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Zhong-Xia Wang, Fen-Ying Kong, Wei Wang
Graphene quantum dots-like structures of highly enriched nitrogen-based dual-color single-functional polymer carbon nanosheets (GLNPCNs) with an average diameter as large as 170 nm (~5 layers) are prepared by a facile hydrothermal method. Intermolecular C5H5N5···C5H5N5 or/and C2H5OH chemical polymerization interactions in the liquid state of the peripheral crown ether-like "hole" decorated compound GLNPCNs lead to a fascinating 2D supramolecular polymer architecture, which exhibits near-ultraviolet (NUV) fluorescence, narrow full width at half maximum, and excellent practical application capability...
October 20, 2016: Chemistry: a European Journal
Da Huang, Zhi Yang, Xiaolin Li, Liling Zhang, Jing Hu, Yanjie Su, Nantao Hu, Guilin Yin, Dannong He, Yafei Zhang
Graphene is an ideal candidate for gas sensing due to its excellent conductivity and large specific surface areas. However, it usually suffers from sheet stacking, which seriously debilitates its sensing performance. Herein, we demonstrate a three-dimensional conductive network based on stacked SiO2@graphene core-shell hybrid frameworks for enhanced gas sensing. SiO2 spheres are uniformly encapsulated by graphene oxide (GO) through an electrostatic self-assembly approach to form SiO2@GO core-shell hybrid frameworks, which are reduced through thermal annealing to establish three-dimensional (3D) conductive sensing networks...
October 20, 2016: Nanoscale
Suchithra Padmajan Sasikala, Kai Huang, Baptiste Giroire, Prem Prabhakaran, Lucile Henry, Alain Pénicaud, Philippe Poulin, Cyril Aymonier
We report the exfoliation of graphite and simultaneous N doping of graphene by two methods; by supercritical ammonia treatment and by liquid phase exfoliation with NH4OH. While the supercritical ammonia allowed N doping at a level of 6.4 at.% in 2 h, the liquid phase exfoliation with NH4OH allowed N doping at a level of 2.7at.% in 6 h. The N doped graphene obtained via supercritical ammonia route were few layers (<5), showed large lateral flake size (~8µm), low defect density (ID/IG<0.6) in spite of their high level of N doping...
October 20, 2016: ACS Applied Materials & Interfaces
Xin Tian, Zaixing Yang, Guangxin Duan, Anqing Wu, Zonglin Gu, Leili Zhang, Chunying Chen, Zhifang Chai, Cuicui Ge, Ruhong Zhou
Graphene and graphene-based nanomaterials are broadly used for various biomedical applications due to their unique physiochemical properties. However, how graphene-based nanomaterials interact with biological systems has not been thoroughly studied. This study shows that graphene oxide (GO) nanosheets retard A549 lung carcinoma cell migration through nanosheet-mediated disruption of intracellular actin filaments. After GO nanosheets treatment, A549 cells display slower migration and the structure of the intracellular actin filaments is dramatically changed...
October 20, 2016: Small
Andreas Brenneis, Felix Schade, Simon Drieschner, Florian Heimbach, Helmut Karl, Jose A Garrido, Alexander W Holleitner
For future on-chip communication schemes, it is essential to integrate nanoscale materials with an ultrafast optoelectronic functionality into high-frequency circuits. The atomically thin graphene has been widely demonstrated to be suitable for photovoltaic and optoelectronic devices because of its broadband optical absorption and its high electron mobility. Moreover, the ultrafast relaxation of photogenerated charge carriers has been verified in graphene. Here, we show that dual-gated graphene junctions can be functional parts of THz-circuits...
October 20, 2016: Scientific Reports
Hangil Lee, Yeonwoo Kim, Min Ji Kim, Ki-Jeong Kim, Byung-Kwon Kim
In order to compare the catalytic activities of reduced graphene oxide (rGO), graphene oxide (GO), and graphene, we conducted oxidation of 2-aminothiophenol (2-ATP) and reduction of nitrobenzene (NB) in their presence by using high-resolution photoemission spectroscopy (HRPES). In addition, we determined conversion rates of CO to CO2 in the presence of these catalysts by performing a residual gas analyzer (RGA) under a UHV condition, Orange II and methylene blue degradations UV-vis spectrophotometry, and electrochemistry (EC) measurements in an aqueous solution, as well as by obtaining cyclic voltammograms and determining the change of the condition of electrodes before and after the oxidation of 2-ATP...
October 20, 2016: Scientific Reports
Matthew Yankowitz, K Watanabe, T Taniguchi, Pablo San-Jose, Brian J LeRoy
Combining atomically-thin van der Waals materials into heterostructures provides a powerful path towards the creation of designer electronic devices. The interaction strength between neighbouring layers, most easily controlled through their interlayer separation, can have significant influence on the electronic properties of these composite materials. Here, we demonstrate unprecedented control over interlayer interactions by locally modifying the interlayer separation between graphene and boron nitride, which we achieve by applying pressure with a scanning tunnelling microscopy tip...
October 20, 2016: Nature Communications
Xiaopeng Wang, Jian Gao, Zhihua Cheng, Nan Chen, Liangti Qu
A new type of responsive battery with the fascinating feature of pressure perceptibility has been developed, which can spontaneously, timely and reliably control the power outputs (e.g., current and voltage) in response to pressure changes. The device design is based on the structure of the Zn-air battery, in which graphene-coated sponge serves as pressure-sensitive air cathode that endows the whole system with the capability of self-controlled energy release. The responsive batteries exhibit superior battery performance with high open-circuit voltage (1...
October 20, 2016: Angewandte Chemie
Amira Alazmi, Omar El Tall, Shahid Rasul, Mohamed N Hedhili, Shashikant P Patole, Pedro M F J Costa
The impact of post-synthesis processing in reduced graphene oxide materials for supercapacitor electrodes has been analyzed. A comparative study of vacuum, freeze and critical point drying was carried out for hydrothermally reduced graphene oxide demonstrating that the optimization of the specific surface area and preservation of the porous network are critical to maximize its supercapacitance performance. As described below, using a supercritical fluid as the drying medium, unprecedented values of the specific surface area (364 m(2) g(-1)) and supercapacitance (441 F g(-1)) for this class of materials have been achieved...
October 20, 2016: Nanoscale
Yuqin Zou, Alex S Walton, Ian A Kinloch, Robert A W Dryfe
A study of the differences between the capacitance of freshly exfoliated highly ordered pyrolytic graphite (HOPG, sample denoted FEG), HOPG aged in air (denoted AAG) and aged in an inert atmosphere (hereafter IAG) is presented in this work. The FEG is found to be more hydrophilic than AAG and IAG since the aqueous electrolyte contact angle (CA) increases from 61.7o to 72.5o and 81.8o after aging in Ar and air, respectively. Electrochemical impedance spectroscopy (EIS) shows the FEG has higher intrinsic capacitance (6...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Gurpreet S Suri, Amritvir Kaur, Tapas Sen
Persistent development in nanomedicine has enabled successful nanosizing of most drug samples which, in turn, imparts remarkable properties to the drugs such as enhanced solubility and bioavailability for the applications in drug delivery. In this context, several review articles are available in scientific domain covering inorganic nanoparticles such as Au, Ag, SPIONs, Qdots, carbon nanotubes and graphene; however, this review covers the development of drug nanoparticles together with their possibilities and limitation from fabrication (bottom up vs top down) to application in drug delivery during the last 5 years...
October 19, 2016: Nanomedicine
Tan Xing, Srikanth Mateti, Lu Hua Li, Fengxian Ma, Aijun Du, Yury Gogotsi, Ying Chen
Two-dimensional (2D) materials can be produced using ball milling with the help of liquid surfactants or solid exfoliation agents, as ball milling of bulk precursor materials usually produces nanosized particles because of high-energy impacts. Post-milling treatment is thus needed to purify the nanosheets. We show here that nanosheets of graphene, BN, and MoS2 can be produced by ball milling of their bulk crystals in the presence of ammonia or a hydrocarbon ethylene gas and the obtained nanosheets remain flat and maintain their single-crystalline structure with low defects density even after a long period of time; post-milling treatment is not needed...
October 19, 2016: Scientific Reports
Zhu-Jun Wang, Jichen Dong, Yi Cui, Gyula Eres, Olaf Timpe, Qiang Fu, Feng Ding, R Schloegl, Marc-Georg Willinger
In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combine isothermal growth and etching experiments with in situ scanning electron microscopy to reveal the stacking sequence and interlayer coupling strength in few-layer graphene...
October 19, 2016: Nature Communications
Xiaohu Zheng, Lei Gao, Quanzhou Yao, Qunyang Li, Miao Zhang, Xiaoming Xie, Shan Qiao, Gang Wang, Tianbao Ma, Zengfeng Di, Jianbin Luo, Xi Wang
Two-dimensional (2D) materials possess outstanding lubrication property with their thicknesses down to a few atomic layers, but they are easily susceptible to sliding induced degradation or ubiquitous chemical modification. Maintaining the superior lubricating performance of 2D materials in a harsh working environment is highly desirable yet grandly challenging. Here we show that by proper alignment of graphene on a Ge(111) substrate, friction of graphene could be well preserved at an ultra-low level even after fluorination or oxidation...
October 19, 2016: Nature Communications
Jie Chen, Jens H Walther, Petros Koumoutsakos
The increasing power density and the decreasing dimensions of transistors present severe thermal challenges to the design of modern microprocessors. Furthermore, new technologies such as three-dimensional chip-stack architectures require novel cooling solutions for their thermal management. Here, we demonstrate, through transient heat-dissipation simulations, that a covalently bonded graphene-carbon nanotube (G-CNT) hybrid immersed in water is a promising solution for the ultrafast cooling of such high-temperature and high heat-flux surfaces...
October 19, 2016: Nanotechnology
L J P Xavier, D R da Costa, A Chaves, J M Pereira, G A Farias
We investigate localized states of a quantum ring confinement in monolayer graphene defined by a circular mass-related potential, which can be induced e.g. by interaction with a substrate that breaks the sublattice symmetry, where a circular line defect provides a change in the sign of the induced mass term along the radial direction. Electronic properties are calculated analytically within the Dirac-Weyl approximation in the presence of an external magnetic field. Analytical results are also compared with those obtained by the tight-binding approach...
October 19, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Zhenning Yu, Lei Zou, Yanli Chen, Jianzhuang Jiang
A facile approach was developed for preparing the multilayer hybrid films of mixed (phthalocyaninato)(porphyrinato) europium (III) triple-decker compound (Pc)Eu(Pc)Eu[trans-T(COOCH3)2PP] (1) and graphene oxide (GO) using the solution-processing QLS method. Combination in the nature of relatively high conductivity and great surface area for GO with the electroactive and semiconductive triple-decker compound in ITO electrode renders the hybrid film excellent sensing property for H2O2, due to the optimized triple-decker molecular packing in the uniform-sized nanoparticles (ca...
October 19, 2016: ACS Applied Materials & Interfaces
Lele Peng, Yue Zhu, Hongsen Li, Guihua Yu
State-of-the-art energy storage devices are capable of delivering reasonably high energy density (lithium ion batteries) or high power density (supercapacitors). There is an increasing need for these power sources with not only superior electrochemical performance, but also exceptional flexibility. Graphene has come on to the scene and advancements are being made in integration of various electrochemically active compounds onto graphene or its derivatives so as to utilize their flexibility. Many innovative synthesis techniques have led to novel graphene-based hybrid two-dimensional nanostructures...
October 19, 2016: Small
Kan Zhang, Shansheng Yu, Baoming Jv, Weitao Zheng
In this work, the adsorption of Rhodamine 6G molecules on some graphene substrates is investigated using density functional theory. Some simple models, such as those of perfect graphene, defective graphene, *O/*OH modified graphene and B/N doping graphene, are constructed as substrates to simulate graphene oxide and B/N doping graphene sheets. It is demonstrated that the interactions of Rhodamine 6G molecules with graphene materials are strong. In particular, the amine group of Rhodamine 6G molecules can favor the formation of a chemical bond with some graphene substrates characterized by under-coordinated atoms...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Yang Ruan, Yudan Zhu, Yumeng Zhang, Qingwei Gao, Xiaohua Lu, Linghong Lu
Residual Mg2+ could reduce the performance of lithium-ion batteries, but separating Mg2+ and Li+ is difficult because of their similar ionic properties. Inspired by the high selectivity of biological Mg2+ channels, this work investigates the ability of graphene-based nanopores with different diameters (0.789, 1.024 and 1.501 nm) to separate Mg2+ and Li+ under a series of transmembrane voltages using atomistic simulations. We analyzed the spatial distribution of molecules in the pore vicinity, ionic hydration structure properties, and potential of mean force of ions traveling through the nanopores...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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