TiO2, TiO2/Ag and TiO2/Au photocatalysts prepared by spray pyrolysis

TiO2, TiO2/Ag and TiO2/Au photocatalysts exhibiting a hollow spherical morphology were prepared by spray pyrolysis of aqueous solutions of titanium citrate complex and titanium oxalate precursors in one-step. Effects of precursor concentration and spray pyrolysis temperature were investigated. By subsequent heat treatment, photocatalysts with phase compositions from 10 to 100% rutile and crystallite sizes from 12 to 120 nm were obtained. A correlation between precursor concentration and size of the hollow spherical agglomerates obtained during spray pyrolysis was established. The anatase to rutile transformation was enhanced with metal incorporations and increased precursor concentration. The photocatalytic activity was evaluated by oxidation of methylene blue under UV-irradiation. As-prepared TiO2 particles with large amounts of amorphous phase and organic residuals showed similar photocatalytic activity as the commercial Degussa P25. The metal incorporated samples showed comparable photocatalytic activity to the pure TiO2 photocatalysts.