AVS 56th International Symposium & Exhibition
    In Situ Microscopy and Spectroscopy: Interfacial and Nanoscale Science Topical Conference Thursday Sessions
       Session IS+SS-ThM

Paper IS+SS-ThM1
Reduction of Cationic Sn in SnOx/PtSn Alloy Surfaces

Thursday, November 12, 2009, 8:00 am, Room C4

Session: In-Situ Spectroscopy - Interfacial Science & Catalysis
Presenter: B. Koel, Lehigh University
Authors: G. Liu, Lehigh University
H. Bluhm, Lawrence Berkeley National Laboratory
B. Koel, Lehigh University
Correspondent: Click to Email
Understanding mechanisms of catalyst selectivity requires improved knowledge of oxidation and reduction reactions that occur at the metal/metal oxide interface. We describe studies that probe the thermal stability and reducibility of cationic Sn at SnOx/PtSn alloy interfaces for several different and well-defined surface phases of SnOx that can be formed depending on the temperature. Our investigations covered a wide range of conditions, from vacuum to the chemical changes during exposures to H2 at pressures up to 5 Torr by using in-situ high pressure photoelectron spectroscopy (HPPES). We find enormous differences in the reducibility of cationic Sn species showing that local surface structure and composition plays an key role in governing these reactions. These studies help to define the overall chemical reactivity of SnOx species at these interfaces, and in particular, clarify the role of reduced and cationic Sn sites in selective hydrogenation of crotonaldehyde.