AVS 53rd International Symposium
    Surface Science Friday Sessions
       Session SS-FrM

Paper SS-FrM1
Reduction of Sn-Oxide Phases on PtSn Alloys

Friday, November 17, 2006, 8:00 am, Room 2002

Session: Oxide Surfaces and Interfaces
Presenter: B.E. Koel, Lehigh University
Authors: J. Kim, Lehigh University
S. Thomas, University of Southern California
B.E. Koel, Lehigh University
Correspondent: Click to Email
The chemistry that occurs at oxide-metal interfaces found for metal nanoparticles on oxide supports or formed by oxidation of the metal nanoparticles themselves is important for understanding and controlling processes in heterogeneous catalysts, electrocatalysts, and sensors. For example, the origin of improved selectivity of Pt-Sn bimetallic catalysts for selective hydrogenation of unsaturated aldehydes has been attributed to the presence of cationic Sn sites. We have investigated the thermal stability, and reducibility in H@sub 2@ at pressures ranging from UHV to one atm., of several distinct ordered and disordered structures, monolayer and multilayer phases, of tin oxide films formed at the surface of Sn/Pt(111) and Sn/Pt(100) surface alloys. The oxide phases and the progress of their reduction were characterized using TPD, LEED, STM, AES, and high-resolution XPS. We find enormous sensitivity of the reduction of these tin oxide films on the detailed chemical nature and structure of the films. Such sensitivity can alter the thermal reduction temperature by 300 K and the reducibility in H@sub 2@ by many orders of magnitude.