Generation of Active Sites for CO Photooxidation on TiO₂by Platinum Deposition

Photocatalytic oxidation of CO to CO2 was carried out with TiO2 and Pt/TiO2 catalysts at room temperature to investigate the effect of Pt deposition. The rate for CO photooxidation by Pt/TiO2 was higher than that by TiO2. The reaction rate increased with incident light intensity to the power of 0.7 for Pt/TiO2 and 0.5 for TiO2. The dependency of reaction rate on the concentration of CO and water vapor was explained in terms of Langmuir-Hinshelwood mechanism, where CO was more efficiently adsorbed on Pt sites compared with TiO2. On the basis of diffuse reflectance FTIR spectroscopic studies and CO photodesorption measurements, Pt on TiO2 acted as the active sites on which CO was chemically adsorbed and oxidized to CO2 on photoirradiation in the presence of O-2.