Influence of surface polarity on water dynamics at the water/rutile TiO₂(110) interface

Abstract

We report molecular dynamics (MD) simulations of the water/clean rutile TiO2 (110) interface using polarizable and non-surface polarity force field models. The effect of surface polarity on the water dynamics near the TiO2(110) surface is addressed, specifically by calculating the water hydrogen bond and reorientational dynamics. The hydrogen bond lifetime of interfacial water molecules is several times longer than that of bulk water due to the strong water-TiO2 interactions. A comparison of the dynamics simulated with the polarizable and non-surface polarity models shows that, while the hydrogen bond lifetime between the interfacial water and TiO2 surface is insensitive to the surface polarity, the reorientational dynamics around this hydrogen bond axis is significantly influenced by the surface polarity; the surface polarity of the TiO2 increases the water-TiO2 interactions, stabilizing the local structure of the interfacial water molecules and restricting their rotational motion. This reorientation occurs predominantly by rotation around the O-H group hydrogen bonded to the TiO2 surface. Furthermore, we correlate the dynamics of the induced charge on the TiO2 surface with the interfacial water dynamics. Our results show that the timescale of correlations of the atom charges induced by the local electric field in bulk water is influenced by the rotational motion, hydrogen bond rearrangement and translational motion, while the induced charge dynamics of the TiO2 surface is governed primarily by the rotational dynamics of the interfacial water molecules. This study demonstrates that the solid surface polarity has a significant impact on the dynamics of water molecules near TiO2 surfaces.

Real-time Observation of Interface Atomic Structures by an Energy-Dispersive Surface X-ray Diffraction

“…The atomic positions and Ti−O and O−O bond lengths indicate that; on the hydrophobic surface, the five-coordinated Ti atom was terminated with an O atom [denoted as OT in Figure 5(a)] which is likely in a form of water, the bridging O atom (OB) were not hydroxylated, and the surface was partially covered with adsorbed water molecules (AW) located at a lattice site (the site occupancy was ~0.3). These features are consistent with the previous CTR study on the surface immersed in water [45] and first-principles calculations [42,46]. On the superhydrophilic surface, large positional fluctuations were found for OT, OB, and the topmost TiO layer, and the ordered AW layer was lifted.…”

Influence of Surface‐Related Phenomena on Mechanism, Selectivity, and Conversion of TiO2‐Induced Photocatalytic Reactions

“…[21,22] Similarr esults have been experimentally obtained by scan diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS). This mechanism is in accord with other relevant reports.…”

“…This mechanism is in accord with other relevant reports. [21,22] Similarr esults have been experimentally obtained by scan diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS). It has been found that hydrogen bondingw ith adsorbed water ontoa natase TiO 2 (1 01)s tabilizes surfacetrapped holes, lowers the barrier for hole migration (which enhances carrier mobility), and suppresses chargesrecombination on the timescale of minutes.…”

Theoretical vibrational sum-frequency generation spectroscopy of water near lipid and surfactant monolayer interfaces. II. Two-dimensional spectra

“…This will help us to examine the quality of the spectroscopic models used in our simulations, as well as the lipid and water force fields. As we utilize simple, non-polarizable force fields in this study, we anticipate that better agreement between theory and experiment might be possible with more advanced force fields that take into account explicit polarization effects 74,75 or three-body forces. 76 Agreement between future experiments and our simulations will hopefully allow a detailed insight into and interpretation of interfacial water dynamics at lipid monolayer interfaces.…”