Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Oxide Surfaces 1
O 49.10: Talk
Wednesday, September 7, 2022, 17:15–17:30, S053
Hydrophobic pockets on an oxide surface: In2O3(111) — Hao Chen1,2, Matthias Blatnik1,3, Michael Schmid1, Bernd Meyer4, Ulrike Diebold1, and •Margareta Wagner1,3 — 1TU Wien, Vienna, Austria — 2University of the Chinese Academy of Sciences, Beijing, China — 3CEITEC BUT, Brno, Czechia — 4FAU Erlangen-Nürnberg, Erlangen, Germany
Indium oxide, a transparent conductive oxide (TCO), is widely used in semiconductor industry but it also displays promising performance in electro- and photocatalytic reactions. In all applications, surrounding water molecules may influence chemical processes at the atomic scale, and understanding the interaction of water with In2O3 is important.
We focus on In2O3(111), which has an intrinsically large unit cell composed of a hydrophilic and a hydrophobic area. We test the reactivity of these areas by unraveling the interfacial water structures for the whole range of water coverages in UHV, from single dissociated molecules to multilayers, employing TPD, XPS, STM and AFM. Even at high coverages we clearly see hydrophilicity and hydrophobicity within the unit cell, both in experiments and calculations. Local accumulation and depletion of water is confirmed by DFT calculations and ab initio molecular dynamics (MD) simulations for ordered structures consisting of up to 18 water molecules per unit cell. This first water layer shows ordering into nanoscopic 3D water clusters separated by hydrophobic pockets. Going beyond UHV conditions, our MD simulations of a liquid layer show the robustness of the strongly hydrophobic area in the unit cell.