XPS AND UPS OF PT CATALYSTS OF DIFFERENT PREPARATION

The techniques of XPS and UPS measurements with Pt black catalysts as well as reasonable data processing are discussed. The surface of Pt contains carbon and oxygen impurities in amounts of 15%-20% each. The use of various sensitivity factors does not influence the conclusions drawn on purity. Oxygen 1s and C Is line fitting has been done on a self-consistent basis. Of various chemical O and C species, three-dimensional carbon islands and water and/or H2O attached to Pt sites predominate. These latter entities are well detected also by UPS. The usefulness of difference XP and UP spectra in distinguishing chemical entities is pointed out.