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Introduction
Published in Satyendra Mishra, Dharmesh Hansora, Graphene Nanomaterials, 2017
Satyendra Mishra, Dharmesh Hansora
Graphene-based carbon NMs [28, 64, 65] mainly include (i) graphene oxide (GO), (ii) doped graphene (iii) derived graphene nanoribbons (GNRs), (iv) graphane, (v) fluorographene, (vi) graphyne (vii) graphdiyne, (viii) graphone and (ix) porous graphene. Graphene is a semimetal with zero band gap, i.e. conduction and valence bands meet at the Dirac point. A zero band gap can be easily tuned by doping and cutting the 2D graphene into form of 1D GNRs [20, 66]. GO is an oxidised and functionalised derivative and it has been reported as hydrophilic material because it has ability of water dispersion. GO adheres on interfaces due to its lower interfacial energy, so it has been widely used as surfactant for emulsification of organic solvents in water. It has been used for the dispersion of insoluble graphite and CNTs in water. This capability strengthens it for development of graphene and P-conjugated systems-based functional hybrid NMs [66, 67]. Graphane is hydrogenated form of graphene sheet. It is a non-magnetic semiconductor having an energy gap due to hydrogenation. Graphane is a hydrocarbon with a stoichiometry formula unit of CH, i.e. extended 2D polymer form of carbon. It generally adds a wealth to the carbon-based NMs useful for hydrogen storage and nanoelectronic applications. Generally, the hydrogen atoms alternate the directions along with the graphane sheet and transform the carbon lattice from sp2 to sp3 hybridisation. Graphane can be easily transformed back into original graphene sheets by annealing process. Fluorographene, with stoichiometric formula of CF, is an another important structure of graphene. Fluorographene has a geometric structure and sp3 bonding configuration similar to graphane with each carbon attached to one fluorine atom. Fluorographene has been used as a solid lubricant for developing the batteries under extreme conditions. Graphyne and graphdiyne are another non-natural carbon allotropes, which have better potential than graphene due to their unique structures, electronic and intriguing properties. Graphyne is a one-atom-thick planar sheet of sp- and sp2-bonded carbon atoms arranged in a crystal lattice form. Graphydine has acetylenic linkages connecting the hexagons of graphene. Graphone, is known as a semi-hydrogenated derivative of graphene, having stoichiometric formula of C2H [65]. In graphone structure, hydrogen atoms are attached on either side of the carbon sheet and graphone is also known as a hybridised mixture of sp2 and sp3 carbon atoms. A porous graphene is a another new class of light weight carbonaceous material. It has a distributed structure within the covalent p-electronic framework of graphene sheet.
Computation of some important degree-based topological indices for γ- graphyne and Zigzag graphyne nanoribbon
Published in Molecular Physics, 2023
Abdul Hakeem, Asad Ullah, Shahid Zaman
Numerous allotropes are produced when neighbouring carbon atoms hybridise at the sp3, sp2, or sp levels to create single, double, or even triple bonds. Graphite and diamond are the two most well-known carbon allotropes formed exclusively of carbon atoms that have undergone sp2 and sp3 hybridisation. [39–45]. Carbon allotropes exhibit distinctive physical characteristics because of the special pairing and arrangement of several types of bonds with varying lengths, strengths, geometries, and electronic properties. For instance, graphite is opaque and soft. A tremendous amount of research has gone into creating novel carbon allotropes, For example, fullerene (which obtained the Nobel Prize in Chemistry in 1996) [46], carbon nanotubes [42], graphene (which got the Nobel Prize in Physics in 2010) [47] a chain of biphenylene [48] and Carbon (which awarded the Nobel Prize in Physics in 2010 [49,50]. Two-dimensional (2D) carbon allotropes of Carbon are known as graphynes. The discovery of graphene inaugurated a new era of quantum technology and 2D materials. Researchers have been putting efforts into synthesising a novel carbon form termed graphyne for over a decade but with no success. Recently, some researchers have made a breakthrough in generating Carbon's elusive allotrope [51] and solved a long-standing problem in the field of carbon materials. This wonder material is created in such a way that it could rival the conductivity of graphene, but with control. These results opened new ways of research in the fields of semiconductor, electronics and optics.
Molecular dynamics study for CH4/H2S separation through functionalized nanoporous graphyne membrane
Published in Petroleum Science and Technology, 2019
Roghayeh Jafarzadeh, Jafar Azamat, Hamid Erfan-Niya
A progress in material science is made by the advent of graphene as a 2D carbon material due to its unique and exceptional properties. Also, scientists and engineers have great interest in the other 2D carbon allotropes such as graphyne and graphdiyne. Graphyne is a class of graphene allotropes with two-dimensional lattice of sp–sp2-hybridized carbon atoms (Baughman et al. 1987). The proposed structures of graphyne are derived by inserting acetylene bonds instead of carbon–carbon single bonds in a graphene lattice. The main difference between graphyne and graphdiyne is the number of acetylenic (one and two, respectively) groups connecting benzene rings. These materials have been theoretically predicted in 1987 (Baughman, Eckhardt, and Kertesz 1987); however, some of these structures have been experimentally realized due to the intrinsic difficulties in their synthesis.
On the thermal conductivity of the α2-graphyne nanotubes: A molecular dynamics investigation
Published in Mechanics of Advanced Materials and Structures, 2022
After the realization of the graphene by the experiments in 2004 [1], different researches have been conducted to evaluate its physical properties. Due to the considerable physical properties of the graphene, other two-dimensional nanostructures such as pentagraphene [2], phagraphene [3] and the graphynes [4–6] were also investigated looking for the same great characteristics. The latter mentioned nanostructure, i.e. graphyne, is one of the most important structures that due to its applications in different fields such as energy storage [7, 8] and water purifcation [9, 10] have been extensively studied.