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https://www.readbyqxmd.com/read/28646193/fabrication-of-nitrogen-doped-nano-onions-and-their-electrocatalytic-activity-toward-the-oxygen-reduction-reaction
#1
E Y Choi, C K Kim
Nitrogen-doped nano-onions (NNO) were prepared as electrocatalytic materials for the oxygen reduction reaction (ORR). The nano-onions (NO), spherical graphitic material particles, were prepared by pyrolysis of nanodiamonds (ND). Oxidized NO (ONO) was prepared from NO by a modified Hummers' method, and this was mixed with urea, followed by pyrolysis, resulting in the formation of NNO. The nitrogen content and molar ratio of nitrogen-containing groups in the NNOs were varied by controlling the oxygen content of ONO to explore the effect of nitrogen content on the ORR activity...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646137/three-dimensional-multi-doped-porous-carbon-graphene-derived-from-sewage-sludge-with-template-assisted-fe-pillared-montmorillonite-for-enhanced-oxygen-reduction-reaction
#2
Meiqing Chen, Pingxiao Wu, Liya Chen, Shanshan Yang, Langfeng Yu, Yuefei Ding, Nengwu Zhu, Zhenqing Shi, Zehua Liu
Three-dimensional multi-doped porous carbon/graphene (Fe-Mt-SS-C) was prepared by carbonization of sewage sludge with template-assisted Fe-pillared montmorillonite. The material consisted of nanosheet- and particle- carbon had a high specific surface area (784.46 m(2)·g(-1)) and hierarchical porous structure of micro-, meso- and macropores. The prepared Fe-Mt-SS-C had a high degree of graphitization and large amount of defect atoms. The pyrolysis process made full use of the C, N, Fe, and S by turning them into the carbon framework of the as-obtained material in situ...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645377/electrical-probes-of-dna-binding-proteins
#3
Jacqueline K Barton, Phillip L Bartels, Yingxin Deng, Elizabeth O'Brien
A DNA electrochemistry platform has been developed to probe proteins bound to DNA electrically. Here gold electrodes are modified with thiol-modified DNA, and DNA charge transport chemistry is used to probe DNA binding and enzymatic reaction both with redox-silent and redox-active proteins. For redox-active proteins, the electrochemistry permits the determination of redox potentials in the DNA-bound form, where comparisons to DNA-free potentials can be made using graphite electrodes without DNA modification...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28644607/electrochemical-exfoliation-of-graphite-in-aqueous-sodium-halide-electrolytes-towards-low-oxygen-content-graphene-for-energy-and-environmental-applications
#4
Jose Maria Munuera, Juan Ignacio Paredes, Marina Enterria, Ana Pagán, Silvia Villar-Rodil, Manuel Fernando R Pereira, J I Martins, José L Figueiredo, Jose Luis Cenis, Amelia Martinez-Alonso, Juan Manuel D Tascon
Graphene and graphene-based materials have shown great promise in many technological applications, but their large-scale production and processing by simple and cost-effective means still constitute significant issues in the path of their widespread implementation. Here, we investigate a straightforward method for the preparation of a ready-to-use and low oxygen content graphene material that is based on electrochemical (anodic) delamination of graphite in aqueous medium with sodium halides as the electrolyte...
June 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28644481/redox-controlled-potassium-intercalation-into-two-polyaromatic-hydrocarbon-solids
#5
F Denis Romero, M J Pitcher, C I Hiley, G F S Whitehead, S Kar, A Y Ganin, D Antypov, C Collins, M S Dyer, G Klupp, R H Colman, K Prassides, M J Rosseinsky
Alkali metal intercalation into polyaromatic hydrocarbons (PAHs) has been studied intensely after reports of superconductivity in a number of potassium- and rubidium-intercalated materials. There are, however, no reported crystal structures to inform our understanding of the chemistry and physics because of the complex reactivity of PAHs with strong reducing agents at high temperature. Here we present the synthesis of crystalline K2Pentacene and K2Picene by a solid-solid insertion protocol that uses potassium hydride as a redox-controlled reducing agent to access the PAH dianions, and so enables the determination of their crystal structures...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28643788/terahertz-saturable-absorbers-from-liquid-phase-exfoliation-of-graphite
#6
Vezio Bianchi, Tian Carey, Leonardo Viti, Lianhe Li, Edmund H Linfield, A Giles Davies, Alessandro Tredicucci, Duhee Yoon, Panagiotis G Karagiannidis, Lucia Lombardi, Flavia Tomarchio, Andrea C Ferrari, Felice Torrisi, Miriam S Vitiello
Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643777/in-situ-targeted-mri-detection-of-helicobacter-pylori-with-stable-magnetic-graphitic-nanocapsules
#7
Yunjie Li, Xiaoxiao Hu, Ding Ding, Yuxiu Zou, Yiting Xu, Xuewei Wang, Yin Zhang, Long Chen, Zhuo Chen, Weihong Tan
Helicobacter pylori infection is implicated in the aetiology of many diseases. Despite numerous studies, a painless, fast and direct method for the in situ detection of H. pylori remains a challenge, mainly due to the strong acidic/enzymatic environment of the gastric mucosa. Herein, we report the use of stable magnetic graphitic nanocapsules (MGNs), for in situ targeted magnetic resonance imaging (MRI) detection of H. pylori. Several layers of graphene as the shell effectively protect the magnetic core from corrosion while retaining the superior contrast effect for MRI in the gastric environment...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643467/a-core-shell-satellite-structured-fe3-o4-g-c3-n4-ucnps-peg-for-t1-t2-weighted-dual-modal-mri-guided-photodynamic-therapy
#8
Lili Feng, Dan Yang, Fei He, Shili Gai, Chunxia Li, Yunlu Dai, Piaoping Yang
Reactive oxygen species (ROS) produced in the specific tumor site plays the key role in photodynamic therapy (PDT). Herein, a multifunctional nanoplatform is designed by absorbing ultrasmall upconversion nanoparticles (UCNPs) on mesoporous graphitic-phase carbon nitride (g-C3 N4 ) coated superparamagnetic iron oxide nanospheres, then further modified with polyethylene glycol (PEG)molecules (abbreviated as Fe3 O4 @g-C3 N4 -UCNPs-PEG). The inert g-C3 N4 layer between Fe3 O4 core and outer UCNPs can substantially depress the quenching effect of Fe3 O4 on the upconversion emission...
June 23, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28642943/aqueous-dispersions-of-nanostructures-formed-through-the-self-assembly-of-iminolipids-with-exchangeable-hydrophobic-termini
#9
Wen Li, Daryl McManus, Han Liu, Cinzia Casiraghi, Simon J Webb
The addition of amines to an aldehyde surfactant, which was designed to be analogous to didodecyldimethylammonium bromide, gave exchangeable "iminolipids" that self-assembled to give stable aqueous dispersions of nano-sized vesicles. For example, sonication of suspensions of the n-hexylamine-derived iminolipid gave vesicles 50 to 200 nm in diameter that could encapsulate a water-soluble dye. The iminolipids could undergo dynamic exchange with added amines, and the resulting equilibrium constants (Krel) were quantified by (1)H NMR spectroscopy...
June 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28642458/the-structure-and-hardness-of-the-highest-boride-of-tungsten-a-borophene-based-compound
#10
Nevill Gonzalez Szwacki
Two-dimensional systems have strengthened their position as a key materials for novel applications. Very recently, boron joined the distinguished group of elements confirmed to possess 2D allotropes, named borophenes. In this work, we explore the stability and hardness of the highest borides of tungsten, which are built of borophenes separated by metal atoms. We show that the WB3+x compounds have Vickers hardnesses approaching 40 GPa only for small values of x. The insertion of extra boron atoms is, in general, detrimental to the hardness of WB3 because it leads to the formation of quasi-planar boron sheets that are less tightly connected with the adjacent tungsten layers...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28641412/anti-perovskite-li-battery-cathode-materials
#11
Kwing To Lai, Iryna Antonyshyn, Yurii Prots, Martin Valldor
Through single-step solid-state reactions, a series of novel bichalcogenides with the general composition (Li2Fe)ChO (Ch = S, Se, Te) are successfully synthesized. (Li2Fe)ChO (Ch = S, Se) possess cubic anti-perovskite crystal structures, where Fe and Li are completely disordered on a common crystallographic site (3c). According to Goldschmidt calculations, Li(+) and Fe(2+) are too small for their common atomic position and exhibit large thermal displacements in the crys-tal structure models, implying high cation mobility...
June 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28640583/fluffy-and-ordered-graphene-multilayer-films-with-improved-electromagnetic-interference-shielding-over-x-band
#12
Zicheng Wang, Renbo Wei, Xiaobo Liu
Highly ordered nitrogen-doped graphene multilayer films with large interlayer void are successfully fabricated by thermal annealing the compact stacking graphene oxide/copper phthalocyanine (GO/CuPc) multilayer films. Scanning electron microscopic (SEM), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopic (XPS) and electrical conductivity measurements indicate that the breakaway of oxygen functional groups on/in the GO sheets at high temperature and the in-situ pyrolysis of CuPc molecules in the interlayer of graphene sheets synergistically facilitate the restoration of GO in graphitization, the effective nitrogen doping by replacing carbon atoms in graphene frameworks, the retention of layer-by-layer stacking structure of graphene sheets in plane and the formation of interlayer voids, leading to the enhancement in the electrical conductivity (3...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28639621/electronic-metal-support-interaction-enhanced-oxygen-reduction-activity-and-stability-of-boron-carbide-supported-platinum
#13
Colleen Jackson, Graham T Smith, David W Inwood, Andrew S Leach, Penny S Whalley, Mauro Callisti, Tomas Polcar, Andrea E Russell, Pieter Levecque, Denis Kramer
Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure...
June 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28635999/carbon-dots-promoted-vanadium-flow-batteries-for-all-climate-energy-storage
#14
Ying Zhou, Le Liu, Yi Shen, Lantao Wu, Lihong Yu, Feng Liang, Jingyu Xi
We report a one-pot solvothermal method to prepare a carbon dots decorated graphite felt (CDs/GF) electrode. The resulting CDs/GF shows excellent wettability and greatly enhanced activity towards vanadium redox couples. VFB with the CDs/GF electrode exhibits outstanding rate performance, superior cycling stability, and broad temperature adaptability from -20 to 60 °C.
June 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28635631/ag-nanoparticles-drop-casting-modification-of-screen-printed-electrodes-for-the-simultaneous-voltammetric-determination-of-cu-ii-and-pb-ii
#15
Clara Pérez-Ràfols, Julio Bastos-Arrieta, Núria Serrano, José Manuel Díaz-Cruz, Cristina Ariño, Joan de Pablo, Miquel Esteban
A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode...
June 21, 2017: Sensors
https://www.readbyqxmd.com/read/28634339/effective-synthesis-of-highly-oxidized-graphene-oxide-that-enables-wafer-scale-nanopatterning-preformed-acidic-oxidizing-medium-approach
#16
Chun-Hu Chen, Shin Hu, Jyun-Fu Shih, Chang-Ying Yang, Yun-Wen Luo, Ren-Huai Jhang, Chao-Ming Chiang, Yung-Jr Hung
Demand for rapid and massive-scale exfoliation of bulky graphite remains high in graphene commercialization and property manipulation. We report a procedure utilizing "preformed acidic oxidizing medium (PAOM)" as a modified version of the Hummers' method for fast and reliable synthesis of graphene oxide. Pre-mixing of KMnO4 and concentrated H2SO4 prior to the addition of graphite flakes enables the formation of effectively and efficiently oxidized graphene oxide (EEGO) featured by its high yields and suspension homogeneity...
June 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28633526/reduced-graphene-oxide-poly-acrylic-acid-aerogels-as-a-three-dimensional-replacement-for-metal-foil-current-collectors-in-lithium-ion-batteries
#17
Han Xiao, Joshua P Pender, Mackenzie Meece-Rayle, J Pedro de Souza, Kyle C Klavetter, Heonjoo Ha, Jie Lin, Adam Heller, Christopher J Ellison, Charles Buddie Mullins
We report the synthesis and properties of a low-density (~5 mg/cm3) and highly-porous (99.6% void space) three-dimensional reduced graphene oxide (rGO)/poly(acrylic acid) (PAA) nanocomposite aerogel as the scaffold for cathode materials in lithium-ion batteries (LIBs). The rGO-PAA is both simple and starts from readily-available graphite and PAA thereby providing a scalable fabrication procedure. The scaffold can support as much as a 75 mg/cm2 loading of LiFePO4 (LFP) in a ~ 430 µm thick layer, and the porosity of the aerogel is tunable by compression; the flexible aerogel can be compressed 30-fold (i...
June 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28632318/-the-easier-the-better-preparation-of-efficient-photocatalysts-metastable-poly-heptazine-imide-salts
#18
Zupeng Chen, Aleksandr Savateev, Sergey Pronkin, Vasiliki Papaefthimiou, Christian Wolff, Marc Georg Willinger, Elena Willinger, Dieter Neher, Markus Antonietti, Dariya Dontsova
Cost-efficient, visible-light-driven hydrogen production from water is an attractive potential source of clean, sustainable fuel. Here, it is shown that thermal solid state reactions of traditional carbon nitride precursors (cyanamide, melamine) with NaCl, KCl, or CsCl are a cheap and straightforward way to prepare poly(heptazine imide) alkali metal salts, whose thermodynamic stability decreases upon the increase of the metal atom size. The chemical structure of the prepared salts is confirmed by the results of X-ray photoelectron and infrared spectroscopies, powder X-ray diffraction and electron microscopy studies, and, in the case of sodium poly(heptazine imide), additionally by atomic pair distribution function analysis and 2D powder X-ray diffraction pattern simulations...
June 20, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28631867/visible-light-irradiated-graphitic-carbon-nitride-g-c3n4-photocatalyzed-cation-radical-diels-alder-reactions-with-dioxygen-as-sustainable-mediator-for-photoinduced-electrons
#19
Yubao Zhao, Markus Antonietti
Photocatalytic Diels-Alder (D-A) reaction with electron rich olefins is realized by graphitic carbon nitride (g-C3N4) under visible light irradiation and aerobic condition. This heterogeneous photo-redox reaction system is highly efficient, and apparent quantum yield reaches a remarkable value of 47 % for the model reaction. Dioxygen plays a critical role as electron mediator, which is distinct from the previous reports in the homogeneous Ru(II) complex photo-redox system. Moreover, the reaction intermediate vinylcyclobutane is captured and monitored during the reaction, serving as a direct evidence for the proposed reaction mechanism...
June 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28631125/upgraded-modified-forms-of-bituminous-coal-for-the-removal-of-safranin-t-dye-from-aqueous-solution
#20
Mohamed Shaban, Mostafa R Abukhadra, Mohamed G Shahien, Aftab Aslam Parwaz Khan
Natural bituminous coal was used as a precursor in the synthesis of different modified products. The modification of coal was performed by treating it with nitric acid (N-coal), coating its surface by zinc oxide nanoparticles (Z-coal), and converting it into porous graphite (PG). The effect of modification processes on the structures, morphologies, and optical properties was followed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), and UV/VIS spectrophotometer analysis...
June 19, 2017: Environmental Science and Pollution Research International
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