Direct detection of OH radicals in the gas-phase diffused from the Pt/TiO2 and WO3/TiO2 photocatalysts under the UV-light irradiation

OH radicals diffused in the gas phase from the UV-irradiated Pt/TiO2 and WO3/TiO2 photocatalysts have been detected using the laser-induced fluorescence technique. Although the OH-LIF intensities for the Pt/TiO2 photocatalysts increased with increasing amount of Pt, those for the WO3/TiO2 photocatalysts decreased with increasing the amount of WO3. It was also found that the peak positions of the OH-LIF temporal profiles for the Pt/TiO2 and the WO3/TiO2 photocatalysts were slightly shifted compared with that for pure TiO2. Based on these experimental results a mechanism of OH-radical formation from the Pt/TiO2 and WO3/TiO2 photocatalysts was discussed.