(1) Department of Electrochemistry, Moscow State University, Leninskie Gory 1-str.3, 119992 Moscow, Russia
Abstract:
The comparative study of isopolytungstates immobilized on smooth Pt and platinized Pt (Pt/Pt) provides a possibility to separate several specific effects on H- and O-upd at an external platinum surface and inside the pores of Pt/Pt. In the former case, a solid rechargeable product is formed (nonstoichiometric tungsten bronze), which an inherent porous structure allows solution penetration and does not prevent charging of the Pt/solution interface. Electrochemical responses of smooth Pt give more precise information on the film behaviour, when adsorption phenomena are clarified on the basis of data for Pt/Pt. Electrocatalytic tests (nitrate reduction) confirm unambiguously that the major part of the internal Pt/Pt surface area is modified by adsorbed polytungstate. This result gives, in its turn, new understanding of the size of Pt/Pt pores on the nanometre scale.