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 TiO(2) 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 CO(2) than the rutile (110) surface. This surprisingly large difference in activity tracks the bulk e-h pair lifetime difference for the two TiO(2) modifications as determined by contactless transient photoconductance measurements on the corresponding bulk materials.