TiO2–carbon nanotube composites for visible photocatalysts – Influence of TiO2 crystal structure

• TiO2–CNT composites with different TiO2 crystal structures were prepared.
• Improvement in photocatalytic activity under visible illumination for P25.
• Improvement in photocatalytic activity of anatase TiO2 under simulated solar illumination.
• Obtained results are strongly dependent on starting properties of TiO2.

We investigated the influence of the crystal structure of TiO2 and the use of different TiO2 precursors on the properties and photocatalytic activity of carbon nanotube (CNTs)–titania composites. We found that the crystal structure and properties of starting TiO2 nanomaterial significantly affected the effect of CNTs incorporation on the photocatalytic activity under simulated solar and visible light illumination (simulated solar illumination with UV-blocking filter). In case of significant photocatalytic activity under visible light illumination (anatase TiO2), likely due to the presence of native defects, composites exhibited lower activity under visible illumination only, but higher activity under simulated solar illumination. The opposite trends were observed for P25 (anatase + rutile) and rutile TiO2, where incorporation of CNTs resulted in a significant increase of photocatalytic activity under visible illumination. Thus, control over crystal structure and native defects is essential for the development of efficient visible light activated photocatalysts.