Preparation and Characterization of Au/Pd Modified-TiO2 Photocatalysts for Phenol and Toluene Degradation under Visible Light-The Effect of Calcination Temperature

Rutile loaded with Au/Pd nanoparticles was prepared using a water-in-oil microemulsion system of water/AOT/cyclohexane followed by calcination. The effect of calcination temperature (from 350 to 700 degrees C) on the structure of Au/Pd nanoparticles deposited at rutile matrix and the photocatalytic properties of Au/Pd-TiO2 was investigated in two model reactions (toluene degradation in gas phase and phenol degradation in aqueous phase). Toluene was irradiated over Au/Pd-TiO2 using light emitting diodes(LEDs, lambda(max) = 415 nm). The sample 0.5 mol% Pd/TiO2 exhibited the highest activity under visible light irradiation in gas and aqueous phase reaction among all photocatalysts calcined at 350 degrees C, while the sample modified only with gold nanoparticles showed the lowest activity. The Au/Pd-TiO2 sample calcinated at 350 degrees C possesses the highest photocatalytic activity when degrading phenol under visible light, which is 14 times higher than that of the one calcinated at 450 degrees C. It was observed that increasing temperature from 350 to 700 degrees C during calcination step caused segregation of metals and finally resulted in photoactivity drop.