Impact of Ti Incorporation on Hydroxylation and Wetting of Fe 3 O 4
Understanding the interaction of water with compositionally tuned metal oxides is central to exploiting their unique catalytic and magnetic properties. However, processes such as hydroxylation, wetting, and resulting changes in electronic structure at ambient conditions are challenging to probe in situ. Here, we examine the hydroxylation and wetting of Fe(3-x)TixO4 epitaxial films directly using ambient pressure X-ray photoelectron spectroscopy under controlled relative humidity. Fe2+ formation promoted by Ti4+ substitution for Fe3+ increases with hydroxylation, commensurate with a decrease in the surface work function or change in the surface dipole. The incorporation of small amounts of Ti (x=0.25) as a bulk dopant dramatically impacts hydroxylation, in part due to surface segregation, leading to coverages closer to that of TiO2 than Fe3O4. However, the Fe(3-x)TixO4 compositional series shows a similar affinity for water physisorption, which begins at notably lower relative humidity than on TiO2. The findings suggest that relative humidity rather than surface hydroxyl density controls wettability. Studies of this kind directly relate to rational design of doped magnetite into more active catalysts for UV/Fenton degradation, the adsorption of contaminants, and the development of spin filters.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1390440
- Report Number(s):
- PNNL-SA-128589; 49381; KC0302060
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 121, Issue 35; ISSN 1932-7447
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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