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N-doped graphene (NG) was synthesized by annealing reduced graphene oxide (RGO) in an ammonia atmosphere. The dependence of the nitrogen content on the annealing temperature and the type of doping of NG were investigated. The photoluminescence (PL) properties of the RGO and NG samples were studied. The results show that RGO exhibits strong ultraviolet (UV) PL at 367nm. The PL of RGO can be quenched...
Polytetrafluoroethylene (PTFE) is one of the most widely used solid lubricants but suffers from a high wear rate which limits its applications. Here we report four orders of magnitude reduction in the steady state wear rate of PTFE due to graphene additives. The wear rate of unfilled PTFE was measured to be ∼0.4×10 −3 mm 3 /Nm which is reduced to ∼10 −7 mm 3 /Nm by...
We report unusual negative thermal expansion and viscoelastic properties in graphene oxide paper. The paper was prepared from aqueous GO dispersions using a simple vacuum evaporation technique. From room temperature to 150°C, this paper-like graphene oxide sheet exhibits a constant negative thermal expansion coefficient of −67×10 −6 /°C along the in-plane direction. Peculiar hysteresis loops...
Graphite oxide (GO)/ordered polyaniline (PANI) composites have been prepared through an in situ polymerization. TEM, XRD, FTIR and XPS analyses show that the PANI grew along the surface of exfoliated GO as a template to form a more ordered structure with high crystallinity during polymerization. Compared with pure PANI, both higher electrical conductivity and higher Seebeck coefficient of GO/PANI...
A one-pot solvothermal synthesis method was developed to prepare reduced graphene oxide (RGO) supported ferrite (MFe 2 O 4 , M=Mn, Zn, Co and Ni) hybrids using graphite oxide and metal ions (Fe 3+ and M 2+ ) as starting materials. The hybrids were characterized by X-ray powder diffraction, Raman spectra, field emission scanning electron microscopy, energy dispersive...
Novel magnetic resonance imaging (MRI) contrast agents composed of multiwalled carbon nanotubes decorated with magnetic iron oxide nanoparticles were explored. They were functionalized with multilayer polyelectrolytes through layer-by-layer assembling and were shown to be hydrophilic, biocompatible, and have a high MRI contrast. A targeted ligand folic acid was chemically bonded to the functionalized...
The effect of the type of carrier gas on the bulk density and microstructure distribution of carbon/carbon (C/C) composites fabricated by thermal gradient chemical vapor infiltration from propylene was investigated. The results show that the type of carrier gas has an appreciable influence on the radial distribution of density and microstructure of the C/C composites. When N 2 is used as carrier...
Better understanding of electron transfer (ET) taking place at the nano-bio interface can guide design of more effective functional materials used in fuel cells, biosensors, and medical devices. Single-walled carbon nanotube (SWCNT) coupled with biological enzymes serves as a model system for studying the ET mechanism, as demonstrated in the present study. SWCNT enhanced the activity of horseradish...
The interlayer sliding behavior of few-layer (3–8) graphene (FLG) is investigated using molecular dynamics simulations. A constant velocity is imposed on the top layer, inducing relative sliding between layers. With multiple interlayer interfaces, the sliding is found to present unique behavior, such as coherent sliding at multiple interfaces and a periodic layer-stacking transition, which is quite...
The stacking-dependent electronic structure and transport properties of bilayer graphene nanoribbons suspended between gold electrodes are investigated using density functional theory coupled with non-equilibrium Green’s functional method. We find substantially enhanced electron transmission as well as tunneling currents in the AA stacking of bilayer nanoribbons compared to either single-layer or...
Through the pyrolysis of acetylene at 450°C, large quantities of carbon nanocoils or carbon nanofibers can be synthesized selectively by controlling the Na:K molar ratio of water-soluble Na x K y catalysts. We found that the temperature adopted for pyrolysis is an important factor for selectively obtaining the different kinds of products. Because the Na x K y catalysts...
The evolution of solid state N-doping in graphene has been probed using X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectra show that the modification of graphene with N species can be achieved by urea attachment at annealing temperatures lower than 300°C. A transition from urea to amino species is observed at 400°C. At higher temperatures, pyridinic and graphitic type doping...
Bi(2,2′-bipyridyl)-pyrene derivative functionalized ruthenium(II) complexes anchored on graphene sheets (B-Ru-P/GS nanohybrid) by π–π interaction were fabricated. The formation of the nanohybrid was verified by atomic force microscopy, fluorescence spectra and Raman spectroscopy. An obvious and stable electrochemiluminescence of the B-Ru-P/GS nanohybrid at the electrode was revealed. A typical photoelectrical...
Simultaneous surface functionalization and reduction of graphene oxide (GO) was realized by simple refluxing of GO with octadecylamine (ODA) without the use of any reducing agents. The presence of the long octadecyl chain made the hydrophilic GO hydrophobic, evidenced by the selective dispersion of the ODA-functionalized GO (GO–ODA) in chloroform solvent rather than in water. Interestingly, different...
A novel electrochemical grafting of carbon nanotubes (CNTs) on the surfaces of carbon fibers using water as dispersive medium was achieved by the electrolysis of carboxylic acid-functionalized CNTs. The resulting CNT-hybridized carbon fibers showed a selective distribution of CNTs at active carbon sites on the fibers associated with the edge graphite layers and defects, without destroying the crystalline...
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