SULFUR-DIOXIDE ELECTROREDUCTION IN NONAQUEOUS MEDIA

A rotating disk electrode was used to study the influence of cathode m aterial and proton source on sulfur dioxide electroreduction in aproti c media. The one-electron reduction of sulfur dioxide to radical-anion s is quasi-reversible at pyrolytic carbon (PC) but irreversible at gol d. In the absence of protons, SO2 electroreduction can be written as: SO2 + e- --> SO2-. In the presence of protons and SO2, the polarizatio n curves recorded at gold exhibit two waves, those recorded at PC exhi bit an indistinct prewave owing to the promoter action of protons on s ulfur dioxide electroreduction and to the electrocatalytic properties of the cathode material toward the reduction of SO2 and HSO2(ads) in t he nonaqueous medium.