Surface diffraction study of the hydrated hematite surface
| Autor: | Gordon E. Brown, Glenn A. Waychunas, Kunaljeet Tanwar, Cynthia S. Lo, Anne M. Chaka, Donald A. Walko, Jeffrey G. Catalano, Thomas P. Trainor, Peter J. Eng |
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| Rok vydání: | 2007 |
| Předmět: |
Aqueous solution
Chemistry Oxide Protonation Surfaces and Interfaces Hematite Condensed Matter Physics Surfaces Coatings and Films chemistry.chemical_compound Crystallography visual_art X-ray crystallography Materials Chemistry visual_art.visual_art_medium Reactivity (chemistry) Density functional theory Stoichiometry |
| Zdroj: | Surface Science. 601:460-474 |
| ISSN: | 0039-6028 |
| Popis: | The structure of the hydroxylated a-Fe2O3ð1 102 Þ surface prepared via a wet chemical and mechanical polishing (CMP) procedure was determined using X-ray crystal truncation rod diffraction. The experimentally determined surface model was compared with theoretical structures developed from density functional theory (DFT) calculations to identify the most likely protonation states of the surface (hydr)oxo moieties. The results show that the hydroxylated CMP-prepared surface differs from an ideal stoichiometric termination due to vacancies of the near surface bulk Fe sites. This result differs from previous ultra high vacuum studies where two stable terminations were observed: a stoichiometric (1 · 1) termination and a partially reduced (2 · 1) reconstructed surface. The complementary DFT studies suggest that hydroxylated surfaces are thermodynamically more stable than dehydroxylated surfaces in the presence of water. The results illustrate that the best fit surface model has predominantly three types of (hydr)oxo functional groups exposed at the surface at circumneutral pH: Fe–OH2 ,F e 2–OH, and Fe3–O and provide a structural basis for interpreting the reactivity of model iron-(hydr)oxide surfaces under aqueous conditions. � 2006 Elsevier B.V. All rights reserved. |
| Databáze: | OpenAIRE |
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