Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9595587 | Surface Science | 2005 | 15 Pages |
Abstract
The adsorption of CO and the reaction of CO with pre-adsorbed oxygen at room temperature has been studied on the (2Â ÃÂ 1)ORh(1Â 1Â 1) surface and on vanadium oxideRh(1Â 1Â 1) “inverse model catalyst” surfaces using scanning tunnelling microscopy (STM) and core-level photoemission with synchrotron radiation. Two types of structurally well-defined model catalyst V3O9Rh(1Â 1Â 1) surfaces have been prepared, which consist of large (mean size of â¼50Â nm, type I model catalyst) and small (mean size <15Â nm, type II model catalyst) two-dimensional oxide islands and bare Rh areas in between; the latter are covered by chemisorbed oxygen. Adsorption of CO on the oxygen pre-covered (2Â ÃÂ 1)ORh(1Â 1Â 1) surface leads to fast CO uptake in on-top sites and to the removal of half (0.25Â ML) of the initial oxygen coverage by an oxidation clean-off reaction and as a result to the formation of a coadsorbed (2Â ÃÂ 2)OÂ +Â CO phase. Further removal of the adsorbed O with CO is kinetically hindered at room temperature. A similar kinetic behaviour has been found also for the CO adsorption and oxidation reaction on the type I “inverse model catalyst” surface. In contrast, on the type II inverse catalyst surface, containing small V-oxide islands, the rate of removal of the chemisorbed oxygen is significantly enhanced. In addition, a reduction of the V-oxide islands at their perimeter by CO has been observed, which is suggested to be the reason for the promotion of the CO oxidation reaction near the metal-oxide phase boundary.
Keywords
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
J. Schoiswohl, S. Eck, M.G. Ramsey, J.N. Andersen, S. Surnev, F.P. Netzer,