AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThA

Paper SS1-ThA9
Synchrotron X-Ray Photoelectron Spectroscopy Studies of the Thermal Chemistry of (trimethyl) Methylcyclopentadienyl Platinum on Tio@sub 2@ (110)

Thursday, November 18, 2004, 4:40 pm, Room 210B

Session: Metal Oxides and Clusters IV: Oxide Surface Chemistry
Presenter: K. Adib, Brookhaven National Laboratory
Authors: K. Adib, Brookhaven National Laboratory
M.A. Barteau, University of Delaware
J. Hrbek, Brookhaven National Laboratory
J.M. White, University of Texas at Austin
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Pt/TiO@sub 2@ is one of the most important systems used in the photocatalytic decomposition of water to hydrogen as well as environmental purification of organic waste. In this regard, the use of organometallic precursors as sources of Pt metal islands on TiO@sub 2@ surfaces offers an attractive alternative to metal-vapor deposition techniques. We have used synchrotron X-ray photoelectron spectroscopy (XPS) to investigate the thermal chemistry of (trimethyl) methylcyclopentadienyl platinum (MeCpPtMe@sub 3@) on the stoichiometric rutile (110) surfaces. Our results indicate that the submonolayer adsorption of MeCpPtMe@sub 3@ on nominally stoichiometric TiO@sub 2@ (110) at 300 K does not result in substantial decomposition of the adsorbate. While subsequent annealing of the surface to 450 K enhances the decomposition of the MeCpPtMe@sub 3@, as evidenced by the appearance of additional Pt 4f peaks, there is no evidence of the desorption of the resulting carbon fragments even after extended periods of annealing. Predosing of nominally stoichiometric TiO@sub 2@ (110) surfaces with molecular oxygen at 300 K substantially enhances the decomposition of subsequently deposited MeCpPtMe@sub 3@. This decomposition is accompanied by the formation surface-bound CO@sub x@ species, possibly carboxylate groups, suggesting strong interactions between the adsorbate and substrate. Heating to 850 K can result in the removal of more than 98% of the surface bound carbon species, including the CO@sub x@, but does not result in the formation of a carbon-free Pt/TiO@sub 2@ surface.