• 
  Xu, M.; Gao, Y.: Martinez Moreno, E.; Kunst, M.: Muhler, M.; Wang, Y.; Idriss, H.; Wöll, C.: Photocatalytic Activity of Bulk TiO₂ Anatase and Rutile Single Crystals Using Infrared Absorption Spectroscopy. Physical Review Letters 106 (2011), p. 138302/1-4

10.1103/PhysRevLett.106.138302

Abstract:
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 materials.