AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA8
Adsorption and Reaction of NO on SrTiO@sub 3@ Surfaces

Monday, November 4, 2002, 4:20 pm, Room C-108

Session: Surface Reactions: CO and NO
Presenter: S. Azad, Pacific Northwest National Laboratory
Authors: S. Azad, Pacific Northwest National Laboratory
L.-Q. Wang, Pacific Northwest National Laboratory
M.H. Engelhard, Pacific Northwest National Laboratory
J. Szanyi, Pacific Northwest National Laboratory
C.H.F. Peden, Pacific Northwest National Laboratory
Correspondent: Click to Email
The adsorption and reaction of NO on metal oxide surfaces has recently received considerable attention in relation to the efficient removal of toxic pollutants from automobile exhaust. In this study, the reactivity of NO on SrTiO@sub 3@ surfaces has been investigated using temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). On oxidized surfaces containing predominantly Ti@super 4+@ cations NO was found to be much less reactive and desorbed mainly as molecular NO around 250 K. Similar TPD spectra obtained for NO adsorption on SrTiO@sub 3@ prepared by sputtering or annealing the surface to 750 K, 850 K and 900 K in vacuum and in O@sub 2@ suggested that thermal annealing of this surface did not affect the reactivity of NO with Ti@super 4+@ cation sites. However, a significant number of defects containing mainly Ti@super 3+@ (observed by XPS) that was created by Ar@super +@ ion bombardment greatly increased the reactivity of the surface towards the adsorbed NO molecules. NO is reduced by the Ti@super 3+@ sites on these defected surfaces and the major decomposition products are N@sub 2@ and N@sub 2@O. Co-adsorption of NO with CO on both reduced and oxidized surfaces has also been examined. The results of NO on SrTiO@sub 3@ surfaces will be compared with the results of ongoing studies of NO adsorption on Ce@sub 1-x@Zr@sub x@O@sub 2@/YSZ(111).