for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> CHEMISTRY (Total: 852 journals)
    - ANALYTICAL CHEMISTRY (52 journals)
    - CHEMISTRY (598 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (69 journals)

CHEMISTRY (598 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 10)
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: 38)
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: 252)
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: 57)
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: 18)
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: 66)
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: 179)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 229)
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   (Followers: 1)
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: 326)
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: 85)
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: 68)
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: 5)
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: 70)
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: 21)
Chemical Reviews     Full-text available via subscription   (Followers: 184)
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: 146)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 42)
Chemistry of Materials     Full-text available via subscription   (Followers: 246)
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: 10)
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: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 19)
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: 18)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 64)
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]   [68 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6223
   Published by Elsevier Homepage  [3118 journals]
  • Lateral heterostructures of two-dimensional materials by electron-beam
           induced stitching
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Andreas Winter, Antony George, Christof Neumann, Zian Tang, Michael J. Mohn, Johannes Biskupek, Nirul Masurkar, Arava Leela Mohana Reddy, Thomas Weimann, Uwe Hübner, Ute Kaiser, Andrey Turchanin
      We present a novel methodology to synthesize two-dimensional (2D) lateral heterostructures of graphene and MoS2 sheets with molecular carbon nanomembranes (CNMs), which is based on electron beam induced stitching. Monolayers of graphene and MoS2 were grown by chemical vapor deposition (CVD) on copper and SiO2 substrates, respectively, transferred onto gold/mica substrates and patterned by electron beam lithography or photolithography. Self-assembled monolayers (SAMs) of aromatic thiols were grown on the gold film in the areas where the 2D materials were not present. An irradiation with a low energy electron beam was employed to convert the SAMs into CNMs and simultaneously stitching the CNM edges to the edges of graphene and MoS2, therewith forming a heterogeneous but continuous film composed of two different materials. The formed lateral heterostructures possess a high mechanical stability, enabling their transfer from the gold substrate onto target substrates and even the preparation as freestanding sheets. We characterized the individual steps of this synthesis and the structure of the final heterostructures by complementary analytical techniques including optical microscopy, Raman spectroscopy, atomic force microscopy (AFM), helium ion microscopy (HIM), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) and find that they possess nearly atomically sharp boundaries.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Crumpled graphene prepared by a simple ultrasonic pyrolysis method for
           fast photodetection
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Zhenfei Gao, Zhiwen Jin, Qingqing Ji, Yushu Tang, Jing Kong, Liqiang Zhang, Yongfeng Li
      In the past decades, graphene has attracted much attention as the host material of photodetectors (PDs), owing to its fascinating mechanical property, ultrahigh carrier mobility and remarkable optical transparency. However, the intrinsic low light absorption of graphene affects its comprehensive application in PDs. Therefore, graphene-based PDs research has focused on hybrid system and optimized graphene structures to enhance photoabsorption. In order to combine the advantages of both approaches, we successfully prepared crumpled reduced graphene oxide (C-rGO) for PDs by a simple ultrasonic pyrolysis method. Through this rapid, one-step capillary-driven route, C-rGO and C-rGO/(ZnO,PbS) composite films can be easily deposited on arbitrary substrates (PET, glass, Al2O3 ceramic and paper). Interestingly, the unique C-rGO PDs shows superior stability and fast transient photocurrent response (rise/decay time of 189/189 ms). Furthermore, by incorporating ZnO and PbS nanoparticles to enhance light absorption, the crumpled hybrid nanostructure PDs demonstrate about four times increased photocurrents and broad-band (UV–Vis–NIR) photodetection features with R of 0.12 A/W. Such crumpled C-rGO-based PDs hold great potentials for future optoelectronic applications, and the ultrasonic pyrolysis method could open a new way for engineering novel nanostructured thin films with high-performance photodetection.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Precursor gas composition optimisation for large area boron doped
           nano-crystalline diamond growth by MW-LA-PECVD
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): A. Taylor, P. Ashcheulov, P. Hubík, L. Klimša, J. Kopeček, Z. Remeš, Z. Vlčková Živcová, M. Remzová, L. Kavan, E. Scheid, J. Lorinčík, V. Mortet
      We report on the optimisation of precursor gas composition for the repeatable preparation of large area highly conductive boron doped nano-crystalline diamond layers with low sp2 content using microwave plasma enhanced linear antenna chemical vapour deposition apparatus. The precursor gas composition parameter space was probed by varying the boron, oxygen and carbon atomic ratios whilst fixing all other parameters constant. By radically increasing the B content and careful consideration of the B and O content in the gas phase, thin B-NCD layers (∼300 nm) were prepared over large areas, repeatable, with high boron concentrations (∼2 × 1021 at/cm3) and electrical conductivity levels akin to B-NCD layers prepared in conventional MW PECVD systems (>35 S cm−1) with electrochemical properties suitable for industrial applications.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Scalable and site specific functionalization of reduced graphene oxide for
           circuit elements and flexible electronics
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Mahesh Soni, Pawan Kumar, Juhi Pandey, Satinder Kumar Sharma, Ajay Soni
      We demonstrate a rapid and facile approach towards scalable patterning of reduced graphene oxide (rGO) for interconnects in flexible electronic applications. We have used controlled UV light exposure for patterning of rGO over spin coated GO film, which has been demonstrated by various patterns of GO-rGO. Optical and conductivity contrast has been supported by spectroscopic data for GO and rGO regions. Electrical conductivity of completely exposed rGO (60 mS/m) is significantly (∼150 times) higher than unexposed GO, which is suggesting effectiveness of rGO for circuit elements and interconnect applications. The tunable GO reduction is used for fabrication of rGO-FET, on flexible substrates, with completely exposed rGO as source/drain/gate electrodes and partially exposed rGO as semiconducting channel. The site specific and large area patterning of GO-rGO is advantageous for its usage in lighter and wearable flexible electronics.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Improved long term cycling of polyazulene/reduced graphene oxide
           composites fabricated in a choline based ionic liquid
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Milla Suominen, Pia Damlin, Sari Granroth, Carita Kvarnström
      To improve the energy density of supercapacitors, novel electronically conducting polymers should be introduced to the research field. Polyazulene is a well-suitable candidate as it exhibits good capacitive behavior both in organic solvents as well as in various ionic liquids, but especially its long term cycling stability should be improved. Previously, enhanced properties have been obtained by combining conducting polymers with carbon nanomaterials to fabricate composites. This work presents an ionic liquid assisted electrochemical polymerization and characterization of polyazulene-reduced graphene oxide composites. The ionic liquid of our choice is choline-based liquid salt. We prepared stable dispersions of graphene oxide in this ionic liquid and performed potentiodynamic electropolymerization of azulene in the mixture. Changing the concentration of graphene oxide between 0.1 and 2 mg mL−1 had no remarkable effect on the polymerization or electrochemical behavior of the composite materials. The composites exhibit higher capacitances compared to neat polymer films determined by cyclic voltammetry and electrochemical impedance spectroscopy. The obtained films also exhibit excellent cycling stabilities retaining over 90% of their initial capacitance with tendency towards improved cycling stability when combined with reduced graphene oxide. The successful incorporation and reduction of graphene oxide was determined by several spectroscopic techniques.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • The influence of hydrogen on transition metal - Catalysed graphene
           nucleation
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): I. Mitchell, A.J. Page
      We demonstrate how hydrogen influences graphene nucleation on two archetypal catalysts, Cu(111) and Ni(111), using first-principles methods. The graphene nucleation mechanism is shown to be the result of the balance between the nature and strength of the carbon – metal interaction, and the influence of the hydrogen chemical potential on adsorbed carbon fragments. While the former drives the formation of ring structures in carbon fragments, the latter promotes the growth of saturated carbon chain structures during the nucleation process. Importantly, our results reveal how the presence of hydrogen dramatically influences the nature of the sp → sp2 transition, a key step in the nucleation of both graphene and carbon nanotubes. Increasing the presence of hydrogen during nucleation stabilises smaller ring structures earlier in the nucleation process, in fragments as small as carbon pentagons, which are known to be a key intermediate structure in carbon nanostructure nucleation. Conversely, lower hydrogen chemical potentials lead to the formation of carbon ring structures only in much larger fragments. These results present a new potential route by which hydrogen leads to greater control over CVD-synthesised carbon nanotubes and graphene, i.e. by driving the formation of smaller, more stable ring structures earlier in the growth process.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Effect of boron doping level on the photocatalytic activity of graphene
           aerogels
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Shamik Chowdhury, Yiqun Jiang, Solai Muthukaruppan, Rajasekhar Balasubramanian
      Heteroatom-doped three-dimensional (3D) graphene-based macroscopic assemblies (GMAs) are receiving considerable attention for application as heterogeneous photocatalysts. However, the relationship between the concentration and the bonding state of heteroatoms at the atomic scale and the resulting photoelectronic and photocatalytic properties of 3D GMAs remain unexplored. Herein, we describe a simple, environmentally benign, one-pot hydrothermal reduction-induced self-assembly process to prepare boron-doped graphene aerogels by using graphene oxide and boric acid as carbon (C) and boron (B) sources, respectively. By rationally adjusting the dopant elemental precursor, the B content was modulated from ∼0.14 to ∼3.37 at%. The as-synthesized B-doped bulk graphene monoliths with well-defined interconnected 3D porous networks can effectively degrade acridine orange (AO), a well-known recalcitrant and biologically toxic pollutant, under visible light irradiation. Particularly, the aerogel with a moderate B loading of ∼2.15 at% displayed a superior photodegradation efficiency of ∼98%, which is 2.13 times higher than the undoped material. The generation of oxygenated B derivatives, such as borinic esters and boronic acids, on the edge sites and defect regions of the 2D graphene building blocks was primarily responsible for the exceptional photocatalytic activity. Besides, these macroscale photocatalysts are highly stable and easily recyclable for practical applications.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Anchoring effect of Ni2+ in stabilizing reduced metallic particles for
           growing single-walled carbon nanotubes
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Maoshuai He, Xiao Wang, Lili Zhang, Qianru Wu, Xiaojie Song, Alexander I. Chernov, Pavel V. Fedotov, Elena D. Obraztsova, Jani Sainio, Hua Jiang, Hongzhi Cui, Feng Ding, Esko Kauppinen
      The suitability of the NiMgO catalyst as a catalyst in chiral-selective growth of single-walled carbon nanotubes (SWNTs) by chemical vapor deposition has been assessed. It reveals that catalyst calcination temperature plays an important role in affecting the catalyst performances. Using CO as the carbon precursor and a chemical vapor deposition reaction temperature of 600 °C, NiMgO pre-calcined at 600 °C demonstrates the best performances in catalyzing the growth of SWNTs with predominant (6, 5) species. Systematic characterizations on catalysts calcinated at different temperatures indicate that Ni2+ ions diffuse towards the interior of MgO matrix upon annealing. DFT-based calculations reveal that the binding energy between Ni2+ and adjacent Ni(0) is larger than that between Mg2+ and Ni (0), while Ni2+ situated deep inside MgO has weak interactions with surface Ni atoms. This work highlights the importance of subsurface Ni2+ in anchoring reduced surface Ni atom, which inhibits the aggregation of Ni particles and therefore, facilitates the growth of SWNTs with a narrow chirality distribution.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Optimisation of electrolytic solvents for simultaneous electrochemical
           exfoliation and functionalisation of graphene with metal nanostructures
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Andinet Ejigu, Benjamin Miller, Ian A. Kinloch, Robert A.W. Dryfe
      The development of a simple, simultaneous electrochemical exfoliation and functionalisation of graphene with metal nanostructures in a one-pot, single step process is reported. This approach is useful in terms of the reduction in processing time and cost, as well as aiding the control of the aggregation of graphene sheets. This first part of this work compares the efficiency of electrochemical graphite exfoliation in dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) and in a mixture of dimethyl carbonate (DMC) and ethylene carbonate (EC) in an electrolyte consisting of LiClO4 and tetraethylammonium tetrafluoroborate. In the second part, the best performing electrolytic solvent was used for in-situ functionalisation of graphene sheets with gold or cobalt nanostructures. The formation of solid layer electrolyte interface in the DMC/EC system is believed to stabilise the graphite from premature exfoliation and allowed the ions to intercalate efficiently to produce a relatively high yield of monolayer graphene sheets. By contrast, the electrochemical exfoliation of graphite in the other two solvents (DMSO and NMP) produced lower yields of few layer graphene. In particular, the co-intercalation of DMSO fragments the electrode by its decomposition by-products (sulfur/carbon oxides) before sufficient cation intercalation occurs. The simulations electrochemical exfoliation and functionalisation of graphene at a single applied potential in the presence of Au salt in DMC/EC solution resulted in the functionalisation of graphene sheets with a variety of high surface area Au nanowhiskers, nanodendrites, nanowires and lamellar nanoparticles. Alternatively, the use of Co(II) salt in the exfoliation solution resulted in the co-deposition of uniformly grown Co nanoparticles on graphene sheets. The metal-functionalised graphene sheets showed high catalytic activity and stability when used as an electrocatalyst for hydrogen evolution reactions. This process could be extended to other metal salts, or mixtures of metal salts, to form graphene-metal alloy composites for use in various applications.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Influence of chemical bonding on the variability of diamond-like carbon
           nanoscale adhesion
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Rodrigo A. Bernal, Polun Chen, J. David Schall, Judith A. Harrison, Yeau-Ren Jeng, Robert W. Carpick
      Diamond-like-carbon (DLC) is a promising material for tribological applications such as hard disk, automotive, machine tool, and aerospace coatings. We performed in-situ transmission electron microscopy (TEM) and molecular dynamics (MD) studies of nanoscale single-asperities made of tetrahedral amorphous carbon (ta-C, a type of DLC with high strength) contacting single-crystal diamond, to understand the factors controlling adhesion. Visualization of the contacts in TEM enabled us to correlate the asperity's geometry and the adhesion measurements. MD simulations allowed the atomic-scale mechanisms of adhesion to be elucidated and correlated with the TEM observations. Experimentally-determined pull-in forces show less scatter than pull-off forces. The magnitude of the pull-in forces is consistent with adhesion arising from van der Waals (VDW) interactions, allowing us to estimate the ta-C/diamond Hamaker constant. MD simulations with the AIREBO potential confirmed that including VDW interactions leads to less scatter in adhesive forces in approach than in separation. MD simulations with the REBO+S potential demonstrate that the large scatter in pull-off forces observed experimentally arises from the complex nature of covalent bonding between substrate and tip, influenced by the local energy landscape, hydrogen coverage, and the number of repeated contact events. The scatter in pull-off force also tends to decrease with increasing roughness.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • A flexible core-shell carbon layer MnO nanofiber thin film via host-guest
           interaction: Construction, characterization, and electrochemical
           performances
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Fan Wang, Chao Li, Jing Zhong, Zhenyu Yang
      Supermolecular complexation with cyclodextrins by non-covalent host-guest interaction is used for various applications. In this work, we fabricated the freestanding and flexible core-shell MnO/carbon nanofiber (CNF) composite thin films by host-guest interaction and high-voltage electrospining technique. The as-prepared composite thin film with dual carbon layer nanofibers showed smaller MnO particle size, lower electron-transfer resistance, and faster lithium ion migration, which were attributed to intermolecular non-covalent assembling behavior among polyacrylonitrile (PAN), β-cyclodextrin (β-CD) and Mn ion. As expected, the composite film as anode in Li-ion battery showed impressive performance: a high reversible capacity (∼1025 mAh g−1 at ∼0.1 A g−1), excellent rate capability (∼376 mAh g−1 at ∼5 A g−1), and superior cyclability (∼844 mAh g−1 at the current density of ∼1 A g−1 after 800 cycles). Such outstanding electrochemical performance endows the MCNFs composites with great potential as anode material for LIBs.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Electrochemical capacitive energy storage in PolyHIPE derived nitrogen
           enriched hierarchical porous carbon nanosheets
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Ashvini B. Deshmukh, Archana C. Nalawade, Indrapal Karbhal, Mohammed Shadbar Qureshi, Manjusha V. Shelke
      Porous and interconnected electrodes based on carbon nanoarchitectures offer comprehensive advantages of large specific surface area and high porosity consequently increasing the specific capacitance of ultracapacitor energy storage systems. Emulsion-templated polymers, PolyHIPEs (Polymerized High Internal Phase Emulsions) are highly porous polymers with a structure of cages interconnected by windows thus provide suitable framework to create such porous carbon nanostructures. Herein, nitrogen enriched porous carbon nanosheets are synthesized by pyrolysis of polymer-silica hybrid PolyHIPE and subsequent silica removal. This nitrogen enriched porous carbon nanosheets when tested as an electrode for ultracapacitor, showed specific capacitance as high as 209 F/g at a current density of 1 A/g in 1 M H2SO4with excellent capacity retention over long cycling.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Atomic and electronic structures of stable linear carbon chains on
           Ag-nanoparticles
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): D.W. Boukhvalov, I.S. Zhidkov, E.Z. Kurmaev, E. Fazio, S.O. Cholakh, L. D'Urso
      In this work, we report X-ray photoelectron (XPS) and valence band (VB) spectroscopy measurements of surfactant-free silver nanoparticles and silver/linear carbon chains (Ag@LCC) structures prepared by pulse laser ablation (PLA) in water. Our measurements demonstrate significant oxidation only on the surfaces of the silver nanoparticles with many covalent carbon-silver bonds but only negligible traces of carbon-oxygen bonds. Theoretical modeling also provides evidence of the formation of robust carbon-silver bonds between linear carbon chains and pure and partially oxidized silver surfaces. A comparison of theoretical and experimental electronic structures also provides evidence of the presence of non-oxidized linear carbon chains on silver surfaces. To evaluate the chemical stability, we investigated the energetics of the physical adsorption of oxidative species (water and oxygen) and found that this adsorption is much preferrable on oxidized or pristine silver surfaces than the adsorption of linear carbon chains, which makes the initial step in the oxidation of LCC energetically unfavorable.
      Graphical abstract image

      PubDate: 2017-12-27T01:41:47Z
       
  • Nitrogen-doped porous carbon with well-balanced charge conduction and
           electrocatalytic activity for dye-sensitized solar cells
    • Abstract: Publication date: March 2018
      Source:Carbon, Volume 128
      Author(s): Nan Xiao, Junwei Song, Yuwei Wang, Chang Liu, Ying Zhou, Zhiqiang Liu, Mingyu Li, Jieshan Qiu
      Nitrogen-doped porous carbon with well-balanced charge conduction and electrocatalytic activity were synthesized from nitrogen-rich pitch by hard-template method. The sample carbonized at 900 °C possessing high nitrogen content (7.11 wt.%) and large specific surface area exhibits high electrocatalytic activity in dye-sensitized solar cells. A fast charge conduction involving facile ion transport and rapid electron transfer can be attributed to the open framework structure and soft carbon nature of pitch derived porous carbon, respectively. Owing to these merits, the nitrogen-doped porous carbon delivers higher power conversion efficiency (8.75%) than that of the commercial Pt electrode (7.55%).

      PubDate: 2017-12-27T01:41:47Z
       
  • 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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      PubDate: 2017-12-13T07:15:05Z
       
  • 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
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 54.226.179.247
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2016