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The influence of milling energy on the dispersion and evolution of multi-walled carbon nanotubes (MWCNTs) in titanium (Ti) metal matrix composites (TMCs) prepared via powder metallurgy has been investigated. High energy ball milling (HEBM) was employed to disperse MWCNTs (0.5 wt.%) into Ti matrix in two controlled ball milling processes: with and without in-situ formation of titanium carbide (TiC)...
In this study, we report a feasible method to synthesize a ternary nanocomposite, molybdenum disulfide/polyaniline/reduced graphene oxide aerogel (MoS2/PANI/rGO), via a two-step approach. Molybdenum disulfide/polyaniline (MoS2/PANI) is prepared by in situ polymerization. Graphene oxide is well-dispersed by loading MoS2/PANI nanoparticles (50–80 nm in size) and reduced using urea via a hydrothermal...
The structure and the low-energy phonon dispersion of graphene (Gr) on Ni(111) have been experimentally investigated with helium atom scattering (HAS). The Rayleigh mode observed for Gr/Ni(111) is almost identical to the one measured on clean Ni(111). The energy of the flexural ZA mode at the Γ¯ point was found to be ∼20 meV, significantly lower than the value predicted by recent DFT calculations...
N-doped microporous carbon nanospheres (MCNs) are prepared directly from the as-prepared mesoporous silica nanospheres (MSNs) with a disordered pore structure by a new, simple and direct carbonization method. The as-prepared MSNs containing cetylpyridinium bromide (CTPB) template are effective for direct carbonization. Neither MSN with a two-dimensional hexagonal pore symmetry nor MSN with cetyltrimethylammonium...
The structure of multilayer graphene domains on Cu foil is revealed with atomic force microscopy and theoretical analysis. The phase images of force microscopy enable the separation of the graphene domains from the naked areas of Cu foil. Furthermore, the phase images enable the discrimination of the different graphene layers and structures. For example, some of small graphene layers show a darker...
The relationship between the 2D and G band intensities and the number of walls of a multiwalled carbon nanotube was investigated by tip-enhanced Raman spectroscopy, which enables spatial resolution of nanometer order. The 2D band to G band integrated intensity ratio was found to be sensitive to the number of carbon nanotube walls. Furthermore, the 2D band intensity was enhanced by the intertube interaction...
As a member of the ternary metal oxide family, nickel cobaltite is considered as a promising electrode material. This is due to its high theoretical capacity, low diffusional resistance to protons, ease of electrolyte penetration, superior ionic/electronic conductivity and higher electrochemical activity compared to single metallic oxides such as NiO or Co3O4. However, NiCo2O4's relatively low electrical...
We report the preparation of a carbon aerogel (CA) material utilizing the simultaneous co-assembly of organic and inorganic precursors, having a high Brunauer–Emmet–Teller surface area of 2600 m2/g, through a one-step sol–gel process. This CA was characterized using different spectroscopic and microscopic techniques. The as-synthesized CA with its tunable porosity, high mechanical strength, transport...
The environment dependent interatomic potential (EDIP) including Ziegler–Biersack–Littermark (ZBL) interactions for close encounters is applied to cascades starting from a host atom and from an interstitial atom. We find the room temperature displacement threshold to be 25 eV, increasing to 30 eV at 900 K. The latter correlates well with the measured threshold for vacancy production. Additionally,...
Endohedral molecular magnets, e.g. as realized in fullerenes containing DySc2N, are promising candidates for molecular electronics and quantum information processing. For their functionalization an ultrafast local magnetization control is essential. Using full ab initio quantum chemistry calculations we predict the emergence of charge current loops in fullerenes with an associated orbital magnetic...
Large holes in graphene membranes were recently shown to heal, either at room temperature during a low energy STEM experiment, or by annealing at high temperatures. However, the details of the healing mechanism remain unclear. We carried out fully atomistic reactive molecular dynamics simulations in order to address these mechanisms under different experimental conditions. Our results show that, if...
Global warming has become a crucial issue and various efforts have been made to mitigate the emission of CO2, the most dominant greenhouse gas. Adsorption is considered a promising technology for CO2 capture, and carbon materials are good candidates for CO2 adsorption. In this study, highly porous carbons were prepared from polyvinylidene fluoride by single-step physical activation under CO2 flow...
A series of nitrogen containing activated carbons (NAC-1.5-y) with surface areas and pore volumes in the range of 526–2386 m2/g and 0.26–1.16 cm3/g, respectively were prepared by treatment of a nitrogen-rich carbon with KOH (KOH to carbon weight ratio = 1.5) at different temperatures (y) in the range of 550–700 °C. The prepared samples were used to delineate the role of pore sizes and nitrogen content...
Stearic acid (SA) is encapsulated by a water-dispersible graphene functionalized with poly(vinyl alcohol) using an eco-friendly Pickering emulsion route to prepare a novel shape-stabilized phase change composite for thermal energy storage. In the method, the oil phase of melted SA can be easily encapsulated and stabilized by the graphene Pickering stabilizer in an aqueous medium. The subsequent solidification...
Oxygen transfer reactions on carbon surfaces are of great interest for a variety of industries, as well as for the development of new technologies (e.g., NO gas detectors). They are also at the heart of the chemical surface properties and behavior of graphene-based materials. In this study we use quantum chemistry to discover the most probable ground and transition states of reactants, surface intermediates...
Graphene-based composites have been deemed as promising materials in renewable energy-storage applications. Herein, we report a hybrid architecture consisting of layered molybdenum sulfide nanosheets/N-doped graphene (MoS2/NG) synthesized by one-pot hydrothermal method. By adjusting precursor ratios, flower-like MoS2/NG hybrid with nitrogen content of 3.5 at.% on the graphene layers can be obtained...
The effect of desorption purge gas oxygen content on activated carbon performance, specifically irreversible adsorption, was investigated. Beaded activated carbon (BAC) was tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds representing industrially-relevant organic groups. Different concentrations of oxygen (≤5–10,000 ppm) were used in the N2 desorption purge gas...
Nitrogen-doped (N-doped) porous carbon nanofiber webs (CNFWs) have been successfully prepared via one-step carbonization-activation treatment of pre-synthesized polypyrrole (PPy) nanofiber webs (NFWs). In this preparation process, the carbonization of the precursor and further activation with KOH were completed simultaneously. We detailedly investigated the effect of different activation conditions...
Despite its importance, the mechanical behavior of graphene under the impact of projectiles has rarely been studied due to experimental and computational difficulties. Here, we simulated the impact of silica and nickel projectiles with a supersonic initial velocity on graphene. Then we analyzed the impact by using ReaxFF reactive force field method, which is capable of describing the entire system...
A unique isotropic pitch composed of linear chains of polycondensed aromatic molecules was synthesized through the bromination and subsequent dehydrobromination of mixed naphtha-cracked oil (NCO) and quinoline-insoluble free coal tar (CT). Isotropic pitch-based carbon fibers obtained from the co-carbonization of an NCO/CT mixture via bromination and dehydrobromination exhibited an unprecedentedly...
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