Visible light induced photocatalytic activity of TiO2 nanowires photosensitized with CdSe quantum dots

In this study, the photocatalytic efficiency of CdSe quantum dot photosensitized TiO2 nanowires (~50 nm diameter) was examined under visible light irradiation. The sensitizer CdSe nanocrystals featured 3.1, 4.0, 4.6 and 6.0 nm mean diameter and a wurtzite crystal structure. The co-sensitization of the nanowires using the smallest and the largest nanocrystals was also investigated and these co-sensitized nanowires performed in almost the full visible-range spectrum. To attach the quantum dots onto the TiO2 surface, either a direct deposition method from toluene solution or an indirect linker molecule-assisted method with thioglycolic acid was applied. The photosensitized nanowires showed appreciable activity in a model photocatalytic test reaction. The best result was 71 % decrease of the initial methyl orange concentration with the co-sensitized nanowires after 6 h of visible light irradiation with a relatively low, 40 W output performance light source.