Transparent Thin-Film TiO2 Photocatalysts with High Activity

A transparent, thin-film TiO2 layer prepared by sol−gel deposition is shown to be more active for photocatalytic oxidation (PCO) of acetaldehyde, acetic acid, and toluene than Degussa P25 thin films. The sol−gel TiO2 adsorbs 30−70% less organic, but the PCO activity per adsorbed molecule is 3.5−8.5 times higher on the sol−gel TiO2 than on Degussa P25. In addition, less-reactive intermediates do not appear to form as readily on the sol−gel catalyst as they do on Degussa P25, and thus the sol−gel catalyst deactivates slower during toluene PCO. Rates were measured in transient experiments for a monolayer of adsorbed organic, and transient experiments are shown to be an effective way to measure rates, selectivities, surface coverages, and formation of less-reactive intermediates in the same set of experiments.