Search results for "graphene nanoribbons"

A stable path to ferromagnetic hydrogenated graphene growth

2014

In this paper, we propose a practical way to stabilize half-hydrogenated graphene (graphone). We show that the dipole moments induced by an hexagonal-boron nitride (h-BN) substrate on graphene stabilize the hydrogen atoms on one sublattice of the graphene layer and suppress the migration of the absorbed hydrogen atoms. Based upon first principle spin polarized density of states (DOS) calculations, we show that the half hydrogenated graphene (graphone) obtained in different graphene-h-BN heterostructures exhibits a half metallic state. We propose to use this new exotic material for spin valve and other spintronics devices and applications.

Dimensional Confinement in Carbon-based Structures - From 3D to 1D

2017

We present an overview of charge transport in selected one-, two- and three-dimensional carbon-based materials with exciting properties. The systems are atomically defined bottom-up synthesized graphene nanoribbons, doped graphene and turbostratic graphene micro-disks, where up to 100 graphene layers are rotationally stacked. For turbostratic graphene we show how this system lends itself to spintronic applications. This follows from the inner graphene layers where charge carriers are protected and thus highly mobile. Doped graphene and graphene nanoribbons offer the possibility to tailor the electronic properties of graphene either by introducing heteroatoms or by confining the system geome…

The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing

2015

In this paper, we performed synthesis of graphene thin films by rapid thermal annealing (RTA) of thin nickel copper (Ni/Cu) layers deposited on spectroscopic graphite as a carbon source. Furthermore, we investigated the effect of annealing temperature and annealing time on formation and quality of synthesized graphene films. Raman spectroscopy study showed that annealing at lower temperatures results in formation of monolayer graphene films, while annealing at higher temperatures results in formation of multilayer graphene films. We used Raman mapping to determine the distribution of graphene sheets. Surface morphology of graphene thin films was investigated by atomic force microscopy and s…

Limits of stability in supported graphene nanoribbons subject to bending

2016

Graphene nanoribbons are prone to in-plane bending even when supported on flat substrates. However, the amount of bending that ribbons can stably withstand remains poorly known. Here, by using molecular dynamics simulations, we study the stability limits of 0.5-1.9 nm wide armchair and zigzag graphene nanoribbons subject to bending. We observe that the limits for maximum stable curvatures are below ~10 deg/nm, in case the bending is externally forced and the limit is caused by buckling instability. Furthermore, it turns out that the limits for maximum stable curvatures are also below ~10 deg/nm, in case the bending is not forced and the limit arises only from the corrugated potential energy…

Optical and electronic properties of graphene nanoribbons upon adsorption of ligand-protected aluminum clusters

2014

We have carried out first-principles calculations to investigate how the electronic and optical features of graphene nanoribbons are affected by the presence of atomic clusters. Aluminum clusters of different sizes and stabilized by organic ligands were deposited on graphene nanoribbons from which the energetic features of the adsorption plus electronic structure were treated within density-functional theory. Our results point out that, depending on their size and structure shape, the clusters perturb distinctively the electronic properties of the ribbons. We suggest that such selective response can be measured through optical means revealing that graphene nanoribbons can work as an efficie…

Electroburning of few-layer graphene flakes, epitaxial graphene, and turbostratic graphene discs in air and under vacuum

2015

Graphene-based electrodes are very promising for molecular electronics and spintronics. Here we report a systematic characterization of the electroburning (EB) process, leading to the formation of nanometer-spaced gaps, on different types of few-layer graphene (namely mechanically exfoliated graphene on SiO2, graphene epitaxially grown on the C-face of SiC and turbostratic graphene discs deposited on SiO2) under air and vacuum conditions. The EB process is found to depend on both the graphene type and on the ambient conditions. For the mechanically exfoliated graphene, performing EB under vacuum leads to a higher yield of nanometer-gap formation than working in air. Conversely, for graphene…

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…