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Electronic Structures, Bonding Configurations, and Band-Gap-Opening Properties of Graphene Binding with Low-Concentration Fluorine.

Duan Y, Stinespring CD, Chorpening B - ChemistryOpen (2015)

Bottom Line: The lowest-binding energy state is found to correspond to two CF defects on nearest neighbor sites, with one fluorine above the carbon plane and the other below the plane.The binding energy decreases with decreasing fluorine concentration due to the interaction between neighboring fluorine atoms.The obtained results are useful for sensor development and nanoelectronics.

View Article: PubMed Central - PubMed

Affiliation: National Energy Technology Laboratory, United States Department of Energy 626 Cochrans Mill Road, Pittsburgh, PA, 15236, USA.

ABSTRACT
To better understand the effects of low-level fluorine in graphene-based sensors, first-principles density functional theory (DFT) with van der Waals dispersion interactions has been employed to investigate the structure and impact of fluorine defects on the electrical properties of single-layer graphene films. The results show that both graphite-2 H and graphene have zero band gaps. When fluorine bonds to a carbon atom, the carbon atom is pulled slightly above the graphene plane, creating what is referred to as a CF defect. The lowest-binding energy state is found to correspond to two CF defects on nearest neighbor sites, with one fluorine above the carbon plane and the other below the plane. Overall this has the effect of buckling the graphene. The results further show that the addition of fluorine to graphene leads to the formation of an energy band (BF) near the Fermi level, contributed mainly from the 2p orbitals of fluorine with a small contribution from the p orbitals of the carbon. Among the 11 binding configurations studied, our results show that only in two cases does the BF serve as a conduction band and open a band gap of 0.37 eV and 0.24 eV respectively. The binding energy decreases with decreasing fluorine concentration due to the interaction between neighboring fluorine atoms. The obtained results are useful for sensor development and nanoelectronics.

No MeSH data available.


Related in: MedlinePlus

The calculated total energy versus the crystal constant in graphene with and without van der Waals interactions. The data were fitted into the polynomial E(a)=B0+B1*a+B2*a2.
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fig02: The calculated total energy versus the crystal constant in graphene with and without van der Waals interactions. The data were fitted into the polynomial E(a)=B0+B1*a+B2*a2.

Mentions: As shown in Figure 1, the graphene structure can be created by cleaving parallel to the (001) surface of graphite-2 H.24 Figure 2 shows the relationship of the graphene crystal lattice constant (a=b) and the corresponding lattice total energy. For comparison, the data with and without van der Waals (VDW) dispersion interactions are plotted in the figure. As can be seen, these relationships fit well with the polynomial E(a)=B0+B1*a+B2*a2, where the coefficients B0, B1, and B2 are shown in Figure 2. Although the VDW interaction lowers the total energy by about 0.1 eV, the predicted equilibrium crystal constants from both methods are very close to each other with values of 2.46844 Å (without VDW) and 2.46837 Å (with VDW). These results indicate that the VDW interaction could affect the total energy, but does not change the structure of graphene.


Electronic Structures, Bonding Configurations, and Band-Gap-Opening Properties of Graphene Binding with Low-Concentration Fluorine.

Duan Y, Stinespring CD, Chorpening B - ChemistryOpen (2015)

The calculated total energy versus the crystal constant in graphene with and without van der Waals interactions. The data were fitted into the polynomial E(a)=B0+B1*a+B2*a2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608533&req=5

fig02: The calculated total energy versus the crystal constant in graphene with and without van der Waals interactions. The data were fitted into the polynomial E(a)=B0+B1*a+B2*a2.
Mentions: As shown in Figure 1, the graphene structure can be created by cleaving parallel to the (001) surface of graphite-2 H.24 Figure 2 shows the relationship of the graphene crystal lattice constant (a=b) and the corresponding lattice total energy. For comparison, the data with and without van der Waals (VDW) dispersion interactions are plotted in the figure. As can be seen, these relationships fit well with the polynomial E(a)=B0+B1*a+B2*a2, where the coefficients B0, B1, and B2 are shown in Figure 2. Although the VDW interaction lowers the total energy by about 0.1 eV, the predicted equilibrium crystal constants from both methods are very close to each other with values of 2.46844 Å (without VDW) and 2.46837 Å (with VDW). These results indicate that the VDW interaction could affect the total energy, but does not change the structure of graphene.

Bottom Line: The lowest-binding energy state is found to correspond to two CF defects on nearest neighbor sites, with one fluorine above the carbon plane and the other below the plane.The binding energy decreases with decreasing fluorine concentration due to the interaction between neighboring fluorine atoms.The obtained results are useful for sensor development and nanoelectronics.

View Article: PubMed Central - PubMed

Affiliation: National Energy Technology Laboratory, United States Department of Energy 626 Cochrans Mill Road, Pittsburgh, PA, 15236, USA.

ABSTRACT
To better understand the effects of low-level fluorine in graphene-based sensors, first-principles density functional theory (DFT) with van der Waals dispersion interactions has been employed to investigate the structure and impact of fluorine defects on the electrical properties of single-layer graphene films. The results show that both graphite-2 H and graphene have zero band gaps. When fluorine bonds to a carbon atom, the carbon atom is pulled slightly above the graphene plane, creating what is referred to as a CF defect. The lowest-binding energy state is found to correspond to two CF defects on nearest neighbor sites, with one fluorine above the carbon plane and the other below the plane. Overall this has the effect of buckling the graphene. The results further show that the addition of fluorine to graphene leads to the formation of an energy band (BF) near the Fermi level, contributed mainly from the 2p orbitals of fluorine with a small contribution from the p orbitals of the carbon. Among the 11 binding configurations studied, our results show that only in two cases does the BF serve as a conduction band and open a band gap of 0.37 eV and 0.24 eV respectively. The binding energy decreases with decreasing fluorine concentration due to the interaction between neighboring fluorine atoms. The obtained results are useful for sensor development and nanoelectronics.

No MeSH data available.


Related in: MedlinePlus