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.

Highlights
- TiO2 nanotubes anodized in 1/12 M C2H2O4·2H2O containing 0.5 wt.% NH4F (electrolyte A) displayed an obvious tubular structure with the average length of 700 nm.
- TiO2 nanotubes anodized in anhydrous dimethyl sulfoxide containing 1% HF (electrolyte B) showed the inhomogeneous cracked surface with the average length of 3 μm.
- Pt-doped TiO2 anodized in electrolyte B (400 °C) showed the highest photocatalytic activity.