Photocatalytic degradation of phenol using doped titania supported on photonic SiO2 spheres

Abstract

The photocatalytic degradation of phenol in aqueous suspensions of co-doped TiO2 supported on SiO2 spheres was investigated. A novel photocatalyst was prepared combining iron doped TiO2?SiO2 and reduced TiO2?SiO2 by mechanical milling (MM/TiO2?SiO2). All the particles were characterized by BET. nitrogen adsorption, X-ray diffraction, scanning electron microscopy, UV?visible spectroscopy and elemental analysis. Trough XRD patterns it was calculated that 2 nm rutile crystallites were formed onto SiO2 surface, ICP analysis confirmed Ti content near to nominal, while EDX analysis shows a surface content 10 lower, suggesting that the SiO2 limiting the agglomeration of TiO2 particles allowing a good dispersion. Phenol photodegradation was induced by illuminating the coated spheres in aqueous solution with a visible light source. The synthesized TiO2?SiO2 particles appeared to be 1.3 times more efficient in the phenol conversion, as compared to pure rutile particles. According to characterization results, this improvement could be attributed mainly to three factors: an effective transference of charge carriers trough the grain boundaries present between contact points, a photonic behavior evidenced on an increment on UV?vis absorption intensity and the quantum size effect of rutile crystallites coated on SiO2.