Atomic Hydrogen Diffusion on Doped and Chemically
Modified Graphene
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Abstract
To explore hydrogen
mobility on graphene, density functional calculations
are used to determine the magnitude of binding energy versus the diffusion
barrier for graphene, considering the effects of hole and electron
doping, B and N substitutional dopants, and oxygen heteroatoms. Although
C–H binding energy and the barrier for chemical diffusion are
not correlated, the binding energy of H in the lowest energy site
on top of a C atom correlates with the binding energy of H over a
“bridge” C–C bond, which is the transition state
for chemical diffusion. Using this framework, we demonstrate that
both B substitutionally doped graphene and hydoxylated graphene have
the potential to simultaneously meet thermodynamic and kinetic constraints
for reversible room-temperature hydrogenation. The constraints demonstrate
that reversible room-temperature hydrogenation is possible only when
H diffuses in a chemically bound state