An investigation of the combustion of platinum

Abstract

The attack of metal surfaces by gases at low pressures under conditions suet that the products of reaction volatilise too rapidly to affect the reaction velocity is one of the simplest heterogeneous actions and presents many analogies to a simple catalytic action at a surface. Langmuir studied the rate of attack of tungsten by oxygen under these conditions and in this communication the interaction of platinum with oxygen is described. This element was chosen, not only on account of the importance of reactions involving the "clean up" of gases in contact with hot filaments, but also because the electron work functions of both tungsten and platinum are known, so that their relation ship to the reaction rate could be studied. That some connection may exist between the reactivity of a surface and the ease of electron emission has been suggested previously and is to be noted particularly in the investigations of Sir Humphry Davy on the oxidation on zinc and copper, of Langmuir, and of Thompson, Bone, Thomas, and Brine on the surface combustion of gases. From a somewhat different standpoint others, notably Brewer, and Finch and Stimson, suggest that surface reactions take place only after formation of ions on the surface has occurred, the former postulating that ions are formed by molecules entering the intrinsic field of the metal surface and react only after emergence from the field.