The photocatalytic properties of Ti-Mo oxides prepared by a simple sol-gel route

Powders containing mixtures of titania and molybdite in different ratios were prepared by sol-gel processing. The sols were dried and subsequently calcined at 300, 500 and 700 C. Depending on the ratio of Ti and Mo in the initial sol and the calcination temperature, Ti-doped MoO₃, TiO ₂/MoO₃ or Mo-doped TiO₂ have been formed. The as prepared samples were characterised by scanning electron microscopy with attached X-ray dispersive energy analysis, X-ray diffractometry, Raman spectroscopy, gas adsorption and optical characterisation by ultraviolet/visible spectroscopy. The latter was used for the analysis of the photocatalytic properties on the decolourisation of methylene blue solutions under visible light irradiation. The phase composition, the specific surface and the photocatalytic activity were influenced by the molybdenum content and the calcination temperature. The final molybdenum content in the samples additionally depends on the calcination temperature. The optimum photocatalytic properties were observed or Ti-doped MoO₃.