AVS 51st International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA10
Enhanced Photocatalytic Activity in Fe@sub 2@O@sub 3@/Cr@sub 2@O@sub 3@ Epitaxial Heterojunctions

Wednesday, November 17, 2004, 5:00 pm, Room 210B

Session: Metal Oxides and Clusters II: TiO@sub 2@ and Photocatalysis
Presenter: J.R. Williams, Pacific Northwest National Laboratory
Authors: J.R. Williams, Pacific Northwest National Laboratory
S.A. Chambers, Pacific Northwest National Laboratory
M.A. Henderson, Pacific Northwest National Laboratory
Correspondent: Click to Email
The heterogeneous photocatalytic activity may be enhanced by the creation of an oxide-oxide heterojunction where the band alignment is such that photoexcited electron-hole pairs tend to separate at the interface, resulting in enhanced charge carrier lifetimes. Here we show that epitaxial heterojunctions of Fe@sub 2@O@sub 3@ and Cr@sub 2@O@sub 3@ do indeed exhibit enhanced photocatalytic activity relative to either pure material. The dependence of the enhancement on the heterojunction thickness will be discussed, as well as the wavelength dependence. The heterojunctions were grown on @alpha@-Al@sub 2@O@sub 3@ substrates by Oxygen Plasma Assisted Molecular Beam Epitaxy (OPA-MBE). Characterization by XPS and all photocatalysis experiments are performed in situ after growth with no air exposure at any time. Photocatalytic activity is measured by the extent of decomposition of trimethylacetic acid (TMA) adsorbed on the surface using a quadrupole mass spectrometer, XPS, and a Hg arc lamp with various filters as the excitation source. Specifically we have observed a factor of ~ 2-3 increase in photocatalytic activity for this type of heterojunction surface as compared to the same surface of either pure material.