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The previous studies on SnO2 as electrode materials convey a message that the inevitable pulverization of SnO2 particles can be resolved by carbon-based materials. Since graphene has also proved effective for the harmful decrepitation of the particles with an advantage of electronic conductivity, wrapping SnO2 by sufficient amount of graphene seems to be an answer to enhancing its cycle life. On the...
We demonstrate an electrochemical method – which we term oxidative decoupling transfer (ODT) – for transferring chemical vapor deposited graphene from physically deposited copper catalyst layers. This copper oxidation-based transfer technique is generally applicable to copper surfaces, and is particularly suitable where the copper is adhered to a substrate such as oxidized silicon. Graphene devices...
Individual graphene layers in a multilayer graphene sample contribute their own edges. The edge of a graphene layer laid on an n layer graphene (nLG) is a building block for the edges of multilayer graphenes. We found that the D band observed from the edge of the top graphene layer laid on the nLG exhibits an identical line shape to that of disordered (n+1)LG. Based on the spectral features of the...
A Ni(OH)2-graphene hybrid with a three dimensional (3D) interconnected graphene network was prepared by a simple one-pot hydrothermal method. The 3D structure constructed of flexible and planar graphene sheets (GS) forms an effective electron transfer network and provides a continuous pore structure for ion transport. Moreover, this structure avoids the aggregation of GS and Ni(OH)2, resulting in...
Thermal transport in graphene–polymer nanocomposite is complicated and has not been well understood. The interfacial thermal transport between graphene nanofiller and polymer matrix is expected to play a key role in controlling the overall thermal performance of graphene–polymer nanocomposite. In this work, we investigated the thermal transport across graphene–polymer interfaces functionalized with...
Polyimide(PI)-based carbon fibers with different properties were prepared by carbonization of PI fibers at 800°C, followed by heat treatment from 800 to 2800°C. The effect of heat treatment temperature (HTT) on elemental composition, surface morphology, mechanical properties, and the thermal and electrical conductivities of PI-based carbon fibers were investigated by elemental analysis, SEM, HRTEM,...
A series of nitrogen-doped porous carbons are prepared from nitrogen-containing zeolitic imidazolate framework (ZIF) and additional carbon sources (including melamin, urea, xylitol and sucrose) via co-carbonization at T=950°C. Results indicate that macromolecular carbon sources, say, sucrose, can effectively protect the nitrogen loss from ZIF backbone owing to the pre-melting and polymerization of...
Understanding the atomistic mechanisms of tensile failure in carbon fibers is important for fiber manufacturing and applications. Here we design structural faults with atomistic details, pertaining to polyacrylonitrile (PAN) derived fibers, and probe them using large-scale molecular dynamics simulations to uncover trends and gain insight into the effect of local structure on the strength of the basic...
A nitrogen-doped carbon layer coated thermally exfoliated graphene (NC-TEG) is prepared by in-situ polymerization of p-phenylene diamine (PD) with thermally exfoliated graphene (TEG) and subsequent high temperature pyrolysis (600°C for 1h in argon gas environment). Fourier transfer infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy confirm the formation of poly-(p-phenylene...
Carbon papers (CPs) with high electrical conductivities and gas permeabilities have been historically used as gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs). CPs with high electrical conductivities are fabricated by the high temperature carbonization of a thermosetting resin, which acts as a binder and makes the CPs brittle to bending. Herein, we report the fabrication...
Luminescent nanomaterials have been explored intensively to serve as biosensors and bioimaging agents and for other biomedical bioapplications. Among them, carbon dots (C-dots) as a new type of biocompatible carbon-based nanomaterials have attracted tremendous attention because of their low toxicity, excellent water solubility, ease of synthesis and functionalization, and outstanding photostability...
Nitrogen-doped carbon materials are known to exhibit good electrocatalytic activity for the oxygen reduction reaction (ORR). However, the structure of the active site for the ORR remains unknown. In this work, a series of nitrogen-doped carbon nanospheres (N-CNSs) were successfully prepared by using porcine blood protein as specific nitrogen source at different pyrolysis temperatures. The results...
In this work, we describe a new type of activation method of carbon materials using pressure swing of CO2. The porosity development markedly depends on the pressure swinging frequency. The porous carbon obtained from pressure-swing activation shows an additional porosity development without pitting corrosion on the surface, which occurs on CO2 activation without pressure-swing. This phenomenon is...
This paper presents the results from the investigation of the influence of the chlorination temperature, the carbide crystal structure, the Cr/C ratio and physicochemical properties of CrCl3 on the morphology, nanostructure, textural properties and electrochemical performance of CDCs. Electron microscopy and its analytical associated techniques reveal that these carbons, mainly composed by disordered...
High energy light-ion (3.8MeV He) bombardment is used to introduce lattice defects in a 3-dimensional (3D) interconnected network of graphene aerogels (GAs). When these materials are used as anodes for lithium ion batteries, we observe improved percentage reversible capacity and cycle stability compared to those without ion-beam treatment. Furthermore, all ion-beam treated 3D graphene samples exhibit...
The effects of graphite oxide (GO) additions on the oxygen reduction reaction (ORR) activity of carbon alloy catalysts were examined in order to develop high performance cathode catalysts for polymer electrolyte fuel cell. Different amounts of GO were mixed with a carbon alloy precursor consisting of phenolic resin and phthalocyanine iron, followed by carbonization at 800°C. Thermogravimetry revealed...
Nanoparticles (NPs) of Pt, Ni or NiO, deposited on few-layered graphene using pulsed laser ablation catalyze the in-situ formation of graphitic shells from graphene. These shells encapsulate the NPs as their cores. High substrate temperature (>450°C) was necessary for this unique transformation. Size distribution of the core–shell NPs could be adjusted by varying the deposition parameters. The...
Porous carbons (PCs) for super capacitors were prepared from coal tar pitch by a one-step microwave-assisted KOH activation with low KOH consumption. The surface area of the PC (PC2−M) made at a KOH/pitch mass ratio of 2 with microwave heating for 30min reaches 1786m2/g. The electrochemical performance of the PC electrode for super capacitors was evaluated in different electrolytes including KOH,...
We investigate the mechanical properties of polycrystalline graphene deforming under uniaxial tension by using molecular dynamics simulations, focusing on the effects of grain size, temperature and strain rate. It is found that polycrystalline graphene with smaller grain size shows a larger drop of Young’s modulus and fracture strength. For the polycrystalline graphene with grain size of 7.5nm, the...
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