Strongly enhancing photocatalytic activity of tio₂ thin films by multi-heterojunction technique

The photocatalysts of immobilized TiO₂ film suffer from high carrier recombination loss when compared to its powder form. Although the TiO₂ with rutile-anatase mixed phases has higher carrier separation efficiency than those with pure anatase or rutile phase, the single junction of anatase/rutile cannot avoid the recombination of separated carriers at the interface. In this study, we propose a TiO₂/SnO₂/Ni multi-heterojunction structure which incorporates both Schottky contact and staggered band alignment to reduce the carrier recombination loss. The low carrier recombination rate of TiO₂ film in TiO₂/SnO₂/Ni multi-heterojunction structure was verified by its low photoluminescence intensity. The faster degradation of methylene blue for TiO₂/SnO₂/Ni multi-junctions than for the other fabricated structures, which means that the TiO₂ films grown on the SnO₂/Ni/Ti coated glass have a much higher photocatalytic activity than those grown on the blank glass, SnO₂-coated and Ni/Ti-coated glasses, demonstrated its higher performance of photogenerated carrier separation.