نتایج جستجو برای: ribbon carbon doping
تعداد نتایج: 309099 فیلتر نتایج به سال:
Interaction between Nitrogen and Sulfur in Co-Doped Graphene and Synergetic Effect in Supercapacitor
The co-doping of graphene with nitrogen and sulfur was investigated aiming at understanding their interactions with the presence of oxygen in graphene. The co-doped graphene (NS-G) was synthesized via a one-pot hydrothermal route using graphene oxide as starting material and L-cysteine, an amino acid containing both N and S, as the doping agent. The obtained NS-G with a three-dimensional hierar...
PURPOSE Photoreceptor ribbon synapses translate light-dependent changes of membrane potential into graded transmitter release over several orders of magnitude in intensity. A specialized organelle at the active zone--the synaptic ribbon--is a key player in this process, and it is well known that the ribbon undergoes illumination and thus activity-dependent structural changes. However, the molec...
The authors present a method for obtaining graphitized carbon on GaAs 100 surfaces. Carbon-doped GaAs is grown by molecular beam epitaxy before controlled thermal etching within the growth chamber. An AlAs layer beneath the carbon-doped GaAs acts as a thermal etch stop. As the GaAs is etched away, the carbon dopant atoms remain on the surface due to their low vapor pressure. The total number of...
Nanoporous graphitic carbon membranes with defined chemical composition and pore architecture are novel nanomaterials that are actively pursued. Compared with easy-to-make porous carbon powders that dominate the porous carbon research and applications in energy generation/conversion and environmental remediation, porous carbon membranes are synthetically more challenging though rather appealing...
Breaking the electron delocalization of sp(2) carbon materials by heteroatom doping is a practical strategy to produce metal-free electrocatalysts of oxygen reduction reaction (ORR) for fuel cells. Whether carbon nanotubes (CNTs) can be efficiently tuned into ORR electrocatalysts only by intrinsic defects rather than heteroatom doping has not been well studied yet in experiment and theory. Here...
A central result in the space geometry of closed twisted ribbons is Călugăreanu’s theorem (also known as White’s formula, or the Călugăreanu-White-Fuller theorem). This enables the integer linking number of the two edges of the ribbon to be written as the sum of the ribbon twist (the rate of rotation of the ribbon about its axis) and its writhe. We show that twice the twist is the average, over...
Carbon nanotubes, carbon nanocones, and graphene nanoribbons are carbon-based nanomaterials, and their electronic and field emission properties can be altered by either electron donors or electron acceptors. Among both donors and accepters, nitrogen and boron atoms are typical substitutional dopants for carbon materials. The contribution of this paper mainly provides a comprehensive overview of...
We introduce the notion of a half-ribbon Hopf algebra, which is a Hopf algebra H along with a distinguished element t ∈ H such that (H, R,C) is a ribbon Hopf algebra, where R = (t ⊗ t)∆(t) and C = t. The element t is closely related to the topological ‘half-twist’, which twists a ribbon by 180 degrees. We construct a functor from a topological category of ribbons with half-twists to the categor...
We have shown that close to stoichiometry RF PECVD amorphous silicon carbon alloys deposited under silane starving plasma conditions exhibit a tendency towards c-SiC chemical order. Motivated by this trend, we further explore the e ect of increasing RF power and H2 dilution of the gaseous mixtures, aiming to obtain the amorphous counterpart of c-SiC by the RF-PECVD technique. Doping experiments...
First principles methods are used to study N doping of diamondlike amorphous carbon. A structural model containing 216 atoms is introduced, whose properties are in agreement with the available experimental data. The topological and electronic properties for different N doping concentrations are investigated. We find that N occurring in tetrahedral sites or chains of an even number of p bonded s...
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