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Carbon Materials (carbon + material)

Distribution by Scientific Domains

Polymers and Materials Science	55%
Chemistry	41%

Selected Abstracts

Investigation of the Effect of Different Glassy Carbon Materials on the Performance of Prussian Blue Based Sensors for Hydrogen Peroxide

ELECTROANALYSIS, Issue 3 2003
Francesco Ricci
Abstract Three different kinds of glassy carbon (GC-R, GC-K, GC-G) were equally pretreated, further modified with electrochemically deposited Prussian Blue and used as sensors for hydrogen peroxide at an applied potential of ,50,mV (vs. Ag|AgCl). Their performance was evaluated with respect to the following parameters: the coverage and electrochemistry of the electrodeposited Prussian Blue, the sensitivity and the lower limit of detection for hydrogen peroxide, and the operational stability of the sensors. GC-R showed the best behavior concerning the surface coverage and the operational stability of the electrodeposited Prussian Blue. For this electrode the sensitivity for hydrogen peroxide (10,,M) was 0.25,A/M cm2 and the detection limit was 0.1,,M. Scanning electron microscopy was used to study the surfaces of the three electrodes before and after the electrodeposition of Prussian Blue and to search for the reason for the three different behaviors between the different glassy carbon materials. The Prussian Blue modified GC-R was also used for the construction of a glucose biosensor based on immobilizing glucose oxidase in Nafion membranes on top of electrodeposited Prussian Blue layer. The operational stability of the glucose biosensors was studied in the flow injection mode at an applied potential of ,50,mV (vs. Ag|AgCl) and alternatively injecting standard solutions of hydrogen peroxide (10,,M) and glucose (1,mM) for 3,h. For the GC-R based biosensor a 2.8% decrease of the initial glucose response was observed. [source]

The Influence of Surface Chemistry and Pore Size on the Adsorption of Proteins on Nanostructured Carbon Materials

ADVANCED FUNCTIONAL MATERIALS, Issue 15 2010
Munusami Vijayaraj
Abstract Carbon films are synthesized by templating of anodic aluminum oxide films. These carbon materials exhibit nanochannels with controlled diameter and length. Selected chemical treatments are done to tailor the surface chemistry. The adsorption capacities of bovine serum albumin and cytochrome c are measured by temperature-programmed desorption with mass spectrometry (TPD-MS) analysis and with conventional biological assays. The first method allows quantification of the proteins that exhibit strong interactions with the surface, while the second one is used to obtain the total adsorption capacity. Moreover, the TPD-MS profiles, which are related to the structural modifications of the proteins during the adsorption, show that strong interactions take place with hydrophobic surfaces. When oxygenated functions are present, the adsorption capacity increases and the nature of the interactions is modified. The ratio of irreversible to reversible adsorption is significantly different for the two proteins, and is slightly related to the surface chemistry. The influence of nanochannel size is studied: below 50 nm, the coverage ratio shows that access to the porosity is limited by diffusion in the channel and by pore plugging, in agreement with the strong interactions of proteins with the carbon surface. [source]

Tuning Carbon Materials for Supercapacitors by Direct Pyrolysis of Seaweeds

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Encarnación Raymundo-Piñero
Abstract The sea provides a large variety of seaweeds that, because of their chemical composition, are fantastic precursors of nanotextured carbons. The carbons are obtained by the simple pyrolysis of the seaweeds under a nitrogen atmosphere between 600 and 900,°C, followed by rinsing the product in slightly acidic water. Depending on the origin of the seaweed and on the pyrolysis conditions, the synthesis may be oriented to give an oxygen-enriched carbon or to give a tuned micro/mesoporous carbon. The samples with a rich oxygenated surface functionality are excellent as supercapacitor electrodes in an aqueous medium whereas the perfectly tuned porous carbons are directly applicable for organic media. In both cases, the specific surface area of the attained carbons does not exceed 1300 m2 g,1, which results in high-density materials. As a consequence, the volumetric capacitance is very high, making these materials more interesting than activated carbons from the point of view of developing small and compact electric power sources. Such versatile carbons, obtained by a simple, ecological, and cheap process, could be well used for environment remediation such as water and air treatment. [source]

Functionalization of Porous Carbon Materials with Designed Pore Architecture,

ADVANCED MATERIALS, Issue 3 2009
Andreas Stein
Abstract Recent progress in syntheses of porous carbons with designed pore architecture has rejuvenated the field of carbon chemistry and promises to provide new advanced materials. In order to reap the full benefit of designer carbons, it is necessary to develop chemistries for functionalizing the porous carbon surfaces. This Review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers. Methods of characterizing the functionalized carbon materials and applications that benefit from functionalized nanoporous carbons with designed architecture are also highlighted. [source]

Nitrogen-Doped Carbon Materials Prepared by Ammoxidation as Solid Base Catalysts for Knoevenagel Condensation and Transesterification Reactions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010
Naokatsu Kan-nari
Abstract Nitrogen-doped carbon materials were prepared by ammoxidation of commercial carbon sources (carbon black and activated carbon) and applied as base catalysts for Knoevenagel and transesterification reactions. It was shown that these carbon materials were active and the activities were different depending on the ammoxidation conditions (temperature and ammonia concentration in air) and carbon sources used. The bulk, textural, and surface properties of the nitrogen-doped carbon materials were examined by several methods to clarify possible factors determining their final catalytic activities. The activated carbon-derived catalysts were more active than the carbon black-derived ones. The surface area and porosity were not responsible for this difference between the two carbon sources but the difference in the reactivity with oxygen was important. The reactivity of carbon sources with oxygen should influence the doping of nitrogen onto their surfaces by ammoxidation with ammonia and air and the resulting activities as base catalysts. The catalytic activity increases with the amount of nitrogen doped and, therefore, the nitrogen doped should be responsible for the catalytic activities. In addition, the activities are maximal at a ratio of nitrogen to oxygen of around 1, suggesting the importance of cooperative functions of nitrogen and oxygen on the surface of carbons. [source]

Microstructure and Thermal Shock Resistance of Molten Glass-Coated Carbon Materials Fabricated by Interfacial Control

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006
Masashi Wada
Carbon substrates were coated completely with a molten silicate glass, where the wettability of carbon to glass was improved by infiltration and pyrolysis of perhydropolysilazane. Microstructures of the carbon,glass interface were dependent on Pn2 during coating. Coating at lower Pn2 induced the formation of cristobalite at the carbon,glass interface. When the coating was performed at higher Pn2, the glass and carbon were strongly adhered, without the formation of cristobalite. Coating at higher Pn2 improved the thermal shock resistance of the glass layer, because crack initiation was not induced by the phase transformation of cristobalite during the cooling process. In the case of coating at higher Pn2, an oxynitride glass layer was formed at the glass subsurface by dissolution of N2. A porous glass subsurface layer with uniform spherical micro-pores could be produced by soaking near the glass transition temperature in a steam environment. The porous layer with fine and homogeneous microstructure acts as a thermal shock absorbing layer, so that glass-coated carbon with a porous glass layer has excellent thermal shock resistance in addition to steam oxidation resistance. [source]

Simple Synthesis of Graphitic Ordered Mesoporous Carbon Materials by a Solid-State Method Using Metal Phthalocyanines,

ANGEWANDTE CHEMIE, Issue 31 2009
Tae Lee Dr.
Kohlenstoff-Vorstufen in Form von Metallphthalocyaninen führen dazu, dass bei einer Pseudo-Festkörper-in-situ-CVD auf mesoporösem Silicat hoch graphitische mesoporöse Kohlenstoffmaterialien (siehe TEM-Bild) mit geordneter Porenstruktur, großer Oberfläche und großem Porenvolumen entstehen. Dieser einfache Syntheseansatz eignet sich für die Produktion größerer Mengen, und die Graphitisierung wird durch die katalytische Wirkung des Metalls verstärkt. [source]

Quantitative Studies of Metal Ion Adsorption on a Chemically Modified Carbon Surface: Adsorption of Cd(II) and Hg(II) on Glutathione Modified Carbon

ELECTROANALYSIS, Issue 8 2009
Poobalasingam Abiman
Abstract The adsorption behavior of model toxic metal cations namely Cd(II) and Hg(II) on carbon surfaces chemically modified by glutathione was investigated as a function of the concentration of Cd2+ and Hg2+ ions, time and the amount of modified carbon used. Square wave and linear sweep anodic stripping voltammetry was used to monitor the uptake of Cd(II) and Hg(II) ions respectively. Kinetic and adsorption isotherm studies reveal that both Cd(II) and Hg(II) ions undergo similar large adsorption with the modified glutathione carbon material (Glu-carbon). [source]

Dangers relating to fires in carbon-fibre based composite material

FIRE AND MATERIALS, Issue 4 2005
Tommy Hertzberg
Abstract Inhalable carbon fibres have been suspected to pose similar threats to human health as asbestos fibres. It is well-known that fibres having a diameter of less than 3 µm might be inhaled and transported deep into the human respiratory system. Some composite materials use carbon fibres as structural reinforcement. These fibres do not pose any risks as such as they are firmly connected to the laminate and surrounded by a polymer matrix. Also, these fibres typically have diameters >6 µm and thus, are not inhalable. However, if the material is exposed to a fire, the carbon material might be oxidized and fractionated and thereby, inhalable fibres might be generated into the fire smoke. The capability of carbon fibre-based composite material to produce dangerous inhalable fibres from different combustion scenarios has been investigated. It was found that the risk of fires generating inhalable carbon fibres is related to the surface temperature, the oxygen level and the airflow field close to the material surface. The temperatures necessary for oxidation of the carbon fibre is so high that it is possible that only a flashover situation will pose any real danger. Other possible danger scenarios are highly intense fires (e.g. a liquid fuel fire), or situations where structural damage is part of the fire scenario. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The Large Electrochemical Capacitance of Microporous Doped Carbon Obtained by Using a Zeolite Template,

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2007
O. Ania
Abstract A novel microporous templated carbon material doped with nitrogen is synthesized by using a two-step nanocasting process using acrylonitrile (AN) and propylene as precursors, and Na,Y zeolite as a scaffold. Liquid-phase impregnation and in,situ polymerization of the nitrogenated precursor inside the nanochannels of the inorganic scaffold, followed by gas-phase impregnation with propylene, enables pore-size control and functionality tuning of the resulting carbon material. The material thereby obtained has a narrow pore-size distribution (PSD), within the micropore range, and a large amount of heteroatoms (i.e., oxygen and nitrogen). In addition, the carbon material inherits the ordered structure of the inorganic host. Such features simultaneously present in the carbon result in it being ideal for use as an electrode in a supercapacitor. Although presenting a moderately developed specific surface area (SBET,=,1680,m2,g,1), the templated carbon material displays a large gravimetric capacitance (340,F,g,1) in aqueous media because of the combined electrochemical activity of the heteroatoms and the accessible porosity. This material can operate at 1.2,V in an aqueous medium with good cycleability,-beyond 10,000,cycles,and is extremely promising for use in the development of high-energy-density supercapacitors. [source]

Synthesis and Catalytic Applications of Self-Assembled Carbon Nanofoams,

ADVANCED MATERIALS, Issue 2 2008
J. García-Martínez
A new surfactant-templated carbon material, carbon nanofoam (CNF), has been synthesized with a semicrystalline and conductive framework, high surface area and interconnected porous structure, and prepared in a wide variety of bulk shapes and forms. CNF was also successfully applied as a support for palladium in the Heck coupling reaction. Pd/CNF catalyst exhibited negligible Pd cluster growth and agglomeration, and retained high activity even after multiple runs. [source]

Investigation of the Effect of Different Glassy Carbon Materials on the Performance of Prussian Blue Based Sensors for Hydrogen Peroxide

The Influence of Surface Chemistry and Pore Size on the Adsorption of Proteins on Nanostructured Carbon Materials

Stable ,Floating' Air Diffusion Biocathode Based on Direct Electron Transfer Reactions Between Carbon Particles and High Redox Potential Laccase

FUEL CELLS, Issue 4 2010
S. Shleev
Abstract We report on the assembly and characterisation of a high potential, stable, mediator-less and cofactor free biocathode based on a fungal laccase (Lc), adsorbed on highly dispersed carbonaceous materials. First, the stability and activity of Trametes hirsuta Lc immobilised on different carbon particles were studied and compared to the solubilised enzyme. Based on the experimental results and a literature analysis, the carbonaceous material BM-4 was chosen to design efficient and stable biocatalysts for the production of a ,floating' air diffusion Lc-based biocathode. Voltammetric characteristics and operational stability of the biocathode were investigated. The current density of oxygen reduction at the motionless biocathode in a quiet, air saturated citrate buffer (100,mM, pH 4.5, 23,°C) reached values as high as 0.3,mA,cm,2 already at 0.7,V versus NHE. The operational stability of the biocathode depended on the current density of the device. For example, at low current density (20,,A,cm,2), the biocathode lost only 5× of its initial power after 1 month of continuous operation. However, when the device was polarised at 150,mV it lost more than 32× of its initial power in just 10,min. We also found that co-immobilisation of Lc and peroxidase on highly dispersed carbon materials could protect the biocatalyst from rapid inactivation by hydrogen peroxide produced during electrocatalytic reactions at high-current densities. [source]

Nitrogen-Enriched Nonporous Carbon Electrodes with Extraordinary Supercapacitance

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Denisa Hulicova-Jurcakova
Abstract Nitrogen-enriched nonporous carbon materials derived from melamine,mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol-like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300,µF,cm,2) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280,F,cm,3 in KOH, 152,F,cm,3 in H2SO4, and 92,F,cm,3 in tetraethylammonium tetrafluoroborate/propylene carbonate. [source]

Replication and Coating of Silica Templates by Hydrothermal Carbonization,

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007
M.-M. Titirici
Abstract Hierarchical carbon materials with functional groups residing at the surface are prepared for the first time by using nanostructured silica materials as templates in combination with hydrothermal carbonization at mild temperatures (180,°C). Different carbon morphologies (e.g., macroporous casts, hollow spheres, carbon nanoparticles, and mesoporous microspheres) can be obtained by simply altering the polarity of the silica surface. The surface functionality and hydrophilicity of the resulting materials are assessed by Fourier transform IR spectroscopy, X-ray photoelectron analysis, and water porosimetry. Raman spectroscopy and X-ray diffraction measurements show that the materials are of the carbon-black type, similar to charcoal. [source]

Functionalization of Porous Carbon Materials with Designed Pore Architecture,

Rational Functionalization of Carbon Nanotubes Leading to Electrochemical Devices with Striking Applications,

ADVANCED MATERIALS, Issue 15 2008
Jie Yan
Abstract As one-dimensional carbon nanostructures, carbon nanotubes (CNTs) are a member of the carbon family but they possess very different structural and electronic properties from other kinds of carbon materials frequently used in electrochemistry, such as glassy carbon, graphite, and diamond. Although the past decade has witnessed rapid and substantial progress in both the fundamental understanding of CNT-oriented electrochemistry and the development of various kinds of electrochemical devices with carbon nanotubes, the increasing demand from both academia and industry requires CNT-based electrochemical devices with vastly improved properties, such as good reliability and durability, and high performance. As we outline here, the smart functionalization of CNTs and effective methods for the preparation of devices would pave the way to CNT-based electronic devices with striking applications. [source]

Nitrogen-Doped Carbon Materials Prepared by Ammoxidation as Solid Base Catalysts for Knoevenagel Condensation and Transesterification Reactions

Hydrogen storage properties of B- and N-doped microporous carbon

AICHE JOURNAL, Issue 7 2009
Lifeng Wang
Abstract A B- and N-doped microporous carbon has been synthesized via a substitution reaction. The obtained carbon exhibited much higher surface area than the previously reported B- and N-doped carbon. The hydrogen storage measurements indicated that the B- and N-doped microporous carbon had a 53% higher storage capacity than the carbon materials with similar surface areas. Furthermore, hydrogen storage via spillover was studied on Ru-supported B- and N-doped microporous carbon and a storage capacity of 1.2 wt % at 298 K and 10 MPa was obtained, showing an enhancement factor of 2.2. Ab initio molecular orbital calculations were also performed for the binding energies between the spiltover hydrogen atom and various sites on the doped carbon. The theoretical calculations can explain the experimental results well, which also shed light on the most favorable and possible sites with which the spiltover hydrogen atoms bind. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

A mechanistic investigation into the covalent chemical derivatisation of graphite and glassy carbon surfaces using aryldiazonium salts

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 6 2008
Poobalasingam Abiman
Abstract Modification of carbon materials such as graphite and glassy carbon in bulk quantities using diazonium salts is developed. We used both 4-nitrobenzenediazonium tetrafluoroborate and 1-antharaquinonediazonium chloride to modify graphite and glassy carbon surfaces. Experiments were carried out in the presence and absence of hypophosphorous acid and the mechanism involved in both cases were studied using cyclic voltammetry. The observed peak potentials for both the 4-nitrophenyl and 1-anthraquinonyl modified materials were found to differ depending on whether or not the hypophosphorous acid reducing agent was used. In the absence of hypophosphorous acid the derivatisation reaction was inferred to go through a cationic intermediate, whilst in the presence of the hypophosphorous acid the mechanism likely involves either a purely radical intermediate or a mixture of radical and cationic species. Derivatisation experiments from 5 to 70°C allowed us to determine the optimum derivatisation temperature for both cases, in the presence and absence of hypophosphorous acid. Optimum temperature was 20°C for the former and 35°C for the later. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Mesoscopic Structure and Properties of Liquid Crystalline Mesophase Pitch and Its Transformation into Carbon Fiber

THE CHEMICAL RECORD, Issue 2 2002
Isao Mochida
Abstract The history and present state of the art in the chemistry of mesophase pitch, which is an important precursor for carbon fiber and other high-performance industrial carbons, are reviewed relative to their structural properties. The structural concepts in both microscopic and macroscopic views are summarized in terms of the sp2 carbon hexagonal plane as a basic unit common to graphitic materials, its planar stacking in clusters, and cluster assembly into microdomains and domains, the latter of which reflect the isochromatic unit of optical anisotropy. Such a series of structural units is described in a semiquantitative manner corresponding to the same units of graphitic materials, although the size and stacking height of the hexagonal planes (graphitic sheets) are very different. Mesophase pitch is a liquid crystal material whose basic structural concepts are maintained in the temperature range of 250 to 350,°C. The melt flow and thermal properties are related to its micro- and mesoscopic structure. The structure of mesophase-pitch,based carbon fiber of high tensile strength, modulus, and thermal conductivity has been formed through spinning, and has inherited the same structural concepts of mesophase pitch. Stabilization settles the structure in successive heat treatments up to 3000,°C. Carbonization and graphitization enable growth of the hexagonal planes and their stacking into units of graphite. Such growth is governed and controlled by the alignment of micro- and mesoscopic structures in the mesophase pitch, which define the derived carbon materials as nanostructural materials. Their properties are controlled by the nanoscopic units that are expected to behave as nanomaterials when appropriately isolated or handled. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2:81,101, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10016 [source]

Enhanced Field Electron Emission Properties of Hybrid Carbon Nanotubes Synthesized by RF-PECVD,

CHEMICAL VAPOR DEPOSITION, Issue 10-12 2009
Guangmin Yang
Abstract In this work, pristine carbon nanotubes (CNTs) are grown in-situ with a variety of carbon allotropes (e.g., carbon nanoonions, nanocones, thin nanotubes, etc.) attached on the surface of the CNTs. The nanostructures of the hybrid carbon materials are characterized with transmission electron microscopy (TEM), and the structural dependence of field electron emission properties was investigated. It is found that the hybrid CNTs exhibit exotic morphologies having excellent field electron emission properties. These findings provide a simple synthesis method to assemble the carbon nanomaterials and a new insight into the fundamental understanding of high-performance CNTs towards applications in field-emission devices. [source]

Special Issue on Carbon Nanotubes

CHEMICAL VAPOR DEPOSITION, Issue 6 2006
L. Terranova
Abstract Carbon Nanotubes are the topic of this Special Issue of Chemical Vapor Deposition. In this introduction, Guest Editor Maria Letizia Terranova highlights the potential of nanostructured carbon materials and comments on the importance of CVD synthesis techniques in this ever- expanding field. [source]

Syntheses and Morphologies of Carbon Microsolenoid Composites and Double Negative Microcoils,

CHEMICAL VAPOR DEPOSITION, Issue 2 2004
S. Yang
Abstract Novel carbon microsolenoid composites with central straight nanopores along the coil axes and double negative microcoils with helically formed nanopores along the fiber axes were prepared by a two-step CVD process using carbon microcoil (CMC) templates. The as-grown CMC templates were synthesized at 780,°C, and the pyrolytic carbon layer (Py-C) was coated in-situ at 860,°C on the surface, then the core CMCs were preferentially oxidized at 700,°C for 10,min in air. In the carbon microsolenoids, the straight, central nanopores, with a diameter of 0,600,nm, were derived from the central pores existing along the coil axis of the source, regularly-coiled CMC templates, while the double negative microcoils were derived from the burnt-out core CMC templates in the carbon microsolenoids. The morphology and microstructure of the novel carbon materials were observed and analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry (TG), and X-ray diffraction (XRD). [source]

Investigation of Hydrogen Physisorption Active Sites on the Surface of Porous Carbonaceous Materials

CHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2008
Deyang Qu
Abstract Hydrogen physisorption in different carbonaceous materials was investigated in liquid nitrogen (77,K). The total hydrogen adsorption was found to have a linear relationship with the surface area of pores <30,Å. The surface area and porosity of the carbon materials were determined by dinitrogen adsorption at 77,K and density function theory (DFT). The active sites for hydrogen adsorption were investigated and found to be related to the edge orientation of defective graphene micro-sheet domains. [source]