Abstract
The adsorption modes of H2O on a Fe-terminated hematite(0 0 0 1) surface have been investigated by first principles Density Functional theory within a periodic slab model and the generalized gradient approximation. Molecular adsorption and dissociative adsorption in monolayer coverage, one H2O per surface Fe, were both considered. Five plausible orientations were studied to determine the most favorable adsorption position. Molecular adsorption is shown to have a small effect on the underlying surface structure, while hydroxylation has a strong effect on the surface geometry. Electronic densities of state calculations reveal details of these different interactions. The heterolytic dissociation, which produces two types of surface hydroxyls, is the preferable adsorption mode, being slightly favored energetically over the molecular adsorption. Homolytic dissociative adsorption, forming a single hydroxyl on surface Fe, is energetically unfavored, even though strong binding interaction (∼3 eV) is found between the OH radical and surface. Dissociative adsorption on an oxidized ferryl site was also studied to investigate suggested local reactivity enhancement.
Original language | English (US) |
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Pages (from-to) | 2426-2437 |
Number of pages | 12 |
Journal | Surface Science |
Volume | 601 |
Issue number | 12 |
DOIs | |
State | Published - Jun 15 2007 |
Keywords
- Adsorption
- Density functional
- Hematite surface
- Hydroxylation
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry