Fluorine absorption on single and bilayer graphene: Role of sublattice and layer decoupling

TL;DR

This study uses ab-initio DFT calculations to explore how fluorine atoms interact with single and bilayer graphene, revealing the importance of sublattice positioning and layer decoupling effects on fluorination stability.

Contribution

It provides new insights into fluorine adsorption preferences on graphene's sublattices and demonstrates electronic decoupling in bilayer systems upon fluorination.

Findings

F atoms prefer same sublattice chemisorption at low coverage

Large F coverage (up to C4F) is more stable when F atoms occupy different sublattices

Electronic decoupling occurs when only one layer in bilayer graphene is fluorinated

Abstract

The fluorination of mono- and bi-layer graphene have been studied by means of ab-initio DFT calculations. The stability of CF$_x$ systems are found to depend on both the F coverage and on the position of the F atoms regarding the C sublattices. When F atoms is chemisorbed to C atoms belonging to the same sublattice, low coverage is preferred. Otherwise, large F coverable is more stable (up to C$_4$F). The difference of charge distribution between the two carbon sublattices explains this finding that is confirmed by the analysis of the diffusion barriers. Binding energy of F on bi-layer systems is also computed slightly smaller than on monolayer and electronic decoupling is observed when only one of the layer is exposed to fluorine.