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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (50 journals)
    - CHEMISTRY (597 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (66 journals)

CHEMISTRY (597 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 7)
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: 31)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 218)
ACS Photonics     Full-text available via subscription   (Followers: 10)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
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: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 48)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 12)
Advances in Chemistry     Open Access   (Followers: 12)
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: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 18)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 10)
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: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 25)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Full-text available via subscription   (Followers: 12)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 153)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 204)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
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: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 26)
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: 3)
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: 9)
Biochemistry     Full-text available via subscription   (Followers: 278)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
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: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 109)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 99)
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: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 67)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
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: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 69)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 165)
Chemical Science     Open Access   (Followers: 21)
Chemical Technology     Open Access   (Followers: 15)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
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: 137)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 17)
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: 43)
Chemistry of Materials     Full-text available via subscription   (Followers: 189)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
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: 23)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 9)
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: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
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: 2)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 4)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 48)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
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: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 8)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)
Environmental Science : Nano     Partially Free   (Followers: 1)
Environmental Toxicology & Chemistry     Hybrid Journal   (Followers: 19)

        1 2 3 | Last

Journal Cover Carbon
  [SJR: 2.109]   [H-I: 194]   [67 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6223
   Published by Elsevier Homepage  [3031 journals]
  • Facile growth of vertically-aligned graphene nanosheets via thermal CVD:
           The experimental and theoretical investigations
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Huaping Wang, Enlai Gao, Peng Liu, Duanliang Zhou, Dechao Geng, Xudong Xue, Liping Wang, Kaili Jiang, Zhiping Xu, Gui Yu
      Owing to the distinctively morphological and structural features, vertically-aligned graphene nanosheets (VGs) possess many unique properties and hold great promise for applications in various fields. For controllable preparation and wide application of VGs, the establishing reliable growth method and profound understanding of the growth mechanism are of vital significance. Up to date, VGs are normally produced by plasma-enhanced chemical vapor deposition (PECVD) and it's considered that plasma is an indispensible factor for the vertical alignment of graphene sheets. Herein, for the first time, we report the facile and controllable VGs growth via a thermal CVD by precisely tuning growth parameters. Experimental observations in combination with detailed energy calculations reveal that the flow rate of carbon precursor determines the growth dynamics of graphene in CVD. This work offers a novel and reliable technique for VGs preparation and provides new insights into the intrinsic mechanism of vertical graphene growth. Furthermore, benefiting from the ultra-high density of edge sites, thin thickness, and outstanding electrical conductivity of VGs, the as-prepared VGs exhibit excellent field-emission performance such as ultra-low turn-on electric field and threshold field down to 1.07 and 1.65 V μm−1, respectively.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Decoupling of graphene from Ni(111) via formation of an interfacial NiO
           layer
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Yuriy Dedkov, Wolfgang Klesse, Andreas Becker, Florian Späth, Christian Papp, Elena Voloshina
      A combination of surface science techniques (STM, XPS, ARPES) and density-functional theory calculations was used to study the decoupling of graphene from Ni(111) by oxygen intercalation. The formation of an antiferromagnetic (AFM) NiO layer at the interface between graphene and the ferromagnetic (FM) Ni is found, where graphene protects the underlying AFM/FM sandwich system. It is found that graphene is fully decoupled in this system and strongly p-doped via charge transfer with a position of the Dirac point of ( 0.69 ± 0.02 ) eV above the Fermi level. Our theoretical analysis confirms all experimental findings, addressing also the interface properties between graphene and AFM NiO.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • A facile synthesis method for highly water-dispersible reduced graphene
           oxide based on covalently linked pyridinium salt
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Dong Geun Shin, Hyeonuk Yeo, Bon-Cheol Ku, Munju Goh, Nam-Ho You
      We simultaneously conducted reduction and functionalization processes on graphene oxide (GO) in order to obtain functionalized reduced GO (rGO). One of the main barriers to the development of rGO is its poor dispersibility in water and polar solvents. Nevertheless, the rGO synthesized in this study exhibits high dispersibility in water. In this research, we prepared GO by oxidizing graphite using the Hummers method, and it was functionalized by 4-pyridine moiety using 4-hydrazinylpyridine graphene (rGO-4Py). The rGO-4Py was further functionalized by methylation using methylpyridinium iodide, producing reduced graphene oxide (rGO-4Py-MeI). The resulting rGO-4Py-MeI exhibited good dispersion in water due to the effect of the pyridinium. The rGO-4Py-MeI's potential as a nanocomposite filler was evaluated by mixing it into water-soluble poly(vinyl alcohol) (PVA). The tensile strength and modulus of the resulting rGO-4Py-MeI/PVA nanocomposites were measured for different loadings of rGO-4Py-Me. The PVA nanocomposite embedded with 1 wt % of rGO-4Py-MeI showed increases of 69% (88.77 MPa) and 86% (4.36 GPa) in tensile strength and tensile modulus compared to neat PVA, respectively.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Properties and microstructure of nickel-coated graphite flakes/copper
           composites fabricated by spark plasma sintering
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Jianhao Chen, Shubin Ren, Xinbo He, Xuanhui Qu
      Copper (Cu) matrix composites reinforced with graphite flakes (GFs) were fabricated by spark plasma sintering, and electroless nickel plating was introduced to improve the interfacial bonding between GFs and Cu matrix. The microstructures and morphology of the composites were characterized by scanning electron microscopy and X-ray diffraction, and three-point bending test was performed to obtain the bending strength of the composites. The results showed obvious improvement in the bending properties and coefficient of thermal expansion (CTE) because of the introduction of Ni-P transition layer, and an ultralow negative CTE of −3.85 ppm K−1 for metal matrix composites was obtained for the first time. The volume shrinkage of GFs along c-axis direction under uniaxial compression stress as well as good interfacial bonding were considered to be the key reasons for the counterintuitive CTE of metal matrix composite with graphite inclusion. Furthermore, the obtained CTEs are in excellent agreement with the values reported by using the theoretical models. The ultralow CTE in Z direction, together with good mechanical properties make the composite fabricated in this study an appropriate candidate for electronic packaging material with two-dimensional heat dissipation function.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Thermal conductivity and annealing effect on structure of lignin-based
           microscale carbon fibers
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Jing Liu, Wangda Qu, Yangsu Xie, Bowen Zhu, Tianyu Wang, Xianglan Bai, Xinwei Wang
      This work reports on systematic investigation of the structure and thermal conductivity of lignin-based carbon fibers (CF) at the microscale. The lignin-based CF is produced by melt-spinning pyrolytic lignin derived from red oak. The 0 K-limit phonon scattering mean free path uncovers a characteristic structure size of ∼1.2 nm, which agrees well with the crystallite size by X-ray scattering (0.9 and 1.3 nm) and the cluster size by Raman spectroscopy (2.31 nm). The thermal conductivity of as-prepared CFs is determined at ∼1.83 W/m·K at room temperature. The thermal reffusivity of CFs shows little change from room temperature down to 10 K, uncovering the existence of extensive defects and grain boundaries which dominate phonon scattering. The localized thermal conductivity of CFs is increased by more than ten-fold after being annealed at ∼2800 K, to a level of 24 W/m·K. Our microscale Raman scanning from less annealed to highly annealed regions shows one-fold increase of the cluster size: from 1.83 nm to 4 nm. This directly confirms structure improvement by annealing. The inverse of the thermal conductivity is found linearly proportional to the annealing temperature in the range of 1000–2800 K.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Epitaxial electrical contact to graphene on SiC
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): T. Le Quang, L. Huder, F. Lipp Bregolin, A. Artaud, H. Okuno, N. Mollard, S. Pouget, G. Lapertot, A.G.M. Jansen, F. Lefloch, E.F.C. Driessen, C. Chapelier, V.T. Renard
      Establishing good electrical contacts to nanoscale devices is a major issue for modern technology and contacting 2D materials is no exception to the rule. One-dimensional edge-contacts to graphene were recently shown to outperform surface contacts but the method remains difficult to scale up. We report a resist-free and scalable method to fabricate few graphene layers with electrical contacts in a single growth step. This method derives from the discovery reported here of the growth of few graphene layers on a metallic carbide by thermal annealing of a carbide forming metallic film on SiC in high vacuum. We exploit the combined effect of edge-contact and partially-covalent surface epitaxy between graphene and the metallic carbide to fabricate devices in which low contact-resistance and Josephson effect are observed. Implementing this approach could significantly simplify the realization of large-scale graphene circuits.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Optical effective mass of photon in single and bilayer graphene in
           10 MHz–26.5 GHz frequency range
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Kamlesh Patel, Pawan K. Tyagi
      The present study has been carried out to experimentally determine the optical effective mass of photon in single layer graphene transferred on glass and quartz substrates, and bilayer graphene as-grown on Cu foil. Measurements have been performed in microstrip line based test fixture where first real and imaginary parts of complex relative permittivity have been obtained, then the refractive index is used to estimate the phase velocity in single and bilayer graphene, this index were found to be higher at lower frequency below 1.5 GHz. The phase velocities are found to be ∼ 1.04 × 108 ms−1 and ∼ 1.11 × 108 ms−1 in single and bilayer graphene, respectively and little high group velocities are found in range of 2–26.5 GHz. In single and bilayer graphene, the optical effective mass has been found to vary from ∼ 0.72 × 10−10 m 0 to ∼ 0.2 × 10−8 m 0 in a frequency range between 1 and 26.5 GHz. We envision that reported results can help to understand the transport behaviour of photons in as-grown graphene layer in microwave frequency range.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • The effect of filtered nanoparticles on gas filtration efficiency of
           granular activated carbons
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Changhyuk Kim, Handol Lee, Adam Juelfs, Christy L. Haynes, David Y.H. Pui
      Granular activated carbons (GACs) are widely used porous materials for removing gaseous contaminants in the air. In addition, GACs can work as pack-bed filters for removing particles. However, the filtered particles may block the pores of GACs, which are capture sites for gaseous contaminants, and reduce their gas filtration efficiency. In this study, the effect of the filtered particles on GAC gas filtration efficiency was investigated by measuring toluene penetration through GACs when nanoparticles were simultaneously introduced to the GACs. The nanoparticles were generated from toluene molecules through soft X-ray assisted gas-to-particle conversion and mixed in-situ with toluene molecules. The penetration of toluene through the GACs was determined by measuring the volume distribution of nanoparticles, which were converted from toluene molecules downstream of the GACs. By integrating the measured volume distribution of the nanoparticles, the total volume concentration of nanoparticles was calculated and plotted as a function of time. The time-resolved penetration of toluene remained the same regardless of the particle filtration by the GACs. Moreover, the GACs with different granule sizes had same time-resolved penetration of toluene. These experimental results showed that GACs can be used to remove nanoparticles and gas contaminants simultaneously without changing their gas filtration efficiency.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • A facile method to sensitively monitor chlorinated phenols based on
           Ru(bpy)32+ electrochemiluminescent system using graphene quantum dots as
           coreactants
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Bao-Ping Qi, Xiaoru Zhang, Bing-Bing Shang, Dongshan Xiang, Wanyun Qu, Shenghui Zhang
      Except the tunable photoluminescent property, graphene quantum dots (GQDs) with special structures have also exhibited other novel properties. Herein, GQDs played a novel coreactant role in Ru(bpy)3 2+/GQDs system to increase the anodic ECL signal of Ru(bpy)3 2+, which has been testified by ultraviolet, fluorescence, and electrochemiluminescence (ECL) experiments. Based on the coreactant mechanism of Ru(bpy)3 2+/GQDs system, a chlorinated phenol-related quenching ECL sensor was designed and the sensor showed a good linear relationship in the range from 0.60 to 55 μM with the detection limit of 1.4 × 10−8 M (S/N = 3). These results were not only beneficial to resolve the structure of GQDs, but also expanded the application field of GQDs.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Hollow carbon nanospheres as a versatile platform for co-delivery of siRNA
           and chemotherapeutics
    • Abstract: Publication date: September 2017
      Source:Carbon, Volume 121
      Author(s): Lingmin Zhang, Xinglong Yang, Ying Li, Wenfu Zheng, Xingyu Jiang
      The synergistic treatment with therapeutic nucleic acids and chemotherapeutics is considered to be a feasible strategy to overcome drug-resistant cancers. Herein, we constructed a novel amine dotted hollow carbon nanospheres (HCNs) to serve as a versatile platform for co-delivery of siRNA targeting multidrug resistance gene (MDR1) mRNA (siMDR1) and chemotherapeutics (Doxorubicin or Cisplatin) to fight drug-resistant cancers. The HCNs show enhanced loading capability of both siRNA and chemotherapeutics. The nanostructure down-regulates more than ∼96% of MDR1 protein expression of DOX-resistant breast cancer (MCF-7/ADR cells) and leads to ∼90% reduction of weight of MCF-7/ADR tumour on mice. Thus, the HCNs can be used as a good platform for drug delivery in cancer therapy.
      Graphical abstract image

      PubDate: 2017-05-27T03:52:52Z
       
  • Mildred S. Dresselhaus (1930 – 2017) – A Tribute from the
           Carbon Journal
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Robert H. Hurt, D.D.L. Chung, Mauricio Terrones, Katsumi Kaneko, Peter Thrower, Morinobu Endo, Hui-Ming Cheng, Michael Strano


      PubDate: 2017-05-27T03:52:52Z
       
  • Functionalization of γ-graphyne by transition metal adatoms
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Sunkyung Kim, Antonio Ruiz Puigdollers, Pablo Gamallo, Francesc Viñes, Jin Yong Lee
      Transition Metal (TM) atoms adsorption on γ-graphyne is here studied to unravel the electronic and magnetic properties tuning of this 2D carbon allotrope, with possible repercussions on molecular storage, sensing, and catalytic properties. A thorough density functional theory study, including dispersion, of the structural, energetic, diffusivity, magnetic, and doping properties for all 3d, 4d, and 5d TM adatoms adsorbed on γ-graphyne is provided. Overall, TMs strongly chemisorb on γ-graphyne acetylenic rings, except d 10 group XII TMs which physisorb. Diffusion energy barriers span the 0.5–3.5 eV and adatom height with respect the γ-graphyne sheet seems to be governed by the TM atomic radius. All TMs are found to give n-doped γ-graphyne, where charge transfer decays along d series due to the increasing electronegativity of TMs. Middle TMs infer noticeable magnetism to γ-graphyne, yet magnetism is heavily quenched for early and late TMs. The large adsorption energies close to parent TM bulk cohesive energies, the high diffusion energy barriers, and the coulombic repulsion between positively charged TM adatoms provide a good environment for TMs to disperse over the γ-graphyne.
      Graphical abstract image

      PubDate: 2017-05-16T22:37:17Z
       
  • Advanced bimodal polystyrene/multi-walled carbon nanotube nanocomposite
           foams for thermal insulation
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Pengjian Gong, Guilong Wang, Minh-Phuong Tran, Piyapong Buahom, Shuo Zhai, Guangxian Li, Chul B. Park
      We developed an advanced bimodal polystyrene (PS)/multi-walled carbon nanotube (MWCNT) nanocomposite foam with a very low thermal conductivity of 30 mW/m-K without using any insulation gas. The MWCNTs significantly decreased the radiative thermal conductivity of the foams with the high infrared (IR) absorption capability and increased the optimal expansion ratio of the foams to minimize the total thermal conductivity. The radiative blocking effect of MWCNTs was quantitatively modeled by calculating the IR absorption index of the unfoamed nanocomposites and calculating the IR extinction coefficient of the foamed nanocomposites. In addition, a theoretical model to analyze the optimal expansion ratio in synergistic bimodal nanocomposite foam was developed for the first time. The calculated values were in good agreement with the experimental data to verify the superior heat-blocking characteristics of the MWCNTs in the bimodal cellular morphology.
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      PubDate: 2017-05-11T22:35:35Z
       
  • Effect of trapped water on the frictional behavior of graphene oxide
           layers sliding in water environment
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Jihyung Lee, Murooj Atmeh, Diana Berman
      Two-dimensional materials have great potential for applications in the wide-reaching areas of sensing, drug delivery, and biomolecule nano-transportation. When considering graphene for possible applications, interactions with the surrounding environment should be always kept in mind, as they can cause wear and damage of the films and thus largely affect the overall performance of graphene-based devices. In this paper, we use Quartz Crystal Microbalance (QCM) to explore interactions of graphene oxide (GO) films with water at solid/liquid interface. We demonstrate that water trapped between GO layers during deposition from the water solution largely affects the response of the QCM in the liquid environment by unexpectedly increasing the resonant frequency of oscillations. Once the trapped water is released in the DI water environment or eliminated in case of graphene deposited from an ethanol solution, the resonant frequency decreases upon immersion as predicted from viscosity effect on the oscillations. The trapped water also increases friction against the QCM movement in the liquid environment, as indicated by 2–3 times larger mechanical resistance values. Our observations confirm the importance of GO composition and deposition procedures and propose a new method for releasing the trapped water from the structures and improving the tribological performance of the film in solid/liquid interface.
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      PubDate: 2017-05-11T22:35:35Z
       
  • Ultra-high toughness all graphene fibers derived from synergetic effect of
           interconnected graphene ribbons and graphene sheets
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Lizhi Sheng, Tong Wei, Yuan Liang, Lili Jiang, Liangti Qu, Zhuangjun Fan
      Here, we report a novel strategy for the synthesis of ultra-high toughness all graphene fibers using highly interconnected graphene ribbons (IGRs) and graphene sheets. Due to their interconnected structure and the synergistic effect of graphene ribbons and sheets, the graphene hybrid fiber shows moderate strength of 223 MPa, higher than those of previously reported graphene fibers without adding any other noncarbonous materials. More importantly, the graphene hybrid fiber exhibits an ultra-high toughness of 30 MJ m−3, much higher than those of graphene fiber (0.7 MJ m−3), previously reported graphene based fibers (<22 MJ m−3) and natural nacre (1.8 MJ m−3). The findings from the present study shed fundamental insight on the design of interconnected ribbon strategy addressing the conflict between strength and toughness in graphene materials.
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      PubDate: 2017-05-11T22:35:35Z
       
  • 2D-2D MnO2/g-C3N4 heterojunction photocatalyst: In-situ synthesis and
           enhanced CO2 reduction activity
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Min Wang, Meng Shen, Lingxia Zhang, Jianjian Tian, Xixiong Jin, Yajun Zhou, Jianlin Shi
      A novel MnO2/g-C3N4 heterojunction composite was synthesized via a simple in-situ redox reaction between KMnO4 and MnSO4·H2O adsorbed on the surface of g-C3N4 for the first time. MnO2 featuring 2D δ-phase layered structure was intimately attached onto the surface of g-C3N4 layers via CO bonding. Notably, the synthesized MnO2/g-C3N4 photocatalyst showed substantially enhanced photocatalytic activity in the reduction of CO2 than pure g-C3N4 and MnO2. The highest CO production amount of 9.6 μmol g−1 has been obtained at an optimized loading amount of MnO2 under 1 h irradiation of a 300 W Xe lamp. The incorporation of narrow band gap MnO2 on the surface of g-C3N4 enhanced its light harvesting ability. And the solid hetero-interface between MnO2 and g-C3N4 together with their well matched band structure was favorable for the separation of photo-induced carriers, consequently enhanced its photocatalytic activity. This novel 2D-2D MnO2/g-C3N4 heterostructure is expected to have great potentials in CO2 photoreduction.
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      PubDate: 2017-05-11T22:35:35Z
       
  • N-doped few-layered graphene-polyNi complex nanocomposite with excellent
           electrochromic properties
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Marta Nunes, Mariana Araújo, Revathi Bacsa, Roberta Viana Ferreira, Eva Castillejos, Phillipe Serp, A. Robert Hillman, Cristina Freire
      A new nanocomposite was obtained through the incorporation of N-doped few-layered graphene (N-FLG) into films of the electroactive polymer poly[Ni(3-Mesalen)] (poly[1]). The nanocomposite, N-FLG@poly[1], prepared by in situ electropolymerization, showed similar electrochemical responses to pristine poly[1], but with more well-defined redox peaks and higher current intensities, in compliance with larger electroactive surface coverage. N-FLG incorporation did not affect the electronic structure of poly[1], but decreased in 12% the molar extinction coefficient of the charge transfer band between metal and oxidized ligand, which is a promising advantage since this band is related to polymer degradation. The N-FLG@poly[1] showed multi-electrochromic behaviour (yellow in reduced state and green/russet in oxidized states) and revealed excellent improvement in electrochromic performance compared to original poly[1], specifically an increase of 71% in electrochemical stability (loss of 2.7% in charge after 10 000 switching cycles). Furthermore, nanocomposite formation decreased the switching time for oxidation (reduction) τ = 9 s (11 s) and improved the optical contrast (ΔT = 35.9%; increase of 38%) and colouration efficiency (η = 108.9 cm2 C−1; increase of 12%), for a representative film of coverage Γ = 296 nmol cm−2. The excellent electrochromic performance improvements are attributed to the alternative conducting pathways and to morphological modifications induced by N-FLG.
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      PubDate: 2017-05-11T22:35:35Z
       
  • Tuning the plasmon resonance and work function of laser-scribed chemically
           doped graphene
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Badawi Anis, A. Abouelsayed, W. El hotaby, Amany M. Sawy, Ahmed S.G. Khalil
      Here, we present terahertz spectroscopy study on laser scribed graphene (LSG) doped with monovalent Na+ cations (LSG/MNCs), silver nanoparticles (LSG/SNPs), and silver nanowires (LSG/SNWs), in the frequency range from 0.06 to 3 THz. The terahertz absorption peaks observed at ≈ 1.98, 2.06, 2.73, and 3.06 THz are attributed to the collective oscillations of free carriers in LSG, LSG/MNCs, LSG/SNPs, and LSG/SNWs, respectively. The plasmon peak position and Fermi energy E f of LSG doped samples are shifted to higher energy compared to undoped LSG indicating the n-doping of graphene. The σ d c and the charges concentration n show higher values in case of LSG/SNWs compared to other doped samples. This is mainly because silver nanowires create conducting paths between the neighboring graphene sheets. The charge density n of the LSG and LSG doped samples versus E f , scales as n1/4, illustrates power-law behavior which is the signature of the two-dimensional massless Dirac electrons.
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      PubDate: 2017-05-11T22:35:35Z
       
  • Carbon nanowalls: A new material for resistive switching memory devices
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 120
      Author(s): Paola Russo, Ming Xiao, Norman Y. Zhou
      In this work, we report for the first time the resistive switching behavior of a new type of device made of carbon nanowalls (CNWs) deposited on fluorine-doped tin oxide (FTO) substrate. This new device shows a forming-free bipolar resistive switching behavior, with a low operating voltage of 2 V and long retention time (5 × 10ˆ4 s). The CNWs are synthesized by electrophoretic deposition of a solution of polyynes obtained by arc discharge. We show that the environmentally-friendly and time-saving fabrication process we developed could overcome the current complex fabrication process of carbon-based memory devices which impede their large-scale development. The obtained results demonstrate the good reproducibility of the device's production process, and that the device's electrical performances can be engineered with a control of the fabrication parameters. The study presented suggests that CNWs are promising candidates for non-volatile memory devices and in carbon-based electronics.
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      PubDate: 2017-05-11T22:35:35Z
       
  • Hillock formation on nanocrystalline diamond
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Felipe J. Valencia, Rafael I. González, Eduardo M. Bringa, Miguel Kiwi
      Hillock formation on nanocrystalline (nc) diamond under swift heavy ion irradiation is studied by means of classical molecular dynamics. The irradiation is simulated by means of a thermal spike model, the nc samples include as many as 5 millions atoms. Our results show that hillocks on nc diamond can be created for stopping powers (SP e ) in the range of 12–17 keV/nm, and grain sizes less than 13 nm. For smaller values of the SP e only point defects are observed on the nc surface, while for larger SP e hillocks suffer a transition to crater-rim, because of the increased sputtering that is due to the large energy that the ions deposit. We observe that the sputtering yields depend quadratically on the stopping power, contrary to what has been obtained by simulations for some single crystal solids. In addition, our results show that hillocks are smaller for 5 and 7 nm grain sizes, due to the large free volume that is available on the grain boundaries. Instead, for 10 and 13 nm the hillock is limited only to the amorphization of the grain closest to the surface. No hillock formation is expected for larger grain sizes, because of the transition of the nc to pristine diamond, where no hillock formation has been observed.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Sandwich-like octahedral cobalt disulfide/reduced graphene oxide as an
           efficient Pt-free electrocatalyst for high-performance dye-sensitized
           solar cells
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Hong Yuan, Jia Liu, Qingze Jiao, Yongjian Li, Xiufeng Liu, Daxin Shi, Qin Wu, Yun Zhao, Hansheng Li
      A novel sandwich-like hierarchical structure composed of reduced graphene oxide (RGO) and uniform cobalt disulfide (CoS2) octahedrons is successfully prepared by a simple one-step solvothermal process, in which Co2+ cations attracted into graphene framework by the electrostatic adsorption induce the growth of octahedral CoS2 nanoparticles between the layers of graphene. The fascinating sandwich-like structured CoS2/RGO hybrid inherits excellent electrical conductivity of graphene skeletons. Meanwhile, CoS2 octahedrons intercalated between the layers of graphene provide both rich inner active sites for the reduction of triiodide and abundant mesoporous structure for effective electrolyte diffusion. Benefit from the synergistic effects of CoS2 octahedrons and RGO, the dye-sensitized solar cell (DSSC) assembled with this CoS2/RGO counter electrode (CE) manifests excellent photoelectric conversion efficiency (7.69%), even higher than that of DSSC with conventional noble metal Pt CE (7.38%). Furthermore, CoS2/RGO composite displays outstanding electrochemical stability in I3 −/I− redox electrolyte. Overall, this design provides a new strategy for the development of alternative Pt-free counter electrode materials in a DSSC system.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Fluorescence from graphene nanoribbons of well-defined structure
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): S. Zhao, L. Rondin, G. Delport, C. Voisin, U. Beser, Y. Hu, X. Feng, K. Müllen, A. Narita, S. Campidelli, J.S. Lauret
      Graphene nanoribbons synthesized by the bottom-up approach with optical energy gaps in the visible are investigated by means of optical spectroscopy. The optical absorption and fluorescence spectra of two graphene nanoribbons with different structures are reported as well as the life-time of the excited states. The possibility of the formation of excimer states in stacks of individual graphene nanoribbons is discussed in order to interpret the broad and highly Stokes-shifted luminescence lines observed on both structures. Finally, combined atomic force microscopy and confocal fluorescence measurements have been performed on small aggregates, showing the ability of graphene nanoribbons to emit light in the solid state. These observations open interesting perspectives for the use of graphene nanoribbons as near-infrared emitters.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Acoustic properties of model cellular vitreous carbon foams
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): M. Letellier, S. Ghaffari Mosanenzadeh, H. Naguib, V. Fierro, A. Celzard
      This paper deals with the relations between structural and acoustic properties of model vitreous carbon foams, i.e., presenting different porous structures in terms of bulk density, cell size and connectivity, while having the same composition and the same carbon texture. This is a major achievement with respect to former studies, in which foams had cell sizes directly correlated to their total porosity, thus preventing the independent analysis of these two parameters. The permeability k 0 and the absorption coefficients A of these new carbon foams were studied in relation to their porous structures. k 0 was controlled by cell diameter, and an absorption optimum is expected in the range 1 × 10 − 9 m ² < k 0 < 3 × 10 − 9 m ² . A also increased with porosity but to a lesser extent. Cellular foams had absorption peaks whose amplitude and selectivity varied greatly. A model considering foams as combinations of Helmholtz resonators in parallel was used to highlight that these peaks correspond to the resonance of the whole samples, notably related to the smallest windows present in the cell walls. Thus, it was found that the cell size controls the permeability and hence the sound absorption, but the resonance of the carbon framework may be tailored through the window size distribution.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Isotope effect on water adsorption on hydrophobic carbons of different
           nanoporosities
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yuji Ono, Ryusuke Futamura, Yoshiyuki Hattori, Shigenori Utsumi, Toshio Sakai, Katsumi Kaneko
      The adsorption isotherms of H2O and D2O on pitch-based activated carbon fibers (ACFs) of different pore widths from 0.6 to 1.5 nm were measured at 298 K. Briefly speaking, the D2O adsorption isotherms are close to the H2O adsorption isotherms. However, we observed an evident difference in the rising and desorption relative pressures for the H2O and D2O adsorption isotherms. The D2O adsorption rises at a higher relative pressure than the H2O adsorption. Correspondingly the D2O desorption occurs at a higher relative pressure than the H2O desorption. Detailed comparison of the H2O and D2O adsorption isotherms confirmed a reproducible difference over the whole relative pressure range. The different adsorption behavior of H2O and D2O in the hydrophobic micropores is discussed with the relevance to the difference in the hydrogen bonding of H2O and D2O.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Binder-jet powder-bed additive manufacturing (3D printing) of thick
           graphene-based electrodes
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Amir Azhari, Ehsan Marzbanrad, Dilara Yilman, Ehsan Toyserkani, Michael A. Pope
      Additive manufacturing (AM), also known as 3D printing, is emerging as a promising method for the fabrication of complex 3D structures and has the potential to replace the conventional techniques used in the manufacture of commercial devices based on advanced materials. Graphene has shown superior performance in various electronic devices such as electrochemical supercapacitors. However, it remains challenging to produce the thick, high loading graphene-based electrodes required to achieve a high practical energy density in full devices. Herein, we introduce a powder-bed AM technique for the fabrication of crack-free, mm-thick graphene-based electrodes, with high surface area that can be printed in complex shapes. While this technology has the potential to be used in many application areas including energy storage, conversion, and sensing, in this work, we demonstrate their use as high performance supercapacitors. Devices fabricated using thermally exfoliated graphene oxide powder had gravimetric and areal capacitance of ∼260 F g−1 and ∼700 mF cm−2, respectively at 5 mV s−1 in 1 M H2SO4 electrolyte. The supercapacitors retained 80% of their capacity over 1000 cycles. This technique provides a promising route for the fabrication and commercialization of thick, porous graphene-based devices.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Carbonization of periodic mesoporous phenylene- and biphenylene-silicas
           for CO2/CH4 separation
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Mirtha A.O. Lourenço, Moisés L. Pinto, João Pires, José R.B. Gomes, Paula Ferreira
      Periodic mesoporous organosilicas (PMO), with phenylene or biphenylene organic linkers, were thermally treated in flowing nitrogen atmosphere upon different conditions aiming the enhancement of their CO2 adsorption/separation properties. As-synthesized and template-extracted phenylene- and biphenylene-PMO were pyrolysed at 800 and 1200 °C. The effects of: i) the type of organic bridge; ii) the presence of nitrogen atoms; iii) the use of an acid catalyst prior to carbonization; and iv) pore size were investigated. It was found that pyrolysis promotes modifications in the physical-chemical and the textural properties of the PMO materials, being the formation of micropores one of the most notable differences. Furthermore, with the exception of biphenylene-PMO, the molecular-scale periodicity of the materials was strongly affected by the pyrolysis treatment probably as a result of SiC bond cleavage. The CO2 adsorption capacity and the selectivity for CO2/CH4 separation of all pyrolysed materials were enhanced. In general, the increase of the microporosity in the pyrolysed PMO is accompanied by an improvement of the CO2 adsorption properties with concomitant reduction of the CH4 adsorption behavior. The most interesting material for CO2/CH4 separation is the biphenylene-PMO pyrolysed at 1200 °C, with a selectivity of 9.5 at 25 °C and 500 kPa.
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      PubDate: 2017-05-01T08:31:25Z
       
  • On the influence of junction structures on the mechanical and thermal
           properties of carbon honeycombs
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Xiaokun Gu, Zhenqian Pang, Yujie Wei, Ronggui Yang
      Carbon honeycomb is a 3-dimensional carbon allotrope experimentally discovered recently, but its lattice structure has not been well identified. In this paper, we perform density-functional theory (DFT) calculations to examine the stability of carbon honeycombs with different configurations (chirality and sidewall width). We find that graphene nanoribbons with both zigzag edges and armchair edges can form stable carbon honeycombs if sp3 carbon-carbon bonding is formed in the junction. We further study the mechanical properties and the thermal conductivity of carbon honeycombs with different chirality and the sidewall widths using both DFT calculations and molecular dynamics simulations. All these stable carbon honeycombs exhibit superior mechanical properties (large strength and ductility) and high thermal conductivity (larger than 100 W/m K) with a density as low as 0.5 g/cm3. Light-weight carbon honeycombs could be promising functional materials for many engineering applications.
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      PubDate: 2017-05-01T08:31:25Z
       
  • Carbon nanomaterials in tribology
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Wenzheng Zhai, Narasimalu Srikanth, Ling Bing Kong, Kun Zhou
      Over the past two decades, carbon nanomaterials have attracted great interest for their confirmed friction and wear performances as well as important tribological applications. This article gives a comprehensive review of the recent developments of four typical carbon nanomaterials including fullerenes, carbon nanotubes (CNTs), graphene and nanodiamonds in tribology. Firstly, the applications of the four types of carbon nanomaterials in coatings for anti-wear enhancement and friction reduction are discussed. Secondly, the improvement of tribological behaviors for bulk materials by using CNTs, graphene and nanodiamonds as additives is reviewed. Thirdly, the discussion is conducted on the mechanisms of the fullerenes, CNTs, graphene and nanodiamonds acting as additives in lubricants to achieve friction and wear reduction. Fourthly, the progress on superlubricity using CNTs and graphene is highlighted. Finally, this review concludes with an outlook of the future studies on carbon nanomaterials in tribology, their key challenges for commercial applications, and possible solutions.
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      PubDate: 2017-04-24T14:56:14Z
       
  • Chemical reduction of graphene oxide using green reductants
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): K.K.H. De Silva, H.-H. Huang, R.K. Joshi, M. Yoshimura
      Graphene has exceptional physical, chemical, mechanical, thermal and optical properties which offer huge potential for applications in various sectors. Chemical oxidation of graphite to graphene oxide followed by the reduction process is the commonly used method for mass scale production of graphene or reduced graphene oxide (RGO). Among the large number of chemical reducing agents used to prepare RGO or graphene, the most efficient reductant is hydrazine. It is toxic in nature and harmful to the environment, thus it is in high demand to use green reductants for RGO synthesis. We understand that due to high demand of graphene/graphene oxide/reduced graphene oxide recently and which is expected to be more in future, green synthesis methods are extremely important. In this article, we have studied the synthesis methods, characterization and the possible mechanism for green reduction, especially by ascorbic acid. This article could possibly motivate the researcher worldwide to innovate new green methods for mass scale production of graphene based materials.
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      PubDate: 2017-04-24T14:56:14Z
       
  • Surface area of carbon-based nanoparticles prevails on dispersion for
           growth inhibition in amphibians
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): L. Lagier, F. Mouchet, C. Laplanche, A. Mottier, S. Cadarsi, L. Evariste, C. Sarrieu, P. Lonchambon, E. Pinelli, E. Flahaut, L. Gauthier
      The attractive properties of carbon-based nanoparticles such as graphene and its derivatives or carbon nanotubes lead to their use in many application fields, whether they are raw or functionalized, such as oxidized. These particles may finally contaminate the aquatic compartment, which is a major receptacle of pollutants. The study of their impact on aquatic organisms is thus essential. At the nano scale, recent studies have highlighted that specific surface area should be used as the most relevant descriptor of toxicity instead of the conventional mass concentration. By using a dose-response model, this work compares the chronic toxicity observed on Xenopus laevis larvae after 12-day in vivo exposure to raw, oxidized carbon allotropes, or in the presence of chemical dispersant. We show that chemical dispersion does not influence the observed chronic toxicity, whether it is through surface chemistry (oxidation state) or through the addition of a dispersant. The biological hypothesis leading to growth inhibition are discussed. Finally, these results confirm that surface area is the more suited metric unit describing growth inhibition.
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      PubDate: 2017-04-24T14:56:14Z
       
  • Preparation of porous graphene oxide by chemically intercalating a rigid
           molecule for enhanced removal of typical pharmaceuticals
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Danna Shan, Shubo Deng, Jin Li, Hubian Wang, Conghui He, Giovanni Cagnetta, Bin Wang, Yujue Wang, Jun Huang, Gang Yu
      Porous graphene oxide (GO) adsorbents were successfully prepared by connecting GO sheets with tetrafluoroterephthalonitrile (TFT) or decafluorobiphenyl (DFB) through a nucleophilic aromatic substitution reaction. Textural characterization indicated that the enlarged surface area and pore size of the as-synthesized GO-based adsorbents were favorable for the diffusion and adsorption of the typical pharmaceuticals. The GO reacted with 20 mmol/L DFB (GO-DFB20) exhibited the highest removal for six pharmaceuticals among the prepared adsorbents, and can be separated easily. The adsorption capacities of GO-DFB20 for carbamazepine (CBZ), sulfamethoxazole (SMZ), sulfadiazine (SDZ), ibuprofen (IBP), paracetamol (PCT) and phenacetin (PNT) were 340.5, 428.3, 214.7, 224.3, 350.6 and 316.1 μmol/g, respectively. The adsorption kinetics of PCT on the GO-DFB20 was faster than SMZ. According to the Langmuir fitting, the maximum adsorption capacities of GO-DFB20 for SMZ and PCT were 749.6 and 663.9 μmol/g, respectively. The spent GO-DFB20 was successfully regenerated by methanol with little loss of adsorption capacity in five successive adsorption cycles. This study shows that the porous GO adsorbent has a promising application for the removal of typical pharmaceuticals from water or wastewater.
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      PubDate: 2017-04-24T14:56:14Z
       
  • Fabrication of reduced graphene oxide micro patterns by vacuum-ultraviolet
           irradiation: From chemical and structural evolution to improving
           patterning precision by light collimation
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yudi Tu, Hiroshi Nakamoto, Takashi Ichii, Toru Utsunomiya, Om Prakash Khatri, Hiroyuki Sugimura
      Time evolution of the chemical and structural properties of vacuum-ultraviolet (VUV) reduced graphene oxide (rGO) were studied by X-ray photoelectron spectroscopy and Kelvin-probe force microscopy to reveal the mechanism of VUV photoreduction, which can be ascribed to the local photochemical process on oxygen-containing functional groups. The difference in the efficiency between VUV and ultraviolet was demonstrated and the mechanism was discussed. The lateral electrical conductivity of VUV-produced rGO bilayer was measured by conductive atomic force microscopy, which was found to be higher than rGO monolayer due to the formation of new conductive paths between layers. The precision and resolution of VUV photo-reductive patterning was improved by collimating the VUV light. This new approach succeeded in fabricating highly-resolved 1 μm wide conductive rGO patterns on SiO2/Si substrate.
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      PubDate: 2017-04-24T14:56:14Z
       
  • MoS2 nanosheets vertically grown on reduced graphene oxide via oxygen
           bonds with carbon coating as ultrafast sodium ion batteries anodes
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yongqiang Teng, Hailei Zhao, Zijia Zhang, Lina Zhao, Yang Zhang, Zhaolin Li, Qing Xia, Zhihong Du, Konrad Świerczek
      Rational material design is a key to develop high performance electrode for sodium ion batteries (SIBs). Sandwich-like graphene@MoS2@C sheets (G@MS@C), with MoS2 nanosheets perpendicularly connecting with reduced graphene oxide (rGO) through the direct chemical coupling (COMo bonds), are synthesized by a facile two-step method, which involves in situ growth of MoS2 on rGO sheets and a followed amorphous carbon coverage process. The interfacial interaction via the COMo bonds can accelerate electron transport rate and enhance structural stability of G@MS@C electrode. Meanwhile, the vertical nanostructure provides more active sites and short diffusion distance for sodium ion reaction, leading to fast electrode reaction kinetics. The rGO sheets and carbon shells not only improve the electrical conductivity of the composite, but also act as buffers to accommodate the volume changes of MoS2 and ensure the integrity of the electrode during cycling. As an anode material for SIBs, the G@MS@C electrode shows superior reversible capacity (520 mAh g−1 after 110 cycles at 100 mA g−1), excellent rate capability (304 mAh g−1 after 200 cycles at 5 A g−1) and stable cycling performance (260 mAh g−1 after 300 cycles at 10 A g−1).
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      PubDate: 2017-04-24T14:56:14Z
       
  • Preparation and electrochemical performances of graphene/polypyrrole
           nanocomposite with anthraquinone-graphene oxide as active oxidant
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yongqin Han, Tianqi Wang, Tingxi Li, Xiaoxiao Gao, Wei Li, Zonglin Zhang, Yanmin Wang, Xiaogang Zhang
      A simple and facile method for graphene/polypyrrole nanocomposite (GPy) was developed using sodium anthraquinone-2-sulfonate monohydrate (AQS) and anthraquinone-2,6-disulfonic acid disodium salt (AQDS) as both the “oxidizing active agents” as well as “redox modifier”. The AQ(D)S modified graphene oxide(GO) played the role of “active oxidant” to in situ polymerize pyrrole and convert itself to AQ(D)S modified graphene synchronously at 70 °C. The analysis of Fourier transform infrared spectroscopy (FTIR), Raman, X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) all confirmed the successful polymerization of polypyrrole and the elimination of the oxygen functional groups from GO. The bipolarons present in AQ(D)S-GPy and the high doping level proved by FTIR, Raman, electron spin resonance (ESR) and N1s of XPS analysis endowed the nanocomposite improved electrochemical performances. Specifically, AQ(D)S-GPy provided both higher specific capacitances (237 and 300 F/g) and better cycle stability than that of GPy, PPy or AQDS-Graphene. Moreover, working potential windows were enlarged to 1.5 V and 1.7 V due to the redox activity of the AQ(D)S. The symmetric supercapacitor based on AQDS-GPy exhibited high energy density (31.2 Wh kg−1 at a power density of 1.12 kW kg−1) and good cycling stability (86% capacitance retention after 2000 cycles).
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      PubDate: 2017-04-24T14:56:14Z
       
  • Lithium-metal deposition/dissolution within internal space of CNT 3D
           matrix results in prolonged cycle of lithium-metal negative electrode
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Shoichi Matsuda, Yoshimi Kubo, Kohei Uosaki, Shuji Nakanishi
      Commercialization of rechargeable Lithium (Li)-metal batteries has not been realized so far due to safety concerns and the low cycle performance. The use of a substrate with an interconnected 3D matrix is known to be an effective approach to prolong the cycle life of a Li-metal negative electrode, since the accumulation of Li deposits in the matrix can minimize the possibility of undesired dendritic growth of Li-metal. Herein, we demonstrate that a carbon nanotube (CNT)-based 3D matrix is a promising substrate material for the use of Li-metal negative electrodes. SEM and XPS analyses show that the reversible Li-metal deposition/dissolution takes place within the internal space of the CNT matrix rather than at the surface. The large electrochemical surface area and the high electrical conductivity of the matrix reduce the internal cell resistance and suppress the increases in voltage hysteresis, resulting in repetitive Li-metal deposition/dissolution.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Templated diamond growth on porous carbon foam decorated with polyvinyl
           alcohol-nanodiamond composite
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): M. Varga, S. Stehlik, O. Kaman, T. Izak, M. Domonkos, D.S. Lee, A. Kromka
      Porous and self-standing structures are highly promising as membranes, electrodes, high sensitivity gas sensors, and supercapacitors due to their high surface area and tuneable surface properties. Composition of such materials with a polycrystalline diamond film may provide new functionalities for biological and electrochemical applications. However, the diamond growth on foreign substrates as a pinhole-free continuous thin film is still a not a trivial task. Here, we present a successful templated deposition process of polycrystalline diamond film on reticulated vitreous carbon foam (C-foam). Samples of polyvinyl alcohol (PVA) polymer-nanodiamond (ND) mixtures with various ND concentrations were prepared and characterized by means of optical spectroscopy, Raman spectroscopy, dynamic light scattering, zeta potential and pH measurements. The ND/PVA mixtures are employed for the preparation of diamond film by microwave plasma enhanced chemical vapour deposition process, and the effect of their composition (NDs/PVA ratio) on the nucleation (seed density, clustering) and diamond growth (substrate etching, polymer transformation) is analysed. The nucleation, early-stage of diamond growth and the resulting diamond-coated C-foams are characterized by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The obtained results underline the importance to tailor the NDs/PVA ratio for a well-defined three-dimensional C-foam coverage with the continuous diamond film.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Dual use of carbon nanotube selective coatings in evacuated tube solar
           collectors
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Patricia M. Martinez, Vladimir A. Pozdin, Alexios Papadimitratos, William Holmes, Fatemeh Hassanipour, Anvar A. Zakhidov
      Continuous carbon nanotube sheets spun from the side of vertically aligned forests were investigated as solar selective coatings in evacuated tube collectors for solar thermal applications and for Joule heating in the absence of solar radiation. Forests grown by chemical vapor deposition at various synthesis temperatures produced sheets with tunable thermal and optical properties. The sheets were laminated on miniature and regular size evacuated tube collectors and tested at 100 mW/cm2 AM 1.5 solar illumination under high vacuum. It was found that 10 layers of carbon nanotube sheets with medium sheet areal density produced the best solar selective coating. Interestingly, carbon nanotube sheet densification with organic solvents slightly increased the reflectance and significantly decreased the emissivity; improving the thermal transport even further. By taking advantage of the Joule heating effect, carbon nanotube sheets provide fast and efficient heating rates on demand, which can be useful in solar water heating systems when solar radiation is insufficient. Compared with commercial coatings, carbon nanotube sheets were found to have higher absorption and lower reflection in the visible and near UV region of the solar spectrum, making them ideal solar selective coatings for evacuated tube collectors even in overcast weather.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Chemically interconnected light-weight 3D-carbon nanotube solid network
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Sehmus Ozden, Thierry Tsafack, Peter S. Owuor, Yilun Li, Almaz S. Jalilov, Robert Vajtai, Chandra S. Tiwary, Jun Lou, James M. Tour, Aditya D. Mohite, Pulickel M. Ajayan
      Owing to the weak physical interactions such as van der Waals and π-π interactions, which hold nanotubes together in carbon nanotube (CNT) bulk structures, the tubes can easily slide on each other. Creating covalent interconnection between individual carbon nanotube (CNT) structures could remarkably improve the properties of their three-dimensional (3D) bulk structures. The creation of such nanoengineered 3D solid structures with improved properties and low-density remains one of the fundamental challenges in real-world applications. Here, we report the scalable synthesis of low-density 3D macroscopic structure made of covalently interconnected nanotubes using free-radical polymerization method after functionalized CNTs with allylamine monomers. The resulted interconnected highly porous solid structure exhibits higher mechanical properties, larger surface area and greater porosity than non-crosslinked nanotube structures. To gain further insights into the deformation mechanisms of nanotubes, fully atomistic reactive molecular dynamics simulations are used. Here we demonstrate one such utility in CO2 uptake, whose interconnected solid structure performed better than non-interconnected structures.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Structure and electron field emission properties of ion beam reduced
           graphene oxide sheets
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): G. Jayalakshmi, K. Saravanan, T. Arun, K. Suresh, B. Sundaravel, B.K. Panigrahi, D. Kanjilal
      We report the structure and electron field emission properties of ion beam reduced graphene oxide (GO). 500 keV Ar+ ion beam was used to reduce the GO, synthesized by modified Hummer’s method. X-ray photoelectron spectroscopy and Resonant Rutherford backscattering spectrometric analyses evidenced that the oxygen functional groups drastically reduced upon irradiation. Further, the ion beam reduced GO exhibits enhanced electron field emission property. The exponential reduction of oxygen concentration is correlated with the field enhancement factor. Raman studies shows that ion irradiation process does not introduced any additional defects in GO. Scanning electron microscopic analysis reveals layered structure of GO sheets upon ion irradiation. Our investigation demonstrated that ion beam irradiation of GO yields a highly enhanced field emission with low turn-on voltage without deteriorating its structure.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Optically transparent composite diamond/Ti electrodes
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Petr Ashcheulov, Andrew Taylor, Joris More-Chevalier, Alexander Kovalenko, Zdeněk Remeš, Jan Drahokoupil, Pavel Hubík, Ladislav Fekete, Ladislav Klimša, Jaromír Kopeček, Jarmila Remiášová, Michal Kohout, Otakar Frank, Ladislav Kavan, Vincent Mortet
      It is important for electro-optical applications of nanocrystalline diamond (NCD) films to achieve high optical transparency with low electrical resistivity. However, currently fabrication of highly transparent NCD films with reasonable electrical conductivity remains a challenge – any increase in conductivity simultaneously reduces transparency. Here, we report on fabrication of highly conductive and yet highly transparent electrodes based on boron-doped nanocrystalline diamond (B-NCD) films and Ti grids. We studied B-NCD films with variable boron content and thickness to determine preferable electrical and optical characteristics. Composite electrodes with a sheet resistance of 200 Ω/sq and optical transparency of 80% have been obtained by the integration of a thin nanostructured Ti-grid, sandwiched between the glass substrate and B-NCD layer.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Pyrolysis-induced synthesis of iron and nitrogen-containing carbon
           nanolayers modified graphdiyne nanostructure as a promising core-shell
           electrocatalyst for oxygen reduction reaction
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yanrong Li, Chaozhong Guo, Jiaqiang Li, Wenli Liao, Zhongbin Li, Jin Zhang, Changguo Chen
      Low-cost facile fabrication of highly efficient non-precious-metal catalysts to replace commercial Pt-based catalysts for oxygen reduction reaction (ORR) has attracted great attentions, because it is significant for rapid commercialization of fuel cells. Based on a fact that graphdiyne, another member of the carbon family, has not been systematically investigated as a new carbon support to ORR catalysts. We here report an effective strategy for easy synthesis of a cheap iron-nitrogen-doped carbon nanolayers wrapped around graphdiyne core-shell electrocatalyst (Fe-PANI@GD-900) for ORR from one-step pyrolysis of iron and polyaniline loaded onto graphdiyne nanocomposite at 900 °C. Electrochemical results indicate that the catalyst exhibits unexpectedly high ORR activity with onset and half-wave potentials of 1.05 V and 0.82 V (vs. RHE), while its mass activity at given potentials is lower than that of the Pt/C catalyst. Moreover, Fe-PANI@GD-900 follows a direct four-electron reduction pathway, and its long-term stability is superior to Pt/C and other graphdiyne-based catalysts previously reported in the literature. The relatively excellent ORR performance may be largely attributed to the formation of high contents of graphitic-N and FeN compounds, and the addition of graphdiyne facilitating to absolutely accelerate ORR charge transfer and fully expose more N-doped active sites on the surface.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Electrophoretic assembly and topological weaving of crumpled
           two-dimensional sheets with entangled defect loops
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): K. Rohana Wijewardhana, Tian-Zi Shen, M.R. Vengatesan, Joosung Kim, Hyoyoung Lee, Jang-Kun Song
      Transport, relocation, and self-assembly of nano and microparticles in colloidal systems are highly demanded in nanotechnology, photonics, microfluidics, and biotechnology; topological charges can provide an effective means for these purposes. We report that crumpled two-dimensional (2D) graphene oxide (GO) particle sheets in nematic fields can serve as a nest for complicated topological defect loops, which, in turn, provide mobility and inter-adhesiveness to the GO particles. The application of electric fields actuated the GO particles orthogonally, inducing their coalescence into large radial clusters upon absorption of other GO particles. In contrast, in the isotropic phase, where no topological defects existed, the GO particles electrostatically repelled each other owing to the presence of surface charges with equal sign. We also demonstrate that predesigned shallow surface trenches on a substrate can anchor seed GO particles, which attract other GO particles to create a macroscopic structure along the trench.
      Graphical abstract image

      PubDate: 2017-04-24T14:56:14Z
       
  • Structural prediction of graphitization and porosity in carbide-derived
           carbons
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Carla de Tomas, Irene Suarez-Martinez, Fernando Vallejos-Burgos, María J. López, Katsumi Kaneko, Nigel A. Marks
      Carbide-derived carbons (CDCs) are nanoporous carbons with a tunable pore size, making them desirable for their adsorption properties. Despite their applicability, reliable structural models are difficult to construct due to the interplay between strong short-range order and long-range disorder. Here, a mimetic methodology is developed to generate atomistic models of CDCs using Molecular Dynamics and the Environment Dependent Interaction Potential. This approach reproduces the main characteristics of experimentally-prepared CDCs, including microstructure, porosity at the nanometre scale, and graphitization with increasing temperature. An Arrhenius-based approach is used to bridge the timescale gap between Molecular Dynamics and experiment and build a connection between the simulation and synthesis temperatures. The method is robust, easy to implement, and enables a fast exploration of the adsorption properties of CDCs.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Flowing suspensions of carbon black with high electronic conductivity for
           flow applications: Comparison between carbons black and exhibition of
           specific aggregation of carbon particles
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): H. Parant, G. Muller, T. Le Mercier, J.M. Tarascon, P. Poulin, A. Colin
      Flow batteries and flow capacitors are promising technologies to store and generate electrical power. However, to increase their energy performances, low viscosity, electronic conductive suspensions loaded with active material are required. Comparing the behavior of three types of carbon black particles in water suspensions, we show that compressed acetylene carbon black particles suspensions display a slow variation of viscosity and conductivity as a function of concentration. It allows reaching intermediate viscosity (1 Pa s for a shear rate of 10 s−1) with high electronic conductivity between 0.1 and 5 mS/cm. This behavior is very promising for flow applications. At small range, attractive van der Walls interactions between carbon aggregates dominate. However, at longer range, compressed acetylene carbon black particles are highly attractive in water. After shearing with emulsifier, fractal-like shape clusters are obtained through a diffusion limited aggregation process. These fractal clusters constitute the building blocks of a flexible connected network. By contrast, for the two other investigated carbons, an energy barrier has to be overcome to enable aggregation. The clusters are compact and result from a reaction limited aggregation process. For these two carbons, the conductivity and the viscosity vary abruptly at percolation which is not suitable for flow devices.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Experimental and computational analysis of carbon molecular sieve membrane
           formation upon polyetherimide pyrolysis
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Janice B.S. Hamm, Andre R. Muniz, Liliane D. Pollo, Nilson R. Marcilio, Isabel C. Tessaro
      Carbon molecular sieve membranes (CM) are typically synthesized through pyrolysis of polymers, and are suitable for gas separation under high pressure conditions due to their high selectivity and mechanical strength. There is a lack of knowledge of the mechanisms of membrane formation during pyrolysis, which would be of fundamental importance to a better understanding and precise control of the process. In this work, we investigate the process of CM formation upon pyrolysis of polyetherimide. A carbon membrane was synthesized on a ceramic support and characterized by different techniques, demonstrating the conversion of the polymeric precursor into a porous and predominantly amorphous carbon structure, containing embedded graphitic domains. The membrane showed effective molecular sieve performance as demonstrated in gas permeation tests. Reactive molecular dynamics simulations were carried out to explore the mechanisms of the polymer→CM transformation at the atomistic level. The simulations show that the continuous reaction among the reactive radicals formed upon polymer pyrolysis along with atomic rearrangements spontaneously led to the formation of a nanoporous amorphous carbon matrix, containing interconnected graphitic domains throughout the structure, as observed in the experiments. These results are expected to be of great help to the development of techniques for controllable synthesis of CMs.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Unconventional mesopore carbon nanomesh prepared through
           explosion–assisted activation approach: A robust electrode material for
           ultrafast organic electrolyte supercapacitors
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Dewei Wang, Shijia Liu, Lei Jiao, Guoli Fang, Guihong Geng, Jinfu Ma
      This work presented an unconventional mesopore carbon nanomesh (MCNM), featured with numerous evenly distributed in–plane micro/mesopores, which was obtained by a novel explosion–assisted activation process employing carboxymethylcellulose sodium (CMCS) as the carbon precursor while potassium nitrate (KNO3) acts as both an explosive and activating reagent. This work opens a new route toward nanocarbon materials for high–performance electrochemical energy storage devices, which is totally different from the previously reported approaches. Considering the mesopore carbon nanomesh structures combined with the presence of abundant in–plane micro/mesopores as well as large specific surface area, the application of the MCNM materials in high–performance symmetric supercapacitors in organic electrolyte was investigated. The supercapacitor device exhibited competitive performance, including high specific capacitance (up to 149 F/g at 1 A/g), extremely high rate capability (84.6% from 1 A/g to 50 A/g), small IR drop (0.37 V at 50 A/g), outstanding cycling stability (99% capacity retention over 5000 cycles), and reasonable energy densities of 28.7 Wh/kg at an ultrahigh power density of 54000 W/kg. The facile, low–cost and scalable synthesis strategy together with excellent electrochemical performance makes it suitable for applications in electrochemical energy storage devices such as supercapacitors.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Volume control of expanded graphite based on inductively coupled plasma
           and enhanced thermal conductivity of epoxy composite by formation of the
           filler network
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Hyun Su Kim, Jong Hyeok Kim, Woo Young Kim, Hun Su Lee, Seong Yun Kim, Myung-Seob Khil
      Expanded graphite (EG) is noticed as a thermally conductive carbon filler because of its advantages of a unique structure in which graphite sheets are intercalated and relatively a low price among carbon fillers. Nevertheless, the relationship between the volume expansion (≈interlayer spacing) of EG and the thermal conductivity of EG filled composites has been rarely reported on. We designed and developed an inductively coupled plasma (ICP) for the rapid expansion of a expandable graphite precursor. Greater extent of volume expansion of EG was observed at higher ICP treatment temperature and the thermal conductivity of the composites was increased with the expanded volume of the filler, at the same filler content. Based on a quantitative analysis on filler size within the composites using non-destructive micro-computed tomography, larger size of three dimensional (3D) thermally conductive filler networks with respect to the volume expansion were obviously confirmed. Excellent thermal conductivity (the highest value of 10.77 W/m·K) and heat dissipation characteristic of the composites were derived when the 3D thermally conductive EG filler network was generated at a larger size. These findings can contribute to realizing effective and low-priced thermally conductive carbon filler based polymer composites.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • High-strength carbon nanotube fibers by twist-induced self-strengthening
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Yuanyuan Shang, Ying Wang, Shuhui Li, Chunfei Hua, Mingchu Zou, Anyuan Cao
      High-strength carbon nanotube (CNT) fibers are strongly desired as they offer both excellent mechanical and electrical properties compared to traditional fiber materials. Here, we adopt twisting and compression as two complementary steps to tailor the fiber structure and obtain extraordinary mechanical properties. We have fabricated twist-compressed ribbon-like CNT fibers with predefined, uniform, relative large ribbon thicknesses (9–20 μm). Tensile tests show highly reproducible mechanical behavior of our fibers with a distinct self-strengthening stage during loading, leading to ultimate strengths up to 3.3–3.7 GPa in 9 μm-thick fibers at a gauge length of 10 mm, and strengths of 2.5–3.0 GPa at the same thickness but larger gauge length (100 mm). Whereas the compression step effectively reduces the cross-sectional area, twist-aligned CNTs and their re-orientation are responsible for producing large Poisson's ratio and achieving high strength. Controlled fabrication of thick, uniform, high-strength CNT fibers is critical for high load-bearing capacity and will facilitate many practical applications.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Ternary graphitic carbon nitride/red phosphorus/molybdenum disulfide
           heterostructure: An efficient and low cost photocatalyst for
           visible-light-driven H2 evolution from water
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Hui Zhao, Shengnan Sun, Yun Wu, Pingping Jiang, Yuming Dong, Zhichuan J. Xu
      Graphitic carbon nitride (g-C3N4) is a low cost photocatalyst for visible-light-driven H2 evolution from water. However, it faces the issue of rapid charge recombination that significantly suppresses the photocatalytic activity. Herein, we report a novel strategy in which low cost red phosphorus (RP) photocatalyst and molybdenum disulfide (MoS2) cocatalyst are co-introduced to accelerate photogenerated charge separation and transfer of g-C3N4. The g-C3N4/RP/MoS2 ternary composites are prepared by a step-by-step deposition method on g-C3N4 surface. Under the irradiation of visible light, the peak H2 evolution rate of 257.9 μmol g−1 h−1 is obtained when the loaded amounts of RP and MoS2 are 3.18 and 0.52 wt% (g-C3N4/RP-3.18/MoS2-0.52), respectively. When compared with pure g-C3N4 and g-C3N4/RP-3.18 in terms of H2 evolution activity, g-C3N4/RP-3.18/MoS2-0.52 demonstrates approximately 859.7 and 4.4 times, respectively. The loading of RP inhibits charge recombination of g-C3N4 due to the matched energy band position, the photoexcitation of RP itself increases total charge amount, as well as the presence of MoS2 accelerates charge separation and transfer of g-C3N4/RP-3.18. These cooperative effects make g-C3N4/RP-3.18/MoS2-0.52 exhibit an enhanced activity. We believe that this study is meaningful for building novel efficient and low cost g-C3N4 based heterostructure photocatalysts.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
  • Effect of carbonization conditions of polyaniline on its catalytic
           activity towards ORR. Some insights about the nature of the active sites
    • Abstract: Publication date: August 2017
      Source:Carbon, Volume 119
      Author(s): Javier Quílez-Bermejo, Carolina González-Gaitán, Emilia Morallón, Diego Cazorla-Amorós
      N-doped carbon materials were obtained using polyaniline (PANI) as precursor. Heat treatment of PANI and de-doped PANI (PANId) was performed using different temperatures −600 and 800 °C–. Two different atmospheres were used during the treatment: an inert atmosphere (N2) and another one consisting on a slightly oxidizing mixture of gases (3000 ppm O2 in N2). The prepared materials at 800 °C showed high values of capacitance, up to 170 and 255 F g−1 in basic and acid electrolytes, respectively, in spite of their low surface area. The electrocatalytic activity towards oxygen reduction reaction (ORR) of all materials was studied in basic and acid media. The heat treated materials at 600 °C did not show a good electrocatalytic activity due to their poor electrical conductivity. On the other hand, heat-treated materials at 800 °C showed an enhanced catalytic activity due to their higher conductivity and the presence of nitrogen and oxygen functionalities in the carbon surface. Interestingly, the heat treatment at 800 °C using a slightly oxidant atmosphere produces carbon materials with much higher ORR activity which seems to be related to the larger amount of N-edge and O-edge sites. Preliminary computational studies suggest that the presence of these nitrogen and oxygen functionalities in the vicinities of the carbon atom improves the catalytic performance of N-doped carbon materials in the ORR and that two adjacent active sites can produce the O2 reduction to H2O through a 4 electrons pathway.
      Graphical abstract image

      PubDate: 2017-04-17T14:21:19Z
       
 
 
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