The effect of WO₃ on the photocatalytic activity of TiO₂

Samples of WO₃/TiO₂ mixed oxide powders were prepared by two methods: (1) the incipient wetness impregnation of an aqueous ammonia solution of H₂WO₄ onto TiO₂ (P25), followed by heat treatment and (2) the ultrasonic nebulization and flame hydrolysis of a mixed isopropanol solution of tungsten(V) pentaethoxide and titanium(IV) tetraisopropoxide. The photocatalytic activities of TiO₂-based catalysts were evaluated by the degradation of 1,4-dichlorobenzene (DCB). The addition of WO₃ to TiO₂ greatly increased its photocatalytic behavior. This may be related to an increase in the transfer of electrons from the TiO₂ to the outer system, via the formation of an intermediate W(V) species.