Title: Quantitative Analysis of the Reduction Kinetics Responsible for the One-Pot Synthesis of Pd–Pt Bimetallic Nanocrystals with Different Structures

Abstract

We report a quantitative understanding of the reduction kinetics responsible for the formation of Pd–Pt bimetallic nanocrystals with two distinctive structures. The syntheses involve the use of KBr to manipulate the reaction kinetics by influencing the redox potentials of metal precursor ions via ligand exchange. In the absence of KBr, the ratio between the initial reduction rates of PdCl₄^2– and PtCl₄^2– was about 10.0, leading to the formation of Pd@Pt octahedra with a core–shell structure. In the presence of 63 mM KBr, the products became Pd–Pt alloy nanocrystals. In this case, the ratio between the initial reduction rates of the two precursors dropped to 2.4 because of ligand exchange and, thus, the formation of PdBr₄^2– and PtBr₄^2–. The alloy nanocrystals took a cubic shape owing to the selective capping effect of Br^– ions toward the {100} facets. Relative to the alloy nanocubes, the Pd@Pt core–shell octahedra showed substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). Specifically, the specific (1.51 mA cm^–2) and mass (1.05 A mg^–1Pt) activities of the core–shell octahedra were enhanced by about four- and three-fold relative to the alloy nanocubes (0.39 mA cm^–2 and 0.34 A mg^–1Pt, respectively). Even after 20000more » cycles of accelerated durability test, the core–shell octahedra still exhibited a mass activity of 0.68 A mg^–1Pt, twice that of a pristine commercial Pt/C catalyst.« less

Authors:

Zhou, Ming ^[1]; Wang, Helan ^[2]; Vara, Madeline ^[3]; Hood, Zachary D. ^[4]; Luo, Ming ^[2]; Yang, Tung-Han ^[2]; Bao, Shixiong ^[2]; Chi, Miaofang  ^[5];

• Search DOE PAGES for author "Chi, Miaofang"
• Search DOE PAGES for ORCID "0000-0003-0764-1567"

Xiao, Peng ^[6]; Zhang, Yunhuai ^[6]; Xia, Younan ^[2]

---

+ Show Author Affiliations

1. Chongqing Univ. (China); Emory Univ., Atlanta, GA (United States); Georgia Institute of Technology, Atlanta, GA (United States)
2. Emory Univ., Atlanta, GA (United States); Georgia Institute of Technology, Atlanta, GA (United States)
3. Georgia Institute of Technology, Atlanta, GA (United States)
4. Emory Univ., Atlanta, GA (United States); Georgia Institute of Technology, Atlanta, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
6. Chongqing Univ. (China)

Publication Date:

Mon Sep 12 00:00:00 EDT 2016

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

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

OSTI Identifier:

1760157

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Volume: 138; Journal Issue: 37; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Palladium; Redox reactions; Platinum; Precursors; Nanocrystals