TiO2-based photocatalytic and antimicrobial coatings: comparison between sol-gel and electrodeposited silver/TiO2 nano-composites

M.V. Diamanti, L. Magagnin, B. Del Curto, G. Candiani, MP. Pedeferri
Politecnico di Milano, IT

Keywords: pollution, photocatalysis, doping, thin films, silver


Among possible ways to improve air quality in urban atmospheres, the use of nanostructured TiO2 films as photocatalysts is an excellent way to mitigate the problem, although it cannot offer a complete solution. TiO2 also induces significant photocatalytic degradation of liquid phase contaminants and for disinfection of wastewaters. Yet, it is important to find a suitable immobilization technique for TiO2 on different substrates. This work proposes a comparison between two immobilization systems: nanostructured TiO2 coatings on glass and polymers via sol-gel and silver doped acid sol-gel, and electrodeposited Ag/TiO2 nanocomposites on metallic substrates. Silver is beneficial to increase the film bioactivity in disinfection processes, as silver itself has a broad-spectrum bactericidal activity. Yet, it is important to verify that the presence of silver in a TiO2 layer is not detrimental to TiO2 photocatalytic activity. Gas pollutants (NO) and dyes (rhodamine B) were first considered as model reactants. The antibacterial effect of TiO2 was also studied on the most promising films, through the evaluation of total bacterial counts in the presence of TiO2 and Ag-doped TiO2 films on PMMA pellets. The doped films demonstrated an improved bacteria abatement; improvements are still needed to improve effectiveness.