The adsorption and dissociation of methane on cobalt surfaces: thermochemistry and reaction barriers

Abstract

The adsorption and dissociation of methane (CH₄) on a variety of cobalt (Co) surfaces have been assessed using density functional theory. The adsorption of CH_x (x = 0–4) and H species, as well as the sequential dissociation of CH₄ on Co(111), (100) and (110) surfaces, have been studied. Using the calculated adsorption energies, the preferred adsorption sites for CH_x (x = 0–4) and H species on different Co surfaces have first been located, and then the stable co-adsorption configurations of CH_x and H (x = 0–3) on these surfaces obtained. In addition the mechanism for the sequential dissociation of CH₄ on Co surfaces has been investigated and compared in terms of the thermodynamics and kinetics involved. Our results suggest that Co(100) is the preferred surface for CH₄ dissociation, both thermodynamically and kinetically, rather than (111) and (110) surfaces.