Adsorption of carbon monoxide on platinum alloys: An infrared investigation

The effect of alloying on the absorption band frequency of CO adsorbed on Pt , v ( CO Pt ) , has been investigated with the alloys Pt-Pb, Pt-Sn, and Pt-Re. By use of the isotopic dilution method, it has been established that the downward shift of v ( CO Pt ) observed upon alloying Pt with Pb is caused partly by a dilution effect and partly by another, possibly electronic effect. Alloying Pt with Sn or Re, on the other hand, caused only a small shift of v ( CO Pt ) , which, moreover, could also be explained at least partly by a dilution effect. Oxidation of the alloy samples resulted in a phase separation of the components; the alloy situation could be restored again by a reduction procedure.