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  Subjects -> CHEMISTRY (Total: 845 journals)
    - ANALYTICAL CHEMISTRY (51 journals)
    - CHEMISTRY (595 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
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    - PHYSICAL CHEMISTRY (67 journals)

CHEMISTRY (595 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 8)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 34)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 18)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 24)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 244)
ACS Photonics     Full-text available via subscription   (Followers: 11)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 56)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 15)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 21)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 27)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 14)
Analyst     Full-text available via subscription   (Followers: 40)
Angewandte Chemie     Hybrid Journal   (Followers: 203)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 219)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 310)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 118)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 91)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 4)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 66)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 8)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 14)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 72)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 24)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 20)
Chemical Reviews     Full-text available via subscription   (Followers: 183)
Chemical Science     Open Access   (Followers: 22)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 58)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 26)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 146)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 258)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 9)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 17)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 61)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 3)
Environmental Chemistry     Hybrid Journal   (Followers: 7)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)

        1 2 3 | Last

Journal Cover Carbon
  [SJR: 2.109]   [H-I: 194]   [66 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6223
   Published by Elsevier Homepage  [3051 journals]
  • Graphene-decorated carbon-coated LiFePO4 nanospheres as a high-performance
           cathode material for lithium-ion batteries
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Xufeng Wang, Zhijun Feng, Juntong Huang, Wen Deng, Xibao Li, Huasen Zhang, Zhenhai Wen
      Nanohybrids of graphene-decorated carbon-coated LiFePO4 nanospheres are prepared using a ball milling-assisted rheological phase method combined with a solid-state reaction. The hybrids are characterized by XRD, SEM, TEM, HRTEM, XPS, Raman and TGA, and their electrochemical properties are studied by CV, EIS and galvanostatic charge-discharge. The experimental results exhibit that multilayer graphene films are decorating carbon-coated LiFePO4 nanospheres without stacking, which results in an abundance of mesopores constituting a unique 3D “sheets-in-pellets” and “pellets-on-sheets” conducting network structure. This structure highlights the improvements of the rate and cyclic performance as a cathode material for lithium-ion batteries, because the highly conductive and plentiful mesopores promote electronic and ionic transport. As a result, the hybrids with approximately 3 wt% graphene exhibit an outstanding rate capability with an initial discharge capacity of 163.8 and 147.1 mA h g−1 at 0.1 C and 1 C, and the capacity is retained at 81.2 mA h g−1 even at 20 C. Moreover, the composites also reveal an excellent cycling stability with only an 8% capacity decay at 10 C after 500 cycles.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Beyond the classical kinetic model for chronic graphite oxidation by
           moisture in high temperature gas-cooled reactors
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Cristian I. Contescu, Robert W. Mee, Yoonjo (Jo Jo) Lee, José D. Arregui-Mena, Nidia C. Gallego, Timothy D. Burchell, Joshua J. Kane, William E. Windes
      Four grades of nuclear graphite were oxidized in helium with traces of moisture and hydrogen in order to evaluate the effects of slow oxidation by moisture on graphite components in high temperature gas cooled reactors. Kinetic analysis showed that the Langmuir-Hinshelwood (LH) model cannot consistently reproduce all results. In particular, at high temperatures and water partial pressures, oxidation was always faster than the LH model predicts. It was also found empirically that the apparent reaction order for water has a sigmoid-type variation with temperature which follows the integral Boltzmann distribution function. This suggests deviations from the LH model are apparently caused by activation with temperature of graphite reactive sites, which is probably rooted in specific structural and electronic properties of graphite. A semi-global kinetic model was proposed, whereby the classical LH model was modified with a temperature-dependent reaction order for water. This new Boltzmann-enhanced Langmuir-Hinshelwood (BLH) model consistently predicts oxidation rates over large ranges of temperature (800–1100 °C) and partial pressures of water (3–1200 Pa) and hydrogen (0–300 Pa). The BLH model can be used for modeling chronic oxidation of graphite components during life-time operation in high- and very high temperature advanced nuclear reactors.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Luminescent hybrid materials based on nanodiamonds
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Dongxue Zhang, Qi Zhao, Jinhao Zang, Ying-Jie Lu, Lin Dong, Chong-Xin Shan
      Luminescent hybrid materials were prepared by covalently functionalizing nanodiamonds (NDs) with rare earth (RE) complexes. Pyromellitic acid (PMA), as the organic sensitizer, was grafted onto amino-terminated NDs to chelate lanthanide ions (Eu3+ and Tb3+). The emission colors of the hybrid composite of ND-PMA-Eu x Tb y can be tuned from red to orange, yellow and green by adjusting the molar ratio of Eu3+ to Tb3+. Moreover, the luminescence of the hybrid composites exhibits remarkable photostability under ultraviolet irradiation for 60 h. As a proof-of-concept experiment, the as-synthesized ND-PMA-Eu and ND-PMA-Tb were employed as the phosphors for red and green light-emitting-diode (LED) devices with ultraviolet (UV) chips. Therefore, the nanodiamond-based luminescent hybrid material may find potential application in optical device.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Interfacial structure in AZ91 alloy composites reinforced by graphene
           nanosheets
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Qiu-hong Yuan, Guo-hua Zhou, Lin Liao, Yong Liu, Lan Luo
      Graphene nanosheets (GNS) are the promising nano-reinforcements to fabricate bulk graphene-metal composites due to their excellent mechanical properties and large yield. However, the effective synthesis of such bulk graphene reinforced magnesium (Mg) composites remains challenging because of the poor interfacial bonding and the aggregation of GNS. Here, GNS possessing about 12 at. % residual oxygen (∼7:1 C/O ratio) was synthesized by a thermal reduction method. These residual oxygen in GNS is beneficial to increase the interfacial bonding between GNS and the matrix of α-Mg by MgO nanoparticles, which synthesized through the occurrence of a reaction between the residual oxygen and α-Mg in the composites. TEM analysis reveals that the in-situ synthesized MgO nanoparticles can significantly improve the interfacial bonding between GNS and α-Mg owing to the formation of semi-coherent interface of MgO/α-Mg and the distortion area bonding interface of GNS/MgO. By filling 0.5 wt. % of GNS, the yield strength and elongation of the composite increased by 76.2% and 24.3%, respectively as compared to the matrix alloy. The significant improvement in mechanical properties of the composites is mainly due to the grain refinement, strong interfacial bonding and dislocation strengthening.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Adiabatic control of surface plasmon-polaritons in a 3-layers graphene
           curved configuration
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Wei Huang, Shi-Jun Liang, Elica Kyoseva, Lay Kee Ang
      In this paper, we utilize coupled mode theory (CMT) to model the coupling between surface plasmon-polaritons (SPPs) between multiple graphene sheets. By using the Stimulated Raman Adiabatic Passage (STIRAP) Quantum Control Technique, we propose a novel directional coupler based on SPPs evolution in three layers of graphene sheets in some curved configuration. Our calculated results show that the SPPs can be transferred efficiently from the input graphene sheet to the output graphene sheet, and the coupling is also robust that it is not sensitive to the length of the device configuration's parameters and excited SPPs wavelength.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Plasma modification of vertically aligned carbon nanotubes:
           Superhydrophobic surfaces with ultra-low reflectance
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Christopher S. Yung, Nathan A. Tomlin, Karl Heuerman, Mark W. Keller, Malcolm G. White, Michelle Stephens, John H. Lehman
      Vertically aligned carbon nanotubes (VACNTs) are excellent broadband (UV–VIS–IR) absorbers of light that can be made even darker with plasma treatments. Modification of VACNTs using O2 and/or CF4 plasmas is shown to have a significant impact on the reflectance and water repellency. Unfortunately, while O2 plasma treatment reduces the reflectance of VACNTs by changing the top surface morphology, it also makes the VACNTs superhydrophilic. Using an additional CF4 plasma treatment, we show that low reflectance and superhydrophobic surfaces are possible — qualities that are desirable when utilizing VACNTs as black body absorbers in cryogenic environments due to the potential for adsorbed water or ice. Using scanning electron microscopy we show that both plasma treatments can change the surface morphology of the VACNTs similarly, which is associated with a corresponding measured reduction in spectral reflectance. Raman spectroscopy of as-grown and plasma treated samples suggest that plasma treatment is introducing defects and functionalizing the nanotube walls and thereby affecting the water repellency. O2 plasma treated VACNTs have a directional-hemispherical reflectance (d/h) at normal incidence (d = 0°) of 94 ± 4 ppm (with a coverage factor of k = 2) at 660 nm and are superhydrophilic. O2 and CF4 plasma treated VACNTs have a 0°/h reflectance of 163 ± 7 ppm (k = 2) at 660 nm and are superhydrophobic with a contact angle of 159°.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Comment on “Carbon structure in nanodiamonds elucidated from Raman
           spectroscopy” by V.I. Korepanov et al.
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): V.Yu. Osipov, A.M. Panich, A.V. Baranov
      In the recent study, V.I. Korepanov et al. [1] reported on Raman spectroscopy study of the structure of nanodiamonds. They claimed that the Raman spectroscopy provides unique quantitative tool for nanodiamond characterization and determination of the relative content of carbon atoms belonging to the diamond core, disordered shell and graphene-like phases. There are several issues in this research that we must comment on.

      PubDate: 2017-11-16T03:18:13Z
       
  • Chemical reduction dependent dielectric properties and dielectric loss
           mechanism of reduced graphene oxide
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Boya Kuang, Weili Song, Mingqiang Ning, Jingbo Li, Zhengjing Zhao, Deyu Guo, Maosheng Cao, Haibo Jin
      Reduced Graphene Oxide (rGO) is expected to be the most promising candidate for high-efficiency electromagnetic wave absorption materials. However, its defect-related dielectric loss mechanism has not been clarified up to date, especially when it comes to the pure rGO system. Here, the rGO with controllable reduction degree is prepared. The oxygen-containing functional groups are regularly removed from rGO during reduction. Accompanying with the decrease of oxygen-containing functional groups, the content of lattice-defects in rGO is increased with increasing reduction degree of rGO. The dielectric and microwave absorption properties of rGO with different reduction degrees are investigated over 2–18 GHz. Compared to the GO, rGO exhibits obvious dielectric relaxation behaviors with a relaxation peak at ∼10 GHz. The dielectric relaxation of rGO is enhanced by increasing reduction degree of rGO. The experimental results evidence that the enhanced dielectric relaxation behavior originates from the increased vacancy defect dipoles in rGO generated through chemical reduction, and rule out the contribution of oxygen-containing functional groups to the dielectric relaxation. This work reveals the mechanism of defect-related dielectric relaxation of rGO, which may contribute to the correct understanding of dielectric loss of carbon-based materials for designing and/or modifying carbon-based microwave attenuation materials.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Self-assembly of phenoxyl-dextran on electrochemically reduced graphene
           oxide for nonenzymatic biosensing of glucose
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Bo Li, Aimin Yu, Guosong Lai
      Electrochemically reduced graphene oxide (ERGO) has attracted considerable interest in the electrochemical biosensing field. In this work, the π−π stacking assembly of phenoxyl-dextran (DexP) and sensitive electrochemical stripping analysis of gold nanoparticles (Au NPs) on the ERGO surface are conducted to develop a novel nonenzymatic glucose biosensing method. Concanavalin A (Con A) was covalently linked with Au NP to obtain a nanoprobe, which was used for the specific biorecognition of glucose at the ERGO/DexP biosensor. Based on the glucose-Con A-dextran competition reaction, the Au NP/Con A nanoprobes were quantitatively captured onto the biosensor surface. Through the electrochemical stripping analysis of Au NPs, sensitive signal transduction was achieved. ERGO not only enables the simple preparation of the biosensor but also improves the sensitivity of the method greatly. The high specificity of the Con A biorecognition and the relatively positive potential range for the gold stripping analysis exclude well the signal interferences involving in the conventional electrochemical glucose biosensors. Thus such a nonenzymatic glucose biosensing method featuring excellent performance, low cost and convenient signal transduction provides a great potential for the diabetes diagnosis application.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Robust, hydrophilic graphene/cellulose nanocrystal fiber-based electrode
           with high capacitive performance and conductivity
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Guoyin Chen, Tao Chen, Kai Hou, Wujun Ma, Mike Tebyetekerwa, Yanhua Cheng, Wei Weng, Meifang Zhu
      Graphene fiber-based electrodes for supercapacitors are promising candidates for wearable energy storage. Their main limitation, although, is the low electrochemical performance caused by the restacking of graphene sheets and their hydrophobicity to electrolytes. Incorporation of nanofillers into graphene is an efficient way to overcome the challenges, however, often leading to a severe deterioration in their mechanical property and/or conductivity, thus significantly influences the practical applications and rate performance of the device. Herein, an approach of fabricating hybrid fibers from graphene oxide (GO) and cellulose nanocrystal (CNC) via non-liquid-crystal spinning and followed by chemical reduction is presented to collectively work around the problems. The resultant hybrid GO/CNC fibers demonstrated a high capacitive performance, enhanced mechanical property, and improved hydrophilicity simultaneously. Furthermore, the conductivity kept at a high value. Sample with a GO/CNC weight ratio of 100/20 possessed a high capacitance of 208.2 F cm−3, a strength of 199.8 MPa, a contact angle of 63.3°, and conductivity of 64.7 S cm−1. Moreover, the supercapacitor assembled from this fiber exhibited a high energy density and power density (5.1 mW h cm−3 and 496.4 mW cm−3), excellent flexibility and bending stability, which has a great potential for use as a flexible power storage.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Hexagonal rotator order of bound ionic surfactants and temperature
           triggered dispersion of carbon nanotubes
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Mario Maggio, Rosamaria Marrazzo, Maria Rosaria Acocella, Veronica Granata, Gaetano Guerra
      Oxidized Carbon Nanotubes (CNT) form stable adducts with ammonium ions exhibiting long alkyl chains. Outer surfaces of CNT adducts are completely covered by hydrocarbon tails, which spontaneously organize in hexagonal rotator order, with 1 hydrocarbon tail per 8 graphitic carbon atoms of the external CNT wall. Order-disorder transitions, which involve loss of packing and of zig-zag planar conformation of the bound hydrocarbon tails, occur by heating at temperatures not far from room temperature and lead to temperature-triggered dispersion in organic media of the CNT adducts. CNT adduct formation is reversible with pH changes, as clearly shown by reversible moving of CNT between apolar and polar immiscible phases.
      Graphical abstract image

      PubDate: 2017-11-16T03:18:13Z
       
  • Mechanically robust and highly compressible electrochemical
           supercapacitors from nitrogen-doped carbon aerogels
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Xiaofang Zhang, Jiangqi Zhao, Xu He, Qingye Li, Chenghong Ao, Tian Xia, Wei Zhang, Canhui Lu, Yulin Deng
      Macroscopic, free-standing and flexible three dimensional porous carbon aerogel holds great potential for supercapacitor design but is often hindered by their inherent hydrophobicity, structure-derived fatigue failure and weak elasticity. In this study, a strong and flexible nitrogen-doped carbon aerogel is prepared by direct pyrolysis of bamboo cellulose nanofibers /melamine/graphene oxide hybrid aerogel, which features the characteristics of being catalyst-free, cost-effective and of small environmental footprint. The obtained monolithic carbon aerogel is constructed by welding amorphous carbon nanofibers and graphene nanoplatelets together into a hierarchical carbon-graphene architecture, demonstrating outstanding microstructure-derived resilience and mechanical strength. It is capable to undergo at least 40% reversible compressive deformation and the maximum compressive strength reaches 29.3 kPa. Impressively, due to the unique carbon-graphene architecture together with the hydrophilicity resulted from nitrogen-doping, the carbon aerogel exhibits an excellent specific capacitance of 225 F/g at a current density of 0.25 A/g as well as high energy and power densities of 31.25 Wh kg−1 and 12.9 kW kg−1, respectively. Furthermore, after 100 compression-release cycles, the fully recovered carbon aerogel still maintains great capacitive performances, indicating its superior mechanical durability and electrochemical stability.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Multi-functionalization of GO with multi-cationic ILs as high efficient
           metal-free catalyst for CO2 cycloaddition under mild conditions
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Dong-Hui Lan, Yan-Xi Gong, Nian-Yuan Tan, Shui-Sheng Wu, Jing Shen, Kui-Cheng Yao, Bing Yi, Chak-Tong Au, Shuang-Feng Yin
      To optimize the synergistic effects among hydrogen bond donors, halogen anions and basic sites, we synthesized a series of graphene oxide (GO) materials multi-functionalized with silanol group, multi-cationic quaternary ammonium salt and tertiary amine in a one-pot approach. Hexamethylenetetramine which is cheap and rich with tertiary amine was used as precursor. As characterized by elemental analysis and X-ray photoelectron spectroscopy, the loading of quaternary ammonium salt and tertiary amine was up to 2.56 and 1.84 mmol/g, respectively. This is the first time that a multi-functionalized GO (MF-GO) enriched with multi-cationic quaternary ammonium salt was prepared and used for the cycloaddition of CO2 towards epoxides under mild conditions (90 °C, 2 MPa and 4 h) with high efficiency (TOF = 46.1 h−1) without the need of a solvent and a co-catalyst. The advantage of the combined use of the “multi-cationic approach” and “multi-synergetic strategy” was illustrated by comparing the performance of MF-GO with those of the GO samples that are endowed with different functional groups. A plausible mechanism is proposed for the cycloaddition reaction over MF-GO. Moreover, the MF-GO catalyst can be easily separated and reused for at least five times without significant loss of activity.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Investigation of dispersion behavior of GO modified by different water
           reducing agents in cement pore solution
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Li Zhao, Xinli Guo, Yuanyuan Liu, Chuang Ge, Zhongtao Chen, Liping Guo, Xin Shu, Jiaping Liu
      Graphene oxide (GO) is an attractive candidate for use as a nano-reinforcement in cement composites. However, a prerequisite for GO to fulfill its function is the uniform dispersion of GO throughout the cement matrix. In this paper, the dispersion behavior of GO modified by lignosulfonate (LS), polycondensate of β-naphthalene sulfonate formaldehyde (PNS), and polycarboxylate superplasticizer (PC) in cement pore solution was investigated by a combination of visual observation, optical microscopy and transmission electron microscopy (TEM). Results show that GO modified by PC exhibited better dispersion in cement pore solution than LS and PNS. Zeta potential analysis demonstrated that LS and PNS failed to adsorb onto the GO surface when pH > 11, while successful attachment of PC to GO was achieved even in the alkaline environment. The dispersion mechanisms of PC modified GO were thought to be a combination of covering the surface of GO, lowering the free Ca2+ concentration and impeding the cross-linking of Ca2+ due to steric hindrance effect of PC. With the addition of PC modified GO, the fluidity and mechanical strength of cement composites were improved significantly, indicating that this dispersion route can be successfully used for the preparation of GO reinforced cement composites.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Monolayer graphene doping and strain dynamics induced by thermal
           treatments in controlled atmosphere
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): A. Armano, G. Buscarino, M. Cannas, F.M. Gelardi, F. Giannazzo, E. Schilirò, S. Agnello
      Time dynamics of doping and strain induced in single layer graphene by thermal treatments up to 300°C in vacuum, nitrogen, carbon dioxide and oxygen controlled atmosphere are deeply studied by Raman spectroscopy and they are compared with its morphological evolution investigated by Atomic Force Microscopy. The reaction dynamics in oxygen treatments is determined down to a time scale of few minutes as well as that of dedoping process made by water vapor treatment. The interplay of strain modification and doping effects is separated. The strain is clarified to be strongly influenced by the cooling time. The doping removal is dominated by the water vapor, showing that the concentration of molecular water in gas phase governs the process rate. The opportune choice of heating/cooling and atmosphere enables to tune selectively the strain or doping.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Insights on the mechanism of water-alcohol separation in multilayer
           graphene oxide membranes: Entropic versus enthalpic factors
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Daiane Damasceno Borges, Cristiano F. Woellner, Pedro A.S. Autreto, Douglas S. Galvao
      Experimental evidence has shown that graphene oxide (GO) can be impermeable to liquids, vapors and gases, while it allows a fast permeation of water molecules. Theoretical studies to understand the filtration mechanisms come mostly from water desalination, while very few works have been dedicated to alcohol dehydration. In this work, we have investigated the molecular level mechanism underlying the alcohol/water separation inside GO membranes. A series of Molecular Dynamics and Grand-Canonical Monte Carlo simulations were carried out to probe the ethanol/water and methanol/water separation through GO membranes composed of multiple layered graphene-based films with different interlayer distance values and number of oxygen-containing functional groups. Our results show that the size exclusion and membrane affinities are not sufficient to explain the selectivity. Besides that, the favorable water molecular arrangement inside GO 2D-channels forming a robust H-bond network and the fast water permeation are crucial for an effective separation mechanism. In other words, the separation phenomenon is not only governed by membrane affinities (enthalpic mechanisms) but mainly by the geometry and size factors (entropic mechanisms). Our findings are consistent with the available experimental data and contribute to clarify important aspects of the separation behavior of confined alcohol/water in GO membranes.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Visible light laser-induced graphene from phenolic resin: A new approach
           for directly writing graphene-based electrochemical devices on various
           substrates
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Zhuchan Zhang, Mengmeng Song, Junxing Hao, Kangbing Wu, Chunya Li, Chengguo Hu
      The cost-effective construction of self-designed conductive graphene patterns on desired substrates is crucial to the fabrication of graphene-based electrochemical devices. Here, we report a new approach for the scalable construction of laser-induced graphene (LIG) patterns on diverse substrates by using phenolic resin (PR) as the precursor. The PR-based LIG, which was produced with smart and inexpensive 405 nm semiconductor lasers under ambient conditions, possesses several interesting properties, e.g., 3D porous structures, low resistance (∼44 Ω/sq), good mechanical property and a wide range of applicable substrates, e.g., polymer films, glass slides, metal foils, ceramic plates and plant leaves. The efficient absorption of laser light by PR coatings themselves or dopants such as metal salts and organic dyes is demonstrated critical to the formation of PR-based LIG by visible light lasers. Based on this technique, self-designed and highly conductive graphene arrays can be easily constructed on various substrates to fabricate all-carbon supercapacitors and electrochemical glucose biosensors. The unique properties of PR materials, including easy synthesis, tunable structure and composition, excellent film-formation ability and extremely low cost, thus foresee the promising applications of PR-based LIG in electrochemical fields.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Carbon layer-exfoliated, wettability-enhanced, SO3H-functionalized carbon
           paper: A superior positive electrode for vanadium redox flow battery
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Zhangxing He, Yingqiao Jiang, Yuehua Li, Jing Zhu, Huizhu Zhou, Wei Meng, Ling Wang, Lei Dai
      In this paper, carbon paper as positive electrode for vanadium redox flow battery was etched by chlorosulfonic acid with assistance of ultrasonication. Carbon layer-exfoliated, wettability-enhanced, SO3H-functionalized carbon paper was successfully achieved by facile treatment. The electrochemical kinetics of VO2+/VO2 + redox reaction on carbon paper was significantly improved after the treatment. Carbon paper after ultrasonication-assisted treatment exhibits better electrochemical activity compared with the untreated and only-soaking samples. The cell using treated carbon paper as positive electrode shows larger discharge capacity and higher energy efficiency compared with the pristine cell. The initial discharge capacity of the cell using optimal treated carbon paper reaches 127.7 mA h, 20.8 mA h larger than that of the pristine one at 50 mA cm−2. Furthermore, the average energy efficiency increases by 5.1% by using the treated electrode. The introduced sulfonic groups as active sites and increased surface area by etching can reduce the electrochemical polarization of VO2+/VO2 + redox reaction. Moreover, the improved wettability of treated carbon paper can accelerate mass transfer of active species. Therefore, the reduced electrochemical polarization and accelerated mass transfer of active species conjointly cause the enhanced electrochemical properties of the treated carbon paper.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Defect-mediated, thermally-activated encapsulation of metals at the
           surface of graphite
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Yinghui Zhou, Ann Lii-Rosales, Minsung Kim, Mark Wallingford, Dapeng Jing, Michael C. Tringides, Cai-Zhuang Wang, Patricia A. Thiel
      We show that 3 metals – Dy, Ru, and Cu – can form multilayer intercalated (encapsulated) islands at the graphite (0001) surface if 2 specific conditions are met: Defects are introduced on the graphite terraces to act as entry portals, and the metal deposition temperature is well above ambient. Focusing on Dy as a prototype, we show that surface encapsulation is much different than bulk intercalation, because the encapsulated metal takes the form of bulk-like rafts of multilayer Dy, rather than the dilute, single-layer structure known for the bulk compound. Carbon-covered metallic rafts even form for relatively unreactive metals (Ru and Cu) which have no known bulk intercalation compound.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Raman spectroscopy revealing noble gas adsorption on single-walled carbon
           nanotube bundles
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Renato Cunha, Ricardo Paupitz, Kichul Yoon, Adri C.T. Van Duin, Ana Laura Elías, Victor Carozo, Archi Dasgupta, Kazunori Fujisawa, Néstor Perea Lopez, Paulo T. Araujo, Mauricio Terrones
      The interaction of the noble atoms (Ar and Xe) with single-walled carbon nanotube (SWCNT) bundles are investigated using Raman spectroscopy in conjunction with computational modeling known as ReaxFF force field. SWCNT bundles were deposited on transmission electron microscopy (TEM) grids, and different noble gases were adsorbed onto the nanotubes at 20 K. Raman spectra acquired show significant frequency blueshifts of the radial breathing mode (RBM), G- and G′(or 2D)-bands due to gas solidification within the external groove sites (free spaces between the tubes in the bundle) and external surfaces of the bundles. This solid shell formed by the adsorbed gases contributes with a hydrostatic pressure to the system. We show from Raman measurements that the frequencies found after gas adsorption exhibit almost the same shifts indicating that the interactions between SWCNTs bundles and the gases (Ar or Xe) are nearly identical.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Preparation mechanism of hierarchical layered structure of graphene/copper
           composite with ultrahigh tensile strength
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Ziyue Yang, Lidong Wang, Zhendong Shi, Miao Wang, Ye Cui, Bing Wei, Shichong Xu, Yunpeng Zhu, Weidong Fei
      Nacre-like composite is promising to realize the intriguing properties of graphene in metal matrix. However, how to fabricate the composite with nacre-like structure and improve effectively its property is still challenging. Here we report a facile synthesis of reduced graphene oxide(RGO)/copper(Cu) composite with hierarchical layered structure based on molecular level mixing and self-assembly. The effects of pH value, temperature, mixing method and graphene content on the microstructure and mechanical property of composite were investigated. The pH value and temperature are the main factors in the formation of hierarchical layered structure. For macroscale microstructure, the composites consist of parallel carbon-rich strip aggregates and carbon-poor matrix. For microscale microstructure, the carbon-rich aggregate contains many micro-layered grains composing of alternating layers of graphene and copper, forming a nacre-like composite structure. Furthermore, it is believed that the length-width ratio of macroscopic aggregates related with the mixing method has a significant impact on the mechanical properties of composites. The tensile strength of the 2.5 vol% RGO/Cu composite is as high as 748 MPa. Moreover, good electrical conductivity is also obtained in the composites. This work provides a better understanding of design graphene based composites with hierarchical layered structure and high performance.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Electrochemically generated green-fluorescent N-doped carbon quantum dots
           for facile monitoring alkaline phosphatase activity based on the
           Fe3+-mediating ON-OFF-ON-OFF fluorescence principle
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Fushuang Niu, Yi-Lun Ying, Xin Hua, Yusheng Niu, Yuanhong Xu, Yi-Tao Long
      Herein, green-fluorescent N-doped carbon quantum dots (N-CQDs) with quantum yield of 30.6% were prepared via a simple bottom-up electrochemical (EC) method using the mixtures of pyrocatechol and ethylenediamine as both precursors and electrolytes. The ON-OFF fluorescence (FL) principle that the FL intensity of the N-CQDs was quenched in the presence of Fe3+ was further extended to the ON-OFF-ON and ON-OFF-ON-OFF ones for pyrophosphate anions (PPi) and alkaline phosphatase (ALP) detection, respectively, based on the specific competitive interaction of N-CQDs with Fe3+ and PPi and the hydrolysis of PPi in the presence ALP. Under the optimized conditions, limit of detection (LOD) of 1.2 μM and 0.5 μM were achieved for assays of Fe3+ and PPi, respectively. Meanwhile, measurable evaluation of ALP activity was reached in a wide range from 5 to 360 U/L with a LOD of 1.1 U/L. The as-proposed sensors showed many advantages including label free, rapid, simple, low-cost, high sensitive, which has great promising application potential in vivo and in vitro clinical diagnosis and will promote the application of EC derived carbon nanomaterials.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Carbons for wearable devices - Commentary and introduction to the virtual
           special issue
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Yuan Chen, Liming Dai, Yutaka Ohno


      PubDate: 2017-11-16T03:18:13Z
       
  • Fe-N-doped porous carbon from petroleum asphalt for highly efficient
           oxygen reduction reaction
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Jingyan Liu, Yang Liu, Peng Li, Luhai Wang, Haoran Zhang, Hui Liu, Jialiang Liu, Yixian Wang, Wei Tian, Xiaobo Wang, Zhongtao Li, Mingbo Wu
      Fe-N-doped porous carbon derived from petroleum asphalt (NPCA) was prepared via a facile template synthesis method, with urea as nitrogen source while α-Fe2O3 nanoparticles as template and Fe source. The as-prepared NPCA calcined at 900 °C (NPCA-900) exhibits excellent electrocatalytic performance with high diffusion-limiting current density and stability comparable to those of commercial Pt/C catalysts in alkaline environment. The remarkable ORR performance of NPCA could be ascribed to the abundant porosity, large specific surface area (1060 m2 g−1), as well as the doping of Fe-N (especially pyridinic N). The NPCA derived from cheap petroleum asphalt has good application future in the field of catalysis, while it may pave a new way to realize the clean and high value utilization of heavy oils.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Nitrogen and sulfur dual-doped carbon films as flexible free-standing
           anodes for Li-ion and Na-ion batteries
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Jiafeng Ruan, Tao Yuan, Yuepeng Pang, Sainan Luo, Chengxin Peng, Junhe Yang, Shiyou Zheng
      Heteroatom doping is considered to be one of the most effective approaches to improve the electrochemical activity of carbon-based electrode materials for both Li-ion batteries (LIBs) and Na-ion batteries (SIBs) due to introduction of unbalanced electron atmosphere and enlarged interlayers of carbon materials. Here, we present nitrogen and sulfur dual-doped flexible carbon (NSC) film as a promising free-standing anode for stable high-power and high-energy LIBs or SIBs. The NSC film delivers high reversible capacities of 965.7 mAh g−1 in LIBs and 520.1 mAh g−1 in SIBs at a current density of 100 mA g−1. Particularly, the film electrodes exhibit excellent high-rate capability and remarkable long-term cyclability. For instance, as a LIBs anode, the NSC film remained a high capacity of 357.2 mAh g−1 at 2.0 A g−1 (∼10 min to full charge) after 2000 cycles; even in SIBs, a capacity of 155 mAh g−1 can also be reached at 1.0 A g−1. It is believed that the interconnected conducting structure of carbon backbones, heteroatomic defects and increased carbon interlayers distance by stable SC and NC bonds are beneficial to ultrafast ion diffusion and electron transport, making the NSC film become a high performance free-standing anode for LIBs or SIBs application.
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      PubDate: 2017-11-16T03:18:13Z
       
  • Extenuated interlayer scattering in double-layered graphene/hexagonal
           boron nitride heterostructure
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Nikhil Jain, Fan Yang, Robin B. Jacobs-Gedrim, Xu Xu, M.P. Anantram, Bin Yu
      Interlayer carrier scattering hampers electrical conduction in two-dimensional layered nanostructures. Extenuated carrier scattering is observed in a double-layered graphene system with hexagonal boron nitride (h-BN) as an interposer. Raman spectrum shows signature peaks with enhanced sharpness as compared with that of bilayer graphene. The density functional theory simulation shows degenerate energy bands in the E-k dispersion. The decoupling of the two graphene monolayers is further confirmed by electrical conduction measurements. Improved carrier mobility is observed in the graphene/h-BN/graphene heterostructure as compared with exfoliated or randomly-stacked graphene bilayer, indicating preserved Fermi velocity. The demonstrated behavior in graphene/h-BN/graphene heterostructure suggests a pathway to preserve the excellent carrier transport of pristine graphene monolayer in a multi-channel configuration, leading to implementation of highly conductive 2D heterostructure systems.
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      PubDate: 2017-11-16T03:18:13Z
       
  • A catalytic, catalyst-free, and roll-to-roll production of graphene via
           chemical vapor deposition: Low temperature growth
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Samira Naghdi, Kyong Yop Rhee, Soo Jin Park
      The application of graphene as a two-dimensional nano-material has gained wide interest in different research areas, but its use is still novel for scientists. There has been continuous progress in the development of different synthesis methods to readily produce graphene at a lower cost. Chemical vapor deposition (CVD) is a powerful process to produce graphene, and it is accompanied by other methods. The present article provides a detailed review of the synthesis of graphene by a CVD process at temperatures below 1000 °C (LTCVD). In this work, challenges related to the use of plasma-assisted CVD, different carbon precursors, and catalysts are discussed.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Analysis of acoustical performance of Bi-layer graphene and
           graphene-foam-based thermoacoustic sound generating devices
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Kyoung-Ryul Lee, Sung Hwan Jang, Inhwa Jung
      The objective of this paper is to investigate the acoustical performance of thermoacoustic sound generating devices made of bi-layer graphene and graphene foam. Bi-layer graphene and graphene foam were synthesized using chemical vapor deposition and characterized using HR Raman, X-ray photoelectron spectra, and FE-SEM. The sounds generated by the thermoacoustic devices are measured using a microphone in a semi-anechoic chamber, and frequency spectrums are calculated using a spectrum analyzer. The effects of the input frequency, the voltage of the AC source, and the addition of DC offset on total sound pressure levels have been studied. In particular, the frequency spectra of the generated sounds, which are related to tone quality, are investigated. Compared with the bi-layer graphene thermoacoustic device, the graphene foam thermoacoustic device generated louder sound at low voltage. Additionally, the spectrum of sound generated by the graphene foam thermoacoustic device was clearly different from the spectrum of sound generated by the bi-layer graphene device. The difference in acoustical performance between the thermoacoustic devices made of bi-layer graphene and graphene foam should be considered when developing graphene-based speakers.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Formation mechanism for oxidation synthesis of carbon nanomaterials and
           detonation process for core-shell structure
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Boyang Liu, Shuyu Ke, Yingfeng Shao, Dechang Jia, Chunhua Fan, Fuhua Zhang, Runhua Fan
      A novel formation mechanism according to the oxidative dehydrogenation of organics has been proposed for the low-temperature preparation of carbon-based nanomaterials. Several typical organics including ethanol, 1-butanol, p-cymene and liquid paraffin are used as precursors to react with ammonium persulfate (APS) in an autoclave, and carbon particles are obtained as a validation. The reaction characteristics are comprehensively investigated by the differential scanning calorimetric and thermogravimetric analysis. The strongly exothermic oxidation reaction below 200 °C is a common feature during the process. The organic molecules are cleaved into small carbon species and further transform to amorphous carbon. When the organometallic compound is used as a reactant instead, such as magnesocene and allyltriphenyltin, carbon encapsulated MgO and SnS nanocrystals with core-shell structure are synthesized, respectively. A detonation introduced by the violent reaction occurs in the process with a very rapid liberation of heat and large quantities of thermally expanding gases. The large amounts of free atomic/radical species and reactive intermediates are generated as sources for the core-shell structure. It is a common strategy for the large scale production of carbon encapsulated oxide/sulfide nanocrystals by means of the moderate detonation process of the organometallic compound and APS in an autoclave.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Onion-like carbon as dopant/modification-free electrocatalyst for
           [VO]2+/[VO2]+ redox reaction: Performance-control mechanism
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Young-Jin Ko, Keunsu Choi, Jun-Yong Kim, Inho Kim, Doo Seok Jeong, Heon-Jin Choi, Hiroshi Mizuseki, Wook-Seong Lee
      We investigate the application of the onion-like carbon (OLC) as an electrocatalyst for [VO]2+/[VO2]+ redox flow reaction; its performance (electrocatalytic activity and reversibility) strongly increases with the synthesis to peak at 1800 °C in 1000–2000 °C range. The dopant/modification-free, optimized redox performances of the OLC is comparable to some of the best data in the literature of various types of carbon materials with post-synthesis modifications or doping. Mechanism behind such performance optimization is investigated employing various physical/electrochemical analyses as well as the first-principles calculations. We demonstrate that the carbon dangling bonds or the crystalline defects, generated by an inherent mechanism unique to the OLC, played a pivotal role in determining the electrocatalytic performances.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Transfer-free growth of polymer-derived graphene on dielectric substrate
           from mobile hot-wire-assisted dual heating system
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Jinwook Baek, Myeongsoo Lee, Jungmo Kim, Jinsup Lee, Seokwoo Jeon
      Chemical vapor deposition (CVD) is the most promising, relatively inexpensive approach for the growth of high quality graphene. However, the need to transfer the graphene to dielectric substrates limits its usage in electronic applications. Here, we demonstrate transfer-free growth of graphene on dielectric substrates via mobile hot-wire (MHW) assisted dual heating system (DHS). MHW is utilized as independent heat source over polymer/Ni/SiO2/Si, which is placed on a bottom heater. The hot-wire scan speed (Vw, 0.01–40 mm/min) and temperature (Tw) are varied to control the diffusion kinetics and amount of carbon source into nickel by changing the cooling rate of hot zone where nucleation and growth of graphene occurs between Ni and SiO2. The optimum growth condition for single-layer graphene is further verified through controlling the substrate temperature (Tsub, 430–630 °C). We also improve coverage of graphene by changing polymers as a function of thermal stability. The results show that thermal decomposition temperature determines the amount of the carbon dissolved into nickel for graphene growth. Through our synthesis, we can obtain nearly full-coverage of single-layer graphene. We believe our simple method of growing graphene is potentially scalable and advances the possibility of various electrical and optical applications.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Spectroscopic investigations on the origin of the improved performance of
           composites of nanoparticles/graphene sheets as anodes for lithium ion
           batteries
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Xiu-Mei Lin, Thomas Diemant, Xiaoke Mu, Ping Gao, R.Jürgen Behm, Maximilian Fichtner
      Composites of nanoparticles/graphene sheets show an improved lithium storage capacity and cycling stability compared to bare graphene sheets (GSs). They are therefore considered as one of the promising candidates of anode materials for portable electrochemical energy storage devices requiring lightweight and ultrathin batteries. The practical application of these materials relies on the in-depth understanding of the origin of their improved performance. In this work, a composite of silver nanoparticles and graphene sheets (Ag/GSs) has been used as a model material to investigate the origin of the improved electrochemical performance by impedance, ex situ XPS and in situ Raman spectroscopy. We found that the Ag/GSs composite electrode has higher electrical conductivity than GSs. AgLix alloy was formed during the lithiation. Insertion of Ag nanoparticles into the interlayers between graphene sheets reduced the mean number of graphene stacking layers in the composite and provided a better site accessibility for Li+ insertion. Comparative in situ Raman measurements of them showed a completely reversible structural evolution of graphene sheets in Ag/GSs during the first lithiation/de-lithiation process, while for GSs the structural stability was worse. In combination, these effects are favorable for improving the reversible capacity and retaining the cycle stability of the Ag/GSs composite.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Room-temperature ferromagnetism from an array of asymmetric zigzag-edge
           nanoribbons in a graphene junction
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Hosik Lee, Hyun-Jung Lee, Sung Youb Kim
      Room-temperature ferromagnetism in graphene layers with defects has been experimentally measured. Despite disagreement around the intrinsic origin of carbon magnetism, experimental evidence has supported the existence of paramagnetism or ferromagnetism in carbon materials. Convincing theoretical explanations, however, have not yet been proposed. In this work, density functional theory calculations were used to suggest a plausible explanation for this phenomenon as it is observed at the zigzag grain boundaries of a mismatched single-double-single-layer graphene junction. We identified asymmetric zigzag-edge graphene nanoribbons that display ferromagnetic properties in a graphene junction structure. Two ferromagnetic asymmetric zigzag graphene nanoribbons displayed antiferromagnetic coupling in a defect-free structure at the grain boundary. The introduction of a vacancy or N-substitutional defect was found to destroy the magnetism on one side only; the nanoribbon on the other side continued to display a large ferromagnetic exchange coupling. The ferromagnetic nanoribbon in the junction was ferromagnetically correlated with other nanoribbons in the two-dimensional junction array, yielding a Curie temperature well-above room temperature. Moreover, the ferromagnetic correlation was observed regardless of the arrangement of the magnetic layers, enabling ferromagnetic ordering within the graphene junction array.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Lattice thermal conductivity of graphene nanostructures
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): M. Saiz-Bretín, A.V. Malyshev, F. Domínguez-Adame, D. Quigley, R.A. Römer
      Non-equilibrium molecular dynamics is used to investigate the heat current due to the atomic lattice vibrations in graphene nanoribbons and nanorings under a thermal gradient. We consider a wide range of temperature, nanoribbon widths up to 6 nm and the effect of moderate edge disorder. We find that narrow graphene nanorings can efficiently suppress the lattice thermal conductivity at low temperatures ( ∼ 100 K ), as compared to nanoribbons of the same width. Remarkably, rough edges do not appear to have a large impact on lattice energy transport through graphene nanorings while nanoribbons seem more affected by imperfections. Furthermore, we demonstrate that the effects of hydrogen-saturated edges can be neglected in these graphene nanostructures.
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      PubDate: 2017-11-09T07:22:54Z
       
  • Fully-transparent graphene charge-trap memory device with large memory
           window and long-term retention
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Sejoon Lee, Youngmin Lee, Sung Min Kim, Emil B. Song
      A fully-transparent graphene-based charge-trap memory device was realized by fabricating a graphene-channel field-effect transistor with high-k/low-k/high-k oxide stacks of Al2O3/AlOx/Al2O3 and indium-tin-oxide gate/source/drain electrodes on the polyethylene naphthalate substrate (i.e., ITO-gated AXA-gFET). The usage of low-k AlOx as a charge-trap layer allowed us to demonstrate a high-performance memory device, exhibiting a large memory window of ∼9.2 V and a tenacious retention of the memory window margin up to ∼57% after 10 years. Memory cells comprising the ITO-gated AXA-gFET arrays displayed a high transparency with the average optical transmittance of ∼83% in visible wavelength regions. These properties may move us a step closer to the practical application of graphene-based memories for future transparent electronics. In-depth analyses on the electrical characteristics and the mechanisms of the memory functions are presented.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Hierarchical-graphene-coupled polyaniline aerogels for electrochemical
           energy storage
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Yang Qu, Chenbao Lu, Yuezeng Su, Daxiang Cui, Yafei He, Chao Zhang, Ming Cai, Fan Zhang, Xinliang Feng, Xiaodong Zhuang
      Graphene oxide (GO) is one of the most popular materials for preparing aerogels as monolith electrodes for supercapacitors because of its promising mechanical property and relatively good conductivity after thermal reduction. However, low surface area and restacking of reduced graphene nanosheets still limit the performance of the supercapacitors based on GO-derived aerogels. In this work, graphene-coupled polyaniline (PANI) nanosheets (GO@PANI), which were synthesized through interfacial polymerization method, were used to co-assemble with GO towards hierarchical-graphene-coupled PANI aerogels by hydrothermal strategy. The resultant new hybrid aerogels exhibited a typical three-dimensional (3D) porous structure with rich graphene/PANI heterostructure and high specific surface area of up to 337 m2/g. As electrodes for symmetric and asymmetric all-solid-state supercapacitors, the aerogels delivered areal capacitances of up to 453 and 679 mF/cm2, respectively, which are superior to those of most GO- and/or PANI-derived aerogel-based supercapacitors. This excellent electrochemical performance can be attributed to the synergistic contribution of the local conductivity of graphene layers sandwiched between PANI layers and long-distance conductivity of 3D graphene frameworks. The developed hierarchical-assembly method can be widely used for fabricating two-dimensional sandwich-type material-based aerogels with versatile applications.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • One-pot synthesis of nitrogen-doped ordered mesoporous carbon spheres for
           high-rate and long-cycle life supercapacitors
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Jian-Gan Wang, Hongzhen Liu, Huanhuan Sun, Wei Hua, Huwei Wang, Xingrui Liu, Bingqing Wei
      Nitrogen-doped ordered mesoporous carbon spheres (N-OMCS) were prepared by a facile one-pot soft-templating and one-step pyrolysis method. The as-obtained N-OMCS possesses an average diameter of around 300 nm, a moderate specific surface area of 439 m2 g−1 and uniform mesopore size at around 5.0 nm. Owing to the ordered meso-structure and nitrogen doping, the N-OMCS materials, when used as supercapacitor electrodes, delivers a high specific capacitance of 288 F g−1 at a current density of 0.1 A g−1. More remarkably, the N-OMCS electrode shows excellent rate capability with 66% capacitance retention at an ultrahigh current density of 50 A g−1 and outstanding cycling stability with almost no degradation over 25,000 cycles. The work would open up a new avenue to synthesize carbon spheres with mesoporous structure and nitrogen doping for high-performance supercapacitor applications.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Size-dependent cell uptake of carbon nanotubes by macrophages: A
           comparative and quantitative study
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Minfang Zhang, Mei Yang, Takahiro Morimoto, Naoko Tajima, Kayo Ichiraku, Katsuhide Fujita, Sumio Iijima, Masako Yudasaka, Toshiya Okazaki
      Quantification of the cellular uptake of nanomaterials is crucial for studies of their toxicity and medical applications. However, our knowledge of the behaviors of carbon nanotubes (CNTs) in cells or tissues remains incomplete due to the lack of appropriate methods for quantitative analysis. Here, we present a unique methodology for quantitatively assessing the cellular uptake of CNTs, taking advantage of their absorption of light in the near-infrared region. Measurement of CNT concentration in cell lysates by monitoring absorbance at 750 nm enabled highly accurate quantification of CNTs accumulated within cells. In a comparative study of eight commercially available CNTs with dynamic size ranging from 30 to 400 nm, we obtained the first quantitative evidence that cellular uptake of CNTs by RAW264.7 macrophages depends on their sizes, specifically on the widths of their bundles in dispersion, regardless of type or manufacturer. Specifically, uptake of CNTs increased linearly with dynamic size, and cytotoxicity increased along with uptake.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Largely enhanced thermal conductivity of graphene/copper composites with
           highly aligned graphene network
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Ke Chu, Xiao-hu Wang, Fan Wang, Yu-biao Li, Da-jian Huang, Hong Liu, Wen-lin Ma, Feng-xia Liu, Hu Zhang
      Graphene has an ultra-high thermal conductivity (TC) along its basin plane. However, the TC of graphene/metal composites is still far below the expectation due primarily to the lack of sufficient graphene alignment in the metal matrix. Herein, we reported an efficient route to prepare the graphene nanoplatelet (GNP)/Cu composites with highly aligned GNPs by a vacuum filtration method followed by spark plasma sintering. Impressively, when the GNP fraction reached 35 vol%, a long-range and highly aligned GNP network was established within the Cu matrix, leading to a surprisingly high in-plane TC of 525 W/mK, which was 50% higher than that of Cu matrix and among the highest value ever reported for bulk graphene/metal composites. These results demonstrated that our strategy to construct a highly aligned graphene network could indeed achieve the remarkable in-plane TC enhancement in graphene/metal composites, and resulting composites may find application in electronic packaging that requires efficient directional heat transfer.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Scanning atmospheric plasma for ultrafast reduction of graphene oxide and
           fabrication of highly conductive graphene films and patterns
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Faisal Alotaibi, Tran T. Tung, Md J. Nine, Shervin Kabiri, Mahmoud Moussa, Diana N.H. Tran, Dusan Losic
      A new method based on scanning atmospheric plasma for an ultrafast reduction of graphene oxide (GO) and preparation of highly conductive graphene films and patterns is presented. This simple method is shown to provide a direct and scalable fabrication of graphene films on flexible and shaped substrates with a variety of patterns for broad applications. An effective and ultrafast (∼60 s) reduction of GO films into highly conductive graphene films at room temperature is demonstrated by this process that is impossible to achieve by conventional wet chemical and thermal reduction process. The software controlled x-y scanning unit allows fabrication of graphene films with variety of patterns on different substrates including glass, plastic, ceramics and metals with complex shapes required for flexible and wearable electronics and devices. Characterization results confirmed that a thin transparent graphene film can be produced with a surface sheets resistance of 22 kΩ/sq at the transparency of 88%, and a thick film (∼25 μm) with a sheet resistance of 186 Ω/sq. A practical application of plasma fabricated graphene films was demonstrated for a supercapacitor devices able to deliver an outstanding volumetric capacitance of 536.55 F/cm3 at a current density of 1 A/g.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Fabrication characterization and potential applications of carbon
           nanoparticles in the detection of heavy metal ions in aqueous media
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Aaron Simpson, R.R. Pandey, Charles C. Chusuei, Kartik Ghosh, Rishi Patel, Adam K. Wanekaya
      Carbon nanoparticles were prepared from glycerol by a thermal process in the presence of H3PO4. These particles were spherical with an average diameter of 66 nm and consisted of a carbon core with carboxylic acid and alcohol functional groups on the surface. The particles were characterized using Fourier-transform infrared, electron microscopy, X-ray diffraction, light scattering, ultraviolet–visible, fluorescence, and X-ray photoelectron spectroscopy techniques. Glassy carbon electrodes were modified, by drop casting, with the carbon nanoparticles and used for heavy metal detection with square wave anodic stripping voltammetry. Parameters such as accumulation (pre-concentration) time, amount of carbon nanoparticles casted, reduction time and reduction potential were optimized. Potential application of these glassy carbon electrodes modified with carbon nanoparticles for electrochemical analysis was demonstrated by the detection of heavy metal ions in tap water. The average recoveries of Pb2+ and Cu2+ in spiked tap water samples were 98.2% and 96.7% with a relative standard deviations of 7.4% and 8.5%, respectively.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Controlling hydrogen environment and cooling during CVD graphene growth on
           nickel for improved corrosion resistance
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): M.R. Anisur, P. Chakraborty Banerjee, Christopher D. Easton, R.K. Singh Raman
      Lack of uniformity and generation of defects including grain boundaries and wrinkles in graphene coatings synthesized using chemical vapour deposition (CVD) adversely affect the durability of these coatings. In order to control the defect density and to improve the durability of corrosion resistance of the resultant graphene coating, a fundamental understanding of the influence of the CVD parameters on the defect density is of utmost importance. In this study, the influences of hydrogen flow during graphene growth and the cooling rate on the defect density and barrier properties of a graphene coating have been investigated. A thorough microscopic and spectroscopic investigation revealed that (i) slow cooling hindered the formation of graphene coating irrespective of the presence or absence of hydrogen flow, and (ii) under rapid cooling condition, absence of hydrogen flow restricted wrinkle formation on the resultant coating. Diminished wrinkle formation in absence of hydrogen flow significantly improved the durability of the resultant coating. Based on an in-depth electrochemical impedance spectroscopic investigation, a mechanism has been proposed, which was further corroborated with the post-corrosion analyses using X-ray photoelectron spectroscopy and scanning electron microscopy. This study provides a new direction to achieve graphene coatings with minimal defect density and excellent barrier properties.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Direct observation of oxygen configuration on individual graphene oxide
           sheets
    • Abstract: Publication date: February 2018
      Source:Carbon, Volume 127
      Author(s): Zilong Liu, Kasper Nørgaard, Marc H. Overgaard, Marcel Ceccato, David M.A. Mackenzie, Nicolas Stenger, Susan L.S. Stipp, Tue Hassenkam
      Graphene oxide (GO) is an interesting material that has the potential for a wide range of applications. Critical for these applications are the type of oxygen bond and its spatial distribution on the individual GO sheets. This distribution is not yet well understood. Few techniques offer a resolution high enough to unambiguously identify oxygen configuration. We used a new, label free spectroscopic technique to map oxygen bonding on GO, with spatial resolution of nanometres and high chemical specificity. AFM-IR, atomic force microscopy coupled with infrared spectroscopy, overcomes conventional IR diffraction limits, producing IR spectra from specific points as well as chemical maps that are coupled to topography. We have directly observed oxygen bonding preferentially on areas where graphene is folded, in discrete domains and on edges of GO. From these observations, we propose an updated structural model for GO, with CO on its edge and plane, which confirms parts of earlier proposed models. The results have interesting implications. Determining atomic position and configuration from precise imaging offers the possibility to link nanoscale structure and composition with material function, paving the way for targeted tethering of ions, polymers and biomaterials.
      Graphical abstract image

      PubDate: 2017-11-09T07:22:54Z
       
  • Advances in carbon nanotube n-type doping: Methods, analysis and
           applications
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Liam Brownlie, Joseph Shapter
      Great advances in semiconductor technologies continue to be made with the demand for cheap, non-toxic, easily processed and environmentally friendly technologies on the rise. Single-walled carbon nanotubes (SWCNTs) are viewed as a promising candidate that satisfies these criteria however proper doping of the SWCNTs to provide n-type behaviour has been a persistent issue. In recent years, great advances have been made in providing air stable and efficient n-type doping of SWCNTs. This review presents the most recent and promising methods of n-type doping SWCNTs highlighted for their simplicity and quality of electrical properties. The analysis and major applications of these semiconductors with a focus on thermoelectric devices and transistors are discussed.
      Graphical abstract image

      PubDate: 2017-10-18T04:57:16Z
       
  • Probing the activity of pure and N-doped fullerenes towards oxygen
           reduction reaction by density functional theory
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Xin Chen, Junbo Chang, Qiang Ke
      Fullerene can be potentially used as the electrocatalyst for oxygen reduction reaction (ORR) due to its curvature and pentagon defect. In this study, the ORR mechanisms and catalytic abilities of pure and N-doped fullerenes were investigated via DFT computations. Four different sized fullerenes, C20, C40, C60, and C180, with respectively the diameter of approximately 0.4, 0.6, 0.7, and 1.2 nm, were utilized to investigate the size effect on the ORR performance. The results reveal that the smallest (C20 and N-doped one) and the largest (C180 and C179N) fullerenes are not effective ORR catalysts candidates in view of their unsuitable adsorption strength to the ORR species. In contrast, N-doped C40 and C60, with the adsorption energy much close to those on Pt(111), manifest high ORR activity potentials. Further analysis of the relative energy diagram shows that the ORR process on C19N and C179N is completed through a H2OO dissociation mechanism, while on C39N and C59N it will undergo an OOH dissociation pathway. In addition, the C39N has the largest decreased energy of rate-determining step in the relative energy profile, suggesting its ORR activity is the best among all the different sizes of fullerenes that we studied.
      Graphical abstract image

      PubDate: 2017-10-18T04:57:16Z
       
  • From blackness to invisibility – Carbon nanotubes role in the
           attenuation of and shielding from radio waves for stealth technology
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Anna Kolanowska, Dawid Janas, Artur P. Herman, Rafał G. Jędrysiak, Tomasz Giżewski, Sławomir Boncel
      Stealth technology combines numerous means and techniques to be ‘invisible’ for opponents in a battle field. Since metals are the key construction materials of military vehicles, weapon and equipment, they can be targeted and detected by RAdio Detection And Ranging (RADAR) systems. Radar-Absorbent Materials (RAMs) – as crucial components of passive countermeasures in the modern-day military tactics – are used for absorption of electromagnetic waves. In the same time, mainly due to high electric conductivity, RAMs – accompanied by designed geometry of the objects they are incorporated into – can yield programmable reflection, multiple internal reflection and scattering towards Electromagnetic Interference (EMI) shielding. Nowadays, the latest achievements of nanotechnology have transformed stealth technology into an even more powerful tool. And among many nanomaterials, carbon nanotubes (CNTs) have arisen as one of the most promising active component of RAMs and EMI shielding materials. The unique sp2-derived macromolecular architecture equips CNTs with an exceptional combination of electromagnetic, mechanical and chemical properties. This review intends to summarize and critically evaluate the hitherto efforts in the production and applications of CNT nanocomposites/hybrid materials as key constructional civil and military elements, preferably as coatings, layers, films, textiles or panels, towards attenuation of the radio wave radiation.
      Graphical abstract image

      PubDate: 2017-10-11T02:47:10Z
       
  • Ultrafast molecular transport on carbon surfaces: The diffusion of ammonia
           on graphite
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Anton Tamtögl, M. Sacchi, I. Calvo-Almazán, M. Zbiri, M.M. Koza, W.E. Ernst, P. Fouquet
      We present a combined experimental and theoretical study of the self-diffusion of ammonia on exfoliated graphite. Using neutron time-of-flight spectroscopy we are able to resolve the ultrafast diffusion process of adsorbed ammonia, NH3, on graphite. Together with van der Waals corrected density functional theory calculations we show that the diffusion of NH3 follows a hopping motion on a weakly corrugated potential energy surface with an activation energy of about 4 meV which is particularly low for this type of diffusive motion. The hopping motion includes further a significant number of long jumps and the diffusion constant of ammonia adsorbed on graphite is determined with D = 3.9 ⋅ 10 − 8 m 2 / s at 94 K.
      Graphical abstract image

      PubDate: 2017-10-11T02:47:10Z
       
  • Understanding and manipulating luminescence in carbon nanodots
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Z.C. Su, H.G. Ye, Z. Xiong, Q. Lou, Z. Zhang, F. Tang, J.Y. Tang, J.Y. Dai, C.X. Shan, S.J. Xu
      Carbon nanodots (CDs), a new star in the carbon nanomaterials family, have been demonstrated to show strong luminescence, and can meet the needs of large-scale production for biological and medical applications due to their low toxicity and biocompatibility. However, their luminescence mechanisms, such as color tuning and strong excitation-dependent luminescence, are still unclear. Herein, we present a state-of-the-art understanding and manipulating luminescence in CDs by changing their environmental states and using multiple spectroscopic methods as well as the first-principles theoretical calculations. Our study reveals that the edge-carbon atoms and incorporated nitrogen atoms play critical roles in the luminescence mechanisms of CDs, and thus paves the way for manipulation of luminescence in CDs.
      Graphical abstract image

      PubDate: 2017-10-11T02:47:10Z
       
  • Role of different nitrogen functionalities on the electrochemical
           performance of activated carbons
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Tomás Cordero-Lanzac, Juana M. Rosas, Francisco J. García-Mateos, Juan J. Ternero-Hidalgo, José Palomo, José Rodríguez-Mirasol, Tomás Cordero
      Different oxidation, reduction and thermal methods are used for selectively obtaining each of the most common surface nitrogen groups (almost isolated) on the surface of a phosphorus-containing activated carbon (ACP), and their electrochemical performances are analyzed. Nitro- and amino-containing activated carbons show defined pseudocapacitive peaks, characteristic of redox processes, which can be associated to the formation of hydroxylamino groups (observed by means of XPS). Condensed structures of nitrogen, such as pyridinic and pyrrolic, additionally improve the ionic diffusion on the carbonaceous structure, increasing the specific capacitance of the carbon electrode up to 317 F g−1. The formation of poly (amido-amine) chains on ACP surface leads to an activated carbon with poor textural properties (ABET = 43 m2 g−1) but surprisingly high surface capacitances (ca. 3256 mF m−2) attributed to an enhancement of the carbon conductivity. Some of the activated carbons are submitted to a severe thermal treatment at 900 °C, yielding carbons with a developed porous texture, stable surface phosphorus groups and an increased proportion of quaternary nitrogen surface species. These activated carbons exhibit a faster development of the electric double layer, due to the more ordered carbon planes and the presence of charged functional groups.
      Graphical abstract image

      PubDate: 2017-10-11T02:47:10Z
       
  • Electric birefringence of carbon nanotubes: Single- vs double-walled
    • Abstract: Publication date: January 2018
      Source:Carbon, Volume 126
      Author(s): Paloma Arenas-Guerrero, María L. Jiménez, Kenneth Scott, Kevin J. Donovan
      When subjected to an external electric field, carbon nanotubes in suspension are polarized and forced to rotate due to the consequent electric torque. The analysis of this electro-orientation is interesting not only at a fundamental level, but also because of the many applications that require the alignment of these particles. Moreover, the study of the interaction of the tubes with an electric field is a highly informative non-invasive technique, able to provide much information on their microscopic properties. In order to monitor the orientation of the particles, in this work we measured the macroscopic optical anisotropy of the suspension, or electric birefringence, that emerges when the tubes are oriented by the field. Two types of particle were studied: single-walled and double-walled carbon nanotubes. The electric, optical and geometrical properties of the suspended tubes were analysed via the field dependence of the electric birefringence over a wide range. Remarkably, it was found that, whilst single-walled carbon nanotubes show a positive signal, double-walled carbon nanotubes exhibit a negative birefringence caused by an anomalous optical anisotropy.
      Graphical abstract image

      PubDate: 2017-10-11T02:47:10Z
       
 
 
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