Poisoning of the Surface of Platinum Metals by Intermetallic Compound Formation

Abstract

SEVERAL, years ago¹ it was reported that the platinum metals differed in their relative effectiveness in catalysing the corrosion of less noble metals in boiling acids. The purpose of this communication is to point out that the lowered relative effectiveness of particular platinum metals in the presence of ions of a specific, less noble metal may be explained by the formation of an intermetallic compound on the surface of the platinum metal when it is polarized to a potential close to the corrosion potential of the less noble metal. Quantitative experiments on the system, platinum metal–tin–boiling 2 M hydrochloric acid, are cited to support this point of view.