Z. Sun

Highly dispersed was prepared by freeze-drying followed by hydrogen reduction. The catalyst particle size was examined by transmission electron microscopy and X-ray diffraction line broadening technique as well as electrochemical Pt surface area measurement by and CO stripping. Oxygen reduction on Teflon bonded electrode was investigated under and air in 0.5 M at 25 and 70°C. was more active for oxygen reduction in sulfuric acid than Pt/C catalyst. The dissolved tungsten compounds (peroxy-tungstate) from the in the electrode participate in the oxygen reduction as a homogeneous catalyst for the decomposition of leading to significantly higher activity of the for oxygen reduction. By coating the electrode with a thin layer Nafion dispersion, continual loss of by dissolution and diffusion to the bulk electrolyte is avoided. © 2001 The Electrochemical Society. All rights reserved.

The activity of supported on Vulcan XC-72R carbon catalyst for oxygen reduction in the absence and presence of dissolved in was measured. The catalyst in sulfuric acid with dissolved in the electrolyte was far more active for oxygen reduction than those without dissolved . The activity of for oxygen reduction in in the presence of dissolved is doubled at , at vs. a standard hydrogen electrode. The mechanism of enhancement is due to the reaction of dissolved and to form hydroperoxy complexes, followed by the heterogeneous decomposition on to release . ©2000 The Electrochemical Society