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.