Preferential and Reversible Fluorination of Monolayer Graphene

In this work, we report the layer-dependent fluorination of n-layer graphenes by SF6 plasma treatment. For monolayer graphene, D, D', and D+G peaks of Raman spectroscopy can be clearly observed, whereas these peaks are absent for thicker n-layer graphenes (n >= 2) at the same experimental conditions. This indicates that monolayer graphene is much more susceptible to being fluorinated than thicker graphenes. These results can be well explained by larger corrugations of monolayer graphene than those of thicker graphenes. Meanwhile, the fluorination of n-layer graphenes is reversible after vacuum annealing. These studies provide useful information for exploiting the useful surface information of the fluorination of n-layer graphenes through plasma techniques.