THE INFLUENCE OF PH ON REACTION PATHWAYS FOR O-2 REDUCTION ON THE AU(100) FACE

Oxygen reduction on the Au(100) face was studied by the rotating disk- ring electrode technique in solutions of anions which adsorb strongly on gold (HSO4-/SO42- and/or OH-) over the entire pH range. The specifi c adsorption of OH- anions, which is a pH dependent process, is found to play the key role in determining the reaction pathways. In the abse nce of OH- adsorption, for pHs below 6, the reduction of O-2 begins as a 2e-process. Due to the increase in local pH during O-2 reduction, t he reaction pathway turns into a 4e-reduction at a certain potential d epending on the pH of the solution. For pHs higher than 6, O-2 reducti on begins as a 4e-process in the potential region where specifically a dsorbed OH- anions are present. Copyright (C) 1996 Elsevier Science Lt d