@article{YueMelaniKirschetal.2022,
  author    = {Yue, Yanhua and Melani, Giacomo and Kirsch, Harald and Paarmann, Alexander and Saalfrank, Peter and Campen, Richard Kramer and Tong, Yujin},
  title     = {Structure and Reactivity of a-Al2O3(0001) Surfaces: How Do Al-I and Gibbsite-like Terminations Interconvert?},
  series = {The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis},
  volume    = {126},
  journal   = {The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis},
  number    = {31},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1932-7447},
  doi       = {10.1021/acs.jpcc.2c03743},
  pages     = {13467 -- 13476},
  year      = {2022},
  abstract  = {The alpha-Al2O3(0001) surface has been extensively studied because of its significance in both fundamental research and application. Prior work suggests that in ultra-high-vacuum (UHV), in the absence of water, the so-called Al-I termination is thermodynamically favored, while in ambient, in contact with liquid water, a Gibbsite-like layer is created. While the view of the alpha- Al2O3(0001)/H2O(l) interface appears relatively clear in theory, experimental characterization of this system has resulted in estimates of surface acidity, i.e., isoelectric points, that differ by 4 pH units and surface structure that in some reports has non-hydrogen-bonded surface aluminol (Al-OH) groups and in others does not. In this study, we employed vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation to study the surface phonon modes of the differently terminated alpha-Al2O3(0001) surfaces in both UHV and ambient. We find that, on either water dosing of the Al-I in UHV or heat-induced dehydroxylation of the Gibbsite-like in ambient, the surfaces do not interconvert. This observation offers a new explanation for disagreements in prior work on the alpha-Al2O3(0001)/liquid water interface -different preparation methods may create surfaces that do not interconvert-and shows that the surface phonon spectral response offers a novel probe of interfacial hydrogen bonding structure.},
  language  = {en}
}