Water on titanium dioxide surface: a revisiting by reactive molecular dynamics simulations

Area of Science:

• Surface science
• Materials science
• Computational chemistry

Background:

• Surface water behavior on titanium dioxide (TiO2) is critical for its photocatalytic and biomedical applications.
• Understanding adsorption and dissociation characteristics is key to optimizing TiO2 material performance.

Purpose of the Study:

• To investigate water interactions with five different TiO2 surfaces using molecular dynamics simulations.
• To determine the varying reactivities of TiO2 surfaces towards water dissociation.

Main Methods:

• Molecular dynamics (MD) simulations.
• ReaxFF reactive force field.
• Analysis of water adsorption and dissociation on different TiO2 crystal facets.

Main Results:

• TiO2 surfaces exhibit distinct water dissociation reactivities: rutile (011) > TiO2-B (100) > anatase (001) > rutile (110).
• No water dissociation was observed on the TiO2-B (001) surface.
• Dissociation leads to Ti-OH and O-H functional groups, altering near-surface water molecule orientation and hydrogen bonding networks.

Conclusions:

• Surface reactivity significantly influences water behavior on TiO2, affecting surface chemistry.
• The formation of hydroxyl groups on reactive surfaces enhances hydrogen bonding, impacting water configurations.
• Non-reactive surfaces show weaker interactions with water, with molecules positioned further from the surface.