Ethene Adsorption and Decomposition on the Cu(410) Surface

Abstract

The influence of open steps on the surface properties is shown by investigating the interaction of molecular ethene with Cu(410). We find a surprisingly low-temperature, site-selective chemistry at the strongly under-coordinated step sites. Ethene bonds either in a π-bonded or in a di-σ-bonded state or undergoes complete dehydrogenation. All pathways involve the low-coordination sites at the step, since the first species is partially stabilized with respect to low-Miller-index surfaces, while the other two are observed only on Cu(410). When annealing the surface, dehydrogenation and transformation into the di-σ-bonded moiety proceed, both processes being favored by faster heating rates. The so-generated carbon (presumably C2 admolecules) decorates the step edges, thereby blocking the active sites for subsequent dissociation and permitting only π-bonding of ethene. The dipole loss of carbon disappears in high-resolution electron energy loss spectroscopy when annealing to room temperature, indicating that carbon moves to more coplanar or even to subsurface sites where it still influences the surface chemistry. The surface reactivity is recovered when heating the crystal to 900 K since C dissolves then deep enough into the bulk.

Iron phthalocyanine on Cu(111): Coverage-dependent assembly and symmetry breaking, temperature-induced homocoupling, and modification of the adsorbate-surface interaction by annealing

“…The same kind of scheme is known to occur under a certain condition for smaller doubleand triple-bonded molecules at transition metal surfaces and has, e.g., been observed for ethene on a stepped Cu(410) surface. 40 It has not been observed previously for a doublebonded hydrocarbon on a flat Cu(111) surface, though, 41 the reason presumably being that the barrier towards the second chemisorption state is too unfavorable. Here, we find spectroscopic evidence for a transfer of the FePc adsorbates into such a second chemisorptive state by annealing, possibly as a result of a changed barrier to desorption.…”

Theoretical study of adsorption and dehydrogenation of C2H4 on Cu(410)

“…Recently, the adsorption of ethylene on Cu(410) has been intensively investigated [14][15][16]. At low temperature and low coverage, ethylene binds with the Cu(410) surface with a π-bonded configuration.…”

“…At low temperature and low coverage, ethylene binds with the Cu(410) surface with a π-bonded configuration. At the same time, a di-σ-bonded adsorption configuration was suggested based on HREELS spectra at higher surface temperature and/or higher surface coverage [14][15][16]. The di-σ-bonded ethylene was also proposed to be the precursor of the dehydrogenation reaction [15,16].…”

“…At the same time, a di-σ-bonded adsorption configuration was suggested based on HREELS spectra at higher surface temperature and/or higher surface coverage [14][15][16]. The di-σ-bonded ethylene was also proposed to be the precursor of the dehydrogenation reaction [15,16]. XPS and HREELS experiments suggested that the reactive site of dehydrogenation is located at step edges [15].…”

“…The di-σ-bonded ethylene was also proposed to be the precursor of the dehydrogenation reaction [15,16]. XPS and HREELS experiments suggested that the reactive site of dehydrogenation is located at step edges [15]. The di-σ-bonded ethylene based dehydrogenation picture, however, was challenged by a recent study combining experimental and computational characterizations [17].…”