Fibrous Carbon Materials Research Articles

Liquid Crystals of Lithium Dodecylbenzenesulfonate for Electric Double Layer Capacitors

Ionic lyotropic liquid crystals based on lithium dodecylbenzenesulfonate were used as electrolytes for electric double layer capacitors with carbon fibrous electrodes. The capacitors were tasted by cyclic voltammetry, galvanostatic charge and discharge, and impedance spectroscopy. The highest specific capacitance was achieved for electrical double layer capacitor equipped with ionic lyotropic liquid crystal of lithium dodecylbenzenesulfonate 35wt% in water. The specific capacitance of capacitor was calculated from galvanostatic discharge curves – 15F/g of carbon fibrous material

Electrochemical modification of a nonwoven fibrous carbon material in sulfuric acid solution

The influence exerted by the electrode polarization of ANM nonwoven fibrous carbon material in 0.25 M sulfuric acid solution on the pore composition and size, fiber surface morphology, elemental composition of fibers, quantitative and qualitative composition of surface groups, stationary electrode potential, and electrochemical capacity was examined. These properties depend on the ratio of the cathodic and anodic constituents of the current density (measured per geometric surface area).

Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene

AbstractWe report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.

Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene.

We report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.

Research progress on fibrous carbon materials as anode materials for lithium ion batteries

Fibrous carbon materials have a variety of dimensions and structures. However, these materials were earlier restricted for use as anode materials for lithium ion batteries due to their cost and performance. With the development of nanotechnology, some modified and new forms of carbon fibers have emerged, which show good performance as anode materials. This paper reviews recent domestic and foreign research progress on fibrous carbon materials as anode materials. The electrochemical performance and prospective use of graphite fibers, carbon fibers and carbon nanofibers for this purpose are summarized. Research has ranged from non-graphitized to graphitized carbon fibers, from micron to nanometer diameter, and has focused on the parameters of their preparation to the design of their microstructure. Fibrous carbon materials are likely to be important alternatives for carbon anode materials in the future based on their high capacity, high rate capability, low cost and ease of industrialization. [New Carbon Materials 2015, 30(1): 1–11]

Cellular automata simulation of osteoblast growth on microfibrous-carbon-based scaffolds.

The objective of this study was to investigate the use of three fibrous carbon materials (T300, P25, and P120) for bone repair and develop and validate theoretical and computational methods in which bone tissue regeneration and repair could be accurately predicted. T300 was prepared from polyacrylonitrile precursor while P25 and P120 fibers were prepared from pitch, both common fiber precursors. Results showed that osteoblast growth on carbon scaffolds was enhanced with increased crystallinity, surface roughness, and material orientation. For unidirectional scaffolds at 120 h, there was 33% difference in cell growth between T300 and P25 fibers and 64% difference between P25 and P120 fibers. Moreover, for multidirectional fibers at 120 h, there was 35% difference in cell growth between T300 and P25 fibers and 43% difference between P25 and P120 fibers. Results showed that material alignment was integral to promoting cell growth with multidirectional scaffolds having the capacity for greater growth over unidirectional scaffolds. At 120 h there was 24% increase in cell growth between unidirectional alignment and multidirectional alignment on high-crystalline carbon fibers. Ultimately, data indicated that carbon scaffolds exhibited excellent bioactivity and may be tuned to stimulate unique reactions. Additionally, numerical and computational simulations provided evidence that corroborated experimental data with simulations. Results illustrated the capability of cellular automata models for assessing osteoblast cell response to biomaterials.

Modeling of electrochemical process in flow 3D electrode with account for distribution of flow velocity of electrolyte in electrode

A mathematical model of the electrochemical metal deposition process in a flow 3D electrode is developed with account for dynamic distribution of the flow velocity of electrolyte, metal mass, potential, porosity, conductivity, specific electrode surface area, and other characteristics in the local volume of the electrode. These characteristics of the process and electrode are considered as functions of time and coordinate within the electrode. The results of experimental studies and calculations of copper electrodeposition process from ammonium sulfate electrolyte onto cathodes of graphitized carbon fibrous materials with different conductivity are presented at different initial flow velocities of electrolyte.

Carbon nanofibers prepared by the carbonization of self-assembled cellulose nanocrystals

In this study, we fabricated fibrous carbon materials by using self-assembled cellulose nanocrystal fibers as the precursor. Cellulose nanocrystals at low concentrations, which were isolated from commercial microcystallline cellulose by a sulfuric acid treatment, were self-assembled into fibrous cellulose particles during the frozen process. After a stabilization process, the cellulose nanocrystal fibers were carbonized at 1,000 °C. Field-emission scanning electron microscopy, Raman spectroscopy, and wide-angle X-ray diffraction analysis were used to confirm the formation of amorphous carbon fibers from the cellulose nanocrystal fibers. Open image in new window

Preparation of carbon nanomaterials in the process of organochlorine waste utilization

A method for the catalytic processing of chlorine-substituted hydrocarbons with the production of a fibrous carbon material is considered. This method is suitable for the utilization of organochlorine chemical industry wastes. The method is based on the carbide cycle mechanism, which was described earlier for the process of hydrocarbon decomposition with the formation of the base structures of carbon nanomaterials. Depending on temperature and hydrogen concentration, the process is performed in two regimes: by the carbide cycle mechanism with the deposition of carbon or by the mechanism of hydrodechlorination with the production of corresponding hydrocarbons. It was found that the presence of chlorine in the system changed the character of carbon diffusion through a catalyst particle, which is responsible for the formation of highly defective filaments with a featherlike morphology and a developed surface area (to 400 m2/g). A demonstration retrofit for the conversion of liquid organochlorine wastes with the production of featherlike carbon was developed. The use of massive alloys as catalyst precursors made it possible to obtain a high yield of carbon product (to 500 g/(g Ni)).

Using formic acid vapor as reducer to prepare Pt nanoparticles supported on carbon nanofiber mats for methanol electrooxidation

A novel process has been developed to prepare well-dispersed Pt nanoparticles on electrospinning-derived carbon fibrous mats (CFMs), which involved the physical adsorption of H2PtCl6 on CFMs and the reduction of H2PtCl6 with formic acid vapor. The most important advantage of this method is its simplicity, solvent-saving and benign to the environment. The performance of the prepared Pt-CFMs electrodes for methanol oxidation has been investigated and the results demonstrate that Pt-CFMs exhibit higher electrocatalytic activity and stability towards methanol oxidation and better tolerance towards reaction intermediates than commercial Pt/C supported on CFMs.

Lignin-Derived Fused Electrospun Carbon Fibrous Mats as High Performance Anode Materials for Lithium Ion Batteries

A novel biomass-based nitrogen-doped free-standing fused carbon fibrous mat was fabricated from lignin-polyethylene oxide (PEO) (90:10) blend via electrospinning followed by carbonization and thermal annealing in the presence of urea. The morphology and structure of the carbon fibers were characterized by field-emission scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis, and their electrochemical properties were investigated for the first time as anode in lithium ion batteries (LIBs). The fused carbon fibers without nitrogen doping exhibited high specific capacity up to 445 mA h g(-1) at a current density of 30 mA g(-1) (comparable to polyacrylonitrile (PAN) derived carbon nanofibers) and good cyclic stability at different current rates. After thermal annealing in the presence of urea, the charge capacity was further improved to as high as 576 mA h g(-1) and still maintained a good capacity of about 200 mAh g(-1) even at a high current rate of 2000 mA g(-1). This research demonstrates the great promise of lignin-derived nanocarbon materials for applications in energy storage systems.

Preparation and Characterization of Interconnected, Kraft Lignin‐Based Carbon Fibrous Materials by Electrospinning

Inter‐connected carbon sub‐µm fibrous materials are prepared by electrospinning of Kraft lignin solutions in DMF followed by thermal treatment consisting of oxidative thermostabilization at 250 °C and carbonization in the temperature range 600–1000 °C. Inter‐fiber bonding is achieved by taking advantages of the intrinsic differences in thermal mobility between different Kraft lignin fractions. Inter‐fiber bonding is observed to enhance the mechanical properties of both the thermostabilized and carbonized materials and enhances the electrical conductivity of the carbonized materials. The surface area, morphological, and structural characteristics are also characterized by the BET method, scanning electron microscopy, and Raman spectroscopy, respectively.

Characterization of nanoporous carbon fibrous materials obtained by chemical activation of plane tree seed under ultrasonic irradiation

An ultrasonic irradiation was applied for the impregnation by chemical agents in the chemical activation process of new type of active carbon precursor. Plane tree seed, due to the unique fibrous structure and low cost is a promising eco-friendly raw material for the preparation of activated carbon materials. Ultrasonic irradiation was used for the impregnation step allowing the chemical activation by different agents: potassium or sodium hydroxide, hydrogen peroxide and pyrogallol. The porous structures were examined by nitrogen adsorption/desorption isotherms at 77K and electrochemically by cyclic voltammetry. The textures of these materials were observed by scanning electron microscopy. The application of ultrasonic irradiation in the impregnation step increased surface area of the final material more than two times in comparison to the material which impregnation in the activation process was by conventional stirring. Ultrasonic irradiation enhances the chemical activation process and the activated carbon fibrous materials with nanoporous structure were obtained by impregnation of seeds with alkaline hydroxides. Total surface areas of these samples were 976m2g−1 and 1130m2g−1. These fibers have total specific capacitance as high as 125Fg−1 and 53Fg−1 which major fraction in both cases originate from internal micropores structure.

Interfacial Nanostructure of the Polymer Electrolyte Fuel Cell Catalyst Layer Constructed with Different Ionomer Contents

Fibrous carbon materials such as carbon nanotubes (CNTs) and carbon nanofilaments (CNFs) have attracted attention for use in the polymer electrolyte fuel cells (PEFCs). We have applied one type of fibrous carbon materials named Marimo carbon (MC) as the catalyst support. The modified nanocolloidal method was used preparing the Marimo carbon supported Pt catalyst (Pt/MC). And then, ionomer/carbon ratio in the cathode catalyst layer of the PEFC has been investigated for its effect on performance and structure of the membrane electrode assembly (MEA). The morphologies and cell performance of cathode catalyst layer using Marimo carbon changed dramatically with ionomer content. In case of excess ionomer, the air volume between CNFs was plugged up by ionomer, and blocked supply fuel gas diffusion caused decrease cell performance. PEFC cell performance was increase with decreasing ionomer content.

Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

Influence of Ionomer/Carbon Ratio on the Performance of a Polymer Electrolyte Fuel Cell

We have used fibrous carbon materials as polymer electrolyte fuel cell (PEFC) electrodes. We have examined the influence of the ionomer/carbon ratio on the performance of the PEFCs. The Marimo carbon is a kind of carbon with a spherical shape, and consists of carbon nanofilaments. Fibrous carbon materials have large specific surface areas without fine pores. The reactant gases and generated water can easily diffuse among the nanofilaments. The ionomer plays two roles; one is a proton transfer activity, and the other is binding the catalyst electrodes. An excess ionomer interferes with the diffusion of gases. The ionomer/carbon ratio should affect the performance of the PEFC, especially at a high current density.

Electrosorption of manganese dioxide on electrochemically modified carbon fiber nonwoven materials

Electrosorption of manganese dioxide on an electrochemically activated carbon fiber nonwoven electrode was studied as influenced by the current density, solution flow-through rate, and concentration of the MnO(OH)2 colloid solution. It was found that manganese hydroxide can be deposited onto electrochemically activated fibers of fibrous carbon materials by different methods: (1) electrosorption of MnO(OH)2 from its colloid solution, (2) synthesis of MnO(OH)2 directly on the fibrous carbon material sample, and (3) impregnation with an MnO(OH)2 colloid solution.

Перспективные электродные материалы для суперконденсаторов

In this review electrochemical and structural data for the electrodes made of certain of perspective materials for supercapacitors are considered. These electrodes were made on the basis of high-dispersed carbon materials. The following materials were used: singlelayer and multilayer carbon nanotubes; reduced oxide of graphene; the carbide type activated carbon; polyacrilonitrile fibers treated by carbonization and activation; the activated carbon fibrous material; the activated carbon cloth; a composite of polyporphirine on carbon black; polyporhine of magnesium, electrodeposited on carbon paper; and a polyaniline composite with the singlelayer nanotubes, electrodeposited on carbon paper. The short review of techniques of synthesis of these electrode materials is presented. Comparison of capactance characteristics of these electrodes for the purpose of the recommendation of their use in certain types of electrochemical supercapacitors is carried out.

Hydrolysis of acrylonitrile by nitrile-converting bacterial cells immobilized on fibrous carbon adsorbents

Cells of the Pseudomonas fluorescens strain C2 containing nitrilase and Rhodococcus ruber strain gt1 with nitrile hydratase activity have been immobilized by the use of adsorption on fibrous carbon materials. It has been shown that the maximum adsorption value of Rhodococcus cells is higher than that in pseudomonades, reaching 21 mg of dry cells/1 g of the carrier vs. 6 mg, respectively. Cell adsorption, compared to cell suspension, gives a significant rise in nitrilase activity (by 7.4 times, using Ural TM-4 as the carrier) and in the stability of nitrile hydratase activity (5 reaction cycles without loss of activity, using Carbopon-B-active). Immobilized biocatalysts were also obtained by cell growth from Ps. fluorescens strain C2 and Rhodococcus ruber strain gt1 on fibrous carbon adsorbents. Biocatalyst productivity was higher for both strains when the carbonized material Ural TM-4 was used as the carrier.

Synthesis of alcohols from CO and H2 on iron catalysts containing carbon fiber

It was found that alcohols can be synthesized from CO and H2 at 3 MPa and 280–300°C in the presence of Fe catalysts containing an activated fibrous carbon material (AFCM) as a support. It was established that 20% Fe/AFCM catalysts possess an extremely high specific activity in the conversion of carbon monoxide (∼1 × 10−4 mol CO (mol Fe)−1 s−1), which is higher than the activity of traditional bulk iron catalysts by almost an order of magnitude. The values of CO conversion and selectivity for alcohols obtained for these catalysts are close to the parameters of industrial processes (Synol process, Oxyl process, and synthesis according to Bashkirov); however, they are obtained under milder conditions in a single run rather than with the use of a recycle. The Fe/AFCM catalysts make it possible to obtain monohydric alcohols in yields to ∼50 g/m3 (to a 50% concentration in synthesis water) upon the almost complete conversion of CO. In this case, the fraction of C2-C4 alcohols was as high as 55–60%.