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The scalable, low-cost fabrication of high quality graphene is a subject of intense research. Here, a novel method to synthesize uniform and large area graphene films directly on various high-temperature resistant insulating substrates such as SiO2/Si, Al2O3 and quartz glass by low pressure chemical vapor deposition (LP-CVD) using a mild oxidant (CO2) and a carbon source (CH4), without the aid of...
Porous C/Ag nanohybrids were one type of emerging and promising alternative oxygen reduction catalysts for Pt, which was crucial to energy conversion and storage devices. Herein, a template-free, sustainable and in-situ method was employed for preparing N-doped hollow carbon tube @ hierarchically porous carbon supporting homogeneous Ag nanoparticles (HCT@HPC@AgNPs) by one-pot carbonization with the...
Fluorinated graphene quantum dots (FGQDs) have distinctive charge distribution in structure and unique chemical bonds in composition, corresponding to novel performance different from common quantum dots. However, their synthesis is a challenge due to chemically inert CF bonds and hydrophobic nature, and the fluorine influence on FGQDs remains scarce and to be studied. Herein, we first design a gradient...
This work discusses and compares two proposed practical approaches for realizing graphene-based reconfigurable terahertz metamaterials, namely: graphene-only plasmonic structures, and graphene/metal hybrid structures. From rigorous theoretical analysis, full-wave electromagnetic numerical simulations, as well as supporting experiments, several reconfigurable structures are analyzed and compared in...
Previous experiment of shock compression of the mixture of carbon black and tetracyanoethylene produced clear evidence of a new structural unidentified cubic carbon phase. In this letter, we confirmed that the previously proposed C20-sc and its modifications are more proper than recently suggested BC12 for explaining such a novel simple cubic carbon sample. Most of the X-ray diffraction peaks from...
The electron transfer between a carbon electrode and hemoglobin in solution is known to be a slow and difficult process, likely due to the difficulty in accessing the redox active heme groups of hemoglobin. Literature data are inconsistent regarding electrochemical activity of hemoglobin on carbon electrodes and whether carbon-oxygen-containing surface functional groups enhance or inhibit the electroactivity...
Hydrogenated amorphous carbon thin films (a:C-H) are very promising materials for numerous applications. The growing of relevance of a:C-H is mainly due to the long-term stability of their outstanding properties. For improving their performances, a full understanding of their local chemistry is highly required. Fifteen years ago, electron energy-loss spectroscopy (EELS), developed in a transmission...
MWCNT encapsulated by highly porous carbon, also called as Tube-in-Tube carbon (TTC), obtained from hard template assisted synthesis method acts as an efficient host for Se cathode in Li-Se battery. One dimensional nano structured TTC with a high pore volume of 2.167 cc/g and an appreciable surface area of 1131 m2/g is capable of accommodating as high as 70 wt% Se. Notably, 50 wt% Se@TTC delivers...
A green pyrolysis approach to prepare ultra-small nitrogen and sulfur-co-doped carbon dots (N,S-C-dots, QY reaches 55.7%) with precursors citric acid (CA) as carbon source and N-acetyl-l-cysteine as N and S dopant has been explored. The optical properties and the origin of photoluminescence (PL) have been investigated at length. The mixed excitation independence character (200 ≤ λex ≤ 380 nm) and...
The morphology of Si-C soot synthesized by a DC arc discharge in a helium atmosphere at a pressure of 25 torr with different concentrations of Si was studied experimentally. An increase in silicon concentration in the sputtered electrode lead to the formation of graphene structures with 1–7 graphene layers, patterned with nanoparticles of SiC. When the concentration of Si in the dispersed electrode...
The influence of particle size on the growth of nanopores arising from gasification of a South African coal-char was investigated using small angle X-ray scattering. Three different char sizes (75 μm, 2 and 20 mm) were gasified between 800 and 1000 °C to specific conversions up to 50% and the pore development during CO2 and steam gasification was compared. For the CO2 gasified chars studied here,...
Graphene-based resistive random access memory devices is a promising non-volatile memory technology that combines low operation voltage and power, extremely fast write/erase speeds, excellent reliability and storage capacity of RRAM with low-cost, large area and flexibility of carbon-based technologies. However, low-cost single-step synthesis of high-quality graphene remains a challenge. In this paper,...
Chitosan, glucosamine, a glucose-melamine mixture, a glucose polyvinylpyrrolidone mixture, and a glucose poly(vinylpyrrolidone-co-vinylimidazole) mixture are examined in a hydrothermal carbonization and calcining process to investigate effects of nitrogen additives on incorporation of nitrogen into the carbon products and the effects of such additives on morphology and porosity. The resulting calcined...
Conducting carbon is added to electrodes of lithium ion batteries (LIBs) to provide electrical conductivity. Because this carbon does not contribute to capacity, there is a drive towards decreasing its content with a goal of lowering the mass of the electrode. Reduced graphene oxide (RGO) has a high electrical conductivity, and is a potential alternative to traditionally used conductive carbon black...
Reproducible and in-depth studies of the electrochemical graphite intercalation and oxidation processes were carried out with the use of an electrochemical Tee-cell setup. The electrochemical method allowed simpler and greater controllability over the level of oxidation/functionalization, relative to the commonly employed chemical oxidation approach (e.g. the modified Hummers method). Extensive characterization...
Since it was discovered, synthesizing large area graphene sheets by chemical or epitaxial methods is the conventional method for the application of graphene's outstanding properties. Unfortunately, CVD grown graphene is polycrystalline in nature with grain boundaries (GBs) unlike exfoliated single crystal graphene flakes. These GBs are known as the main source of degrading mechanical, chemical and...
MoS2–graphene oxide (GO) hybrids of different compositions were prepared in the form of a few micron thick flexible paper by a simple ambient condition evaporation of a mixture of colloidal dispersions of ammoniated MoS2 and GO. These, on thermal reduction at 400 °C, convert to MoS2–reduced graphene oxide (rGO) hybrids, retaining the macroscopic paper-like structure. These hybrids act as efficient...
The present work explores new methodology of fabricating the polymer nanocomposite with improved interlaminar, dynamic and micro mechanical properties. Varying amount of carbon nanofibers (CNF) were filled into the glass fiber/unsaturated polyester composite using filtering membrane vacuum-assisted method. Microporous nylon membrane was used to improve the dispersion of CNF in the lamination panels...
Covalent functionalization of single-walled carbon nanotubes typically leads to an intensity increase of the defect-induced Raman mode (D mode). A large intensity ratio of the D and G modes (D/G ratio) is therefore often used as evidence for a successful functionalization. Here, we discuss the effect of the D-mode resonance on the D/G ratio and compare pristine and covalently functionalized nanotubes...
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