Photocatalytic activity of titania particles calcined at high temperature: Investigating deactivation

We examined the effect of high temperature calcination on the photocatalytic activity and photoexcited electron behavior of rutile TiO2 with a small specific surface area. Photocatalytic activity for H2 evolution was significantly decreased by calcination at temperatures higher than 500 °C, although the specific surface area showed little change. This deactivation was attributed to fast charge carrier recombination. Samples deactivated by high temperature calcination were reduced by hydrogen at 500 or 700 °C, increasing both the density of long-lived charge carriers and photocatalytic activity. These results suggest that density of oxygen vacancies is an important factor for photocatalytic reactivity.