Electrochemisorption of Hexahydroxyplatinate(IV) On Tin Oxide Films: Electrochemical and UHV Spectroscopic Studies of the Product

Abstract

The electrochemical preparation of platinized tin oxide surfaces from solutions containing hexahydroxyplatinate(IV) ions is examined as a function of anodic platinization potential over the range from 0.0 to 1.0V vs. SCE. Both electrochemical and ultrahigh vacuum surface techniques including electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES) were used to characterize the resulting surfaces. Both ESCA and an electrochemical method show that the amount of Pt deposited is a strong function of the deposition potential and that a maximum occurs at 0.4V vs. SCE. Furthermore, the amount of platinum deposited correlates with the oxygen‐to‐tin ratio at the surface, the chemical state of the Pt, and the sample work function as determined by ESCA. The amount of Pt deposited is also large at highly anodic potentials when the deposition is carried out in the presence of , but ESCA shows that the Pt is oxidized to a greater extent. AES results support the conclusions drawn from the electrochemical and ESCA studies. From these data it is suggested that the nature and concentration of the active sites at the surface vary as a function of anodic potential thereby influencing the amount and form of the deposited Pt.