Peroxide and oxygen reduction on electrode surfaces

COLL 608

Xiao Li1, Karen Stewart2, and Andrew A. Gewirth, agewirth@uiuc.edu2. (1) Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, IL 61801, (2) Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801
Oxygen reduction is a theme that pervades many areas. Our interest is in the efficacious reduction of oxygen at electrode surfaces, a requirement for efficient fuel cells. In the first part of this talk, we report on our efforts directed at establishing the mechanism of oxygen and peroxide reduction on bare Pt and Cu, and on Au surfaces modified with ordered metal monolayers. By using a combination of spectroscopic, imaging, and x-ray scattering techniques combined with detailed calculations, we have shown that a crucial step involves the spontaneous clevage of the O-O bond to form a mixed metal-hydroxide complex. This hydroxide complex is reduced during the electron transfer event, leading to the product water. The conditions necessary to induce this clevage are now becoming understood. In the second part of the talk, we utilize the insight developed from the mechanistic studies to synthesize new oxygen reduction catalysts developed from nanostructured ensembles of metal ions and polymer. Studies directed at stabilizing the metal ions in the polymeric matrix in acid solution at high potentials and at increasing the activity of the catalyst will be highlighted.