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  • Electrospun nitrogen-doped carbon nanofibers with tuned microstructure and enhanced lithium storage properties
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Chang Liu, Nan Xiao, Yuwei Wang, Ying Zhou, Gang Wang, Hongqiang Li, Yongqiang Ji, Jieshan Qiu

    Nitrogen-doped carbon materials hold great potential for high performance lithium storage. However, the excess defects introduced by dominated nitrogen doping methods may lead to a thickened solid electrolyte interphase (SEI), resulting in a higher Li+ diffusion resistance and inferior rate performance. Herein, we report the fabrication of carbon nanofibers (CNFs) by co-electrospinning the mixture of nitrogen-rich pitch, a soft carbon precursor, with polyacrylonitrile (PAN) in controlled mass ratio to make composite CNFs with tuned microstructure and relatively high nitrogen content. The result shows that the SEI formed on the composite CNFs with less surface defects is much thinner yet tighter than that formed on the PAN-based CNFs. As such, the composite CNFs present a doubled capacity retention of 37.1% to that of the PAN-based CNFs at 10 A g−1. More importantly, the cycle retention of the composite CNFs anode is 88% after 1000 cycles at 2 A g−1, much higher than that of PAN-based CNFs (61.5%). It is believed that the improved rate and cycle performance are due to the superior structure and chemical composition of the SEI, which can be attributed to the modified microstructure by addition of nitrogen-rich pitch to a great extent.

    更新日期:2018-07-18
  • Influence of sonication conditions and wrapping type on yield and fluorescent quality of noncovalently functionalized single-walled carbon nanotubes
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Nathaniel Kallmyer, Trinh Huynh, Joseph Connor Graves, Joseph Musielewicz, Denis Tamiev, Nigel Reuel

    As nanomaterials have become more accessible, nanoscale biosensor research has expanded to many useful applications. One such nanomaterial is the single-walled carbon nanotube (SWCNT), which fluoresces in the near-infrared biological window, making it ideal for in vivo applications. SWCNT can be suspended in water when non-covalently functionalized with an amphiphilic polymer or surfactant (e.g. ‘wrapped’); the suspended SWCNT can act as a simple optical probe or as a sensor by engineering the wrapping to have selective domains. The process of suspending nanotubes is typically achieved by sonication. While much application-focused research has been performed on SWCNT sensors and probes, little has been done to understand factors affecting SWCNT fluorescent quality after suspension. We explored effects of sonication power and duration on an array of nine potential wrappings including proteins, DNA, oligosaccharides, polysaccharides, synthetic polymers, and surfactant solutions. Optimal sonication conditions were found to vary on an individual wrapping basis. These trends may be used to predict optimal processing conditions to suspend SWCNT with maximal start fluorescence for various wrappings, improving dynamic range and sensitivity. These results also point to the need for control of sonication conditions in large scale synthesis to ensure tighter batch-to-batch reproducibility of nanotube sensors.

    更新日期:2018-07-18
  • A simple means of producing highly transparent graphene on sapphire using chemical vapor deposition on a copper catalyst
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Gloria Anemone, Esteban Climent-Pascual, Amjad Al Taleb, Hak Ki Yu, Felix Jiménez-Villacorta, Carlos Prieto, Alec M. Wodtke, Alicia De Andrés, Daniel Farías

    Chemical vapor deposition (CVD) is one of the best ways to scalably grow low cost, high quality graphene on metal substrates; unfortunately, it not ideal for producing graphene on dielectric substrates. Here, we demontrate production of a high quality graphene layer on Sapphire using CVD with a copper catalyst. The catalyst consists of a thin copper film grown epitaxially on α- Al 2 O 3 (0001). After CVD growth of Graphene, the copper can be removed by simple evaporation in the presence of a carbon source ( C 2 H 4 ). We characterized the resulting graphene layer using Raman spectroscopy, atomic force microscopy (AFM), optical transmission and helium atom scattering (HAS). The sample exhibited a reduced Raman D peak and an excellent 2D to G ratio. AFM and HAS show large graphene domains over a macroscopic region. We measured > 86 % transparency over the visible spectrum.

    更新日期:2018-07-18
  • Multilayered graphene grafted copper wires
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Lee-Woon Jang, Luman Zhang, Mariela Menghini, Hyunjin Cho, Jun Yeon Hwang, Dong Ick Son, Jean-Pierre Locquet, JinWon Seo

    Multilayered graphene is grown on copper (Cu) wires by chemical vapor deposition. Mechanical, chemical, thermal and electrical performances are investigated as a function of growth conditions. The graphene layer which makes a volume of approximately 0.02% of the Cu wire enables a 28–37% improvement on tensile strength and strain-to-failure. The chemical resistance of graphene grafted Cu wires increases by 1.5–3 times in nitric acid, aqua regia, and 1M ammonium persulfate etchants. The electrical resistivity of graphene grafted Cu wires shows almost constant values with increasing temperature up to 175 °C, while the resistivity degradation of Cu wires without graphene starts to increase from 70 °C. We demonstrate that graphene can protect the Cu wire from thermal oxidation and chemical etchants and can effectively enhance the mechanical and electrical properties of the Cu wire.

    更新日期:2018-07-18
  • Cobalt encapsulated in the nitrogen and sulfur co-doped carbon nanotube supported platinum for the oxygen reduction reaction catalyst
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Tae-Hyun Kim, Chi-Young Jung, Ranjith Bose, Sung-Chul Yi

    In this paper, cobalt encapsulated in nitrogen and sulfur co-doped carbon nanotube (Co-NST) was synthesized through a simple pyrolysis method to impregnate platinum (Pt) nanoparticles. The Co-NST presented a bamboo-like morphology with the high degree of graphitization. Owing to the dual heteroatoms co-doped in the carbon matrix, the Pt supported on the Co-NST (Pt/Co-NST) showed the well-dispersed morphology of the Pt nanoparticles. In addition, the synergistic effect between the Co-NST support and the Pt nanoparticle was observed from the physicochemical characterizations. As a result, the Pt/Co-NST presented improved oxygen reduction reaction (ORR) activity and stability compared to the commercial Pt/C. The mass activity and specific activity of the Pt/Co-NST presented 508.48 mA mgPt−1 and 723.93 μA cmPt−2, respectively, which exhibited more than 3 times higher compared to those of the commercial Pt/C. After repeating 5000 potential cycles, the Pt/Co-NST showed improved stability with 29 mV loss in half-wave potential, while the half-wave potential of the commercial Pt/C was severely decreased by 118 mV.

    更新日期:2018-07-18
  • Novel timed and self-resistive heating shape memory polymer hybrid for large area and energy efficient application
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Manuela Loeblein, Asaf Bolker, Zhi Lin Ngoh, Lanxin Li, Eliana Wallach, Siu Hon Tsang, Matthieu Pawlik, Ronen Verker, Nurit Atar, Irina Gouzman, Edwin Hang Tong Teo

    Shape memory polymers (SMPs) are a polymeric smart material that can register two or more temporary shapes and transform to one another through an external stimulus. Despite their compactness and customizability, SMPs haven't been able to be adopted for mainstream applications. Since the majority of SMPs are triggered by heat, and SMPs have a very poor thermal conductivity, large thermal gradients within the polymer appear which cause slow response, inhomogeneous heat distribution and thus non-uniform transformation of shapes and cracks. Many have attempted to improve their thermal performance through the incorporation of filler-based nanomaterials. However, the outcome is ineffective as the spatial dispersion of fillers within the SMP is inhomogeneous and leads to performance loss. Contrastingly, the herein presented new class of nanocomposite-SMP, composed by 3D-foam fillers, showcase a much more efficient SMP adaptable to larger area with faster transformation speed and without any performance loss. Furthermore, the improved thermal properties lead to a decrease in required input energy, as well as render the SMP a self-heating capability which can be further designed into timed multi-step SMP behavior.

    更新日期:2018-07-18
  • Tuning micro-wrinkled graphene films for stretchable conductors of controllable electrical conductivity
    Carbon (IF 7.082) Pub Date : 2018-07-17
    Chunfang Feng, Zhifeng Yi, Ludovic F. Dumée, Fenghua She, Zheng Peng, Weimin Gao, Lingxue Kong

    Accurately controlling the electrical conductivity of wrinkled graphene or graphene oxide (GO) structures is challenging due to the complex sheet-to-sheet interactions and hierarchical interactions at the nanoscale. In this paper, wrinkled GO films with predictable electrical conductivty by precisely controlling thickness ranging from 0.69 to 1.68 μm were fabricated with a thermal process where a GO-coated polystyrene shrink film was isotropically shrunk. Theoretical and experimental results show consistent dependence of the wrinkle wavelength on the GO film thickness. Beyond a certain thcikness threshold, poorly wrinkled structures were formed as GO sheets started delaminating from the shrink films. A coarse-grain molecule model based on molecular dynamic simulation principles was developed to understand the formation of the wrinkles, and establish a relationship between GO thickness and the wrinkle wavelength generated. The electrical resistance was found to decrease when the thickness of the GO films increases. The formed composite film can maintain a stable electrical conductivity after experiencing up to 1000 stretching-release cycles under 10% strain. With controllable eletrical conductivity, the reported composites can offer potential applications as a strain sensor with tuneable sensing range and high duribility.

    更新日期:2018-07-18
  • Low percolation threshold in highly conducting graphene nanoplatelets/glass composite coatings
    Carbon (IF 7.082) Pub Date : 2018-07-12
    A. Nistal, E. Garcia, D. Pérez -Coll, C. Prieto, M. Belmonte, M.I. Osendi, P. Miranzo

    Thermal sprayed thick glass coatings with a small percentage of multilayer graphene nanoplatelets (GNP) demonstrate electrical functionality with a quite remarkable low percolation limit (1.18 vol.%). This low critical content and the high electrical conductivity (∼40 S m−1) observed for the in-plane direction are related to the peculiar coating microstructure, formed by the pileup of lamellar amorphous particles decorated by GNP mostly following a surface parallel orientation. The general effective media model fitting to the electrical conductivity data for these coatings suggests a 3D connectivity of graphene and estimates an upper limit conductivity for the GNP of 105 S m−1. Hall Effect shows the n-type behavior intrinsic to the SiO2/graphene interface, and carrier density and mobility rising with the GNP content. In addition, the coatings evidence a very high solar absorptivity that jointly with their high electrical conductivity broadens their potential applications, among others, for electromagnetic interference shielding or as photothermal detector and solar absorber for solar steam generation and water desalination.

    更新日期:2018-07-14
  • Multi-channel FeP@C octahedra anchored on reduced graphene oxide nanosheet with efficient performance for lithium-ion batteries
    Carbon (IF 7.082) Pub Date : 2018-07-12
    Peipei Zhu, Ze Zhang, Shiji Hao, Bowei Zhang, Pengfei Zhao, Ji Yu, Jianxin Cai, Yizhong Huang, Zhenyu Yang

    Iron phosphide (FeP) is a promising anode material for Li-ion batteries (LIBs) due to its low cost and high theoretical capacity. To design FeP anode materials with multi-channels for both ions and electrons will greatly help to realize fast ion and electron diffusion and high-rate capability of LIBs, and effectively overcome its intrinsic shortcomings of low conductivity and large volume expansion. Herein, a novel octahedral multi-channel FeP@C/rGO composite has been fabricated by a simple solvothermal process followed by carbonization and phosphorization. The as-prepared FeP@C/rGO composite displays an excellent rate capacity (497 mAh g−1 at 5 A g−1), as well as a high reversible capacity (1080 mAh g−1 at 0.1 A g−1) and superior cyclability with a capacity decay rate of 0.04% per cycle upon 500 cycles. The outstanding electrochemical performance of FeP@C/rGO composite can be attributed to the unique stable carbon octahedral multi-channel frameworks and N/P co-doping interconnect graphene conductive network, which significantly facilitate the Li-ion and electron transfer and accommodate the large volume change during cycling. This work shows a feasible strategy to fabricate FeP-based composites with multi-channels structure as a high-performance anode for lithium-ion batteries.

    更新日期:2018-07-14
  • Gate-enhanced exciton-phonon coupling in photocurrent of (6,5) single-walled carbon nanotube based visible sensing field effect transistor
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Ki Hong Park, Seung-Hoon Lee, Fumiyuki Toshimitsu, Jihoon Lee, Sung Heum Park, Fujikaya Tsuyohiko, Jae-Won Jang

    A visible sensing field effect transistor (FET) with a channel length of 100 nm for individual (6,5) single-walled carbon nanotubes (SWCNTs) is fabricated via a selective sorting method using 9,9-dioctyfluorenyl-2,7-diyl–bipyridine (PFO–BPy) polymer. The FET of the (6,5) SWCNTs shows p-type behavior with hundreds of on-off ratios and on-state conductivity of 50 ± 4.0 (Ω m)−1. In addition, the photocurrent of the FET of the (6,5) SWCNTs in the visible range increases (maximum 200 times at 620 nm) with higher gate voltage. E22 transition and PFO-BPy transition are observed in the FET of the (6,5) SWCNTs without application of a gate voltage. Interestingly, exciton-phonon coupled E22 transition due to gate-doping (p-type), which has been reported in photoluminescence and absorption studies, is expected to occur in the photocurrent of the FET at negatively higher gate voltage (≤−4 V). In addition, the exciton-phonon coupled E22 transition is prominently observable when carrier concentration by gate doping becomes approximately two-hundred sixty times (260 ± 43) larger than carrier concentration without application of a gate voltage. This demonstration would be useful for the development of SWCNT-based visible sensors with gate control in the SWCNT devices.

    更新日期:2018-07-12
  • Enhanced mechanical properties of aluminum based composites reinforced by chemically oxidized carbon nanotubes
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Baisong Guo, Xinming Zhang, Xi Cen, Biao Chen, Xinhua Wang, Min Song, Song Ni, Jianhong Yi, Tao Shen, Yong Du

    Uniform dispersion and suitable interface are two critical issues to realize the high strengthening potential of carbon nanotubes (CNTs) in metal based composites. In this work, surface modification of CNTs was applied to simultaneously overcome these two challenges in Al matrix composites by a chemical oxidization method. It was found that the functional groups, such as hydroxyl and carboxyl groups, can be successfully decorated on the surface of CNTs by chemical oxidization, thus improving the dispersion of CNTs in ethanol. Concurrently, the morphology of oxidized CNTs and the Al-CNTs interface depend strongly on the activity of the applied oxidants. The mixture of sulphuric acid and hydrogen peroxide can slightly etch the outer walls of CNTs, which benefits the anchoring bonding between the CNTs inner walls and Al matrix, and improves the interface stability, hence exploits the load bearing capacity of the CNTs inner walls and eventually leads to the effective load transfer between Al and CNTs. The outstanding reinforcing effect of surface-modified CNTs was investigated and discussed by the strengthening models. This work provides a new approach to uniformly disperse CNTs and improve interfacial bonding for CNTs reinforced composites simultaneously.

    更新日期:2018-07-12
  • Hidden by graphene – Towards effective screening of interface van der Waals interactions via monolayer coating
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Alberto Ambrosetti, Pier Luigi Silvestrelli

    Recent atomic force microscopy (AFM) experiments [ACS Nano 2014, 8, 12410–12417] conducted on graphene-coated SiO2 demonstrated that monolayer graphene (G) can effectively screen dispersion van der Waals (vdW) interactions deriving from the underlying substrate: despite the single-atom thickness of G, the AFM tip was almost insensitive to SiO2, and the tip-substrate attraction was essentially determined only by G. This G vdW opacity has far reaching implications, encompassing stabilization of multilayer heterostructures, micromechanical phenomena or even heterogeneous catalysis. Yet, detailed experimental control and high-end applications of this phenomenon await sound physical understanding of the underlying physical mechanism. By quantum many-body analysis and ab-initio Density Functional Theory, here we address this challenge providing theoretical rationalization of the observed G vdW opacity for weakly interacting substrates. The non-local density response and ultra slow decay of the G vdW interaction ensure compensation between standard attractive terms and many-body repulsive contributions, enabling vdW opacity over a broad range of adsorption distances. vdW opacity appears most efficient in the low frequency limit and extends beyond London dispersion including electrostatic Debye forces. By virtue of combined theoretical/experimental validation, G hence emerges as a promising ultrathin shield for modulation and switching of vdW interactions at interfaces and complex nanoscale devices.

    更新日期:2018-07-12
  • Ultrathin-graphite foam with high mechanical resilience and electroconductibility fabricated through morphology-controlled solid-state pyrolysis of polyaniline foam
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Hua Xiao, Pu Xie, Shou Ji Qiu, Min Zhi Rong, Ming Qiu Zhang

    Three-dimensional carbon-based foam (3D-CF) possesses many fascinating properties such as giant conductivity, high thermal insulation, outstanding mechanical performance, and excellent chemical and thermal stabilities. However, most 3D-CFs acquired by the previously reported fabrication methods have some limitations, such as uncontrollable morphology, plenty of inherent defects, difficult to realize self-standing after removing sacrificial template, and overlapping joint flaws among graphene layers. Although significant research efforts have been devoted to develop 3D foam, it is still a challenging task to obtain 3D-CF with both high conductivity and outstanding mechanical performance, simultaneously. To address this issue, a novel and easy fabricating approach for 3D ultrathin-graphite carbon foam (3D-UGF) was explored by a morphology-retaining pyrolysis of polyaniline foam precursors. The typical 3D-UGF graphitized at 2800 °C exhibited stronger compressive strength and electrical conductivity under the compressive strain of 90%, and remained constant even after 2000 cycles, which are comparable to the previously reported state-of-the-art 3D-CF foam with the same density. Cycling performance of the lithium-sulfur and lithium-air batteries with the 3D-UGF as binder-free cathode is as high as 1590 mAh g−1 and 920 mAh g−1 after deep discharge/charge 100 cycles, respectively.

    更新日期:2018-07-12
  • Multi-Walled Carbon Nanotube-Coated Spiral Coils for Loss Reduction in Wireless Power Transfer Systems
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Kamran Keramatnejad, Dawei Li, Hossein Rabiee Golgir, Loic Constantin, Xi Huang, Qiming Zou, Jean-Francois Silvain, Stephen Ducharme, Yongfeng Lu

    Realization of high efficiency and long transmission range in high-frequency wireless power transfer (WPT) systems has always been hindered by the increased resistance due to the eddy current loss occurring in the inductive coils. In this study, multi-walled carbon nanotube-coated copper (MWCNT-Cu) coils are successfully introduced to address this limitation by implementing the frequency-inert MWCNT channels along with using their high-surface areas to realize the electromagnetic shielding of the Cu substrate through multiple reflection mechanisms. At a frequency of 15 MHz, the resistance of the individual MWCNT-Cu coil was reduced to less than 40% of its original value for primitive Cu, leading to more than a four-fold increase in their quality factor. When MWCNT-Cu coils were used as the transmitting component, the transmission efficiency of the WPT system increased from 10.57% to 95.81% at a transmission distance of 4 cm and a frequency of 3.45 MHz. Finally, it was demonstrated that the loss reduction improved as the eddy current loss became more severe in coils with higher inductance values, which makes this approach promising for significantly improving the performance of inductive components in WPT applications.

    更新日期:2018-07-12
  • Z-scheme reduced graphene oxide/TiO2-Bronze/W18O49 ternary heterostructure towards efficient full solar-spectrum photocatalysis
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Changchao Jia, Xiao Zhang, Katarzyna Matras-Postolek, Baibiao Huang, Ping Yang

    Z-scheme reduced graphene oxide (rGO)/TiO2-bronze (TiO2-B)/W18O49 photocatalyst consisted of rGO, super-thin TiO2-B nanosheets, and W18O49 nanofibers was fabricated by a two-step solvothermal synthesis route. The TiO2-B nanosheets were tightly attached on rGO firstly. W18O49 nanowires were then grown on rGO/TiO2-B. Precursors and reaction conditions play important roles for getting the optimal microstructure. The ternary photocatalyst is able to absorb sunlight ranging from ultraviolet to near infrared regions, which makes full use of light for efficiently photocatalytic degrading organic pollutants. The light absorption intensity and photon-generated carrier transfer efficiency are both improved with adding rGO. The localized surface plasmon resonance effect arose from the nonstoichiometric W18O49 is in favour of the absorption range of the rGO/TiO2-B/W18O49 composite broadening to near infrared light range. The photocatalytic mechanism of Z-scheme rGO/TiO2-B/W18O49 composite was verified by an electron spin resonance test. The conduction band of TiO2-B and the valence band of W18O49 are used in the photocatalytic degradation of rhodamine B, facilitating the efficient separation of photogenerated carriers. The rGO/TiO2-B/W18O49 heterostructure exhibits an excellent photocatalytic performance under full solar-spectrum irradiation. The result may represent a new strategy for the construction of nanocomposites with suitable band structure in the efficient application of full solar light.

    更新日期:2018-07-12
  • Tuning hydroxyl groups for quality carbon fiber of lignin
    Carbon (IF 7.082) Pub Date : 2018-07-11
    Qiang Li, Mandar T. Naik, Hao-Sheng Lin, Cheng Hu, Wilson K. Serem, Li Liu, Pravat Karki, Fujie Zhou, Joshua S. Yuan

    Lignin-based carbon fiber is struggling to apply into industry, due to its low mechanical performance. Our concept is that lignin chemical features impact its interactions with guest molecules and crystallite formation in carbonization, and thus carbon fiber mechanical performance. We recently demonstrated that fractionating lignin polymers according to their molecular weight enhanced the elastic modulus, but the process used costly enzyme and dialysis tubes and difficult to scale up. Here we present a simple one-pot lignin processing technology that only precipitate lignin into aqueous acid. Our approach is based on manipulating lignin hydroxyl groups, which improves multiple hydrogen bonding and linear chemical linkages to enhance molecular interactions and thereby carbon fiber crystallite structures. Carbon fiber out of the presented technique has elastic modulus comparable with that derived from the costly enzymatic and dialysis fractionation methods, and even the traditional PAN-based carbon fibers. The presented technology offered a route to make quality lignin-based biorenewable carbon fiber by regulating fiber precursor at molecular level, which has a broad application in upgrading industrial lignin waste of paper-making industry and lignocellulosic biorefinery.

    更新日期:2018-07-12
  • Hybrid spray-coating, laser-scribing and ink-dispensing of graphene sensors/arrays with tunable piezoresistivity for in situ monitoring of composites
    Carbon (IF 7.082) Pub Date : 2018-07-09
    Sida Luo, Yong Wang, Guantao Wang, Fu Liu, Yujiang Zhai, Yun Luo

    Graphene based nanotechnology has offered a variety of novel strategies for enabling self-sensing and diagnosing functionalities for next-generation composites. In comparison to traditional methods with complicated procedures and limited scalability, a new process is impending for graphene sensor fabrication with designable shape and controllable performance. Toward this goal, this paper combined multiple computer-aided processes for designing graphene thin film sensors and arrays on composites, including spray-coating, laser-scribing and ink-dispensing. The processing-structure-property relationship was systematically investigated for understanding the piezoresistive performance of the laser scribed graphene (LSG) sensors. It is determined that by increasing the cycle time of laser irradiation, the gauge factor could be tailored up to 3 orders of magnitude from ∼450 to ∼0.6. The accumulated bump-shaped structure originated from the more intense process of graphene oxide (GO) reduction is believed to disrupt the efficiency of load-transfer and degrade the resulting performance. With the optimized recipe, versatility of the LSG sensors and arrays deployed with ink-printed circuits were further explored for monitoring and mapping large-scale deformation and strain distribution of polymeric composites.

    更新日期:2018-07-09
  • Pinhole evolution of few-layer graphene during electron tunneling and electron transport
    Carbon (IF 7.082) Pub Date : 2018-07-09
    Shuai Tang, Yu Zhang, Ningsheng Xu, Peng Zhao, Runze Zhan, Juncong She, Jun Chen, Shaozhi Deng

    With graphene as a well-known representative, two-dimensional (2D) atomic crystals are single-layer or few-layer crystalline materials. It is significant to investigate the structure evolution of the 2D atomic crystals in electronic movement process, because it relates to the stability of material properties and the feasibility of the device application. Here, the pinhole evolution of few-layer graphene during electron tunneling and electron transport was observed using in situ transmission electron microscopy (TEM). For few-layer graphene with defects, pinholes expanded with an increase on the electron tunneling current and time, respectively. However, during electron transport processes, with increasing current and time, both, expansion and shrinkage behaviors could be observed among the pinholes distributed within the graphene nanosheet. These behaviors are the result of competition between sublimation and self-repair. Both types of pinhole evolution aim to form a smooth surface with lower surface free energy. The critical boundary conditions for the sublimation and self-repair are determined by the temperature, graphene pinhole structure and active graphene fragment. These findings provide significant reference for the stability of graphene structure and the reliability of graphene based electronic device.

    更新日期:2018-07-09
  • 19-Fold thermal conductivity increase of carbon nanotube bundles toward high-end thermal design applications
    Carbon (IF 7.082) Pub Date : 2018-07-05
    Yangsu Xie, Tianyu Wang, Bowen Zhu, Chaoyi Yan, Peixin Zhang, Xinwei Wang, Gyula Eres

    In high temperature annealing of carbon nanotube (CNTs) bundles for structure and thermal conductivity (κ) improvement, the statistical errors from sample-wide structure variation and sample transfer/preparation significantly overshadows the understanding of structure-κ correlation and change. In this work, the sequential process of current-induced thermal annealing (CITA) on improving the structure, electrical and thermal conductivities of chemical vapor deposition grown CNT bundles is studied for the first time. Our in-situ κ measurement using the transient electro-thermal technique uncovers the conjugated dynamic electrical, thermal, and structural properties. The electrical resistance and thermal diffusivity evolution of CNT bundles during CITA is studied. The thermal diffusivity and κ before and after CITA are measured from room temperature down to 10 K to uncover the reduction of defect density and enhancement of inter-tube connection strength after CITA. Our micro-Raman spectroscopy study from the most annealed region to the non-annealed region reveals significantly improved order in sp2 bonding carbon structure and reduced defects along the sample length. The resulting κ has 5–19 times increase at the most annealed region of CNT bundles. The intrinsic κ of CNT walls against the annealing temperature is also determined, which reaches a level as high as 754 W/m·K after CITA.

    更新日期:2018-07-08
  • Thermal conductivity enhancement of reduced Graphene oxide via chemical defect healing for efficient heat dissipation
    Carbon (IF 7.082) Pub Date : 2018-07-05
    Chae Bin Kim, Janggeon Lee, Jaehyun Cho, Munju Goh

    As next-generation miniaturized electronics are being developed with higher power density, a need for effectively dissipating the generated heat during the device operation is becoming ever greater. Nano carbons such as graphene are strong candidates for heat dissipating materials with lightweights owing to their low densities with extraordinary thermal properties rooted from their highly crystalline and conjugated structures. Starting from a relatively less ordered, cheaper, and mass producible graphene oxide (GO), to this end, we herein describe a sequential chemical transformation to obtain a higher ordered crystalline and conjugated structure of the GO. A conventional reduction followed by a chemical defect healing process via intramolecular cross-dehydrogenative coupling gradually increased graphitic and crystalline structures of the GO as evidenced by a variety of spectroscopic and microscopic experiments. Consequently, the thermal conductivity of the final product was enhanced to 9.90 W/mK, corresponding to over 500% of the starting GO (1.92 W/mK). Moreover, the defect healed GO itself was successfully used as a heat dissipating material, quickly lowering its temperature by ∼36 °C during a continuous heating at 100 °C. Finally, we also demonstrated the defect healed GO as filler to enhance the thermal conductivity of the polymeric composites.

    更新日期:2018-07-08
  • Tuning surface chemistry and morphology of graphene oxide by γ-ray irradiation for improved performance of perovskite photovoltaics
    Carbon (IF 7.082) Pub Date : 2018-07-06
    Jae Sang Cho, Woongsik Jang, Sung Cik Mun, Minji Yi, Jong Hyeok Park, Dong Hwan Wang

    We demonstrated a simple and effective modification of graphene oxide (GO) to enhance the device performance of perovskite photovoltaics. The surface chemistry and morphology of GO was tailored by irradiating aqueous GO solution with 60Co γ-ray. During the irradiation, hydroxyl radicals were believed to be released from water radiolysis and oxidized the surface of pristine GO sheets, supposedly. Furthermore, large GO agglomerates scattered as individual GO sheets with small lateral dimensions, which is advantageous to uniform distribution of GO sheets in PEDOT:PSS layer. PEDOT:PSS layer with γ-ray irradiated GO (γ-GO) facilitated efficient hole transport properties in perovskite solar cells. PEDOT:PSS layer became more hydrophobic by embedding γ-GO after thermal annealing and thus improved the crystallinity of perovskite layer on top of the PEDOT:PSS. Consequently, embedding γ-GO in PEDOT:PSS layer resulted in better electrical properties than PEDOT:PSS layer without GO or with pristine GO. As a result, power conversion efficiency was improved owing to increased charge generation/extraction, and photoluminescence in the perovskite photoactive layer.

    更新日期:2018-07-08
  • Raman resonance profile of an individual confined long linear carbon chain
    Carbon (IF 7.082) Pub Date : 2018-07-06
    Sebastian Heeg, Lei Shi, Thomas Pichler, Lukas Novotny

    This paper reports tip-enhanced, polarization dependent and excitation energy dependent Raman measurements of an individual long linear carbon chain confined in a double-walled carbon nanotube. We determine the band gap of the chain (2.093 eV) from a Raman resonance profile with a line width Γ=145meV, which corresponds to a lifetime of τ=4.5fs for the excited state of the chain. In the absence of external perturbations, this suggests that the chain's excited state dynamics depend on the confinement inside the nanotube and therefore on the chirality of the encasing carbon nanotube.

    更新日期:2018-07-08
  • Efficient defect healing and ultralow sheet resistance of laser-assisted reduced graphene oxide at ambient conditions
    Carbon (IF 7.082) Pub Date : 2018-07-07
    Aspasia Antonelou, Labrini Sygellou, Katerina Vrettos, Vasilios Georgakilas, Spyros N. Yannopoulos

    Reduction of graphene oxide (GO) to a low-resistance product is one of the most versatile routes to obtain large volume graphene-based materials. A number of chemical and thermal methods are being applied to achieve this goal, albeit each one is bound to certain disadvantages and limitations. Laser-assisted reduction has emerged as a promising method apt to overcome issues related to chemical and thermal reduction. Despite that a large number of efforts have been focused on laser-induced reduction of GO, its transformation to high quality reduced GO still remains a bottleneck. Here, it is shown that low-cost, millisecond lasers, widely used in the welding industry, achieve excellent reduction of GO to a product with the lowest sheet resistance yet reported by any laser-assisted method. For comparison, GO is reduced by chemical and thermal methods. Raman and x-ray photoelectron spectroscopies are applied to investigate the underlying structural changes providing evidence for the removal of oxygen-containing species and defect healing. Operation at ambient conditions, single pulse irradiation and a 2.60 mm wide focusing spot, demonstrate the high potential of this approach to the scalability of the reduction process towards producing large volumes of high-quality reduced graphene oxide at low cost.

    更新日期:2018-07-08
  • Pt nanocrystals grown on three-dimensional architectures made from graphene and MoS2 nanosheets: Highly efficient multifunctional electrocatalysts toward hydrogen evolution and methanol oxidation reactions
    Carbon (IF 7.082) Pub Date : 2018-07-04
    Zhiqiang Gao, Miaomiao Li, Jiayu Wang, Jixin Zhu, Xianmin Zhao, Huajie Huang, Jianfeng Zhang, Yuping Wu, Yongsheng Fu, Xin Wang

    Although electrocatalytic hydrogen evolution and methanol oxidation have long been regarded as promising technologies for future energy production and conversion, the incapability of the electrode catalysts poses a major impediment to their large-scale commercialization. Herein, we present a facile co-assembly approach to the fabrication of Pt nanocrystals grown on 3D architectures built from ultrathin graphene and MoS2 nanosheets. By virtue of their unique textural features, such as large specific surface area, 3D cross-linked porous framework, homogeneous distribution of Pt nanoparticles, and excellent electron conductivity, the resulting Pt/graphene-MoS2 architectures possess multifunctional catalytic activities toward hydrogen evolution and methanol oxidation reactions, accompanied by high durability and strong poison tolerance, which significantly outperform those for conventional Pt/carbon black, Pt/graphene, and Pt/MoS2 catalysts. It is believed that such a simple bottom-up design concept can open up new possibilities for the up-scale synthesis of various 3D hybrid architectures with metals or metal oxides for energy-related applications.

    更新日期:2018-07-05
  • An effective in situ reduction strategy assisted by supercritical fluids for the preparation of graphene -polymer composites
    Carbon (IF 7.082) Pub Date : 2018-07-03
    Suchithra Padmajan Sasikala, Wilfrid Neri, Philippe Poulin, Cyril Aymonier

    The chemical/thermal in situ reduction of graphene oxide (GO) in GO-polymer composite is consistently challenged by the presence of undesirable chemical residues/temperature degradation restriction of the polymer. In order to tackle this problem, we prepared graphene oxide-polyvinyl alcohol (GO-PVA) composite films by simple solution casting method. An effective in situ supercritical fluid reduction strategy comprising of supercritical CO2 and ethanol binary system under N2 atmosphere was developed by stepwise comparison of different reduction methods. The resulting rGO-PVA composite films comprising of 10 wt% rGO showed an electrical conductivity of (51.7 S/m) and Young's modulus of 3.1 GPa. Different weight loadings of GO in the polymer composite films were found to affect the electrical and mechanical properties of the resulting rGO-polymer films. The in situ supercritical fluid reduction strategy was demonstrated further for successfully obtaining rGO-polyethylene glycol films (rGO-PEG) and rGO-PVA fiber.

    更新日期:2018-07-04
  • Flexible pressure sensors using highly-oriented and free-standing carbon nanotube sheets
    Carbon (IF 7.082) Pub Date : 2018-07-02
    Sungwoo Chun, Wonkyeong Son, Changsoon Choi
    更新日期:2018-07-02
  • Multifunctional fluorescent “Off-On-Off” nanosensor for Au3+ and S2− employing N-S co-doped carbon–dots
    Carbon (IF 7.082) Pub Date : 2018-07-02
    Vinay Sharma, Navpreet Kaur, Pranav Tiwari, Anoop K. Saini, Shaikh M. Mobin
    更新日期:2018-07-02
  • Charge-transfer mediated nanopore-controlled pyrene derivatives/graphene colloids
    Carbon (IF 7.082) Pub Date : 2018-07-02
    Austina D. Putri, Nurul Chotimah, Sanjeev Kumar Ujjain, Shuwen Wang, Ryusuke Futamura, Fernando Vallejos-Burgos, Fitri Khoerunnisa, Masafumi Morimoto, Zhipeng Wang, Yoshiyuki Hattori, Toshio Sakai, Katsumi Kaneko
    更新日期:2018-07-02
  • Scaling of binding affinities and cooperativities of surfactants on carbon nanotubes
    Carbon (IF 7.082) Pub Date : 2018-07-02
    Minsuk Park, Junmo Park, Jiyun Lee, Sang-Yong Ju
    更新日期:2018-07-02
  • A novel approach to strengthen naturally pored wood for highly efficient photodegradation
    Carbon (IF 7.082) Pub Date : 2018-06-30
    Hui Mei, Weizhao Huang, Chengxu Hua, Yawei Xu, Laifei Cheng
    更新日期:2018-07-01
  • 更新日期:2018-07-01
  • Formation of hollow carbon nanoshells from thiol stabilised silver nanoparticles via heat treatment
    Carbon (IF 7.082) Pub Date : 2018-06-30
    Julie A. Watts, Mike W. Fay, Graham A. Rance, Paul D. Brown, Andrei N. Khlobystov
    更新日期:2018-07-01
  • Extremely large, non-oxidized graphene flakes based on spontaneous solvent insertion into graphite intercalation compound
    Carbon (IF 7.082) Pub Date : 2018-06-30
    Jungmo Kim, Gabin Yoon, Jin Kim, Hyewon Yoon, Jinwook Baek, Joong Hee Lee, Kisuk Kang, Seokwoo Jeon
    更新日期:2018-07-01
  • 更新日期:2018-07-01
  • Operation optimization of ultra-high-temperature furnace using graphite heater
    Carbon (IF 7.082) Pub Date : 2018-06-28
    Masaki Okada, Tomoyuki Okuni, Michio Inagaki
    更新日期:2018-06-30
  • Oxidation of carbon by gaseous metal oxide: A multi-path mechanism study
    Carbon (IF 7.082) Pub Date : 2018-06-28
    Quan Zhang, Minhua Zhang, Tomasz Wiltowski
    更新日期:2018-06-30
  • Semi-transparent biomass-derived macroscopic carbon grids for efficient and tunable electromagnetic shielding
    Carbon (IF 7.082) Pub Date : 2018-06-29
    Zeping Chen, Da Yi, Bin Shen, Lihua Zhang, Xiaohui Ma, Yongyan Pang, Li Liu, Xingchang Wei, Wenge Zheng
    更新日期:2018-06-30
  • Modal analysis for determining the size-and temperature-dependent bending rigidity of graphene
    Carbon (IF 7.082) Pub Date : 2018-06-29
    Banafsheh Sajadi, Simon van Hemert, Behrouz Arash, Pierpaolo Belardinelli, Peter G. Steeneken, Farbod Alijani
    更新日期:2018-06-30
  • Nanoscale infrared identification and mapping of chemical functional groups on graphene
    Carbon (IF 7.082) Pub Date : 2018-06-29
    Cian Bartlam, Suzanne Morsch, Kane W.J. Heard, Peter Quayle, Stephen G. Yeates, Aravind Vijayaraghavan
    更新日期:2018-06-30
  • 更新日期:2018-06-30
  • Mechanochemical synthesis of porous carbon at room temperature with a highly-ordered sp2 microstructure
    Carbon (IF 7.082) Pub Date : 2018-06-29
    M.E. Casco, F. Badaczewski, S. Grätz, A. Tolosa, V. Presser, B. Smarsly, L. Borchardt
    更新日期:2018-06-30
  • Direct synthesis of high-quality nitrogen-doped graphene via ion implantation
    Carbon (IF 7.082) Pub Date : 2018-06-27
    Yunbiao Zhao, Xu Wang, Engang Fu, Dong Han, Peipei Wang, Zaoming Wu, Yi Chen, Yuhan Chen, Ziqiang Zhao
    更新日期:2018-06-28
  • Reducing Lattice Thermal Conductivity in Schwarzites via Engineering the Hybridized Phonon Modes
    Carbon (IF 7.082) Pub Date : 2018-06-27
    Zhongwei Zhang, Shiqian Hu, Tsuneyoshi Nakayama, Jie Chen, Baowen Li
    更新日期:2018-06-28
  • Flexible binderless capacitors based on P- and N-containing fibrous activated carbons from denim cloth waste
    Carbon (IF 7.082) Pub Date : 2018-06-27
    Tomás Cordero-Lanzac, Francisco J. García-Mateos, Juana M. Rosas, José Rodríguez-Mirasol, Tomás Cordero
    更新日期:2018-06-28
  • Tailoring of Polycrystalline Diamond Surfaces from Hydrophilic to Superhydrophobic via Synergistic Chemical plus Micro-structuring Processes
    Carbon (IF 7.082) Pub Date : 2018-06-27
    A. Gabriela Montaño-Figueroa, Jesus J. Alcantar-Peña, Pablo Tirado, Alejandro Abraham, Elida de Obaldia, Orlando Auciello
    更新日期:2018-06-28
  • Steam engraving optimization of graphitic carbon nitride with enhanced photocatalytic hydrogen evolution
    Carbon (IF 7.082) Pub Date : 2018-06-26
    Zhou Chen, Xiang Yu, Qiuhui Zhu, Tingting Fan, Qiuling Wu, Lizhong Zhang, Jianhui Li, Weiping Fang, Xiaodong Yi
    更新日期:2018-06-27
  • Programmable actuating systems based on swimming fiber robots
    Carbon (IF 7.082) Pub Date : 2018-06-26
    Hao Sun, Meng Liao, Jianfeng Li, Chao Zhou, Jue Deng, Xuemei Fu, Songlin Xie, Bo Zhang, Yizheng Wu, Bingjie Wang, Xuemei Sun, Huisheng Peng
    更新日期:2018-06-27
  • 更新日期:2018-06-27
  • Hydrothermally reduced graphene oxide for the effective wrapping of sulfur particles showing long term stability as electrodes for Li-S batteries
    Carbon (IF 7.082) Pub Date : 2018-06-26
    J.L. Gómez-Urbano, J.L. Gómez-Cámer, C. Botas, N. Díez, J.M. López del Amo, L.M. Rodríguez-Martinez, D. Carriazo, T. Rojo
    更新日期:2018-06-27
  • 更新日期:2018-06-27
  • Taming the magnetoresistance anomaly in graphite
    Carbon (IF 7.082) Pub Date : 2018-06-22
    Bruno Cury Camargo, Walter Escoffier
    更新日期:2018-06-22
  • Effective light scattering and charge separation in nanodiamond@g-C3N4 for enhanced visible-light hydrogen evolution
    Carbon (IF 7.082) Pub Date : 2018-06-22
    Li-Xia Su, Qun-Zeng Huang, Qing Lou, Zhi-Yu Liu, Jun-Lu Sun, Zong-Tao Zhang, Shi-Rong Qin, Xing Li, Jin-Hao Zang, Lin Dong, Chong-Xin Shan
    更新日期:2018-06-22
  • Nanostructure Analysis of Gasoline Turbocharged Direct Injection and Diesel Soot-in-oil and Comparison with Carbon black
    Carbon (IF 7.082) Pub Date : 2018-06-22
    S.A. Pfau, A. La Rocca, E. Haffner-Staton, G.A. Rance, M.W. Fay, R.J. Brough, S. Malizia
    更新日期:2018-06-22
  • Novel approach towards the synthesis of carbon-based transparent highly potent flame retardant
    Carbon (IF 7.082) Pub Date : 2018-06-22
    Rahul V. Khose, Dattatray A. Pethsangave, Pravin H. Wadekar, Alok K. Ray, Surajit Some
    更新日期:2018-06-22
  • 更新日期:2018-06-22
  • Additive-free electrode fabrication with reduced graphene oxide using supersonic kinetic spray for flexible lithium-ion batteries
    Carbon (IF 7.082) Pub Date : 2018-06-21
    Seong Dae Kim, Jong-Gun Lee, Tae-Gun Kim, Kuldeep Rana, Jong Yeob Jeong, Jong Hyeok Park, Sam S. Yoon, Jong-Hyun Ahn
    更新日期:2018-06-22
  • MnO2 nanoparticles anchored on carbon nanotubes with hybrid supercapacitor-battery behavior for ultrafast lithium storage
    Carbon (IF 7.082) Pub Date : 2018-06-21
    Datao Wang, Ke Wang, Li Sun, Hengcai Wu, Jing Wang, Yuxing Zhao, Lingjia Yan, Yufeng Luo, Kaili Jiang, Qunqing Li, Shoushan Fan, Ju Li, Jiaping Wang
    更新日期:2018-06-22
  • Antimicrobial graphene nanoplatelets coatings for silicone catheters
    Carbon (IF 7.082) Pub Date : 2018-06-19
    R.N. Gomes, I. Borges, Andreia T. Pereira, A.F. Maia, M. Pestana, F.D. Magalhães, A.M. Pinto, I.C. Gonçalves
    更新日期:2018-06-19
  • Mesoscopic friction and network morphology control the mechanics and processing of carbon nanotube yarns
    Carbon (IF 7.082) Pub Date : 2018-06-19
    Yuezhou Wang, Hao Xu, Grigorii Drozdov, Traian Dumitrică
    更新日期:2018-06-19
  • Hierarchically structured VO2@PPy core-shell nanowire arrays grown on carbon nanotube fibers as advanced cathodes for high-performance wearable asymmetric supercapacitors ☆
    Carbon (IF 7.082) Pub Date : 2018-06-18
    Ping Man, Qichong Zhang, Juan Sun, Jiabin Guo, Xiaona Wang, Zhenyu Zhou, Bing He, Qiulong Li, Liyan Xie, Jingxin Zhao, Chaowei Li, Qingwen Li, Yagang Yao
    更新日期:2018-06-18
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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