Adsorption of acetylene on Sn-doped Ni(111) surfaces: a density functional study.

Abstract

First-principle density functional theory calculations have been performed to investigate the adsorption of C2H2 on Ni(111) and Sn@Ni(111) at different coverages. At low coverage, the C2H2 molecule is strongly adsorbed on Ni(111) and the dissociation of the H atom is not favorable. Furthermore, the more the H atom dissociated, the more unstable the system is. However, the dissociation structure of C2H+H has the largest adsorption energy on Sn@Ni(111), indicating that the dissociation structure is more stable than molecular adsorbed C2H2. At moderate coverage, there is some repulsive interaction between two C2H2 molecules, inducing the decrease in adsorption energy. On Ni(111), the two C2H2 tend to adsorb separately, however, the dimer C4H4 has the largest adsorption energy on Sn@Ni(111). At high coverage, the trimer derivative benzene has the largest adsorption energy on both Ni(111) and Sn@Ni(111) surfaces. The adsorption energies of the formed benzene are very high on the two systems, even larger than those of three individual adsorbed C2H2.