Size-specific catalytic activity of platinum clusters enhances oxygen reduction reactions

Abstract

Colloidal platinum nanoparticles with diameters of 2–5 nm on carbon supports are currently regarded as the best catalysts for the oxygen reduction reaction. However, the particle size is limited by the conventional preparation methods that are used to synthesize small platinum particles; the inherent activity of ultrasmall nanoparticles has not yet been revealed. We present a practical synthesis for ultrafine subnanometre platinum clusters using a spherical macromolecular template with no disorder in molecular weight or structure. The template, a phenylazomethine dendrimer, offers control of the number of metal complexes in an assembly through stepwise complexation, allowing the complexes to accumulate in discrete nano-cages. Subsequent reduction of Pt(IV) chloride to Pt(0) results in the formation of platinum clusters composed of a defined number of atoms. As a result of exceptionally small particle size, the clusters exhibit very high catalytic activity for the four-electron reduction of oxygen molecules. Platinum nanoparticles are excellent catalysts, but maintaining that effectiveness at ever smaller particle sizes is crucial to make best use of the precious metal. Now, a dendrimer has been used as a template to make subnanometre clusters, with a defined number of atoms, that exhibit high catalytic activity.

Cite this article

Yamamoto, K., Imaoka, T., Chun, WJ. et al. Size-specific catalytic activity of platinum clusters enhances oxygen reduction reactions. Nature Chem 1, 397–402 (2009). https://doi.org/10.1038/nchem.288

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