| AVS 57th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS-WeA |
| Session: | Chemisorption and Surface Reactions |
| Presenter: | J. Szanyi, Pacific Northwest National Laboratory |
| Authors: | K. Mudiyanselage, Pacific Northwest National Laboratory C.-W. Yi, Sungshin Women's University, Republic of Korea J. Szanyi, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
The formation of Oad species and their reactivities in CO oxidation on BaO/Pt(111) were studied with temperature programmed desorption (TPD), infrared reflection absorption (IRA) and X-ray photoelectron (XP) spectroscopies. Two BaO/Pt(111) model systems with different BaO coverages were prepared and studied. The Pt(111) surface in both of these systems was not completely covered with BaO. On the system with lower BaO coverage (~50 % of the Pt(111) surface was free of BaO), two different Oad species form following the adsorption of O2 at 300 K; O adsorbed on clean Pt(111) sites and at the Pt-BaO interface. On the system with higher BaO coverage (~70 % of the Pt(111) surface is covered by BaO) two types of Oad are seen at the Pt/BaO interface. The desorption of oxygen from the BaO-free portion of the Pt(111) surface gives an O2 desorption peak with a maximum desorption rate at ~ 690 K. Recombinative desorption of interfacial Oad gives two explosive-desorption features at ~ 760 and ~ 790 K in the TPD spectrum. The reactivities of these adsorbed O species with CO to from CO2 follow their order of desorption; i.e., the Oad associated with the clean Pt(111) surface and desorbs at 690 K reacts first with CO, followed by the Oad species at the BaO/Pt(111) interface (first the one that desorbs at ~ 760 K and finally the one that is bound the most strongly to the interface, and desorbs at ~ 790 K).