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https://www.readbyqxmd.com/read/28813609/co-assembly-kinetics-of-graphene-oxide-and-block-copolymers-at-the-water-oil-interface
#1
Dayong Chen, Zhiwei Sun, Thomas P Russell, Lihua Jin
The co-assembly kinetics of graphene oxide (GO) nanosheets and diblock copolymers at the water/toluene interface is probed by tracking the dynamic interfacial tension using pendant drop tensiometry. The diblock copolymer significantly enhances the surfactancy of the GO nanosheets at the interface. It is found that diblock copolymers rapidly adsorb to the water/toluene interface and enhance the adsorption affinity of GO nanosheets to the interface. The continuous adsorption of GO at the interface leads to a random loose packing state, at which the adsorbed GO and diblock copolymers start to form an elastic film...
August 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28813368/electronic-transport-properties-of-graphene-doped-by-gallium
#2
Jindřich Mach, Pavel Procházka, Miroslav Bartošík, David Nezval, Jakub Piastek, Jan Hulva, Vojtěch Švarc, Martin Konečný, Lukáš Kormoš, Tomas Sikola
In this work we present the effect of low dose gallium (Ga) deposition (< 4 ML) performed in UHV (10-7 Pa) on the electronic doping and charge carrier scattering in graphene grown by chemical vapor deposition (CVD). In-situ graphene transport measurements performed with a graphene field-effect transistor (FET) structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping)...
August 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28812773/side-by-side-observation-of-the-interfacial-improvement-of-vertical-graphene-coated-silicon-nanocone-anodes-for-lithium-ion-batteries-by-patterning-technology
#3
Chao Wang, Fei Luo, Hao Lu, Bonan Liu, Geng Chu, Baogang Quan, Junjie Li, Changzhi Gu, Hong Li, Liquan Chen
We report that vertical graphene coating can greatly improve the electrochemical performance and the interfacial stability of silicon nanocone (SNC) anodes for lithium-ion batteries. The coating patterning technology is innovatively employed for side-by-side demonstration of the exclusive influences of graphene coating on the solid-electrolyte interphase (SEI) formation and the structural stability of the SNC electrode. The silicon nanocone-graphene (SNC-G) electrode achieves a longer cycle life (1715 cycles), higher Coulombic efficiency (average 98...
August 16, 2017: Nanoscale
https://www.readbyqxmd.com/read/28812234/temperature-dependence-of-band-gap-in-mose2-grown-by-molecular-beam-epitaxy
#4
Byoung Ki Choi, Minu Kim, Kwang-Hwan Jung, Jwasoon Kim, Kyu-Sang Yu, Young Jun Chang
We report on a temperature-dependent band gap property of epitaxial MoSe2 ultrathin films. We prepare uniform MoSe2 films epitaxially grown on graphenized SiC substrates with controlled thicknesses by molecular beam epitaxy. Spectroscopic ellipsometry measurements upon heating sample in ultra-high vacuum showed temperature-dependent optical spectra between room temperature to 850 °C. We observed a gradual energy shift of optical band gap depending on the measurement temperature for different film thicknesses...
August 15, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28812083/visible-light-enhanced-power-generation-in-microbial-fuel-cells-coupling-with-3d-nitrogen-doped-graphene
#5
Dan Guo, Rong-Bin Song, Hao-Hua Shao, Jian-Rong Zhang, Jun-Jie Zhu
A new visible-light-assisted microbial fuel cell composed of a three-dimensional nitrogen-doped graphene self-standing sponge anode and a photoresponsive cathode has been developed for achieving multiple energy conversion and a higher power output.
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28811577/dirac-point-induced-ultralow-threshold-laser-and-giant-optoelectronic-quantum-oscillations-in-graphene-based-heterojunctions
#6
Golam Haider, Rini Ravindranath, Tzu-Pei Chen, Prathik Roy, Pradip Kumar Roy, Shu-Yi Cai, Huan-Tsung Chang, Yang-Fang Chen
The occurrence of zero effective mass of electrons at the vicinity of the Dirac point is expected to create new paradigms for scientific research and technological applications, but the related discoveries are rather limited. Here, we demonstrate that a simple architecture composed of graphene quantum dots sandwiched by graphene layers can exhibit several intriguing features, including the Dirac point induced ultralow-threshold laser, giant peak-to-valley ratio (PVR) with ultra-narrow spectra of negative differential resistance and quantum oscillations of current as well as light emission intensity...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28811526/observation-of-the-unexpected-morphology-of-graphene-wrinkle-on-copper-substrate
#7
Wen Wang, Shudu Yang, Ashu Wang
Graphene, a two-dimensional material, has a wide range of unique properties and could be used in the development of varieties of mechanic, electronic and photonic devices, therefore methods to synthesis large-area high-quality graphene films are urgently required. Chemical vapor deposition (CVD) has been of particular interest recently due to its simplicity and low cost. However, because of the mismatch of thermal expansion coefficients, high densities of wrinkles are commonly observed. Despite their prevalence and potential impact on large-scale graphene properties, relatively little is known about their structural morphology and formation mechanism...
August 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28811470/bias-induced-up-to-100-spin-injection-and-detection-polarizations-in-ferromagnet-bilayer-hbn-graphene-hbn-heterostructures
#8
M Gurram, S Omar, B J van Wees
We study spin transport in a fully hBN encapsulated monolayer-graphene van der Waals heterostructure at room temperature. A top-layer of bilayer-hBN is used as a tunnel barrier for spin-injection and detection in graphene with ferromagnetic cobalt electrodes. We report surprisingly large and bias-induced (differential) spin-injection (detection) polarizations up to 50% (135%) at a positive voltage bias of + 0.6 V, as well as sign inverted polarizations up to -70% (-60%) at a reverse bias of -0.4 V. This demonstrates the potential of bilayer-hBN tunnel barriers for practical graphene spintronics applications...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28811023/agnps-3d-nanostructure-enhanced-electrochemiluminescence-of-cdse-quantum-dot-coupled-with-strand-displacement-amplification-for-sensitive-biosensing-of-dna
#9
Meng Jiao, Guifen Jie, Lu Tan, Shuyan Niu
A novel strategy using Ag nanoparticles-3D (AgNPs-3D) nanostructure enhanced electrochemiluminescence (ECL) of CdSe quantum dots (QDs) coupled with strand displacement amplification (SDA) for sensitive biosensing of DNA was successfully designed. The prepared CdSe QDs with intense ECL were assembled on the poly (diallyldimethylammonium chloride) (PDDA) graphene oxide (GO) nanocomposites modified electrode, then gold nanoparticles (NPs) as the quenching probe was conjugated to the QDs, ECL signal was efficiently quenched...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28811015/multiple-targeted-graphene-based-nanocarrier-for-intracellular-imaging-of-mrnas
#10
Ying Wang, Zhaohui Li, Misha Liu, Jinjin Xu, Dehong Hu, Yuehe Lin, Jinghong Li
Simultaneous detection and imaging of multiple intracellular messenger RNA (mRNAs) hold great significant for early cancer diagnostics and preventive medicine development. Herein, we propose a multiple-targeted graphene oxide (GO) nanocarrier that can simultaneously detect and image different type mRNAs in living cells. First of all, in vitro detection of multiple targets have been realized successfully based on the multiple-targeted GO nanocarrier with linear relationship ranging from 3 nM to 200 nM, as well as sensitive detection limit of 1...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28810208/tungsten-doped-tio2-reduced-graphene-oxide-nano-composite-photocatalyst-for-degradation-of-phenol-a-system-to-reduce-surface%C3%A2-and-bulk-electron-hole-recombination
#11
Manisha Yadav, Asha Yadav, Rohan Fernandes, Yaksh Popat, Michele Orlandi, Alpa Dashora, D C Kothari, Antonio Miotello, B L Ahuja, Nainesh Patel
Recombination of photogenerated charges is the main factor affecting the photocatalytic activity of TiO2. Here, we report a combined strategy of suppressing both the bulk as well as the surface recombination processes by doping TiO2 with tungsten and forming a nanocomposite with reduced graphene oxide (rGO), respectively. Sol-gel method was used to dope and optimize the concentration of W in TiO2 powder. UV-Vis, XPS, PL and time resolved PL spectra along with DFT calculations indicate that W(6+) in TiO2 lattice creates an impurity level just below the conduction band of TiO2 to act as a trapping site of electrons, which causes to improve the lifetime of the photo-generated charges...
August 12, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28810193/kinetics-and-mechanism-of-antibacterial-activity-and-cytotoxicity-of-ag-rgo-nanocomposite
#12
Marjan Moghayedi, Elaheh K Goharshadi, Kiarash Ghazvini, Hossein Ahmadzadeh, Laleh Ranjbaran, Raheleh Masoudi, Ralf Ludwig
Nowadays, nanomaterials with remarkable antibacterial activity and low cytotoxicity attract much interest in research. By considering the antibacterial activity of Ag and graphene oxide (GO), the Ag-RGO nanocomposite was prepared by a one-pot and facile technique and it was used to evaluate its antibacterial activity and cytotoxicity against Escherichia coli and glioblastoma cancer cells (U87MG), respectively. The antibacterial activity was studied by micro-dilution and colony counting methods to investigate cell viability...
August 4, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28810137/time-gated-luminescence-imaging-of-singlet-oxygen-photoinduced-by-fluoroquinolones-and-functionalized-graphenes-in-daphnia-magna
#13
Tianlie Luo, Jingwen Chen, Bo Song, Hua Ma, Zhiqiang Fu, Willie J G M Peijnenburg
Singlet oxygen ((1)O2) can be photogenerated by photoactive xenobiotics and is capable of causing adverse effects due to its electrophilicity and its high reactivity with biological molecules. Detection of the production and distribution of (1)O2 in living organisms is therefore of great importance. In this study, a luminescent probe ATTA-Eu(3+) combined with time-gated luminescence imaging was adopted to detect the distribution and temporal variation of (1)O2 photoinduced by fluoroquinolone antibiotics and carboxylated/aminated graphenes in Daphnia magna...
July 29, 2017: Aquatic Toxicology
https://www.readbyqxmd.com/read/28809876/sub-100%C3%A2-%C3%A2-fs-tm-mgwo4-laser-at-2017%C3%A2-%C3%A2-nm-mode-locked-by-a-graphene-saturable-absorber
#14
Yicheng Wang, Weidong Chen, Mark Mero, Lizhen Zhang, Haifeng Lin, Zhoubin Lin, Ge Zhang, Fabian Rotermund, Young Jun Cho, Pavel Loiko, Xavier Mateos, Uwe Griebner, Valentin Petrov
We present the first sub-100 fs bulk solid-state laser in the 2-μm spectral range employing the monoclinic Tm(3+)-dopedMgWO4 crystal as an active medium. By applying a graphene-based saturable absorber and chirped mirrors for dispersion management, stable self-starting mode-locked operation at 2017 nm was achieved. Nearly Fourier-limited pulses as short as 86 fs featuring a bandwidth of 53 nm were generated at a repetition rate of 76 MHz. A pulse energy of 1.1 nJ was achieved at 87 MHz for a pulse duration of 96 fs...
August 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28809573/intrinsic-plasmon-phonon-interactions-in-highly-doped-graphene-a-near-field-imaging-study
#15
Francisco J Bezares, Adolfo De Sanctis, Jose R M Saavedra, Achim Woessner, Pablo Alonso-González, Iban Amenabar, Jianing Chen, Thomas Bointon, Siyuan Dai, Michael M Fogler, D N Basov, Rainer Hillenbrand, Monica Felicia Craciun, F Javier Garcia de Abajo, Saverio Russo, Frank H L Koppens
As a two-dimensional semi-metal, graphene offers clear advantages for plasmonic applications over conventional metals, such as stronger optical field confinement, in situ tunability and relatively low intrinsic losses. However, the operational frequencies at which plasmons can be excited in graphene are limited by the Fermi energy EF, which in practice can be controlled electrostatically only up to a few tenths of an electronvolt. Higher Fermi energies open the door to novel plasmonic devices with unprecedented capabilities, particularly at mid-infrared and shorter-wave infrared frequencies...
August 15, 2017: Nano Letters
https://www.readbyqxmd.com/read/28809537/confined-water-structure-dynamics-and-thermodynamics
#16
Sudip Chakraborty, Hemant Kumar, Chandan Dasgupta, Prabal K Maiti
Understanding the properties of strongly confined water is important for a variety of applications such as fast flow and desalination devices, voltage generation, flow sensing, and nanofluidics. Confined water also plays an important role in many biological processes such as flow through ion channels. Water in the bulk exhibits many unusual properties that arise primarily from the presence of a network of hydrogen bonds. Strong confinement in structures such as carbon nanotubes (CNTs) substantially modifies the structural, thermodynamic, and dynamic (both translational and orientational) properties of water by changing the structure of the hydrogen bond network...
August 15, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28809496/time-resolved-coherent-anti-stokes-raman-scattering-of-graphene-dephasing-dynamics-of-optical-phonon
#17
Juha Tapio Koivistoinen, Pasi Myllyperkiö, Mika Pettersson
We report dynamics of the G-mode in graphene probed with time-resolved coherent anti-Stokes Raman scattering measurements. By applying BOXCARS excitation geometry with three different excitation wavelengths various nonlinear processes can be selectively detected due to energy and momentum conservation and temporal sequence of the pulses. The Raman signal due to resonant coherent excitation of the G-mode shows exponential decay with lifetime of ~325 ± 50 fs. This decay time is shorter than expected based on the linewidth of the G-mode in the Raman spectrum...
August 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28809426/polarization-sensitive-and-broadband-germanium-sulfide-photodetectors-with-excellent-high-temperature-performance
#18
Dezhi Tan, Wenjin Zhang, Xiaofan Wang, Sandhaya Koirala, Yuhei Miyauchi, Kazunari Matsuda
Layered materials, such as graphene, transition metal dichalcogenides and black phosphorene, have been established rapidly as intriguing building blocks for optoelectronic devices. Here, we introduce highly polarization sensitive, broadband, and high-temperature-operation photodetectors based on multilayer germanium sulfide (GeS). The GeS photodetector shows a high photoresponsivity of about 6.8 × 10(3) A W(-1), an extremely high specific detectivity of 5.6 × 10(14) Jones, and broad spectral response in the wavelength range of 300-800 nm...
August 15, 2017: Nanoscale
https://www.readbyqxmd.com/read/28809067/in-situ-fabrication-of-mof-derived-co-co-layered-double-hydroxide-hollow-nanocages-graphene-composite-a-novel-electrode-material-with-superior-electrochemical-performance
#19
Xue Bai, Jingyuan Liu, Qi Liu, Rongrong Chen, Xiaoyan Jing, Bin Li, Jun Wang
Rational design of transition metal layered double hydroxide and graphene composite are vital important for designing high-performance supercapacitor electrodes. Although various methods have been performed, however, the realization of high-performance is still impeded by the agglomeration of graphene and layered double hydroxide. Here, metal-organic frameworks derived cobalt-cobalt layered double hydroxide (Co-Co LDH) hollow nanocages uniformly deposited on graphene nanosheets, are fabricated via facile in-situ co-deposition and thermal ion-exchange reaction...
August 15, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28808722/role-of-carboxylic-acid-groups-in-the-reduction-of-nitric-oxide-by-carbon-at-low-temperature-as-exemplified-by-graphene-oxide
#20
J Zhang, Q Gao, X M Li, J Z Zhou, X X Ruan, Q Liu, G R Qian, Z P Xu
Graphene oxide (GO) was utilized to investigate the role of carboxylic acid groups in the reduction of nitric oxide (NO) for the first time. As a result, GO with sufficient carboxylic acid groups reduced 45% of NO at 100 °C. However, GO without these oxygen-containing groups barely reduced NO (lower than 5%) under the same conditions. After reduction of NO, the carboxylic acid group content on GO decreased from 8.32 to 5.22 mmol g(-1). Simultaneously, the anhydride group content increased from 0.14 to 0.28 mmol g(-1)...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
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