Graphyne

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Graphyne
Graphyne v2.svg
Chemical structure of graphyne-1
Identifiers
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Graphyne-n varieties, where n indicates the number of carbon-carbon triple bonds in a link between two adjacent hexagons. Graphyne is graphyne-1; graphdiyne is graphyne-2. Graphynes.png
Graphyne-n varieties, where n indicates the number of carbon–carbon triple bonds in a link between two adjacent hexagons. Graphyne is graphyne-1; graphdiyne is graphyne-2.

Graphyne is an allotrope of carbon. Although it has been studied in theoretical models, it is very difficult to synthesize and only small amounts of uncertain purity have been created. Its structure is one-atom-thick planar sheets of sp and sp2-bonded carbon atoms arranged in crystal lattice. It can be seen as a lattice of benzene rings connected by acetylene bonds. The material is called graphyne-n when benzene rings are connected by n sequential acetylene molecules, and graphdiyne for a particular case of n = 2 (diacetylene links).

Contents

Depending on the content of acetylene groups, graphyne can be considered a mixed hybridization, spk, where k can be 1 or 2, [1] [2] and thus differs from the hybridization of graphene (considered pure sp2) and diamond (pure sp3).

First-principles calculations showed that periodic graphyne structures and their boron nitride analogues are stable. The calculations used phonon dispersion curves and ab-initio finite temperature, quantum mechanical molecular dynamics simulations. [3]

History

Graphyne was first theoretically proposed by Baughman et al. in 1987. [4] In 2010, Li et al. developed the first successful methodology for creating graphdiyne films using the Glaser–Hay cross-coupling reaction with hexaethynylbenzene. [5] The proposed approach makes it possible to synthesize nanometer-scale graphdiyne and graphtetrayne, which lack long-range order. In 2019, Cui and co-workers reported on a mechanochemical technique for obtaining graphyne using benzene and calcium carbide. [6] Although a gram-scale graphyne can be obtained using this approach, graphynes with long-range crystallinity over a large area remain elusive.

In 2022, synthesis of multi-layered γ‑graphyne was successfully performed through the polymerization of 1,3,5-tribromo-2,4,6-triethynylbenzene under Sonogashira coupling conditions. Near-infrared spectroscopy and cyclic voltammetry of the material determined the bandgap as 0.48 ± 0.05 eV, which agrees with the theoretical prediction for graphyne-based materials. [7] : 4  [8]

Synthesis

Despite numerous efforts by different approaches, no synthesis method has been discovered to create quality graphyne. The small impure amounts created to date do not allow characterization sufficient to verify theoretical properties. [7] : 12 

Structure

Through the use of computer models scientists have predicted several properties of the substance on assumed geometries of the lattice. Its proposed structures are derived from inserting acetylene bonds in place of carbon-carbon single bonds in a graphene lattice. [9] Graphyne is theorized to exist in multiple geometries. This variety is due to the multiple arrangements of sp and sp2 hybridized carbon. The proposed geometries include a hexagonal lattice structure and a rectangular lattice structure. [10] Out of the theorized structures the rectangular lattice of 6,6,12-graphyne may hold the most potential for future applications.

Properties

Models predict that graphyne has the potential for Dirac cones on its double and triple bonded carbon atoms.[ citation needed ] Due to the Dirac cones, the conduction and valence bands meet in a linear fashion at a single point in the Fermi level. The advantage of this scheme is that electrons behave as if they have no mass, resulting in energies that are proportional to the momentum of the electrons. Like in graphene, hexagonal graphyne has electric properties that are direction independent. However, due to the symmetry of the proposed rectangular 6,6,12-graphyne the electric properties would change along different directions in the plane of the material. [10] This unique feature of its symmetry allows graphyne to self-dope meaning that it has two different Dirac cones lying slightly above and below the Fermi level. [10] The self-doping effect of 6,6,12-graphyne can be effectively tuned by applying in-plane external strain. [11] Graphyne samples synthesized to date have shown a melting point of 250-300 °C, low reactivity in decomposition reactions with oxygen, heat and light. [9]

Potential applications

It has been hypothesized that graphyne is preferable to graphene for specific applications owing to its particular energy structure, namely direction-dependent Dirac cones. [12] [13] The directional dependency of 6,6,12-graphyne could allow for electrical grating on the nanoscale. [14] This could lead to the development of faster transistors and nanoscale electronic devices. [10] [15] [16] Recently it was demonstrated that photoinduced electron transfer from electron-donating partners to γ-graphyne is favorable and occurs on nano to sub-picosecond time scale. [17]

Related Research Articles

<span class="mw-page-title-main">Allotropy</span> Property of some chemical elements to exist in two or more different forms

Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements. Allotropes are different structural modifications of an element: the atoms of the element are bonded together in different manners. For example, the allotropes of carbon include diamond, graphite, graphene, and fullerenes.

<span class="mw-page-title-main">Fullerene</span> Allotrope of carbon

A fullerene is an allotrope of carbon whose molecules consist of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms. The molecules may have hollow sphere- and ellipsoid-like forms, tubes, or other shapes.

A carbon–carbon bond is a covalent bond between two carbon atoms. The most common form is the single bond: a bond composed of two electrons, one from each of the two atoms. The carbon–carbon single bond is a sigma bond and is formed between one hybridized orbital from each of the carbon atoms. In ethane, the orbitals are sp3-hybridized orbitals, but single bonds formed between carbon atoms with other hybridizations do occur. In fact, the carbon atoms in the single bond need not be of the same hybridization. Carbon atoms can also form double bonds in compounds called alkenes or triple bonds in compounds called alkynes. A double bond is formed with an sp2-hybridized orbital and a p-orbital that is not involved in the hybridization. A triple bond is formed with an sp-hybridized orbital and two p-orbitals from each atom. The use of the p-orbitals forms a pi bond.

<span class="mw-page-title-main">Allotropes of carbon</span> Materials made only out of carbon

Carbon is capable of forming many allotropes due to its valency (tetravalent). Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene. Larger-scale structures of carbon include nanotubes, nanobuds and nanoribbons. Other unusual forms of carbon exist at very high temperatures or extreme pressures. Around 500 hypothetical 3‑periodic allotropes of carbon are known at the present time, according to the Samara Carbon Allotrope Database (SACADA).

<span class="mw-page-title-main">Graphene</span> Hexagonal lattice made of carbon atoms

Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a honeycomb nanostructure. The name is derived from "graphite" and the suffix -ene, reflecting the fact that the graphite allotrope of carbon contains numerous double bonds in a two dimensional sheet.

Amorphous carbon is free, reactive carbon that has no crystalline structure. Amorphous carbon materials may be stabilized by terminating dangling-π bonds with hydrogen. As with other amorphous solids, some short-range order can be observed. Amorphous carbon is often abbreviated to aC for general amorphous carbon, aC:H or HAC for hydrogenated amorphous carbon, or to ta-C for tetrahedral amorphous carbon.

<span class="mw-page-title-main">Carbon nanobud</span> Synthetic allotrope of carbon combining carbon nanotube and a fullerene

In nanotechnology, a carbon nanobud is a material that combines carbon nanotubes and spheroidal fullerenes, both allotropes of carbon, forming "buds" attached to the tubes. Carbon nanobuds were discovered and synthesized in 2006.

<span class="mw-page-title-main">Allotropes of phosphorus</span> Solid forms of the element phosphorus

Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus.

<span class="mw-page-title-main">Linear acetylenic carbon</span> Polymer made of repeating −C≡C− units

Linear acetylenic carbon (LAC), also known as carbyne or Linear Carbon Chain (LCC), is an allotrope of carbon that has the chemical structure (−C≡C−)n as a repeat unit, with alternating single and triple bonds. It would thus be the ultimate member of the polyyne family.

<span class="mw-page-title-main">Graphane</span> Chemical compound

Graphane is a two-dimensional polymer of carbon and hydrogen with the formula unit (CH)n where n is large. Partial hydrogenation results in hydrogenated graphene, which was reported by Elias et al. in 2009 by a TEM study to be "direct evidence for a new graphene-based derivative". The authors viewed the panorama as "a whole range of new two-dimensional crystals with designed electronic and other properties". With the band gap ranges from 0 to 0.8 eV

<span class="mw-page-title-main">Fluorographene</span> Chemical compound

Fluorographene (or perfluorographane, graphene fluoride) is a fluorocarbon derivative of graphene. It is a two dimensional carbon sheet of sp3 hybridized carbons, with each carbon atom bound to one fluorine. The chemical formula is (CF)n. In comparison, Teflon (polytetrafluoroethylene), -(CF2)n-, consists of carbon "chains" with each carbon bound to two fluorines.

<span class="mw-page-title-main">Silicene</span> Two-dimensional allotrope of silicon

Silicene is a two-dimensional allotrope of silicon, with a hexagonal honeycomb structure similar to that of graphene. Contrary to graphene, silicene is not flat, but has a periodically buckled topology; the coupling between layers in silicene is much stronger than in multilayered graphene; and the oxidized form of silicene, 2D silica, has a very different chemical structure from graphene oxide.

Silicynes are allotropes of silicon.

In materials science, the term single-layer materials or 2D materials refers to crystalline solids consisting of a single layer of atoms. These materials are promising for some applications but remain the focus of research. Single-layer materials derived from single elements generally carry the -ene suffix in their names, e.g. graphene. Single-layer materials that are compounds of two or more elements have -ane or -ide suffixes. 2D materials can generally be categorized as either 2D allotropes of various elements or as compounds.

<span class="mw-page-title-main">Germanene</span> Bi-dimensional crystalline structure of germanium

Germanene is a material made up of a single layer of germanium atoms. The material is created in a process similar to that of silicene and graphene, in which high vacuum and high temperature are used to deposit a layer of germanium atoms on a substrate. High-quality thin films of germanene have revealed unusual two-dimensional structures with novel electronic properties suitable for semiconductor device applications and materials science research.

<span class="mw-page-title-main">Carbon nanothread</span> Carbon crystalline nanomaterial

A carbon nanothread is a sp3-bonded, one-dimensional carbon crystalline nanomaterial. The tetrahedral sp3-bonding of its carbon is similar to that of diamond. Nanothreads are only a few atoms across, more than 300,000 times thinner than a human hair. They consist of a stiff, strong carbon core surrounded by hydrogen atoms. Carbon nanotubes, although also one-dimensional nanomaterials, in contrast have sp2-carbon bonding as is found in graphite. The smallest carbon nanothread has a diameter of only 0.2 nanometers, much smaller than the diameter of a single-wall carbon nanotube.

<span class="mw-page-title-main">Penta-graphene</span> Chemical compound

Penta-graphene is a hypothetical carbon allotrope composed entirely of carbon pentagons and resembling the Cairo pentagonal tiling. Penta-graphene was proposed in 2014 on the basis of analyses and simulations. Further calculations predicted that it is unstable in its pure form, but can be stabilized by hydrogenation. Due to its atomic configuration, penta-graphene has an unusually negative Poisson’s ratio and very high ideal strength believed to exceed that of a similar material, graphene.

A rapidly increasing list of graphene production techniques have been developed to enable graphene's use in commercial applications.

<span class="mw-page-title-main">Electronic properties of graphene</span>

Graphene is a semimetal whose conduction and valence bands meet at the Dirac points, which are six locations in momentum space, the vertices of its hexagonal Brillouin zone, divided into two non-equivalent sets of three points. The two sets are labeled K and K′. The sets give graphene a valley degeneracy of gv = 2. By contrast, for traditional semiconductors the primary point of interest is generally Γ, where momentum is zero. Four electronic properties separate it from other condensed matter systems.

The term Dirac matter refers to a class of condensed matter systems which can be effectively described by the Dirac equation. Even though the Dirac equation itself was formulated for fermions, the quasi-particles present within Dirac matter can be of any statistics. As a consequence, Dirac matter can be distinguished in fermionic, bosonic or anyonic Dirac matter. Prominent examples of Dirac matter are graphene and other Dirac semimetals, topological insulators, Weyl semimetals, various high-temperature superconductors with -wave pairing and liquid helium-3. The effective theory of such systems is classified by a specific choice of the Dirac mass, the Dirac velocity, the gamma matrices and the space-time curvature. The universal treatment of the class of Dirac matter in terms of an effective theory leads to a common features with respect to the density of states, the heat capacity and impurity scattering.

References

  1. ↑ Heimann, R.B.; Evsvukov, S.E.; Koga, Y. (1997). "Carbon allotropes: a suggested classification scheme based on valence orbital hybridization". Carbon . 35 (10–11): 1654–1658. doi:10.1016/S0008-6223(97)82794-7.
  2. ↑ Enyashin, Andrey N.; Ivanovskii, Alexander L. (2011). "Graphene Allotropes". Physica Status Solidi B . 248 (8): 1879–1883. Bibcode:2011PSSBR.248.1879E. doi: 10.1002/pssb.201046583 . S2CID   125591804.
  3. ↑ Özçelik, V. Ongun; Ciraci, S. (January 10, 2013). "Size Dependence in the Stabilities and Electronic Properties of α-Graphyne and Its Boron Nitride Analogue". The Journal of Physical Chemistry C. 117 (5): 2175–2182. arXiv: 1301.2593 . doi:10.1021/jp3111869. S2CID   44136901.
  4. ↑ Baughman, R. H.; Eckhardt, H.; Kertesz, M. (1987). "Structure‐property predictions for new planar forms of carbon: Layered phases containing sp2 and sp atoms". The Journal of Chemical Physics. 87 (11): 6687–6699. Bibcode:1987JChPh..87.6687B. doi:10.1063/1.453405.
  5. ↑ Li, G.; Li, Y.; Lui, H.; Guo, Y.; Li, Y.; Zhu, D. (2010). "Architecture of graphdiyne nanoscale films". Chemical Communications. 46 (19): 3256–3258. doi:10.1039/B922733D. PMID   20442882.
  6. ↑ Li, Q.; Yang, C.; Wu, L.; Wang, H.; Cui, X. (2019). "Converting benzene into γ-graphyne and its enhanced electrochemical oxygen evolution performance". Journal of Materials Chemistry A. 7 (11): 5981–5990. doi:10.1039/C8TA10317H. S2CID   104431102.
  7. 1 2 Li, Jiaqiang; Han, Yu (2023-03-01). "Artificial carbon allotrope γ-graphyne: Synthesis, properties, and applications". Giant. 13: 100140. doi:10.1016/j.giant.2023.100140. ISSN   2666-5425.
  8. ↑ Desyatkin, V. G.; Martin, W. B.; Aliev, A. E.; Chapman, N. E.; Fonseca, A. F.; Galvão, D. S.; Miller, E. R.; Stone, K. H.; Wang, Z.; Zakhidov, D.; Limpoco, F. T.; Almahdali, S. R.; Parker, S. M.; Baughman, R. H.; Rodionov, V. O. (2022). "Scalable Synthesis and Characterization of Multilayer γ‑Graphyne, New Carbon Crystals with a Small Direct Band Gap". Journal of the American Chemical Society. 144 (39): 17999–18008. arXiv: 2301.05291 . doi:10.1021/jacs.2c06583. PMID   36130080. S2CID   252438218.
  9. 1 2 Kim, Bog G.; Choi, Hyoung Joon (2012). "Graphyne: Hexagonal network of carbon with versatile Dirac cones". Physical Review B . 86 (11): 115435. arXiv: 1112.2932 . Bibcode:2012PhRvB..86k5435K. doi:10.1103/PhysRevB.86.115435. S2CID   119288235.
  10. 1 2 3 4 Dumé, Belle (1 March 2012). "Could graphynes be better than graphene?". Physics World . Institute of Physics.
  11. ↑ Wang, Gaoxue; Si, Mingsu; Kumar, Ashok; Pandey, Ravindra (May 26, 2014). "Strain engineering of Dirac cones in graphyne". Applied Physics Letters. 104 (21): 213107. Bibcode:2014ApPhL.104u3107W. doi:10.1063/1.4880635.
  12. ↑ Malko, Daniel; Neiss, Christian; Viñes, Francesc; Görling, Andreas (24 February 2012). "Competition for Graphene: Graphynes with Direction-Dependent Dirac Cones" (PDF). Phys. Rev. Lett. 108 (8): 086804. Bibcode:2012PhRvL.108h6804M. doi:10.1103/PhysRevLett.108.086804. hdl: 2445/65316 . PMID   22463556.
  13. ↑ Schirber, Michael (24 February 2012). "Focus: Graphyne May Be Better than Graphene". Physics . 5 (24): 24. Bibcode:2012PhyOJ...5...24S. doi:10.1103/Physics.5.24.
  14. ↑ Bardhan, Debjyoti (2 March 2012). "Novel new material graphyne can be a serious competitor to graphene". techie-buzz.com.
  15. ↑ Cartwright, J. (1 March 2012). "Graphyne could be better than graphene". news.sciencemag.org. Archived from the original on 2 October 2012.
  16. ↑ "Graphyne Better Than Graphene?". Materials Today. 5 March 2012.
  17. ↑ Stasyuk, O.A.; Stasyuk, A.J.; Solà, M.; Voityuk, A.A. (2022). "γ-graphyne: a promising electron acceptor for organic photovoltaics". Materials & Design. 225: 111526. doi:10.1016/j.matdes.2022.111526. hdl: 10256/22532 . S2CID   254961210.
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