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Here, we present a facile technique to design self-supported 3D N-doped graphene foam (NGF) via simply annealing in chemical vapor deposition furnace which used powder metallurgy nickel template and melamine as both carbon and nitrogen source. The NGF possesses highly conductive and interconnected mesoporous network. Particularly nitrogen-doping provided strong polysulfide immobilization ability,...
Controlled nanotwinning is an effective way to enhance the mechanical properties of materials. Recent discovery of nanotwinned diamond converted from carbon nano-onions with high-density defects reveals that the presence of nanotwinned structures can increase the hardness of the product to exceed that of natural diamond by a surprisingly large margin. To understand the mechanism of nanotwinning, the...
Spinel ZnMn2O4 is considered as a potentially high-capacity anode material for Li-ion batteries. However, its low conductivity causes poor rate capability and insufficient cyclability, thus turning into a challenge for battery applications. Hybrid inorganic/ordered mesoporous carbon (CMK-3) nanostructure represents a promising material platform for next-generation energy storage due to the presence...
Boron carbon oxynitride (BCNO) phosphors can exhibit remarkable tunable emission colors and greenish persistent luminescence without the assistant of rare-earth ion dopants. However, the photoluminescent and persistent luminescence (PL) mechanisms of BCNO are still not fully understood. In this work, we attempt to reveal distinct photoluminescent and PL mechanism of BCNO based on the first-principles...
We demonstrate growth of single-layer graphene (SLG) on hexagonal boron nitride (h-BN) by molecular beam epitaxy (MBE), only limited in area by the finite size of the h-BN flakes. Using atomic force microscopy and micro-Raman spectroscopy, we show that for growth over a wide range of temperatures (500 °C – 1000 °C) the deposited carbon atoms spill off the edge of the h-BN flakes. We attribute this...
Reduced graphene oxide (RGO) was decorated with well dispersed ZnO nanocrystals with narrow grain size distribution by a facile in-situ growth strategy. Zinc ions were absorbed on graphene oxide (GO) sheets through interaction with functional groups in absolute ethanol. After adding hydroxyl ions, the precursor of ZnO formed on GO sheets and crystallized after thermal treatment during which the GO...
The graphene quantum dots (GQDs) are attractive nanomaterials with excellent optical and optoelectronic properties. However, the clear photoluminescence (PL) was difficult to be investigated due to the complicated structures of the reported GQDs. In this work, four kinds of GQDs were synthesized by organic methods with certain chemical structures. The PL mechanism of the GQDs was investigated by ultrafast...
A cylindrical phase change energy storage system was modeled numerically using the finite element method. The model system was composed of a cylindrical container into the center of which is inserted concentrically a copper pipe carrying hot water. Either copper fins or compressed expanded natural graphite (CENG) were placed as heat-conducting fillers between the container and the pipe for comparison...
Activated carbons (ACs) were prepared by CO 2 activation using depleted fullerene soot as precursor. The structure of the ACs was investigated by TEM, XRD, and nitrogen adsorption. Their electrochemical properties in electrochemical capacitors were tested by cyclic voltammetry (CV) and galvanostatic charge/discharge methods in a three-electrode cell. Activation temperature and time were proved...
Natural graphite was leached under microwave irradiation by acid mixtures containing HCl (12M) and HNO 3 (16M). It was found that the purification efficiency was affected by microwave power, reaction pressure, reaction time and the acid ratio. The carbon content of the graphite increased from 95.84% to 99. 43% under optimized leaching conditions with an acid volume ratio of 1:1, pressure of...
Three-dimensional flowerlike nitrogen-doped carbons (NCs) have been prepared by copyrolysis of solid ferrocene and melamine at 500–700°C. X-ray photoelectron spectroscopy N1s spectra show three kinds of C–N bonding patterns: pyridinic-, pyrrolic-, and graphitic-type nitrogen species, and the atomic percentage of doping nitrogen can be adjusted between 0.67% and 4.62% by controlling reaction temperature...
The preparation of self-assembled ordered mesoporous carbons (SA-OMCs) using a soft template method has many advantages, such as low cost, ease of preparation and control. In this paper, we review the development periods, the basic principles and preparation procedures with an emphasis on the control of morphology and multi-level pore structure of OMCs based on SA-OMCs. We suggest that further research...
A method is presented to tailor the lateral size of graphene oxide (GO) in the range of 10–100nm and simultaneously tailor its edge structure by oxidation with periodic acid in a one-pot process. The obtained GO nanosheets are photoluminescent and exhibit lateral size-dependent behavior. The emission wavelength could be tuned from 550 to 470nm by decreasing the lateral size. The fluorescence of GO...
A 4-direction carbon/carbon composite was produced. The ablation of 4-direction carbon/carbon composite nozzles was investigated in the combustion environment of a solid rocket motor. The ablation surface and microstructure were examined by scanning electron microscopy and the ablation mechanism was also studied. The results show that the nozzle recession rate increases with the increasing mass flow...
A stable aqueous dispersion of reduced graphene oxide (rGO) has been prepared by the chemical reduction of graphene oxide with the use of benzylamine as a reducing and stabilizing agent. Raman spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the resulting rGO. The rGO could be decorated with Ag nanoparticles (AgNPs) by direct adsorption of preformed, negatively-charged...
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