A High Pressure PM-IRRAS Study of CO and O₂ Coadsorption and Reactivity on PtSn Alloy Surfaces

Abstract

The adsorption of CO on the two terminations, p(2 × 2) and (√3 × √3) R30°, of the bulk Pt3Sn(111) alloy is studied by high pressure polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). The influence of O2 is also investigated. While no differences are observed when CO is chemisorbed alone, the behavior of the two terminations clearly differs in presence of O2. The presence of oxygen induces modifications on the (√3 × √3)R30° surface. Finally we study how the interaction between O2 and the surface modifies the reactivity. Hence we show that the p(2 × 2) termination is more efficient than the (√3 × √3) R30° for CO oxidation. However this termination remains more efficient than pure platinum.