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

• Hydrothermal synthesis yields photon responsive Bi-Ti-Ox composites.
• Reduced Bi can be identified on the surface of these composites.
• Photo-deposition of Pt leads to restructuring of the crystal morphology.
• Pt-Bi-Ti-Ox shows excellent performance in visible light photocatalysis.

Several remarkable observations regarding structure, (surface) composition and visible light induced photocatalytic activity of Bi-promoted Anatase photocatalysts are reported. First, XPS characterization data show that compositions of mixed Bi-Ti-oxide phases obtained by hydrothermal treatment at 180 °C of aqueous solutions 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 photo-deposition is accompanied by significant morphological changes. Third, the platinum functionalized, bismuth-promoted Anatase composites exhibit extraordinary photocatalytic activity in the photocatalytic degradation of organic compounds (acid orange 7 and salicylic acid, respectively) upon illumination at 447 nm, higher than observed for P25 upon UV illumination in similar reactor configuration. An optimized Pt-Bi-Ti-Ox composite consists of 1 wt% Pt and 5 wt% Bi. The high activity of the composite is discussed on the basis of the crystalline morphology and surface composition.

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