Abstraction of surface hydrogen by atomic H from graphane, diamond(001), diamond(111), and hydrogenated amorphous carbon (a-C:H) surfaces was studied using density-functional theory calculations in the generalized gradient approximation. Our calculations show that for each surface, the abstraction reaction is highly exothermic with a negligible activation energy barrier. The degree of exothermicity depends on the type of surface and on the local bonding environment of the site from which the H atom was abstracted. Detailed analyses of the reactions and of atomic charge densities along reaction pathways indicate a direct-impact Eley-Rideal mechanism for the abstractions.

• Received 2 April 2010

DOI:https://doi.org/10.1103/PhysRevB.82.085418