Effect of structure on the photocatalytic activity of Pt-doped TiO2 nanotubes

Highly ordered TiO2 nanotubes with different tube length were fabricated by anodization using C2H2O4·2H2O containing 0.5 wt.% NH4F (electrolyte A) and anhydrous dimethyl sulfoxide containing 1% HF (electrolyte B), respectively. Then cathodic reduction method was used to dope Pt in TiO2 nanotubes in chloroplatinic acid. The results indicated that cathodic reduction could efficiently platinize TiO2 nanotubes. Pt-doped TiO2 nanotubes with the longer length had the higher photocatalytic activity for degrading methyl orange under UV and visible irradiation. The longer tube length has a positive effect on the photocatalytic activity of Pt-doped TiO2 nanotubes. Besides, as the content of anatase further decreases, the photocatalytic activity drops gradually due to the reduction reaction in the surface area.