| AVS 56th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session I and Mort Traum Finalists |
| Presenter: | T.Q. Nguyen, Osaka University, Japan |
| Authors: | T.Q. Nguyen, Osaka University, Japan M.C.S. Escaño, Osaka University, Japan S. Kunikata, Osaka University, Japan H. Nakanishi, Osaka University, Japan H. Kasai, Osaka University, Japan H. Maekawa, Isuzu Advanced Engineering Center, Ltd., Japan K. Osumi, Isuzu Advanced Engineering Center, Ltd., Japan Y. Tashiro, Isuzu Advanced Engineering Center, Ltd., Japan |
| Correspondent: | Click to Email |
Air pollution from automobile exhaust is one of the major environmental problems in modern civilization. In order to reduce the amount of noxious pollutions, the diesel oxidation catalyst (DOC) systems are widely used. In the DOC system, CO and Hydrocarbon (HC) are oxidized to harmless chemical substances such as H2O, CO2, and NO is converted to NO2.1-4 DOCs have a honeycomb-like, monolithic structure. The monolith support is made either from metallic (stainless steel) or ceramic material and coated with a so-called “washcoat”. The washcoat consists of high porous oxides, such as γ-Al2O3 (alumina), and precious metals, such as Pt, Pd, and Rh plus more additives (e.g., CeO2 and ZrO2) to increase the catalytic activity or to stabilize the structure of the catalyst. In DOCs, Cerium is present in high quantities in the form of CeO2. Cerium renders multiple functions, the most vital of which is to store and to release oxygen under fuel-lean and fuel-rich conditions. This is so-called the oxygen storage capacity (OSC), which allows the catalyst to operate over wider air to fuel ratio.5
In this work, we investigate the adsorption of Pt atom on unreduced and reduced CeO2(111) surface by using first-principles method. With the aim of having a better understanding of the catalytic properties of Pt/CeO2 for further development and improvement of DOCs, we concentrated on the details of Pt adsorption on CeO2, the formation of oxygen vacancies at Pt/CeO2 surfaces and how it affects the geometric and electronic structures as well as chemical properties of surface. We found that, some metal induced gap states appeared under the adsorption of Pt, which is due to the strong interaction between Pt 5d and O 2p. This is the factor that makes the Pt/CeO2 system more active than the clean CeO2 surface. In addition, the adsorption of Pt accelerates the formation of surface vacancies and enhances the OSC. A more detailed discussion of these results will be conducted in the meeting.
References
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