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We investigate the aggregation, diffusion, and resulting electrochemical behavior of ionic liquids inside carbon electrodes with complex pore architectures and surface chemistries. Carbide-derived carbons (CDCs) with bimodal porosities and defunctionalized or oxidized electrode surfaces served as model electrode materials. Our goal was to obtain a fundamental understanding of room-temperature ionic...
We develop a simple one-step growth method to obtain a novel kind of tree-like carbon nano composite structure on a 4″ stainless steel substrate, which is a nano graphene-carbon nanotube tree (GCT). The structures are synthesized by using a plasma enhanced chemical vapor deposition method. The GCT consists of few-layer graphenes (FLG) epitaxially growing from a carbon nanotube (CNT) and they can grow...
For the first time, ultrathin boron bridged graphene oxide (GO) membranes have been successfully constructed on the modified microporous hollow fiber substrates using borates as the cross-linker. Nanochannels within GO layers can be molecularly engineered by manipulating the annealing process and the chemistry of boron bridges. GO framework composite membranes with proper charge properties and size...
The atomic edge, excellent conductivity, stable chemical and mechanical properties make graphene a good candidate for the scanning tunneling microscopy (STM) tip. Here, a one-step growth method is used to fabricate graphene STM tips. The graphene was directly grown on a sharp tungsten tip vertically by using microwave plasma enhanced chemical vapor deposition method without any catalyst. The high...
A concurrently high beam current and high current density carbon nanotube (CNT) cold cathode electron gun is herein developed. A radial electron source has been realized, formed from CNTs synthesized directly on the side walls of a stainless steel truncated-cone electron gun. Experimental results evidenced a 35 kV/50 mA electron beam can achieve a beam transparency of nearly 100% through the use of...
Recent experiments have shown that electric double-layer capacitors utilizing electrodes consisting of graphene edge plane exhibit higher capacitance than graphene basal plane. However, theoretical understanding of this capacitance enhancement is still limited. Here we applied a self-consistent joint density functional theory calculation on the electrode/electrolyte interface and found that the capacitance...
Fine particulate matter (PM 2.5) is the principal instigators of adverse health events, yet gaps still remain in understanding the mechanism mediating its toxic response. Similar to nanoparticles, PM 2.5, with large surface area to volume ratio, can absorb multipollutants in air, displaying toxicity profiles that are very different from those of coarse particles of the same composition. One particularly...
Over the past decade, reports of graphene-based devices have increased exponentially due to the superior characteristics and unique advantages that graphene introduces. However, the cost-effective growth and patterning of graphene is always a challenge for large-scale graphene-based device applications. Here we report a universal method based on one-step laser scribing technology for quick synthesis...
Carbon is a versatile element that has allotropes with both sp2 (graphene) and sp3 (diamond) bonding. However, none of the allotropes can be used as light-absorber materials in solar cells due to either too large or too small band gap. Here, we propose a novel concept that enables a tunable band gap of carbon phases with sp2 carbon atoms within a sp3 carbon structure. The tunability is due to the...
Prolonged therapeutic action over an extended period of time on single dose is vital in designing an ideal drug delivery system. Nanoparticle-based vehicles for drug delivery serves as an ideal technology, however, utilization of them remains controversial due to potential safety concerns and transient drug retention. Nanodiamonds (NDs), with excellent biocompatibility and diversity of potential conjugates,...
The energy storage mechanism of N-doped carbons with low apparent specific surface areas (Brunauer–Emmett–Teller specific surface area determined by N2 adsorption) has puzzled the researchers in the supercapacitor field in recent years. In order to explore this scientific problem, such carbon materials were prepared through pyrolysis of N-rich polymers such as melamine formaldehyde resin and polyaniline...
In an early report, some of us have demonstrated that graphene-sheet films prepared by electrophoretic deposition (EPD) method have great potential as high-performance field emission cathode. We report that the field emission performance from such graphene-sheet films may be enhanced. We have investigated the correlation between topographic structures and local field emission characteristics of graphene-sheet...
Vertical few-layer graphene (FLG) sheets have potential applications as field emitters and super capacitors. However, it remains a challenge to controllably grow FLG with vertical and parallel orientations. We intentionally designed the substrate surface structure to manipulate the distribution of the plasma sheath and induce the direction of the built-in electric field to guide the growth direction...
Carbon nanotubes (CNTs) were synthesized on carbon fibers by a modified thermal chemical vapor deposition (CVD) method. The fibers were first treated at a temperature of 973K and then treated by a mixture of sulfur acid and nitric acid with a volume ratio of 1:3 to improve the dispersion of catalyst precursor (Fe (NO 3 ) 3 ·9H 2 O) on the surface before impregnation with a...
Ordered mesoporous carbons were prepared by pyrolysis of polymer blends, which were formed by the organic–organic self-assembly of resorcinol–formaldehyde pre-polymers and tri-block copolymers under acidic conditions. The tri-block copolymer mixtures of F127 and P123 were used as structure-directing agents. The samples were characterized by X-ray diffraction, transmission electron microscopy and nitrogen...
An oxygen-assisted field emission treatment is introduced for improving field emission uniformity of carbon nanotube (CNT) pixel arrays. Oxygen gas is added during the field emission process, and the uniformity of both emission area and brightness of a CNT pixel array are dramatically improved by 83% and 90%, respectively, without reducing emission stability. The underlying physical mechanism for...
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