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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 density of states of 1 F-adsorbed graphene.
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fig08: The calculated density of states of 1 F-adsorbed graphene.

Mentions: Figure 8 shows the calculated TDOS and PDOS of 1 F-adsorbed graphene. Compared to the pure graphene with zero band gap shown in Figure 7 b, when fluorine binds with the carbon of graphene to form the CF defect, the electronic structure is changed. As shown in Figure 4, the optimized F−CF bond length is 1.575 Å, which indicates the bonding between fluorine and graphene is very strong, with a binding energy of 2.071 eV. Around the Fermi-level EF there is a new band which is mainly contributed by p orbitals of fluorine atom. From the PDOS of carbon and fluorine shown in Figure 8, one can see that the contributions from the p orbitals of carbon are located below the Fermi level, while a fluorine band (BF), with a bandwidth of 0.36 eV, lies near the Fermi level and is partially occupied. Below the BF, there is a small gap EVBF with a value of 0.12 eV, while above the BF, there is a gap Eg with a value of 0.378 eV between BF and the conduction band (CB).


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 density of states of 1 F-adsorbed graphene.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig08: The calculated density of states of 1 F-adsorbed graphene.
Mentions: Figure 8 shows the calculated TDOS and PDOS of 1 F-adsorbed graphene. Compared to the pure graphene with zero band gap shown in Figure 7 b, when fluorine binds with the carbon of graphene to form the CF defect, the electronic structure is changed. As shown in Figure 4, the optimized F−CF bond length is 1.575 Å, which indicates the bonding between fluorine and graphene is very strong, with a binding energy of 2.071 eV. Around the Fermi-level EF there is a new band which is mainly contributed by p orbitals of fluorine atom. From the PDOS of carbon and fluorine shown in Figure 8, one can see that the contributions from the p orbitals of carbon are located below the Fermi level, while a fluorine band (BF), with a bandwidth of 0.36 eV, lies near the Fermi level and is partially occupied. Below the BF, there is a small gap EVBF with a value of 0.12 eV, while above the BF, there is a gap Eg with a value of 0.378 eV between BF and the conduction band (CB).

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