Dynamical and structural properties of adsorbed water molecules at the TiO₂ rutile-(110) surface: interfacial hydrogen bonding probed by ab-initio molecular dynamics

ABSTRACT

Ab-initio molecular dynamics (AIMD) simulations have been carried out to study a range of different and energetically-accessible adsorbed-water configurations and motifs for their vibrational and structural characteristics, in contact with rutile-(110) interfaces at 100 K. The radial pair distribution function between the titanium atoms at the interface and the hydrogen and oxygen atoms in the water monolayer show an orientation of the water molecules parallel to the surface of titania, and with hydrogen atoms pointed in the opposite direction to the surface. In some cases, a distinctive vibrational frequency region between 2500 and 3000 cm⁻¹ has also been observed, due to a strong dispersion interaction between water molecules. This behaviour is also seen in experimental studies of thin-film water coverage on TiO₂ surfaces.

GRAPHICAL ABSTRACT

KEYWORDS:

• Molecular dynamics
• titania
• water
• density functional theory
• hydrogen bonding

Acknowledgements

Pratibha Dev is acknowledged for assistance in preparing the molecular systems and for useful scientific discussions, as well as Daire O’Carroll, Sateesh Bandaru and Christian Burnham. Staff at the Irish Centre for High-End Computing (ICHEC) and HLRS are thanked for their technical assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The PRACE DECI 7 programme is thanked for access to the HLRS cluster, for the provision of high-performance computing facilities. This research has been supported by the Science Foundation Ireland (SFI)-NSFC bilateralfunding scheme [grant number SFI/17/NSFC/5229].