Electronic structure and reactivity of defect MoS2 II. Bonding and activation of hydrogen on surface defect sites and clusters
| Autor: | Kamil Klier, Jeffery A. Spirko, Abigail M. Oelker, Michael L. Neiman |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Hydrogen
chemistry.chemical_element Surfaces and Interfaces Electronic structure Condensed Matter Physics Surfaces Coatings and Films Crystallography chemistry.chemical_compound chemistry Atomic orbital Molybdenum Materials Chemistry Cluster (physics) Molecule Density functional theory Atomic physics Molybdenum disulfide |
| Zdroj: | Surface Science. 572:191-205 |
| ISSN: | 0039-6028 |
| Popis: | The defects of MoS 2 were investigated for activation of hydrogen using density functional theory by modeling the molybdenum disulfide monomer, small clusters, and edges in periodic structures. Attachment of H 2 to the MoS 2 molecule was studied in detail, and several structures were found by optimization methods. A dihydride with the hydrogen atoms far apart was determined to be most stable. In this configuration, the σ* orbital of the H 2 mixes with the 4d orbitals of Mo and 3p orbitals of S to achieve the hydrogen activation. The less stable η 2 hydrogen configuration has the H–H bond slightly stretched with the H atoms equidistant from the Mo center. A triangular Mo 7 S 14 cluster provides a small model with edges resembling those of the cut MoS 2 sheets. On this cluster, both the η 2 hydrogen and the dihydride occur. In the periodic system, atomic hydrogen adsorbs in stable positions on the MoS 2 edges either bridging between Mo atoms or attached to Mo or S atoms. The frequencies of H vibrations are found to be highly dependent on the atom(s) to which the hydrogen is attached, and range from 1223 cm −1 for a position bridging two Mo atoms, to about 1860 cm −1 for Mo–H bonds, to about 2500 cm −1 for S–H bonds. In addition, some configurations with molecular H 2 adsorption on the edges were investigated, and the H–H frequency of 2999 cm −1 was calculated for a dihydride configuration. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect