VOLTAMMETRIC BEHAVIOR OF IRREVERSIBLY ADSORBED SO2 ON A PT(111) ELECTRODE IN SULFURIC-ACID MEDIUM

Sulphur dioxide is irreversibly adsorbed on a Pt(111) surface in sulph uric acid medium giving species that are very stable towards electroch emical oxidation. The electrochemical reduction of irreversibly adsorb ed SO2 produces other strongly adsorbed species, one of which could be tentatively identified as atomic sulphur. SO2 adsorption followed by electrochemical removal of the resulting adspecies produces a structur al modification of the Pt(111) surface. This structural modification i s characterized by an increase in the number of (110) and (100) sites, by a diminution of the electric charge corresponding to the unusual a dsorption states and by a shift of these states to more positive poten tials.