Photocatalytic Activity of Bulk TiO2 Anatase and Rutile Single Crystals Using Infrared Absorption Spectroscopy

A systematic study on the photocatalytic activity of well defined, macroscopic bulk single crystal TiO2 anatase and rutile samples has been carried out, which allows us to link photoreactions at surfaces of well defined oxide semiconductors to an important bulk property with regard to photochemistry, the life time of e h pairs generated in the bulk of the oxides by photon absorption. The anatase 101 surface shows a substantially higher activity, by an order of magnitude, for CO photo oxidation to CO2 than the rutile 110 surface. This surprisingly large difference in activity tracks the bulk e h pair lifetime difference for the two TiO2 modifications as determined by contactless transient photoconductance measurements on the corresponding bulk material