7 research outputs found
Adsorption and co-adsorption of CH 3 and H on flat and defective nickel (111) surfaces
We use a periodic density functional theory (DFT) code to study the
adsorption of CH3 and H, as well as their co-adsorption on a Ni(111)
surface with and without Ni ad-atom, at a surface coverage of 0.25 monolayer
(ML). We systematically investigate the site preference for CH3 and H.
Then we combine CH3 and H in many co-adsorbed configurations on both
surfaces. Methyl and hydrogen adsorption on a flat Ni(111) surface favours
the hollow site over the top site. The presence of a Ni ad-atom stabilizes
the adsorption of CH3 better than a flat surface, while hydrogen is
more stable on a flat Ni(111) surface. When H and CH3 are co-adsorbed
at nearest Ni neighbours on the (111) surface, their interaction is always
repulsive. However, the dissociative adsorption of CH4 is stabilised
when the fragments are infinitely separated. For the co-adsorbed fragments
CH3 and H, in the presence of an ad-atom, the repulsive interaction is
lowered, so that the dissociative form of CH4 is locally stable