Lee, Jae-wook

    2014-01-01

    Alumina nanofibers were prepared by a technique that combined the sol–gel and electrospinning methods. The solution to be electrospun was prepared by mixing aluminum isopropoxide (AIP) in ethanol, which was then refluxed in the presence of an acid catalyst and polyvinylpyrolidone (PVP) in ethanol. The characterization results showed that alumina nanofibers with diameters in the range of 102 to 378 nm were successfully prepared. On the basis of the results of the XRD and FT-IR, the alumina ...

  20. Synthesis and Characterization of Boehmite Nanofibers

    OpenAIRE

    Jing Yang 2; Frost, Ray L.

    2008-01-01

    Boehmite nanofibers of high quality were synthesized through a wet-gel conversion process without the use of a surfactant. The long nanofibers of boehmite with clear-cut edges were obtained by steaming the wet-gel precipitate at 170?C for 2 days. Analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared emission spectroscopy (IES), as well as Raman spectroscopy were used to characterize the products.