IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS-TuA

Paper SS-TuA2
Photo-catalytic Reactions of Organic Molecules Over TiO@sub2@(001) Single Crystal - Effect of Surface Structure

Tuesday, October 30, 2001, 2:20 pm, Room 121

Session: Metal Oxides: Structure and Photocatalysis
Presenter: J. Wilson, The University of Auckland, New Zealand
Authors: H. Idriss, The University of Auckland, New Zealand
J. Wilson, The University of Auckland, New Zealand
Correspondent: Click to Email
No work has addressed so far the effect of surface reconstruction on the photochemical reactions of wide band-gap oxide semiconductors. Rutile, TiO@sub2@(001) single crystal a n-type semiconductor, band-gap 3.0 eV, is unique in that it possess two stable surface structures that can be obtained by thermal treatment. They are the (011)-faceted (750 K) and the (114)-faceted (> 950 K) surface. We have investigated the steady state reaction of acetic acid (as a prototype organic molecule) under photo-excitation (365 nm) over the two thermodynamically stable surfaces under ultra high vacuum conditions. Acetic acid was readily decomposed at room temperature into CO@sub2@ and CO. Moreover the formation of ethane, by the so-called "Photo-Kolbe" mechanism was clearly observed. On the (011)-faceted and at an acetic pressure of 2.4 x 10@super-7@ Torr the CO@sub2@, CO and, ethane production was 1.02 x 10@super-8@, 1.7 x 10@super-8@, and 4.51 x 10@super-9@ Torr, respectively. The product distribution on the (114)-faceted surface was found similar. However, it appears that this latter surface, the one containing Ti@super4+@ cations in 4, 5 and 6-fold coordination to oxygen anions is less active than the (011)faceted surface (all Ti@super4+@ cations are 5-fold coordinated to oxygen anions), under similar conditions.