Adsorption and dissociation of molecular hydrogen on orthorhombic β- Mo2C and cubic δ-MoC (001) surfaces
Molybdenum carbides are increasingly used in heterogeneously catalyzed hydrogenation reactions, which imply the adsorption and dissociation of molecular hydrogen. Here a systematic density functional theory based study, including or excluding dispersion terms, concerning the interaction and stabilit...
| Authors: | , , , , |
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| Format: | article |
| Status: | Versión aceptada para publicación |
| Publication Date: | 2016 |
| Country: | España |
| Institution: | Universidad de Barcelona |
| Repository: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/112844 |
| Online Access: | https://hdl.handle.net/2445/112844 |
| Access Level: | Open access |
| Keyword: | Espectroscòpia infraroja Carburs Dissociació (Química) Hidrogenació Termodinàmica Física nuclear Infrared spectroscopy Carbides Dissociation Hydrogenation Thermodynamics Nuclear physics |
| Summary: | Molybdenum carbides are increasingly used in heterogeneously catalyzed hydrogenation reactions, which imply the adsorption and dissociation of molecular hydrogen. Here a systematic density functional theory based study, including or excluding dispersion terms, concerning the interaction and stability of H2 with cubic δ-MoC(001) and orthorhombic β-Mo2C(001) surfaces is presented. In the latter case the two possible C or Mo terminations are considered. In addition, different situations for the H covered surfaces are examined. Computational results including dispersive forces predict as essentially spontaneous dissociation of H2 on β-Mo2C(001) independently of the surface termination, whereas on δ-MoC(001) molecular hydrogen dissociation implies a small but noticeable energy barrier. Furthermore, the ab initio thermodynamics formalism has been used to compare the stability of different H coverages. Finally, core level binding energies and vibrational frequencies are presented with the aim to assist the interpretation of yet unavailable data from X-ray photoelectron and infrared spectroscopies. |
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