Low-temperature adsorption of H2S on Ag(111)

Abstract

H 2 S forms a rich variety of structures on Ag(111) at low temperature and submonolayer coverage. The molecules decorate step edges, exist as isolated entities on terraces, and aggregate into clusters and islands, under various conditions. One type of island exhibits a (×)R25.3° unit cell. Typically, molecules in the clusters and islands are separated by about 0.4 nm, the same as the S-S separation in crystalline H 2 S. Density functional theory indicates that hydrogen-bonded clusters contain two types of molecules. One is very similar to an isolated adsorbed H 2 S molecule, with both S-H bonds nearly parallel to the surface. The other has a S-H bond pointed toward the surface. The potential energy surface for adsorption and diffusion is very smooth. KeywordsAmes Laboratory, adsorption, density functional theory, diffusion, hydrogen bonds, intermolecular forces, island structure, molecular clusters, potential energy surfaces, silver, sulphur compounds H 2 S forms a rich variety of structures on Ag͑111͒ at low temperature and submonolayer coverage. The molecules decorate step edges, exist as isolated entities on terraces, and aggregate into clusters and islands, under various conditions. One type of island exhibits a ͑ ͱ 37ϫ ͱ 37͒R25.3°unit cell.Typically, molecules in the clusters and islands are separated by about 0.4 nm, the same as the S-S separation in crystalline H 2 S. Density functional theory indicates that hydrogen-bonded clusters contain two types of molecules. One is very similar to an isolated adsorbed H 2 S molecule, with both S-H bonds nearly parallel to the surface. The other has a S-H bond pointed toward the surface. The potential energy surface for adsorption and diffusion is very smooth.

Investigation on adsorption and decomposition of H2S on Pd (1 0 0) surface: A DFT study

“…In all calculations, for the most stable co-adsorption configuration on Pd (1 0 0) surfaces, the initial structures were considered to be that the relative species are positioned at the adjacent and preferred adsorption sites, respectively [38][39][40][41]. For example, for the most stable co-adsorbed configuration of HS/H on the Pd (1 0 0) surface, the initial co-adsorbed structure is that HS and H are placed on the two adjacent hollow sites, as presented in Fig.…”

“…Tremendous efforts have been devoted to ascertain the adsorption and decomposition mechanism of H 2 S on the surfaces of a myriad of metal catalysts, such as Fe [21][22][23][24][25], Cu [26][27][28], Pd [17,[29][30][31][32], Ge [33], Ru [34], Ni [31,35], Au [31,36], Ir [31], Ag [31,37], Pt [38], W [39], and Mo [40]. The dissociation of H 2 S on these surfaces was usually described as a facile process with low energy barrier.…”

Communication: Structure, formation, and equilibration of ensembles of Ag-S complexes on an Ag surface

“…20 The Ag(111) sample (MaTecK GmbH) was cleaned by repeated cycles of Ar + sputtering and annealing at ∼670 K. S 2 (gas) was generated from a solid-state electrochemical Ag|AgI|Ag 2 S|Pt cell in situ. 21 Sulfur coverage was determined by comparing STM image areas with prior data, in which Auger electron spectroscopy was implemented as an absolute measure.…”

Long-Range Displacive Reconstruction of Au(110) Triggered by Low Coverage of Sulfur

“…21 Details have been given elsewhere. 7,22 Cutoff energy for the plane-wave basis set was 280 eV. For each supercell, we used a minimal k-points grid that corresponded to the (12 × 8 × 1) grid for the primitive unit cell as closely as possible.…”

“…On the contrary, this regime is rich with unexpected phenomena, including new ordered structures 5 and stoichiometric surface−metal complexes. 6,7 In this paper, we report an exploration of the interaction of sulfur with Au(110). No complexes form in this system (under the conditions of our experiments), but we find an intriguing condensation of sulfur adatoms at low coverage into a surface reconstruction.…”