Influence of selected reactive oxygen species on the photocatalytic activity of TiO2/SiO2 composite coatings processed at low temperature

The influence of the crystalline phase and agglomeration degree of TiO2 nanoparticles embedded in an amorphous SiO2 matrix on the photocatalytic hydroxyl radical formation and bacterial inactivation was established in TiO2/SiO2 composite coatings, fabricated using a low-temperature, simple, and inexpensive technique. The photocatalytic hydroxyl radical formation was studied on TiO2/SiO2 coatings in presence of hole, electron, superoxide radical, and hydrogen peroxide scavengers, which can be present in bulk solution during wastewater disinfection. From the variation of rate constants for hydroxyl radical formation in the presence of each scavenger, we have established a relationship between hydroxyl radicals' formation and a charge carrier transfer mechanism between defect levels in SiO2 and TiO2 embedded nanoparticles by a simple spectroscopic method. This way, a final correlation between hydroxyl radical generation, crystalline phase, agglomeration degree, and bacteria inactivation has been obtained, thus complementing the lack of mechanisms behind the photocatalytic activity in TiO2/SiO2 composites.

Automated summary

The study established the influence of the crystalline phase and agglomeration degree of TiO2 nanoparticles on photocatalytic hydroxyl radical formation and bacterial inactivation in TiO2/SiO2 composite coatings. A relationship between hydroxyl radicals' formation and charge carrier transfer mechanism between defect levels in SiO2 and TiO2 embedded nanoparticles was established through a simple spectroscopic method. This correlation complements the lack of mechanisms behind the photocatalytic activity in TiO2/SiO2 composites.