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The photoluminescence (PL) quenching of water-soluble graphene oxide (GO) solution was systematically investigated in the presence of transition metal ions. Their PL spectra were analyzed by the Stern–Volmer equation, and the trend of the quenching efficiency was Fe2+>Co2+>Ni2+>Cd2+>Hg2+. The results of the steady-state and time-resolved PL spectra of the GO solution suggested that the...
This letter reports on the extended polymerization occurring in ABC-stacked C70 fullerite, which up to now was thought to occur only in the AB-stacked phase. Frustration effects on ABC close-packing of C70 molecules were believed to prevent extended polymerization based on 2+2 cycloaddition bonds, but here we show that an extended polymeric phase is obtained at 10GPa and 270°C. Its structure, obtained...
Using graphene metamaterial (MM) patterns, the tunable resonant properties of graphene–SiO2/Si (GSiO2Si) structures deposited on flexible polymer substrates have been theoretically investigated in the terahertz regime. This study shows that the tuning mechanism of the GSiO2Si structure mainly depends on dipolar resonance, which is different from the conventional metallic MM structure based on the...
We present results of molecular dynamics simulations of graphene on Cu surfaces. Interactions were modelled with the charge-optimized many-body potential, which gives a reasonable though not flawless description of the graphene–Cu system. The interaction between Cu and complete graphene sheets is characterized by an ‘averaged out’ interaction at a large bonding distance. Many bonding characteristics...
We have prepared pristine graphene and nitrogen-doped graphene on copper foils by chemical vapor deposition. Compared with the pristine graphene, an increased disorder in nitrogen-doped graphene was confirmed by Raman spectra studies. Temperature dependent Hall resistances and magnetoresistances were measured for both samples. The carrier densities can be extracted from the experimental datum. Abrupt...
The thermally decomposed citric acid (TDCA) possesses either excitation-dependent or excitation-independent fluorescence as well as different quantum yields with varying synthesis conditions (i.e. temperature and reaction duration). These photoluminescent (PL) properties were found to be mainly determined by the quantitative competition between the graphene quantum dots (GQDs, average size in the...
Two solar missions are designed to plunge into the solar corona, and respectively get as close as 8.5 and 3 Rs (solar radii) from the Sun’s surface. Heat shields will protect the payloads within their umbra from the thermal radiation and solar winds. We report the high temperature behavior of a pBN coating on a C/C composite. We established thanks to spectral emissivity measurements at high temperature...
Hybrid Nafion membranes are prepared, using various fillers, such as anatase-type TiO2 nanoparticles, graphene oxide (GO) and organo-modified graphene oxide (abbreviated as GOSULF) for water purification applications. Scanning electron microscopy analysis confirms the homogeneous dispersion of the fillers. The photocatalytic properties of the hybrid membranes are evaluated using the azo dye methyl...
We report a binder-free Li-ion battery anode based on a tin (Sn) coated vertical-aligned carbon nanotube (VACNT) array. In this anode, the VACNT array, acting as a robust core matrix to support high theoretical capacity active material Sn, offers large inter-wire spacing for Sn expansion during the lithiation/de-lithiation processes and forms direct conductive pathways for electrons transporting....
Highly microporous carbon spheres for CO2 adsorption were prepared by using a slightly modified one-pot Stöber synthesis in the presence of potassium oxalate. Formaldehyde and resorcinol were used as carbon precursors, ammonia as a catalyst, and potassium oxalate as an activating agent. The resulting potassium salt-containing phenolic resin spheres were simultaneously carbonized and activated at 800°C...
Electrically conductive polycarbonate (PC)/carbon nanotube (CNT) composites were prepared by melt compounding. Well-controlled voids were introduced into the PC/CNT composites by supercritical CO2 foaming technique. The dispersion of CNTs and the cellular morphology of the PC composite foams were characterized with transmission electron microscopy and scanning electron microscopy, respectively. The...
This work highlights the possible use of vertically-aligned multiwall carbon nanotubes (VA-MWCNTs) as bottom electrodes for microelectronics, for example for memory applications. As a proof of concept BiFeO3 (BFO) films were fabricated in-situ deposited on the surface of VA-MWCNTs by RF (radio frequency) magnetron sputtering. For in situ deposition temperature of 400°C and deposition time up to 2h,...
The cycloaddition reaction of carbon dioxide (CO2) with styrene oxide (SO) to produce styrene cyclic carbonate (SC) catalyzed by various imidazolium-based ionic liquids (ILs) in the presence of graphite oxide (GO) was studied under relatively mild conditions. It was revealed that the inherent Brønsted acidic groups of the GO and halide anion of ILs exhibited an excellent synergistic effect in promoting...
A novel “etching-precipitation” method is proposed and developed for the direct synthesis of graphene on dielectric substrates. In this method, graphene precipitates from the Fe–C solid solution film during selective etching of Fe using Cl2 gas. Few- and multi-layer graphene is fabricated directly on quartz glass and SiO2/Si substrates without Fe residue at a growth temperature of 500–650°C, which...
Doping is an important method to modulate the electronic properties of graphene. Among various types of doped graphene, sulfur-doped graphene is expected to have a wider band gap due to the electron-withdrawing character of sulfur. However, it is difficult to dope graphene with S because S atom is much larger than C atom. In this paper, S-doped graphene is synthesized by a simple method with hydrogen...
A wide band gap semiconducting form of graphene can be produced by growing a buckled form of graphene from a SiC(0001¯) surface randomly seeded with nitrogen. In this work, we show that the disorder observed in this form of graphene can be substantially reduced by pre-patterning the nitrogen seeded SiC surface into trenches. The result of the patterning is highly improved film thickness variations,...
Electrochemically active diamond-like carbon (DLC) electrodes featuring high specific surface area have been prepared by plasma-enhanced chemical vapour deposition (CVD) onto densely packed forests of vertically aligned multiwall carbon nanotubes (VACNTs). The DLC:VACNT composite film exhibits a complex topography with web like features and ridges generated by partial coalescence of the DLC over the...
Enhancing the electrical conductivity and reliability of graphene electrodes is critical for the practical realization of graphene-based electronics, since these factors influence the electrical performance of devices. To achieve such improvements in graphene electrodes requires additional processes such as doping and surface treatments, which inevitably complicate device fabrication. Here, we introduce...
Morphology-controllable carbon nanocoils (CNCs) are synthesized by thermal chemical vapor deposition using Ni nanoparticle as catalyst prepared by spray-coating method. It is found that, with the increase of number of spray-coating times, the helicity of CNCs increases whereas the average line diameter and coil pitch decrease. Additionally, infrequent Y-junction CNCs and plait-like CNCs are found...
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