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We present different properties of 2D carbon allotropes: α-, β- and γ-graphynes based on Density Functional Theory calculations. Among the set of properties studied there are structural (e.g., cohesive energies, optimum lattice parameters, interatomic distances, pore sizes, planar packing densities and specific surface areas), mechanical (e.g., uniaxial along with homogeneous and heterogeneous biaxial...
We report the extensive investigation of Li and H dynamics in Li6C60 and Li6C60Hy, by combining 7Li and 1H solid state NMR measurements with DC/AC conductivity, in order to evaluate the potential application of these systems for energy-storage purposes. 7Li NMR results show a local motion of Li ions above 200 K in both pristine and hydrogenated compounds, with activation energies of 90–150 meV and...
The mechanical properties of four different families of ordered porous graphene or giant Schwarzites, up to 12,288 atoms per cubic cell, were studied theoretically in order to shed light on the properties of newly synthesized graphene-like foams. It is shown that as the Schwarzite grows in size, the structure becomes flatter and not only more energetically stable, but also more elastically stable,...
Neutron diffraction and synchrotron X-ray diffraction and imaging have been applied to study, in situ, the mechanical response to tensile and bending loading of polygranular Gilsocarbon nuclear grade near-isotropic graphite (grade IM1-24). Digital image correlation of X-ray radiographs and digital volume correlation of tomographs allow measurement of bulk elastic moduli and examination of the heterogeneity...
Hybrid systems formed by carbon nanotubes filled with metal represent a class of nanomaterials with manifold functionality that can find applications in different fields as, for example, magnetic storage and spintronics. Here a detailed and comprehensive study is reported on the magnetic properties of template grown cobalt cluster-filled multiwall carbon nanotube arrays. The temperature and magnetic...
Approach-to-equilibrium molecular dynamics simulations have been used to study thermal transport in nanocrystalline graphene. Nanostructured graphene has been created using an iterative process for grain growth from initial seeds with random crystallographic orientations. The resulting cells have been characterized by the grain size distribution, by the number of atoms in each grain and the number...
A novel three dimensional (3D) printing method is developed to fabricate complex carbon/carbon (C/C) composite components. The C/C composites with the high mechanical performance are achieved by combining the selective laser sintering and the chemical vapor infiltration-thermal treatment process. The C/C composites with a maximum density of 1.5 g/cm3 and bending strength of 100 MPa are obtained. Complex...
High throughput synthesis of atomic layer graphene membrane by chemical vapor deposition (CVD) is one of key technologies to establish industrial applications. Here we report the details of the initial stage of graphene growth on copper substrate by radio frequency (RF) plasma-assisted CVD under low pressure and compare the nucleation rate and the growth rate with conventional thermal CVD. Two-dimensional...
Mechanical behavior of three-dimensional cellular assembly of graphene foam (GF) presented temperature dependent characteristics evaluated at both low temperature and room temperature conditions. Cellular structure of GF comprised of polydimethyl siloxane polymer as a flexible supporting material demonstrated 94% enhancement in the storage modulus as compared to polymer foam alone. Evaluation of frequency...
Hierarchical structure characterized by the decoration of few-layer graphene (FLG) surface with a dense network of carbon nanofibers (CNF) was synthesized by Chemical Vapor Deposition. This hierarchical composite was further used as host matrix for the dispersion of nanodiamonds (ND) to produce a metal-free catalyst for the direct dehydrogenation (DH) process of ethylbenzene (EB) to styrene. The as-synthesized...
A micromechanistic model has been applied to understand the relation between the properties of individual graphite crystals and the properties of polycrystalline graphite. The proposed model accounts for irradiation-induced creep as well as microcracking in both intragranular (parallel to basal planes) and intergranular positions. The two types of cracks were found to have a combined effect on the...
Fibres made from carbon nanotubes (CNTs) have not yet achieved strengths approaching that of individual CNTs. The problem is that load is not effectively transferred between the constituent, discontinuous CNTs. High energy irradiation has shown promise on small CNT bundles, in creating covalent cross-links to enhance load transfer, but cannot sufficiently penetrate real CNT fibres, which typically...
We have revealed that molecular oxygen breaks into carbon nanotubes forming active sites to abstract hydrogen from propane. Various carbonaceous species (carbon defects and debris) on carbon nanotubes were identified and their effects on the oxo-functionalization as well as the catalytic performance in the oxidative dehydrogenation of propane were thoroughly investigated. The results indicate that...
The success of graphene technologies will require the development of safe and cost-effective nano-manufacturing methods. Special safety issues arise for manufacturing routes based on graphite oxide (GO) as an intermediate due to its energetic behavior. This article presents a detailed thermochemical and kinetic study of GO exothermic decomposition designed to identify the conditions and material compositions...
Oxidation is one of the main decomposition mechanisms of fibrous carbon/phenolic ablators employed in thermal protection systems for planetary entry capsules. The oxidation process is driven by two competing mechanisms: diffusion of reactants within the porous medium, and reaction rates at the surface of the fibers. These mechanisms are characterized by the Thiele number. Given that the Thiele number...
Doubts about a two-component structural model of graphene oxide have been raised recently in a paper in Carbon. Here we revisit the arguments presented and show why, contrary to the claims in this recent paper, the evidence is indeed consistent with as-produced graphene oxide consisting of large (micron sized), lightly oxidised, monolayer graphene-like sheets to which are complexed small, highly oxidised,...
The oxidative carbon removal from Cu foils was systematically studied together with the resulting suppression of the graphene flake nucleation during subsequent chemical vapor deposition (CVD). The carbon content was determined by segregating bulk dissolved carbon during a special rapid cooling process towards the surface, where it was detected by x-ray photoelectron spectroscopy. After exposure to...
In this paper, three-dimensional bicontinuous porous graphite (3Dbp-graphite) with well-developed graphite structure is generated by dealloying in metallic melt at 1073 K in the low temperature region for synthesizing graphite. The N2 adsorption–desorption isotherm curves of 3Dbp-graphite show that the porous structure essentially consists of meso–macro pores. Its specific surface area and pore volume...
We used soluble graphene derivatives to fabricate gas barrier coatings on the surface of several industrially relevant commodity polymers. The coatings are prepared using electrochemically exfoliated graphene oxide, featuring both monoatomic thickness and micron-scale lateral size, showing better gas barrier performance as compared to films of commercial graphene products. A 74% decrease of oxygen...
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