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Title: Structural Evolution of Sub-10 nm Octahedral Platinum$-$Nickel Bimetallic Nanocrystals

Octahedral Pt alloy nanocrystals (NCs) have shown excellent activities as electrocatalysts toward oxygen reduction reaction (ORR). As the activity and stability of NCs are highly dependent on their structure and the elemental distribution, it is of great importance to understand the formation mechanism of octahedral NCs and to rationally synthesize shape-controlled alloy catalysts with optimized ORR activity and stability. However, the factors controlling the structural and compositional evolution during the synthesis have not been well understood yet. Here in this paper, we systematically investigated the structure and composition evolution pathways of Pt–Ni octahedra synthesized with the assistance of W(CO) 6 and revealed a unique core–shell structure consisting of a Pt core and a Pt–Ni alloy shell. Below 140 °C, sphere-like pure Pt NCs with the diameter of 3–4 nm first nucleated, followed by the isotropic growth of Pt–Ni alloy on the seeds at temperatures between 170 and 230 °C forming Pt@Pt–Ni core–shell octahedra with {111} facets. Owing to its unique structure, the Pt@Pt–Ni octahedra show an unparalleled stability during potential cycling, that is, no activity drop after 10 000 cycles between 0.6 and 1.0 V. This work proposes the Pt@Pt–Ni octahedra as a high profile electrocatalyst for ORR and revealsmore » the structural and composition evolution pathways of Pt-based bimetallic NCs.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [3] ;  [3] ; ORCiD logo [2] ; ORCiD logo [4]
  1. Hong Kong Univ. of Science and Technology, Hong Kong (China)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  3. Kyungpook National Univ., Daegu (Korea, Republic of). Dept. of Chemistry and Green-Nano Materials Research Center
  4. Hong Kong Univ. of Science and Technology, Hong Kong (China); Hong Kong Univ. of Science and Technology, Hong Kong (China). Energy Inst.
Publication Date:
Report Number(s):
BNL-113903-2017-JA
Journal ID: ISSN 1530-6984; KC0403020
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 6; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Research Foundation of Korea (NRF); Hong Kong University of Science and Technology
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Pt-Ni octahedra; structural evolution; core-shell; oxygen reduction reaction; durability; Center for Functional Nanomaterials
OSTI Identifier:
1362156