Title: PdCu Nanoalloy Electrocatalysts in Oxygen Reduction Reaction: Role of Composition and Phase State in Catalytic Synergy

Abstract

The catalytic synergy of nanoalloy catalysts depends on the nanoscale size, composition, phase state, and surface properties. This report describes findings of an investigation of their roles in the enhancement of electrocatalytic activity of PdCu alloy nanoparticle catalysts for oxygen reduction reaction (ORR). In this work Pd_nCu_100–n nanoalloys with controlled composition and subtle differences in size and phase state were synthesized by two different wet chemical methods. Detailed electrochemical characterization was performed to determine the surface properties and the catalytic activities. The atomic-scale structures of these catalysts were also characterized by high-energy synchrotron X-ray diffraction coupled with atomic pair distribution function analysis. The electrocatalytic activity and stability were shown to depend on the size, composition, and phase structure. With Pd_nCu_100–n catalysts from both methods, a maximum ORR activity was revealed at Pd/Cu ratio close to 50:50. Structurally, Pd₅₀Cu₅₀ nanoalloys feature a mixed phase consisting of chemically ordered (body-centered cubic type) and disordered (face-centered cubic type) domains. The phase-segregated structure is shown to change to a single phase upon electrochemical potential cycling in ORR condition. While the surface Cu dissolution occurred in PdCu catalysts from the two different synthesis methods, the PdCu with a singlephase character is found to exhibit amore » tendency of a much greater dissolution than that with the phase segregation. Analysis of the results, along theoretical modeling based on density functional theory calculation, has provided new insights for the correlation between the electrocatalytic activity and the catalyst structures.« less

Authors:

Wu, Jinfang ^[1]; Shan, Shiyao ^[2]; Luo, Jin ^[2]; Joseph, Pharrah ^[2]; Petkov, Valeri ^[3]; Zhong, Chuan-Jian ^[2]

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+ Show Author Affiliations

1. State Univ. of New York (SUNY), Binghamton, NY (United States); Chongqing Univ. (China)
2. State Univ. of New York (SUNY), Binghamton, NY (United States)
3. Central Michigan Univ., Mount Pleasant, MI (United States)

Publication Date:

Mon Nov 16 00:00:00 EST 2015

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)

Sponsoring Org.:

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

OSTI Identifier:

1237750

Grant/Contract Number:  

SC0006877; AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Volume: 7; Journal Issue: 46; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

ENGLISH

Subject:

36 MATERIALS SCIENCE; Palladium; Catalysts; Redox reactions; Bimetals; Catalytic activity