Site Dependent Hydrogenation in Graphynes: A Fully Atomistic Molecular Dynamics Investigation

ABSTRACTGraphyne is a generic name for a carbon allotrope family of 2D structures, where acetylenic groups connect benzenoid rings, with the coexistence of sp and sp2 hybridized carbon atoms. In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics and structural changes of the hydrogenation of α, β, and γ graphyne forms. Our results showed that the existence of different sites for hydrogen bonding, related to single and triple bonds, makes the process of incorporating hydrogen atoms into graphyne membranes much more complex than the graphene ones. Our results also show that hydrogenation reactions are strongly site dependent and that the sp-hybridized carbon atoms are the preferential sites to chemical attacks. In our cases, the effectiveness of the hydrogenation (estimated from the number of hydrogen atoms covalently bonded to carbon atoms) follows the α, β, γ-graphyne structure ordering.

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Graphyne Oxidation: Insights From a Reactive Molecular Dynamics Investigation

MRS Proceedings ◽

10.1557/opl.2013.941 ◽

2013 ◽

Vol 1549 ◽

pp. 53-58 ◽

Cited By ~ 4

Author(s):

L. D. Machado ◽

P. A. S. Autreto ◽

D. S. Galvao

Keyword(s):

Molecular Dynamics ◽

Structural Changes ◽

Single Layer ◽

Oxidation Reactions ◽

Carbon Allotrope ◽

Reactive Molecular Dynamics ◽

Triple Bonds ◽

Covalently Bonded ◽

Dynamics Simulations ◽

Oxygen Atoms

ABSTRACTGraphyne is a generic name for a family of carbon allotrope two-dimensional structures where sp2 (single and double bonds) and sp (triple bonds) hybridized states coexists. They exhibit very interesting electronic and mechanical properties sharing some of the unique graphene characteristics. Similarly to graphene, the graphyne electronic properties can be modified by chemical functionalization, such as; hydrogenation, fluorination and oxidation. Oxidation is of particular interest since it can produce significant structural damages.In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics and structural changes of the oxidation of single-layer graphyne membranes at room temperature. We have considered α, β, and γ-graphyne structures. Our results showed that the oxidation reactions are strongly site dependent and that the sp-hybridized carbon atoms are the preferential sites to chemical attacks. Our results also showed that the effectiveness of the oxidation (estimated from the number of oxygen atoms covalently bonded to carbon atoms) follows the α, β, γ-graphyne structure ordering. These differences can be explained by the fact that for α-graphyne structures the oxidation reactions occur in two steps: first, the oxygen atoms are trapped at the center of the large polygonal rings and then they react with the carbon atoms composing of the triple bonds. The small rings of γ-graphyne structures prevent these reactions to occur. The effectiveness of β-graphyne oxidation is between the α- and γ-graphynes.

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Dynamics of Synthesis of Large Carbon Structures in the Interstellar Medium

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313016116 ◽

2013 ◽

Vol 9 (S297) ◽

pp. 353-355

Author(s):

N. Patra ◽

H. R. Sadeghpour

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Gas Phase ◽

Particle Density ◽

Hydrogen Atoms ◽

Reactive Molecular Dynamics ◽

Carbon Chains ◽

Carbon Structures ◽

Dynamics Simulations ◽

Different Characteristics

AbstractWe investigate the nucleation of carbon and hydrogen atoms in the gas phase to form large carbon chains, clusters and cages by reactive molecular dynamics simulations. We study how temperature, particle density, presence of hydrogen, and carbon inflow affect the nucleation of molecular moieties with different characteristics.

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Mechanical Properties of Protomene: A Molecular Dynamics Investigation

MRS Advances ◽

10.1557/adv.2018.670 ◽

2019 ◽

Vol 4 (3-4) ◽

pp. 191-196 ◽

Cited By ~ 2

Author(s):

Eliezer F. Oliveira ◽

Pedro A. S. Autreto ◽

Cristiano F. Woellner ◽

Douglas S. Galvao

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Ultimate Strength ◽

Carbon Allotrope ◽

Mechanical Fracture ◽

Reactive Molecular Dynamics ◽

New Class ◽

A Value ◽

Reaxff Force Field ◽

Dynamics Simulations

ABSTRACTRecently, a new class of carbon allotrope called protomene was proposed. This new structure is composed of sp2 and sp3 carbon-bonds. Topologically, protomene can be considered as an sp3 carbon structure (∼80% of this bond type) doped by sp2 carbons. First-principles simulations have shown that protomene presents an electronic bandgap of ∼3.4 eV. However, up to now, its mechanical properties have not been investigated. In this work, we have investigated protomene mechanical behavior under tensile strain through fully atomistic reactive molecular dynamics simulations using the ReaxFF force field, as available in the LAMMPS code. At room temperature, our results show that the protomene is very stable and the obtained ultimate strength and ultimate stress indicates an anisotropic behavior. The highest ultimate strength was obtained for the x-direction, with a value of ∼110 GPa. As for the ultimate strain, the highest one was for the z-direction (∼25% of strain) before protomene mechanical fracture.

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Mechanical Properties of Phagraphene Membranes: A Fully Atomistic Molecular Dynamics Investigation

MRS Advances ◽

10.1557/adv.2018.54 ◽

2018 ◽

Vol 3 (1-2) ◽

pp. 67-72 ◽

Cited By ~ 2

Author(s):

J. M. de Sousa ◽

A. L. Aguiar ◽

E. C. Girão ◽

Alexandre F. Fonseca ◽

A. G. Sousa Filho ◽

...

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Carbon Allotrope ◽

Reactive Molecular Dynamics ◽

Elastic Regime ◽

Fracture Patterns ◽

Anisotropic Thermal Conductivity ◽

Reaxff Force Field ◽

Dynamics Simulations ◽

Comprehensive Study

ABSTRACTRecently, a new 2D carbon allotrope structure, named phagraphene (PG), was proposed. PG has a densely array of penta-hexa-hepta-graphene carbon rings. PG was shown to present low and anisotropic thermal conductivity and it is believed that this anisotropy should be also reflected in its mechanical properties. Although PG mechanical properties have been investigated, a detailed and comprehensive study is still lacking. In the present work we have carried out fully atomistic reactive molecular dynamics simulations using the ReaxFF force field, to investigate the mechanical properties and fracture patterns of PG membranes. The Young’s modulus values of the PG membranes were estimated from the stress-strain curves. Our results show that these curves present three distinct regimes: one regime where ripples dominate the structure and mechanical properties of the PG membranes; an elastic regime where the membranes exhibit fully planar configurations; and finally am inelastic regime where permanent deformations happened to the PG membrane up to the mechanical failure or fracture.

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