Details

Autor(en) / Beteiligte

• Mirabella, Francesca
• Balajka, Jan
• Pavelec, Jiri
• Göbel, Markus
• Kraushofer, Florian
• Schmid, Michael
• Parkinson, Gareth S.
• Diebold, Ulrike

Titel

Atomic‐Scale Studies of Fe 3 O 4 (001) and TiO 2 (110) Surfaces Following Immersion in CO 2 ‐Acidified Water

Ist Teil von

• Chemphyschem, 2020-08, Vol.21 (16), p.1788-1796

Erscheinungsjahr

2020

Quelle

Wiley-Blackwell Full Collection

Beschreibungen/Notizen

• 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 TiO 2 and Fe 3 O 4 surfaces. Herein, we describe a simple approach to vary the pH through the partial pressure of CO 2 ( ) in the surrounding vacuum chamber and use this to study how these surfaces react to an acidic solution. The TiO 2 (110) surface is unaffected by the acidic solution, except for a small amount of carbonaceous contamination. The Fe 3 O 4 (001)‐( × )R45° surface begins to dissolve at a pH 4.0–3.9 ( =0.8–1 bar) and, although it is significantly roughened, the atomic‐scale structure of the Fe 3 O 4 (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 (HCO 3 − ) species. These observations are consistent with Fe(II) being extracted by bicarbonate ions, leading to dissolved iron bicarbonate complexes (Fe(HCO 3 ) 2 ), which precipitate onto the surface when the water evaporates.