AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS2-ThM

Paper SS2-ThM9
The Chemistry of CeO@sub 2@(001) and Ce@sub 1-x@Zr@sub x@O@sub 2@(001) Studied by Mass-Spectroscopy of Recoiled Ions

Thursday, November 5, 1998, 11:00 am, Room 309

Session: Oxide Surface Chemistry
Presenter: G.S. Herman, Pacific Northwest National Laboratory
Authors: G.S. Herman, Pacific Northwest National Laboratory
Y. Gao, Pacific Northwest National Laboratory
C.H.F. Peden, Pacific Northwest National Laboratory
Correspondent: Click to Email
Ceria has found considerable use in automotive catalytic converters due to its oxygen storage properties. Ceria can provide oxygen under fuel-rich conditions, to reduce CO and hydrocarbon emissions, and remove oxygen under fuel-lean conditions, to reduce NOx emissions. The addition of zirconium to ceria has been found to improve the oxygen storage properties and increase the stability of the ceria particles. We have used the technique of mass-spectroscopy of recoiled ions (MSRI) to investigate the interaction of O@sub 2@, D@sub 2@, and D@sub 2@O with CeO@sub 2@(001) and Ce@sub 1-x@Zr@sub x@O@sub 2@(001) (x<0.20) films grown by plasma-assisted molecular beam epitaxy. The MSRI technique is extremely surface sensitive, probing the composition in the very topmost atomic layers. By using the temperature programmed mode of MSRI we were able to measure the corresponding signals for @super 18@O@sub 2@, D@sub 2@, and D@sub 2@O to monitor the adsorption, desorption and dissolution of these species. In the temperature range from 300-1000 K, we have found that the O signal increases linearly with temperature for all three molecules. The Ce signal, however, varies considerably over this temperature range depending on the molecular species. The results for the pure ceria and mixed ceria/zirconia films will be compared.