OXYGEN REDUCTION ON A MODIFIED RUTHENIUM ELECTRODE

Oxygen reduction has been studied in alkaline solution on a ruthenium electrode modified by thallium and lead adsorbates. A partially oxidized ruthenium electrode is inactive for oxygen reduction. Thallium and lead adsorbates cause pronounced changes on the ruthenium surface giving rise to a four electron-reduction of oxygen. Disc-ring electrode measurements show a predominant direct four electron-reduction, with a first charge-transfer rate determining step. Mass fractions of various reaction pathways have been calculated and the model explaining a direct four electron-reduction discussed. Once activated, ruthenium retains its activity even in the absence of thallium and lead ions in solution phase.