STABILITY OF PT SURFACES IN NONAQUEOUS MEDIA AND THEIR SURFACE EFFECTIN THE ANODIC-OXIDATION OF CHLORIDE-IONS IN NITROMETHANE SOLUTION

The stability of the surface of a polycrystalline electrofacetted Pt e lectrode was studied in nitromethane (NM). It was observed that if the electrode was transferred from aqueous solution into NM and back with out electrochemical polarization being applied in NM, the surface show ed the same hydrogen deposition/oxidation pattern as before. Following prolonged polarization in NM the hydrogen capacity decreased while th e ratio of weakly and strongly adsorbed hydrogen changed only to a min or extent. The results provided an opportunity to extend studies of el ectrocatalytic effects of oriented platinum surfaces in non-aqueous me dia and to correlate the electrocatalytic activity of single crystal a nd oriented Pt surfaces in the anodic oxidation of chloride ions in ni tromethane solution with the adsorption properties of the surfaces det ermined in aqueous solution. The kinetic parameters evaluated revealed that the results obtained can be interpreted as a recombination-contr olled process taking place preferentially on ''weakly'' bonding adsorp tion sites.