Ab initio investigations of hydrogen sorption into Bi-layer graphene via the edges

Abstract

We investigate H absorption into bi-layer graphene via the armchair edge. DFT-based total-energy calculations for H incident on pristine, rigid graphene show a reaction path with a strong H trap near the surface C atoms. In the subsurface, the negative, fluctuating potential energy indicates further H absorption becomes difficult without reconstruction. Interlayer hopping is unlikely for H stays near a graphene sheet during absorption while it may also move parallel to a C row. H desorption barriers between rows is always less than that to absorption. For subsequent H absorption on rigid H-terminated graphene edge, a large activation barrier is initially observed which is lowered by substrate atom reconstruction.