Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) ‐ Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer.

Abstract

Understanding the surface site preference for single adsorbates, the interactions between adsorbates, how these interactions affect surface site specificity in adsorption and perturb the electronic states of surfaces is important for rationalizing the structure of interfaces and the growth of surface products. Herein, using density functional theory (DFT) calculations, we investigated the adsorption of H S, HS and, S onto Cu(110). The surface site specificity observed for single adsorbates can be largely affected by the presence of other adsorbates, especially S that can affect the adsorption of other species even at distances of 13 Å. The large supercell employed with a surface periodicity of (6×6) allowed us to safely use the Helmholtz method for the determination of the dipole of the surface-adsorbate complex at low adsorbate coverages. We found that the surface perturbation induced by S can be explained by the charge transfer model, H S leads to a perturbation of the surface that arises mostly from Pauli exclusion effects, whereas HS shows a mix of charge transfer and Pauli exclusion effects. These effects have a large contribution to the long range adsorbate-adsorbate interactions observed. Further support for the long range adsorbate-adsorbate interactions are the values of the adsorption energies of adsorbate pairs that are larger than the sum of the adsorption energies of the single adsorbates that constitute the pair. This happens even for large distances and thus goes beyond the H-bond contribution for the H-bond capable adsorbate pairs. Exploiting this knowledge we investigated two models for describing the first stages of growth of a layer of S-atoms at the surface: the formation of islands versus the formation of more homogeneous surface distributions of S-atoms. We found that for coverages lower than 0.5 ML the S-atoms prefer to cluster as islands that evolve to stripes along the [1 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mn>1</mml:mn><mml:mo>‾</mml:mo></mml:mover></mml:math> 0] direction with increasing coverage. At 0.5 ML a homogeneous distribution of S-atoms becomes more stable than the formation of stripes. For the coverage equivalent to 1 ML, the formation of two half-monolayers of S-atoms that disrupt the Cu-Cu bonds between the first and second layer is more favorable than the formation of 1 ML homogeneous coverage of S-atoms. Here the S-Cu bond distances and geometries are reminiscent of pyrite, covellite, and to some extent chalcocite. The small energy difference of ≈0.1 eV that exists between this structure and the formation of 1 ML suggests that in a real system at finite temperature both structures may coexist leading to a structure with even lower symmetry.

The first stages of oxide growth at the low index Al surfaces (100), (110), (111): clusters and stripes vs. homogeneous growth

“…20,21,30 This approach is valid to a large extent because for non-neighboring sites, even though the adsorbate-adsorbate interactions can change the reaction energies considerably and be long ranged, reaching several Å distance, the long range adsorbate-adsorbate interactions seldom change the preferences for binding sites. 58,59 These effects have been studied in our previous works and will not be discussed here with further detail For the cluster models where the O-atoms are placed at neighboring sites, however, we observed that for many of the cases the initial guesses based on the preferred binding sites for single O-atoms led to other geometries after optimization. It became clear that the co-adsorption of O-atoms affects their preferences for the surface binding sites.…”

Segregation of P and S Impurities to A Σ9 Grain Boundary in Cu

“…Density functional theory (DFT) calculations of the segregation or absorption of S and P to the Σ9 GB of fcc Cu were performed with the Vienna ab initio simulation package (VASP 5.4.1) [19] with the Perdew-Burke-Ernzerhof [20] (PBE) exchange-correlation functional with pseudopotentials of the projector augmented wave [21,22] (PAW) type. The PBE functional showed good accuracy for describing the interactions between p-block elements with the bulk and surfaces of Cu [2,[23][24][25][26]. For all calculations, a plane wave cutoff of 460 eV and a k-point mesh of (7 × 9 × 3) in the Monkhorst-Pack sampling scheme were employed [27].…”

Interactions between glucosides of the tip of the S1 subunit of SARS-CoV-2 spike protein and dry and wet surfaces of CuO and Cu—A model for the surfaces of coinage metals

“…The bare wet surfaces of CuO and Cu were prepared for the study of adsorption of the glucoside monomers by the subsequent creation of 1 ML of adsorbed H 2 O on the initially dry surfaces, generating structures similar to those reported in previous works [30] , [37] , [38] , [39] . The difference between the current case and the cited works is that significantly larger supercells are here employed.…”

“…The difference between the current case and the cited works is that significantly larger supercells are here employed. The perfect Cu(110) surface can be used to simulate molecular adsorption onto real Cu surfaces with good accuracy because it contains 5 symmetrically non-equivalent binding sites [38] . These different coordination sites can to a good extent mimic the role of some point defects in molecular adsorption [39] , [55] .…”

“…The electronic structure calculation methods here employed have been previously extensively tested and benchmarked in varied studies of adsorption on pure and oxidized Cu surfaces as well as hydroxylated Cu surfaces [37] , [38] , [39] . DFT calculations were performed with the Vienna ab initio simulation package [40] (VASP 5.4.4) employing the exchange-correlation functional by Perdew-Burke-Ernzerhof, PBE (Refs [41] , [42] .)…”