VO Cluster-Stabilized H₂O Adsorption on a TiO₂ (110) Surface at Room Temperature.

Area of Science:

• Surface Science and Catalysis
• Materials Chemistry
• Nanotechnology

Background:

• Titanium dioxide (TiO2) is a widely studied material with applications in catalysis and photocatalysis.
• Understanding water adsorption on TiO2 surfaces is crucial for many chemical processes.
• The role of surface defects, such as vanadium oxide (VO) clusters, in modifying TiO2 properties is of significant interest.

Purpose of the Study:

• To investigate the adsorption behavior of molecular water (H2O) on a TiO2 (110)-(1 × 1) surface modified with isolated VO clusters.
• To elucidate the structural and energetic aspects of H2O adsorption induced by VO clusters.
• To compare water adsorption on VO-decorated TiO2 with that on a clean TiO2 surface.

Main Methods:

• Ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) was employed to visualize water adsorption structures.
• Temperature-programmed desorption (TPD) was used to study water desorption kinetics and binding energies.
• Density functional theory (DFT) calculations were performed to understand the binding mechanisms and energetics.

Main Results:

• VO clusters on TiO2 (110)-(1 × 1) induce H2O adsorption at room temperature, forming distinct H2O dimer strings anchored by VO.
• TPD spectra revealed new water desorption states at 395 K and 445 K for VO-stabilized water, distinct from clean TiO2.
• DFT calculations confirmed enhanced H2O binding energy (0.42 eV higher) to VO clusters compared to the bare TiO2 surface.

Conclusions:

• Isolated VO clusters act as effective anchoring sites for molecular water adsorption on TiO2 (110) at room temperature.
• The unique H2O dimer string structures and enhanced binding are attributed to the H2O-VO-TiO2 interaction.
• This study highlights the potential of surface functionalization with VO clusters to control water adsorption on TiO2 for various applications.