Pt-Alloy and Dealloyed Catalysts

Reported activities differ widely. The measured activity is believed to depend largely on the catalyst surface/near-surface atomic composition and structure, on the presence or absence of surface impurities, and on particle size/shape [32, 33], All of these could be affected by preparation method, thermal treatment, and testing history. Alloys with mass activities of about two to three times that of Pt/C have been widely reported [3]. 

ELECTROCATALYST DESIGN IN PROTON EXCHANGE MEMBRANE FUEL CELLS 

FIGURE 13.3 High-angle annular dark-field (z-contrast) scanning transmission electron micrographs of partially dealloyed PtCUj precursor, showing (a) a Pt shell on a Cu-rich core and (b) large Swiss-Pt particles surrounded by smaller core-shell particles. Reprinted with permission from Ref. [29]. American Chemical Society. 

While it was shown in some systems that the target activity could be achieved with these catalysts, durability of the catalysts remains a concern. The current research focuses are (i) determining how thick the Pt-rich layer needs to be to provide both sufficient protection (thicker is better) and enhanced activity (thinner is better) and (ii) devising other methods to stabilize the base metal in the cores. 

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