Effects of bismuth addition and photodeposition of platinum on (surface) composition, morphology and visible light photocatalytic activity of sol-gel derived TiO2.

Several remarkable observations regarding structure, (surface) compn. and visible light induced photocatalytic activity of Bi-promoted anatase photocatalysts are reported. First, XPS characterization data show that compns. of mixed Bi-Ti-oxide phases obtained by hydrothermal treatment at 180° C of aq. solns. of ethanol, titanium n-butoxide, and bismuth nitrate, are surface enriched with a specific fraction of metallic-like bismuth. Second, the formation of highly dispersed nanoparticles of platinum on these composites by photodeposition is accompanied by significant morphol. changes. Third, the platinum functionalized, bismuth-promoted Anatase composites exhibit extraordinary photocatalytic activity in the photocatalytic degrdn. of org. compds. (Acid orange 7 and salicylic acid, resp.) upon illumination at 447 nm, higher than obsd. for P25 upon UV illumination in similar reactor configuration. An optimized Pt-Bi-Ti-O composite consists of 1 wt% Pt and 5 wt% Bi. The high activity of the composite is discussed on the basis of the cryst. morphol. and surface compn. [on SciFinder(R)]