Direct evidence by in situ IR CO monitoring of the formation and the surface segregation of a Pt-Sn alloy.

The heat of CO adsorption on the Pt atoms of a Pt-Sn alloy phase could be specifically determined from in situ DRIFTS data and was found to be about half that measured on a plain Pt reference. Surprisingly, a reversible surface segregation of the Pt-Sn alloy was observed at temperatures below 175 °C.