TiO2 thin film photocatalysts that can be operated under visible light irradiation were successfully designed and developed by applying an ion engineering technique, i.e., the RF magnetron sputtering deposition method. These TiO2 thin film photocatalysts prepared at the relatively higher deposition temperatures were able to absorb light in visible regions efficiently and were observed to decompose NO into N2, O2 and N2O under visible light (λ > 450 nm) irradiation at 275 K. On the other hand, the TiO2 thin films prepared at the relatively lower deposition temperature exhibited a high transparency and high photocatalytic reactivity for the decomposition of NO under UV light (λ > 270 nm) irradiation at 275 K.
