Acetone-Assisted Oxygen Vacancy Diffusion on TiO2(110).

Area of Science:

• Surface science
• Materials science
• Physical chemistry

Background:

• Titanium dioxide (TiO2) is a crucial material in catalysis and electronics.
• Oxygen vacancies (VO) significantly influence TiO2 surface properties and reactivity.
• Understanding defect dynamics is key to controlling material performance.

Purpose of the Study:

• To investigate the dynamic interaction between acetone and oxygen vacancies on the TiO2(110)-1 × 1 surface.
• To elucidate the mechanism of adsorbate-assisted oxygen vacancy diffusion.
• To correlate experimental observations with theoretical calculations.

Main Methods:

• Scanning tunneling microscopy (STM) at 300 K to visualize surface dynamics.
• Density functional theory (DFT) calculations to determine diffusion barriers and mechanisms.
• Isothermal STM imaging to track sequential diffusion events.

Main Results:

• Acetone preferentially adsorbs on oxygen vacancy sites and exhibits mobility.
• Two distinct diffusion channels for acetone were identified, both facilitating VO migration.
• Acetone diffusion along the oxygen row can heal VO, while diffusion to the titanium row leaves a VO behind.
• Calculated diffusion barriers align with experimental findings.

Conclusions:

• Acetone acts as a mobile agent that actively assists in the diffusion of oxygen vacancies on TiO2 surfaces.
• The study reveals a novel adsorbate-assisted defect diffusion mechanism.
• Findings provide insights into surface reactivity and defect engineering for TiO2-based applications.