Synthesis and Characterization of Pt–Ag Alloy Nanocages with Enhanced Activity and Durability toward Oxygen Reduction
- 26 September 2016
- journal article
- research article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 16 (10), 6644-6649
- https://doi.org/10.1021/acs.nanolett.6b03395
Abstract
Engineering the elemental composition of metal nanocrystals offers an effective strategy for the development of catalysts or electrocatalysts with greatly enhanced activity. Herein, we report the synthesis of Pt-Ag alloy nanocages with an outer edge length of 18 nm and a wall thickness of about 3 nm. Such nanocages with a composition of Pt19Ag81 could be readily prepared in one step through the galvanic replacement reaction between Ag nanocubes and a Pt(II) precursor. After 10 000 cycles of potential cycling in the range of 0.60-1.0 V as in an accelerated durability test, the composition of the nanocages changed to Pt56Ag44, together with a specific activity of 1.23 mA cm-2 toward oxygen reduction, which was 3.3 times that of a state-of-the-art commercial Pt/C catalyst (0.37 mA cm-2) prior to durability testing. Density functional theory calculations attributed the increased activity to the stabilization of the transition state for breaking the O-O bond in molecular oxygen. Even after 30 000 cycles of potential cycling, the mass activity of the nanocages only dropped from 0.64 to 0.33 A mg-1Pt, which was still about two times that of the pristine Pt/C catalyst (0.19 A mg-1Pt).Keywords
Funding Information
- Division of Chemistry (CHE 1505441)
- Oak Ridge National Laboratory
- Georgia Institute of Technology
- Basic Energy Sciences (DE-FG02-05ER15731)
- Division of Graduate Education (DGE-1148903)
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