| Abstract
| - The oxygen reduction reaction (ORR) was studied on CO-treated and untreated (111)−(100) nanofacetedplatinum surfaces [Komanicky et al. J. Phys. Chem.2005, 109, 23543] in sulfuric and perchloric acids usingthe rotating disk electrode technique. Activities of nanofaceted surfaces are found to be considerably higherthan a simple average of the activities of (111) and (100) surfaces. We find that the high activity in sulfuricacid is consistent with the higher activity of (111) facets. It is due the weaker sulfate adsorption on finite-size(111) surfaces than on (111) single crystal surfaces where the ORR activity is suppressed by strong sulfateadsorption. However, the high activity found in the weakly absorbing perchloric acid cannot be explained bythe finite-size effect, since the activities are reportedly insensitive to terrace sizes [Macia, M. D.; et al. J.Electroanal. Chem., 2004, 564, 141]. We propose a cooperative activity, unique to nanoscale objects, whichresults from oxy species crossing over between adjacent facets in nanometer proximities.
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