Search results for "Nanoribbons"

Composites of Graphene with Large Aromatic Molecules

2009

Preparation of Graphene Nanoribbons (GNRs) as an Electronic Component with the Multi-walled Carbon Nanotubes (MWCNTs)

2015

Abstract Carbon nanotubes (CNTs) have a well-defined nanostructure to exhibit high electrical conductivity and chemical stability, and have been used as an advanced material to make electrodes of super-capacitor. Graphene nanoribbons (GNRs), as manufactured by unzipping the CNTs, have more flexible adjustable electrical properties than CNTs, and are regarded an even more promising material for super-capacitor electrodes. This paper presented a series of attempts to prepare GNRs by chemically treating multi-walled carbon nanotubes (MWCNTs); this is, an Oxidation-Reduction method was tried to make GNRs by unzipping MWCNTs longitudinally. Efforts were made in various trials to find conditions …

Curvature in graphene nanoribbons generates temporally and spatially focused electric currents

2015

Today graphene nanoribbons and other graphene-based nanostructures can be synthesized with atomic precision. But while investigations have concentrated on straight graphene ribbons of fixed crystal orientation, ribbons with intrinsic curvature have remained mainly unexplored. Here, we investigate electronic transport in intrinsically curved graphene nanoribbons coupled to straight leads using two computational approaches. Stationary approach shows how transport gaps are affected both by the straight leads and by the degree of edge asymmetry in the curved ribbons. An advanced time-dependent approach shows that behind the façade of calm stationary transport the currents run violently: curvatu…

General Approach to the Description of Fundamental Properties of Disordered Nanosized Media

2017

Physics of non-regular nanosystems is a branch of physics dealing with nanoagents – nanoparticles when non-regular nanosized morphological characteristics predetermine the nature and essence of physical phenomenon (nanophenomenon). In particular, multiple technological interfaces of nanoparticles with morphologically regular systems imply a creation of micro- or mesostructures with essential nanodimensional effects (e.g. in various schemes of functionalization of nanocarbon systems, viz. carbon nanotubes (CNTs), graphene nanoribbons (GNRs), graphene nanoflakes (GNFs), carbon-based nanoaerogels and nanofoams, etc.). However, classes of nanomaterials, in addition to nanocarbon systems, can be…

Optical Imaging and Spectroscopy of Atomically Precise Armchair Graphene Nanoribbons

2019

We report the optical imaging and absorption spectroscopy on atomically precise armchair graphene nanoribbons (GNRs) on insulating fused silica substrates. This is achieved by controlling light polarization on macroscopically aligned GNRs which greatly enhances the optical contrast of the submonolayer GNRs on the insulating substrates. We measure the linear absorption spectra of 7-armchair and 9-armchair GNRs in this study, and the experimental data agree qualitatively with ab inito calculation results. The polarization spectroscopy technique enables an unambiguous optical identification of GNRs and provides a rapid tool to characterize the transferred film over a large area.

Exploring the graphene edges with coherent electron focusing

2010

We study theoretically the coherent electron focusing in graphene nanoribbons. Using semiclassical and numerical tight binding calculations we show that perfect armchair edges give rise to equidistant peaks in the focusing spectrum. In the case of zigzag edges at low magnetic fields one can also observe focusing peaks but with increasing magnetic field a more complex interference structure emerges in the spectrum. This difference in the spectra can be observed even if the zigzag edge undergoes structural reconstruction. Therefore transverse electron focusing can help in the identification and characterisation of the edge structure of graphene samples.

Syntheses and Characterizations of Functional Polycyclic Aromatic Hydrocarbons and Graphene Nanoribbons

2020

In contrast to zero-bandgap graphene, nanostructures of graphene, such as graphene quantum dots (GQDs) and graphene nanoribbons (GNRs) have open bandgaps due to the quantum confinement effect, and are thus highly interesting for semiconductor applications, for example in nanoelectronics and optoelectronics. While conventional methods cannot provide GQDs and GNRs with chemically precise structures, large polycyclic aromatic hydrocarbon (PAH) molecules can be regarded as atomically precise GQDs. Moreover, extension of the PAH synthesis can lead to GNRs with well-defined chemical structures. In this account, we summarize our recent achievements in our synthetic exploration of PAHs and GNRs wit…

Certain doping concentrations caused half-metallic graphene

2017

This work is supported by National Natural Science Foundation of China (Grant No. 21173096).

Bottom-Up, On-Surface-Synthesized Armchair Graphene Nanoribbons for Ultra-High-Power Micro-Supercapacitors

2020

Bottom-up-synthesized graphene nanoribbons (GNRs) with excellent electronic properties are promising materials for energy storage systems. Herein, we report bottom-up-synthesized GNR films employed as electrode materials for micro-supercapacitors (MSCs). The micro-device delivers an excellent volumetric capacitance and an ultra-high power density. The electrochemical performance of MSCs could be correlated with the charge carrier mobility within the differently employed GNRs, as determined by pump–probe terahertz spectroscopy studies.

Electronic structure trends of Möbius graphene nanoribbons from minimal-cell simulations

2014

Investigating topological effects in materials requires often the modeling of material systems as a whole. Such modeling restricts system sizes, and makes it hard to extract systematic trends. Here, we investigate the effect of M\"obius topology in the electronic structures of armchair graphene nanoribbons. Using density-functional tight-binding method and minimum-cell simulations through revised periodic boundary conditions, we extract electronic trends merely by changing cells' symmetry operations and respective quantum number samplings. It turns out that for a minimum cell calculation, once geometric and magnetic contributions are ignored, the effect of the global topology is unexpectedl…