Water Interactions with Terminal Hydroxyls on TiO2(110)

A combination of scanning tunneling microscopy and density functional theory has been used to investigate the interactions between water molecules and terminal hydroxyls (OH t ’s) adsorbed on the TiO 2 (110) surface at 300 K. We show that OH t ’s have a significant effect on the water reactivity. Two distinctive reaction pathways are unraveled depending on the whether H 2 O and OH t are on the same or adjacent Ti rows. The underlying reaction mechanisms involve proton transfer from H 2 O to OH t leading to the formation of new H 2 O molecules, accompanied by O scrambling and along- or across-row apparent motion of OH t ’s.