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Oxidized and reduced carbon nanofibers (OCNF and RCNF) were used as supports to prepare highly dispersed PtRu catalysts for the direct methanol fuel cells (DMFC). The structural and surface features and electrocatalytic properties of bimetallic PtRu/OCNF and PtRu/RCNF were extensively investigated. FT-IR spectra show that carboxyl groups exist on the surface of the OCNF, which greatly influence the...
Carbon nanofibers (CNF) are non-microporous graphitic materials with a high surface area (100–200m 2 /g), high purity and tunable surface chemistry. Therefore the material has a high potential for use as catalyst support. However, in some instances it is claimed that the low density and low mechanical strength of the macroscopic particles hamper their application. In this study we show that...
Widely different hydrogen adsorption capacities have been reported for a variety of carbon materials which have attracted attention for hydrogen storage. This has led to doubts as to the validity of some of the claims and it has been suggested that one possible reason for the disparate hydrogen sorption capacities may lie in the inaccurate measurement of the hydrogen adsorbed. The aim of the work...
Activated carbon fiber fabrics, an excellent adsorbent, were used as catalyst supports to grow carbon nanofibers. Because of the microporous structure of the activated carbon fibers, the catalysts could be distributed uniformly on the carbon surface. Based on this concept, the carbon nanofibers can be grown directly on the activated carbon fiber fabrics. We demonstrate that carbon nanofibers with...
Carbon nanofibers (CNFs) have been synthesized by co-catalyst deoxidization process by a reaction between C 2 H 5 OC 2 H 5 , Zn and Fe powder at 650°C for 10h. These nanofibers exhibit diameters of ∼80nm and lengths ranging from several micrometers to tens of micrometers. X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy indicate...
Multi-branched carbon nanofibers with a porous structure have been synthesized on a Cu catalyst doped with Li, Na, or K. The products were characterized by field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy. Using this new type of nanofiber as polarized electrodes, an electrochemical double-layer capacitor...
Carbon nanofibers were produced by the catalytic CVD process by the floating catalyst method, in semi-industrial systems at temperatures above 1350K. Iron-derived carbon nanofibers were produced from natural gas and xylene, using ferrocene as catalyst source, yielding a thickened submicron vapor grown carbon fibers with a core of multi-wall nanotubes. For the production of Ni derived nanofibers, natural...
Carbon nanotubes (CNTs) doped with a range of nitrogen contents (0–10at.%) were prepared via a floating catalyst CVD method using ferrocene, NH 3 , and xylene or pyridine. XPS and Raman microscopy were used to assess quantitatively the compositional and structural properties of the nitrogen-doped carbon nanotubes (N-CNTs). XPS analysis indicates a shift in and broadening of the C1s spectra...
A novel high strength graphitic foam was produced through the incorporation of carbon nanofibers into a pitch based precursor. The nanofiber reinforced cellular foams were mechanically tested both from a localized and bulk perspective with results indicating enhanced foam performance with nanofiber addition. The magnitude of increased performance was a result of both the nanofiber itself as well as...
The synthesis of carbon nanofibers was carried out by catalytic decomposition of ethylene in presence of hydrogen. Bimetallic catalysts, e.g. Fe–Cu or Ni–Cu, were synthesized by coprecipitation, reduction–precipitation and reverse microemulsion techniques and were proven to have a strong influence on the morphology of the nanofibers. The best results in terms of synthesis homogeneity were obtained...
Nitrogen molecules have been encapsulated into the central hollows of vertically aligned carbon nitride (CN) multiwalled nanofibers by dc plasma-enhanced chemical vapor deposition with C 2 H 2 , NH 3 , and N 2 gases on a Ni/TiN/Si(100) substrate at 650°C. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectra showed the existence of nitrogen...
Platelet graphite nanofibers are materials produced from the decomposition of carbon monoxide and hydrogen over iron powders. The surface consists of terminated graphite edges, differing from traditional graphite materials in which basal plane graphite surfaces dominate. The 3-dimensional morphology and crystal face exposure on the nanofiber surface was determined by selected area electron diffraction...
We describe a process of catalytic hydrocarbon pyrolysis which yields a new class of carbon nanotubes/nanofilaments (NT/NFs). It is characterized by high temperature (1000–1050°C), and higher concentrations of gaseous species normally active in coke formation. Usually coke growth quickly encapsulates a catalyst particle in such environments, which in turn blocks further NT/NF growth. In our case the...
Inspired by a special biological structure in nature, a kind of urchin-like nano/micro hybrid design was proposed to modify conventional micrometer-sized electroactive materials for lithium ion battery (LIB). By catalytic chemical vapor deposition to in situ grow carbon nanofibers on the surface of natural graphite spheres, we fabricated the nano/micro hybrid composite with an urchin-like structure...
The possibility of growing carbon nanotubes in the immediate proximity of microstructures on a surface in a controllable way, with a high degree of control over the inclination angle, is demonstrated. Carbon nanotubes synthesised in a plasma-enhanced chemical vapour deposition process are known to grow in the direction of the electrical field. Geometrical features of the conductive substrate holder...
The addition of nanofeatures to carbon microelectromechanical system (C-MEMS) structures would greatly increase surface area and enhance their performance in miniature batteries, super-capacitors, electrochemical and biological sensors. Negative photoresist posts were patterned on a Au/Ti contact layer by photolithography. After pyrolyzing the photoresist patterns to carbon patterns, graphitic nanofibers...
The use of selected area electron diffraction and centered dark field imaging using a transmission electron microscope is demonstrated for studying the herringbone structure of carbon nanofibers (CNFs). The experimental method is described and illustrated with CNFs that were grown via a chemical vapor deposition method with a nickel catalyst. It is demonstrated that this method gives the angle of...
Catalytically grown carbon nanofibers, a novel mesoporous carbon material for catalysis, were synthesized by the decomposition of carbon-containing gases (CH 4 , C 2 H 4 or CO) over supported nickel-iron alloy and unsupported iron. It was shown that the structures of as-synthesized and modified CNFs, including the arrangement of the graphenes in CNF, and the crystallinity and...
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