(116d) Modeling Pt/Sn/SnO2 Catalysts

Pt-Sn alloys have been used in a variety of catalytic reactions, including organic molecule oxidation (such as in fuel cells) or in hydrocarbon hydrogenation/dehydrogenation. Under reaction conditions however a synthesized alloy may change drastically. For instance segregation of Sn may occur or oxidation of Sn is possible leading to formation of SnO_x. We have used density functional theory to model possible Pt-Sn catalyst surfaces, namely pure Pt , pure Sn, a Pt-Sn alloy, and the interface between Pt-SnO₂. This latter interface was formed by modeling Pt nanorods over SnO₂(110), similar to previous work that modeled Au nanorods over TiO₂[1]. We present results on the oxygen reduction reaction and ethanol oxidation and highlight the differences between the various possible reaction systems under study. Our goal was to identify potential reaction sites on the various surfaces as well as reaction pathways. The nature of the Pt-SnO₂ interface in particular is explained, including the degree of charge transfer, role of surface defects, and the reactivity of interfacial sites between the two materials.

[1] L M Molina, M D Rasmussen, and B Hammer. The Journal of Chemical Physics 120, no. 16, 2004, p. 7673–80.