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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.


(a) Top and (b) side view of the relaxed structural model of gas (NH3) adsorption on the perfect graphene monolayer.
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f1: (a) Top and (b) side view of the relaxed structural model of gas (NH3) adsorption on the perfect graphene monolayer.

Mentions: As a representative, the case for NH3 is presented in Fig. 1. The NH3 molecule prefers to locate in the hexagon center (Fig. 1a), and the calculated distance (see Table 1) between the NH3 molecules and graphene is 2.84 Å. The computed adsorbent-graphene distances, adsorption energies, and magnetic moments for other gas molecules (H2, N2, CO, CO2 and O2) are given in the Table 1. In the equilibrium, all these gas molecules are physically adsorbed on graphene with a distance between 2.68–3.32 Å. However, only the adsorption of H2, NH3 and O2 is exothermic while others are not favoured energetically, and only O2 adsorbed system is magnetic.


Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene
(a) Top and (b) side view of the relaxed structural model of gas (NH3) adsorption on the perfect graphene monolayer.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: (a) Top and (b) side view of the relaxed structural model of gas (NH3) adsorption on the perfect graphene monolayer.
Mentions: As a representative, the case for NH3 is presented in Fig. 1. The NH3 molecule prefers to locate in the hexagon center (Fig. 1a), and the calculated distance (see Table 1) between the NH3 molecules and graphene is 2.84 Å. The computed adsorbent-graphene distances, adsorption energies, and magnetic moments for other gas molecules (H2, N2, CO, CO2 and O2) are given in the Table 1. In the equilibrium, all these gas molecules are physically adsorbed on graphene with a distance between 2.68–3.32 Å. However, only the adsorption of H2, NH3 and O2 is exothermic while others are not favoured energetically, and only O2 adsorbed system is magnetic.

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.