Chemical reactivity of graphene
Using atomic hydrogen as a simple model reactant, we demonstrate that the chemical reactivity of exfoliated graphene on SiO2 is strongly dependent on sample thickness: monolayers are about 2 orders of magnitude more reactive than bilayers and thicker sheets. Further, etching in monolayers is isotropic, whereas bilayers and thicker sheets are etched anisotropically. Graphene on atomically smooth mica substrates exhibits similar etching phenomena, which suggests that contrary to widely held views, substrate polarity and/or ionized impurities control the chemical reactivity of graphene, rather than substrate roughness.
Tayloring the properties of graphene by chemical modification and functionalization requires a detailed understanding of the factors controlling the chemical reactivity of graphene. Our findings are of great relevance for opening a band gap by chemical functionalization, charge-transfer doping, patterning graphene by anisotropic etching, and interfacing graphene with other materials.
Contact Georgi Diankov (gdiankov@) or Michael Neumann (m.neumann@) for more information.