Functionalized Graphdiyne Nanowires: On-Surface Synthesis and Assessment of Band Structure, Flexibility, and Information Storage Potential (original) (raw)
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Synthesis of Extended Graphdiyne Wires by Vicinal Surface Templating
Nano Letters, 2014
Surface-assisted covalent synthesis currently evolves into an important approach for the fabrication of functional nanostructures at interfaces. Here, we employ scanning tunneling microscopy to investigate the homocoupling reaction of linear, terminal alkyne-functionalized polyphenylene building-blocks on noble metal surfaces under ultrahigh vacuum. On the flat Ag(111) surface, thermal activation triggers a variety of side-reactions resulting in irregularly branched polymeric networks. Upon alignment along the step-edges of the Ag(877) vicinal surface drastically improves the chemoselectivity of the linking process permitting the controlled synthesis of extended-graphdiyne wires with lengths reaching 30 nm. The ideal hydrocarbon scaffold is characterized by density functional theory as a 1D, direct band gap semiconductor material with both HOMO and LUMOderived bands promisingly isolated within the electronic structure. The templating approach should be applicable to related organic precursors and different reaction schemes thus bears general promise for the engineering of novel low-dimensional carbon-based materials.
Families of carbon nanotubes: Graphyne-based nanotubes
2003
New families of carbon single-walled nanotubes are proposed and their electronic structures are investigated. These nanotubes, called graphynes, result from the elongation of covalent interconnections of graphite-based nanotubes by the introduction of yne groups. Analogously to ordinary nanotubes, armchair, zigzag, and chiral graphyne nanotubes are possible. We here predict the electronic properties of these unusual nanotubes using tight-binding and ab initio density functional methods. Of the three graphyne nanotube families analyzed here, two provide metallic behavior for armchair tubes and either metallic or semiconducting behavior for zigzag nanotubes. A diameter-and chirality-independent band gap is predicted for the other investigated graphyne family, as well as an oscillatory dependence of the effective mass on nanotube diameter.
Towards molecular electronic devices based on 'all-carbon' wires
Nanoscale, 2018
Nascent molecular electronic devices based on linear 'all-carbon' wires attached to gold electrodes through robust and reliable C-Au contacts are prepared via efficient in situ sequential cleavage of trimethylsilyl end groups from an oligoyne, MeSi-(C[triple bond, length as m-dash]C)-SiMe (1). In the first stage of the fabrication process, removal of one trimethylsilyl (TMS) group in the presence of a gold substrate, which ultimately serves as the bottom electrode, using a stoichiometric fluoride-driven process gives a highly-ordered monolayer, Au|C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CSiMe (Au|CSiMe). In the second stage, treatment of Au|CSiMe with excess fluoride results in removal of the remaining TMS protecting group to give a modified monolayer Au|C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH...
Architecture of graphdiyne nanoscale films
Chemical Communications, 2010
A new carbon allotrope -graphdiyne -was synthesized and predicted to be the most stable of non-natural carbon allotropes. Graphdiyne, a new molecular allotrope of carbon, is a two-dimensional layer with one-atom thickness and strongly bonded carbon networks, chemical stability and electrical conductivity.
Semiconductor-to-Metal Transition in Carbon-Atom Wires Driven by sp2 Conjugated End Groups
The Journal of Physical Chemistry C, 2017
Novel bis(biphenyl)-capped polyynes have been synthesized to investigate the modulation of the electronic and optical properties of sp-hybridized carbon-atom wires (CAWs) capped with π-conjugated sp 2 endgroups. Raman and Surface Enhanced Raman spectroscopy (SERS) investigation of these systems and Density Functional Theory (DFT) calculations reveal structural changes from polyyne-like with alternating single-triple bonds towards cumulene-like with more equalized bonds as a consequence of the charge transfer occurring when wires interact with metallic nanoparticles. While polyynes have semiconducting electronic properties, a more equalized system tends to a cumulene-like structure characterized by a nearly metallic behavior. The possibility to drive a semiconductor-to-metal transition has been investigated by systematic DFT calculations on a series of CAWs capped with different conjugated endgroups revealing that the modulation of the structural, electronic and vibrational properties of the sp-carbon chain towards the metallic wire cannot be simply obtained by using extended π-conjugated sp 2 carbon endgroups, but require a suitable chemical design of the endgroup and control of charge transfer. These results provide useful guidelines for the design of novel sp-sp 2 hybrid carbon nanosystems with tunable properties, where graphene-like and polyyne-like domains are closely interconnected. The capability to tune the final electronic or optical response of the material makes these hybrid sp-sp 2 systems appealing for a future all-carbon-based science and technology.
Journal of the American Chemical Society, 2022
γ-Graphyne is the most symmetric sp 2 /sp 1 allotrope of carbon, which can be viewed as graphene uniformly expanded through insertion of two-carbon acetylenic units between all the aromatic rings. To date, synthesis of bulk γ-graphyne has remained a challenge. We here report the synthesis of multilayer γ-graphyne through crystallization-assisted irreversible cross-coupling polymerization. Comprehensive characterization of this new carbon phase is described, including synchrotron X-ray diffraction, electron diffraction, lateral force microscopy, Raman and infrared spectroscopy, and cyclic voltammetry. Experiments indicate that γ-graphyne is a 0.48 eV bandgap semiconductor, with a hexagonal a-axis spacing of 6.88 Å and an interlayer spacing of 3.48 Å, which is consistent with theoretical predictions. The observed crystal structure has an aperiodic sheet stacking. The material is thermally stable up to 240 °C but undergoes a transformation at higher temperatures. While conventional 2D polymerizations and reticular chemistry rely on error correction through reversibility, we demonstrate that a periodic covalent lattice can be synthesized under purely kinetic control. The reported methodology is scalable and inspires extension to other allotropes of the graphyne family.
Nanotechnology, Science and Applications
Plenty of new two-dimensional materials including graphyne, graphdiyne, graphone, and graphane have been proposed and unveiled after the discovery of the "wonder material" graphene. Graphyne and graphdiyne are two-dimensional carbon allotropes of graphene with honeycomb structures. Graphone and graphane are hydrogenated derivatives of graphene. The advanced and unique properties of these new materials make them highly promising for applications in next generation nanoelectronics. Here, we briefly review their properties, including structural, mechanical, physical, and chemical properties, as well as their synthesis and applications in nanotechnology. Graphyne is better than graphene in directional electronic properties and charge carriers. With a band gap and magnetism, graphone and graphane show important applications in nanoelectronics and spintronics. Because these materials are close to graphene and will play important roles in carbon-based electronic devices, they deserve further, careful, and thorough studies for nanotechnology applications.
Atomically precise bottom-up fabrication of graphene nanoribbons
Nature, 2010
Graphene nanoribbons-narrow and straight-edged stripes of graphene, or single-layer graphite-are predicted to exhibit electronic properties that make them attractive for the fabrication of nanoscale electronic devices 1-3 . In particular, although the twodimensional parent material graphene 4,5 exhibits semimetallic behaviour, quantum confinement and edge effects 2,6 should render all graphene nanoribbons with widths smaller than 10 nm semiconducting. But exploring the potential of graphene nanoribbons is hampered by their limited availability: although they have been made using chemical 7-9 , sonochemical 10 and lithographic 11,12 methods as well as through the unzipping of carbon nanotubes 13-16 , the reliable production of graphene nanoribbons smaller than 10 nm with chemical precision remains a significant challenge. Here we report a simple method for the production of atomically precise graphene nanoribbons of different topologies and widths, which uses surface-assisted coupling 17,18 of molecular precursors into linear polyphenylenes and their subsequent cyclodehydrogenation 19,20 . The topology, width and edge periphery of the graphene nanoribbon products are defined by the structure of the precursor monomers, which can be designed to give access to a wide range of different graphene nanoribbons. We expect that our bottom-up approach to the atomically precise fabrication of graphene nanoribbons will finally enable detailed experimental investigations of the properties of this exciting class of materials. It should even provide a route to graphene nanoribbon structures with engineered chemical and electronic properties, including the theoretically predicted intraribbon quantum dots 21 , superlattice structures 22 and magnetic devices based on specific graphene nanoribbon edge states 3 . sketches the basic graphene nanoribbon (GNR) fabrication steps for the prototypical armchair ribbon 6 of width N 5 7 obtained from 10,109-dibromo-9,99-bianthryl precursor monomers. Thermal sublimation of the monomers onto a solid surface removes their halogen substituents, yielding the molecular building blocks of the targeted graphene ribbon in the form of surface-stabilized biradical species. During a first thermal activation step, the biradical species diffuse across the surface and undergo radical addition reactions 17 to form linear polymer chains as imprinted by the specific chemical functionality pattern of the monomers. In a second thermal activation step a surface-assisted cyclodehydrogenation establishes an extended fully aromatic system. shows GNRs obtained according to the scheme in , using precursor monomers 1 and a Au(111) surface. The first step to GNR fabrication-intermolecular colligation through radical addition-is thermally activated by annealing at 200 uC, at which temperature the dehalogenated intermediates have enough thermal energy to diffuse along the surface and form single covalent C-C bonds between each monomer to give polymer chains. Scanning tunnelling microscopy (STM) images of the colligated monomers show protrusions that appear alternately on both sides of the chain axis and with a periodicity of 0.86 nm , in excellent agreement with the periodicity of the bianthryl core of 0.85 nm. Steric hindrance between the hydrogen atoms of adjacent anthracene units rotates the latter around the s-bonds connecting them, resulting in opposite tilts of successive anthracene units with respect to the metal surface. This deviation from planarity explains the large apparent height of the polyanthrylenes of about 0.4 nm , with the finite size of the scanning probe tip moreover imaging the polymer with a width much larger (1.5 nm) than expected from the structural 1 Br Br Precursor monomer 'Biradical' intermediate Graphene nanoribbon Linear polymer Figure 1 | Bottom-up fabrication of atomically precise GNRs. Basic steps for
Designing new 2D systems with tunable properties is an important subject for science and technology. Starting from graphene, we developed an algorithm to systematically generate 2D carbon crystals belonging to the family of graphdiynes (GDYs) and having different structures and sp/sp 2 carbon ratios. We analyze how structural and topological effects can tune the relative stability and the electronic behavior, to propose a rationale for the development of new systems with tailored properties. A total of 26 structures have been generated, including the already known polymorphs such as α-, β-, and γ-GDY. Periodic density functional theory calculations have been employed to optimize the 2D crystal structures and to compute the total energy, the band structure, and the density of states. Relative energies with respect to graphene have been found to increase when the values of the carbon sp/sp 2 ratio increase, following however different trends based on the peculiar topologies present in the crystals. These topologies also influence the band structure, giving rise to semiconductors with a finite band gap, zero-gap semiconductors displaying Dirac cones, or metallic systems. The different trends allow identifying some topological effects as possible guidelines in the design of new 2D carbon materials beyond graphene.