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Sample records for carbon nanofibers cnfs

  1. Theoretical and practical aspects of chemical functionalization of carbon nanofibers (CNFs): DFT calculations and adsorption study.

    Rokhina, Ekaterina V; Lahtinen, Manu; Makarova, Katerina; Jegatheesan, Veeriah; Virkutyte, Jurate

    2012-06-01

    The nitric acid-functionalized commercial carbon nanofibers (CNFs) were comprehensively studied by instrumental (XRD, BET, SEM, TGA) and theoretical (DFT calculations) methods. The detailed surface study revealed the variation in the characteristics of functionalized CNFs, such as a decreased (up to 34%) surface area and impacted structural, electronic and chemical properties. The effects of functional groups were studied by comparison with pristine nanofibers. The results showed that the C-C bond lengths of the modified CNFs varied significantly. Chemical functionalization altered the frontier orbitals of the pristine material, and therefore altered the nature of their interactions with other substances. Moreover, the pristine and modified CNFs were tested for the removal of phenol from aqueous solutions. It was observed that surface modification tuned the adsorption capacity of carbon nanofibers (up to 0.35 mmol g(-1)), whereas original fibers did not demonstrate any adsorption capacity of phenol. PMID:22209137

  2. Microcellular foam injection molding with cellulose nanofibers (CNFs)

    Ohshima, Masahiro; Kubota, Masaya; Ishihara, Shota; Hikima, Yuta; Sato, Akihiro; Sekiguchi, Takafumi

    2016-03-01

    Cellulose nanofibers (CNFs) nanocomposites polypropylene foams are prepared by microcellular foam injection molding with core-back operation. The modified CNFs were blended with isotactic-polypropylene (i-PP) at different CNFs weight percentages and foamed to investigate the effect of CNFs on cell morphology. CNFs in i-PP increased the elastic modulus and induced a strain hardening behavior. CNFs also shifted the crystallization temperature of i-PP to higher temperature and enhanced crystallization. With these changes in rheological and thermal properties, CNFs could reduce the cell size and increase the cell density of the foams. By adjusting the core-back timing i.e., foaming temperature, the closed cell and the nano-fibrillated open cellular structure could be produced. The flexural modulus and bending strength of foams were measured by three point flexural tester. The flexural modulus and bending strength were increased as the CNFs content in i-PP was increased at any foam expansion ratio.

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

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

    2013-01-01

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

  4. A catechol biosensor based on electrospun carbon nanofibers

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

    2014-01-01

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

  5. Microstructure transformation of carbon nanofibers during graphitization

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

    2008-01-01

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

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

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

    2013-01-01

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

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

    Zhang, Wei; Kuhn, Luise Theil

    2013-01-01

    The article discusses the growth behavior of carbon nanofibers (CNFs). It mentions that CNFs can be synthesized using methods such as arc-discharge, laser ablation and chemical vapor deposition. It further states that CNFs can be grown from a physical mixing of amorphous carbon and CGO/Ni nanopar......The article discusses the growth behavior of carbon nanofibers (CNFs). It mentions that CNFs can be synthesized using methods such as arc-discharge, laser ablation and chemical vapor deposition. It further states that CNFs can be grown from a physical mixing of amorphous carbon and CGO....../Ni nanoparticles, devoid of any gaseous carbon source and external heating and stimulated by an electron beam in a 300 kilo volt transmission electron microscope....

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

    Jiapeng Fu

    2014-02-01

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

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

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

    2006-01-01

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

  10. The effect of embedded carbon nanotubes on the morphological evolution during the carbonization of poly(acrylonitrile) nanofibers

    Hybrid nanofibers with different concentrations of multi-walled carbon nanotubes (MWCNTs) in polyacrylonitrile (PAN) were fabricated using the electrospinning technique and subsequently carbonized. The morphology of the fabricated carbon nanofibers (CNFs) at different stages of the carbonization process was characterized by transmission electron microscopy and Raman spectroscopy. The polycrystalline nature of the CNFs was shown, with increasing content of ordered crystalline regions having enhanced orientation with increasing content of MWCNTs. The results indicate that embedded MWCNTs in the PAN nanofibers nucleate the growth of carbon crystals during PAN carbonization

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

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

    2015-01-01

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

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

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

    2016-01-01

    The catalysis and characterization of carbon nanofibers (CNFs) composite are reported in this work. Carbon nanofibers were produced on oil palm shell powdered activated carbon (PAC), which was impregnated with nickel. Chemical Vapor Deposition (CVD) of C2H2 was used in the presence of hydrogen at ∼650 °C. The flow rates of carbon source and hydrogen were fixed. The CNFs formed directly on the surface of the impregnated PAC. Variable weight percentages (1%, 3%, 5%, 7% and 9%) of the catalyst s...

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

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

    2013-01-01

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

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

    Takeshi Hikata

    2013-04-01

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

  15. Ultrasensitive electrospun nickel-doped carbon nanofibers electrode for sensing paracetamol and glucose

    The long, uniform and smooth Ni(NO3)2-loaded polyvinyl alcohol nanofibers were prepared via electrospinning on a nonconductive quartz plate. The nanofibers were stabilized at 300 °C for 3 h in nitrogen atmosphere, and then the continuous heating to 800 °C at the rate of 2 °C min−1 keeping 3 h was used to prepare nickel-doped carbon nanofibers (Ni:CNFs). The composites were characterized with Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The Ni:CNFs were used as the working electrode to sense paracetamol (PCT) and glucose (GLU), respectively. When sensing PCT, the Ni:CNFs electrode showed an electrochemical behavior like on macroelectrode; but for GLU, it displayed an electrochemical behavior like on microelectrode. For both of the species, higher sensitivities on the Ni:CNFs electrodes were obtained than those on bulk glassy carbon and nickel electrodes

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

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

    2015-11-01

    In this study, carbon nanofibers (CNFs) were grown by chemical vapor deposition on C-fiber textiles that had Ni and Cu catalyst deposited via electrophoretic deposition. Before the CNFs were coated with silica layer via hydrolysis of TEOS (Tetraethyl orthosilicate), the carbon nanofibers were oxidized by nitric acid. Due to oxidation, the hydroxyl group was created on the carbon nanofibers and this was used as an activation site for the SiO2. The physicochemical properties of the grown carbon nanofibers were investigated with Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The structures of SiO2-coated carbon nanofibers were characterized by XPS and TEM. The electrochemical properties and the capacitance of the materials were investigated by galvanostatic charge-discharge and cyclic voltammetry. Different types of carbon nanofibers were grown upon the deposition utilizing catalysts, with the SiO2 uniformly coated on the surface of carbon nanofibers. When used as an anode material for the Li secondary battery, the SiO2/CNFs composite had a lower capacity maintenance and a greater discharge capacity as compared to the carbon nanofibers. PMID:26726630

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

    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.

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

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

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

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

    2015-03-01

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

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

    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.

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

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

    2014-01-01

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

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

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

    2014-05-01

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

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

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

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

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

    2016-03-01

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

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

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

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

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

    2015-08-28

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

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

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

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

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

    2015-08-01

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

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

    Xueping Zhang; Dong Liu; Libo Li; Tianyan You

    2015-01-01

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

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

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

    2016-09-01

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

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

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

    2016-05-01

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

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

    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)

  13. Carbon nanofiber supercapacitors with large areal capacitances

    McDonough, James R.

    2009-01-01

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

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

    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

  15. Direct production of carbon nanofibers decorated with Cu2O by thermal chemical vapor deposition on Ni catalyst electroplated on a copper substrate

    MA Vesaghi

    2012-12-01

    Full Text Available  Carbon nanofibers (CNFs decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal. chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 35˚C. These nanoparticles provide the nucleation sites for CNF growth, removing the need for a buffer layer. High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at atmospheric environment, during the CNFs growth, lead to the production of CNFs decorated with Cu2O particles. The surface morphology of the Ni catalyst films and grown CNFs over it was studied by scanning electron microscopy. Transmission electron microscopy and Raman spectroscopy revealed the formation of CNFs. The selected area electron diffraction pattern and electron diffraction studies show that these CNFs were decorated with Cu2O nanoparticles.

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

    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

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

    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. (paper)

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

    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.

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

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

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

  20. Processing and Structure of Carbon Nanofiber Paper

    Zhongfu Zhao

    2009-01-01

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

  1. Adsorption behavior of perfluorinated sulfonic acid ionomer on highly graphitized carbon nanofibers and their thermal stabilities

    Andersen, Shuang Ma; Borghei, Maryam; Dhiman, Rajnish;

    2014-01-01

    A systematic adsorption study of perfluorinated sulfonic acid Nafion® ionomer on ribbon type highly graphitized carbon nanofibers (CNFs) was carried out using 19 fluorine nuclear magnetic resonance spectroscopy. Based on the values obtained for the equilibrium constant (Keq., derived from Langmui...... coverage (ΓSmax) of the CNFs is one order of magnitude higher than the one of Vulcan. The large discrepancy is due to the fact that the ionomers are inaccessible to the internal surface area of Vulcan with high micro porosity....

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

    S. K. Nataraj

    2013-01-01

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

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

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

    2015-10-01

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

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

    Asiri AM

    2014-12-01

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

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

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

    2016-08-15

    Controllable synthesis of carbon nanofibers (CNFs) with hierarchical porosity and high flexibility are extremely desirable for CO2 adsorption and energy storage applications. Herein, we report a nickel cobaltite/carbon nanotubes doped CNFs (NiCo2O4/CNTs CNFs) mesoporous membrane that shows well-developed flexibility, tailored pore structure, hydrophobic character, and high stability. Ascribed to these unique features, NiCo2O4/CNTs CNFs membrane shows high CO2 capture of 1.54mmol/g at 25°C and 1.0bar, and electrochemical measurements for supercapacitors exhibit good performance with specific capacitances of 220F/g (in 1M KOH) at a current density of 1A/g. The successful synthesis of such hybrid membrane provides new insight into development of various multifunctional applications. PMID:27209394

  6. Magnetic properties of NiFe{sub 2}O{sub 4}/carbon nanofibers from Venezuelan petcoke

    Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cañizales, Edgard [Área de Análisis Químico Inorgánico, PDVSA, INTEVEP, Los Teques 1070-A (Venezuela, Bolivarian Republic of)

    2015-05-01

    NiFe{sub 2}O{sub 4}/carbon nanofibers (NiFe{sub 2}O{sub 4}/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe{sub 2}O{sub 4} as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe{sub 2}O{sub 4}/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs. - Highlights: • NiFe{sub 2}O{sub 4}/CNFs have been synthesized by hydrothermal method using petroleum coke. • Nickel ferrite nanoparticles were used as the catalyst. • HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. • The size of the nanoparticles defines the diameter of the CNFs.

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

    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

  8. Ti-doped SnOx encapsulated in Carbon nanofibers with enhanced lithium storage properties

    Hybrid nanocomposites composed of carbon nanofibers and Ti-doped SnOx nanoparticles with varied molar ratios of Ti/Sn (=0.05, 0.1 and 0.2) have been prepared through electrospinning technique and subsequent thermal treatments. High-resolution transmission electron microscopy showed that the Ti-doped SnOx nanoparticles with a very small particle size of 2∼4 nm were uniformly encapsulated in the carbon nanofibers (CNFs). Among the as-prepared samples, the electrode with the Ti/Sn molar ratio of 0.1 delivered the best reversible capacity of 670.7 mAh g−1 at the 60th cycle, which was 17.9% higher than that of the pristine SnOx/CNFs (SOC). What is more, the optimal electrode presented good rate performance (302.1 mAh g−1 at 2 A g−1). The enhanced lithium storage properties of Ti-doped SnOx/CNFs (TSOC) can be attributed to the uniform encapsulation of ultrafine SnOx nanoparticles in the conductive CNFs as well as the doping with Ti4+

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

    Platelet graphite nanofibers (PGNFs) and turbostratic carbon nanofibers (TSCNFs) were synthesized by the pyrolysis of 3 and 10 vol% chloroform in ethanol, respectively, in the presence of Ni catalyst at 700 °C. Auger electron spectrometry analysis reveals that the participation of chloroform in the synthesis led to Ni–Cl bonding on the surface of the catalysts, resulting in a relatively poor crystalline layer and a coarse surface. Furthermore, the Ni–Cl compound affected the melting point and mobility of Ni, changing the morphology and geometrical shape of Ni particles. A low amount of chlorine in the catalyst led to the formation of smaller catalyst particles with a flat surface, resulting in graphene nanosheets stacked perpendicular to the fiber axis, which became PGNFs. In contrast, a high amount of chlorine in the catalyst led to the aggregation of the catalyst and thus the formation of large catalyst particles with a rough surface, resulting in the random stacking of graphene nanosheets, which became TSCNFs. The participation of chlorine was found to be important in the synthesis of the PGNFs and TSCNFs. - Graphical abstract: Display Omitted - Highlights: • The morphology of CNFs changed while different amount of CHCl3 presented. • The interaction of Ni and Cl changed the geometry and morphology of catalysts. • The structure of CNFs formed attributed to the surface morphology of catalysts. • PGNFs and TSCNFs were perpendicular and random stacking of graphene

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

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

    2015-08-01

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

  11. Silicon Whisker and Carbon Nanofiber Composite Anode

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

    2015-01-01

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

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

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

    2016-04-01

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

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

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

    2016-06-01

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

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

    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

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

    A.A. Mamun

    2016-07-01

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

  16. Effect of carbon nanofibers on the infiltration and thermal conductivity of carbon/carbon composites

    Highlights: → The CNFs improve the infiltration rate and thermal properties of carbon/carbon composites. → The densification rate increases with the CNF content increasing at the beginning of infiltration. → The values of the thermal conductivity of the composite obtain their maximum values at 5 wt.%. -- Abstract: Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated using the electrified preform heating chemical vapor infiltration method (ECVI) under atmospheric pressure. Initial thermal gradients were determined. Resistivity and density evolutions with infiltration time have been recorded. Scanning electron microscopy, polarized light micrograph and X-ray diffraction technique were used to analyze the experiment results. The results showed that the infiltration rate increased with the rising of CNF content, and after 120 h of infiltration, the density was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 wt.% to 20 wt.%. CNF-reinforced C/C composites have enhanced thermal conductivity, the values at 5 wt.% were increased by nearly 5.5-24.1% in the X-Y direction and 153.8-251.3% in the Z direction compared to those with no CNFs. When the additive content was increased to 20 wt.%, due to the holes and cavities in the CNF web and between carbon cloth and matrix, the thermal conductivities in the X-Y and Z directions decreased from their maximum values at 5 wt.%.

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

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

    2013-01-01

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

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

    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), Hα (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 γ-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 less than 5 min. Alignment deteriorates as CNFs grow and deposition was virtually terminated by the deactivation of catalyst particles

  19. Fabrication of a novel visible-light-driven photocatalyst Ag-AgI-TiO{sub 2} nanoparticles supported on carbon nanofibers

    Yu, Dandan; Bai, Jie, E-mail: baijie@imut.edu.cn; Liang, Haiou; Wang, Junzhong; Li, Chunping

    2015-09-15

    Graphical abstract: - Highlights: • Visible-light-induced Ag-AgI-TiO{sub 2}/CNFs nanocomposites had been successfully prepared. • Ag-AgI-TiO{sub 2}/CNFs could be easily separated and recycled from an aqueous solution. • The application of CNFs acting as supporters made the photocatalysts have high adsorption capacity. • Ag-AgI-TiO{sub 2}/CNFs could efficiently degrade different organic dyes. - Abstract: Novel visible-light-driven photocatalysts Ag-AgI-TiO{sub 2} nanoparticles embedded onto carbon nanofibers were successfully prepared. Electrospinning technology followed by high-temperature calcination was adopted for the fabrication of carbon nanofibers (CNFs) acting as a supporter. Ag-TiO{sub 2}/CNFs nanocomposites were prepared by combining in situ reduction with physical adsorption process. Ag-AgI-TiO{sub 2}/CNFs were synthesized by oxidizing some silver nanoparticles (Ag NPs) contained in Ag-TiO{sub 2}/CNFs to silver iodine (AgI) via chemical oxidation method using iodine (I{sub 2}) as oxidation agents. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), and Fourier transform infrared spectroscopy (FTIR). The as-fabricated Ag-AgI-TiO{sub 2}/CNFs showed high efficient adsorption and photocatalytic activity for decomposition of methyl orange (MO), acid red 18 (AR18), methylene blue (MB), and fluorescence sodium under visible light irradiation, which were attributed to the synergistic effects between the high adsorption capacity, good conductivity of carbon nanofibers, and the extraordinary plasma effect of Ag-AgI nanoparticles. In addition, the as-prepared composites could be easily separated from the solution phase due to the large length–diameter ratio of CNFs. The mechanism for the enhanced photocatalytic activity concerned with Ag-AgI-TiO{sub 2}/CNFs was proposed.

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

    Li-hua TENG; Tian-di TANG

    2008-01-01

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

  1. Highly Flexible Freestanding Porous Carbon Nanofibers for Electrodes Materials of High-Performance All-Carbon Supercapacitors.

    Liu, Ying; Zhou, Jinyuan; Chen, Lulu; Zhang, Peng; Fu, Wenbin; Zhao, Hao; Ma, Yufang; Pan, Xiaojun; Zhang, Zhenxing; Han, Weihua; Xie, Erqing

    2015-10-28

    Highly flexible porous carbon nanofibers (P-CNFs) were fabricated by electrospining technique combining with metal ion-assistant acid corrosion process. The resultant fibers display high conductivity and outstanding mechanical flexibility, whereas little change in their resistance can be observed under repeatedly bending, even to 180°. Further results indicate that the improved flexibility of P-CNFs can be due to the high graphitization degree caused by Co ions. In view of electrode materials for high-performance supercapacitors, this type of porous nanostructure and high graphitization degree could synergistically facilitate the electrolyte ion diffusion and electron transportation. In the three electrodes testing system, the resultant P-CNFs electrodes can exhibit a specific capacitance of 104.5 F g(-1) (0.2 A g(-1)), high rate capability (remain 56.5% at 10 A g(-1)), and capacitance retention of ∼94% after 2000 cycles. Furthermore, the assembled symmetric supercapacitors showed a high flexibility and can deliver an energy density of 3.22 Wh kg(-1) at power density of 600 W kg(-1). This work might open a way to improve the mechanical properties of carbon fibers and suggests that this type of freestanding P-CNFs be used as effective electrode materials for flexible all-carbon supercapacitors. PMID:26449440

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

    Dawei Li

    2015-11-01

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

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

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

    2016-01-20

    We present a method to produce composite anodes consisting of thermally reduced graphene oxide-containing carbon nanofibers (TRGO/CNFs) via electrospinning a dispersion of polyacrylonitrile (PAN) and graphene oxide (GO) sheets in dimethylformamide followed by heat treatment at 650 °C. A range of GO (1-20 wt % GO relative to polymer concentration) was added to the polymer solution, with each sample comprising similar polymer chain packing and subsequent CNF microstructure, as assessed by X-ray diffraction. An increase from 0 to 20 wt % GO in the fibers led to carbonized nonwovens with enhanced electronic conductivity, as TRGO sheets conductively connected the CNFs. Galvanostatic half-cell cycling revealed that TRGO addition enhanced the specific discharge capacity of the fibers. The optimal GO concentration of 5 wt % GO enhanced first-cycle discharge capacities at C/24 rates (15.6 mA g(-1)) 150% compared to CNFs, with a 400% capacity increase at 2-C rates (750 mA g(-1)). We attribute the capacity enhancement to a high degree of GO exfoliation. The TRGO/CNFs also experienced no capacity fade after 200 cycles at 2-C rates. Impedance spectroscopy of the composite anodes demonstrated that charge-transfer resistances decreased as GO content increased, implying that high GO loadings result in more electrochemically active material. PMID:26704705

  4. Free-standing nitrogen-doped carbon nanotubes at electrospun carbon nanofibers composite as an efficient electrocatalyst for oxygen reduction

    Efficient and non-Pt catalysts are highly desirable for many kinds of electrochemical applications. Herein, we have investigated the free-standing nitrogen-doped carbon nanotubes/carbon nanofibers composite (NCNT/CNFs) as an efficient cathode catalyst for the oxygen reduction reaction (ORR). The composite with a hierarchical structure is prepared by the pyrolysis of pyridine over flexible electrospun carbon nanofibers film (CNFs) supported with the nano-Fe catalyst. Scanning electron microscopy and transmission electron microscopy characterizations indicated that the curved NCNTs are sparsely, but tightly distributed on CNF surface. The as-prepared composite displayed good catalytic activity for ORR in an alkaline medium, with a favorable four-electron pathway, better long-term stability (94.6% retention after 10000 s), selectivity and resistance to the methanol crossover compared to the powder-form NCNTs and commercial Pt/C catalyst. The improved electrochemical performance of the NCNT/CNFs can be mainly attributed to the pyridinic-N doping and unique three-dimensional network structure. The results indicate that this novel composite can be used as a promising Pt-free ORR electrocatalyst

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

    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

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

    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.

  7. Anchoring Fe3O4 nanoparticles on three-dimensional carbon nanofibers toward flexible high-performance anodes for lithium-ion batteries

    Wan, Yizao; Yang, Zhiwei; Xiong, Guangyao; Guo, Ruisong; Liu, Ze; Luo, Honglin

    2015-10-01

    There is growing interest in flexible, cost-effective, and binder-free energy storage devices to meet the special needs of modern electronic systems. Herein we report a general, scalable, eco-friendly, and cost-effective approach for the fabrication of nano-Fe3O4-anchored three-dimensional (3D) carbon nanofiber (CNFs) aerogels (Fe3O4@BC-CNFs). The preparation processes include the anchoring of Fe2O3 nanoparticles on bacterial cellulose (BC) nanofibers with intrinsic 3D network structure and subsequent carbonization at different temperatures. The aerogel carbonized at 600 °C (Fe3O4@BC-CNFs-600) is highly flexible and was directly used as working electrodes in lithium-ion batteries without metal current collectors, conducting additives, or binders. The Fe3O4@BC-CNFs-600 demonstrates greatly improved electrochemical performance in comparison to the bare Fe3O4 nanoparticles. In addition to its excellent flexibility, a stable capacity of 755 mAh g-1 for up to 80 cycles is also higher than most of carbon-Fe3O4 hybrids. The high reversible capacity and excellent rate capability are attributed to its 3D porous network structure with well-dispersed Fe3O4 nanoparticles on the surfaces of CNFs.

  8. Effects of Thickness and Amount of Carbon Nanofiber Coated Carbon Fiber on Improving the Mechanical Properties of Nanocomposites

    Ferial Ghaemi

    2016-01-01

    Full Text Available In the current study, carbon nanofibers (CNFs were grown on a carbon fiber (CF surface by using the chemical vapor deposition method (CVD and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP composite were investigated. To obtain an optimum surface area, thickness, and yield of the CNFs, the parameters of the chemical vapor deposition (CVD method, such as catalyst concentration, reaction temperature, reaction time, and hydrocarbon flow rate, were optimized. It was observed that the optimal surface area, thickness, and yield of the CNFs caused more adhesion of the fibers with the PP matrix, which enhanced the composite properties. Besides this, the effectiveness of reinforcement of fillers was fitted with a mathematical model obtaining good agreement between the experimental result and the theoretical prediction. By applying scanning electronic microscope (SEM, transmission electron microscope (TEM, and Raman spectroscopy, the surface morphology and structural information of the resultant CF-CNF were analyzed. Additionally, SEM images and a mechanical test of the composite with a proper layer of CNFs on the CF revealed not only a compactness effect but also the thickness and surface area roles of the CNF layers in improving the mechanical properties of the composites.

  9. Structure and electrochemical applications of boron-doped graphitized carbon nanofibers

    Yeo, Jae-Seong; Jang, Sang-Min; Miyawaki, Jin; An, Bai; Mochida, Isao; Rhee, Choong Kyun; Yoon, Seong-Ho

    2012-08-01

    Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d002) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d002 is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d002 between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d002 to 3.356 Å. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338 mAh g-1 between 0 and 0.5 V versus Li/Li+ and 368 mAh g-1 between 0 and 1.5 V versus Li/Li+. The first-cycle Coulombic efficiency was also enhanced to 71-80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C.

  10. Structure and electrochemical applications of boron-doped graphitized carbon nanofibers

    Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d002) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d002 is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d002 between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d002 to 3.356 Å. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338 mAh g−1 between 0 and 0.5 V versus Li/Li+ and 368 mAh g−1 between 0 and 1.5 V versus Li/Li+. The first-cycle Coulombic efficiency was also enhanced to 71–80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C. (paper)

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

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

    2006-01-01

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

  12. Characteristics and Electrochemical Performance of Si-Carbon Nanofibers Composite as Anode Material for Binder-Free Lithium Secondary Batteries.

    Hyun, Yura; Park, Heai-Ku; Park, Ho-Seon; Lee, Chang-Seop

    2015-11-01

    The carbon nanofibers (CNFs) and Si-CNFs composite were synthesized using a chemical vapor deposition (CVD) method with an iron-copper catalyst and silicon-covered Ni foam. Acetylene as a carbon source was flowed into the quartz reactor of a tubular furnace heated to 600 degrees C. This temperature was maintained for 10 min to synthesize the CNFs. The morphologies, compositions, and crystal quality of the prepared CNFs were characterized by Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the Si-CNFs composite as an anode of the Li secondary batteries were investigated using a three-electrode cell. The as-deposited Si-CNF composite on the Ni foam was directly employed as an working electrode without any binder, and lithium foil was used as the counter and reference electrode. A glass fiber separator was used as the separator membrane. Two kinds of electrolytes were employed; 1) 1 M LiPF6 was dissolved in a mixture of EC (ethylene carbonate): PC (propylene carbonate): EMC (Ethyl methyl carbonate) in a 1:1:1 volume ratio and 2) 1 M LiClO4 was dissolved in a mixture of propylene carbonate (PC): ethylene carbonate (EC) in a 1:1 volume ratio. The galvanostatic charge-discharge cycling and cyclic voltammetry measurements were carried out at room temperature by using a battery tester. The resulting Si-CNFs composite achieved the large discharge capacity of 613 mAh/g and much improved cycle-ability with the retention rate of 87% after 20 cycles. PMID:26726625

  13. In{sub 2}S{sub 3}/carbon nanofibers/Au ternary synergetic system: Hierarchical assembly and enhanced visible-light photocatalytic activity

    Zhang, Xin; Shao, Changlu, E-mail: clshao@nenu.edu.cn; Li, Xinghua, E-mail: lixh781@nenu.edu.cn; Lu, Na; Wang, Kexin; Miao, Fujun; Liu, Yichun

    2015-02-11

    Graphical abstract: We describe a route to synthesize In{sub 2}S{sub 3}/CNFs/Au ternary synergetic system with high efficiency visible-light photocatalytic activity. - Highlights: • Synthesis of In{sub 2}S{sub 3}/CNFs/Au ternary synergetic system. • Enhanced visible-light photocatalytic activity. • Easy photocatalyst separation and reuse. - Abstract: 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 In{sub 2}S{sub 3}/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 In{sub 2}S{sub 3} nanosheets with 5–10 nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In{sub 2}S{sub 3}/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In{sub 2}S{sub 3} and In{sub 2}S{sub 3}/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron–hole pairs based on the positive synergetic effect between In{sub 2}S{sub 3}, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In{sub 2}S{sub 3}/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 In{sub 2}S{sub 3}/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure.

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

    Liu Tian

    2011-01-01

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

  15. Optical limiting of high-repetition-rate laser pulses by carbon nanofibers suspended in polydimethylsiloxane

    Videnichev, Dmitry A.; Belousova, Inna M.

    2014-06-01

    The optical limiting (OL) behavior of carbon nanofibers (CNFs) in polydimethylsiloxane (PDMS) was studied and compared with that of CNFs in water, and polyhedral multi-shell fullerene-like nanostructures (PMFNs) also in water. It was shown that when switching from single-shot to pulse-periodic regime of laser pulses (10 Hz), the CNF in PDMS suspension retains its OL characteristics, while in the aqueous suspensions, considerable degradation of OL characteristics is observed. It was also observed that a powerful laser pulse causes the CNF in PDMS suspension to become opaque for at least three seconds, while such a pulse brings out a bleaching effect in aqueous PMFN and CNF suspensions. The processes of OL degradation in aqueous suspensions, bleaching and darkening of the studied materials are discussed herein.

  16. Nondestructive evaluation of ±45° flat-braided carbon-fiber-reinforced polymers with carbon nanofibers using HTS-SQUID gradiometer

    Hatsukade, Y., E-mail: hatukade@ens.tut.ac.jp [Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Shinyama, Y.; Yoshida, K. [Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Takai, Y. [Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Aly-Hassan, M.S.; Nakai, A.; Hamada, H. [Advanced Fibro-Science Division, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Adachi, S.; Tanabe, K. [International Superconductivity Technology Center, Superconductivity Research Laboratory, 10-13, Shinonome 1-chome, Koto-ku, Tokyo 135-0062 (Japan); Tanaka, S. [Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

    2013-01-15

    Highlights: ► Tensile load was applied to braided CFRPs with and without CNFs and cutting edges. ► Visualization method using SQUID gradiometer was also applied to the braided CFRPs. ► Different destructive mechanisms and current distributions were obtained. ► Dispersed CNFs enhanced mechanical and electrical properties of the braided CFRPs. -- Abstract: Step-by-step tensile tests were applied to flat-braided carbon-fiber-reinforced polymers with and without added dispersions of carbon nanofibers (CNFs) and with and without sample sides cut off to study their mechanical properties and destructive mechanisms by means of in situ observation and stress–strain measurements. An ex situ nondestructive evaluation technique, using a high-temperature superconductor superconducting quantum interference device gradiometer, was also applied to the samples to study their electrical properties; the relationships between the mechanical and electrical properties by visualizing current maps in the samples during ac current injection was also studied. Clear differences were observed in the mechanical and electrical properties and the destructive mechanisms between the samples with and without CNFs and with and without cut off sides. These differences were mainly attributed to the addition of CNFs, which enhanced the mechanical and electrical connections between the carbon fiber bundles.

  17. Nondestructive evaluation of ±45° flat-braided carbon-fiber-reinforced polymers with carbon nanofibers using HTS-SQUID gradiometer

    Highlights: ► Tensile load was applied to braided CFRPs with and without CNFs and cutting edges. ► Visualization method using SQUID gradiometer was also applied to the braided CFRPs. ► Different destructive mechanisms and current distributions were obtained. ► Dispersed CNFs enhanced mechanical and electrical properties of the braided CFRPs. -- Abstract: Step-by-step tensile tests were applied to flat-braided carbon-fiber-reinforced polymers with and without added dispersions of carbon nanofibers (CNFs) and with and without sample sides cut off to study their mechanical properties and destructive mechanisms by means of in situ observation and stress–strain measurements. An ex situ nondestructive evaluation technique, using a high-temperature superconductor superconducting quantum interference device gradiometer, was also applied to the samples to study their electrical properties; the relationships between the mechanical and electrical properties by visualizing current maps in the samples during ac current injection was also studied. Clear differences were observed in the mechanical and electrical properties and the destructive mechanisms between the samples with and without CNFs and with and without cut off sides. These differences were mainly attributed to the addition of CNFs, which enhanced the mechanical and electrical connections between the carbon fiber bundles

  18. Preparation and characterization of carbon nanofiber-polymide composites

    Li, Xiaobing

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

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

    Cheng Jin

    2008-01-01

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

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

    Cheng Jin; Zou Xiaoping; Zhang Hongdan; Li Fei; Ren Pengfei; Zhu Guang; Su Yi; Wang Maofa

    2008-01-01

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

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

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

    2016-04-21

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

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

    Basaldua, Daniel Thomas

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

  3. Carbon nanofibers with radially grown graphene sheets derived from electrospinning for aqueous supercapacitors with high working voltage and energy density

    Zhao, Lei; Qiu, Yejun; Yu, Jie; Deng, Xianyu; Dai, Chenglong; Bai, Xuedong

    2013-05-01

    Improvement of energy density is an urgent task for developing advanced supercapacitors. In this paper, aqueous supercapacitors with high voltage of 1.8 V and energy density of 29.1 W h kg-1 were fabricated based on carbon nanofibers (CNFs) and Na2SO4 electrolyte. The CNFs with radially grown graphene sheets (GSs) and small average diameter down to 11 nm were prepared by electrospinning and carbonization in NH3. The radially grown GSs contain between 1 and a few atomic layers with their edges exposed on the surface. The CNFs are doped with nitrogen and oxygen with different concentrations depending on the carbonizing temperature. The supercapacitors exhibit excellent cycling performance with the capacity retention over 93.7% after 5000 charging-discharging cycles. The unique structure, possessing radially grown GSs, small diameter, and heteroatom doping of the CNFs, and application of neutral electrolyte account for the high voltage and energy density of the present supercapacitors. The present supercapacitors are of high promise for practical application due to the high energy density and the advantages of neutral electrolyte including low cost, safety, low corrosivity, and convenient assembly in air.

  4. Electrospun Ni-added SnO2-carbon nanofiber composite anode for high-performance lithium-ion batteries.

    Kim, Dongha; Lee, Daehee; Kim, Joosun; Moon, Jooho

    2012-10-24

    The SnO(2) anode is a promising anode for next-generation Li ion batteries because of its high theoretical capacity. However, it exhibits inherent capacity fading because of the large volume change and pulverization that occur during the charge/discharge cycles. The buffer matrix, such as electrospun carbon nanofibers (CNFs), can alleviate this problem to some extent, but SnO(2) particles are thermodynamically incompatible with the carbon matrix such that large Sn agglomerates form after carbonization upon melting of the Sn. Herein, we introduce well-dispersed nanosized SnO(2) attached to CNFs for high-performance anodes developed by Ni presence. The addition of Ni increases the stability of the SnO(2) such that the morphologies of the dispersed SnO(2) phase are modified as a function of the Ni composition. The optimal adding composition is determined to be Ni:Sn = 10:90 wt % in terms of the crystallite size and the distribution uniformity. A high capacity retention of 447.6 mA h g(-1) after 100 cycles can be obtained for 10 wt % Ni-added SnO(2)-CNFs, whereas Ni-free Sn/SnO(2)-CNFs have a capacity retention of 304.6 mA h g(-1). PMID:22999049

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

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

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

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

    2014-01-01

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

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

    Shuai, Danmeng

    2012-03-06

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

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

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

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

    Aboueloyoun Taha, Ahmed

    2015-12-01

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

  10. Electrospun Carbon Nanotube-Reinforced Nanofiber.

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

    2016-03-01

    We fabricated multi-walled carbon nanotube (MWNT) reinforced polyurethane (PU) nanofiber (MWNT-PU) web via electrospinning. In order to optimize the electrospinning conditions, we investigated the effects of various parameters including kind of solvent, viscosity of the spinning solution, and flow rate on the spinnability and properties of nanofiber. N,N-dimethylformamide (DMF), tetrahydrofuran (THF) and their mixture with various volume ratio were used as the spinning solvent. Morphology of the nanofiber was studied using scanning electron microscope (SEM) and transmission electron microscope (TEM), confirming successful fabrication of MWNT-PU nanofiber web with uniform dispersion of MWNT in longitudinal direction of the fiber. The MWNT-PU nanofiber web exhibited two times higher tensile strength than PU nanofiber web. We also fabricated electrically conducting MWNT-PU nanofiber web by coating poly(3,4-ehtylenedioxythiophene) (PEDOT) on the surface of MWNT-PU nanofiber web for electromagnetic interference (EMI) shielding application. The electromagnetic interference shielding effectiveness (EMI SE) was quite high as 25 dB in the frequency range from 50 MHz to 10 GHz. PMID:27455732

  11. Controlled morphology evolution of electrospun carbon nanofiber templated tungsten disulfide nanostructures

    Three-dimensional (3D) WS2-nanoflower decorated and two-dimensional (2D) WS2-nanosheet (NS) wrapped carbon nanofiber (CNF) nanostructures are constructed through a simple approach using (NH4)2WS4 contained electrospun polyacrylonitrile nanofibers (W-PAN NFs) and S powder as the precursor. (NH4)2WS4 are thermally decomposed into WS2 nanoparticles (NPs) during a pre-oxidation treatment of W-PAN NFs. Interestingly, the introducing of S vapor during the carbonization of W-PAN NFs results in unexpected migration of WS2 nanoparticles (WS2 NPs) from the inside of CNFs to the surface to form WS2 NSs or WS2 nanoflowers. It is believed that S not only controls the initial nucleation of WS2 on the surface of CNFs but also induces the migration of WS2 NPs and directs the growth of WS2 into various morphologies. The synthesized catalysts are directly used as the electrode for hydrogen evolution reaction (HER) and they exhibit good electrocatalytic activity

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

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

    2012-01-01

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

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

    A. M. Gumel

    2014-01-01

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

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

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

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

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

    2012-02-01

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

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

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

    2015-05-01

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

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

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

    2014-12-05

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

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

    Highlights: • Graphene-CNF-alloy nanoparticle hybrid nanostructure fabricated using CVD. • The hybrid consists of highly crystalline graphene, alloy nanoparticles and CNFs. • The hybrid carbon nanomaterial exhibits interesting induced magnetism. - Abstract: Graphene-carbon nanofiber (CNF) hybrid materials were synthesized by a simple one-step chemical vapour deposition method using propane over a Co63Ni37 alloy catalyst supported on a silicon substrate at 800 °C. The process involves catalyst de-wetting, carbon diffusion and precipitation, with the additional carbon being provided by the polymer (photo-resist, HPR-504). The formation of a graphene-CNF hybrid structure was observed in the presence of the polymer. The polymer plays a crucial role in the formation of the flat carbon nanostructures. In the absence of the polymer, only carbon nanotube growth was observed with the same catalyst under identical experimental conditions. The effect of the polymeric photo-resist layer on the growth of the hybrid structure was analyzed. Structural and morphological data in combination with the Raman spectroscopic data confirmed the formation of a few layers of highly crystalline graphene and CNFs in a hybrid structure. The magnetic behaviour of these as-grown graphene-CNF hybrid samples has been analyzed by using a superconducting quantum interference device (SQUID). The results from the magnetic measurements on these samples have also been discussed

  19. Using Converter Dust to Produce Low Cost Cementitious Composites by in situ Carbon Nanotube and Nanofiber Synthesis

    Péter Ludvig

    2011-03-01

    Full Text Available Carbon nanotubes (CNTs and nanofibers (CNFs were synthesized on clinker and silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an in situ chemical vapor deposition (CVD process using converter dust, an industrial byproduct, as iron precursor. The use of these materials reduces the cost, with the objective of application in large-scale nanostructured cement production. The resulting products were analyzed by scanning electron microscopy (SEM, transmission electron microscopy (TEM and thermogravimetric analysis (TGA and were found to be polydisperse in size and to have defective microstructure. Some enhancement in the mechanical behavior of cement mortars was observed due to the addition of these nano-size materials. The contribution of these CNTs/CNFs to the mechanical strength of mortar specimens is similar to that of high quality CNTs incorporated in mortars by physical mixture.

  20. A Review on Nanomaterial Dispersion, Microstructure, and Mechanical Properties of Carbon Nanotube and Nanofiber Reinforced Cementitious Composites

    Shama Parveen

    2013-01-01

    Full Text Available Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs and nanofibers (CNFs have motivated the development of advanced nanocomposites with outstanding and multifunctional properties. After achieving a considerable success in utilizing these unique materials in various polymeric matrices, recently tremendous interest is also being noticed on developing CNT and CNF reinforced cement-based composites. However, the problems related to nanomaterial dispersion also exist in case of cementitious composites, impairing successful transfer of nanomaterials' properties into the composites. Performance of cementitious composites also depends on their microstructure which is again strongly influenced by the presence of nanomaterials. In this context, the present paper reports a critical review of recent literature on the various strategies for dispersing CNTs and CNFs within cementitious matrices and the microstructure and mechanical properties of resulting nanocomposites.

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

    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.

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

    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...

  3. Hydrogenation catalyst based on modified carbon nanofibers

    The aim of this work was to study the palladium-carboxylated carbon nanofibers (CNF) as a catalyst for the hydrogenation of nitrobenzene model reaction. It is shown that the efficiency of the catalyst obtained more than 6 times higher than that of the industrial counterpart (Pd/C).

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

    Graphical abstract: - Highlights: • Polyacrylonitrile (PAN) and zinc precursor were electrospun and heat-treated for preparing zinc oxide (ZnO) modified carbon nanofibers (CNF). • A facile synthesis of composite webs resulted in uniformly loaded ZnO on the surface of CNFs. • The composites showed significant hydrogen sulfide adsorption efficiency at 300 °C. • The flexible webs can be applied for mid-temperature desulfurization. - Abstract: Polyacrylonitrile (PAN) derived carbon nanofiber (CNF) webs loaded with zinc oxide (ZnO) were synthesized using electrospinning and heat treatment at 600 °C. Uniformly dispersed ZnO nanoparticles, clarified by X-ray diffraction and scanning electron microscopy, were observed on the surface of the nanofiber composites containing 13.6–29.5 wt% of ZnO. The further addition of ZnO up to 34.2 wt% caused agglomeration with a size of 50–80 nm. Higher ZnO contents led the concentrated ZnO nanoparticles on the surface of the nanofibers rather than uniform dispersion along the cross-section of the fiber. The flexible composite webs were crushed and tested for hydrogen sulfide (H2S) adsorption at 300 °C. Breakthrough experiments with the ZnO/CNF composite containing 25.7 wt% of ZnO for H2S adsorption showed three times higher ZnO utilization efficiency compared to pure ZnO nano powders, attributed to chemisorption of the larger surface area of well dispersed ZnO particles on nanofibers and physical adsorption of CNF

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

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

    2014-11-30

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

  6. Carbon nanofibers: a versatile catalytic support

    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.

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

    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.

  8. Fe3O4 nanoparticles-wrapped carbon nanofibers as high-performance anode for lithium-ion battery

    One-dimensional hierarchical nanostructures composed of Fe3O4 nanoparticles and carbon nanofibers (CNFs) have been successfully synthesized through a facile solvothermal method followed by a simple thermal annealing treatment. X-ray diffraction and electron microscopy reveal that Fe3O4 nanoparticles with a size of 80–100 nm are uniformly dispersed on CNFs. The Fe3O4/CNFs nanocomposites show an enhanced reversible capacity and excellent rate performance as anode for Li-ion battery. The reversible capacity of the nanocomposites retains 684 mAh g−1 after 55 cycles at 100 mA g−1. Even when cycled at various rate (100, 200, 500, 1000, and 2000 mA g−1) for 50 cycles, the capacity can recover to 757 mAh g−1 at the current of 100 mA g−1. The enhanced electrochemical performances are attributed to the characteristics of interconnected one-dimensional nanostructures that provide three-dimensional networks for Li-ion diffusion and electron transfer, and can further accommodate the volumetric change of Fe3O4 nanoparticles during charge–discharge cycling

  9. Carbon nanofiber/cobalt oxide nanopyramid core-shell nanowires for high-performance lithium-ion batteries

    An, Geon-Hyoung; Ahn, Hyo-Jin

    2014-12-01

    Carbon nanofiber (CNF)/Co3O4 nanopyramid core-shell nanowires (NWs) are synthesized using an electrospinning method followed by reduction and hydrothermal treatment in order to improve the capacity, cycle stability, and high-rate capability of the electrodes in Li ion batteries (LIBs). The morphology, crystal structure, and chemical states of all samples are investigated by means of field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. For comparison, conventional CNFs, octahedral Co3O4, and Co3O4/CNF composite electrodes are prepared. LIB cells fabricate with the CNF/Co3O4 nanopyramid core-shell NWs exhibit superb discharge capacity (1173 mAh g-1 at the 1st cycle), cycle stability (795 mAh g-1 at 50 cycles), high initial Coulombic efficiency (84.8%), and high-rate capability (570 mAh g-1 at a current density of 700 mA g-1) as compared to the conventional CNF, octahedral Co3O4, and Co3O4/CNF composite electrodes. The performance improvement is owing to the introduction of one-dimensional CNFs relative to efficient electron transport in the core region, extensive utilization of Co3O4 nanopyramids with high capacity grown closely on the CNFs in the shell region, and the network structures of the electrode relative to the improvement of Li ion diffusion.

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

    Koehne, Jessica E.

    2016-01-01

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

  11. Controlled Synthesis of Carbon Nanofibers Anchored with Zn(x)Co(3-x)O4 Nanocubes as Binder-Free Anode Materials for Lithium-Ion Batteries.

    Chen, Renzhong; Hu, Yi; Shen, Zhen; Chen, Yanli; He, Xia; Zhang, Xiangwu; Zhang, Yan

    2016-02-01

    The direct growth of complex ternary metal oxides on three-dimensional conductive substrates is highly desirable for improving the electrochemical performance of lithium-ion batteries (LIBs). We herein report a facile and scalable strategy for the preparation of carbon nanofibers (CNFs) anchored with ZnxCo3-xO4 (ZCO) nanocubes, involving a hydrothermal process and thermal treatment. Moreover, the size of the ZCO nanocubes was adjusted by the quantity of urea used in the hydrothermal process. Serving as a binder-free anode material for LIBs, the ZnCo2O4/CNFs composite prepared using 1.0 mmol of urea (ZCO/CNFs-10) exhibited excellent electrochemical performance with high reversible capacity, excellent cycling stability, and good rate capability. More specifically, a high reversible capacity of ∼600 mAh g(-1) was obtained at a current density of 0.5 C following 300 charge-discharge cycles. The excellent electrochemical performance could be associated with the controllable size of the ZCO nanocubes and synergistic effects between ZCO and the CNFs. PMID:26761129

  12. The synthesis of titanium carbide-reinforced carbon nanofibers

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

    2009-06-01

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

  13. The synthesis of titanium carbide-reinforced carbon nanofibers

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

  14. Synthesis of carbon nanofibers on copper particles

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

    2015-08-01

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

  15. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    Iwasaki, Tomohiro; Makino, Yuri; Fukukawa, Makoto; Nakamura, Hideya; Watano, Satoru

    2016-06-01

    To synthesize nitrogen-doped carbon nanofibers (N-CNFs) at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide) supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD) process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate) and then calcined at 1073 K for 1 h in oxidative (air), reductive (hydrogen-containing argon), or inert (pure argon) atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  16. Preparation of interconnected carbon nanofibers as electrodes for supercapacitors

    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

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

    Saeed Ghaffarpour Jahromi

    2015-09-01

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

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

    Yang Li

    2015-11-01

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

  19. IN-SITU SYNCHROTRON SAXS/WAXD STUDIES DURING MELT SPINNING OF MODIFIED CARBON NANOFIBER AND ISOTACTIC POLYPROPYLENE NANOCOMPOSITE

    The structural development of a nanocomposite, containing 95 wt% isotactic polypropylene (iPP) and 5 wt% modified carbon nanofiber (MCNF), during fiber spinning was investigated by in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. The modification of carbon nanofibers (CNFs) was accomplished by a chemical surface treatment using in situ polymerization of olefin segments to enhance its compatibility with iPP, where the iPP/MCNF nanocomposite was prepared by twostep blending to ensure the dispersion of MCNF. X-ray results showed that at low spin-draw ratios, the iPP/MCNF nanocomposite fiber exhibited much higher iPP crystalline orientation than the control iPP fiber. At higher spin-draw ratios, the crystalline orientation of the nanocomposite fiber and that of the pure iPP fiber was about the same. The crystallinity of the composite fiber was higher than that of the control iPP fiber, indicating the nucleating effect of the modified carbon nanofibers. The nanocomposite fiber also showed larger long periods at low spin-draw ratios. Measurements of mechanical properties indicated that the nanocomposite fiber with 5 wt% MCNF had much higher tensile strength, modulus and longer elongation to break. The mechanical enhancement can be attributed to the dispersion of MCNF in the matrix, which was confirmed by SEM results

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

    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

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

    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

  2. Improving interfacial adhesion with epoxy matrix using hybridized carbon nanofibers containing calcium phosphate nanoparticles for bone repairing.

    Gao, Xukang; Lan, Jinle; Jia, Xiaolong; Cai, Qing; Yang, Xiaoping

    2016-04-01

    Hybridized carbon nanofibers containing calcium phosphate nanoparticles (CNF/CaP) were investigated as osteocompatible nanofillers for epoxy resin. The CNF/CaP was produced by electrospinning mixture solution of polyacrylonitrile and CaP precursor sol-gel, followed by preoxidation and carbonization. The continuous and long CNF/CaP was ultrasonically chopped, mixed into epoxy resin and thermo-cured. Compared to pure CNFs with similar ultrasonication treatment, the shortened CNF/CaP reinforced composites demonstrated significant enhancement in flexural properties of epoxy composites, benefiting from the improved interfacial adhesion between CNF/CaP and resin matrix. The resulting composites also displayed good biocompatibility and sustained calcium ion release, which categorized them as promising materials for bone repairing. PMID:26838838

  3. Potential applications of nanofiber textile covered by carbon coatings

    Z. Rożek

    2008-03-01

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

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

    Highlights: • Electrospun carbon nanofiber webs were prepared by pyrolysis of polyacrylonitrile. • The webs as binder-free and current collector-free electrodes for SIBs and LIBs. • Different layer spacing and pore size for Li and Na lead different electrochemical behavior. • Electrochemical performances of the electrodes were high. - Abstract: A series of hard carbon nanofiber-based electrodes derived from electrospun polyacrylonitrile (PAN) nanofibers (PAN-CNFs) have been fabricated by stabilization in air at about 280 °C and then carbonization in N2 at heat treatment temperatures (HTT) between 800 and 1500 °C. The electrochemical performances of the binder-free, current collector-free carbon nanofiber-based anodes in lithium-ion batteries and sodium-ion batteries are systematically investigated and compared. We demonstrate the presence of similar alkali metal insertion mechanisms in both cases, but just the differences of the layer spacing and pore size available for lithium and sodium ion lead the discharge capacity delivered at sloping region and plateau region to vary from the kinds of alkali elements. Although the anodes in sodium-ion batteries show poorer rate capability than that in lithium-ion batteries, they still achieve a reversible sodium intercalation capacity of 275 mAh g−1 and similar cycling stability due to the conductive 3-D network, weakly ordered turbostratic structure and a large interlayer spacing between graphene sheets. The feature of high capacity and stable cycling performance makes PAN-CNFs to be promising candidates as electrodes in rechargeable sodium-ion batteries and lithium-ion batteries

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

    Highlights: • Electrically conductive CNF/HDPE nanocomposite were prepared by melt compounding. • The effect of processing on the nanocomposites macro and micro structures was analyzed. • 1.4 vol% CNF were required to construct a conductive network within the HDPE matrix. • An EMI SE of 42 dB was reported for 15 vol% CNF/HDPE nanocomposite. • An empirical model was developed to estimate the EMI SE. - Abstract: Electrically conductive polymer nanocomposite of high density polyethylene (HDPE) filled with carbon nanofibers (CNFs) were prepared by melt compounding in a batch mixer. The nanocomposite processing behavior was studied by monitoring the mixing torque vs. time as function of filler content. Scanning electron microscopy and optical microscopy were used to investigate the nanocomposite dispersion of nanofiller and the adhesion between the nanofiller and polymer matrix. The electrical and electromagnetic interference (EMI) shielding behaviors of the nanocomposite were reported as function of nanofibers concentration, and an empirical correlation related the EMI SE to the nanocomposite’s electrical resistivity was developed. Good level of CNF dispersion was evident despite the poor adhesion exhibited between the nanofibers and the HDPE matrix. At 1.5 vol% CNF loading, the nanocomposite exhibited an electrical volume resistivity of 105 Ω·cm. EMI shielding effectiveness was found to increase with increase in nanofiller concentration. In the 0.1–1.5 GHz frequency range, 2 mm thick plate made of 5 vol% CNF/HDPE nanocomposite exhibits an EMI shielding effectiveness of 20 dB

  6. Carbon nanofiber reinforced epoxy matrix composites and syntactic foams - mechanical, thermal, and electrical properties

    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

  7. Growth of carbon nanostructures on carbonized electrospun nanofibers with palladium nanoparticles

    This paper studies the mechanism of the formation of carbon nanostructures on carbon nanofibers with Pd nanoparticles by using different carbon sources. The carbon nanofibers with Pd nanoparticles were produced by carbonizing electrospun polyacrylonitrile (PAN) nanofibers including Pd(Ac)2. Such PAN-based carbon nanofibers were then used as substrates to grow hierarchical carbon nanostructures. Toluene, pyridine and chlorobenzine were employed as carbon sources for the carbon nanostructures. With the Pd nanoparticles embedded in the carbonized PAN nanofibers acting as catalysts, molecules of toluene, pyridine or chlorobenzine were decomposed into carbon species which were dissolved into the Pd nanoparticles and consequently grew into straight carbon nanotubes, Y-shaped carbon nanotubes or carbon nano-ribbons on the carbon nanofiber substrates. X-ray diffraction analysis and transmission electron microscopy (TEM) were utilized to capture the mechanism of formation of Pd nanoparticles, regular carbon nanotubes, Y-shaped carbon nanotubes and carbon nano-ribbons. It was observed that the Y-shaped carbon nanotubes and carbon nano-ribbons were formed on carbonized PAN nanofibers containing Pd-nanoparticle catalyst, and the carbon sources played a crucial role in the formation of different hierarchical carbon nanostructures

  8. Silicon Whisker and Carbon Nanofiber Composite Anode Project

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

  9. Silicon Whisker and Carbon Nanofiber Composite Anode Project

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

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

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

    2014-07-01

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

  11. Lightweight Structures Utilizing CNFs Project

    National Aeronautics and Space Administration — AxNano proposes a novel method for producing robust, high-volume, cost-effective carbon fibers in support of next-generation materials for structural composite...

  12. Fe{sub 3}O{sub 4} nanoparticles-wrapped carbon nanofibers as high-performance anode for lithium-ion battery

    Jiang, Fei; Zhao, Saihua; Guo, Jinxin; Su, Qingmei; Zhang, Jun; Du, Gaohui, E-mail: gaohuidu@zjnu.edu.cn [Zhejiang Normal University, Institute of Physical Chemistry (China)

    2015-08-15

    One-dimensional hierarchical nanostructures composed of Fe{sub 3}O{sub 4} nanoparticles and carbon nanofibers (CNFs) have been successfully synthesized through a facile solvothermal method followed by a simple thermal annealing treatment. X-ray diffraction and electron microscopy reveal that Fe{sub 3}O{sub 4} nanoparticles with a size of 80–100 nm are uniformly dispersed on CNFs. The Fe{sub 3}O{sub 4}/CNFs nanocomposites show an enhanced reversible capacity and excellent rate performance as anode for Li-ion battery. The reversible capacity of the nanocomposites retains 684 mAh g{sup −1} after 55 cycles at 100 mA g{sup −1}. Even when cycled at various rate (100, 200, 500, 1000, and 2000 mA g{sup −1}) for 50 cycles, the capacity can recover to 757 mAh g{sup −1} at the current of 100 mA g{sup −1}. The enhanced electrochemical performances are attributed to the characteristics of interconnected one-dimensional nanostructures that provide three-dimensional networks for Li-ion diffusion and electron transfer, and can further accommodate the volumetric change of Fe{sub 3}O{sub 4} nanoparticles during charge–discharge cycling.

  13. Alumina-carbon nanofibers nanocomposites obtained by spark plasma sintering for proton exchange membrane fuel cell bipolar plates

    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. Magnetite (Fe3O4)-filled carbon nanofibers as electro-conducting/superparamagnetic nanohybrids and their multifunctional polymer composites

    A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe3O4 nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields

  15. Ultrafine TiO2 Decorated Carbon Nanofibers as Multifunctional Interlayer for High-Performance Lithium-Sulfur Battery.

    Liang, Gemeng; Wu, Junxiong; Qin, Xianying; Liu, Ming; Li, Qing; He, Yan-Bing; Kim, Jang-Kyo; Li, Baohua; Kang, Feiyu

    2016-09-01

    Although lithium-sulfur (Li-S) batteries deliver high specific energy densities, lots of intrinsic and fatal obstacles still restrict their practical application. Electrospun carbon nanofibers (CNFs) decorated with ultrafine TiO2 nanoparticles (CNF-T) were prepared and used as a multifunctional interlayer to suppress the volume expansion and shuttle effect of Li-S battery. With this strategy, the CNF network with abundant space and superior conductivity can accommodate and recycle the dissolved polysulfides for the bare sulfur cathode. Meanwhile, the ultrafine TiO2 nanoparticles on CNFs work as anchoring points to capture the polysulfides with the strong interaction, making the battery perform with remarkable and stable electrochemical properties. As a result, the Li-S battery with the CNF-T interlayer delivers an initial reversible capacity of 935 mA h g(-1) at 1 C with a capacity retention of 74.2% after 500 cycles. It is believed that this simple, low-cost and scalable method will definitely bring a novel perspective on the practical utilization of Li-S batteries. PMID:27508357

  16. Structural transformation of vapor grown carbon nanofibers studied by HRTEM

    Vapor grown carbon nanofibers have been extensively manufactured and investigated in recent years. In this study commercially available vapor grown carbon nanofibers subjected to different processing and post processing conditions were studied employing high resolution TEM images. The analysis showed that the fibers consist primarily of conical nanofibers, but can contain a significant amount of bamboo nanofibers. Most 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. Fibers that have been heat treated to temperatures above 1,500 oC undergo a structural transformation with the ordered inner layers changing from a cone-helix structure to a highly ordered multiwall stacked cone structure. The bamboo nanofibers were found to have a tapered multiwall nanotube structure for the wall and a multishell fullerene structure for the cap of each segment, surrounded by a disordered outer layer. When these fibers are heat treated the disordered outer layers transform to an ordered multiwall nanotube structure and merge with the wall of each segment. The end caps of each segment transform from a smooth multiwall fullerene structure to one consisting of disjointed graphene planes. A reaction-diffusion mechanism is proposed to explain the growth and structure of the bamboo nanofibers.

  17. PREPARATION OF CARBON NANOFIBERS BY POLYMER BLEND TECHNIQUE

    2007-01-01

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

  18. Facile Fabrication of Binder-free Metallic Tin Nanoparticle/Carbon Nanofiber Hybrid Electrodes for Lithium-ion Batteries

    In this work, a Sn nanoparticle (NP)/carbon nanofiber (CNF) hybrid with unique structure has been designed and fabricated via electrospinning and subsequent heat treatment. The cell assembled by the binder-free Sn NP/CNF hybrid demonstrates an effective capacity (46 mAh g−1 at 200 mA g−1 after 200 cycles) with high coulombic efficiency (up to 99.8%), suggesting a facile strategy for the scalable fabrication of electrochemically stable electrodes for LIBs. For understanding the electrochemical behaviors of the metallic Sn and carbon nanofibers in the lithiation/delithiation process, in situ transmission electron microscopy was applied to study the single hybrid structure. In the first charge/discharge process, real-time size variation of the Sn NP and CNFs was mainly focused, suggesting a two-step lithiation process in the metallic Sn NP. Structural characterization also indicates an irreversible delithiation in a single Sn NP/CNF hybrid structure. The electrochemical performance based on influence of carbonization temperature has also been discussed. The results and fundamental understanding of the lithiation/delithiation in the Sn-based hybrid anodes enables the communities to design flexible high-performance electrodes based on metallic active materials in a rational way

  19. Growth and Characterization of Carbon Nanofibers on Fe/C-Fiber Textiles Coated by Deposition-Precipitation and Dip-Coating.

    Lee, Sang-Won; Lee, Chang-Seop

    2015-09-01

    This research was conducted to synthesize carbon nanofibers on C-fiber textiles, by thermal chemical vapor deposition (CVD) using Fe catalyst. The substrate, which was a carbon textile consisting of non-woven carbon fibers and attached graphite particles, was oxidized by nitric acid, before the deposition process. Hydroxyl groups were created on the C-fiber textile, due to the oxidization step. Fe(III) hydroxide was subsequently deposited on the oxidized surface of the C-fiber textile. To deposit ferric particles, two different methods were tested: (i) deposition-precipitation, and (ii) dip-coating. For the experiments using both types of catalyst deposition, the weight ratio of Fe to C-fiber textile was also varied. Ferric particles were reduced to iron after deposition, by using H2/N2 gas, and carbon nanofibers (CNFs) were grown by flowing ethylene gas. Properties of carbon nanofibers created like this were analyzed through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), N2-sorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectoscopy (XPS), Thermal analysis (TG/DTA), and Raman spectroscopy. In the case of the deposition-precipitation method, the results show that the diameter of carbon nanofibers grew up to 40-60 nm and 30-55 nm, at which the weight ratios of Fe catalyst to C-fiber textiles were 1:30 and 1:70, respectively. When Fe particles were deposited by the dip-coating method, the diameter of carbon nanofibers grew up to 40-60 nm and 25-30 nm, for the ratios of Fe catalyst to C-fiber textiles of 1:10 and 1:30, respectively. PMID:26716329

  20. Free-standing anode of N-doped carbon nanofibers containing SnO{sub x} for high-performance lithium batteries

    Zou, Mingzhong [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China); Li, Jiaxin, E-mail: ljx3012982@yahoo.com [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China); Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Wen, Weiwei; Lin, Yingbin [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China); Lai, Heng, E-mail: laiheng@fjnu.edu.cn [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China); Huang, Zhigao, E-mail: zghuang@fjnu.edu.cn [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China)

    2014-12-15

    Highlights: • Self-standing SnO{sub x} N-CNF electrodes were synthesized by electrospinning. • The SnO{sub x} N-CNFs anode exhibits high capacity, good cyclic stability, and excellent rate performance for lithium ion batteries. • The enhanced performance is ascribed to the synergetic effects between N-CNFs and SnO{sub x} nanoparticles. - Abstract: Free-standing paper of N-doped carbon nanofibers (NCNFs) containing SnO{sub x} was prepared by electrospinning. The structure and morphology of the sample were analyzed by XRD, XPS, SEM, and TEM. The results show that nitrogen atoms were successfully doped into CNFs. The SnO{sub x} were homogenously embedded in the N-doped CNFs via annealing treatment. Subsequently, the SnO{sub x} NCNF paper was cut into disks and used as anodes for lithium ion batteries (LIBs). The anodes of SnO{sub x} NCNFs exhibit excellent cycling stability and show high capacity of 520 mA h g{sup −1} tested at a 200 mA g{sup −1} after 100 cycles. More importantly, at a high current density of 500 mA g{sup −1}, a large reversible capacity of 430 mA h g{sup −1} after 100 cycles can still be obtained. The good electrochemical performance should be attributed to the good electronic conductivity from the NCNFs and the synergistic effects from NCNFs and SnO{sub x} materials.

  1. Treated Carbon Nanofibers for Storing Energy in Aqueous KOH

    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

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

    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

  3. Carbon Nanofibers as Catalyst Support for Noble Metals

    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

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

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

    2012-01-01

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

  5. Conductive Behaviors of Carbon Nanofibers Reinforced Epoxy Composites

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

    2008-01-01

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

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

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

    2007-02-01

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

  7. Synthesis of cellulose nanofiber composites for mechanical reinforcement and other advanced applications

    Xu, Xuezhu

    Cellulose nanofibers from bioresources have attracted intensive research interest in recent years due to their unique combination of properties including high strength and modulus, low density, biocompatibility/biodegradability and rich surface chemistry for functionalization. The nanofibers have been widely studied as nanoreinforcements in polymer nanocomposites; while the nanocomposite research is still very active, new research directions of using the nanofibers for hydrogels/aerogels, template for nanoparticle synthesis, scaffold, carbon materials, nanopaper, etc. have emerged. In this Ph.D. thesis, fundamental studies and application developments are performed on three types of cellulose nanofibers, i.e. cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and bacterial cellulose (BC). First CNCs and CNFs are systematically compared in terms of their effects on the mechanical properties, crystallization and failure behavior of the nanocomposites, which provides a guideline for the design of cellulose nanofiber reinforced composites. Second, CNFs and BC are used to develop core-shell carbon fibers and flexible carbon aerogels for energy storage applications. This part is focused on developing nanocarbon materials with multi-scale features. Lastly, hybrid CNC/CNF nanopaper with superior optical, mechanical, and electrical properties is developed and its application is demonstrated on a LED device.

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

    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

  9. Human cytochrome P450 3A4 and a carbon nanofiber modified film electrode as a platform for the simple evaluation of drug metabolism and inhibition reactions.

    Xue, Qiang; Kato, Dai; Kamata, Tomoyuki; Guo, Qiaohui; You, Tianyan; Niwa, Osamu

    2013-11-01

    Electrochemical biosensors consisting of cytochrome P450 enzyme modified electrodes have been developed to provide a simple method for screening the metabolism of a drug and its inhibitor. Here, we report a very simple electrochemically driven biosensor for detecting drug metabolism and its inhibition based on cytochrome P450 3A4 (CYP3A4) and a carbon nanofiber (CNF) modified film electrode without any other modified layers such as mediator films. Direct electron transfer (DET) between CYP3A4 and CNFs was observed at a formal potential of -0.302 V. The electrocatalytic reduction current increased with the addition of drugs including testosterone and quinidine. In contrast, the reduction current was greatly suppressed in the presence of ketoconazole, which is a CYP3A4 inhibitor. CNFs with high conductivity, a large surface area and sufficient edge planes provide a suitable microenvironment for achieving excellent DET and biocatalysis properties, which could not be observed when we used other carbon materials such as carbon nanotube (CNT) and carbon black (CB) modified electrodes, indicating that our system is promising as a new bioelectronic platform for electrochemical biosensing. PMID:24027778

  10. Preparation of C/Ni-NiO composite nanofibers for anode materials in lithium-ion batteries

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

    2013-11-01

    Carbon nanofibers (CNFs) embedded with various amounts of Ni and NiO nanoparticles (C/Ni-NiO) were prepared by electrospinning of polyacrylonitrile (PAN), followed by heat treatment. The structure and composition of the obtained C/Ni-NiO composite nanofibers were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results suggested that the morphology, nanofiber diameter, and the content of the Ni-NiO nanoparticles in the CNFs were controlled by different amounts of nickel acetate added into the PAN. The electrochemical measurements of a charge/discharge experiment and a cyclic voltammetry test indicated that the content and the size of Ni-NiO nanoparticles embedded in the CNFs had a great influence on the electrochemical performance of lithium-ion batteries. CNFs embedded with a certain content of Ni-NiO nanoparticles as binder-free anodes for rechargeable lithium-ion batteries exhibited improved electrochemical performance, including high reversible capacities, good capacity retention, and stable cycling performance. This is mainly ascribed to the formation of a well-distributed Ni-NiO nanoparticle structure and the buffering role of the carbon nanofiber matrix, together with the high theoretical capacity of NiO and the increase in electrode connectivity caused by the formation of electrochemically inactive Ni nanoparticles.

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

    Libya Ahmed Sbia

    2014-01-01

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

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

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

    2016-05-11

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

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

    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.

  14. Toward CH4 dissociation and C diffusion during Ni/Fe-catalyzed carbon nanofiber growth: A density functional theory study

    Fan, Chen; Zhou, Xing-Gui; Chen, De; Cheng, Hong-Ye; Zhu, Yi-An

    2011-04-01

    First-principles calculations have been performed to investigate CH4 dissociation and C diffusion during the Ni/Fe-catalyzed growth of carbon nanofibers (CNFs). Two bulk models with different Ni to Fe molar ratios (1:1 and 2:1) are constructed, and x-ray diffraction (XRD) simulations are conducted to evaluate their reliability. With the comparison between the calculated and experimental XRD patterns, these models are found to be well suited to reproduce the crystalline structures of Ni/Fe bulk alloys. The calculations indicate the binding of the C1 derivatives to the Ni/Fe closest-packed surfaces is strengthened compared to that on Ni(111), arising from the upshift of the weighted d-band centers of catalyst surfaces. Then, the transition states for the four successive dehydrogenation steps in CH4 dissociation are located using the dimer method. It is found that the energy barriers for the first three steps are rather close on the alloyed Ni/Fe and Ni surfaces, while the activation energy for CH dissociation is substantially lowered with the introduction of Fe. The dissolution of the generated C from the surface into the bulk of the Ni/Fe alloys is thermodynamically favorable, and the diffusion of C through catalyst particles is hindered by the Fe component. With the combination of density functional theory calculations and kinetic analysis, the C concentration in catalyst particles is predicted to increase with the Fe content. Meanwhile, other experimental conditions, such as the composition of carbon-containing gases, feedstock partial pressure, and reaction temperature, are also found to play a key role in determining the C concentration in bulk metal, and hence the microstructures of generated CNFs.

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

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

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

    Shao, Dongfeng; Wei, Qufu; Zhang, Liwei; Cai, Yibing; Jiang, Shudong

    2008-08-01

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

  17. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  18. Electrochemical characteristics of activated carbon nanofiber electrodes for supercapacitors

    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.

  19. Effects of increasing carbon nanofiber density in polyurethane composites for inhibiting bladder cancer cell functions.

    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

  20. High density carbon materials obtained at relatively low temperature by spark plasma sintering of carbon nanofibers

    Borrell, Amparo; Torrecillas, Ramon [Nanomaterials and Nanotechnology Research Center (CINN), Principado de Asturias - Consejo Superior de Investigaciones Cientificas (CSIC), Univ. de Oviedo, Parque Tecnologico de Asturias, Llanera (Spain); Fernandez, Adolfo [Fundacion ITMA, Parque Tecnologico de Asturias, Llanera (Spain); Merino, Cesar [Grupo Antolin Ingenieria, Burgos (Spain)

    2010-01-15

    Graphitic materials obtained at low temperatures are interesting for a wide range of industrial applications including bipolar plates. In this work, graphite based nanocomposites have been obtained starting from carbon nanofibers and a mixture of carbon nanofibers with 20 vol.% of alumina nanopowders. High density carbon components were obtained by using Spark Plasma Sintering at temperatures as low as 1500-1800 C for this kind of materials. The effect of spark plasma sintering parameters on the final density, and the mechanical and electrical properties of resulting nanocomposites have been investigated. Pure carbon nanofibers with around 90% of theoretical density and fracture strength of 60 MPa have been obtained at temperatures as low as 1500 C applying a pressure of 80 MPa during sintering. It has been proved that attrition milling is a suitable method for preparing homogeneous mixtures of carbon nanofibers and alumina powders. (orig.)

  1. Controllable preparation of multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets on electrospun carbon nanofibers for high-performance supercapacitors

    Graphical Abstract: Multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets grown on electrospun carbon nanofiber membranes were prepared via electrospinning combined with solution co-deposition for high-performance supercapacitor electrodes. - Highlights: • Ni-Co LDH@CNFhybridswerepreparedbyelectrospinningandsolutionco-deposition. • Ni-Co LDH@CNF hybrids show high electrochemical performance for supercapacitors. • This method can be extended to other bimetallic@CNF hybrids for electrode materials. - Abstract: Hybrid nanomaterials with hierarchical structures have been considered as one kind of the most promising electrode materials for high-performance supercapacitors with high capacity and long cycle lifetime. In this work, multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanorods/nanosheets on carbon nanofibers (CNFs) were prepared by electrospinning technique combined with one-step solution co-deposition method. Carbon nanofiber membranes were obtained by electrospinning of polyacrylonitrile (PAN) followed by pre-oxidation and carbonization. The successful growth of Ni-Co LDH with different morphologies on CNF membrane by using two kinds of auxiliary agents reveals the simplicity and universality of this method. The uniform and immense growth of Ni-Co LDH on CNFs significantly improves its dispersion and distribution. Meanwhile the hierarchical structure of carbon nanofiber@nickel-cobalt layered double hydroxide nanorods/nanosheets (CNF@Ni-Co LDH NR/NS) hybrid membranes provide not only more active sites for electrochemical reaction but also more efficient pathways for electron transport. Galvanostatic charge-discharge measurements reveal high specific capacitances of 1378.2 F g−1 and 1195.4 F g−1 (based on Ni-Co LDH mass) at 1 A g−1 for CNF@Ni-Co LDH NR and CNF@Ni-Co LDH NS hybrid membranes, respectively. Moreover, cycling stabilities for both hybrid membranes are

  2. Carbon Nanofibers as Catalyst Support for Noble Metals

    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...

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

    Manea, F.; Motoc, S.; Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Remes, A.; Schoonman, J.

    2012-01-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

  4. High-Resolution Imaging of Plasmid DNA in Liquids in Dynamic Mode Atomic Force Microscopy Using a Carbon Nanofiber Tip

    Kitazawa, Masashi; Ito, Shuichi; Yagi, Akira; Sakai, Nobuaki; Uekusa, Yoshitugu; Ohta, Ryo; Inaba, Kazuhisa; Hayashi, Akari; Hayashi, Yasuhiko; Tanemura, Masaki

    2011-08-01

    To understand the motion of DNA and DNA complexes, the real-time visualization of living DNA in liquids is quite important. Here, we report the high-resolution imaging of plasmid DNA in water using a rapid-scan atomic force microscopy (AFM) system equipped with a carbon nanofiber (CNF) probe. To achieve a rapid high-resolution scan, small SiN cantilevers with dimensions of 2 (width) × 0.1 (thickness) × 9 µm (length) and a bent end (tip view structure) were employed as base cantilevers onto which single CNFs were grown. The resonant frequencies of the cantilever were 1.5 MHz in air and 500 kHz in water, and the spring constant was calculated to be 0.1 N/m. Single CNFs, typically 88 nm in length, were formed on an array of the cantilevers in a batch process by the ion-irradiation method. An AFM image of a plasmid DNA taken in water at 0.2 fps (5 s/image) using a batch-fabricated CNF-tipped cantilever clearly showed the helix turns of the double strand DNA. The average helical pitch measured 3.4 nm (σ: 0.5 nm), which was in good agreement with that determined by the X-ray diffraction method, 3.4 nm. Thus, it is presumed that the combined use of the rapid-scan AFM system with the ion-induced CNF probe is promising for the dynamic analysis of biomolecules.

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

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

    2014-03-01

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

  6. Magnetite (Fe{sub 3}O{sub 4})-filled carbon nanofibers as electro-conducting/superparamagnetic nanohybrids and their multifunctional polymer composites

    Das, Arindam; Raffi, Muhammad; Megaridis, Constantine, E-mail: cmm@uic.edu [University of Illinois at Chicago, Department of Mechanical and Industrial Engineering (United States); Fragouli, Despina [Istituto Italiano di Tecnologia, Smart Materials, Nanophysics (Italy); Innocenti, Claudia [Universita di Firenze, INSTM Research Unit and Department of Chemistry (Italy); Athanassiou, Athanassia [Istituto Italiano di Tecnologia, Smart Materials, Nanophysics (Italy)

    2015-01-15

    A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe{sub 3}O{sub 4} nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields.

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

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

    2014-06-15

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

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

    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

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

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

    2014-10-01

    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.

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

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

    2014-01-01

    Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites) were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show...

  11. Synthesis, characterization and formation process of transition metal oxide nanotubes using carbon nanofibers as templates

    Mono and binary transition metal oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air. The transition metal oxide nanotubes were composed of nano-crystallites of metal oxides. The functional groups on the carbon nanofiber templates were essential for the coating of these templates: they acted as adsorption sites for the metal nitrates, ensuring a uniform metal oxide coating. During the removal of the carbon nanofiber templates by calcination in air, the metal oxide coatings promoted the combustion reaction between the carbon nanofibers and oxygen. - Graphical abstract: Mono and binary transition metal-oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air.

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

    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

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

    Lu, Weili; Luo, Chenghao; Li, Yu; Feng, Yiyu; Feng, Wei, E-mail: weifeng@tju.edu.cn; Zhao, Yunhui; Yuan, Xiaoyan, E-mail: yuanxy@tju.edu.cn [Tianjin University, School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials (China)

    2013-09-15

    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 Degree-Sign 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.

  14. Ellipsometric investigations of photonic crystals based on carbon nanofibers

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

    2010-01-01

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

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

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

    2015-09-15

    The morphology of polymers inside a confined space has raised great interest in recent years. However, polymer crystallization within a one-dimensional carbon nanostructure is challenging due to the difficulty of polar solvents carrying polymers to enter a nonpolar graphitic nanotube in bulk solution at normal temperature and pressure. Here we describe a method whereby nylon-11 was crystallized and periodically distributed on the individual graphitic nanocone structure within hollow carbon nanofibers (CNF). Differential scanning calorimetry and X-ray diffraction indicate that the nylon polymer is in the crystalline phase. A mechanism is suggested for the initiation of nanochannel flow in a bulk solvent as a prerequisite condition to achieve interior polymer crystallization. Selective etching of polymer crystals on the outer wall of CNF indicates that both surface tension and viscosity affect the flow within the CNF. This approach provides an opportunity for the interior functionalization of carbon nanotubes and nanofibers for applications in the biomedical, energy, and related fields. PMID:26313253

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

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

    2005-06-01

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

  17. Activated carbon nanofiber webs made by electrospinning for capacitive deionization

    Activated carbon fiber (ACF) webs with a non-woven multi-scale texture were fabricated from polyacrylonitrile (PAN), and their electrosorption performance in capacitive deionization for desalination was investigated. PAN nanofibers were prepared by electrospinning, followed by oxidative stabilization and activation with carbon dioxide at 750–900 °C, resulting in the ACF webs that were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and nitrogen adsorption. The results show that the as-made ACFs have a specific surface area of 335–712 m2/g and an average nanofiber diameter of 285–800 nm, which can be tuned by varying the activation temperature. With the ACF webs as an electrode, an electrosorption capacity as high as 4.64 mg/g was achieved on a batch-type electrosorptive setup operated at 1.6 V. The ACF webs made by electrospinning are of potential as an excellent electrode material for capacitive deionization for desalination.

  18. High performance carbon nanotube - polymer nanofiber hybrid fabrics

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

    2015-10-01

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

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

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

    2012-07-11

    Nanometer scale carbon fibers (carbon nanofibers) are of great interest to scientists and engineers in fields such as materials science, composite production, and energy storage due to their unique chemical, physical, and mechanical properties. Precursors currently used for production of carbon nanofibers are primarily from nonrenewable resources. Lignin is a renewable natural polymer existing in all high-level plants that is a byproduct of the papermaking process and a potential feedstock for carbon nanofiber production. The work presented here demonstrates a process involving the rapid freezing of an aqueous lignin solution, followed by sublimation of the resultant ice, to form a uniform network comprised of individual interconnected lignin nanofibers. Carbonization of the lignin nanofibers yields a similarly structured carbon nanofiber network. The methodology is not specific to lignin; nanofibers of other water-soluble polymers have been successfully produced. This nanoscale fibrous morphology has not been observed in traditional cryogel processes, due to the relatively slower freezing rates employed compared to those achieved in this study. PMID:22716198

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

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

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

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

    2016-01-01

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

  2. MnO-carbon hybrid nanofiber composites as superior anode materials for lithium-ion batteries

    MnO-carbon hybrid nanofiber composites are fabricated by electrospinning polyimide/manganese acetylacetonate precursor and a subsequent carbonization process. The composition, phase structure and morphology of the composites are characterized by scanning and transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The results indicate that the composites exhibit good nanofibrous morphology with MnO nanoparticles uniformly encapsulated by carbon nanofibers. The hybrid nanofiber composites are used directly as freestanding anodes for lithium-ion batteries to evaluate their electrochemical properties. It is found that the optimized MnO-carbon nanofiber composite can deliver a high reversible capacity of 663 mAh g−1, along with excellent cycling stability and good rate capability. The superior performance enables the composites to be promising candidates as an anode alternative for high-performance lithium-ion batteries

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

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

    2013-01-01

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

  4. Effect of carbon nanofibers on tensile and compressive characteristics of hollow particle filled composites

    The effect of presence of carbon nanofibers on the tensile and compressive properties of hollow particle filled composites is studied. Such composites, called syntactic foams, are known to have high specific modulus and low moisture absorption capabilities and are finding applications as core materials in aerospace and marine sandwich structures. The results of this study show that addition of 0.25 wt.% carbon nanofibers results in improvement in tensile modulus and strength compared to similar syntactic foam compositions that did not contain nanofibers. Compressive modulus decreased and strength remained largely unchanged for most compositions. Tensile and compressive failure features are analyzed using scanning electron microscopy.

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

    COLAVITA, PAULA

    2012-01-01

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

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

    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

  7. Anodes for glucose fuel cells made of carbonized nanofibers with embedded carbon nanotubes

    Prilutsky, Sabina; Cohen, Yachin; Zussman, Eyal; Makarov, Vadim; Bubis, Eugenia; Schechner, Pinchas

    2010-03-01

    Electrodes made of carbonized polyacrylonitryle nanofibers, with and without embedded multiwall carbon nanotubes (MWCNT) were fabricated by the electrospinning (ES) process and evaluated as anodes in a glucose fuel cell (FC). The effect of several processing and structural characteristics, such as the presence of MWCNTs, polymer concentration in the ES solution and silver electroless plating, on FC performance were measured The carbon electrodes were successful as anodes showing significant activity even without additional silver catalyst, with noticeable improvement by incorporation of MWCNTs. The orientation of graphitic layers along the fiber axis and the coherence of layer packing were shown to be important for enhanced electrode activity. The maximal values of open circuit voltage (OCV) and peak of power density (PPD) of unmetallized electrodes, 0.4 V and 30 μW/cm^2, were found for composite carbon nanofiber electrode. Electroless silver metallization leads to enhanced performance. Maximal values of OCV and PPD of silvered electrodes were measured to be about 0.9 V and 400 μW/cm^2. Thus, carbonized nanofibers with embedded MWCNTs may form a good basis for glucose FC anodes, but better metallization and cell-configuration allowing proper mixing are required.

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

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

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

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

    2013-05-01

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

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

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

    2014-10-24

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

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

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

    2016-02-01

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

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

    Naskar, Amit K.

    2015-08-04

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

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

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

    2011-01-01

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

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

    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)

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

    Zheng, Guangyuan

    2011-10-12

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

  16. High quality fluorescent cellulose nanofibers from endemic rice husk: isolation and characterization.

    Kalita, E; Nath, B K; Deb, P; Agan, F; Islam, Md R; Saikia, K

    2015-05-20

    Cellulose nanofibers (CNFs) with high crystallinity and purity were isolated from two endemic rice husk varieties using a hydrothermal approach followed by acid-alkali treatments and mechanical disruption. The CNFs isolated had a mean diameter of ∼ 35 nm. The TGA and DTG profiles showed good thermostability of the CNFs. The CNFs also showed a prominent photoluminescence peak at 404 nm with high quantum yield (∼ 58%). This is the first report on the native fluorescence property of nanocellulose in absence of any conjugated fluorescence molecule/dye. The CNFs further demonstrated appreciable hemocompatibility in the hemolysis test, exhibiting its potential for biomedical applications. PMID:25817673

  17. Supercritical CO2-driven,periodic patterning on one-dimensionals carbon nanomaterials

    2010-01-01

    One-dimensional carbon nano-materials,in particular carbon nanotubes (CNTs) and carbon nanofibers (CNFs),are of scientific and technological interest due to their satisfactory properties and ability to serve as templates for directed assembly.In this work,linear high density polyethylene (PE) was periodically decorated on CNTs and CNFs using a supercritical carbon dioxide (scCO2)antisolvent-induced polymer epitaxy (SAIPE) method,leading to nano-hybrid shish-kebab (NHSK) structures.The formation mechanism of different morphologies of PE lamellae on CNTs and CNFs has been discussed.Palladium nanoparticles were synthesized and immobilized on the PE/CNF NHSK structure with the assistance of scCO2.The obtained hierarchical nano-hybrid architecture may find applications in microfabrication and other related fields.

  18. Influence of oxygen on the growth of carbon nanotubes by the SiC surface decomposition method

    The influence of oxygen on the development of carbon nanotubes (CNTs) during the annealing process of the surface decomposition method on SiC(000-1) surfaces was investigated. In the case of annealing a SiC substrate under ultra-high vacuum conditions, carbon nanofibers (CNFs) form between the CNT layer and the substrate. However, CNTs form without CNFs by annealing the substrate in an oxygen atmosphere. The mean length of CNTs is longer than those formed without an oxygen atmosphere. From cross-sectional transmission electron microscopy images, it was found that oxygen plays an important role in CNT growth by the surface composition method.

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

    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.

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

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

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

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

    2012-05-01

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

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

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

  3. A Novel Process for High-efficient Synthesis of One-dimensional Carbon Nanoraaterials from Flames

    Xiang QI; Jun ZHANG; Chunxu PAN

    2008-01-01

    The substrate pre-treatment plays a key role in obtaining hollow-cored carbon nanotubes (CNTs) and solidcored carbon nanofibers (CNFs) from flames. This paper introduces a simply and high-efficient process by coating a NiSO4 or FeSO4 layer on the substrate as catalyst precursors. Comparing with the regular pretreatment methods, the present experiments showed that the coating pre-treatment provided the following advantages: 1) greatly shortening the synthesis time; 2) available variant substrates and carbon sources; 3) narrowing the diameters distribution. The sulfate is considered to be a crucial factor at the growth of CNTs and CNFs, because it increases the surface energy of catalyst particles and the surface specificity of sulfurs action in metallic grains. This novel process provides a possibility for high quality and mass production of CNTs and CNFs from flames.

  4. Ferric oxide nanoparticles decorated carbon nanotubes and carbon nanofibers: From synthesis to enhanced removal of phenol

    Hamza A. Asmaly

    2015-09-01

    Full Text Available In this work, ferric oxide nanoparticle decorated carbon fibers and carbon nanotubes (CNF/Fe2O3 and CNT/Fe2O3 were synthesized and characterized by scanning electron microscopy (SEM, thermogravimetric analysis (TGA, energy dispersive X-ray spectroscopy (EDS, transmission electron microscopy (TEM, X-ray diffraction (XRD, zeta potential and BET surface area analyzer. The prepared nanocomposites were evaluated or the removal of phenol ions from aqueous solution. The effects of experimental parameters, such as shaking speed, pH, contact time, adsorbent dosage and initial concentration, were evaluated for the phenol removal efficiency. The adsorption experimental data were represented by both the Langmuir and Freundlich isotherm models. The Langmuir isotherm model best fitted the data on the adsorption of phenol, with a high correlation coefficient. The adsorption capacities, as determined by the Langmuir isotherm model were 0.842, 1.098, 1.684 and 2.778 mg/g for raw CNFs, raw CNTs, CNF–Fe2O3 and CNT–Fe2O3, respectively.

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

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

    2015-01-25

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

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

    Highlights: • Sn0.92Sb0.08O2.04 nanoparticles as SnSb alloy precursor. • Carbon-coated SnSb nanoparticles were prepared and then embedded in carbon nanofibers. • The synergic effect of carbon coating and special structure improved cycling stability. - Abstract: Carbon coating and carbon nanofiber processes were used to enhance the cycling performance of SnSb alloys. Carbon-coated SnSb alloys were firstly prepared by a simple hydrothermal method to build the first protection, and then carbon-coated SnSb nanoparticles were embedded in carbon nanofibers via single-spinneret electrospinning followed by carbonization. The crystal structure of carbon-coated SnSb/C hybrid nanofibers was characterized by X-ray diffraction (XRD). The morphologies of carbon-coated SnSb alloys and hybrid nanofibers were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. The thermal stability of hybrid nanofibers were determined by thermogravimetric analysis (TGA). The electrochemical properties were investigated as a potential high-capacity anode material for lithium-ion batteries. The results showed that the hybrid nanofibers exhibited excellent electrochemical performance due to the special structure. The carbon shell can effectively hinder the agglomeration of SnSb alloys, while maintaining electronic conduction as well as accommodating drastic volume changes during lithium insertion and extraction and carbon nanofibers formed a further protection. The resultant carbon-coated SnSb nanoparticles dispersed in carbon nanofibers deliver a high capacity of 674 mA h g−1 and a good capacity retention of 68.7% after 50 cycles

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

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

    2014-01-01

    A carbon nanofiber-based luminol-biotin probe was synthesized for the sensitive chemiluminescence (CL) detection of a target protein by grafting luminol and biotin onto an oxidized carbon nanofiber. This carbon nanofiber was prepared by chemical vapor-deposition with methane in the presence of the Ni-Cu-MgO catalyst, which was followed by oxidization with HNO3-H2SO4 to produce a carboxyl group on the surface of the nanofiber. The material was grafted with luminol and biotin by means of a standard carbodiimide activation of COOH groups to produce corresponding amides. The substance was water-soluble and thus could be utilized as a sensitive CL probe for a protein assay. The probe showed highly specific affinity towards the biotin-labeled antibody via a streptavidin-biotin interaction. The detection limit for this model assay was approximately 0.2 pmol of the biotinized IgG spotted on a polyvinylidene fluoride (PVDF) membrane. Nonspecific binding to other proteins was not observed. Therefore, the synthesized carbon nanofiber-based CL probe may be useful for a sensitive and specific analysis of the target protein. PMID:25382040

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

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

    2016-08-01

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

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

    Baker, Sarah E.

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

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

    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.

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

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

    2011-01-01

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

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

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

  13. Electrochemical behavior of TiO2/carbon dual nanofibers

    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 Ω. 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

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

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

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

    William Curtin

    2016-02-01

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

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

    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

  17. Carbon functionalized TiO2 nanofibers for high efficiency photocatalysis

    TiO2 nanofibers (30–50 nm diameter), fabricated by the electro-spinning process, were modified with organo-silane agents via a coupling reaction and were grafted with carbohydrate molecules. The mixture was carbonized to produce a uniform coating of amorphous carbon on the surface of the TiO2 nanofibers. The TiO2@C nanofibers were characterized by high resolution electron microscopy (HRTEM), x-ray diffraction (XRD), x-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy. The photocatalytic property of the functional TiO2 and carbon nanocomposite was tested via the decomposition of an organic pollutant. The catalytic activity of the covalently functionalized nanocomposite was found to be significantly enhanced in comparison to unfunctionalized composite and pristine TiO2 due to the synergistic effect of nanostructured TiO2 and amorphous carbon bound via covalent bonds. The improvement in performance is due to bandgap modification in the 1D co-axial nanostructure where the anatase phase is bound by nano-carbon, providing a large surface to volume ratio within a confined space. The superior photocatalytic performance and recyclability of 1D TiO2@C nanofiber composites for water purification were established through dye degradation experiments. (papers)

  18. Carbon functionalized TiO2 nanofibers for high efficiency photocatalysis

    Raghava Reddy, Kakarla; Gomes, Vincent G.; Hassan, Mahbub

    2014-03-01

    TiO2 nanofibers (30-50 nm diameter), fabricated by the electro-spinning process, were modified with organo-silane agents via a coupling reaction and were grafted with carbohydrate molecules. The mixture was carbonized to produce a uniform coating of amorphous carbon on the surface of the TiO2 nanofibers. The TiO2@C nanofibers were characterized by high resolution electron microscopy (HRTEM), x-ray diffraction (XRD), x-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy. The photocatalytic property of the functional TiO2 and carbon nanocomposite was tested via the decomposition of an organic pollutant. The catalytic activity of the covalently functionalized nanocomposite was found to be significantly enhanced in comparison to unfunctionalized composite and pristine TiO2 due to the synergistic effect of nanostructured TiO2 and amorphous carbon bound via covalent bonds. The improvement in performance is due to bandgap modification in the 1D co-axial nanostructure where the anatase phase is bound by nano-carbon, providing a large surface to volume ratio within a confined space. The superior photocatalytic performance and recyclability of 1D TiO2@C nanofiber composites for water purification were established through dye degradation experiments.

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

    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

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

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

    2013-01-01

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

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

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

    2010-01-01

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

  2. Self-heating function of carbon nanofiber cement pastes

    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.

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

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

    2015-03-01

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

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

    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...

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

    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

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

    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.

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

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

    2016-01-01

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

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

    Matta Durga Prakash

    2016-08-01

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

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

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

    2016-06-01

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

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

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

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

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

    2015-03-30

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

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

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

    2014-01-28

    The discovery of oxygen and carbon monoxide tolerant [NiFe] hydrogenases was the first necessary step toward the definition of a novel generation of hydrogen fed biofuel cells. The next important milestone is now to identify and overcome bottlenecks limiting the current densities, hence the power densities. In the present work we report for the first time a comprehensive study of herringbone carbon nanofiber mesoporous films as platforms for enhanced biooxidation of hydrogen. The 3D network allows mediatorless hydrogen oxidation by the membrane-bound hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus. We investigate the key physico-chemical parameters that enhance the catalytic efficiency, including surface chemistry and hierarchical porosity of the biohybrid film. We also emphasize that the catalytic current is limited by mass transport inside the mesoporous carbon nanofiber film. Provided hydrogen is supplied inside the carbon film, the combination of the hierarchical porosity of the carbon nanofiber film with the hydrophobicity of the treated carbon material results in very high efficiency of the bioelectrode. By optimization of the whole procedure, current densities as high as 4.5 mA cm(-2) are reached with a turnover frequency of 48 s(-1). This current density is almost 100 times higher than when hydrogenase is simply adsorbed at a bare graphite electrode, and more than 5 times higher than the average of the previous reported current densities at carbon nanotube modified electrodes, suggesting that carbon nanofibers can be efficiently used in future sustainable H2/O2 biofuel cells. PMID:24296569

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

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

    2011-01-01

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

  14. The interfacial strength of carbon nanofiber epoxy composite using single fiber pullout experiments

    Carbon nanotubes and nanofibers are extensively researched as reinforcing agents in nanocomposites for their multifunctionality, light weight and high strength. However, it is the interface between the nanofiber and the matrix that dictates the overall properties of the nanocomposite. The current trend is to measure elastic properties of the bulk nanocomposite and then compare them with theoretical models to extract the information on the interfacial strength. The ideal experiment is single fiber pullout from the matrix because it directly measures the interfacial strength. However, the technique is difficult to apply to nanocomposites because of the small size of the fibers and the requirement for high resolution force and displacement sensing. We present an experimental technique for measuring the interfacial strength of nanofiber-reinforced composites using the single fiber pullout technique and demonstrate the technique for a carbon nanofiber-reinforced epoxy composite. The experiment is performed in situ in a scanning electron microscope and the interfacial strength for the epoxy composite was measured to be 170 MPa.

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

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

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

    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 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.

  17. Synthesis and characterization of electrospun carbon nanofiber supported Pt catalyst for fuel cells

    Graphical abstract: - Highlights: • The functionalized and optimized e-CNF has been prepared. • Increasing functionalization period, the fiber morphology slightly affected. • The suitability of the Pt/fe-CNF was studied in the lab made set-ups of PEMFC. - Abstract: Polyacrylonitrile polymer nanofibers were prepared using an electrospinner. These nanofibers were subjected to stabilization and carbonization processes. The electrospun carbon nanofibers (e-CNF) were functionalized using sulfuric acid and nitric acid under three different refluxing periods (i.e., 1f, 3f, and 5f) to optimize the functionalization level. The thermal stability of the obtained carbon supports was characterized by TGA. The Pt loaded carbon supports (20 wt%) for the three functionalized (1fe, 3fe, and 5fe-CNF) samples were prepared using chloroplatinic acid with ethylene glycol as the reducing agent. The dispersion of platinum on e-CNF and the size of Pt nanoparticles were characterized by HRSEM and HRTEM and the crystalline nature was confirmed by XRD. The surface area and pore size distribution were calculated from Brunner Emmett Teller method. The performance of five different samples such as Pt/C, Pt/1fe, 3fe, 5fe-CNF and e-CNF as electrodes and laboratory prepared hydrocarbon based sulfonated poly ether ether ketone (SPEEK) as electrolyte were studied in proton exchange membrane fuel cells (PEMFC) and the results were compared with commercially available Pt/C catalyst and Nafion-117 membrane

  18. Noble metal/functionalized cellulose nanofiber composites for catalytic applications.

    Gopiraman, Mayakrishnan; Bang, Hyunsik; Yuan, Guohao; Yin, Chuan; Song, Kyung-Hun; Lee, Jung Soon; Chung, Ill Min; Karvembu, Ramasamy; Kim, Ick Soo

    2015-11-01

    In this study, cellulose acetate nanofibers (CANFs) with a mean diameter of 325 ± 2.0 nm were electrospun followed by deacetylation and functionalization to produce anionic cellulose nanofibers (f-CNFs). The noble metal nanoparticles (RuNPs and AgNPs) were successfully decorated on the f-CNFs by a simple wet reduction method using NaBH4 as a reducing agent. TEM and SEM images of the nanocomposites (RuNPs/CNFs and AgNPs/CNFs) confirmed that the very fine RuNPs or AgNPs were homogeneously dispersed on the surface of f-CNFs. The weight percentage of the Ru and Ag in the nanocomposites was found to be 13.29 wt% and 22.60 wt% respectively; as confirmed by SEM-EDS analysis. The metallic state of the Ru and Ag in the nanocomposites was confirmed by XPS and XRD analyses. The usefulness of these nanocomposites was realized from their superior catalytic activity. In the aerobic oxidation of benzyl alcohol to benzaldehyde, the RuNPs/CNFs system gave a better yield of 89% with 100% selectivity. Similarly, the AgNPs/CNFs produced an excellent yield of 99% (100% selectivity) in the aza-Michael reaction of 1-phenylpiperazine with acrylonitrile. Mechanism has been proposed for the catalytic systems. PMID:26256382

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

    Kim, Soojung; Bajaj, Bharat; Byun, Chang Ki; Kwon, Soon-Jin; Joh, Han-Ik; Yi, Kwang Bok; Lee, Sungho

    2014-11-01

    Polyacrylonitrile (PAN) derived carbon nanofiber (CNF) webs loaded with zinc oxide (ZnO) were synthesized using electrospinning and heat treatment at 600 °C. Uniformly dispersed ZnO nanoparticles, clarified by X-ray diffraction and scanning electron microscopy, were observed on the surface of the nanofiber composites containing 13.6-29.5 wt% of ZnO. The further addition of ZnO up to 34.2 wt% caused agglomeration with a size of 50-80 nm. Higher ZnO contents led the concentrated ZnO nanoparticles on the surface of the nanofibers rather than uniform dispersion along the cross-section of the fiber. The flexible composite webs were crushed and tested for hydrogen sulfide (H2S) adsorption at 300 °C. Breakthrough experiments with the ZnO/CNF composite containing 25.7 wt% of ZnO for H2S adsorption showed three times higher ZnO utilization efficiency compared to pure ZnO nano powders, attributed to chemisorption of the larger surface area of well dispersed ZnO particles on nanofibers and physical adsorption of CNF.

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

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

    2016-11-01

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

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

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

    2006-01-01

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

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

    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 ...

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

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

    2011-01-01

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

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

    Nickel and other metal nanoparticles are known to be active as catalysts in the synthesis of carbon nanofibers. In this paper we investigate how dewetting and break-up of nickel thin films depends on film thickness, film–substrate interaction and pretreatment conditions. This is evaluated for films evaporated on oxidized silicon and fused silica substrates with or without tantalum coating, which were subsequently exposed to different pretreatment atmospheres (vacuum, nitrogen, air and hydrogen; 1 h, 650 °C). Atomic force microscopy, scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the films. Pretreated Ni films were subjected to a thermal catalytic chemical vapor deposition procedure with brief ethylene exposures (0.5–3 min, 635 °C). It was found that only on the spherical nanoparticles originating from a hydrogen pretreatment of a Ni film with Ta adhesion layer, homogeneously distributed, randomly-oriented, well-attached, and semi-crystalline carbon nanofibers be synthesized. - Highlights: • On the formation of nanoparticles required for carbon nanofiber (CNF) synthesis • Various evaporated thin films on oxidized silicon and fused silica: Ni and Ni/Ta • Pretreatment of nickel-based thin films in vacuum, nitrogen, air and hydrogen • Only on reduced Ni/Ta fast – within 3 min – initiation of CNF nucleation and growth

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

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

    2016-04-01

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

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

    Ding Nan

    2014-01-01

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

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

    Khalid Lafdi

    2007-01-01

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

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

    Graphical abstract: Display Omitted -- Highlights: • Flexible Si/SiO2/C composite nanofibers were introduced as Li–ion battery anodes. • SiO2 component of composite nanofibers facilitated the high flexibility. • Flexible Si/SiO2/C composite nanofibers were coated with CVD-carbon. • CVD carbon coating and SiO2 component led to high capacity retention. -- Abstract: High-capacity flexible electrode materials for high-energy lithium–ion batteries become critically important with technological improvements on portable and bendable electronic equipment such as rollup displays, implantable medical devices, active radio-frequency identification tags, and wearable devices. Although different types of bendable electrode materials have been introduced, it is very important to fabricate highly-flexible electrode materials with reasonable fabrication technique and high electrochemical performance similar to those of conventional high-capacity electrode materials. Herein, we introduced high-capacity, flexible Si/SiO2/C nanofiber composite anode materials by simple electrospinning and subsequent heat treatment processes. To further improve the long-term cycling performance, additional nanoscale carbon coating of flexible Si/SiO2/C nanofibers was performed by CVD technique. Electrochemical performance results showed that CVD carbon-coated flexible Si/SiO2/C nanofiber composites exhibited high capacity retention of 86.7% and high coulombic efficiency of 96.7% at the 50th cycle. It is, therefore, demonstrated that CVD carbon-coated flexible Si/SiO2/C nanofiber composites are promising anode material candidate for next-generation flexible and high-energy lithium–ion batteries

  9. Effect of Temperature on Morphology and Electrochemical Capacitive Properties of Electrospun Carbon Nanofibers and Nickel Hydroxide Composites

    Highlights: • Ni(OH)2 nanoflakes connected with electrospun carbon fibers were prepared. • Most Ni(OH)2 nanoflakes were converted to NiO at 350 °C, forming NiO microparticles. • The specific capacitance of the composites reached a maximum at 300 °C. - Abstract: Binder-free Ni(OH)2/carbon nanofiber composites used as supercapacitor electrodes were fabricated through the chemical precipitation of Ni(OH)2 on electrospun carbon nanofibers. These composites exhibited a hierarchical structure in which Ni(OH)2 nanoflakes connected with the carbon fiber network. We varied the annealing temperature to investigate the morphological progress and the subsequent electrochemical performance of the composite fibers. The hierarchical structure remained unchanged when the annealing temperature was lower than 300 °C. At 350 °C, most Ni(OH)2 was converted to NiO, and NiO peeled off from the fiber surface, forming NiO microparticles. Electrochemical measurements revealed that the specific capacity of the Ni(OH)2/carbon nanofiber composites increased with an increase in the annealing temperature and reached a maximum of 455 C/g at 300 °C. In addition, the Ni(OH)2/carbon nanofiber composites exhibited a favorable cycling stability after 2000 cycles without fading. The electrochemical performance of the composites was satisfactory because of the synergetic effect of the faradaic behavior of Ni(OH)2 and easily accessible electron transport in the carbon nanofiber network. At 350 °C, the peeling off and aggregation of NiO microparticles caused a reduction in the specific capacity of the Ni(OH)2/carbon nanofiber composites

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

    Kaerkitcha, Navaporn; Chuangchote, Surawut; Sagawa, Takashi

    2016-12-01

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

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

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

    2015-04-30

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

  12. Immobilization and release strategies for DNA delivery using carbon nanofiber arrays and self-assembled monolayers

    Peckys, Diana B [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Melechko, Anatoli V [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Simpson, Michael L [University of Tennessee in Knoxville, Knoxville, TN 37996-2200 (United States); McKnight, Timothy E [Measurement Science and Systems Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6006 (United States)], E-mail: peckysdb@ornl.gov

    2009-04-08

    We report a strategy for immobilizing dsDNA (double-stranded DNA) onto vertically aligned carbon nanofibers and subsequently releasing this dsDNA following penetration and residence of these high aspect ratio structures within cells. Gold-coated nanofiber arrays were modified with self-assembled monolayers (SAM) to which reporter dsDNA was covalently and end-specifically bound with or without a cleavable linker. The DNA-modified nanofiber arrays were then used to impale, and thereby transfect, Chinese hamster lung epithelial cells. This mechanical approach enables the transport of bound ligands directly into the cell nucleus and consequently bypasses extracellular and cytosolic degradation. Statistically significant differences were observed between the expression levels from immobilized and releasable DNA, and these are discussed in relation to the distinct accessibility and mode of action of glutathione, an intracellular reducing agent responsible for releasing the bound dsDNA. These results prove for the first time that an end-specifically and covalently SAM-bound DNA can be expressed in cells. They further demonstrate how the choice of immobilization and release methods can impact expression of nanoparticle delivered DNA.

  13. Immobilization and release strategies for DNA delivery using carbon nanofiber arrays and self-assembled monolayers

    We report a strategy for immobilizing dsDNA (double-stranded DNA) onto vertically aligned carbon nanofibers and subsequently releasing this dsDNA following penetration and residence of these high aspect ratio structures within cells. Gold-coated nanofiber arrays were modified with self-assembled monolayers (SAM) to which reporter dsDNA was covalently and end-specifically bound with or without a cleavable linker. The DNA-modified nanofiber arrays were then used to impale, and thereby transfect, Chinese hamster lung epithelial cells. This mechanical approach enables the transport of bound ligands directly into the cell nucleus and consequently bypasses extracellular and cytosolic degradation. Statistically significant differences were observed between the expression levels from immobilized and releasable DNA, and these are discussed in relation to the distinct accessibility and mode of action of glutathione, an intracellular reducing agent responsible for releasing the bound dsDNA. These results prove for the first time that an end-specifically and covalently SAM-bound DNA can be expressed in cells. They further demonstrate how the choice of immobilization and release methods can impact expression of nanoparticle delivered DNA.

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

    Yankun Zhan

    2011-01-01

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

  15. Utilization of compressed natural gas for the production of carbon nanotubes

    Kim-Yang Lee; Wei-Ming Yeoh; Siang-Piao Chai; Abdul Rahman Mohamed

    2012-01-01

    The present work aims at utilizing compressed natural gas (CNG) as carbon source for the synthesis of carbon nanotubes (CNTs) over CoO-MoO/Al2O3 catalyst via catalytic chemical vapor deposition (CCVD) method.The as-produced carbonaceous product was characterized by thermal gravimetric analyzer (TGA),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and Raman spectroscopy.The experimental finding shows that CNTs were successfully produced from CNG while carbon nanofibers (CNFs) were formed as the side products.In addition,the catalytic activity and lifetime were found sustained and prolonged,as compared with using high purity methane as carbon source.The present study suggests an alternative route which can effectively produce CNTs and CNFs using low cost CNG.

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

    Velmurugan Thavasi; Lala, Neeta L.; Seeram Ramakrishna

    2009-01-01

    We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature ...

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

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

    2016-08-01

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

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

    Seok-Hwan Park; Wan-Jin Lee

    2015-01-01

    Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires (CuO/CNF) as anodes for lithium ion batteries were prepared by coating the Cu2(NO3)(OH)3 on the surface of conductive and elastic CNF via electrophoretic deposition (EPD), followed by thermal treatment in air. The CuO shell stacked with nanoparticles grows radially toward the CNF core, which forms hierarchically mesoporous three-dimensional (3D) coaxial shell-core structure with abundant inner spaces in nanoparticle-s...

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

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

    2011-01-01

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

  20. Synthesis and photocatalytic property of porous metal oxides nanowires based on carbon nanofiber template

    Fan, Weiqiang; Li, Meng; Xu, Jinfu; Bai, Hongye; Zhang, Rongxian; Chen, Chao

    2015-11-01

    A series of porous metal oxides nanowires (Fe2O3, Co3O4, NiO and CuO) have been successfully synthesized, where commercial carbon nanofibers were used as the template. The obtained samples were systematically characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance (UV-Vis DR) spectra and transmission electron microscope (TEM). According to the photodegradation data, the porous metal oxides nanowires exhibit significantly photocatalytic activity for degrading tetracycline (TC). Furthermore, the porous Fe2O3 nanowires show the best photocatalytic performance among all the samples.

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

    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

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

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

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

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

    2008-01-01

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

  4. Direct measurement of hydrogen adsorption in carbon nanotubes/nanofibers by elastic recoil detection

    Physi- or chemi-sorption of hydrogen in solid materials offers a viable medium for hydrogen storage since the concentration of hydrogen can exceed that in its gaseous form at high compression. Due to their unique architecture, carbon nanotubes are potentially an excellent carbon-based adsorbent for hydrogen. In this work, we report direct measurements of hydrogen adsorption using elastic recoil detection analysis in single-walled, double-walled, and multi-walled nanotubes, as well as carbon nanofibers. Results are presented for hydrogen adsorption treatment at ambient temperature and above, where chemical rather than physical adsorption is anticipated. The results show that the concentration of hydrogen in all samples over the range of conditions investigated is below 1 wt.%, which is well below that required for a viable storage media

  5. Thermoplastic polybutadiene-based polyurethane/carbon nanofiber composites

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

    2014-01-01

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

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

    McKenzie, Janice L.

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

  7. Formation of carbon nanostructures containing single-crystalline cobalt carbides by ion irradiation method

    Wang, Zhipeng; Yusop, Zamri; Ghosh, Pradip; Hayashi, Yasuhiko; Tanemura, Masaki

    2011-02-01

    Carbon nanofibers (CNFs) with a diameter of 17 nm, and carbon nanoneedles (CNNs) with sharp tips have been synthesized on graphite substrates by ion irradiation of argon ions with the Co supplies rate of 1 and 3.4 nm/min, respectively. Energy dispersive X-ray spectrometry, combined with selected area electron diffraction patterns has been used to identify the chemical composition and crystallinity of these carbon nanostructures. The CNFs were found to be amorphous in nature, while the structures of the CNNs consisted of cubic CoCx, orthorhombic Co2C and Co3C depending on the cobalt content in the CNNs. The diameter of the carbide crystals was almost as large as the diameter of the CNN. Compared to the ion-induced nickel carbides and iron carbides, the formation of single-crystalline cobalt carbides might be due to the high temperature produced by the irradiation.

  8. Formation of carbon nanostructures containing single-crystalline cobalt carbides by ion irradiation method

    Carbon nanofibers (CNFs) with a diameter of 17 nm, and carbon nanoneedles (CNNs) with sharp tips have been synthesized on graphite substrates by ion irradiation of argon ions with the Co supplies rate of 1 and 3.4 nm/min, respectively. Energy dispersive X-ray spectrometry, combined with selected area electron diffraction patterns has been used to identify the chemical composition and crystallinity of these carbon nanostructures. The CNFs were found to be amorphous in nature, while the structures of the CNNs consisted of cubic CoCx, orthorhombic Co2C and Co3C depending on the cobalt content in the CNNs. The diameter of the carbide crystals was almost as large as the diameter of the CNN. Compared to the ion-induced nickel carbides and iron carbides, the formation of single-crystalline cobalt carbides might be due to the high temperature produced by the irradiation.

  9. Space proof complexity for random $3$-CNFs via a $(2-\\epsilon)$-Hall's Theorem

    Bonacina, Ilario; Galesi, Nicola; Huynh, Tony; Wollan, Paul

    2014-01-01

    We investigate the space complexity of refuting $3$-CNFs in Resolution and algebraic systems. No lower bound for refuting any family of $3$-CNFs was previously known for the total space in resolution or for the monomial space in algebraic systems. We prove that every Polynomial Calculus with Resolution refutation of a random $3$-CNF $\\phi$ in $n$ variables requires, with high probability, $\\Omega(n/\\log n)$ distinct monomials to be kept simultaneously in memory. The same construction also pro...

  10. Nanocomposite of Au Nanoparticles/Helical Carbon Nanofibers and Application in Hydrogen Peroxide Biosensor.

    Zhai, Mumu; Cui, Rongjing; Gu, Ning; Zhang, Genhua; Lin, Wang; Yu, Lingjun

    2015-06-01

    A combined sol-gel/hydrogen reduction method has been developed for the mass production of helical carbon nanofibers (HCNFs) by the pyrolysis of acetylene at 425 degrees C in the presence of NiO nanoparticles. The synthesized HCNFs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The helical-structured carbon nanofibers have a large specific surface area and excellent biocompatibility. A novel enzymatic hydrogen peroxide sensor was then successfully fabricated based on the nanocomposites containing HCNFs and gold nanoparticles (AuNPs). The results indicated that the Au/HCNFs nanocomposites exhibited excellent electrocatalytic activity to the reduction of H2O2, offering a wide linear range from 1.0 μM to 3157 μM with a detection limit as low as 0.46 μM. The apparent Michaelis-Menten constant of the biosensor was 0.61 mM. The as-fabricated biosensor showed a rapid and sensitive amperometric response to hydrogen peroxide with acceptable preparation reproducibility and excellent stability. Because of their low cost and high stability, these novel HCNFs represent seem to be a kind of promising biomaterial and may find wide new applications in scopes such as biocatalysis, immunoassay, environmental monitoring and so on. PMID:26369097

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

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

    2011-01-01

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

  12. Carbon Nanofibers-Supported Ni Catalyst for Hydrogen Production from Bio-Oil through Low-Temperature Reforming%一种适用于生物油低温制氢的碳纳米纤维促进的镍催化剂

    徐勇; 姜沛汶; 李全新

    2013-01-01

      氢气作为一种高热值的清洁能源广泛地应用于工业中.研究证明:生物质通过化学过程可以转化为多种气体燃料(氢气),液体燃料以及高附加值的化学品.生物质作为一种环境友好型再生洁净能源,其研究越来越受到关注.本文旨在探讨利用生物油为原料,通过水蒸汽重整方法制备富氢合成气的过程.利用均匀浸渍的方法制备了一种高分散的碳纳米纤维促进的镍(Ni/CNFs)催化剂,并将普通的Al2O3作为载体的Ni/Al2O3催化剂和Ni/CNFs作对比.研究了重整温度以及水蒸汽和碳摩尔比(nS/nC)对生物油水蒸汽重整制氢的影响.结果表明:碳纳米纤维作为载体用于生物油水蒸汽重整制氢的效果要远优于普通的Al2O3载体,利用22%Ni/CNFs催化剂时,在实验温度范围内(350-550°C),最高生物油转化率和氢气产率分别达到了94.7%和92.1%,通过研究重整条件以及对催化剂进行表征探讨了生物油在水蒸汽重整过程中催化剂的构效关系.%Hydrogen is a clean energy with high heat value that has been widely used in industry. Previous studies indicate that biomass can be converted in to gaseous fuels (hydrogen), liquid fuels and other chemicals. Biomass is the only renewable carbon resource and has attracted increasing attention because of the increasing price of oil and its environmental friendliness. To decrease energy consumption and minimize cost, it is very important to develop a process to produce hydrogen from bio-oil by low temperature steam reforming over non-noble metal catalysts. This work reports a carbon nanofibers-supported Ni (Ni/CNFs) catalyst prepared by the homogeneous impregnation method. The Ni/CNFs catalyst was successful y used to produce hydrogen via low-temperature (350-550 °C) steam reforming of bio-oil. The effects of temperature and water steam/carbon molar ratio (nS/nC) on the reforming of bio-oil were investigated. The highest carbon

  13. Effect of the nature the carbon precursor on the physico-chemical characteristics of the resulting activated carbon materials

    Carbon materials, including amorphous carbon, graphite, carbon nanospheres (CNSs) and different types of carbon nanofibers (CNFs) [platelet, herringbone and ribbon], were chemically activated using KOH. The pore structure of carbon materials was analyzed using N2/77 K adsorption isotherms. The presence of oxygen groups was analyzed by temperature programmed desorption in He and acid-base titration. The structural order of the materials was studied by X-ray diffraction and temperature programmed oxidation. The morphology and diameter distribution of CNFs and CNSs were characterized by transmission electron microscopy. The materials were also characterized by temperature-desorption programmed of H2 and elemental composition. The ways in which the different structures were activated are described, showing the type of pores generated. Relationships between carbon yield, removed carbon, activation degree and graphitic character were also examined. The oxygen content in the form of oxygen-containing surface groups increased after the activation giving qualitative information about them. The average diameter of both CNFs and CNSs was decreased after the activation process as consequence of the changes produced on the material surface.

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

    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

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

    Hao Dou

    2014-01-01

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

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

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

    2013-01-01

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

  17. Rhodium nanoparticles supported on carbon nanofibers as an arene hydrogenation catalyst highly tolerant to a coexisting epoxido group.

    Motoyama, Yukihiro; Takasaki, Mikihiro; Yoon, Seong-Ho; Mochida, Isao; Nagashima, Hideo

    2009-11-01

    Rhodium nanoparticles supported on a carbon nanofiber (Rh/CNF-T) show high catalytic activity toward arene hydrogenation under mild conditions in high turnover numbers without leaching the Rh species; the reaction is highly tolerant to epoxido groups, which often undergo ring-opening hydrogenation with conventional catalysts. PMID:19788269

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

    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

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

    Afzali, Moslem; Mostafavi, Ali; Shamspur, Tayebeh

    2016-11-01

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

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

    Baek Jong-Beom

    2008-01-01

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

  1. Palladium Catalysts Supported on Fishbone Carbon Nanofibers from Different Carbon Sources%碳源对鱼骨式纳米碳纤维及其负载的钯催化剂性能的影响

    周静红; 隋志军; 周兴贵; 袁渭康

    2008-01-01

    分别以甲烷、一氧化碳和乙烯为碳源合成了3种鱼骨式结构的纳米碳纤维(FCNF-C1, FCNF-CO和FCNF-C2), 并作为载体制备了3种钯催化剂(Pd 0.5%), 考察了在对苯二甲酸加氢精制中的催化活性,通过N2吸附-脱附、X射线衍射、程序升温脱附、电子透射显微镜及CO化学吸附等方法对载体以及催化剂的结构进行了表征. 结果表明,从不同碳源合成的纳米碳纤维(CNF)具有相似的直径和鱼骨式石墨层排列方式,但其物理化学性能差异较大,其中CO作为碳源得到的CNF具有最大的比表面积,最高的石墨化程度和最多的表面含氧基团;不同碳源的鱼骨式CNF负载的钯催化剂的活性为: Pd/FCNF-CO>Pd/FCNF-C1>Pd/FCNF-C2, 与Pd分散度的顺序一致. CNF的织构、晶体结构和表面化学等协同载体效应,决定了Pd金属在CNF上的分散状态以及催化性能,而CNF的石墨层排列方式对其影响很小.%Pd catalysts (0.5%Pd) supported on fishbone carbon nanofibers (FCNFs) from different carbon sources for terephthalic acid (TA) hydro-purification were prepared and investigated. CNFs from various carbon sources: CO (FCNF-CO), CH4 (FCNF-C1) and C2H4 (FCNF-C2) have been synthesized and characterized by N2 adsorption, XRD and TPD-MS. It is indicated that though they all possess similar fishbone structure, the FCNF from CO has the largest specific surface area, the highest graphitization degree and a large amount of surface groups, while the FCNF from C2H4 has the least specific surface area, the lowest graphitization degree and moderate surface groups. Pd/CNFs have been synthesized and characterized by TEM, N2 adsorption, XRD and CO chemisorption. The catalytic activity for TA purification follows the sequence: Pd/FCNF-CO>Pd/FCNF-C1>Pd/FCNF-C2, which is in accordance with the sequence of Pd dispersion. It is believed that rather than the graphene arrangement, the synergic support effect of pore structure, crystallinity and the

  2. Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance

    Yang, Zunxian; Lv, Jun; Pang, Haidong; Yan, Wenhuan; Qian, Kun; Guo, Tailiang; Guo, Zaiping

    2015-12-01

    Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg-1, a high reversible specific capacity of 560.5 mAhg-1 after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg-1 when cycled at the current density of 1000 mAg-1, indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

  3. Superhydrophocity via gas-phase monomers grafting onto carbon nanotubes

    Zha, Jinlong; Batisse, Nicolas; Claves, Daniel; Dubois, Marc; Frezet, Lawrence; Kharitonov, Alexander P.; Alekseiko, Leonid N.

    2016-05-01

    Superhydrophobic films were prepared using dispersions of fluorinated multi-walled carbon nanotubes (MWCNTs) or nanofibers (CNFs) in toluene. The grafting of polystyrene allowed stable dispersions to be obtained. The grafting of polystyrene (PS), polyacrylic acid (PAA) and polyaniline (PANI) onto nanofibers and MWCNTs was first evidenced by solid state NMR and Infrared Spectroscopy. The graft polymerization of styrene, acrylic acid and aniline monomers was initiated by radicals (dangling bonds) formed due to the initial fluorination. The process appeared as highly versatile and efficient for different polymers. The consumption of those radicals in the course of grafting was evidenced by EPR, through decrease of the spin density. The hydrophobic/hydrophilic character was tuned according to the grafted polymer nature, i.e. hydrophobic with PS or hydrophilic with PAA. Finally, in order to reach superhydrophobicity, films were prepared from CNFs or MWCNTs, irrespective of their average diameter, that allowed adequate structuring of the surface. The presence of fluorine atoms on their surface also favors superhydrophobicity. Water contact angles of 155 ± 2° and 159 ± 2° were measured for the films casted from fluorinated CNFs or MWCNTs with grafted polystyrene, respectively.

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

    Silver with a high theoretical capacity for lithium storage is an attractive alloy based anode for Li-ion batteries, but large volume changes associated with AgLix alloy formation leads to electrode cracking, pulverization and rapid capacity fading. A buffer matrix, like the electrospun hollow carbon nanofibers, can reduce this problem to a great extent. Herein, we demonstrate the facile synthesis of a free-standing, binder free Ag-C hybrid electrode through co-axial electrospinning, where well dispersed Ag nanoparticles are embedded in hollow carbon nanofibers. Using this approach, the long cycle life of carbon is complemented with the high lithium storage capacity of Ag, resulting in a high performance anode. The Ag-C composite electrode delivers a capacity of 739 mAh g−1 (>conventional graphite anodes) at 50 mA g−1, with ∼85% capacity retention after 100 cycles. In addition, the Ag-C composite nanofibers are highly porous and exhibit a large accessible surface area (∼726.9 m2 g−1) with an average pore diameter of ∼6.07 nm. The encapsulation of Ag in the hollow interiors not only provides additional lithium storage sites but also enhances the electronic conductivity, which combined with the reduced lithium diffusion path lengths in the nanofibers result in faster charge-discharge kinetics and hence a high rate performance

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

    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.

  6. Synthesis and characterization of magnetically active carbon nanofiber/iron oxide composites with hierarchical pore structures

    Polyacrylonitrile (PAN) solution containing the iron oxide precursor iron (III) acetylacetonate (AAI) was electrospun and thermally treated to produce electrically conducting, magnetic carbon nanofiber mats with hierarchical pore structures. The morphology and material properties of the resulting multifunctional nanofiber mats including the surface area and the electric and magnetic properties were examined using various characterization techniques. Scanning electron microscopy images show that uniform fibers were produced with a fiber diameter of ∼600 nm, and this uniform fiber morphology is maintained after graphitization with a fiber diameter of ∼330 nm. X-ray diffraction (XRD) and Raman studies reveal that both graphite and Fe3O4 crystals are formed after thermal treatment, and graphitization can be enhanced by the presence of iron. A combination of XRD and transmission electron microscopy experiments reveals the formation of pores with graphitic nanoparticles in the walls as well as the formation of magnetite nanoparticles distributed throughout the fibers. Physisorption experiments show that the multifunctional fiber mats exhibit a high surface area (200-400 m2 g-1) and their pore size is dependent on the amount of iron added and graphitization conditions. Finally, we have demonstrated that the fibers are electrically conducting as well as magnetically active.

  7. Synthesis and characterization of magnetically active carbon nanofiber/iron oxide composites with hierarchical pore structures

    Panels, Jeanne E.; Lee, Jinwoo; Park, Kang Yeol; Kang, Seung Yeon; Marquez, Manuel; Wiesner, Ulrich; Lak Joo, Yong

    2008-11-01

    Polyacrylonitrile (PAN) solution containing the iron oxide precursor iron (III) acetylacetonate (AAI) was electrospun and thermally treated to produce electrically conducting, magnetic carbon nanofiber mats with hierarchical pore structures. The morphology and material properties of the resulting multifunctional nanofiber mats including the surface area and the electric and magnetic properties were examined using various characterization techniques. Scanning electron microscopy images show that uniform fibers were produced with a fiber diameter of ~600 nm, and this uniform fiber morphology is maintained after graphitization with a fiber diameter of ~330 nm. X-ray diffraction (XRD) and Raman studies reveal that both graphite and Fe3O4 crystals are formed after thermal treatment, and graphitization can be enhanced by the presence of iron. A combination of XRD and transmission electron microscopy experiments reveals the formation of pores with graphitic nanoparticles in the walls as well as the formation of magnetite nanoparticles distributed throughout the fibers. Physisorption experiments show that the multifunctional fiber mats exhibit a high surface area (200-400 m2 g-1) and their pore size is dependent on the amount of iron added and graphitization conditions. Finally, we have demonstrated that the fibers are electrically conducting as well as magnetically active.

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

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

    2016-04-01

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

  9. Electrosorptive desalination by carbon nanotubes and nanofibres electrodes and ion-exchange membranes.

    Li, Haibo; Gao, Yang; Pan, Likun; Zhang, Yanping; Chen, Yiwei; Sun, Zhuo

    2008-12-01

    A novel membrane capacitive deionization (MCDI) device, integrating both the advantages of carbon nanotubes and carbon nanofibers (CNTs-CNFs) composite film and ion-exchange membrane, was proposed with high removal efficiency, low energy consumption and low cost. The CNTs-CNFs film was synthesized by low pressure and low temperature thermal chemical vapor deposition. Several experiments were conducted to compare desalination performance of MCDI with capacitive deionization (CDI), showing that salt removal of the MCDI system was 49.2% higher than that of the CDI system. The electrosorption isotherms of MCDI and CDI show both of them follow Langmuir adsorption, indicating no change in adsorption behavior when ion-exchange membranes are introduced into CDI system. The better desalination performance of MCDI than that of CDI is due to the minimized ion desorption during electrosorption. PMID:18929385

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

    Lu, Haibao; Gou, Jan

    2012-04-01

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

  11. Facile synthesis of functionalized graphene-palladium nanoparticle incorporated multicomponent TiO{sub 2} composite nanofibers

    Lee, Hyun-Gyu [Department of Nano-Science & Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Gopalan, Anantha-Iyengar [Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Sai-Anand, Gopalan [School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lee, Byung-Chan [Nano Convergence Practical Application Center, Daegu 891-5 (Korea, Republic of); Department of Chemistry Education, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kang, Shin-Won, E-mail: swkang@knu.ac.kr [School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lee, Kwang-Pill, E-mail: kplee@knu.ac.kr [Department of Chemistry Education, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2015-03-15

    Herein, we report the synthesis of functionalized graphene-Pd nanoparticle incorporated titanium dioxide composite nanofibers (designated as TiO{sub 2}@G(f)-Pd-CNFs) by combining electrospinning, hydrothermal and calcination processes. For comparison, functionalized graphene -incorporated titanium dioxide composite nanofibers (designated as TiO{sub 2}@G(f) CNFs) were also prepared. The structural, morphological and optical properties of the TiO{sub 2}-based composite nanofibers were characterized by field emission scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, X-Ray photoelectron spectroscopy, X-Ray diffraction analysis and thermogravimetry. The morphologies of the composite nanofibers were systematically investigated by transmission electron microscope and scanning electron microscope. The components in the composite nanofibers were identified with different morphologies: a fibrillar structure of the TiO{sub 2} nanofibers, irregular shaped graphene platelets and nanosized (sizes in the range of 4–12 nm) spherical Pd particles (around 8 nm). Thermogravimetry suggests that the inclusion of graphene and Pd improves the thermal stability of TiO{sub 2}. The photocatalytic degradation of methylene blue (MB) was examined in the presence of the catalyst, TiO{sub 2}@G(f)-Pd-CNFs under UV-irradiation and compared with TiO{sub 2} NFs and TiO{sub 2}@G(f) CNFs. The highest photodegradation efficiency was observed for TiO{sub 2}@G(f)-Pd-CNFs and attributed to the synergistic influence of the components, TiO{sub 2} NFs, Pd NPs and G(f). - Highlights: • Graphene and palladium nanoparticles were incorporated into titanium dioxide nanofibers. • Structural, morphological and microstructural properties were investigated. • Graphene layers are organized into stacks within the titanium dioxide nanofibers. • Raman spectrum suggests the interactions between the components in composite nanofibers. • The titanium dioxide

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

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

    2016-01-01

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

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

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

    2016-04-01

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

  14. Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

    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.

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

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

    2016-06-01

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

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

    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

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

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

    2016-06-01

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

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

    Kaerkitcha, Navaporn; Chuangchote, Surawut; Sagawa, Takashi

    2016-01-01

    Hollow carbon nanofibers (HCNFs) were prepared by electrospinning method with several coaxial nozzles, in which the level of the inner nozzle-end is adjustable. Core/shell nanofibers were prepared from poly(methyl methacrylate) (PMMA) as a pyrolytic core and polyacrylonitrile (PAN) as a carbon shell with three types of normal (viz. inner and outer nozzle-ends are balanced in the same level), inward, and outward coaxial nozzles. The influence of the applied voltage on these three types of coax...

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

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

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

    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. (paper)

  1. Transfer of vertically aligned carbon nanofibers to polydimethylsiloxane (PDMS) while maintaining their alignment and impalefection functionality.

    Pearce, Ryan C; Railsback, Justin G; Anderson, Bryan D; Sarac, Mehmet F; McKnight, Timothy E; Tracy, Joseph B; Melechko, Anatoli V

    2013-02-01

    Vertically aligned carbon nanofibers (VACNFs) are synthesized on Al 3003 alloy substrates by direct current plasma-enhanced chemical vapor deposition. Chemically synthesized Ni nanoparticles were used as the catalyst for growth. The Si-containing coating (SiN(x)) typically created when VACNFs are grown on silicon was produced by adding Si microparticles prior to growth. The fiber arrays were transferred to PDMS by spin coating a layer on the grown substrates, curing the PDMS, and etching away the Al in KOH. The fiber arrays contain many fibers over 15 μm (long enough to protrude from the PDMS film and penetrate cell membranes) and SiN(x) coatings as observed by SEM, EDX, and fluorescence microscopy. The free-standing array in PDMS was loaded with pVENUS-C1 plasmid and human brain microcapillary endothelial (HBMEC) cells and was successfully impalefected. PMID:23281833

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

    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.

  3. Synthesis of highly dispersed and active palladium/carbon nanofiber catalyst for formic acid electrooxidation

    Qin, Yuan-Hang; Yue-Jiang; Yang, Hou-Hua; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2011-05-01

    Highly dispersed and active palladium/carbon nanofiber (Pd/CNF) catalyst is synthesized by NaBH4 reduction with trisodium citrate as the stabilizing agent. The obtained Pd/CNF catalyst is characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The results show that the Pd nanoparticles with an average particle size of ca. 3.8 nm are highly dispersed on the CNF support even with a small ratio of citrate to Pd precursor, which is believed to be due to the pH adjustment of citrate stabilized colloidal Pd nanoparticles. The cyclic voltammetry and chronoamperometry techniques show that the obtained Pd/CNF catalyst exhibits good catalytic activity and stability for the electrooxidation of formic acid.

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

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

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

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

    2016-08-01

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

  6. Enhancement of Nitrite Reduction Kinetics on Electrospun Pd-Carbon Nanomaterial Catalysts for Water Purification.

    Ye, Tao; Durkin, David P; Hu, Maocong; Wang, Xianqin; Banek, Nathan A; Wagner, Michael J; Shuai, Danmeng

    2016-07-20

    We report a facile synthesis method for carbon nanofiber (CNF) supported Pd catalysts via one-pot electrospinning and their application for nitrite hydrogenation. A mixture of Pd acetylacetonate (Pd(acac)2), polyacrylonitrile (PAN), and nonfunctionalized multiwalled carbon nanotubes (MWCNTs) was electrospun and thermally treated to produce Pd/CNF-MWCNT catalysts. The addition of MWCNTs with a mass loading of 1.0-2.5 wt % (to PAN) significantly improved nitrite reduction activity compared to the catalyst without MWCNT addition. The results of CO chemisorption confirmed that the addition of MWCNTs increased Pd exposure on CNFs and hence improved catalytic activity. PMID:27387354

  7. Effect of the morphology of structured carbon nanomaterials on their oxidizability

    Savilov, S. V.; Ivanov, A. S.; Egorov, A. V.; Kirikova, M. N.; Arkhipova, E. A.; Lunin, V. V.

    2016-02-01

    The oxidation of multi-walled carbon nanotubes (MCNTs), nanofibers (CNFs), and few-layer graphite fragments (FLGFs) with a nitric acid solution was studied. The oxygen content in the functionalized derivatives was determined by X-ray photoelectron spectroscopy and thermal analysis. The results were correlated with the structural features of the nanomaterials revealed by high-resolution transmission electron microscopy and X-ray diffraction. The highest content of carboxyl groups was achieved by functionalization of carbon nanotubes with the conical position of graphene layers.

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

    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)

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

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

    2009-03-01

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

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

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

  11. Electrospun coaxial titanium dioxide/carbon nanofibers for use in anodes of dye-sensitized solar cells

    Graphical abstract: - Highlights: • Coaxial TiO2/carbon nanofibers (TCNFs) were fabricated by coaxial electrospinning. • After carbonization, TCNFs were formed with anatase TiO2 shell and carbon core. • The carbon core improved electron transport and minimized charge recombination. • The performance of TCNF-based DSSC device shows a high η value, 7.5%. - Abstract: TiO2/carbon coaxial-structured nanofibers (TCNFs), applied as photoanodes in dye-sensitized solar cells (DSSCs), were fabricated by coaxial electrospinning. The precursor of the TCNFs was electrospun using polyacrylonitrile in the core and a blend of titanium isopropoxide and polyvinylpyrrolidone in the shell. After calcination at 500 °C for 2 h in air and subsequent carbonization at 1000 °C for 2 h in nitrogen, the TCNFs were formed with nanocrystalline TiO2 in the shell layer and carbon in the core. The structure and morphology of the TCNFs were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The photovoltaic properties of the TCNF photoelectrode-based DSSCs were investigated by determining current density-voltage (J–V) curves, incident photon-to-current conversion efficiency (IPCE), and electrochemical impedance spectroscopy (EIS). The power conversion efficiency (PCE) of the TCNF photoelectrode-based DSSC was 7.5%, higher than those of DSSCs with TiO2 nanofiber (TNF)- and TiO2 nanoparticle (TNP)-based photoelectrodes. An increase in the electron transport and suppression of charge recombination were found with the carbon core and nanocrystalline TiO2 shell configuration of the TCNFs

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

    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.

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

    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

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

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

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

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

    2014-12-01

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

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

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

    2015-05-01

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

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

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

    2009-03-01

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

  18. Effect of carbon nanofiber addition in the mechanical properties and durability of cementitious materials

    Galao, O.

    2012-09-01

    Full Text Available This paper reports on recent work that is directed at studying the changes in the mechanical properties of Portland cement based mortars due to the addition of carbon nanofiber (CNF. Both flexural and compression strength has been determined and related to the CNF addition to the mix, to the curing time and to the porosity and density of the matrix. Also, corrosion of embedded steel rebars in CNF cement pastes exposed to carbonation and chloride attacks has been investigated. The increase in CNF addition implies higher corrosion intensity and higher levels of mechanical properties.En este artículo se han estudiado los cambios en las propiedades mecánicas de los morteros de cemento Portland debido a la adición de nanofibras de carbono (NFC. Se han determinado las resistencias a flexotracción y a compresión de los morteros en relación a la cantidad de NFC añadidas a la mezcla, al tiempo de curado y a la porosidad y densidad de los mismos. Además se han investigado los niveles de corrosión de barras de acero embebidas en pastas de cemento con NFC expuestos al ataque por carbonatación y por ingreso de cloruros. El aumento en el porcentaje de NFC añadido se traduce en un aumento la intensidad de corrosión registrada y una mejora de las propiedades mecánicas.

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

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

    2013-01-01

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

  20. Free-Standing Thin Webs of Activated Carbon Nanofibers by Electrospinning for Rechargeable Li-O2 Batteries.

    Nie, Hongjiao; Xu, Chi; Zhou, Wei; Wu, Baoshan; Li, Xianfeng; Liu, Tao; Zhang, Huamin

    2016-01-27

    Free-standing activated carbon nanofibers (ACNF) were prepared through electrospinning combining with CO2 activation and then used for nonaqueous Li-O2 battery cathodes. As-prepared ACNF based cathode was loosely packed with carbon nanofibers complicatedly overlapped. Owing to some micrometer-sized pores between individual nanofibers, relatively high permeability of O2 across the cathode becomes feasible. Meanwhile, the mesopores introduced by CO2 activation act as additional nucleation sites for Li2O2 formation, leading to an increase in the density of Li2O2 particles along with a size decrease of the individual particles, and therefore, flake-like Li2O2 are preferentially formed. In addition, the free-standing structure of ACNF cathode eliminates the side reactions about PVDF. As a result, the Li-O2 batteries with ACNF cathodes showed increased discharge capacities, reduced overpotentials, and longer cycle life in the case of full discharge and charge operation. This provides a novel pathway for the design of cathodes for Li-O2 battery. PMID:26691321

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

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

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

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

    2016-02-01

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

  3. Dynamic-mechanical and thermomechanical properties of cellulose nanofiber/polyester resin composites.

    Lavoratti, Alessandra; Scienza, Lisete Cristine; Zattera, Ademir José

    2016-01-20

    Composites of unsaturated polyester resin (UPR) and cellulose nanofibers (CNFs) obtained from dry cellulose waste of softwood (Pinus sp.) and hardwood (Eucalyptus sp.) were developed. The fiber properties and the influence of the CNFs in the dynamic-mechanical and thermomechanical properties of the composites were evaluated. CNFs with a diameter of 70-90 nm were obtained. Eucalyptus sp. has higher α-cellulose content than Pinus sp. fibers. The crystallinity of the cellulose pulps decreased after grinding. However, high values were still obtained. The chemical composition of the fibers was not significantly altered by the grinding process. Eucalyptus sp. CNF composites had water absorption close to the neat resin at 1 wt% filler. The dynamic-mechanical properties of Eucalyptus sp. CNFs were slightly increased and the thermal stability was improved. PMID:26572434

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

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

    2013-01-01

    Roč. 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/

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

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

    2016-01-01

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

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

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

  7. High-capacity Li2Mn0.8Fe0.2SiO4/carbon composite nanofiber cathodes for lithium-ion batteries

    Zhang, Shu; Li, Ying; Xu, Guanjie; Li, Shuli; Lu, Yao; Toprakci, Ozan; Zhang, Xiangwu

    2012-09-01

    Li2MnSiO4 has been considered as a promising cathode material with an extremely high theoretically capacity of 332 mAh g-1. However, due to its low intrinsic conductivity and poor structural stability, only about half of the theoretical capacity has been realized in practice and the capacity decays rapidly during cycling. To realize the high capacity and improve the cycling performance, Li2Mn0.8Fe0.2SiO4/carbon composite nanofibers were prepared by the combination of iron doping and electrospinning. X-ray diffraction, scanning electron microscope, and transmission electronic microscope were applied to characterize the Li2Mn0.8Fe0.2SiO4/carbon nanofibers. It was found that Li2Mn0.8Fe0.2SiO4 nanoparticles were embedded into continuous carbon nanofiber matrices, which formed free-standing porous mats that could be used as binder-free cathodes. The iron doping improved the conductivity and purity of the active material, and the carbon nanofiber matrix facilitated ion transfer and charge diffusion. As a result, Li2Mn0.8Fe0.2SiO4/carbon nanofiber cathodes showed promising improvement on reversible capacity and cycling performance.

  8. Three-Dimensional Force Sensing Device Using Carbon Nanofiber Polymer Composites: Design and Fabrication

    Chang, Fuh-Yu; Liu, Chia-Ming; Chen, Tse-Min; Chen, Chia-Ming; Lin, Yu-Hsien; Huang, Shu-Jiuan

    2012-06-01

    We propose an innovative three-dimensional force sensing device fabricated with carbon nanofiber (CNF) polymer composites. The device has four piezoresistive strain sensors made onto a polyimide substrate using surface patterning treatment and tilted-drop process with CNF polymer solutions. The proposed design and fabrication process is simpler than that of other three-dimensional force sensors and the device is suitable for mass production. The fabricated strain sensor properties using CNF polymer solutions with different composition ratios were investigated. An equation was derived using simple percolation theory to predict the conductivity of CNF polymer composites. The measured gauge factors were in the 4.84 to 17.68 range for CNF polymer composites with CNF 8.85-45.2 wt %. A programmable system on chip (PSoC) with built-in operational (OP) amplifier, analog-to-digital (AD) converter and multiplexer was used to develop a scanning and analyzing circuit for the three-dimensional force sensing device. The proposed integrated system was successfully applied to control a computer screen cursor.

  9. Carbon Nanofiber Arrays: A Novel Tool for Microdelivery of Biomolecules to Plants

    Davern, Sandra M.; McKnight, Timothy E.; Morrell-Falvey, Jennifer L.; Shpak, Elena D.; Kalluri, Udaya C.; Jelenska, Joanna; Greenberg, Jean T.; Mirzadeh, Saed

    2016-01-01

    Effective methods for delivering bioprobes into the cells of intact plants are essential for investigating diverse biological processes. Increasing research on trees, such as Populus spp., for bioenergy applications is driving the need for techniques that work well with tree species. This report introduces vertically aligned carbon nanofiber (VACNF) arrays as a new tool for microdelivery of labeled molecules to Populus leaf tissue and whole plants. We demonstrated that VACNFs penetrate the leaf surface to deliver sub-microliter quantities of solution containing fluorescent or radiolabeled molecules into Populus leaf cells. Importantly, VACNFs proved to be gentler than abrasion with carborundum, a common way to introduce material into leaves. Unlike carborundum, VACNFs did not disrupt cell or tissue integrity, nor did they induce production of hydrogen peroxide, a typical wound response. We show that femtomole to picomole quantities of labeled molecules (fluorescent dyes, small proteins and dextran), ranging from 0.5–500 kDa, can be introduced by VACNFs, and we demonstrate the use of the approach to track delivered probes from their site of introduction on the leaf to distal plant regions. VACNF arrays thus offer an attractive microdelivery method for the introduction of biomolecules and other probes into trees and potentially other types of plants. PMID:27119338

  10. Relationship Between Structure and Dynamic Mechanical Properties of a Carbon Nanofiber Reinforced Elastomeric Nanocomposite

    The tensile and dynamic mechanical properties of a nanocomposite, containing modified carbon nanofibers (MCNFs) homogenously dispersed in an elastomeric ethylene/propylene (EP) copolymer semicrystalline matrix (84.3 wt% P), have been correlated with the structure development. These properties were characterized by in situ synchrotron X-ray diffraction during stretching, dynamic mechanical analysis and X-ray analysis techniques over a wide temperature range. Upon sequential drawing, the tensile strength of the nanocomposite film was notably higher than that of the unfilled polymer even though both samples exhibited a similar amount of crystal fraction and the same degree of crystal orientation, revealing the effect of nanofiller reinforcement in the semicrystalline matrix. The mechanical spectra of the 10 wt% MCNF filled samples in both stretched and non-stretched states showed broadening of the elastic modulus at high temperatures, where the corresponding crystallinity index also decreased. It is conceivable that a significant fraction of chain orientation is induced in the vicinity of the nanofillers during stretching, and these stretched chains with reduced mobility significantly enhance the thermal mechanical properties

  11. Dielectric properties and conductivity of carbon nanofiber/semi-crystalline polymer composites

    The properties of semi-crystalline polymer nanocomposites are affected by the nanofillers directly and indirectly, as two phases, i.e., crystalline and amorphous, exist in the polymer. The effects of nanofillers on the two phases could be competitive. The dielectric properties and conductivity of carbon nanofibers (CNF)/semi-crystalline polymer nanocomposites are studied in this paper. CNF/polypropylene (PP) nanocomposites are prepared in experiment by melt blending. The resulting morphology and crystalline structure are characterized by means of differential scanning calorimetry, wide angle X-ray diffraction and scanning electron microscopy. The PP nanocomposite containing 5 wt.% CNF exhibits a surprisingly high dielectric constant under wide sweep frequencies attended by low dielectric loss. Its dielectric constant is >600 under lower frequency, and remains >200 at a frequency of 4000 Hz. The electrical and thermal conductivities of the nanocomposites are studied, and enhancements are seen with increased CNF content. Theoretical analyses on the physical properties are carried out by applying the existing models. Research results indicate that a common commercial plastic with good comprehensive performance, which exhibited the potential for applications in advanced electronics, was obtained by a simple industry benign technique

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

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

    2011-07-15

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

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

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-05-01

    Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires (CuO/CNF) as anodes for lithium ion batteries were prepared by coating the Cu2(NO3)(OH)3 on the surface of conductive and elastic CNF via electrophoretic deposition (EPD), followed by thermal treatment in air. The CuO shell stacked with nanoparticles grows radially toward the CNF core, which forms hierarchically mesoporous three-dimensional (3D) coaxial shell-core structure with abundant inner spaces in nanoparticle-stacked CuO shell. The CuO shells with abundant inner spaces on the surface of CNF and high conductivity of 1D CNF increase mainly electrochemical rate capability. The CNF core with elasticity plays an important role in strongly suppressing radial volume expansion by inelastic CuO shell by offering the buffering effect. The CuO/CNF nanowires deliver an initial capacity of 1150 mAh g-1 at 100 mA g-1 and maintain a high reversible capacity of 772 mAh g-1 without showing obvious decay after 50 cycles.

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

    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

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

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

    2009-01-01

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

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

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

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. PMID:27612735

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

    Velmurugan Thavasi

    2009-01-01

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

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

    Lala, Neeta L.; Thavasi, Velmurugan; Ramakrishna, Seeram

    2009-01-01

    We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness. PMID:22389589

  19. Carbon-Based Nano-Electro-Mechanical-Systems

    Kaul, A. B.; Khan, A. R.; Megerian, K. G.; Epp, L.; LeDuc, G.; Bagge, L.; Jennings, A. T.; Jang, D.; Greer, J. R.

    2011-01-01

    We provide an overview of our work where carbon-based nanostructures have been applied to two-dimensional (2D) planar and three-dimensional (3D) vertically-oriented nano-electro-mechanical (NEM) switches. In the first configuration, laterally oriented single-walled nanotubes (SWNTs) synthesized using thermal chemical vapor deposition (CVD) were implemented for forming bridge-type 2D NEMS switches, where switching voltages were on the order of a few volts. In the second configuration, vertically oriented carbon nanofibers (CNFs) synthesized using plasma-enhanced (PE) CVD have been explored for their potential application in 3D NEMS. We have performed nanomechanical measurements on such vertically oriented tubes using nanoindentation to determine the mechanical properties of the CNFs. Electrostatic switching was demonstrated in the CNFs synthesized on refractory metallic nitride substrates, where a nanoprobe was used as the actuating electrode inside a scanning-electron-microscope. The switching voltages were determined to be in the tens of volts range and van der Waals interactions at these length scales appeared significant, suggesting such structures are promising for nonvolatile memory applications. A finite element model was also developed to determine a theoretical pull-in voltage which was compared to experimental results.

  20. Integrated Carbon Nanostructures for Detection of Neurotransmitters.

    Sainio, Sami; Palomäki, Tommi; Tujunen, Noora; Protopopova, Vera; Koehne, Jessica; Kordas, Krisztian; Koskinen, Jari; Meyyappan, M; Laurila, Tomi

    2015-10-01

    Carbon-based materials, such as diamond-like carbon (DLC), carbon nanofibers (CNFs), and carbon nanotubes (CNTs), are inherently interesting for neurotransmitter detection due to their good biocompatibility, low cost and relatively simple synthesis. In this paper, we report on new carbon-hybrid materials, where either CNTs or CNFs are directly grown on top of tetrahedral amorphous carbon (ta-C). We show that these hybrid materials have electrochemical properties that not only combine the best characteristics of the individual "building blocks" but their synergy makes the electrode performance superior compared to conventional carbon based electrodes. By combining ta-C with CNTs, we were able to realize electrode materials that show wide and stable water window, almost reversible electron transfer properties and high sensitivity and selectivity for detecting dopamine in the presence of ascorbic acid. Furthermore, the sensitivity of ta-C + CNF hybrids towards dopamine as well as glutamate has been found excellent paving the road for actual in vivo measurements. The wide and stable water window of these sensors enables detection of other neurotransmitters besides DA as well as capability of withstanding higher potentials without suffering from oxygen and hydrogen evolution. PMID:26093378

  1. Fe{sub 3}O{sub 4}/carbon composite nanofiber absorber with enhanced microwave absorption performance

    Zhang, Ting [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Huang, Daqing [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Yang, Ying [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Kang, Feiyu, E-mail: fykang@tsinghua.edu.cn [Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Gu, Jialin [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer PAN/AAI/DMF solutions for electrospinning. Black-Right-Pointing-Pointer Fe{sub 3}O{sub 4}/carbon composite nanofibers as microwave absorbers. Black-Right-Pointing-Pointer Microwave absorption performance has been much enhanced than pure carbon naonfibers. Black-Right-Pointing-Pointer Microwave absorption mechanisms have been discussed as a key point. - Abstract: Fe{sub 3}O{sub 4}/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 Fe{sub 3}O{sub 4} 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 Fe{sub 3}O{sub 4}/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 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

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

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

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

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

    2015-04-01

    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.

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

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

    2008-01-01

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

  5. Corn-shape carbon nanofibers with dense graphite synthesized by microwave plasma-enhanced chemical vapor deposition

    Corn-shape carbon nanofibers (CCNFs) with metal-free tips have been synthesized by a microwave plasma-enhanced chemical-vapor deposition method using CH4 and H2 gasses. The CCNFs were grown on Ni/SiO2/Si and Ni/Mo mesh substrates using a bias-enhanced growth method, and they were analyzed by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The cones are composed of cylindrical pure graphite sheets, and have nanometer-sized tips and roots. The tips' apex angles of CCNFs have cone angles of 20 deg., 39 deg., and 60 deg. depending on the growth conditions such as substrate temperature

  6. Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes.

    Ren, Jiawen; Licht, Stuart

    2016-01-01

    Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotube) synthesis transforms CO2-gas dissolved in a 750 °C molten Li2CO3, by electrolysis, into O2-gas at a nickel electrode, and at a steel cathode into CNTs or carbon or nanofibers, CNFs. CNTs are synthesized at a 100-fold price reduction compared to conventional chemical vapour deposition, CVD, synthesis. The low cost conversion to a stable, value-added commodity incentivizes CO2 removal to mitigate climate change. The synthesis allows morphology control at the liquid/solid interface that is not available through conventional CVD synthesis at the gas/solid interface. Natural abundance (12)CO2 forms hollow CNTs, while equivalent synthetic conditions with heavier (13)CO2 favours closed core CNFs, as characterized by Raman, SEM and TEM. Production ease is demonstrated by the first synthesis of a pure (13)C multiwalled carbon nanofiber. PMID:27279594

  7. Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes

    Ren, Jiawen; Licht, Stuart

    2016-06-01

    Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotube) synthesis transforms CO2-gas dissolved in a 750 °C molten Li2CO3, by electrolysis, into O2-gas at a nickel electrode, and at a steel cathode into CNTs or carbon or nanofibers, CNFs. CNTs are synthesized at a 100-fold price reduction compared to conventional chemical vapour deposition, CVD, synthesis. The low cost conversion to a stable, value-added commodity incentivizes CO2 removal to mitigate climate change. The synthesis allows morphology control at the liquid/solid interface that is not available through conventional CVD synthesis at the gas/solid interface. Natural abundance 12CO2 forms hollow CNTs, while equivalent synthetic conditions with heavier 13CO2 favours closed core CNFs, as characterized by Raman, SEM and TEM. Production ease is demonstrated by the first synthesis of a pure 13C multiwalled carbon nanofiber.

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

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

    2015-07-01

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

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

    Numnuam, Apon; Thavarungkul, Panote; Kanatharana, Proespichaya

    2014-06-01

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

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

    Jo, Wan-Kuen, E-mail: wkjo@knu.ac.kr; Kang, Hyun-Jung

    2015-02-11

    Highlights: • A multiwalled carbon nanotube/titania composite nanofiber (MTCN) was synthesized. • Photocatalytic function of visible-activated MTCN was examined using tubular reactor. • MTCNs could be effectively used for the purification of sub-ppm gas-phase limonene. • The experimental results agreed well with Langmuir–Hinshelwood model. • Certain gas-phase intermediates were determined, but not for adsorbed intermediates. - Abstract: This study was conducted under visible-light exposure to investigate the photocatalytic characteristics of a multiwalled carbon nanotube/titania (TiO{sub 2}) composite nanofiber (MTCN) using a continuous-flow tubular reactor. The MTCN was prepared by a sol–gel process, followed by an electrospinning technique. The photocatalytic decomposition efficiency for limonene on the MTCN was higher than those obtained from reference TiO{sub 2} nanofibers or P25 TiO{sub 2}, and the experimental results agreed well with the Langmuir–Hinshelwood model. The CO concentrations generated during the photocatalysis did not reach levels toxic to humans. The mineralization efficiency for limonene on the MTCN was also higher than that for P25 TiO{sub 2}. Moreover, the mineralization efficiency obtained using the MTCN increased steeply from 8.3 to 91.1% as the residence time increased from 7.8 to 78.0 s, compared to the increase in the decomposition efficiencies for limonene from 90.1 to 99.9%. Three gas-phase intermediates (methacrolein, acetic acid, and limonene oxide) were quantitatively determined for the photocatalysis for limonene over the MTCN, whereas only two intermediates (acetic acid and limonene oxide) were quantitatively determined over P25 TiO{sub 2}. Other provisional gas-phase intermediates included cyclopropyl methyl ketone and 2-ethylbutanal.

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

    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.

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

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

    2014-09-01

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

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

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

    2016-08-01

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

  14. Imaging, Spectroscopic, Mechanical and Biocompatibility Studies of Electrospun Tecoflex(®) EG 80A Nanofibers and Composites Thereof Containing Multiwalled Carbon Nanotubes.

    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

  15. Influence of copper content on the electrocatalytic activity toward methanol oxidation of CoχCuy alloy nanoparticles-decorated CNFs

    Ghouri, Zafar Khan; Barakat, Nasser A. M.; Kim, Hak Yong

    2015-11-01

    In this study, CoCu alloy nanoparticles-incorporated carbon nanofibers are introduced as effective non precious electrocatalyst for methanol oxidation in alkaline medium. The introduced electrocatalyst has been synthesized by simple and effective process; electrospinning. Typically, calcination, in nitrogen atmosphere, of electrospun nanofibers composed of cobalt acetate, copper acetate and poly (vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The nanofibrous morphology and alloy structure have been confirmed by SEM, TEM and XRD analyses. Investigation of the electrocatalytic activity indicates that copper content has strong influence, the alloy nanoparticles having the composition Cu5%Co95% showed distinct high performance; 100 times higher than other formulations. Overall, the introduced study revealed the veil about the distinct role of copper in enhancing the electrocatalytic activity of cobalt-based materials.

  16. Carbon/SnO2/carbon core/shell/shell hybrid nanofibers: tailored nanostructure for the anode of lithium ion batteries with high reversibility and rate capacity

    Kong, Junhua; Liu, Zhaolin; Yang, Zhengchun; Tan, Hui Ru; Xiong, Shanxin; Wong, Siew Yee; Li, Xu; Lu, Xuehong

    2012-01-01

    A carbon/SnO2/carbon core/shell/shell hybrid nanofibrous mat was successfully prepared via single-spinneret electrospinning followed by carbonization and hydrothermal treatment. The morphology and structure of carbon/SnO2/carbon hybrid nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, wide-angle X-ray diffraction and X-ray photoelectron spectroscopy, and their electrochemical properties were studied as an anode in lithium ion batteries (LIBs). It is shown that the designed hybrid nanofibrous mat exhibits excellent electrochemical properties, including high reversible capacity with high columbic efficiency and impressive rate capacity. The greatly enhanced electrochemical performance is mainly due to the morphological stability and reduced diffusion resistance, which are induced by both the carbon core and deposited carbon skin. Furthermore, the embedded and de-aggregated SnO2 nanoparticles in the carbon phase, which are less than 10 nm in size, provide large numbers of reaction sites for lithium ions and ensure complete alloying with them.A carbon/SnO2/carbon core/shell/shell hybrid nanofibrous mat was successfully prepared via single-spinneret electrospinning followed by carbonization and hydrothermal treatment. The morphology and structure of carbon/SnO2/carbon hybrid nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, wide-angle X-ray diffraction and X-ray photoelectron spectroscopy, and their electrochemical properties were studied as an anode in lithium ion batteries (LIBs). It is shown that the designed hybrid nanofibrous mat exhibits excellent electrochemical properties, including high reversible capacity with high columbic efficiency and impressive rate capacity. The greatly enhanced electrochemical performance is mainly due to the morphological stability and reduced diffusion

  17. Si-Carbon Composite Nanofibers with Good scalability and Favorable Architecture for Highly Reversible Lithium Storage and Superb Kinetics

    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

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

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

    2013-03-01

    We report the mechanical property and electromagnetic interference shielding effectiveness (EMI SE) of poly(vinyl alcohol) (PVA)/graphene and PVA/multi-walled carbon nanotube (MWCNT) composite nanofibers prepared by electrospinning. The metal (Cu) was deposited on the resultant PVA composite nanofibers using metal deposition technique in order to improve the mechanical properties and EMI shielding properties. The resulting PVA composite nanofibers and Cu-deposited corresponding nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Tensile tests were performed on the PVA/graphene and PVA/MWCNT composite nanofibers. The tensile strength of the PVA/graphene and PVA/MWCNT composite nanofibers was found to be 19.2 +/- 0.3 MPa at graphene content - 6.0 wt% and 12.2 +/- 0.2 MPa at MWCNT content - 3.0 wt%, respectively. The EMI SE of the Cu-deposited PVA/graphene composite nanofibers was significantly improved compared to pure PVA/graphene composite nanofibers, and also depended on the thickness of Cu metal layer deposited on the PVA composite nanofibers. PMID:23755586

  19. Carbon-Confined SnO2-Electrodeposited Porous Carbon Nanofiber Composite as High-Capacity Sodium-Ion Battery Anode Material.

    Dirican, Mahmut; Lu, Yao; Ge, Yeqian; Yildiz, Ozkan; Zhang, Xiangwu

    2015-08-26

    Sodium resources are inexpensive and abundant, and hence, sodium-ion batteries are promising alternative to lithium-ion batteries. However, lower energy density and poor cycling stability of current sodium-ion batteries prevent their practical implementation for future smart power grid and stationary storage applications. Tin oxides (SnO2) can be potentially used as a high-capacity anode material for future sodium-ion batteries, and they have the advantages of high sodium storage capacity, high abundance, and low toxicity. However, SnO2-based anodes still cannot be used in practical sodium-ion batteries because they experience large volume changes during repetitive charge and discharge cycles. Such large volume changes lead to severe pulverization of the active material and loss of electrical contact between the SnO2 and carbon conductor, which in turn result in rapid capacity loss during cycling. Here, we introduce a new amorphous carbon-coated SnO2-electrodeposited porous carbon nanofiber (PCNF@SnO2@C) composite that not only has high sodium storage capability, but also maintains its structural integrity while ongoing repetitive cycles. Electrochemical results revealed that this SnO2-containing nanofiber composite anode had excellent electrochemical performance including high-capacity (374 mAh g(-1)), good capacity retention (82.7%), and large Coulombic efficiency (98.9% after 100th cycle). PMID:26252051

  20. Immobilization of CoCl2 (cobalt chloride) on PAN (polyacrylonitrile) composite nanofiber mesh filled with carbon nanotubes for hydrogen production from hydrolysis of NaBH4 (sodium borohydride)

    Composite nanofiber sheets containing multiwalled carbon nanotubes and cobalt chloride dispersed in PAN (polyacrylonitrile) were produced by an electrospinning technique. The synthesized PAN/CoCl2/CNTs composite nanofiber was used as the catalyst for hydrogen production from the hydrolysis of sodium borohydride. FT-IR characterization showed that the pretreated CNTs possess different organic functional groups which help improve the compatibility between CNTs and PAN organic polymer. SEM (scanning electron microscopy), TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray technique) were used to characterize the composite nanofiber and it was found that CNTs can be coaxially dispersed into the PAN nanofiber. During the hydrolysis of NaBH4, this PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity compared to the composite without CNTs doping. Kinetic analysis of NaBH4 hydrolysis shows that the reaction of NaBH4 hydrolysis based on this catalyst can be ascribed to the first-order reaction and the activation energy of the catalyst was approximately 52.857 kJ/mol. Meanwhile, the composite nanofiber catalyst shows excellent stability and reusability in the recycling experiment. - Highlights: • Composite nanofiber sheets were prepared via electrospinning. • PAN (polyacrylonitrile)/CoCl2 (cobalt chloride)/CNTs (carbon nanotubes) nanofiber was used as the catalyst for hydrogen production. • CNTs can be coaxially dispersed into the PAN nanofiber. • PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity. • The composite nanofiber catalyst shows excellent stability and reusability

  1. Hybrid Aluminum Composite Materials Based on Carbon Nanostructures

    Tatiana S. Koltsova

    2015-09-01

    Full Text Available We investigated formation of carbon nanofibers grown by chemical deposition (CVD method using an acetylene-hydrogen mixture on the surface of micron-sized aluminum powder particles. To obtain uniform distribution of the carbon nanostructures on the particles we deposited nickel catalyst on the surface by spraying from the aqueous solution of nickel nitrate. It was found that increasing the time of the synthesis lowers the rate of growth of carbon nanostructures due to the deactivation of the catalyst. The Raman spectroscopy measurements confirm the presence of disordered carbon corresponding to CNFs in the specimen. X-ray photoelectron spectroscopy showed the presence of aluminum carbide in the hot pressed samples. An aluminum composite material prepared using 1 wt.% CNFs obtained by uniaxial cold pressing and sintering showed 30% increase in the hardness compared to pure aluminum, whereas the composites prepared by hot pressing showed 80% increase in the hardness. Composite materials have satisfactory ductility. Thus, the aluminum based material reinforced with carbon nanostructures should be appropriate for creating high-strength and light compacts for aerospace and automotive applications and power engineering.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7355

  2. Electrodeposition of iron oxide nanorods on carbon nanofiber scaffolds as an anode material for lithium-ion batteries

    Iron oxide film with spaced radial nanorods is formed on the VGCF (vapor-grown carbon nanofiber) scaffolds by means of anodic electrodeposition. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy show that the iron oxide film deposited on the VGCF surface is α-Fe2O3 and consists of spaced radial nanorods having 16-21 nm in diameter after annealing at 400 deg. C. Galvanostatic charge/discharge results indicate that the α-Fe2O3/VGCF anode (970 mAh g-1) has higher capacity than bare α-Fe2O3 anode (680 mAh g-1) at 10 C current discharge. VGCF scaffolds fabricated by electrophoretic deposition favor the electron conduction, and the spaced radial nanorods on VGCFs facilitate the migration of lithium ion from the electrolyte. Electrochemical reactions between α-Fe2O3 and lithium ion are therefore improved significantly by this tailored architecture.

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

    Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

    2015-11-01

    Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS). PMID:26726677

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

    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

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

    Yuki Kaitsuka; Noriko Hayashi; Tomoko Shimokawa; Eiji Togawa; Hiromasa Goto

    2016-01-01

    Polymerization of aniline in the presence of cellulose nano-fiber (CNF) is carried out. We used dried CNF, CNF suspension, and CNF treated by enzyme and ultra-sonification to obtain polyaniline (PANI)/CNF as a synthetic polymer/natural nano-polymer composite. The polymerization proceeds on the surface of CNF as a nano-reaction field. Resultant composites show extended effective π-conjugation length because CNF as a reaction field in molecular level produced polymer with expanded coil structur...

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

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

    2016-02-17

    To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS2) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS2 nanosheets. The obtained hierarchical pBC-N/MoS2 nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm(-2) at η = 200 mV, low Tafel slope of 61 mV dec(-1), and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS2 nanosheets, the intimate connection between MoS2 nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS2-based nanocomposites as cost-effective HER eletrocatalysts. PMID:26302501

  7. Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion Battery Anodes

    2016-01-01

    The cost and practicality of greenhouse gas removal processes, which are critical for environmental sustainability, pivot on high-value secondary applications derived from carbon capture and conversion techniques. Using the solar thermal electrochemical process (STEP), ambient CO2 captured in molten lithiated carbonates leads to the production of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) at high yield through electrolysis using inexpensive steel electrodes. These low-cost CO2-derived CNTs and CNFs are demonstrated as high performance energy storage materials in both lithium-ion and sodium-ion batteries. Owing to synthetic control of sp3 content in the synthesized nanostructures, optimized storage capacities are measured over 370 mAh g–1 (lithium) and 130 mAh g–1 (sodium) with no capacity fade under durability tests up to 200 and 600 cycles, respectively. This work demonstrates that ambient CO2, considered as an environmental pollutant, can be attributed economic value in grid-scale and portable energy storage systems with STEP scale-up practicality in the context of combined cycle natural gas electric power generation.

  8. Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion Battery Anodes.

    Licht, Stuart; Douglas, Anna; Ren, Jiawen; Carter, Rachel; Lefler, Matthew; Pint, Cary L

    2016-03-23

    The cost and practicality of greenhouse gas removal processes, which are critical for environmental sustainability, pivot on high-value secondary applications derived from carbon capture and conversion techniques. Using the solar thermal electrochemical process (STEP), ambient CO2 captured in molten lithiated carbonates leads to the production of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) at high yield through electrolysis using inexpensive steel electrodes. These low-cost CO2-derived CNTs and CNFs are demonstrated as high performance energy storage materials in both lithium-ion and sodium-ion batteries. Owing to synthetic control of sp(3) content in the synthesized nanostructures, optimized storage capacities are measured over 370 mAh g(-1) (lithium) and 130 mAh g(-1) (sodium) with no capacity fade under durability tests up to 200 and 600 cycles, respectively. This work demonstrates that ambient CO2, considered as an environmental pollutant, can be attributed economic value in grid-scale and portable energy storage systems with STEP scale-up practicality in the context of combined cycle natural gas electric power generation. PMID:27163042

  9. Effects of potassium on Ni-K/Al2O3 catalysts in the synthesis of carbon nanofibers by catalytic hydrogenation of CO2.

    Chen, Ching S; Lin, Jarrn H; You, Jiann H; Yang, Kuo H

    2010-03-25

    Commercially available Ni/Al(2)O(3) samples containing various concentrations of potassium were used to achieve carbon deposition from CO(2) via catalytic hydrogenation. Experimental results show that K additives can induce the formation of carbon nanofibers or carbon deposition on Ni/Al(2)O(3) during the reverse water-gas shift reaction. This work proposes that the formation rate of carbon deposition depends closely on ensemble control, suggesting that the ensemble size necessary to form carbon may be approximately 0.5 potassium atoms. The results of CO(2) temperature-programmed desorption provide strong evidence that the new adsorption sites for CO(2) created on Ni-K/Al(2)O(3) closely depend upon the synthesis of carbon nanofibers. It is found that some potassium-related active phases obtained by calcination and reduction pretreatments can participate in the carbon deposition reaction. The formation pathway for carbon deposition suggests that the main source of carbon deposition is CO(2) and that the pathway is independent of the reaction products CO and CH(4) in the reverse water-gas shift reaction. PMID:19655780

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

    2016-01-01

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

  11. A novel nonenzymatic sensor based on CuO nanoneedle/graphene/carbon nanofiber modified electrode for probing glucose in saliva.

    Ye, Daixin; Liang, Guohai; Li, Huixiang; Luo, Juan; Zhang, Song; Chen, Hui; Kong, Jilie

    2013-11-15

    Here, we report on a novel nonenzymatic amperometric glucose sensor based on CuO nanoneedle/graphene/carbon nanofiber modified electrode. The results of the scanning electron microscopy indicate that electronic network was formed through their direct binding with the graphene/carbon nanofiber, which leads to larger active surface areas and faster electron transfer for the glucose sensor. High electrocatalytic activity toward the oxidation of glucose was observed with a rapid response (<2 s), a low detection limit (0.1 µM), a wide and useful linear range (1-5.3 mM) as well as good stability and repeatability. Moreover, the common interfering species, such as ascorbic acid, uric acid, dopamine and so forth did not cause obvious interference. The sensor can also be used for quantification of glucose concentration in real saliva samples. Therefore, this work has demonstrated a simple and effective sensing platform for nonenzymatic detection of glucose. PMID:24148397

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

    Susobhan Das; Jun Li; Rongqing Hui

    2015-01-01

    Micro- and nano-structured electrodes have the potential to improve the performance of Li-ion batteries by increasing the surface area of the electrode and reducing the diffusion distance required by the charged carriers. We report the numerical simulation of Lithium-ion batteries with the anode made of core-shell heterostructures of silicon-coated carbon nanofibers. We show that the energy capacity can be significantly improved by reducing the thickness of the silicon anode to the dimension ...

  13. Egg-Box Structure in Cobalt Alginate: A New Approach to Multifunctional Hierarchical Mesoporous N-Doped Carbon Nanofibers for Efficient Catalysis and Energy Storage.

    Li, Daohao; Lv, Chunxiao; Liu, Long; Xia, Yanzhi; She, Xilin; Guo, Shaojun; Yang, Dongjiang

    2015-08-26

    Carbon nanomaterials with both doped heteroatom and porous structure represent a new class of carbon nanostructures for boosting electrochemical application, particularly sustainable electrochemical energy conversion and storage applications. We herein demonstrate a unique large-scale sustainable biomass conversion strategy for the synthesis of earth-abundant multifunctional carbon nanomaterials with well-defined doped heteroatom level and multimodal pores through pyrolyzing electrospinning renewable natural alginate. The key part for our chemical synthesis is that we found that the egg-box structure in cobalt alginate nanofiber can offer new opportunity to create large mesopores (∼10-40 nm) on the surface of nitrogen-doped carbon nanofibers. The as-prepared hierarchical carbon nanofibers with three-dimensional pathway for electron and ion transport are conceptually new as high-performance multifunctional electrochemical materials for boosting the performance of oxygen reduction reaction (ORR), lithium ion batteries (LIBs), and supercapacitors (SCs). In particular, they show amazingly the same ORR activity as commercial Pt/C catalyst and much better long-term stability and methanol tolerance for ORR than Pt/C via a four-electron pathway in alkaline electrolyte. They also exhibit a large reversible capacity of 625 mAh g(-1) at 1 A g(-1), good rate capability, and excellent cycling performance for LIBs, making them among the best in all the reported carbon nanomaterials. They also represent highly efficient carbon nanomaterials for SCs with excellent capacitive behavior of 197 F g(-1) at 1 A g(-1) and superior stability. The present work highlights the importance of biomass-derived multifunctional mesoporous carbon nanomaterials in enhancing electrochemical catalysis and energy storage. PMID:27162980

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

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

    2012-11-16

    Glucose detection is very important in biological analysis, clinical diagnosis and the food industry, and especially for the routine monitoring of diabetes. This work presents an electrochemical approach to the detection of glucose based on Prussian blue (PB) nanostructures/carboxylic group-functionalized carbon nanofiber (FCNF) nanocomposites. The hybrid nanocomposites were constructed by growing PB onto the FCNFs. The obtained PB-FCNF nanocomposites were characterized by scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The mechanism of formation of PB-FCNF nanocomposites was investigated and is discussed in detail. The PB-FCNF modified glassy carbon electrode (PB-FCNF/GCE) shows good electrocatalysis toward the reduction of H(2)O(2), a product from the reduction of O(2) followed by glucose oxidase (GOD) catalysis of the oxidation of glucose to gluconic acid. Further immobilizing GOD on the PB-FCNF/GCE, an amperometric glucose biosensor was achieved by monitoring the generated H(2)O(2) under a relatively negative potential. The resulting glucose biosensor exhibited a rapid response of 5 s, a low detection limit of 0.5 μM, a wide linear range of 0.02-12 mM, a high sensitivity of 35.94 μA cm(-2) mM(-1), as well as good stability, repeatability and selectivity. The sensor might be promising for practical application. PMID:23090569

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

    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 μM, a wide linear range of 0.02–12 mM, a high sensitivity of 35.94 μA cm−2 mM−1, as well as good stability, repeatability and selectivity. The sensor might be promising for practical application. (paper)

  16. Amorphous flower-like molybdenum-sulfide-@-nitrogen-doped-carbon-nanofiber film for use in the hydrogen-evolution reaction.

    Zhang, Xiaoyan; Li, Libo; Guo, Yaxiao; Liu, Dong; You, Tianyan

    2016-06-15

    A novel amorphous flower-like molybdenum sulfides@nitrogen doped carbon nanofibers (MoSx@NCNFs) films are successfully synthesized by combining electrospinning, carbonization and a mild hydrothermal process. NCNFs, as a conductive substrate, can accelerate the electron transfer rate and depress the aggregation of MoSx nanoparticles. The resultant amorphous flower-like MoSx on NCNFs exposes abundant S(2-)/S2(2-) active edge sites which is of great importance for hydrogen evolution reaction (HER) catalytic performance. Electrochemical measurements demonstrate the superior electrocatalytic activity of MoSx@NCNFs toward HER deriving from the synergistic effect between NCNFs and amorphous MoSx. The overpotential is only 137mV to reach the current density of 10mAcm(-2) with a Tafel slope of 41mVdecade(-1) at MoSx@NCNFs. Meanwhile, MoSx@NCNFs exhibits satisfactory long-time stability for HER. Noteworthy, the obtained composites show a free-standing structure which can be directly used as electrode materials. This work provides a feasible way to design promising noble-metal free electrocatalysts in the aspect of energy conversion. PMID:27015391

  17. Hierarchical Electrospun and Cooperatively Assembled Nanoporous Ni/NiO/MnOx/Carbon Nanofiber Composites for Lithium Ion Battery Anodes.

    Bhaway, Sarang M; Chen, Yu-Ming; Guo, Yuanhao; Tangvijitsakul, Pattarasai; Soucek, Mark D; Cakmak, Miko; Zhu, Yu; Vogt, Bryan D

    2016-08-01

    A facile method to fabricate hierarchically structured fiber composites is described based on the electrospinning of a dope containing nickel and manganese nitrate salts, citric acid, phenolic resin, and an amphiphilic block copolymer. Carbonization of these fiber mats at 800 °C generates metallic Ni-encapsulated NiO/MnOx/carbon composite fibers with average BET surface area (150 m(2)/g) almost 3 times higher than those reported for nonporous metal oxide nanofibers. The average diameter (∼900 nm) of these fiber composites is nearly invariant of chemical composition and can be easily tuned by the dope concentration and electrospinning conditions. The metallic Ni nanoparticle encapsulation of NiO/MnOx/C fibers leads to enhanced electrical conductivity of the fibers, while the block copolymers template an internal nanoporous morphology and the carbon in these composite fibers helps to accommodate volumetric changes during charging. These attributes can lead to lithium ion battery anodes with decent rate performance and long-term cycle stability, but performance strongly depends on the composition of the composite fibers. The composite fibers produced from a dope where the metal nitrate is 66% Ni generates the anode that exhibits the highest reversible specific capacity at high rate for any composition, even when including the mass of the nonactive carbon and Ni(0) in the calculation of the capacity. On the basis of the active oxides alone, near-theoretical capacity and excellent cycling stability are achieved for this composition. These cooperatively assembled hierarchical composites provide a platform for fundamentally assessing compositional dependencies for electrochemical performance. Moreover, this electrospinning strategy is readily scalable for the fabrication of a wide variety of nanoporous transition metal oxide fibers. PMID:27399605

  18. Preparation and characterization of Li3V2(PO4)3 grown on carbon nanofiber as cathode material for lithium-ion batteries

    Bead-like nanocomposite Li3V2(PO4)3 (LVP) grown on carbon nanofiber (CNF) have been prepared by electrospinning and heat-treatment. The primary LVP crystals are squeezed together and grow outward because of the limitation of the reaction space for LVP precursors in PVP fiber, accompanying with the carbon nanofibers shrank in diameters. Compared with the traditional carbon-coated LVP, the combination of the “beads” (LVP nanoparticles) and the “string” (carbon fiber) are effective in conductivity and stability. A small amount of carbon content (5.27 wt%) in LVP/CNF is sufficient to enhance the rate performance and cycle ability. The initial discharge capacity of LVP/CNF is 196 mAh g−1 at 0.1 C, which is very close to the theoretical value (197 mAh g−1) of pure LVP in 3.0-4.8 V. In the long-term cycles at 20C-rate, LVP/CNF delivers the initial capacities of 127.5 mAh g−1, and remains 102.0 mAh g−1 at the 1000th cycle. Bead-like structure of LVP nanoparticles grown in carbon fibers is stable in thousands charge/discharge cycles at high current rate

  19. Factoring-in agglomeration of carbon nanotubes and nanofibers for better prediction of their toxicity versus asbestos

    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

  20. Synthesis of palladium/helical carbon nanofiber hybrid nanostructures and their application for hydrogen peroxide and glucose detection.

    Jia, Xueen; Hu, Guangzhi; Nitze, Florian; Barzegar, Hamid Reza; Sharifi, Tiva; Tai, Cheuk-Wai; Wågberg, Thomas

    2013-11-27

    We report on a novel sensing platform for H2O2 and glucose based on immobilization of palladium-helical carbon nanofiber (Pd-HCNF) hybrid nanostructures and glucose oxidase (GOx) with Nafion on a glassy carbon electrode (GCE). HCNFs were synthesized by a chemical vapor deposition process on a C60-supported Pd catalyst. Pd-HCNF nanocomposites were prepared by a one-step reduction free method in dimethylformamide (DMF). The prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The Nafion/Pd-HCNF/GCE sensor exhibits excellent electrocatalytic sensitivity toward H2O2 (315 mA M(-1) cm(-2)) as probed by cyclic voltammetry (CV) and chronoamperometry. We show that Pd-HCNF-modified electrodes significantly reduce the overpotential and enhance the electron transfer rate. A linear range from 5.0 μM to 2.1 mM with a detection limit of 3.0 μM (based on the S/N = 3) and good reproducibility were obtained. Furthermore, a sensing platform for glucose was prepared by immobilizing the Pd-HCNFs and glucose oxidase (GOx) with Nafion on a glassy carbon electrode. The resulting biosensor exhibits a good response to glucose with a wide linear range (0.06-6.0 mM) with a detection limit of 0.03 mM and a sensitivity of 13 mA M(-1) cm(-2). We show that small size and homogeneous distribution of the Pd nanoparticles in combination with good conductivity and large surface area of the HCNFs lead to a H2O2 and glucose sensing platform that performs in the top range of the herein reported sensor platforms. PMID:24180258

  1. Hollow nitrogen-containing core/shell fibrous carbon nanomaterials as support to platinum nanocatalysts and their TEM tomography study

    Zhou, Cuifeng; Liu, Zongwen; Du, Xusheng; Mitchell, David Richard Graham; Mai, Yiu-Wing; Yan, Yushan; Ringer, Simon

    2012-03-01

    Core/shell nanostructured carbon materials with carbon nanofiber (CNF) as the core and a nitrogen (N)-doped graphitic layer as the shell were synthesized by pyrolysis of CNF/polyaniline (CNF/PANI) composites prepared by in situ polymerization of aniline on CNFs. High-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared and Raman analyses indicated that the PANI shell was carbonized at 900°C. Platinum (Pt) nanoparticles were reduced by formic acid with catalyst supports. Compared to the untreated CNF/PANI composites, the carbonized composites were proven to be better supporting materials for the Pt nanocatalysts and showed superior performance as catalyst supports for methanol electrochemical oxidation. The current density of methanol oxidation on the catalyst with the core/shell nanostructured carbon materials is approximately seven times of that on the catalyst with CNF/PANI support. TEM tomography revealed that some Pt nanoparticles were embedded in the PANI shells of the CNF/PANI composites, which might decrease the electrocatalyst activity. TEM-energy dispersive spectroscopy mapping confirmed that the Pt nanoparticles in the inner tube of N-doped hollow CNFs could be accessed by the Nafion ionomer electrolyte, contributing to the catalytic oxidation of methanol.

  2. COx-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

    Siang-Piao Chai; Sharif Hussein Sharif Zein; Abdul Rahman Mohamed

    2006-01-01

    Direct decomposition of methane was carried out using a fixed-bed reactor at 700 ℃ for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2catalysts (where M=AgO, CoO, CuO, FeO, MnOx and MoO) in methane decomposition was investigated.The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiO2 support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2(w/w) since the highest yield of hydrogen was obtained over this catalyst.

  3. PdCo alloy nanoparticle-embedded carbon nanofiber for ultrasensitive nonenzymatic detection of hydrogen peroxide and nitrite.

    Liu, Dong; Guo, Qiaohui; Zhang, Xueping; Hou, Haoqing; You, Tianyan

    2015-07-15

    PdCo alloy nanoparticle-embedded carbon nanofiber (PdCo/CNF) prepared by electrospinning and thermal treatment was employed as a high-performance platform for the determination of hydrogen peroxide and nitrite. The as-obtained PdCo/CNF were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were employed to investigate the electrochemical behaviors of the resultant biosensor. The proposed PdCo/CNF-based biosensor showed excellent analytical performances toward hydrogen peroxide (detection limit: 0.1 μM; linear range: 0.2 μM-23.5 mM) and nitrite (detection limit: 0.2 μM; linear range: 0.4-30 μM and 30-400 μM). The superior analytical properties could be attributed to the synergic effect and firmly embedment of well-dispersed PdCo alloy nanoparticles. These attractive electrochemical properties make this robust electrode material promising for the development of effective electrochemical sensors. PMID:25818356

  4. The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

    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

  5. Ultrasensitive Bisphenol A Field-Effect Transistor Sensor Using an Aptamer-Modified Multichannel Carbon Nanofiber Transducer.

    Kim, Sung Gun; Lee, Jun Seop; Jun, Jaemoon; Shin, Dong Hoon; Jang, Jyongsik

    2016-03-16

    Bisphenol A (BPA) is a known endocrine-disrupting compound (EDC) that has a structure similar to that of the hormone estrogen. Even low concentrations of BPA are able to bind estrogen receptors, thereby inducing severe diseases such as reproductive disorders, chronic diseases, and various types of cancer. Despite such serious effects, the use of BPA remains widespread. Therefore, monitoring of both dietary and nondietary exposure to BPA is important for human healthcare. Herein, we present a field-effect transistor (FET) sensor using aptamer-modified multichannel carbon nanofibers (MCNFs) to detect BPA. The MCNFs are fabricated via single-nozzle electrospinning of two immiscible polymer solutions followed by thermal treatment in an inert atmosphere. The MCNFs are then oxidized using a solution of HNO3 and H2SO4 to introduce carboxyl groups on the surface of the fibers. The carboxyl-functionalized MCNFs (CMCNFs) are immobilized on an amine-functionalized electrode substrate by forming a covalent bond, and amine-functionalized BPA-binding aptamers are modified in the same manner on the CMCNFs. The resulting FET sensors exhibit a high sensitivity, as well as specificity toward BPA at an unprecedentedly low concentration of 1 fM. Furthermore, these sensors are stable and could be reused for repeated assays. PMID:26883578

  6. Arrays of nanofibers composed of a TiC core and a carbon coating for sensitive electrochemical detection of hydrazine

    Arrays made from quasi-aligned nanofibers consisting of a TiC/C composite were produced directly on a titanium alloy substrate by a thermochemical process. Their morphology, structure and composition were characterized by electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The arrays were directly utilized as an electrode without further treatment and display high catalytic activity in terms of hydrazine oxidation. The low overpotential decreases gradually when increasing pH values from 5 to 10. The detection range is linear from 0.1 to 1,635 μM concentrations, and the detection limit is as low as 0.026 μM (S/N=3). The selectivity of the electrode and its general performance and stability are very good. The improved electrochemical properties of the new electrode are attributed to the synergic effect of the highly conducting TiC nanowire core and an abundant amount of edge-plane-like defects on the carbon shells. (author)

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

    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.

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

    Ryan Pearce

    2014-04-01

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

  9. Preparation and electrochemical properties of RuO2-containing activated carbon nanofiber composites with hollow cores

    RuO2-containing activated carbon nanofibers with hollow cores (PMRu-ACNFs) are prepared through one-step electrospinning using polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), and ruthenium(III) acetylacetonate followed by thermal treatment. The porous PMRu-ACNF composites exhibit an improved morphological structure and textual properties due to the increased surface area, unique nanotexture, and presence of several functional groups such RuO2 in the ACNFs. Electrochemical measurements of PMRu-ACNF reveal a maximum specific capacitance of 180 Fg−1 and high energy densities of 20-14 Whkg−1 in the power density range of 400 to 10,000 W kg−1 in aqueous KOH electrolyte. In contrast, the ACNF electrodes show a lower specific capacitance and the energy density rapidly drops to 2 Whkg−1 at power densities of 4,000 Wkg−1. Therefore, the PMRu-ACNF composite electrodes may be more suitable as supercapacitors than regular ACNFs are, due to the synergistic effect between the electric double-layer capacitance of porous ACNFs and the pseudocapacitance of RuO2

  10. Co-production of hydrogen and carbon nanofibers from methane decomposition over zeolite Y supported Ni catalysts

    Highlights: • Methane cracking requires an optimum temperature range of 550–600 °C for H2 yield. • At 550 and 600 °C, catalyst showed longer activity for the whole test. • At 600 °C, a 614.25 gc/gNi of carbon was obtained using 30% Ni/Y zeolite catalysts. • Produced filamentous carbon has the same diameter as the metallic nickel itself. • VHSV has reverse and non-linear relevancy to the weight of Ni/Y zeolite catalyst. - Abstract: The objective of this paper is to study the influences of different operating conditions on the hydrogen formation and properties of accumulated carbon from methane decomposition using zeolite Y supported 15% and 30% Ni, respectively, at a temperature range between 500 and 650 °C in a pilot scale fixed bed reactor. The temperature ramp was showed a significant impact on the thermo-catalytic decomposition (TCD) of methane. An optimum temperature range of 550–600 °C were required to attain the maximum amount of methane conversion and revealed that at 550 and 600 °C, catalyst showed longer activity for the whole studied of experimental runs. Additionally, at 550 °C, the methane decomposition is two times longer for 30% Ni/Y zeolite than that for 15% Ni/Y zeolite catalyst, whereas it is almost three times higher at 500 °C. A maximum carbon yield of 614.25 and 157.54 gc/gNi were reported after end of the complete reaction at 600 °C with 30% and 15% Ni/Y zeolite catalyst, respectively. From BET, TPD, and XRD analysis, we had reported that how the chemistry between the TCD of methane and metal content of the catalysts could significantly affect the hydrogen production as well as carbon nano-fibers. TEM analysis ensured that the produced carbon had fishbone type structures with a hollow core and grew from crystallites of Ni anchored on the external surface of the catalysts and irrespective of the metal loadings, the whisker types of nano filaments were formed as confirmed from FESEM analysis. Nevertheless, the effect of

  11. Porous Core-Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction.

    Ren, Guangyuan; Lu, Xianyong; Li, Yunan; Zhu, Ying; Dai, Liming; Jiang, Lei

    2016-02-17

    The development of nonprecious-metal-based electrocatalysts with high oxygen reduction reaction (ORR) activity, low cost, and good durability in both alkaline and acidic media is very important for application of full cells. Herein, we developed a facile and economical strategy to obtain porous core-shell Fe3C embedded nitrogen-doped carbon nanofibers (Fe3C@NCNF-X, where X denotes pyrolysis temperature) by electrospinning of polyvinylidene fluoride (PVDF) and FeCl3 mixture, chemical vapor phase polymerization of pyrrole, and followed by pyrolysis of composite nanofibers at high temperatures. Note that the FeCl3 and polypyrrole acts as precursor for Fe3C core and N-doped carbon shell, respectively. Moreover, PVDF not only plays a role as carbon resources, but also provides porous structures due to hydrogen fluoride exposure originated from thermal decomposition of PVDF. The resultant Fe3C@NCNF-X catalysts, particularly Fe3C@NCNF-900, showed efficient electrocatalytic performance for ORR in both alkaline and acidic solutions, which are attributed to the synergistic effect between Fe3C and N-doped carbon as catalytic active sites, and carbon shell protects Fe3C from leaching out. In addition, the Fe3C@NCNF-X catalyst displayed a better long-term stability, free from methanol crossover and CO-poisoning effects than those of Pt/C, which is of great significance for the design and development of advanced electrocatalysts based on nonprecious metals. PMID:26808226

  12. Photoelectrochemical properties of hierarchical nanocomposite structure: Carbon nanofibers/TiO.sub.2./sub./ZnO thin films

    Kment, Štěpán; Hubička, Zdeněk; Kmentová, Hana; Klusoň, Petr; Krýsa, Josef; Gregora, Ivan; Morozová, Magdalena; Čada, Martin; Petráš, D.; Dytrych, Pavel; Slater, M.; Jastrabík, Lubomír

    2011-01-01

    Roč. 161, č. 1 (2011), s. 8-14. ISSN 0920-5861 R&D Projects: GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002; GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z40720504 Keywords : thin layers * hollow cathode * TiO 2 * ZnO * CNFs * IPCE * photocatalysis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.407, year: 2011

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

    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)

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

    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.

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

    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 detrimental ef...

  16. Competitive sorption of Pb(II), Cu(II) and Ni(II) on carbonaceous nanofibers: A spectroscopic and modeling approach.

    Ding, Congcong; Cheng, Wencai; Wang, Xiangxue; Wu, Zhen-Yu; Sun, Yubing; Chen, Changlun; Wang, Xiangke; Yu, Shu-Hong

    2016-08-01

    The competitive sorption of Pb(II), Cu(II) and Ni(II) on the uniform carbonaceous nanofibers (CNFs) was investigated in binary/ternary-metal systems. The pH-dependent sorption of Pb(II), Cu(II) and Ni(II) on CNFs was independent of ionic strength, indicating that inner-sphere surface complexation dominated sorption Pb(II), Cu(II) and Ni(II) on CNFs. The maximum sorption capacities of Pb(II), Cu(II) and Ni(II) on CNFs in single-metal systems at a pH 5.5±0.2 and 25±1°C were 3.84 (795.65mg/g), 3.21 (204.00mg/g) and 2.67 (156.70mg/g)mmol/g, respectively. In equimolar binary/ternary-metal systems, Pb(II) exhibited greater inhibition of the sorption of Cu(II) and Ni(II), demonstrating the stronger affinity of CNFs for Pb(II). The competitive sorption of heavy metals in ternary-metal systems was predicted quite well by surface complexation modeling derived from single-metal data. According to FTIR, XPS and EXAFS analyses, Pb(II), Cu(II) and Ni(II) were specifically adsorbed on CNFs via covalent bonding. These observations should provide an essential start in simultaneous removal of multiple heavy metals from aquatic environments by CNFs, and open the doorways for the application of CNFs. PMID:27108273

  17. Position-restricted growth of carbon nanofiber wiring between needle-shaped carbon pairs and various shaped carbons by Ar-ion laser-irradiated thermal decomposition in ethanol

    Carbon nanofiber (CNF) wiring between one pair of needle-shaped carbons (NSCs) and spherical-shaped carbons (SSCs) has been synthesized at a position-restricted area using an Ar-ion laser-irradiated thermal decomposition method in ethanol. We attempted to determine the optimal conditions with regard to several parameters, e.g. wavelength, laser-irradiation time and laser power density. The wavelength of 488 nm is suitable for synthesis of CNF wiring between one pair of NSCs. The NSC and SSC density increased up to 2.2 kW/cm2 with increases in the laser power density. When the redundant laser power density was irradiated on the Si substrate, CNF-wired NSCs and SSCs were synthesized in a laser-irradiated area for 2 min.

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

    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 (α) were calculated with the result as n = 4, α = 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 μM 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

  19. Electrospinning of ceramic nanofibers

    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

  20. Synthesis of SnO2versus Sn crystals within N-doped porous carbon nanofibers via electrospinning towards high-performance lithium ion batteries

    Wang, Hongkang; Lu, Xuan; Li, Longchao; Li, Beibei; Cao, Daxian; Wu, Qizhen; Li, Zhihui; Yang, Guang; Guo, Baolin; Niu, Chunming

    2016-03-01

    The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent characteristics. Herein, particulate SnO2 or Sn crystals coupled with porous N-doped carbon nanofibers (denoted as SnO2/PCNFs and Sn/PCNFs, respectively) are fabricated via the electrospinning method. The electrochemical behaviors of both SnO2/PCNFs and Sn/PCNFs are systematically investigated as anodes for LIBs. When coupled with porous carbon nanofibers, both SnO2 nanoparticles and Sn micro/nanoparticles display superior cycling and rate performances. SnO2/PCNFs and Sn/PCNFs deliver discharge capacities of 998 and 710 mA h g-1 after 140 cycles (at 100, 200, 500 and 1000 mA g-1 each for 10 cycles and then 100 cycles at 100 mA g-1), respectively. However, the Sn/PCNF electrodes show better cycling stability at higher current densities, delivering higher discharge capacities of 700 and 550 mA h g-1 than that of SnO2/PCNFs (685 and 424 mA h g-1) after 160 cycles at 200 and 500 mA g-1, respectively. The different superior electrochemical performance is attributed to the introduction of porous N-doped carbon nanofibers and their self-constructed networks, which, on the one hand, greatly decrease the charge-transfer resistance due to the high conductivity of N-doped carbon fibers; on the other hand, the porous carbon nanofibers with numerous voids and flexible one-dimensional (1D) structures efficiently alleviate the volume changes of SnO2 and Sn during the Li-Sn alloying-dealloying processes. Moreover, the discussion of the electrochemical behaviors of SnO2vs. Sn would provide new insights into the design of tin-based anode materials for practical applications, and the current strategy demonstrates great potential in the rational design of metallic tin-based anode materials.The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent

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

    Abild-Pedersen, Frank; Nørskov, Jens Kehlet; Rostrup-Nielsen, Jens;

    2006-01-01

    Mechanisms and energetics of graphene growth catalyzed by nickel nanoclusters were studied using ab initio density functional theory calculations. It is demonstrated that nickel step-edge sites act as the preferential growth centers for graphene layers on the nickel surface. Carbon is transported...

  2. The production of carbon nanofibers and thin films on palladium catalysts from ethylene oxygen mixtures

    Phillips, Jonathan [Los Alamos National Laboratory; Doorn, Stephen [Los Alamos National Laboratory; Atwater, Mark [UNM MECH.ENG.; Leseman, Zayd [UNM MECH.ENG.; Luhrs, Claudia C [UNM ENG.MECH; Diez, Yolanda F [SPAIN; Diaz, Angel M [SPAIN

    2009-01-01

    The characteristics of carbonaceous materials deposited in fuel rich ethylene-oxygen mixtures on three types of palladium: foil, sputtered film, and nanopowder, are reported. It was found that the form of palladium has a dramatic influence on the morphology of the deposited carbon. In particular, on sputtered film and powder, tight 'weaves' of sub-micron filaments formed quickly. In contrast, on foils under identical conditions, the dominant morphology is carbon thin films with basal planes oriented parallel to the substrate surface. Temperature, gas flow rate, reactant flow ratio (C2H4:02), and residence time (position) were found to influence both growth rate and type for all three forms of Pd. X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed oxidation, and Raman spectroscopy were used to assess the crystallinity of the as-deposited carbon, and it was determined that transmission electron microscopy and x-ray diffraction were the most reliable methods for determining crystallinity. The dependence of growth on reactor position, and the fact that no growth was observed in the absence of oxygen support the postulate that the carbon deposition proceeds by combustion generated radical species.

  3. Effect of thermal treatment on the properties of electrospun LiFePO4–carbon nanofiber composite cathode materials for lithium-ion batteries

    Graphical abstract: The composites prepared with the thermal treatment process of stabilization at 280 °C for 4 h with a heating rate of 2 °C min−1 in air followed by carbonization at 800 °C for 14 h with a heating rate of 2 °C min−1 in argon exhibit the optimal electrochemical properties. - Highlights: • Binder-free LiFePO4–CNF composite cathode materials are prepared. • The conductive carbon and LiFePO4 formation take place simultaneously during thermal treatment. • The reaction behavior of the LiFePO4 precursors during thermal treatment are investigated. • Different thermal treatment processes would generate different electrochemical performance. • Cycling performance and rate capability are improved with a suitable thermal treatment condition. - Abstract: Binder-free LiFePO4–carbon nanofiber (LiFePO4–CNF) composites as lithium-ion battery cathode materials are fabricated by electrospinning and subsequent thermal treatments. The thermal decomposition behavior of the electrospun LiFePO4 precursor–polyacrylonitrile (LiFePO4 precursor–PAN) nanofiber composites and the reaction of the LiFePO4 precursors during thermal treatment are investigated. The effects of thermal treatment parameters such as heating rate, temperature, and duration for stabilization and carbonization on the microstructure, morphology, carbon content, crystal structure of the composites, and electrochemical performance of the resultant half-cell are also studied. When the electrospun LiFePO4 precursor–PAN nanofiber composites are first stabilized in air at 280 °C for 4 h with a heating rate of 2 °C min−1 and then carbonized in argon at 800 °C for 14 h with a heating rate of 2 °C min−1, the obtained LiFePO4–CNF composites exhibit optimal electrochemical properties in terms of a higher initial discharge capacity, more stable charge–discharge cycle behavior, and better rate performance. The initial discharge capacity of the composites is 146.3 mA h g−1 at

  4. Cellulose Nanofibers as a Modifier for Rheology, Curing and Mechanical Performance of Oil Well Cement

    Sun, Xiuxuan; Wu, Qinglin; Lee, Sunyoung; Qing, Yan; Wu, Yiqiang

    2016-01-01

    The influence of nanocellulose on oil well cement (OWC) properties is not known in detail, despite recent advances in nanocellulose technology and its related composite materials. The effect of cellulose nanofibers (CNFs) on flow, hydration, morphology, and strength of OWC was investigated using a range of spectroscopic methods coupled with rheological modelling and strength analysis. The Vom-Berg model showed the best fitting result of the rheology data. The addition of CNFs increased the yield stress of OWC slurry and degree of hydration value of hydrated CNF-OWC composites. The flexural strength of hydrated OWC samples was increased by 20.7% at the CNF/OWC ratio of 0.04 wt%. Excessive addition of CNFs into OWC matrix had a detrimental effect on the mechanical properties of hydrated CNF-OWC composites. This phenomenon was attributed to the aggregation of CNFs as observed through coupled morphological and elemental analysis. This study demonstrates a sustainable reinforcing nano-material for use in cement-based formulations. PMID:27526784

  5. Cellulose Nanofibers as a Modifier for Rheology, Curing and Mechanical Performance of Oil Well Cement.

    Sun, Xiuxuan; Wu, Qinglin; Lee, Sunyoung; Qing, Yan; Wu, Yiqiang

    2016-01-01

    The influence of nanocellulose on oil well cement (OWC) properties is not known in detail, despite recent advances in nanocellulose technology and its related composite materials. The effect of cellulose nanofibers (CNFs) on flow, hydration, morphology, and strength of OWC was investigated using a range of spectroscopic methods coupled with rheological modelling and strength analysis. The Vom-Berg model showed the best fitting result of the rheology data. The addition of CNFs increased the yield stress of OWC slurry and degree of hydration value of hydrated CNF-OWC composites. The flexural strength of hydrated OWC samples was increased by 20.7% at the CNF/OWC ratio of 0.04 wt%. Excessive addition of CNFs into OWC matrix had a detrimental effect on the mechanical properties of hydrated CNF-OWC composites. This phenomenon was attributed to the aggregation of CNFs as observed through coupled morphological and elemental analysis. This study demonstrates a sustainable reinforcing nano-material for use in cement-based formulations. PMID:27526784

  6. The Cellulose Nanofibers for Optoelectronic Conversion and Energy Storage

    Yongfeng Luo

    2014-01-01

    Full Text Available Cellulose widely exists in plant tissues. Due to the large pores between the cellulose units, the regular paper is nontransparent that cannot be used in the optoelectronic devices. But some chemical and physical methods such as 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO oxidation can be used to improve the pores scale between the cellulose units to reach nanometer level. The cellulose nanofibers (CNFs have good mechanical strength, flexibility, thermostability, and low thermal expansion. The paper made of these nanofibers represent a kind of novel nanostructured material with ultrahigh transparency, ultrahigh haze, conductivity, biodegradable, reproducible, low pollution, environment friendly and so on. These advantages make the novel nanostructured paper apply in the optoelectronic device possible, such as electronics energy storage devices. This kind of paper is considered most likely to replace traditional materials like plastics and glass, which is attracting widespread attention, and the related research has also been reported. The purpose of this paper is to review CNFs which are applied in optoelectronic conversion and energy storage.

  7. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion.

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E; Liu, Tianxi

    2016-01-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications. PMID:27511271

  8. Synthesis and Electrochemical Characterization of Li2FeSiO4/Carbon Nanofiber Composite Cathode Material for Li Ion Batteries

    Kumar, Ajay; Nazri, Gholam Abbas; Naik, Ratna; Naik, Vaman M.

    2014-03-01

    Lithium transition metal silicates (Li2MSiO4) , where, M =Ni, Mn, Fe, and Co with a theoretical capacity of ~ 330 mAh/g have attracted great interest as possible replacements for cathode material in rechargeable batteries. However, this class of materials exhibit very low electronic conductivity and low lithium diffusivity. In order to enhance the electronic conductivity and reduce the diffusion length for lithium ion, we have synthesized Li2FeSiO4/carbon nanofiber (15 % wt) composites by sol-gel method. The composite materials were characterized by x-ray diffraction and scanning electron microscopy. The XRD data confirmed the formation of Li2FeSiO4 crystallites with size ~ 25 nm for composites annealed at 600 °C under argon atmosphere. The composite material was used as positive electrode in a coin cell configuration and the cells were characterized by AC impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge cycling. The cells showed a discharge capacity of ~ 230 mAh/g in the initial cycles, which suggests that more than one Li ion is extracted from the electrode. The effect of annealing at higher temperature on the electrochemical performance of Li2FeSiO4/carbon nanofiber composites will be presented.

  9. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E; Liu, Tianxi

    2016-01-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications. PMID:27511271

  10. Growth mechanisms of carbon nanotrees with branched carbon nanofibers synthesized by plasma-enhanced chemical vapour deposition

    He, Zhanbing; Maurice, Jean-Luc; Lee, Chang Seok; Cojocaru, Costel Sorin; Pribat, D.

    2014-01-01

    Y- and comb-type carbon nanotrees formed from branched carbon nanofibres grown by plasma-enhanced chemical vapour deposition were studied by transmission electron microscopy. Different growth mechanisms are proposed for the two types of nanotrees based on the observed and reconstituted dynamic transformations of the catalyst particles during synthesis. However, the splitting of the larger catalyst particles is required for both kinds of nanotrees, whatever the involved growth mechanism. The c...

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

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

    2013-01-01

    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....

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

    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

  13. High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst

    Yoshiyuki Suda

    2015-01-01

    Full Text Available Carbon nanocoil (CNC, which is synthesized by a catalytic chemical vapor deposition (CCVD method, has a coil diameter of 300–900 nm and a length of several tens of μm. Although it is very small, CNC is predicted to have a high mechanical strength and hence is expected to have a use in nanodevices such as electromagnetic wave absorbers and field emitters. For nanodevice applications, it is necessary to synthesize CNC in high yield and purity. In this study, we improved the conditions of catalytic layer formation and CCVD. Using optimized CVD conditions, a CNC layer with a thickness of >40 μm was grown from a SnO2/Fe2O3/SnO2 catalyst on a substrate, and its purity increased to 81% ± 2%.

  14. Effects of pore structure on the high-performance capacitive deionization using chemically activated carbon nanofibers.

    Im, Ji Sun; Kim, Jong Gu; Lee, Young-Seak

    2014-03-01

    Capacitive deionization (CDI) electrodes were constructed from activated carbon fibers prepared using electrospinning and chemical activation. The CDI efficiencies of these electrodes were studied as a function of their specific surface areas, pore volumes and pore sizes via salt ion adsorption. The specific surface areas increased approximately 90 fold and the pore volume also increased approximately 26 fold with the use of greater amounts of the chemical activation agent. There was a relative increase in the mesopore fraction with higher porosity. A NaCI solution was passed through a prepared CDI system, and the salt removal efficiency of the CDI system was determined by the separation of the Na+ and Cl- ions toward the anode and cathode. The CDI efficiency increased with greater specific surface areas and pore volumes. In addition, the efficiency per unit pore volume increased with a reduction in the micropore fraction, resulting in the suppressed overlapping effect. In conclusion, the obtained improvements in CDI efficiency were mainly attributed to mesopores, but the micropores also played an important role in the high-performance CDI under conditions of high applied potential and high ion concentrations. PMID:24745222

  15. Biomass-Derived Nitrogen-Doped Carbon Nanofiber Network: A Facile Template for Decoration of Ultrathin Nickel-Cobalt Layered Double Hydroxide Nanosheets as High-Performance Asymmetric Supercapacitor Electrode.

    Lai, Feili; Miao, Yue-E; Zuo, Lizeng; Lu, Hengyi; Huang, Yunpeng; Liu, Tianxi

    2016-06-01

    The development of biomass-based energy storage devices is an emerging trend to reduce the ever-increasing consumption of non-renewable resources. Here, nitrogen-doped carbonized bacterial cellulose (CBC-N) nanofibers are obtained by one-step carbonization of polyaniline coated bacterial cellulose (BC) nanofibers, which not only display excellent capacitive performance as the supercapacitor electrode, but also act as 3D bio-template for further deposition of ultrathin nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets. The as-obtained CBC-N@LDH composite electrodes exhibit significantly enhanced specific capacitance (1949.5 F g(-1) at a discharge current density of 1 A g(-1) , based on active materials), high capacitance retention of 54.7% even at a high discharge current density of 10 A g(-1) and excellent cycling stability of 74.4% retention after 5000 cycles. Furthermore, asymmetric supercapacitors (ASCs) are constructed using CBC-N@LDH composites as positive electrode materials and CBC-N nanofibers as negative electrode materials. By virtue of the intrinsic pseudocapacitive characteristics of CBC-N@LDH composites and 3D nitrogen-doped carbon nanofiber networks, the developed ASC exhibits high energy density of 36.3 Wh kg(-1) at the power density of 800.2 W kg(-1) . Therefore, this work presents a novel protocol for the large-scale production of biomass-derived high-performance electrode materials in practical supercapacitor applications. PMID:27135301

  16. Transparent bionanocomposite films based on chitosan and TEMPO-oxidized cellulose nanofibers with enhanced mechanical and barrier properties.

    Soni, Bhawna; Hassan, El Barbary; Schilling, M Wes; Mahmoud, Barakat

    2016-10-20

    The development of biobased active films for use in food packaging is increasing due to low cost, environmental appeal, renewability and availability. The objective of this research was to develop an effective and complete green approach for the production of bionanocomposite films with enhanced mechanical and barrier properties. This was accomplished by incorporating TEMPO-oxidized cellulose nanofibers (2,2,6,6-tetramethylpiperidine-1-oxyl radical) into a chitosan matrix. An aqueous suspension of chitosan (100-75wt%), sorbitol (25wt%) and TEMPO-oxidized cellulose nanofibers (TEMPO-CNFs, 0-25wt%) were cast in an oven at 40°C for 2-4days. Films were preconditioned at 25°C and 50% RH for characterization. The surface morphology of the films was revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermal properties and crystal structure of the films were evaluated by thermogravimetric analysis (TGA-DTG) and X-ray diffraction (XRD). Incorporation of TEMPO-CNFs enhanced the mechanical strength of the films due to the high aspect ratio (3-20nm width, and 10-100nm length) of TEMPO-CNFs and strong interactions with the chitosan matrix. Oxygen and water vapor transmission rates for films that are prepared with chitosan and TEMPO-CNFs (15-25wt%) were significantly reduced. Furthermore, these bionanocomposite films had good thermal stability. Use of TEMPO-CNFs in this method makes it possible to produce bionanocomposite films that are flexible, transparent, and thus have potential in food packaging applications. PMID:27474625

  17. Optimized CeO2 content of the carbon nanofiber support of PtRu catalyst for direct methanol fuel cells

    Kunitomo, Hikari; Ishitobi, Hirokazu; Nakagawa, Nobuyoshi

    2015-11-01

    A series of CeO2 embedded carbon nanofibers, CECNFs, with different CeO2 contents was prepared by an electrospinning technique. About 15 wt% PtRu nanoparticles were deposited on the fibers, and the effect of the CeO2 content on the methanol oxidation activity of the catalyst, PtRu/CECNF, was investigated. Cyclic voltammetry (CV), chronoamperometry (CA) and CO stripping electrochemical measurements and physical characterization along with X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were carried out on the prepared catalysts. The mass activity of the PtRu was significantly increased by the CeO2 addition up to Ce/C = 0.4, and the maximized activity was 2 times higher than that without CeO2. The increased activity was attributed to the strong interaction between the metal and oxide in the embedded nanofiber structure. A DMFC with the PtRu/CECNF exhibited more than 2.5 times high power density with one half the PtRu loading compared to that of the commercial catalyst, PtRu/Ccom.

  18. Rheological and physical properties of gelatin suspensions containing cellulose nanofibers for potential coatings.

    Andrade, Ricardo D; Skurtys, Olivier; Osorio, Fernando; Zuluaga, Robin; Gañán, Piedad; Castro, Cristina

    2015-07-01

    Rheological and physical properties of edible coating formulations containing gelatin, cellulose nanofibers (CNFs), and glycerol are characterized. Measured properties are analyzed in order to optimize edible coating thickness. Results show that coating formulations density increases linearly with gelatin concentration in presence of CNFs. Surface tension decreases with either gelatin or CNF concentration increases. Power law model well described the rheological behavior of edible coating formulations since determination coefficient was high (R(2 )> 0.98) and standard error was low (SE < 0.0052). Formulations showed pseudoplastic (shear-thinning) flow behavior and no time-dependent features were observed. The flow behavior index was not significantly affected by any factor. Consistency coefficient increases with gelatin concentrations but it decreases with glycerol concentrations. PMID:24831643

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

    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 μm 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

  20. Elastic and hierarchical porous carbon nanofibrous membranes incorporated with NiFe2O4 nanocrystals for highly efficient capacitive energy storage

    Ge, Jianlong; Fan, Gang; Si, Yang; He, Jianxin; Kim, Hak-Yong; Ding, Bin; Al-Deyab, Salem S.; El-Newehy, Mohamed; Yu, Jianyong

    2016-01-01

    Flexible membranes created from porous carbon nanofibers (CNFs) hold great promise in the next generation wearable energy storage devices, but challenges still remain due to the poor mechanical properties of porous carbon nanofibers. Here, we report a facile strategy to fabricate elastic and hierarchical porous CNF membranes with NiFe2O4 nanocrystals embedded via multicomponent electrospinning and nano-doping methods. Benefiting from the scattering effect of NiFe2O4 nanocrystals and graphitized carbon layers for the condensed stress, the resultant CNF membranes exhibit an enhanced elasticity with a bending radius Benefiting from the robust mechanical stability, hierarchical porous structures and good electrochemical properties, the NiFe2O4 doped CNF membranes demonstrate a high electrical capacitance of 343 F g-1, and good reversibility with a cycling efficiency of 97.4% even after 10 000 cycles. The successful synthesis of elastic porous CNF membranes also provided a versatile platform for the design and development of functional CNF based materials for various applications.Flexible membranes created from porous carbon nanofibers (CNFs) hold great promise in the next generation wearable energy storage devices, but challenges still remain due to the poor mechanical properties of porous carbon nanofibers. Here, we report a facile strategy to fabricate elastic and hierarchical porous CNF membranes with NiFe2O4 nanocrystals embedded via multicomponent electrospinning and nano-doping methods. Benefiting from the scattering effect of NiFe2O4 nanocrystals and graphitized carbon layers for the condensed stress, the resultant CNF membranes exhibit an enhanced elasticity with a bending radius Benefiting from the robust mechanical stability, hierarchical porous structures and good electrochemical properties, the NiFe2O4 doped CNF membranes demonstrate a high electrical capacitance of 343 F g-1, and good reversibility with a cycling efficiency of 97.4% even after 10 000

  1. Kinetics and deactivation mechanisms of the thermal decomposition of methane in hydrogen and carbon nanofiber Co-production over Ni-supported Y zeolite-based catalysts

    Highlights: • Methane cracking requires an optimum temperature range of 550–600 °C for H2 yield. • Reaction order and activation energy were 2.65 and 61.77 kJ/mol, respectively. • At 600 °C, a 496.40 gc/gNi of carbon was obtained using 30% Ni/Y zeolite catalysts. • Deactivation order and activation energy were 1.2, and 94.03 kJ/mol, respectively. • Produced filamentous carbon has the same diameter as the metallic nickel itself. - Abstract: This paper reports the reaction rate and deactivation kinetics of methane decomposition by using zeolite Y as the support and Ni as the active phase in a fixed bed reactor at a temperature range of 500 °C to 650 °C and at partial pressures of methane/nitrogen mixture of 0.2, 0.35, and 0.5 atm. The reaction order and activation energy were 2.65 and 61.77 kJ/mol, respectively. To quantify catalytic activity, carbon deposition rate was taken into consideration, which showed that the actual and thermodynamically predicted accumulated carbons were in good balance. Deactivation order, methane concentration dependency, and activation energy were 1.2, −1.28, and 94.03 kJ/mol, respectively. The kinetic experiment indicates that the optimum temperature range should be maintained to achieve the highest performance from 30% Ni/Y zeolite in terms of hydrogen formation rate, average hydrogen formation rate, total hydrogen formation, average carbon formation, total carbon formation, and carbon formation rate. TEM and XRD analysis were performed to characterize the deactivated, fresh, and calcined catalysts, and the results indicated that the formed filamentous carbon has the same diameter as the metallic nickel itself. The influence of volume hourly space velocity (VHSV) on methane conversion and carbon nanofiber production was also discussed

  2. In situ fabrication of three-dimensional nitrogen and boron co-doped porous carbon nanofibers for high performance lithium-ion batteries

    Zhang, Lijun; Xia, Guanglin; Guo, Zaiping; Sun, Dalin; Li, Xingguo; Yu, Xuebin

    2016-08-01

    This paper reports the fabrication of three-dimensional porous carbon nanofibers network with high doping level of nitrogen (N, 5.17 at.%) and boron (B, 6.87 at.%) through a general electrospinning strategy followed by a calcination process. The employed ammonia borane (NH3BH3, denote as AB) not only functions as a porogen reagent to generate porous structures but also as the heteroatoms source to induce N and B co-doping. Such highly unique nanoarchitectures offer remarkably improved Li storage performance including high reversible capacity (∼910 mAh g-1 at a current density of 100 mA g-1) with good cycling and rate performances.

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

    Susobhan Das

    2015-12-01

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

  4. Synthesis of carbon nanofibres from waste chicken fat for field electron emission applications

    Highlights: • Waste chicken fat is used as a starting material to produce CNFs via TCVD method. • High heating rate applied resulted in aggregation of catalyst particles. • Aggregated catalyst produced sea urchin-like CNFs with amorphous nature. • The as-grown CNFs presented a potential for field electron emission applications. - Abstract: Carbon nanofibres (CNFs) with sea urchin-like morphology were synthesised from waste chicken fat precursor via catalytic thermal chemical vapour deposition method at 750 °C. The CNFs showed amorphous structures under high-resolution transmission electron microscopy, micro-Raman spectroscopy and X-ray diffraction examination. X-ray photoelectron spectroscopy analysis confirmed that the core of the sea urchin-like CNFs was composed of Fe3C formed within the first 20 min of synthesis time. The growth of amorphous CNFs from agglomerated Fe3C particles was favourable due to the high heating rate applied during the synthesis. Field electron emission examination of the CNFs indicated turn-on and threshold field values of 5.4 and 6.6 V μm−1 at current density of 1 and 10 μA cm−2, respectively. This study demonstrates that waste chicken fat, a low-cost and readily available resource, can be used as an inexpensive carbon source for the production of CNFs with a potential application in field electron emitters

  5. Synthesis of carbon nanofibres from waste chicken fat for field electron emission applications

    Suriani, A.B., E-mail: absuriani@yahoo.com [Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Department of Physics, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Dalila, A.R. [Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Department of Physics, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Mohamed, A.; Isa, I.M.; Kamari, A.; Hashim, N. [Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim, Perak 35900 (Malaysia); Soga, T.; Tanemura, M. [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2015-10-15

    Highlights: • Waste chicken fat is used as a starting material to produce CNFs via TCVD method. • High heating rate applied resulted in aggregation of catalyst particles. • Aggregated catalyst produced sea urchin-like CNFs with amorphous nature. • The as-grown CNFs presented a potential for field electron emission applications. - Abstract: Carbon nanofibres (CNFs) with sea urchin-like morphology were synthesised from waste chicken fat precursor via catalytic thermal chemical vapour deposition method at 750 °C. The CNFs showed amorphous structures under high-resolution transmission electron microscopy, micro-Raman spectroscopy and X-ray diffraction examination. X-ray photoelectron spectroscopy analysis confirmed that the core of the sea urchin-like CNFs was composed of Fe{sub 3}C formed within the first 20 min of synthesis time. The growth of amorphous CNFs from agglomerated Fe{sub 3}C particles was favourable due to the high heating rate applied during the synthesis. Field electron emission examination of the CNFs indicated turn-on and threshold field values of 5.4 and 6.6 V μm{sup −1} at current density of 1 and 10 μA cm{sup −2}, respectively. This study demonstrates that waste chicken fat, a low-cost and readily available resource, can be used as an inexpensive carbon source for the production of CNFs with a potential application in field electron emitters.

  6. A simple one step organic to inorganic pyrolysis route to bulk quantity boron carbonitride/carbon nanocables

    Highlights: • Bulk quantity boron carbonitride/carbon (BCN/C) nanocables have been synthesized by a simple one step organic to inorganic pyrolysis route. • BCN/C nanocables exhibit a much better oxidation resistance than substrate carbon nanofibers. • A probable formation mechanism of the BCN/C nanocables is proposed according to the experimental results. - Abstract: Bulk quantity boron carbonitride/carbon (BCN/C) nanocables have been successfully synthesized by a simple one step organic compounds pyrolysis route at 1100 °C. The nanocables consist of nanocarbon fibers inside covered by the cylindrical BCN coatings. The characteristics of the surface morphology and the diameters of the nanocables are determined by soaking time. It is demonstrated that the elements of B, C and N are hybridly bonded in the coating. The weight loss of the nanocables is about 12% at 1200 °C which is much better than the substrate carbon nanofibers (CNFs) (more than 20% weight loss at 1200 °C). The minimum reflection coefficient below −20 dB for the products is −24.5 dB at 14.48 GHz indicating good microwave absorption properties. The results suggest that the nanocables are favorable for achieving high performance oxidization resistance and microwave absorption properties

  7. Effect of thermal treatment on the properties of electrospun LiFePO{sub 4}–carbon nanofiber composite cathode materials for lithium-ion batteries

    Zhang, Changhuan; Liang, Yinzheng; Yao, Lan; Qiu, Yiping, E-mail: ypqiu@dhu.edu.cn

    2015-04-05

    Graphical abstract: The composites prepared with the thermal treatment process of stabilization at 280 °C for 4 h with a heating rate of 2 °C min{sup −1} in air followed by carbonization at 800 °C for 14 h with a heating rate of 2 °C min{sup −1} in argon exhibit the optimal electrochemical properties. - Highlights: • Binder-free LiFePO{sub 4}–CNF composite cathode materials are prepared. • The conductive carbon and LiFePO{sub 4} formation take place simultaneously during thermal treatment. • The reaction behavior of the LiFePO{sub 4} precursors during thermal treatment are investigated. • Different thermal treatment processes would generate different electrochemical performance. • Cycling performance and rate capability are improved with a suitable thermal treatment condition. - Abstract: Binder-free LiFePO{sub 4}–carbon nanofiber (LiFePO{sub 4}–CNF) composites as lithium-ion battery cathode materials are fabricated by electrospinning and subsequent thermal treatments. The thermal decomposition behavior of the electrospun LiFePO{sub 4} precursor–polyacrylonitrile (LiFePO{sub 4} precursor–PAN) nanofiber composites and the reaction of the LiFePO{sub 4} precursors during thermal treatment are investigated. The effects of thermal treatment parameters such as heating rate, temperature, and duration for stabilization and carbonization on the microstructure, morphology, carbon content, crystal structure of the composites, and electrochemical performance of the resultant half-cell are also studied. When the electrospun LiFePO{sub 4} precursor–PAN nanofiber composites are first stabilized in air at 280 °C for 4 h with a heating rate of 2 °C min{sup −1} and then carbonized in argon at 800 °C for 14 h with a heating rate of 2 °C min{sup −1}, the obtained LiFePO{sub 4}–CNF composites exhibit optimal electrochemical properties in terms of a higher initial discharge capacity, more stable charge–discharge cycle behavior, and better rate

  8. On-chip microplasma reactors using carbon nanofibres and tungsten oxide nanowires as electrodes

    Agiral, Anil; Groenland, Alforns W.; Kumar Chinthaginjala, J.; Seshan, K.; Lefferts, Leon; Gardeniers, J.G.E. (Han)

    2008-01-01

    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 sc

  9. 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

    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.

  10. Application of a composite structure of carbon nanoparticles and Nb-TiO2 nanofibers as electrocatalyst support for PEM fuel cells

    Bauer, Alex; Hui, Rob; Ignaszak, Anna; Zhang, Jiujun; Jones, Deborah J.

    2012-07-01

    Platinum catalyst nanoparticles (20 wt.%) were deposited on a mixed support, which consisted of 25 at.% Nb doped TiO2 nanofibers and carbon agglomerates. XRD analysis revealed that titania was present in the rutile phase. The catalyst was characterized electrochemically with respect to durability and oxygen reduction activity. Based on cyclic voltammetry tests, the Nb-TiO2/C supported catalyst was more stable compared to a commercially available carbon supported Pt catalyst (E-tek) over 1000 cycles. The apparent active Pt area decreased by 5% due to cycling, whereas in the case of Pt/C the decrease was 23%. The oxygen reduction performance was comparable for both cases. For example, during the anodic sweep the mass activity at 0.9 V vs. the reversible hydrogen electrode (RHE) was 19 A gPt-1 and 20 A gPt-1 for the freshly prepared in-house prepared and commercial catalysts, respectively. After the durability experiment both types of catalysts yielded a mass activity of 17 A gPt-1. Fuel cell tests with a single cell configuration were also carried out with the Nb-TiO2/C supported catalyst on the cathode side (gas diffusion electrode), yielding a peak power density of 0.34 W cm-2 at 75 °C when pure oxygen was supplied on the cathode side.

  11. Improved reaction kinetics and selectivity by the TiO2-embedded carbon nanofiber support for electro-oxidation of ethanol on PtRu nanoparticles

    Nakagawa, Nobuyoshi; Ito, Yudai; Tsujiguchi, Takuya; Ishitobi, Hirokazu

    2014-02-01

    The electro-oxidation of ethanol by the catalyst of PtRu nanoparticles supported on a TiO2-embedded carbon nanofiber (PtRu/TECNF), which has recently been proposed by the authors as a highly active catalyst for methanol oxidation, is investigated by cyclic voltammetry using a glassy carbon electrode and by operating a direct ethanol fuel cell (DEFC) with the catalyst. The mass activity obtained from the cyclic voltammogram for the ethanol oxidation is compared to that for the methanol oxidation reported in our recent paper. The mass activity for the ethanol oxidation is comparable or slightly higher than that for the methanol oxidation, and the relationship between the TECNF composition, i.e., the Ti/C mass ratio, and the activity are also similar to that for the methanol oxidation. A DEFC fabricated with the PtRu/TECNF shows a higher power output compared to that with the commercial PtRu/C catalyst. An analysis of the reaction products by a simple two-step reaction model reveals that the PtRu/TECNF increases the rate constant for the reaction steps from ethanol to acetaldehyde and subsequently to CO2, but decreases that from acetaldehyde to acetic acid. This means that the PtRu/TECNF improves not only the kinetics, but also the selectivity to acetaldehyde.

  12. Preparation of a novel PAN/cellulose acetate-Ag based activated carbon nanofiber and its adsorption performance for low-concentration SO2

    Wu, Yan-bo; Bi, Jun; Lou, Ting; Song, Tie-ben; Yu, Hong-quan

    2015-04-01

    Polyacrylonitrile (PAN), PAN/cellulose acetate (CA), and PAN/CA-Ag based activated carbon nanofiber (ACNF) were prepared using electrostatic spinning and further heat treatment. Thermogravimetry-differential scanning calorimetry (TG-DSC) analysis indicated that the addition of CA or Ag did not have a significant impact on the thermal decomposition of PAN materials but the yields of fibers could be improved. Scanning electron microscopy (SEM) analysis showed that the micromorphologies of produced fibers were greatly influenced by the viscosity and conductivity of precursor solutions. Fourier transform infrared spectroscopy (FT-IR) analysis proved that a cyclized or trapezoidal structure could form and the carbon scaffold composed of C=C bonds appeared in the PAN-based ACNFs. The characteristic diffraction peaks in X-ray diffraction (XRD) spectra were the evidence of a turbostratic structure and silver existed in the PAN/CA-Ag based ACNF. Brunner-Emmett-Teller (BET) analysis showed that the doping of CA and Ag increased surface area and micropore volume of fibers; particularly, PAN/CA-Ag based ACNF exhibited the best porosity feature. Furthermore, SO2 adsorption experiments indicated that all the three fibers had good adsorption effects on lower concentrations of SO2 at room temperature; especially, the PAN/CA-Ag based ACNF showed the best adsorption performance, and it may be one of the most promising adsorbents used in the fields of chemical industry and environment protection.

  13. Mechanical properties of simultaneously synthesized and consolidated carbon nanofiber (CNF)-dispersed SiC composites by pulsed electric-current pressure sintering

    Carbon nanofiber (CNF) dispersed β-SiC composites with the addition of 0.2 mass% boron and 2.0 mass% carbon as sintering aids have been synthesized and consolidated simultaneously from mixtures of Si, amorphous C and B powders and CNF by pulsed electric-current pressure sintering (PECPS). Synthesis and consolidation process, which were observed from their expansion and shrinkage curves during PECPS, have been examined using X-ray diffraction and scanning electron microscopy for the powder compacts. CNF/SiC composites sintered at 1800 deg. C for 10 min under 40 MPa in a vacuum have ∼96.0% of theoretical density and homogeneous structures consisting of ∼4.0 μm grains. A 10 vol% CNF/SiC composite exhibited excellent mechanical properties: a bending strength of ∼720 MPa, a Vickers hardness of ∼26.0 GPa, and a fracture toughness of ∼5.5 MPa m1/2. High-temperature bending strength of ∼890 MPa at 1200 deg. C in air was attained with the same nanocomposites

  14. Graphite-nanoplatelet-decorated polymer nanofiber with improved thermal, electrical, and mechanical properties.

    Gao, Jiefeng; Hu, Mingjun; Dong, Yucheng; Li, Robert K Y

    2013-08-28

    Graphite-nanoplatelet (GNP)-decorated polymer nanofiber composites with hierarchical structures were fabricated by the combination of electrospinning and ultrasonication. It was found that GNPs could be well attached or embedded onto the nanofibers when their size was comparable to the nanofiber diameter. X-ray diffraction results indicated that ultrasonic treatment exerted no influence on the carbon crystal layer spacing. Fourier transform infrared spectra and Raman spectroscopy revealed the existence of interfacial interaction between GNPs and polyurethane nanofibers. The prepared nanofiber composite showed enhanced thermal stability and hardness, which originated from uniform dispersion of GNPs as well as strong interaction between GNPs and the nanofibers. The electrical conductivity was significantly improved, derived from the formation of a conductive percolation network in the nanofiber composite. During ultrasonication, cavitation bubbles may be formed in liquid, and microjets and shock waves were created near the GNP surface after collapse of the bubbles. These jets, causing sintering of GNPs, pushed GNPs toward the nanofiber surface at very high speeds. When the fast-moving GNPs hit the nanofiber surface, interfacial collision between GNPs and the nanofibers occurs, the nanofiber may experience partial softening or even melting at the impact sites, and then GNPs could be uniformly anchored onto the nanofibers. This method opens a new door for harvesting GNP-based nanofiber composites with improved material properties. PMID:23910565

  15. Electrospun nanofiber membranes for electrically activated shape memory nanocomposites

    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. (papers)

  16. Synthesis of carbon nanofibres from a liquid solution containing both catalyst and polyethylene glycol

    Carbon nanofibres (CNFs) exhibiting bamboo-like, hollow fibril morphology were prepared from a mixture of polyethylene glycol (PEG) and iron-based compounds such as Fe2(SO4)3·nH2O, Fe(NO3)·9H2O or FeO(OH) by a thermal process. These materials were well mixed in distilled water prior to thermal treatment in an air/nitrogen atmosphere. With increasing temperature, the mixture underwent solvent removal, dehydrogenation, thermal decomposition, carbonization and catalytic graphitization to form CNFs. Results show that CNFs can be formed with different PEG/catalyst ratios (100/1-1000/1 by weight) at 750 deg. C. The catalyst effect is discussed for the formation of bamboo-like CNFs. The diameter of the CNFs was about 30-50 nm while the length was a few micrometres

  17. Graphitised Carbon Nanofibres as Catalyst Support for PEMFC

    Yli-Rantala, E.; Pasanen, A.; Kauranen, P.;

    2011-01-01

    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......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...

  18. Effect of sulfonated carbon nanofiber-supported Pt on performance of Nafion {sup registered} -based self-humidifying composite membrane for proton exchange membrane fuel cell

    Hung, T.F. [Department of Chemistry and Center for Nanotechnology, Chung Yuan Christian University, 200 Chung Pei Rd., Chung-Li, 32023 (China); Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 (China); Liao, S.H.; Li, C.Y.; Chen-Yang, Y.W. [Department of Chemistry and Center for Nanotechnology, Chung Yuan Christian University, 200 Chung Pei Rd., Chung-Li, 32023 (China)

    2011-01-01

    In the present study, the Nafion {sup registered} -based self-humidifying composite membrane (N-SHCM) with sulfonated carbon nanofiber-supported Pt (s-Pt/CNF) catalyst, N-s-Pt/CNF, is successfully prepared using the solution-casting method. The scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) images of N-s-Pt/CNF indicate that s-Pt/CNF is well dispersed in the Nafion {sup registered} matrix due to the good compatibility between Nafion {sup registered} and s-Pt/CNF. Compared with those of the non-sulfonated Pt/CNF-containing N-SHCM, N-Pt/CNF, the properties of N-s-Pt/CNF, including electronic resistivity, ion-exchange capacity (IEC), water uptake, dimensional stability, and catalytic activity, significantly increase. The maximum power density of the proton exchange membrane fuel cell (PEMFC) fabricated with N-s-Pt/CNF operated at 50 C under dry H{sub 2}/O{sub 2} condition is about 921 mW cm{sup -2}, which is approximately 34% higher than that with N-Pt/CNF. (author)

  19. A new microplatform based on titanium dioxide nanofibers/graphene oxide nanosheets nanocomposite modified screen printed carbon electrode for electrochemical determination of adenine in the presence of guanine.

    Arvand, Majid; Ghodsi, Navid; Zanjanchi, Mohammad Ali

    2016-03-15

    The current techniques for determining adenine have several shortcomings such as high cost, high time consumption, tedious pretreatment steps and the requirements for highly skilled personnel often restrict their use in routine analytical practice. This paper describes the development and utilization of a new nanocomposite consisting of titanium dioxide nanofibers (TNFs) and graphene oxide nanosheets (GONs) for screen printed carbon electrode (SPCE) modification. The synthesized GONs and TNFs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The modified electrode (TNFs/GONs/SPCE) was used for electrochemical characterization of adenine. The TNFs/GONs/SPCE exhibited an increase in peak current and the electron transfer kinetics and decrease in the overpotential for the oxidation reaction of adenine. Using differential pulse voltammetry (DPV), the prepared sensor showed good sensitivity for determining adenine in two ranges from 0.1-1 and 1-10 μM, with a detection limit (DL) of 1.71 nM. Electrochemical studies suggested that the TNFs/GONs/SPCE provided a synergistic augmentation on the voltammetric behavior of electrochemical oxidation of adenine, which was indicated by the improvement of anodic peak current and a decrease in anodic peak potential. The amount of adenine in pBudCE4.1 plasmid was determined via the proposed sensor and the result was in good compatibility with the sequence data of pBudCE4.1 plasmid. PMID:26556182

  20. Amorphous Fe2O3 nanoshells coated on carbonized bacterial cellulose nanofibers as a flexible anode for high-performance lithium ion batteries

    Huang, Yang; Lin, Zixia; Zheng, Mingbo; Wang, Tianhe; Yang, Jiazhi; Yuan, Fanshu; Lu, Xiaoyu; Liu, Lin; Sun, Dongping

    2016-03-01

    A three-dimensional (3D) carbonaceous aerogel derived from biomass bacterial cellulose (BC) is introduced as a flexible framework for iron oxides in Li-ion batteries (LIBs). The 3D carbonized BC (CBC) with highly interconnected nanofibrous structure exhibits good electrical conductivity and mechanical stability. The amorphous Fe2O3 is tightly coated on the nanofibers of CBC through a simple in situ thermal decomposition method. The obtained amorphous Fe2O3 anode (denoted as A-Fe2O3@CBC) exhibits stable cycling performance and high rate capability when assembled into a half-cell, which is supposed to benefit from the well-dispersed Fe2O3 nanoshells and the hierarchical pores in A-Fe2O3@CBC composite. The rational design of the nanostructure could improve the transportation of electrons/ions and effectively alleviate volume changes of Fe2O3 during the electrochemical cycling. Meanwhile, the amorphous nature of the Fe2O3 in anode provides an enhanced capacitive-like lithium storage and flexible structure of the active materials, resulting in much higher specific capacity and longer cycle life when compared with its crystalline counterpart. This work provides a promising approach to design and construct the flexible metal oxide anode materials based on 3D carbonaceous aerogel for high-performance LIBs.

  1. Electrospinning Directly Synthesized Porous TiO2 Nanofibers Modified by Graphitic Carbon Nitride Sheets for Enhanced Photocatalytic Degradation Activity under Solar Light Irradiation.

    Adhikari, Surya Prasad; Awasthi, Ganesh Prasad; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2016-06-21

    We report a direct approach to the fabrication of a composite made of porous TiO2 nanofibers (NFs) and graphitic carbon nitride (g-C3N4) sheets, by means of an angled two-nozzle electrospinning combined with calcination process. Different wt % amounts of g-C3N4 particles in a polymer solution from one nozzle and TiO2 precursors containing the same polymer solution from another nozzle were electrospun and deposited on the collector. Structural characterizations confirm a well-defined morphology of the TiO2/g-C3N4 composite in which the TiO2 NFs are uniformly attached on the g-C3N4 sheet. This proper attachment of TiO2 NFs on the g-C3N4 sheets occurred during calcination. The prepared composites showed the enhanced photocatalytic activity over the photodegradation of rhodamine B and reactive black 5 under natural sunlight. Here, the synergistic effect between the g-C3N4 sheets and the TiO2 NFs having anisotropic properties enhanced the photogenerated electron-hole pair separation and migration, which was confirmed by the measurement of photoluminescence spectra, cyclic voltammograms, and electrochemical impedance spectra. The direct synthesis approach that is established here for such kinds of sheetlike structure and porous NFs composites could provide new insights for the design of high-performance energy conversion catalysts. PMID:27254544

  2. Recent Nanofiber Technologies

    Kim, Byoung-Suhk; Kim, Ick-Soo

    2011-01-01

    This article is a perspective that includes a brief introduction to nanofiber production methods, their potential applications, and three review articles in the field of nanofibers. Although the full range of applications that best exploit these new developments are yet to be developed, the emerging innovative applications of nanofibers in biomedical, sensor, electronic, and other areas will likely be enabled or enhanced by these recent advances in several key techniques. Three review article...

  3. NANOFIBER PRODUCTION [REVIEW

    KESKIN Reyhan

    2016-05-01

    Full Text Available Nanofibers are very thin fibers having diameters lower than 100 nm and their lengths might be as long as possible within production limits. The large surface area of nanofibers gives opportunity to functionalize them. Nanofibers have several applications including both applications for industrial production in many sectors and for research studies. Nanofibers find applications in energy devices such as solar cells, fuel cells and nanogenarators; in filtration applications (such as water/oil filtration, fine particle filtration, aerosol filtration, air filtration, nanoparticle filtration and in several medical applications including antibacterial efficacy, wound healing, drug delivery and scaffolds for tissue engineering. There are several methods to produce nanofibers: Electrospinning, self assembly, phase separation, bacterial cellulose, templating, drawing, extraction, vapor-phase polymerization, kinetically controlled solution synthesis, conventional chemical polymerization for anyline. Electrospinning is the most widely used method to produce nanofibers.In electrospinning, a high electric field, which is in kilovolts, is applied to a polymer solution. The polymer solution is drawn from a syringe to a collector surface.Electrospinning requires usage of appropriate solvent, removal of evaporating solvent, an adequate power supply to overcome the viscosity and surface tension of the polymer solution; while, jet instability and jet control remain as challenges in electrospinning. Nanofiber production methods possess some disadvantages as: higher cost compared to conventional fiber production methods, health hazards such as inhale risk of nanofibers during production and keeping the environment safe from evaporating solvents used during nanofiber production. Up to date, many researches have been conducted on nanofibers and electrospinning; still, more controllable, more cost effective, more environmentally friendly and safer methods are of

  4. Challenges and Benefits of Utilizing Carbon Nanofilaments in Cementitious Materials

    Ardavan Yazdanbakhsh

    2012-01-01

    Full Text Available Carbon nanofibers/tubes (CNF/Ts are very strong and stiff and as a result, are expected to be capable of enhancing the mechanical properties of cementitious materials significantly. Yet there are practical issues concerning the utilization of CNF/Ts in cementitious materials. This study summarizes some of the past efforts made by different investigators for utilizing carbon nanofilaments in cementitious materials and also reports recent experimental research performed by the authors on the mechanical properties of CNF-reinforced hardened cement paste. The major difficulties concerning the utilization of CNF/Ts in cementitious materials are introduced and discussed. Most of these difficulties are related to the poor dispersibility of CNF/Ts. However, the findings from the research presented in this work indicate that, despite these difficulties, carbon nanofilaments can significantly improve the mechanical properties of cementitious materials. The results show that CNFs, even when poorly dispersed within the cementitious matrix, can remarkably increase the flexural strength and cracking resistance of concrete subjected to drying conditions.

  5. Effects of Feed Gas Composition and Catalyst Thickness on Carbon Nanotube and Nanofiber Synthesis by Plasma Enhanced Chemical Vapor Deposition

    R K Garg; Kim, S. S.; Hash, D. B; Gore, Jay P.; Fisher, Timothy

    2008-01-01

    Many engineering applications require carbon nanotubes with specific characteristics such as wall structure, chirality and alignment. However, precise control of nanotube properties grown to application specifications remains a significant challenge. Plasma-enhanced chemical vapor deposition (PECVD) offers a variety of advantages in the synthesis of carbon nanotubes in that several important synthesis parameters can be controlled independently. This paper reports an experimental study of the ...

  6. Active bio-based food-packaging: Diffusion and release of active substances through and from cellulose nanofiber coating toward food-packaging design.

    Lavoine, Nathalie; Guillard, Valérie; Desloges, Isabelle; Gontard, Nathalie; Bras, Julien

    2016-09-20

    Cellulose nanofibers (CNFs) were recently investigated for the elaboration of new functional food-packaging materials. Their nanoporous network was especially of interest for controlling the release of active species. Qualitative release studies were conducted, but quantification of the diffusion phenomenon observed when the active species are released from and through CNF coating has not yet been studied. Therefore, this work aims to model CNF-coated paper substrates as controlled release system for food-packaging using release data obtained for two model molecules, namely caffeine and chlorhexidine digluconate. The applied mathematical model - derived from Fickian diffusion - was validated for caffeine only. When the active species chemically interacts with the release device, another model is required as a non-predominantly diffusion-controlled release was observed. From caffeine modeling data, a theoretical active food-packaging material was designed. The use of CNFs as barrier coating was proved to be the ideal material configuration that best meets specifications. PMID:27261728

  7. Electrospun lignin-derived carbon nanofiber mats surface-decorated with MnO2 nanowhiskers as binder-free supercapacitor electrodes with high performance

    Ma, Xiaojing; Kolla, Praveen; Zhao, Yong; Smirnova, Alevtina L.; Fong, Hao

    2016-09-01

    The aim of this study is to explore innovative materials for the development of next-generation supercapacitor electrodes. The hypothesis is that, upon the surface-decoration with appropriate amount of MnO2 nanowhiskers, freestanding and highly graphitic electrospun carbon nanofiber (ECNF) mats (with fiber diameters of ∼200 nm and BET specific surface areas of ∼583 m2 g-1) derived from a natural product of lignin would be binder-free supercapacitor electrodes with high performance. To test the hypothesis, the ECNF mats have been prepared first; thereafter, the acquired ECNF mats have been surface-decorated with varied amounts of MnO2 nanowhiskers to prepare three types of ECNF/MnO2 mats. The morphological and structural properties of ECNF and ECNF/MnO2 mats are characterized by SEM, TEM and XRD, the weight percentages of MnO2 nanowhiskers in three ECNF/MnO2 mats are determined by thermal gravimetric analysis; while the electrochemical performance of each mat/electrode is evaluated by cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy. This study reveals that, all of the three ECNF/MnO2 mats/electrodes have significantly enhanced electrochemical performances compared to the ECNF mat/electrode; while the ECNF/MnO2 (1:1) mat/electrode exhibits the highest gravimetric capacitance of 83.3 F g-1, energy density of 84.3 W h kg-1, and power density of 5.72 kW kg-1.

  8. Rippling of polymer nanofibers.

    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

  9. Electrospun Gallium Nitride Nanofibers

    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.

  10. Li1.2Mn0.54Ni0.13Co0.13O2-Encapsulated Carbon Nanofiber Network Cathodes with Improved Stability and Rate Capability for Li-ion Batteries

    Ma, Dingtao; Zhang, Peixin; Li, Yongliang; Ren, Xiangzhong

    2015-06-01

    Li1.2Mn0.54Ni0.13Co0.13O2-encapsulated carbon nanofiber network cathode materials were synthesized by a facile electrospinning method. The microstructures, morphologies and electrochemical properties are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), galvonostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS), etc. The nanofiber decorated Li1.2Mn0.54Ni0.13Co0.13O2 electrode demonstrated higher coulombic efficiency of 83.5%, and discharge capacity of 263.7 mAh g-1 at 1 C as well as higher stability compared to the pristine particle counterpart. The superior electrochemical performance results from the novel network structure which provides fast transport channels for electrons and lithium ions and the outer carbon acts a protection layer which prevents the inner oxides from reacting with HF in the electrolyte during charge-discharge cycling.

  11. Optics of Nanofibers

    Bordo, Vladimir

    During the last decade, fabrication and investigation of submicron-sized optical fibers have been received growing attention. Such nanofibers or nanowires can be grown from both inorganic and organic semiconductor materials being arranged in mutually parallel nanoaggregates. Also, selected...... necessity of fundamental understanding of underlying optical processes which occur in nanofibers. In the present talk, we give a brief overview of recent experimental results in this field. Different theoretical models which can be used for the description of waveguiding and light scattering in nanofibers...

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

    Baek Jong-Beom; Saeed Khalid; Park Soo-Young; Haider Sajjad

    2008-01-01

    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 matr...

  13. Fabrication and Experimental Analysis of Axially Oriented Nanofibers.

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

    2016-03-01

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

  14. Solution blow spinning: parameters optimization and effects on the properties of nanofibers from poly(lactic) acid/dimethyl carbonate solutions

    Solution blow spinning (SBS) is a process to produce non-woven fiber sheets with high porosity and an extremely large amount of surface area. In this study, a Box-Behnken experimental design (BBD) was used to optimize the processing parameters for the production of nanofibers from polymer solutions ...

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

    Javed Rafique; Jie Yu; Xiaoxiong Zha; Khalid Rafique

    2010-10-01

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

  16. Surface Modification of Carbon Nanotubes with Conjugated Polyelectrolytes: Fundamental Interactions and Applications in Composite Materials, Nanofibers, Electronics, and Photovoltaics

    Ezzeddine, Alaa

    2015-10-01

    Ever since their discovery, Carbon nanotubes (CNTs) have been renowned to be potential candidates for a variety of applications. Nevertheless, the difficulties accompanied with their dispersion and poor solubility in various solvents have hindered CNTs potential applications. As a result, studies have been developed to address the dispersion problem. The solution is in modifying the surfaces of the nanotubes covalently or non-covalently with a desired dispersant. Various materials have been employed for this purpose out of which polymers are the most common. Non-covalent functionalization of CNTs via polymer wrapping represents an attractive method to obtain a stable and homogenous CNTs dispersion. This method is able to change the surface properties of the nanotubes without destroying their intrinsic structure and preserving their properties. This thesis explores and studies the surface modification and solublization of pristine single and multiwalled carbon nanotubes via a simple solution mixing technique through non-covalent interactions of CNTs with various anionic and cationic conjugated polyelectrolytes (CPEs). The work includes studying the interaction of various poly(phenylene ethynylene) electrolytes with MWCNTs and an imidazolium functionalized poly(3-hexylthiophene) with SWCNTs. Our work here focuses on the noncovalent modifications of carbon nanotubes using novel CPEs in order to use these resulting CPE/CNT complexes in various applications. Upon modifying the CNTs with the CPEs, the resulting CPE/CNT complex has been proven to be easily dispersed in various organic and aqueous solution with excellent homogeneity and stability for several months. This complex was then used as a nanofiller and was dispersed in another polymer matrix (poly(methyl methacrylate), PMMA). The PMMA/CPE/CNT composite materials were cast or electrospun depending on their desired application. The presence of the CPE modified CNTs in the polymer matrix has been proven to enhance

  17. Development of mats composed by TiO{sub 2} and carbon dual electrospun nanofibers: A possible anode material in microbial fuel cells

    Garcia-Gomez, Nora A.; Balderas-Renteria, Isaias [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Av. Universidad S/N Cd. Universitaria San Nicolás de los Garza Nuevo León, C.P. 66451 México (Mexico); Garcia-Gutierrez, Domingo I. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Av. Universidad S/N Cd. Universitaria San Nicolás de los Garza Nuevo León, C.P. 66451 México (Mexico); Universidad Autónoma de Nuevo León, Centro de Innovación, Investigación y Desarrollo en Ingeniería y Tecnología, PIIT, Av. Universidad S/N Cd. Universitaria San Nicolás de los Garza Nuevo León, C.P. 66451 México (Mexico); Mosqueda, Hugo A. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Av. Universidad S/N Cd. Universitaria San Nicolás de los Garza Nuevo León, C.P. 66451 México (Mexico); and others

    2015-03-15

    Highlights: • Dual nanofiber of TiO{sub 2}–C/C showed excellent electrical performance. • TiO{sub 2}–C/C dual nanofiber can host a dense biofilm of electroactivated Escherichia coli. • Dual nanofibers can be applied as anode to obtain electricity in microbial fuel cells. - Abstract: A new material based on TiO{sub 2(rutile)}–C{sub (semi-graphitic)}/C{sub (semi-graphitic)} dual nanofiber mats is presented, whose composition and synthesis methodology are fundamental factors for the development of exoelectrogenic biofilms on its surface. Therefore, this material shows the required characteristics for possible applications in the bioconversion process of an organic substrate to electricity in a microbial fuel cell. Chronoamperometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and electrical conductivity analyses showed excellent electrical performance of the material for the application intended; a resistance as low as 3.149 Ω was able to be measured on this material. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies confirmed the morphology sought on the material for the application intended, dual nanofibres TiO{sub 2(rutile)}–C{sub (semi-graphitic)}/C{sub (semi-graphitic)} with a side by side configuration. The difference in composition of the fibers forming the dual nanofibers was clearly observed and confirmed by energy dispersive X-ray spectroscopy (EDXS), and their crystal structure was evident in the results obtained from selected area electron diffraction (SAED) studies. This nanostructured material presented a high surface area and is biocompatible, given that it can host a dense biofilm of electroactivated Escherichia coli. In this study, the maximum current density obtained in a half microbial fuel cell was 8 A/m{sup 2} (0.8 mA/cm{sup 2})

  18. Development of mats composed by TiO2 and carbon dual electrospun nanofibers: A possible anode material in microbial fuel cells

    Highlights: • Dual nanofiber of TiO2–C/C showed excellent electrical performance. • TiO2–C/C dual nanofiber can host a dense biofilm of electroactivated Escherichia coli. • Dual nanofibers can be applied as anode to obtain electricity in microbial fuel cells. - Abstract: A new material based on TiO2(rutile)–C(semi-graphitic)/C(semi-graphitic) dual nanofiber mats is presented, whose composition and synthesis methodology are fundamental factors for the development of exoelectrogenic biofilms on its surface. Therefore, this material shows the required characteristics for possible applications in the bioconversion process of an organic substrate to electricity in a microbial fuel cell. Chronoamperometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and electrical conductivity analyses showed excellent electrical performance of the material for the application intended; a resistance as low as 3.149 Ω was able to be measured on this material. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies confirmed the morphology sought on the material for the application intended, dual nanofibres TiO2(rutile)–C(semi-graphitic)/C(semi-graphitic) with a side by side configuration. The difference in composition of the fibers forming the dual nanofibers was clearly observed and confirmed by energy dispersive X-ray spectroscopy (EDXS), and their crystal structure was evident in the results obtained from selected area electron diffraction (SAED) studies. This nanostructured material presented a high surface area and is biocompatible, given that it can host a dense biofilm of electroactivated Escherichia coli. In this study, the maximum current density obtained in a half microbial fuel cell was 8 A/m2 (0.8 mA/cm2)

  19. Porous block nanofiber composite filters

    Ginley, David S.; Curtis, Calvin J.; Miedaner, Alexander; Weiss, Alan J.; Paddock, Arnold

    2016-08-09

    Porous block nano-fiber composite (110), a filtration system (10) and methods of using the same are disclosed. An exemplary porous block nano-fiber composite (110) includes a porous block (100) having one or more pores (200). The porous block nano-fiber composite (110) also includes a plurality of inorganic nano-fibers (211) formed within at least one of the pores (200).

  20. Templates for integrated nanofiber growth

    Oliveira Hansen, Roana Melina de

    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 singl...

  1. Electrochemical determination of dopamine based on electrospun CeO2/Au composite nanofibers

    An electrochemical method for the detection of dopamine based on a glass carbon electrode modified with electrospun CeO2/Au composite nanofibers was investigated in this article. The CeO2/Au composite nanofibers were prepared by the electrospinning technique and then annealed in air. The CeO2/Au composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. Cyclic voltammetry (CV) showed that the electrospun CeO2/Au composite nanofibers modified carbon glass electrode exhibited an excellent electrocatalytic response to the dopamine (DA). The detection limit (S/N = 3) was as low as 0.056 μM and the sensitivity could reach 127 μA mM−1 cm−2. All these demonstrated that the electrospun CeO2/Au composite nanofibers were good electrocatalyst for the oxidation of dopamine

  2. Gas Composition Sensing Using Carbon Nanotube Arrays

    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.

  3. Progress in Studies on Carbon and Silicon Carbide Nanocomposite Materials

    Silicon carbide nanofiber and carbon nanotubes are introduced. The structure and application of nanotubers (nanofibers) in carbon/carbon composites are emphatically presented. Due to the unique structure of nanotubers (nanofibers), they can modify the microstructure of pyrocarbon and induce the deposition of pyrocarbon with high text in carbon/carbon composites. So the carbon/carbon composites modified by CNT/CNF have more excellent properties.

  4. Progress in Studies on Carbon and Silicon Carbide Nanocomposite Materials

    Peng Xiao; Jie Chen; Xian-feng Xu

    2010-01-01

    Silicon carbide nanofiber and carbon nanotubes are introduced. The structure and application of nanotubers (nanofibers) in carbon/carbon composites are emphatically presented. Due to the unique structure of nanotubers (nanofibers), they can modify the microstructure of pyrocarbon and induce the deposition of pyrocarbon with high text in carbon/carbon composites. So the carbon/carbon composites modified by CNT/CNF have more excellent properties.

  5. Nanofiber Filters Eliminate Contaminants

    2009-01-01

    With support from Phase I and II SBIR funding from Johnson Space Center, Argonide Corporation of Sanford, Florida tested and developed its proprietary nanofiber water filter media. Capable of removing more than 99.99 percent of dangerous particles like bacteria, viruses, and parasites, the media was incorporated into the company's commercial NanoCeram water filter, an inductee into the Space Foundation's Space Technology Hall of Fame. In addition to its drinking water filters, Argonide now produces large-scale nanofiber filters used as part of the reverse osmosis process for industrial water purification.

  6. Optimizing strength and toughness of nanofiber-reinforced CMCs

    Pavia, F.; Curtin, W. A.

    2012-09-01

    Nanofibers used in current ceramic matrix composites (CMCs) are usually wavy and of finite length. Here, a shear-lag model for predicting the tensile strength and work of fracture of a composite containing a "single matrix crack", as a function of all the material parameters including constant plus Coulomb interfacial friction, is presented for a CMC containing wavy, finite-length nanofibers having a statistical distribution of strengths. Literature results are recovered for straight infinite fibers, with strength and toughness depending on a characteristic strength σc and a characteristic length δc. For nanofibers of finite length L, radius of curvature R, and with Coulomb friction coefficient μ, the strength and toughness are found to depend only on σc, δc, and two new dimensionless parameters μδc/R and L/δc. Parametric results for a typical carbon nanotube CMC show an optimal region of morphology (L and R) that maximizes composite strength and toughness, exceeding the properties of composites with straight (R=∞) and/or long (L=∞) reinforcements. Therefore, while factors such as the nanofiber strength distribution and the nanofiber-matrix interface sliding resistance may not be easily controlled, the tuning, via processing, of purely geometrical properties of the nanofibers (L and R) alone can aid in maximizing composite properties. These results have important application in hybrid CMCs such as "fuzzy fiber" CMCs, where micron-scale fibers are covered with a forest of nanofibers such that the nanofiber array can bridge longitudinal cracks and thus improve delamination resistance.

  7. Nanomechanical testing of polymeric nanofibers

    Tan, E. P. S.; Lim, C. T.

    2005-04-01

    Biodegradable polymeric nanofibrous scaffold comprises individual nanofibers where their stiffnesses can promote or undermine the various cellular functions as well as structural integrity of the scaffold. As such, there is a need to investigate the nanomechanical properties of these individual nanofibers. However, conducting mechanical tests of individual fibers at the nanometer scale can pose great challenges and difficulties. Here, we present novel techniques to perform nanomechanical testing of individual polymeric nanofibers. For demonstration of the nano tensile tests, polycaprolactone (PCL) nanofibers were produced via electrospinning. These fibers were deposited across two parallel edges of a cardboard frame so that a single nanofiber can be isolated for tensile test using a nano tensile tester. For nanoscale three-point bend test, a Poly (L-lactic acid) (PLLA) nanofiber was suspended across a microsized groove etched on a silicon wafer. An atomic force microscope (AFM) tip was then used to apply a point load on the mid-span of the suspended fiber. Beam bending theory was then used to calculate the elastic modulus of the nanofiber. For nanoindentation test, a PLLA nanofiber was deposited on a mica substrate and an AFM tip used to indent the nanofiber. Modified Hertz theory for normal contact was then used to evaluate the elastic modulus of the nanofiber.

  8. Synthesis of silicon monoxide–pyrolytic carbon–carbon nanofiber composites and their hybridization with natural graphite as a means of improving the anodic performance of lithium-ion batteries

    Novel composites of silicon monoxide, pyrolytic carbon and carbon nanofiber (SiO/PyC/CNF) were hybridized with natural graphite (NG) as a means of improving the anodic performance of Li-ion batteries. Samples were made with hybridization levels of 10–30 wt% of NG exhibited excellent cyclability with a discharge capacity of 389–522 mAh g−1 in a Li-ion battery system. SiO/PyC/CNF composite hybrids showed better cyclability than other carbon composites containing SiO/PyC and SiO/CNF. These hybridization effects were attributed to the lower contact resistance of SiO/PyC/CNF in the electrode. The internal spaces created throughout the SiO/PyC/CNF composite and their effect on material dispersion in the hybridized electrodes may have prevented electrode damage by relieving tensions induced by the expansion of SiO particles in the electrode over the course of repeated charge and discharge processes. (paper)

  9. Ultrasonic dyeing of cellulose nanofibers.

    Khatri, Muzamil; Ahmed, Farooq; Jatoi, Abdul Wahab; Mahar, Rasool Bux; Khatri, Zeeshan; Kim, Ick Soo

    2016-07-01

    Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing. PMID:26964959

  10. Electrospun nanofibers: solving global issues

    Seeram Ramakrishna

    2006-03-01

    Full Text Available Nanofibers are able to form a highly porous mesh and their large surface-to-volume ratio improves performance for many applications. Electrospinning has the unique ability to produce nanofibers of different materials in various fibrous assemblies. The relatively high production rate and simplicity of the setup makes electrospinning highly attractive to both academia and industry. A variety of nanofibers can be made for applications in energy storage, healthcare, biotechnology, environmental engineering, and defense and security.

  11. Tailored surface structure of LiFePO4/C nanofibers by phosphidation and their electrochemical superiority for lithium rechargeable batteries.

    Lee, Yoon Cheol; Han, Dong-Wook; Park, Mihui; Jo, Mi Ru; Kang, Seung Ho; Lee, Ju Kyung; Kang, Yong-Mook

    2014-06-25

    We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO4/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO4/C nanofibers composed of 1-dimensional (1D) LiFePO4 nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO4 nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO4/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO4 nanofibers. As a result, the phosphidated LiFePO4/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO4/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials. PMID:24786736

  12. Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

    Kohlman, Lee W.; Bakis, Charles; Williams, Tiffany S.; Johnston, James C.; Kuczmarski, Maria A.; Roberts, Gary D.

    2014-01-01

    Composite materials offer significant weight savings in many aerospace applications. The toughness of the interface of fibers crossing at different angles often determines failure of composite components. A method for toughening the interface in fabric and filament wound components using directly electrospun thermoplastic nanofiber on carbon fiber tow is presented. The method was first demonstrated with limited trials, and then was scaled up to a continuous lab scale process. Filament wound tubes were fabricated and tested using unmodified baseline towpreg material and nanofiber coated towpreg.

  13. Application of Nanofiber Technology to Nonwoven Thermal Insulation

    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.

  14. Preparation of MnO nanofibers by novel hydrothermal treatment of manganese acetate/PVA electrospun nanofiber mats

    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.

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

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

    2016-06-15

    Nanoporous alumina membranes are filled with multiwalled carbon nanotubes (MWCNTs) and then poly(3-hexylthiophene-2,5-diyl) (P3HT) melt, resulting in nanofibers with nanoconfinement induced coalignment of both MWCNT and polymer chains. The simple sonication process proposed here can achieve vertically aligned arrays of P3HT/MWCNT composite nanofibers with 3 wt % to 55 wt % MWCNT content, measured using thermogravimetric methods. Electrical and thermal transport in the composite nanofibers improves drastically with increasing carbon nanotube content where nanofiber thermal conductivity peaks at 4.7 ± 1.1 Wm(-1)K(-1) for 24 wt % MWCNT and electrical percolation occurs once 20 wt % MWCNT content is surpassed. This is the first report of the thermal conductivity of template fabricated composite nanofibers and the first proposed processing technique to enable template fabrication of composite nanofibers with high filler content and long aspect ratio fillers, where enhanced properties can also be realized on the macroscale due to vertical alignment of the nanofibers. These materials are interesting for thermal management applications due to their high thermal conductivity and temperature stability. PMID:27200459

  16. Confined growth of carbon nanoforms in one-dimension by fusion of anthracene rings inside the pores of MCM-41

    Bosch-Navarro, Concha; Coronado, Eugenio; Martí-Gastaldo, Carlos; Amorós, Pedro

    2014-06-01

    We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host.We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host. Electronic supplementary information (ESI) available: Synthesis details, SEM and additional HR-TEM images, FT-IR spectra, EDAX microanalysis and pore distribution of loaded MCM41@anth. See DOI: 10.1039/c3nr06669j

  17. Investigating Impact of The Interfacial Debonding on The Mechanical Propertiesof NanoFiber Reinforced Composites

    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.

  18. Egg-Box Structure in Cobalt Alginate: A New Approach to Multifunctional Hierarchical Mesoporous N-Doped Carbon Nanofibers for Efficient Catalysis and Energy Storage

    Li, Daohao; Lv, Chunxiao; Liu, Long; Xia, Yanzhi; She, Xilin; Guo, Shaojun; Yang, Dongjiang

    2015-01-01

    Carbon nanomaterials with both doped heteroatom and porous structure represent a new class of carbon nanostructures for boosting electrochemical application, particularly sustainable electrochemical energy conversion and storage applications. We herein demonstrate a unique large-scale sustainable biomass conversion strategy for the synthesis of earth-abundant multifunctional carbon nanomaterials with well-defined doped heteroatom level and multimodal pores through pyrolyzing electrospinning r...

  19. Metal current collector-free freestanding silicon–carbon 1D nanocomposites for ultralight anodes in lithium ion batteries

    Choi, Jang Wook

    2010-12-15

    Although current collectors take up more weight than active materials in most lithium ion battery cells, so far research has been focused mainly on improving gravimetric capacities of active materials. To address this issue of improving gravimetric capacities based on overall cell components, we develop freestanding nanocomposites made of carbon nanofibers (CNFs) and silicon nanowires (SiNWs) as metal current collector-free anode platforms. Intrinsically large capacities of SiNWs as active materials in conjunction with the light nature of freestanding CNF films allow the nanocomposites to achieve 3-5 times improved gravimetric capacities compared to what have been reported in the literature. Moreover, three-dimensional porous structures in the CNF films facilitate increased mass loadings of SiNWs when compared to flat substrates and result in good cycle lives over 40 cycles. This type of nanocomposite cell suggests that 3D porous platforms consisting of light nanomaterials can provide for higher gravimetric and areal capacities when compared to conventional battery cells based on flat, heavy metal substrates. © 2010 Elsevier B.V. All rights reserved.

  20. Electrospun Gallium Nitride Nanofibers (abstract)

    Meléndez, Anamaris; Morales, Kristle; Ramos, Idalia; Campo, Eva; Santiago, Jorge J.

    2009-04-01

    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.

  1. New High-Energy Nanofiber Anode Materials

    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 μm 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.

  2. Mechanism of nanofiber crimp

    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.

  3. Nanofiber-segment ring resonator

    Jones, D E; Franson, J D; Pittman, T B

    2016-01-01

    We describe a fiber ring resonator comprised of a relatively long loop of standard single-mode fiber with a short nanofiber segment. The evanescent mode of the nanofiber segment allows the cavity-enhanced field to interact with atoms in close proximity to the nanofiber surface. We report on an experiment using a warm atomic vapor and low-finesse cavity, and briefly discuss the potential for reaching the strong coupling regime of cavity QED by using trapped atoms and a high-finesse cavity of this kind.

  4. Hydrogen storage in graphite nanofibers

    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.

  5. Quasi one dimensional transport in individual electrospun composite nanofibers

    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 α ∼ 2.9−10.2. The current also behaves as power law of voltage with an exponent of β ∼ 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 αbulk ∼ 0.06 which agrees with theoretical predictions

  6. Oxolane-2,5-dione modified electrospun cellulose nanofibers for heavy metals adsorption

    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.

  7. Electrospun Nanofibers Applications in Dentistry

    Seog-Jin Seo

    2016-01-01

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

  8. Binary CuO/Co3O4 nanofibers for ultrafast and amplified electrochemical sensing of fructose

    Highlights: → Binary CuO/Co3O4 nanofiber as active electrode material. → Dramatically enhanced catalytic activity and direct fructose detection. → Significantly lowered overpotential, ultrafast (1 s) and sensitive (18.988 μA mM-1) response. - Abstract: Cobalt oxide-doped copper oxide composite nanofibers (CCNFs) were successfully achieved via electrospinning followed by thermal treatment processes and then exploited as active electrode material for direct enzyme-free fructose detection. The morphology and the structure of as-prepared samples were investigated by X-ray diffraction spectrum (XRD) and scanning electron microscopy (SEM). The electrocatalytic activity of CCNFs films towards fructose oxidation and sensing performances were evaluated by conventional electrochemical techniques. Cyclic voltammetry (CV) and chronoamperometry (I-t) revealed the distinctly enhanced sensing properties towards fructose compared to pure copper oxide nanofibers (CNFs), i.e., showing significantly lowered overpotential of 0.30 V, ultrafast (1 s) and ultrasensitive (18.988 μA mM-1) current response in a wide linear range of 1.0 x 10-5 M to 6.0 x 10-3 M with satisfied reproducibility and stability, which could be ascribed to the synergic catalytic effect of the binary CuO/Co3O4 composite nanofibers and the highly porous three-dimensional network films structure of the CCNFs. In addition, a good selectivity for fructose detection was achieved. Results in this work demonstrated that CCNFs is one of the promising catalytic electrode materials for enzymeless fructose sensor fabrication.

  9. Binary CuO/Co{sub 3}O{sub 4} nanofibers for ultrafast and amplified electrochemical sensing of fructose

    Wang Yang [College of Chemistry, Jilin University, Changchun 130012 (China); Wang Wen [Yantai Wanhua Polyurethanes Co., Ltd., Shandong 264002 (China); Song Wenbo, E-mail: wbsong@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

    2011-11-30

    Highlights: > Binary CuO/Co{sub 3}O{sub 4} nanofiber as active electrode material. > Dramatically enhanced catalytic activity and direct fructose detection. > Significantly lowered overpotential, ultrafast (1 s) and sensitive (18.988 {mu}A mM{sup -1}) response. - Abstract: Cobalt oxide-doped copper oxide composite nanofibers (CCNFs) were successfully achieved via electrospinning followed by thermal treatment processes and then exploited as active electrode material for direct enzyme-free fructose detection. The morphology and the structure of as-prepared samples were investigated by X-ray diffraction spectrum (XRD) and scanning electron microscopy (SEM). The electrocatalytic activity of CCNFs films towards fructose oxidation and sensing performances were evaluated by conventional electrochemical techniques. Cyclic voltammetry (CV) and chronoamperometry (I-t) revealed the distinctly enhanced sensing properties towards fructose compared to pure copper oxide nanofibers (CNFs), i.e., showing significantly lowered overpotential of 0.30 V, ultrafast (1 s) and ultrasensitive (18.988 {mu}A mM{sup -1}) current response in a wide linear range of 1.0 x 10{sup -5} M to 6.0 x 10{sup -3} M with satisfied reproducibility and stability, which could be ascribed to the synergic catalytic effect of the binary CuO/Co{sub 3}O{sub 4} composite nanofibers and the highly porous three-dimensional network films structure of the CCNFs. In addition, a good selectivity for fructose detection was achieved. Results in this work demonstrated that CCNFs is one of the promising catalytic electrode materials for enzymeless fructose sensor fabrication.

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

    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.

  11. Electrospun Nanofibers Applications in Dentistry

    Seo, Seog-Jin; Kim, Hae-Won; Lee, Jung-Hwan

    2016-01-01

    Nanofibrous structures exhibit many interesting features, such as high surface area and surface functionalization and porosity in the range from submicron to nanoscale, which mimics the natural extracellular matrix. In particular, electrospun nanofibers have gained great attention in the field of tissue engineering due to the ease of fabrication and tailorability in pore size, scaffold shape, and fiber alignment. For the reasons, recently, polymeric nanofibers or bioceramic nanoparticle-incor...

  12. COAL REINFORCED COMPOSITE POLYAMIDE NANOFIBERS

    R. Keskin; I. Gocek; U. K. Sahin; O. B. Berkalp; N. Acarkan; Ozkan, S.; C. D. Dikmen; E. Daskaya; H. Saglam

    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...

  13. Aligned Layers of Silver Nano-Fibers

    Golovin, Andrii B.; Liubov Kreminska; Jeremy Stromer

    2012-01-01

    We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polariz...

  14. The formation of titanium dioxide crystallite nanoparticles during activation of PAN nanofibers containing titanium isopropoxide

    Mehrpouya, Fahimeh; Tavanai, Hossein, E-mail: tavanai@cc.iut.ac.ir; Morshed, Mohammad [Isfahan University of Technology, Department of Textile Engineering, Center of Excellence in Applied Nanotechnology (Iran, Islamic Republic of); Ghiaci, Mehran [Isfahan University of Technology, Department of Chemistry (Iran, Islamic Republic of)

    2012-08-15

    Activated carbon (AC) can act as an important carrier for TiO{sub 2} nanoparticles. TiO{sub 2} 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 TiO{sub 2} nanoparticle in AC nanofibers, with a good dispersion in both the longitude and cross section of nanofibers. The TiO{sub 2} crystallite size lies in the range of 7.3-11.3 nm. The dispersion of TiO{sub 2} nanoparticles in the matrix of AC nanofibers is far superior to the direct mixing of TiO{sub 2} nanoparticles in the original electrospinning solution.

  15. Superhydrophobic terpolymer nanofibers containing perfluoroethyl alkyl methacrylate by electrospinning

    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.

  16. Superhydrophobic terpolymer nanofibers containing perfluoroethyl alkyl methacrylate by electrospinning

    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.

  17. A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

    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 μm and 57.9 ± 2.80 μm, 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

  18. A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

    Hsieh, Bao-Yu; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning, E-mail: xjiang5@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhu, Jiadeng; Zhang, Xiangwu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-01-12

    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 μm and 57.9 ± 2.80 μm, 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{sup −3 }Pa/(W/m{sup 2}), 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.

  19. Electrospinning of Nanofibers for Energy Applications

    Guiru Sun

    2016-07-01

    Full Text Available With global concerns about the shortage of fossil fuels and environmental issues, the development of efficient and clean energy storage devices has been drastically accelerated. Nanofibers are used widely for energy storage devices due to their high surface areas and porosities. Electrospinning is a versatile and efficient fabrication method for nanofibers. In this review, we mainly focus on the application of electrospun nanofibers on energy storage, such as lithium batteries, fuel cells, dye-sensitized solar cells and supercapacitors. The structure and properties of nanofibers are also summarized systematically. The special morphology of nanofibers prepared by electrospinning is significant to the functional materials for energy storage.

  20. Preparation of Chitin Nanofibers from Mushrooms

    Hiroyuki Saimoto

    2011-08-01

    Full Text Available Chitin nanofibers were isolated from the cell walls of five different types of mushrooms by the removal of glucans, minerals, and proteins, followed by a simple grinding treatment under acidic conditions. The Chitin nanofibers thus obtained have a uniform structure and a long fiber length. The width of the nanofibers depended on the type of mushrooms and varied in the range 20 to 28 nm. The Chitin nanofibers were characterized by elemental analyses, FT-IR spectra, and X-ray diffraction profiles. The results showed that the α-chitin crystal structure was maintained and glucans remained on the nanofiber surface.