Ruthenium Oxide Anodes for Solid Polymer Electrolyte Water Electrolyzers: Electrochemical and Ellipsometric Studies

摘要

Ruthenium oxide (RuO/sub x/ is of considerable interest for the development of solid polymer electrolyte (SPE) water electrolyzers because of its high catalytic activity for the oxygen evolution reaction. As a first approach toward the understanding of the kinetics of this reaction, ellipsometric investigation of oxide films on Ru anodes was carried out in a 25% trifluoromethane sulfonic acid. The formation of Ru(OH) sub 3 film commences at approx. 0.73 V. At potentials above 0.94 V, Ru(OH) sub 3 is further oxidized to RuO sub 2 YH sub 2 O film. In situ optical analysis of Ru electrodes confirms that oxide films formed anodically can be removed by electroreduction. The critical potential at which Ru corrodes rapidly to H sub 2 RuO sub 5 is approx. 1.45 V. A dissolution-precipitation mechanism is proposed to explain the observed performance degradation with time during oxygen evolution on RuO/sub x/ anodes.