Colloidal TiO₂ nanocrystals with engineered defectivity and optical properties.

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Partially reduced titanium dioxide (TiO2), or "black" titania, is a promising visible-light photocatalyst.
• Existing synthesis methods involve harsh conditions (high temperature/pressure) or reactive precursors, leading to poor control over material properties.

Purpose of the Study:

• To develop a novel, low-temperature, atmospheric-pressure synthesis for TiO2 nanocrystals.
• To achieve independent control over oxygen vacancy density in TiO2 nanocrystals.

Main Methods:

• One-step synthesis of TiO2 colloidal nanocrystals.
• Controlled reaction temperature (as low as 280 °C) at atmospheric pressure.

Main Results:

• Achieved independent control of oxygen vacancy density over two orders of magnitude.
• Synthesized nanocrystals with homogeneous distribution of vacancies, not concentrated in an amorphous shell.
• Resulting defects are protected from oxidation, ensuring stable optical properties.

Conclusions:

• This method provides a pathway for stable, tunable black titania photocatalysts.
• The controlled synthesis enhances the potential of TiO2 for visible-light applications.
• Homogeneously distributed and protected oxygen vacancies are key to stable photocatalytic activity.