Comparison of the effects generated by the dry-soft grinding and the photodeposition of Au and Pt processes on the visible light absorption and photoactivity of TiO₂

The influence of dry-soft grinding and photodeposition of gold (Au) or platinum (Pt) in the improvement of the photoactivity of TiO₂ synthesized by an integrated sol-gel and solvothermal method was studied. TiO₂ was modified by a dry-soft grinding process in a planetary ball mill (TiO₂(G)). Subsequently, Au or Pt particles were photodeposited in both unmodified TiO₂ and TiO₂(G) obtaining Au-TiO₂, Pt-TiO₂, Au-TiO₂(G), and Pt-TiO₂(G) materials. The photoactivity of the materials was evaluated in the phenol photodegradation under simulated solar radiation. Pt-TiO₂ showed the greatest degree of photoactivity improvement in comparison with TiO₂ and TiO₂-P25. The dry-soft grinding process led to a high photocatalytic activity of TiO₂(G) that was similar to Pt-TiO₂ activity as consequence of a slight increase in the crystallinity in TiO₂(G) due to an additional anatase formation in comparison with TiO₂. However, further photocatalytic improvement in TiO₂(G) were not achieved with the addition of Au or Pt. Therefore, the dry-soft grinding treatment and noble metal deposition led to similar improvements in the photocatalytic activity of TiO₂ for phenol oxidation.