Cooperative Formation of Long-Range Ordering in Water Ad-layers on Fe3 O4 (111) Surfaces.

The initial stages of water adsorption on magnetite Fe3 O4 (111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection-absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fetet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self-assembles into an ordered (2×2) structure. Water ad-layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen-bonding network.