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Atomic‐Scale Studies of Fe 3 O 4 (001) and TiO 2 (110) Surfaces Following Immersion in CO 2 ‐Acidified Water
- Source :
- ChemPhysChem
- Publication Year :
- 2020
- Publisher :
- Wiley, 2020.
-
Abstract
- Difficulties associated with the integration of liquids into a UHV environment make surface-science style studies of mineral dissolution particularly challenging. Recently, we developed a novel experimental setup for the UHV-compatible dosing of ultrapure liquid water, and studied its interaction with TiO2 and Fe3O4 surfaces. Here, we describe a simple approach to vary the pH through the partial pressure of CO2 (pCO2) in the surrounding vacuum chamber, and use this to study how these surfaces react to an acidic solution. The TiO2(110) surface is unaffected by the acidic solution, except for a small amount of carbonaceous contamination. The Fe3O4(001)-(rt2 x rt2)R45 surface begins to dissolve at a pH 4.0-3.9 (pCO2 = 0.8-1 bar) and, although it is significantly roughened, the atomic-scale structure of the Fe3O4(001) surface layer remains visible in scanning tunneling microscopy (STM) images. X-ray photoelectron spectroscopy (XPS) reveals that the surface is chemically reduced, and contains a significant accumulation of bicarbonate (HCO3-) species. These observations are consistent with Fe(II) being extracted by bicarbonate ions, leading to dissolved iron bicarbonate complexes (Fe(HCO3)2), which precipitate onto the surface when the water evaporates.
- Subjects :
- Materials science
Bicarbonate
Inorganic chemistry
FOS: Physical sciences
02 engineering and technology
010402 general chemistry
01 natural sciences
law.invention
Ion
chemistry.chemical_compound
X-ray photoelectron spectroscopy
law
Surface layer
Physical and Theoretical Chemistry
Dissolution
Condensed Matter - Materials Science
Materials Science (cond-mat.mtrl-sci)
Partial pressure
021001 nanoscience & nanotechnology
6. Clean water
Atomic and Molecular Physics, and Optics
0104 chemical sciences
chemistry
Scanning tunneling microscope
0210 nano-technology
Bar (unit)
Subjects
Details
- ISSN :
- 14397641 and 14394235
- Volume :
- 21
- Database :
- OpenAIRE
- Journal :
- ChemPhysChem
- Accession number :
- edsair.doi.dedup.....6578cc8536db4aefc6395ab58415b47c