The photocatalytic properties of anatase TiO2nanorods(NRs) and noble metal
semiconductor nanocomposites (TiO2NRs/Ag)prepared by colloidal chemistry routes and immobilized onto suitablesubstrates were investigated. Photocatalytic experiments were performedunder UV irradiation in order to test the degradation of a target compound(the azo dye, methyl red) in aqueous solution using TiO2P25 Degussa as areference material. Absorbance spectroscopy and liquid chromatography/mass spectrometry (LC/MS) measurements pointed out that, according topH conditions, TiO2NRs and TiO2NRs/Ag presented a photoactivity up to1.3 and 2 times higher than TiO2P25 Degussa, respectively. Notably, theTiO2NRs/Ag-based catalysts demonstrated a photocatalytic activity 2-foldhigher than bare TiO2NRs. Remarkably, only a negligible dependence on pH conditions was detected for the nanocompositecatalyst, whereas both TiO2NRs and TiO2P25 Degussa showed much higher photoactivity at acidic pH. In all the investigated cases,the identified byproducts pointed out the occurrence of the same reaction mechanism, basically relying on the hydroxyl radicalattaching on the benzene ring and on the homolytic rupture of the nitrogen
carbon bond of the dimethyl-amino moiety.