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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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The structural configurations for the NH3 decomposition on the D-graphene sheet with (a,b) 0%, (c) 12.8% and (d) 16.0% strain. (d) The stress (σ) versus biaxial strain ε for NH3 adsorption in defective graphene.
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f5: The structural configurations for the NH3 decomposition on the D-graphene sheet with (a,b) 0%, (c) 12.8% and (d) 16.0% strain. (d) The stress (σ) versus biaxial strain ε for NH3 adsorption in defective graphene.

Mentions: The high possibility of NH3 decomposition on defective graphene, as revealed by our NEB calculations, is further verified by the optimized structural configuration of NH3 + D-graphene system (Fig. 5). The NH3 decomposition happens above the D-graphene sheet. When the strain is less than 12.8%, the NH3 molecule is dissociated into NH2 and H, NH2 is physisorbed at the carbon atom with a dangling bond, while H bonds to a neighbouring carbon atom (-c-H) (Fig. 5a–c). This dissociative NH3 adsorption induces obvious corrugation on the D-graphene layer (Fig. 5b) due to the strong electron coupling between the adsorbed species and the D-graphene sheet.


Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene
The structural configurations for the NH3 decomposition on the D-graphene sheet with (a,b) 0%, (c) 12.8% and (d) 16.0% strain. (d) The stress (σ) versus biaxial strain ε for NH3 adsorption in defective graphene.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: The structural configurations for the NH3 decomposition on the D-graphene sheet with (a,b) 0%, (c) 12.8% and (d) 16.0% strain. (d) The stress (σ) versus biaxial strain ε for NH3 adsorption in defective graphene.
Mentions: The high possibility of NH3 decomposition on defective graphene, as revealed by our NEB calculations, is further verified by the optimized structural configuration of NH3 + D-graphene system (Fig. 5). The NH3 decomposition happens above the D-graphene sheet. When the strain is less than 12.8%, the NH3 molecule is dissociated into NH2 and H, NH2 is physisorbed at the carbon atom with a dangling bond, while H bonds to a neighbouring carbon atom (-c-H) (Fig. 5a–c). This dissociative NH3 adsorption induces obvious corrugation on the D-graphene layer (Fig. 5b) due to the strong electron coupling between the adsorbed species and the D-graphene sheet.

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