Title: Understanding Composition-Dependent Synergy of PtPd Alloy Nanoparticles in Electrocatalytic Oxygen Reduction Reaction

Abstract

Gaining an insight into the relationship between the bimetallic composition and catalytic activity is essential for the design of nanoalloy catalysts for oxygen reduction reaction. This report describes findings of a study of the composition–activity relationship for PtPd nanoalloy catalysts in oxygen reduction reaction (ORR). Pt_nPd_100-n nanoalloys with different bimetallic compositions are synthesized by wet chemical method. While the size of the Pt₅₀Pd₅₀ nanoparticles is the largest among the nanoparticles with different compositions, the characterization of the nanoalloys using synchrotron high-energy X-ray diffraction (HE-XRD) coupled to atomic pair distribution function (PDF) analysis reveals that the nanoalloy with an atomic Pt:Pd ratio of 50:50 exhibits an intermediate lattice parameter. Electrochemical characterization of the nanoalloys shows a minimum ORR activity at Pt:Pd ratio close to 50:50, whereas a maximum activity is achieved at Pt:Pd ratio close to 10:90. The composition–activity correlation is assessed by theoretical modeling based on DFT calculation of nanoalloy clusters. In addition to showing an electron transfer from PtPd alloy to oxygen upon its adsorption on the nanoalloy, a relatively large energy difference between HOMO for nanoalloy and LUMO for oxygen is revealed for the nanoalloy with an atomic Pt:Pd ratio of 50:50. By analysis of the adsorption ofmore » OH species on PtPd (111) surfaces of different compositions, the strongest adsorption energy is observed for Pt₉₆Pd₁₀₅ (Pt:Pd ≈ 50:50) cluster, which is believed to be likely responsible for the reduced activity. Interestingly, the adsorption energy on Pt24Pd177 (Pt:Pd ≈ 10:90) cluster falls in between Pt₉₆Pd₁₀₅ and Pd₂₀₁ clusters, which is believed to be linked to the observation of the highest catalytic activity for the nanoalloy with an atomic Pt:Pd ratio of 10:90. Furthermore, these findings have implications for the design of composition-tunable nanoalloy catalysts for ORR.« less

Authors:

Wu, Jinfang ^[1]; Shan, Shiyao ^[2]; Cronk, Hannah ^[2]; Chang, Fangfang ^[2]; Kareem, Haval ^[2]; Zhao, Yinguang ^[2]; Luo, Jin ^[2]; Petkov, Valeri  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-6392-7589"

Zhong, Chuan-Jian  ^[2]

• Search DOE PAGES for author "Zhong, Chuan-Jian"
• Search DOE PAGES for ORCID "0000-0003-0746-250X"

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+ Show Author Affiliations

1. Inn Mongolia Univ., Hohhot (China); State Univ. of New York at Binghamton, NY (United States)
2. State Univ. of New York at Binghamton, NY (United States)
3. Central Michigan Univ., Mount Pleasant, MI (United States)

Publication Date:

Thu Jun 22 00:00:00 EDT 2017

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1437488

Grant/Contract Number:  

AC02-06CH11357; SC0006877; CHE 1566283

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 121; Journal Issue: 26; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

ENGLISH

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; palladium; metal nanoparticles; platinum; catalysts; cluster chemistry