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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (51 journals)
    - CHEMISTRY (596 journals)
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CHEMISTRY (596 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: 246)
ACS Photonics     Full-text available via subscription   (Followers: 12)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
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 Chimica Slovenica     Open Access  
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)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
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: 15)
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: 39)
Angewandte Chemie     Hybrid Journal   (Followers: 220)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 223)
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: 16)
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: 22)
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: 318)
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: 120)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 84)
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: 5)
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: 15)
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: 25)
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: 182)
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: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
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: 153)
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: 42)
Chemistry of Materials     Full-text available via subscription   (Followers: 228)
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: 14)
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: 11)
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)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
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: 62)
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  

        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  [3089 journals]
  • Metal sputtered graphene based hybrid films comprising tin oxide/reduced
           graphene oxide/Ni as electrodes for high-voltage electrochemical
           capacitors
    • Abstract: Publication date: April 2018
      Source:Carbon, Volume 129
      Author(s): Segi Byun, Byungha Shin, Jin Yu
      The high voltage aqueous electrochemical capacitor (EC) is a promising energy storage device because of eco-friendliness and high electrochemical performance with a wide operational voltage and high energy density. However, it typically experiences a stability problem that includes cell aging and capacitance loss. Here, to overcome the stability issue, a thin metal layer of Ni is created on one side of a SnO2/reduced graphene oxide (rGO) hybrid film to produce a binder-free film of SnO2/rGO/Ni. Due to the formation of the highly conductive metal layer of Ni, the fabricated film can be well interconnected with the current collector and have lower contact resistance and open-circuit potential compared with untreated SnO2/rGO film, which results in a remarkable enhancement of electrochemical performance, including a wide operational voltage (1.8 V), semi-permanent cycle-life (95% retention after 10k cycles), and ultrahigh volumetric energy density with a high power density, all of which are superior values compared to bare SnO2/rGO film based devices. We anticipate that the fabricated SnO2/rGO/Ni film could be utilized as a promising electrode for high voltage ECs, and our simple surface engineering technique will provide an effective electrode design for the fabrication of high performance thin-film ECs.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • A multi-technique experimental and modelling study of the porous structure
           of IG-110 and IG-430 nuclear graphite
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Katie L. Jones, Giuliano M. Laudone, G. Peter Matthews
      In nuclear graphite, the wide range of void sizes precludes a full characterisation of pore volume by means of a single technique. A novel multi-technique approach, consisting of pycnometry, low pressure gas adsorption and mercury porosimetry is presented. The approach is validated for two nuclear-grade graphites designed for use in Generation IV nuclear reactors, namely IG-110 and IG-430. Damage and deformation caused to the structure of the graphite by mercury intrusion is estimated by consecutive intrusion experiments. The damage is assumed to be caused by the highest applied pressures of mercury. It is compensated by substituting that part of the percolation curve with one derived from adsorption measurements. The various measurements are inverse modelled in a way which intelligently bridges the size gap between the techniques. The resulting complete non-hierarchical pore structure covers sizes spanning 4 orders of magnitude. The new approach resolves the long standing issues associated with performing porosimetry on graphitic samples, and fills the gap in knowledge for the assessment of multilevel porosity within graphite. As an example of the possible applications of the resulting void network structure, we calculated the air network flow capacity, related to absolute permeability, for the two graphite samples.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • White-emitting carbon dots with long alkyl-chain structure: Effective
           inhibition of aggregation caused quenching effect for label-free imaging
           of latent fingerprint
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Bang-Ping Jiang, Yun-Xiang Yu, Xiao-Lu Guo, Zhao-Yang Ding, Bo Zhou, Hong Liang, Xing-Can Shen
      The surface functionalization of carbon dots (CDs) can introduce an additional dimension for the control of their photoluminescence properties and effective promotion of the applications of CDs such as imaging, sensing, etc. In this study, a simple one-step carbonization using Tween 80 as the sole carbon source is described for directly synthesizing white-emitting CDs (WCDs) in high yield. The results revealed the presence of several long alkyl chains on the surface of the as-fabricated WCDs, which effectively suppress the aggregation-caused quenching (ACQ) effect and emit bright white luminescence under an UV illumination of 365 nm in the solution and solid states. Besides, together with the surface protection of long alkyl chains, WCDs preferentially interact with lipophilic fatty residues and are beneficial for the label-free imaging of latent fingerprints. This study provides a promising new method to not only effectively inhibit the intrinsic ACQ effect of CDs but also develop the surface engineering of functionalized white-emitting CDs for practical applications via facile synthesis.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Mesocrystalline Ti3+TiO2 hybridized g-C3N4 for efficient visible-light
           photocatalysis
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Xin Yu, Xiaoli Fan, Li An, Guangbo Liu, Zhonghua Li, Jiawen Liu, PingAn Hu
      TiO2 mesocrystals are often considered to be a fascinating and efficient photocatalyst because of its long lifetime carriers and effective conduction pathways. However, TiO2 mesocrystals showed no visible light response and visible light photocatalytic activity. To overcome these shortages, mesocrystalline Ti3+ TiO2 (meso-TiO2) and its composites are highly desired to have strong capacity for harvesting visible light and photocatalytic hydrogen production. In this work, Ti3+ doped TiO2 mesocrystals were successfully prepared through oriented attachment mechanisms, and direct Z-scheme Ti3+ self-doped TiO2 mesocrystals/g-C3N4 composites were also prepared by facile solvethermal method. The as-prepared Ti3+ TiO2 mesocrystals showed visible light absorption and photocatalytic activity for hydrogen production. Interestingly, the as-prepared Ti3+ doped meso-TiO2/g-C3N4 composites displayed highly improved visible light absorption and visible light photocatalytic activity for hydrogen production, and the highest photocatalytic activity for hydrogen production was about 3748.46 μmol g−1 h−1 with an apparent quantum efficiency of 1.42% at 400 nm (sacrificial agent, triethanolamine) and 983.56 μmol g−1 h−1 (sacrificial agent, methanol), much higher than that of g-C3N4 and Ti3+ doped TiO2 mesocrystals, mainly due to the high charge separation efficiency, long lifetime carriers and effective transport pathways. Finally, possible direct Z-scheme photocatalytic mechanism of Ti3+ doped meso-TiO2/g-C3N4 composites were proposed in detail.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • A novel approach for forming carbon nanorods on the surface of carbon felt
           electrode by catalytic etching for high-performance vanadium redox flow
           battery
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Saleem Abbas, Hyuck Lee, Jinyeon Hwang, Asad Mehmood, Hyun-Jin Shin, Sheeraz Mehboob, Ju-Young Lee, Heung Yong Ha
      In this work a novel method is unfolded to modify carbon felts (CF) to substantially improve the performance of the electrodes for vanadium redox flow batteries (VRFBs). The carbon felt, a well-known electrode material for VRFB, is catalytically etched by cobalt oxide to form carbon nanorods on the surface of the fibers comprising the CF. Unlike conventional multistep processes to grow nano-structures on carbon felts, this method simply involves a thermal treatment of catalyst-loaded felt in air to produce well aligned nanorods on its fibers. The surface morphology is optimized by etching temperature, treatment time and catalyst type. The catalytically etched CF shows an improved surface wettability and an enlarged specific surface area about two times compared to pristine CF that lead to an improvement of kinetics towards vanadium redox reactions. When used as electrode in all-vanadium redox flow battery, the nanorod-structured CF shows around 35% higher charge/discharge rate capability at 150 mA cm−2 and 80% retained-capacity compared to 48% in case of un-etched CF as confirmed by a long run test with a hundred cycles of charge/discharge operation at 50 mA cm−2.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Fabricating Pt-decorated three dimensional N-doped carbon porous
           microspherical cavity catalyst for advanced oxygen reduction reaction
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Yaru Cheng, Huiting Lu, Kai Zhang, Fan Yang, Wenhao Dai, Conghui Liu, Haifeng Dong, Xueji Zhang
      Abundant and low-cost materials with high electrochemical catalytic activity for oxygen reduction reaction (ORR) are in urgent demand for energy storage and conversion devices. In this work, an advanced ORR electrocatalyst of Pt-decorated three dimensional (3D) N-doped carbon porous microspherical cavity (PtN/C PMC) was fabricated by using polystyrene microspheres (PS) as template, and dopamine and K2PtCl6 as precursors. Microscopic and spectroscopic characterizations revealed large surface area available and affluent pore structures were observed in the resulted PtN/C PMCs, and numerous Pt nanoparticles (NPs) with active (111) facet were decorated on the surface of N/C PMCs. The proposed PtN/C CMCs presented good onset potential, remarkable mass activity (MA) and specific activity (SA), superb methanol tolerance and excellent durability toward ORR in alkaline solutions. The numerous decorated Pt with high active (111) facet coupled with high content of active pyridinic and graphitic nitrogen synergistically contributed to the enhanced ORR activity, while the unique 3D porous structures facilitated O2 and electrolyte transport during the ORR process. This work may open new avenue for designing advanced and cost-effective Pt-based ORR catalyst.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Nest-like assembly of the doped single-walled carbon nanotubes with unique
           mesopores as ultrastable catalysts for high power density Zn-air battery
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Qiangmin Yu, Chuxin Wu, Jiaoxing Xu, Yi Zhao, Jianshuo Zhang, Lunhui Guan
      Uniform nest-like structures with high surface areas and unique pore sizes were prepared by self-assembly of the oxidized single-walled carbon nanotubes (SWCNT). After doping with cobalt and nitrogen, the assembly exhibited much higher electrocatalytic activity for the oxygen reduction reaction than the commercial Pt/C catalyst. Benefited from effective exposing the active sites and sufficient diffusion pathways of O2 for fast reaction kinetic, when used as the air electrode catalysts for a Zn-air battery, the power density constructed by the assembly reached as high as 248 mW cm−2 under the high current density of 330 mA cm−2, superior to that of Pt/C air-cathode (195 mW cm−2) and other non-precious metal catalysts ever reported.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Transformation of C60 fullerene aggregates suspended and weathered under
           realistic environmental conditions
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Josep Sanchís, Yann Aminot, Esteban Abad, Awadhesh N. Jha, James W. Readman, Marinella Farré
      The occurrence, fate and behaviour of carbon nanomaterials in the aquatic environment are dominated by their functionalization, association with organic material and aggregation behaviour. In particular, the degradation of fullerene aggregates in the aquatic environment is a primary influence on their mobility, sorption potential and toxicity. However, the degradation and kinetics of water suspensions of fullerenes remain poorly understood. In the present work, first, an analytical method based on liquid chromatography and high-resolution mass spectrometry (LC-HRMS) for the determination of C60 fullerene and their environmental transformation products was developed. Secondly, a series of C60 fullerene water suspensions were degraded under relevant environmental conditions, controlling the salinity, the humic substances content, the pH and the sunlight irradiation. Up to ten transformation products were tentatively identified, including epoxides and dimers with two C60 units linked via one or two adjacent furane-like rings. Fullerenols were not observed under these environmentally relevant conditions. The kinetics of generation of each transformation product were studied with and without simulated sunlight conditions. The ionic strength of the media, its pH and the humic substances content were observed to modulate the kinetics of generation.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Tubular titanium oxide/reduced graphene oxide-sulfur composite for
           improved performance of lithium sulfur batteries
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Junhua Song, Jianming Zheng, Shuo Feng, Chengzhou Zhu, Shaofang Fu, Wengao Zhao, Dan Du, Yuehe Lin
      Lithium sulfur (LiS) batteries are promising alternatives to conventional Li-ion batteries in terms of specific capacity and energy. However, the technical challenges raised from the soluble polysulfide (PS) in organic electrolyte deter their implementation in practical applications. Nanoengineered structure and chemical adsorptive materials hold great promise in mitigating the PS migration problem. Here, we develop a tubular titanium oxide (TiO2)/reduced graphene oxide (rGO) composite structure (TG) as a sulfur hosting material for constructing better performed LiS batteries. The TG/sulfur cathode (TG/S) is able to deliver ∼1200 mAh g−1 specific capacity with stable operation for over 550 cycles. Moreover, the TG/S composite cathode shows stable Coulombic efficiencies of over ∼95% at various C rates, which are ∼10% higher than those of the rGO/sulfur (G/S) counterparts. The superior electrochemical performances of TG/S could be ascribed to the synergistic effects between the conductive rGO support and the physically/chemically absorptive TiO2, that is, the spatial tubular structure of TiO2 provides intimate contact and physical confinement for sulfur, while the polar TiO2 in TG/S shows strong chemical interaction towards the sulfur species.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Surface-enhanced Raman scattering of graphene caused by self-induced
           nanogating by GaN nanowire array
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): J. Kierdaszuk, P. Kaźmierczak, R. Bożek, J. Grzonka, A. Krajewska, Z.R. Zytkiewicz, M. Sobanska, K. Klosek, A. Wołoś, M. Kamińska, A. Wysmołek, A. Drabińska
      A constant height of gallium nitride (GaN) nanowires with graphene deposited on them is shown to have a strong enhancement of Raman scattering, whilst variable height nanowires fail to give such an enhancement. Scanning electron microscopy reveals a smooth graphene surface which is present when the GaN nanowires are uniform, whereas graphene on nanowires with substantial height differences is observed to be pierced and stretched by the uppermost nanowires. The energy shifts of the characteristic Raman bands confirms that these differences in the nanowire height has a significant impact on the local graphene strain and the carrier concentration. The images obtained by Kelvin probe force microscopy show clearly that the carrier concentration in graphene is modulated by the nanowire substrate and dependent on the nanowire density. Therefore, the observed surface enhanced Raman scattering for graphene deposited on GaN nanowires of comparable height is triggered by self-induced nano-gating to the graphene. However, no clear correlation of the enhancement with the strain or the carrier concentration of graphene was discovered.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • Carbon dots with red-shifted photoluminescence by fluorine doping for
           optical bio-imaging
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Wanning Yang, Hong Zhang, Junxin Lai, Xinyi Peng, Yuping Hu, Wei Gu, Ling Ye
      Carbon dots (CDs) are environmentally benign alternatives to quantum dots comprised of heavy metals with outstanding photoluminescent (PL) properties and have shown great promise in optical bio-imaging and sensing. However, it remains challenging to rationally design and synthesize CDs with red PL emission. We herein disclose that a red-shifted PL emission could be achieved by doping the electron-withdrawing fluorine atoms into CDs. Moreover, we demonstrate the preparation of fluorine doped CDs with a red PL emission under excitation at 530 nm by an easy, environmental friendly, one-step microwave-assistant carbonation route. A possible mechanism of the red-shifted emission upon fluorine doping is tentatively proposed. In addition, the applicable of these red-emissive fluorine doped CDs as optical nanoprobes for bio-imaging applications, both in vivo and in vitro, was explored. It is indicated that the as-prepared fluorine doped CDs with red-shifted PL emission are promising candidates for tumor bio-imaging/or diagnostics.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Accelerated polysulfide redox kinetics revealed by ternary sandwich-type
           S@Co/N-doped carbon nanosheet for high-performance lithium-sulfur
           batteries
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Mei-e Zhong, Jindiao Guan, Qiuju Feng, Xiongwei Wu, Zhubing Xiao, Wei Zhang, Shuai Tong, Nan Zhou, Daoxin Gong
      Lithium-sulfur (Li-S) batteries show significant advantages for next-generation energy storage systems due to the high theoretical energy density and cost effectiveness. The main challenge for developing long-life and high-performance Li-S batteries is to simultaneously restrain the shuttle of soluble polysulfides while accelerating the redox kinetics of sulfur-related species during cell operation. Herein, a sandwich-type sulfur@Co/N-doped carbon (S@Co-NC) ternary composite is synthesized, combining in a simple way the advantages of synergetic physical and chemical confinement on sulfur-related species. A further electrochemical redox kinetic study confirms that the incorporated conductive Co mediators and doped N species serve as dual electrocatalysts, substantially accelerating the kinetics of the polysulfide redox reactions. By relieving the sluggishness of polysulfide redox reactions, the as-obtained sandwich-type S@Co-NC composite has significantly promoted electrochemical performance including enhanced rate capability, lower polarization and higher Coulombic efficiency. It delivers extremely high discharge capacity of 1401 mAh g−1 at 0.05 C with an area sulfur loading of 1.3 mg cm−2. More importantly, the ternary electrode retains a high rate capability of 694 mAh g−1 over extensive 600 cycles at 1 C, with nearly 100% Coulombic efficiency maintenance. These results suggest that the S@Co-NC ternary composite provides possibility of realizing the industrially practical Li-S batteries.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Self-terminated activation for high-yield production of N,P-codoped
           nanoporous carbon as an efficient metal-free electrocatalyst for Zn-air
           battery
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Hao Luo, Wen-Jie Jiang, Yun Zhang, Shuai Niu, Tang Tang, Lin-Bo Huang, Yu-Yun Chen, Zidong Wei, Jin-Song Hu
      To enhance the electrocatalytic activity of heteroatom doped carbon for oxygen reduction reaction (ORR), high surface area and favorable porous structure are commonly required for providing sufficient accessible active sites. However, these features usually come with the severe carbon loss during pyrolysis and activation process. Herein, we report a facile self-terminated activation strategy for high-yield production of nitrogen and phosphorus codoped nanoporous carbon (NP-NC) by using potassium phytate as carbonaceous source. The in-situ formed potassium species enable the effective carbon activation to create plenty of nanopores without additional corrosive chemicals while the formation of K4P2O7 properly terminates the activation, resulting in the extremely low weight loss less than 17%. Benefited from the high surface area of 1294 m2 g−1 and trimodal nanoporous structure, the resulted N, P-codoped catalyst exhibits superior ORR activity close to Pt/C, high catalytic current density as well as excellent methanol tolerance and durability. Importantly, as cathode catalyst for Zn-air battery, N,P-NC also exhibits current and power densities comparable to the state-of-the art 20% Pt/C. Therefore, such a facile, scalable and high-yield synthesis of N,P-codoped nanoporous carbon materials opens up opportunities for the mass-production of highly efficient cost-effective electrocatalysts for energy applications.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Design and synthesis of macroporous (Mn1/3Co2/3)O-carbon nanotubes
           composite microspheres as efficient catalysts for rechargeable Li-O2
           batteries
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Jung Hyun Kim, Yeon Jong Oh, Yun Chan Kang
      Unique-structured (Mn1/3Co2/3)O-carbon nanotubes (MnCoO-CNT) composite microspheres synthesized by one-pot spray pyrolysis were studied as air electrode for lithium–oxygen (Li-O2) batteries. The (Mn1/3Co2/3)O nanocrystals were first introduced as efficient electrocatalysts for oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs). In addition, the optimum structure of CNT microspheres was designed as efficient support material for (Mn1/3Co2/3)O nanocatalysts with high electrical conductivity and high accommodation ability for Li2O2 products. The macroporous MnCoO-CNT composite microspheres exhibited excellent bifunctional oxygen catalytic activities in terms of a positive half-wave potential (0.67 V) for ORRs and high limiting diffusion current (35 mA cm−2 at 1.0 V) for OERs. When applied as a cathode material for Li–O2 batteries, the MnCoO–CNT microspheres delivered a high discharge capacity (37142 mA h g−1 at 200 mA g−1), excellent rate capability (4458 mA h g−1 at 2000 mA g−1), and long-term cycle stability (245 cycles at a capacity of 500 mA h g−1 at 200 mA g−1). The synergetic effect of macroporous CNT microspheres with high electrical conductivity and high electrocatalytic activities of the (Mn1/3Co2/3)O nanocatalyst were responsible for the superior performance of MnCoO–CNT composite microspheres as cathode material for Li–O2 batteries.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Amphiphilic mesoporous graphene mediated efficient photoionic cell
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Yujie Liu, Jingjing Xiao, Liang Qiao, Baohong Liu
      Photoionic cell is a facile concept for direct solar energy conversion and storage based on dye-quencher couples. We propose a system based on dye modified amphiphilic mesoporous graphene (APG) and cobalt EDTA as a photoionic cell. Upon light irradiation, the dyes are excited and quenched by cobalt EDTA in aqueous solution to form oxidized cobalt EDTA and reduced dyes that are hydrophobic. Solar energy is then converted into electrochemical energy in the form of the oxidized cobalt EDTA in aqueous solutions and reduced dyes in APG. Compared to organic phase usually used for photoionic cells, the usage of APG can lead to increased amount of dye molecules in the photoionic cells, and can achieve approximately 100% separation of the reduced dyes from the oxidized cobalt EDTA for long term energy storage.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Root-like porous carbon nanofibers with high sulfur loading enabling
           superior areal capacity of lithium sulfur batteries
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Xiaohui Zhao, Miso Kim, Ying Liu, Hyo-Jun Ahn, Ki-Won Kim, Kwon-Koo Cho, Jou-Hyeon Ahn
      A hierarchically porous carbon nanofiber (HPCNF) material was prepared by a facile electrospinning method, with polyvinylpyrrolidone (PVP) as the carbon source and silica formed in-situ as the template. The carbon nanofibers showed a well-designed pore structure: centered macropores are surrounded by a denser cycle consisting of micro-/mesopores near the surface. Sulfur was encapsulated into the pores by solution penetration, followed by a melt diffusion method to generate a flexible sulfur/HPCNF (S/HPCNF) cloth as the binder-free cathode in lithium sulfur (Li-S) batteries. The HPCNF carbon with multi-scaled pores acts as an efficient host for large amounts of sulfur, and accommodates the associated volume expansion during electrochemical cycling. Moreover, the hierarchical architecture significantly reduces the escape of polysulfides during the cycling. The unique material allowed sulfur loading of 2.2–12.1 mg cm−2, and exhibited a high sulfur utilization of more than 80% with high areal capacity of 11.3 mAh cm−2, demonstrating that S/HPCNF is a promising cathode material for Li-S batteries of high energy density.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Nitrogen doped heat treated and activated hydrothermal carbon: NEXAFS
           examination of the carbon surface at different temperatures
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Kenneth G. Latham, Wesley M. Dose, Jessica A. Allen, Scott W. Donne
      Hydrothermal carbons have been shown to have controllable surface functionalization through various post-treatment techniques, which indicates these materials may be tuned for specific applications. For this reason, Near Edge X-ray Absorption Fine Structure (NEXAFS) studies have been conducted on a series of nitrogen doped and non-doped heat treated and activated hydrothermal carbons to further understand the changes in surface functionality with treatment. The NEXAFS carbon K-edge spectrum of the non-doped samples displayed a loss of oxygen functionalities (CO and COH) as well as the furan ring structure with increasing temperature, while CC bonds from graphitic groups increased. This effect was amplified further upon the addition of phosphoric acid (H3PO4) during activation. The doped hydrothermal carbons displayed similar functionality to the non-doped, although the effect of both heat treatment and activation was diminished. The nitrogen K-edge displayed characteristic peaks for pyridine and imines/amides, with pyrroles located under the broad ionization step. This work represents the first time a series of heat treated and activated hydrothermal carbons have been examined via NEXAFS spectroscopy. Additionally, difference analysis has been applied to the NEXAFS spectra to obtain a deeper understanding in the changes in surface functionality, a previously unused technique for these materials.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Carbons from biomass precursors as anode materials for lithium ion
           batteries: New insights into carbonization and graphitization behavior and
           into their correlation to electrochemical performance
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Olga Fromm, Andreas Heckmann, Uta C. Rodehorst, Joop Frerichs, Dina Becker, Martin Winter, Tobias Placke
      We report a comprehensive and systematic study on the preparation and characterization of carbonaceous materials that are obtained from five different sustainable precursor materials and petroleum coke as reference material, particularly focusing on the correlation between the structural transformation of the precursors into carbons in dependence of heat treatment temperature (HTT) and their corresponding electrochemical characteristics as anode material in lithium ion batteries. The carbons were carbonized and graphitized in 200 °C steps, covering a broad temperature range from 800 °C to 2800 °C. So far, such a systematic synthesis approach has not been reported in literature. For biomass-derived carbons, we found a heterogeneous (discontinuous) graphitization process, i.e. a transformation from the amorphous to the graphitic phase via the turbostratic phase. A general trend was observed for the discharge capacity, i.e. a decrease of capacity from 800 °C to ≈1800–2000 °C, followed by an increase of capacity for temperatures >2000 °C. An increase of the 1st cyle Coulombic efficiency was found and could be directly correlated to the decrease of the “non-basal plane” surface area upon HTT. In addition, we found that the voltage efficiency and energy efficiency of the different carbons also increase with rising treatment temperatures.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Three-dimensional macroporous CNTs microspheres highly loaded with NiCo2O4
           hollow nanospheres showing excellent lithium-ion storage performances
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Gi Dae Park, Jung-Kul Lee, Yun Chan Kang
      Three-dimensional macroporous carbon nanotubes microspheres highly loaded with phase-pure NiCo2O4 hollow nanospheres are synthesized by the spray pyrolysis process and are characterized for potential use in lithium-ion batteries. Polystyrene nanobead template and the nanoscale Kirkendall diffusion process are first combined and are applied to the spray pyrolysis process to form macroporous NiCo2O4/carbon nanotubes composite microspheres with extremely high rate performance as anode materials for lithium-ion batteries. Metallic NiCo2/carbon nanotubes composite microspheres—formed as intermediate products—are transformed into composite microspheres of phase-pure NiCo2O4 hollow nanospheres and carbon nanotubes by the nanoscale Kirkendall diffusion process. The mean size of the hollow NiCo2O4 nanospheres decorated on the carbon nanotubes backbone is 28 nm. The macroporous NiCo2O4/carbon nanotubes composite microspheres have discharge capacities of 840, 748, 677, 591, 514, 451, 391, 337, and 289 mA h g−1 at current densities of 0.5, 1, 2, 5, 10, 15, 20, 25, and 30 A g−1, respectively. The discharge capacity of the macroporous NiCo2O4/carbon nanotubes microspheres for the 500th cycle at a current density of 3 A g−1 is 572 mA h g−1. The uniquely structured hollow NiCo2O4 nanosphere/carbon nanotubes composite microspheres have superior cycling and rate performances for lithium-ion storage.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Superior potassium storage in chitin-derived natural nitrogen-doped carbon
           nanofibers
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Rui Hao, Hao Lan, Chengwei Kuang, Hua Wang, Lin Guo
      Potassium ion batteries (KIBs) are drawing intensive attention as the next-generation energy storage technology, owning to their similar electrochemical properties to lithium system and rich abundance of potassium resources. The carbonaceous materials with low cost, nontoxicity and high safety have been considered as promising candidates for KIBs anodes. However, they still suffer from several problems, such as poor cycling and rate capability, complex activation process steps and multiple procedures to import heteroatoms doping. Herein, the N-doped carbon nanofibers (NCFs) are fabricated by direct pyrolysis of bio-waste chitin, which is the second most abundant biopolymer throughout nature. The as-prepared NCFs used as KIBs anodes, without any additional activation steps, are systematically investigated for the first time. They deliver high capacity, excellent rate capability and long-term cycling stability, which benefit from the multiple synergistic effects of suitable interlayer spacing, heteroatom doping and unique one dimensional mesoporous structure. With the spotlight of environmental friendliness, low cost and high energy density in energy storage field, the chitin-based NCFs demonstrate great potential for future low-cost energy storage applications.
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      PubDate: 2017-12-13T07:15:05Z
       
  • Glass composites reinforced with silicon-doped carbon nanotubes
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Jianxin Lu, Ming Luo, Boris I. Yakobson
      Glass composite reinforcement by addition of carbon nanotubes (CNTs) is limited due to generally poor load transfer between the matrix and “slippery” reinforcing element. Using computational methods, here we investigate how this load transfer challenge can be overcome by doping the CNT walls with silicon atoms, to create a novel high performance glass composite reinforced with such silicon-doped CNTs (Si-CNTs). It is shown, from first-principles density functional calculations, how silicon dopants in the CNTs should covalently bind with oxygen atoms from the SiO2-glass, resulting in strong interfacial bonding and effective load transfer between the CNTs and the matrix. Molecular dynamics (MD) simulations of this new Si-CNTs reinforced glass composite reveal both ∼10 times increase of the interfacial traction and up to 60% increase of the Young's modulus. A modified shear-lag model is derived, for predicting the composite's Young's modulus, for finite-length CNTs in matrices, as a function of the interfacial strength, the CNT aspect ratio, and the silicon-dopant concentration. The model can also be extended to other similar short-fiber composites.
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      PubDate: 2017-12-13T07:15:05Z
       
  • 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.
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      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.
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      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.
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      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.
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      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.
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      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°.
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      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.
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      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.
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      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.
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      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.
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      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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
       
 
 
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