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Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene

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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.

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(a) The strain-stress curve for P-graphene. (b) The breaking strain for P-graphene adsorbed by H2, N2, NH3, CO, CO2 or O2 molecule.
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f2: (a) The strain-stress curve for P-graphene. (b) The breaking strain for P-graphene adsorbed by H2, N2, NH3, CO, CO2 or O2 molecule.

Mentions: Before studying the strain effect on the gas-adsorbed graphene, we investigated the strain-stress relationship in the P-graphene as shown in the Fig. 2a. In an attempt to evaluate the “minimum” ideal strain for graphene, both armchair and zigzag directions seem possible to be chosen. However, a previous report40 revealed that the armchair direction possesses lower ideal strain than the zigzag direction, since it is parallel to the carbon-carbon bond which dominates the mechanics of graphene41. Therefore, only the armchair direction is considered in our calculations. Our computations show that the P-graphene sheet can sustain a maximum stress up to ~32 N/m and its structure does not fracture even when the strain exceeds 30% (Fig. 2b), which is in consistent with previous theoretical work40.


Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene
(a) The strain-stress curve for P-graphene. (b) The breaking strain for P-graphene adsorbed by H2, N2, NH3, CO, CO2 or O2 molecule.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: (a) The strain-stress curve for P-graphene. (b) The breaking strain for P-graphene adsorbed by H2, N2, NH3, CO, CO2 or O2 molecule.
Mentions: Before studying the strain effect on the gas-adsorbed graphene, we investigated the strain-stress relationship in the P-graphene as shown in the Fig. 2a. In an attempt to evaluate the “minimum” ideal strain for graphene, both armchair and zigzag directions seem possible to be chosen. However, a previous report40 revealed that the armchair direction possesses lower ideal strain than the zigzag direction, since it is parallel to the carbon-carbon bond which dominates the mechanics of graphene41. Therefore, only the armchair direction is considered in our calculations. Our computations show that the P-graphene sheet can sustain a maximum stress up to ~32 N/m and its structure does not fracture even when the strain exceeds 30% (Fig. 2b), which is in consistent with previous theoretical work40.

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