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Issue 25, 2008
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Voltammetric surface dealloying of Pt bimetallic nanoparticles: an experimental and DFT computational analysis

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Abstract

Voltammetric dealloying of bimetallic platinum–copper (Pt–Cu) alloys has been shown to be an effective strategy to modify the surface electrocatalytic reactivity of Pt bimetallic nanoparticles (S. Koh and P. Strasser, J. Am. Chem. Soc., 2007, 129, 12624). Using cyclic voltammetry and structural XRD studies, we systematically characterize the Pt–Cu precursor compounds as well as the early stages of the selective Cu surface dissolution (dealloying) process for Pt25Cu75, Pt50Cu50, and Pt75Cu25 alloy nanoparticles annealed at both low and high temperature. We also assess the impact of the synthesis conditions on the electrocatalytic reactivity for the oxygen reduction reaction (ORR). To gain atomistic insight into the observed voltammetric profiles, we compare our experimental results with periodic DFT calculations of trends in the thermodynamics of surface Cu dissolution potentials from highly stepped and kinked Pt(854) single crystal surfaces. The modeling suggests a dependence of the electrochemical Cu dissolution potentials on the detailed atomic environment (coordination number, nature of coordinating atoms) of the bimetallic Pt–Cu surfaces. The DFT-predicted shifts in electrochemical Cu dissolution potentials are shown to qualitatively account for the observed voltammetric profiles during Cu dealloying. Our study suggests that metal-specific energetics have to be taken into account to explain the detailed dealloying behavior of bimetallic surfaces.

Graphical abstract: Voltammetric surface dealloying of Pt bimetallic nanoparticles: an experimental and DFT computational analysis

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Article information


Submitted
04 Mar 2008
Accepted
15 May 2008
First published
27 May 2008

Phys. Chem. Chem. Phys., 2008,10, 3670-3683
Article type
Paper

Voltammetric surface dealloying of Pt bimetallic nanoparticles: an experimental and DFT computational analysis

P. Strasser, S. Koh and J. Greeley, Phys. Chem. Chem. Phys., 2008, 10, 3670
DOI: 10.1039/B803717E

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