Study of translational, librational and intra-molecular motion of adsorbed liquid water monolayers at various TiO₂ interfaces

Abstract

Equilibrium classical molecular dynamics (MD) simulations have been performed to investigate the vibrational motion of water in contact with rutile-(110), rutile-(100), rutile-(001), anatase-(101) and anatase-(001) surfaces at room temperature (300 K). The vibrational density of states (VDOS) of the first adsorbed monolayer of liquid water has been analysed for each surface. These have been compared with reported experimental INS values involving rutile and anatase polymorph surfaces, along with ab initio MD results. It is observed that good qualitative agreement is obtained for the rutile-(110) and the anatase-(101) surfaces with the corresponding experimental VDOS. A significant contribution from librational dynamics is found for planar rutile surfaces, but no such demarcation is seen in the experimental VDOS.

Keywords:

• molecular dynamics
• titania
• water
• vibrational motion

Acknowledgements

The authors acknowledge useful conversations with Dr. Damian Mooney and Professor Nancy Ross. This material is based upon work supported by the Science Foundation Ireland (SFI) under Grant No. [07/SRC/B1160], in addition to the Irish Research Council for Science, Engineering and Technology. We thank SFI and the Irish Centre for High-End Computing for the provision of high-performance computing facilities. The authors acknowledge the support of industry partners to the Cluster: SolarPrint, Celtic Catalysts, Glantreo, Mainstream Renewable Power, Kingspan and SSE Renewables.