In situ functionalization of graphene

Abstract

While the basal plane of graphene is inert, defects in it are centers of chemical activity. An attractive application of such defects is towards controlled functionalization of graphene with foreign molecules. However, the interaction of the defects with reactive environment, such as ambient, decreases the efficiency of functionalization and makes it poorly controlled.

Here, we report a novel approach to generate, monitor with time resolution, and functionalize the defects in situ without ever exposing them to the ambient. The defects are generated by an energetic argon plasma and their properties are monitored using in situ Raman spectroscopy. We find that these defects are functional, very reactive, and strongly change their density from ≈1 × 1013 cm−2 to ≈5 × 1011 cm−2 upon exposure to air. We perform the proof of principle in situ functionalization by generating defects using the argon plasma and functionalizing them in situ using ammonia functional. The functionalization induces the n-doping with a carrier density up to 5 × 1012 cm−2 in graphene and remains stable in ambient conditions.