Title: Synthesis and Characterization of Pt–Ag Alloy Nanocages with Enhanced Activity and Durability toward Oxygen Reduction

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. Here, 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^–1_Pt, which was still about two times that of the pristine Pt/C catalyst (0.19 A mg^–1_Pt).

Authors:

Yang, Xuan ^[1]; Roling, Luke T. ^[2]; Vara, Madeline ^[3]; Elnabawy, Ahmed O. ^[2]; Zhao, Ming ^[3]; Hood, Zachary D. ^[4]; Bao, Shixiong ^[1]; Mavrikakis, Manos ^[2]; Xia, Younan ^[1]

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+ Show Author Affiliations

1. Georgia Institute of Technology and Emory Univ., Atlanta, GA (United States)
2. Univ. of Wisconsin-Madison, Madison, WI (United States)
3. Georgia Inst. of Technology, Atlanta, GA (United States)
4. Georgia Inst. of Technology, Atlanta, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Fri Sep 23 00:00:00 EDT 2016

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

Contributing Org.:

Environmental Molecular Sciences Laboratory; the Center for Nanoscale Materials at Argonne National Laboratory; the National Energy Research Scientific Computing Center (NERSC); and the UW-Madison Center for High Throughput Computing (CHTC)

OSTI Identifier:

1398266

Grant/Contract Number:  

FG02-05ER15731

Resource Type:

Accepted Manuscript

Journal Name:

Nano Letters

Additional Journal Information:

Journal Volume: 16; Journal Issue: 10; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; density functional theory; nanocage; oxygen reduction reaction; platinum-based catalyst; Pt−Ag alloy