Ab initio studies of hydrogen adatoms on bilayer graphene

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Authors

Mapasha, Refilwe Edwin
Ukpong, Aniekan M.
Chetty, Nithaya

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American Physical Society

Abstract

We present a comparative density functional study of the adsorption of hydrogen on bilayer graphene. Six different exchange-correlation functionals are employed to explore the possible configurations of hydrogen ad- sorption at 50% coverage. Using the four variants of the non-local van derWaals density functional, we identify three distinct competing configurations that retain the coupled bilayer structure at 0 K. One of the configurations undergoes a spontaneous transformation from hexagonal to tetrahedral structure, under hydrogenation, with heat of formation ranging between -0.03 eV (vdW-DF) and -0.37 eV (vdW-DFC09x). This configuration has a finite band gap of around 3 eV, whereas all other competing configurations are either semi-metallic or metallic. We also find two unique low-energy competing configurations of decoupled bilayer graphene, and therefore suggest the possibility of graphene exfoliation by hydrogen intercalation.

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Keywords

Hydrogen adatoms, Bilayer graphene

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Citation

Mapasha, RE, Ukpong, AM & Chetty, N 2012, 'Ab initio studies of hydrogen adatoms on bilayer graphene', Physical Review B, vol. 85, no. 20.