New insights into the atomic structure of amorphous TiO₂ using tight-binding molecular dynamics

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Crystalline titanium dioxide (TiO2) is widely used in photocatalysis.
• The atomic structure of amorphous TiO2 (a-TiO2) is poorly understood compared to crystalline phases.
• Understanding a-TiO2 structure is crucial for optimizing its photocatalytic applications.

Purpose of the Study:

• To investigate the atomic structure and degree of order/disorder in amorphous TiO2.
• To compare the structural properties of a-TiO2 with its crystalline counterparts.
• To explore the relationship between a-TiO2 structure and its synthesis methods.

Main Methods:

• Classical molecular dynamics simulations were employed.
• A selection of empirical potentials was utilized.
• The second-moment tight-binding charge equilibration potential was specifically applied due to its dynamic charge assignment.

Main Results:

• The second-moment tight-binding charge equilibration potential demonstrated excellent agreement with experimental data.
• Simulations provided insights into the degree of order and disorder within a-TiO2.
• A significant flexibility in the local topology of a-TiO2 was identified.

Conclusions:

• Amorphous TiO2 exhibits a high degree of local topological flexibility.
• This flexibility likely accounts for the sensitivity of a-TiO2 structure to synthesis conditions.
• The findings enhance the understanding of amorphous TiO2 for potential photocatalytic advancements.