Preparation and photocatalytic activity of Keggin-ion tungstate and TiO2 hybrid layer-by-layer film composites Original Research Article

Keggin ions (PW12O403− (PW12), SiW12O404− (SiW12), H2W12O406− (H2W12)) and TiO2 hybrid thin films were prepared using the layer-by-layer method. Their photocatalytic activities were investigated using gaseous 2-propanol decomposition. All films were transparent in the visible wavelength range. For 2-propanol decomposition, H2W12 was the most effective for the combination with TiO2 despite having the smallest TiO2 deposition amount. The photocatalytic activity of the PW12–TiO2 hybrid film was increased 2.3 times by visible light with UV illumination. This increase was less remarkable for hybrid films of other Keggin ions, suggesting that the visible light excitation of reduced PW12 plays an important role in the enhancement of 2-propanol decomposition.