Atomically Resolved Imaging of Highly Ordered Alternating Fluorinated Graphene

TL;DR

This study uses advanced electron microscopy to demonstrate that C2F chair is a stable, highly ordered fluorinated graphene derivative with long-range order, confirming theoretical predictions and providing a method to distinguish fluorinated phases.

Contribution

The paper provides the first atomic-scale imaging of C2F chair graphene derivative, confirming its stability and order, and introduces electron diffraction as a quick identification method.

Findings

C2F chair is a stable, ordered graphene derivative.

Long-range order extends over domains of at least 0.16 square micrometers.

Electron diffraction distinguishes fluorinated graphene phases.

Abstract

One of the most desirable goals of graphene research is to produce ordered 2D chemical derivatives of suitable quality for monolayer device fabrication. Here we reveal, by focal series exit wave reconstruction, that C2F chair is a stable graphene derivative and demonstrates pristine long-range order limited only by the size of a functionalized domain. Focal series of images of graphene and C2F chair formed by reaction with XeF2 were obtained at 80 kV in an aberration-corrected transmission electron microscope. EWR images reveal that single carbon atoms and carbon-fluorine pairs in C2F chair alternate strictly over domain sizes of at least 150 nm^2 with electron diffraction indicating ordered domains >/= 0.16 square micrometer. Our results also indicate that, within an ordered domain, functionalization occurs on one side only as theory predicts. Additionally we show that electron diffraction provides a quick and easy method for distinguishing between graphene, C2F chair and fully fluorinated stoichiometric CF 2D phases.