Limits...
Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene

View Article: PubMed Central - PubMed

ABSTRACT

Pure graphene is known as the strongest material ever discovered. However, the unavoidable defect formation in the fabrication process renders the strength of defective graphene much lower (~14%) than that of its perfect counterpart. By means of density functional theory computations, we systematically explored the effect of gas molecules (H2, N2, NH3, CO, CO2 and O2) adsorption on the mechanical strength of perfect/defective graphene. The NH3 molecule is found to play a dominant role in enhancing the strength of defective graphene by up to ~15.6%, while other gas molecules decrease the strength of graphene with varying degrees. The remarkable strength enhancement can be interpreted by the decomposition of NH3, which saturates the dangling bond and leads to charge redistribution at the defect site. The present work provides basic information for the mechanical failure of gas-adsorbed graphene and guidance for manufacturing graphene-based electromechanical devices.

No MeSH data available.


Related in: MedlinePlus

The energy barrier (Ea) of NH3 dissociation on the defective graphene with the increase of strain.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5036057&req=5

f4: The energy barrier (Ea) of NH3 dissociation on the defective graphene with the increase of strain.

Mentions: With regard to the NH3 adsorption on defective graphene, experimentally it has been demonstrated that the NH3 molecule can easily dissociate on this host layer43. To validate the possibility of gas decomposition, we performed the nudged elastic band (NEB)44 DFT calculations for the NH3 + D-graphene system at different strains, as shown in Fig. 4. By computing the transition states, we find that the NH3 decomposition needs to overcome an energy barrier (Ea) of 0.5 eV for the strain-free D-graphene, while the Ea value decreases as the strain increases. As a 0.5 eV energy barrier is not sufficient to hinder the NH3 decomposition, it is reasonable to expect the NH3 decomposition to occur without stain, while the finite strains can accelerate this process.


Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene
The energy barrier (Ea) of NH3 dissociation on the defective graphene with the increase of strain.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036057&req=5

f4: The energy barrier (Ea) of NH3 dissociation on the defective graphene with the increase of strain.
Mentions: With regard to the NH3 adsorption on defective graphene, experimentally it has been demonstrated that the NH3 molecule can easily dissociate on this host layer43. To validate the possibility of gas decomposition, we performed the nudged elastic band (NEB)44 DFT calculations for the NH3 + D-graphene system at different strains, as shown in Fig. 4. By computing the transition states, we find that the NH3 decomposition needs to overcome an energy barrier (Ea) of 0.5 eV for the strain-free D-graphene, while the Ea value decreases as the strain increases. As a 0.5 eV energy barrier is not sufficient to hinder the NH3 decomposition, it is reasonable to expect the NH3 decomposition to occur without stain, while the finite strains can accelerate this process.

View Article: PubMed Central - PubMed

ABSTRACT

Pure graphene is known as the strongest material ever discovered. However, the unavoidable defect formation in the fabrication process renders the strength of defective graphene much lower (~14%) than that of its perfect counterpart. By means of density functional theory computations, we systematically explored the effect of gas molecules (H2, N2, NH3, CO, CO2 and O2) adsorption on the mechanical strength of perfect/defective graphene. The NH3 molecule is found to play a dominant role in enhancing the strength of defective graphene by up to ~15.6%, while other gas molecules decrease the strength of graphene with varying degrees. The remarkable strength enhancement can be interpreted by the decomposition of NH3, which saturates the dangling bond and leads to charge redistribution at the defect site. The present work provides basic information for the mechanical failure of gas-adsorbed graphene and guidance for manufacturing graphene-based electromechanical devices.

No MeSH data available.


Related in: MedlinePlus