Chemical reactivity of graphene



Left: (top) tapping-mode AFM image of monolayer and multilayer graphene on SiO2 after hydrogen plasma treatment at 500 °C for 10 min, (bottom) dependence of etch rates on furnace temperature. Right: (top) AFM topography and phase shift images of marked area, showing circular etch pits in monolayer graphene; (bottom) AFM topography images of hexagonal etch pits in multilayer graphene and thick graphite flakes.

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.

References

  1. Georgi Diankov, Michael Neumann, and David Goldhaber-Gordon, "Extreme Monolayer-Selectivity of Hydrogen-Plasma Reactions with Graphene" ACS Nano 7, 1324 (2013) [See related Stanford Report]. Supplementary info
Contact Georgi Diankov (gdiankov@) or Michael Neumann (m.neumann@) for more information.