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Control of Architecture in Rhombic Dodecahedral Pt–Ni Nanoframe Electrocatalysts
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posted on 2017-08-08, 00:00 authored by Nigel Becknell, Yoonkook Son, Dohyung Kim, Dongguo Li, Yi Yu, Zhiqiang Niu, Teng Lei, Brian T. Sneed, Karren L. More, Nenad M. Markovic, Vojislav R. Stamenkovic, Peidong YangPlatinum-based
alloys are known to demonstrate advanced properties
in electrochemical reactions that are relevant for proton exchange
membrane fuel cells and electrolyzers. Further development of Pt alloy
electrocatalysts relies on the design of architectures with highly
active surfaces and optimized utilization of the expensive element,
Pt. Here, we show that the three-dimensional Pt anisotropy of Pt–Ni
rhombic dodecahedra can be tuned by controlling the ratio between
Pt and Ni precursors such that either a completely hollow nanoframe
or a new architecture, the excavated nanoframe, can be obtained. The
excavated nanoframe showed ∼10 times higher specific and ∼6
times higher mass activity for the oxygen reduction reaction than
Pt/C, and twice the mass activity of the hollow nanoframe. The high
activity is attributed to enhanced Ni content in the near-surface
region and the extended two-dimensional sheet structure within the
nanoframe that minimizes the number of buried Pt sites.