Elucidating the water-anatase TiO₂(101) interface structure using infrared signatures and molecular dynamics

CR O'Connor and MFC Andrade and A Selloni and GA Kimmel, JOURNAL OF CHEMICAL PHYSICS, 159, 104707 (2023).

DOI: 10.1063/5.0161895

The structure and dynamics of water on solid surfaces critically affect the chemistry of materials in ambient and aqueous environments. Here, we investigate the hydrogen bonding network of water adsorbed on the majority (101) surface of anatase TiO2, a widely used photocatalyst, using polarization- and azimuth-resolved infrared spectroscopy combined with neural network potential molecular dynamics simulations. Our results show that one monolayer of water saturates the undercoordinated titanium (Ti-5c) sites, forming one-dimensional chains of molecule hydrogen bonded to surface undercoordinated bridging oxygen (O-2c) atoms. As the coverage increases, water adsorption on O-2c sites leads to significant restructuring of the water monolayer and the formation of a two-dimensional hydrogen bond network characterized by tightly bound pairs of water molecules on adjacent Ti-5c and O-2c sites. This structural motif likely persists at ambient conditions, influencing the reactions occurring there. The results reported here provide critical details of the structure of the water-anatase (101) interface that were previously hypothesized but unconfirmed experimentally.

Return to Publications page