Real-time investigation on photocatalytic oxidation of gaseous methanol with nanocrystalline WO3-TiO2 composite films

Here we report on our investigation on photocatalytic oxidation (PCO) of gaseous methanol with WO₃-TiO₂ composite films. WO₃ and WO₃-TiO₂ composite thin films were prepared by drop casting method. PCO of gaseous methanol and hydrogen generation process on platinum loaded WO₃-TiO₂ composite thin films in high vacuum were investigated using a home-made reactor with a six-channel quadrupole mass spectrometer at real-time scale under UVA (300-400 nm) light illumination.In the case of Pt loaded WO₃ thin films, PCO of gaseous methanol proceeds through intermediates viz. formaldehyde, CO and finally to CO₂ and H₂. PCO of gaseous methanol occurs via direct hole transfer over Pt loaded WO₃ thin films. On the other hand, PCO of gaseous methanol over Pt loaded WO₃-TiO₂ composite thin films proceeds with competitive direct and indirect hole transfer reactions. Our real-time analysis of gas phase photocatalysis realized the identification of direct and indirect hole transfer processes and the reaction intermediates thereof.