Near-Earth Asteroids (NEAs) are excellent laboratories for processes that affect airless body surfaces. S-complex (including V-type) NEAs were not expected to contain OH/H2O on their surfaces because they formed in the anhydrous regions of the solar system and their surface temperatures are high enough to remove these volatiles. However, a 3
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The microscopic mechanisms underpinning the spontaneous surface passivation of metals from ubiquitous water have remained largely elusive. Here, using in situ environmental electron microscopy to atomically monitor the reaction dynamics between aluminum surfaces and water vapor, we provide direct experimental evidence that the surface passivation results in a bilayer oxide film consisting of a crystalline-like Al(OH)3top layer and an inner layer of amorphous Al2O3. The Al(OH)3layer maintains a constant thickness of ~5.0 Å, while the inner Al2O3layer grows at the Al2O3/Al interface to a limiting thickness. On the basis of experimental data and atomistic modeling, we show the tunability of the dissociation pathways of H2O molecules with the Al, Al2O3, and Al(OH)3surface terminations. The fundamental insights may have practical significance for the design of materials and reactions for two seemingly disparate but fundamentally related disciplines of surface passivation and catalytic H2production from water.
more » « less- Award ID(s):
- 1905572
- NSF-PAR ID:
- 10535246
- Publisher / Repository:
- Science
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 9
- Issue:
- 44
- ISSN:
- 2375-2548
- Page Range / eLocation ID:
- edah5565
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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