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IRG-I Highlight

Aberration corrected high-angle annular dark-field (HAADF) images of acid treated “Pt3Co” sample reveal the existence of percolated surfaces with Pt-rich and Co-rich regions (top left figure). In the annealed “Pt3Co” sample, Pt segregates in the top surface and Co is enriched in the next layer (top right figure, the atomic model of the highlighted particle is inserted). The segregated structures enable more significant modifications on the bond distance and the electronic structure of surface Pt atoms, which leads to greatly enhanced catalytic activity.

A step toward developing better fuel cells for electric cars and more

Reseachers in IRG-I have used a new technique called aberration-corrected Scanning Transmission Electron Microscopy to take the first images of individual atoms on and near the surface of platinum and cobalt nanoparticles, which are key catalysts in the creation of eco-friendly energy storage. The Shao-Horn group anticipates that knowing the surface composition of these nanoparticles will help them to design even better energy catalysts.

The team proposes that these combined platinum and cobalt nanoparticles are up to four times more active than platinum alone because the platinum atoms on the surface are constrained by the cobalt atoms underneath. The use of cobalt modifies the interatomic distances between the platinum atoms on the nanoparticle surface, making them more effective in the chemical reactions that are key to fuel cells. This work also bridges the gap between current understanding of electrocatalysis in bulk materials and at the nano-scale.

This research was performed in collaboration with Professor Paulo Ferreira of the University of Texas at Austin and Dr. Larry Allard of Oak Ridge National Laboratory, and was reported in the Sept. 24 online issue of the Journal of the American Chemical Society:

Shuo Chen, Paulo J. Ferreira,Wenchao Sheng, Naoaki Yabuuchi, Lawrence F. Allard, and Yang Shao-Horn, J. Am. Chem. Soc./ 2008, 130, 13818–13819.

This work was funded in part by the MRSEC Program of the National Science Foundation under Award No. DMR 02-13282.

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