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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 fluorine binding sites. The first fluorine binds on the F1 site, the second fluorine binds on site A, B, C, D, or E to form five cases of 2 F-adsorbed graphene. For each case, the fluorine atoms may bind on either the same or opposite side of the graphene plane to produce two different configurations.
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fig03: The fluorine binding sites. The first fluorine binds on the F1 site, the second fluorine binds on site A, B, C, D, or E to form five cases of 2 F-adsorbed graphene. For each case, the fluorine atoms may bind on either the same or opposite side of the graphene plane to produce two different configurations.

Mentions: In order to reach the experimentally observed F-adsorption level of 2 %, a 7×7×1 surface was generated from graphite-2 H crystal to represent graphene in our following calculations, as shown in Figure 1. Figure 3 shows the 1 F- and 2 F-adsorbed graphene configurations which are used in this study. For two fluorine atoms binding on carbon of graphene (with the F-bonded carbon designated as CF), there are many possible binding sites. Binding the first fluorine directly over a carbon atom (F1 site in Figure 3) produces what is referred to as a CF defect. For the second F-binding site (CF defect), one of five different cases (A, B, C, D, and E), as shown in Figure 3, was chosen. For each case, the two fluorine atoms can be on the same or opposite side of the graphene plane. This leads to two different configurations for each of the five cases.


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 fluorine binding sites. The first fluorine binds on the F1 site, the second fluorine binds on site A, B, C, D, or E to form five cases of 2 F-adsorbed graphene. For each case, the fluorine atoms may bind on either the same or opposite side of the graphene plane to produce two different configurations.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig03: The fluorine binding sites. The first fluorine binds on the F1 site, the second fluorine binds on site A, B, C, D, or E to form five cases of 2 F-adsorbed graphene. For each case, the fluorine atoms may bind on either the same or opposite side of the graphene plane to produce two different configurations.
Mentions: In order to reach the experimentally observed F-adsorption level of 2 %, a 7×7×1 surface was generated from graphite-2 H crystal to represent graphene in our following calculations, as shown in Figure 1. Figure 3 shows the 1 F- and 2 F-adsorbed graphene configurations which are used in this study. For two fluorine atoms binding on carbon of graphene (with the F-bonded carbon designated as CF), there are many possible binding sites. Binding the first fluorine directly over a carbon atom (F1 site in Figure 3) produces what is referred to as a CF defect. For the second F-binding site (CF defect), one of five different cases (A, B, C, D, and E), as shown in Figure 3, was chosen. For each case, the two fluorine atoms can be on the same or opposite side of the graphene plane. This leads to two different configurations for each of the five cases.

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