Adsorption of C₂H₄ on Stepped Cu(410) Surface: A Combined TPD, FTIR, and DFT Study

Abstract

Adsorption of ethylene (C2H4) on stepped Cu(410) surface was investigated with infrared reflection–absorption spectroscopy, temperature-programmed desorption, and density functional theory calculations. At 93 K, ethylene adsorbs molecularly on Cu(410) and forms three different π-bonded species, all of which desorb below 230 K. Even though this finding straightforwardly suggests that the three species correspond to ethylene adsorbed at the step-edge and at the two different terrace atoms, a more detailed analysis reveals this is not the case. Instead, the origin of the three species stems from the interplay between (i) strong preference of ethylene to adsorb at the step-edge, (ii) significant intermolecular repulsion between the ethylene adsorbed at the adjacent step-edge sites, and (iii) the random adsorption on the terrace sites. Recent experimental studies have suggested that ethylene is dehydrogenated on Cu(410) due to the open step-edges (Kravchuk et al. J. Phys. Chem. C 2009, 113, 20881). The present data confirm the occurrence of dehydrogenation but not the formation of a di-σ-bonded ethylene.

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

“…6(b). This conclusion is different from the previous assumption that ethylene dehydrogenate on Cu(410) should be through the long-bridge state (σ-lb-ss) [16,17]. Notice that the unimportance of the long-bridge intermediate state is consistent with the extremely low barrier from this state to the more DOI:10.1063/1674-0068/31/cjcp1805120 c ⃝2018 Chinese Physical Society stable π-s-v configuration.…”

“…Different vibrational peaks were obtained at different temperatures and surface coverages. For IRAS at 0.5 L@93 K [17] and HREELS at 1 L@145 K [15], experimental peaks can be largely understood with π-bonded ethylene adsorption. Two new peaks at 1330 and 2903 cm −1 in HREELS at 51 L@193 K [15] were previously assigned to di-σbonded ethylene.…”

“…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]. Density functional theory (DFT) calculations suggested that the di-σ-bonded configuration is a meta-stable state on Cu(410).…”

“…Density functional theory (DFT) calculations suggested that the di-σ-bonded configuration is a meta-stable state on Cu(410). A different assignment to the experimentally observed TPD peaks was also proposed [17]. Since controversies still exist for ethylene adsorption and dehydrogenation on Cu(410), a systematic study on this topic is desirable.…”

Interface Modeling for the Ab Initio Evaluation of the Water Contact Angle on a Metallic Cu(111) Surface

“…[36] For our metallic Cu surface, the orbital is delocalized, and hence, we did not consider such corrections, as in most preceding studies. [37] B. Structural model and the evaluation method…”