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O: Fachverband Oberflächenphysik
O 60: Solid-Liquid Interfaces I: Structure and Spectroscopy
O 60.3: Talk
Wednesday, March 29, 2023, 15:30–15:45, TRE Phy
Hydrophobic pockets on the hydrophilic In2O3(111) surface — Christian Ritterhoff1, •Bernd Meyer1, Ulrike Diebold2, and Margareta Wagner2 — 1Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, FAU Erlangen-Nürnberg, Germany — 2Institute of Applied Physics, TU Wien, Austria
Clean oxide surfaces are generally hydrophilic. Water molecules anchor at undercoordinated surface cations that act as Lewis acid sites, and they are stabilized by H bonds to surface oxygens. However, for In2O3(111), DFT calculations predict a deviation from this general rule, which has been confirmed by TPD, XPS, STM and AFM experiments. In UHV, the first nine water molecules cover only a part of the unit cell. Within the H-bonded network three out of the nine water dissociate. Additional molecules pile up above the OH groups. The rest of the unit cell is unfavorable for adsorption and remains water-free, despite offering undercoordinated In and O sites. The first water layer thus shows ordering into nanoscopic 3D water clusters separated by hydrophobic pockets. Beyond UHV, our ab initio MD simulations of a liquid water layer demonstrate the robustness of the strongly hydrophobic behavior of this region in the unit cell.
[1] H. Chen, M.A. Blatnik, C.L. Ritterhoff, I. Sokolović, F. Mirabella,
G. Franceschi, M. Riva, M. Schmid, J. Čechal, B. Meyer, U. Diebold,
M. Wagner, ACS Nano, accepted, DOI: 10.1021/acsnano.2c09115