Hydroxyl-induced wetting of metals by water at near-ambient conditions

We report different wetting properties of Cu(110) and Cu(111) at near-ambient conditions using in situ photoemission spectroscopy. At near-ambient conditions of pressure (1 Torr) and temperature (295 K), the Cu(110) surface is covered with a mixed OH and H2O layer, whereas the Cu(111) surface remains clean and adsorbate-free. We show that wetting is controlled by the presence of OH groups on the surface, acting as anchors for water adsorption. Hydroxylation of the Cu(110) surface is facilitated by a lower activation barrier for water dissociation compared to Cu(111).