Electrical Control of the Chemical Bonding of Fluorine on Graphene

TL;DR

This study uses density functional theory to explore how electrical doping influences the chemical bonding of fluorine atoms on graphene, revealing a reversible transition between sp^3 and sp^2 bonding states.

Contribution

It demonstrates the electrical control of chemical bonding states of fluorine on graphene, linking doping levels to bonding configurations and lattice distortions.

Findings

Doping causes a transition from sp^3 to sp^2 bonding in fluorine-adsorbed graphene.

High electron doping restores the graphene's planar structure.

Bonding transition is explained via a simple tight binding model.

Abstract

We study the electronic structure of diluted F atoms chemisorbed on graphene using density functional theory calculations. We show that the nature of the chemical bonding of a F atom adsorbed on top of a C atom in graphene strongly depends on carrier doping. In neutral samples the F impurities induce a sp^3-like bonding of the C atom below, generating a local distortion of the hexagonal lattice. As the graphene is electron-doped, the C atom retracts back to the graphene plane and for high doping (10^14 cm^-2) its electronic structure corresponds to a nearly pure sp^2 configuration. We interpret this sp^3-sp^2 doping-induced crossover in terms of a simple tight binding model and discuss the physical consequences of this change.