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Title: Size-dependent disorder-order transformation in the synthesis of monodisperse intermetallic PdCu nanocatalysts

The high performance of Pd-based intermetallic nanocatalysts has the potential to replace Pt-containing catalysts for fuel-cell reactions. Conventionally, intermetallic particles are obtained through the annealing of nanoparticles of a random alloy distribution. However, this method inevitably leads to sintering of the nanoparticles and generates polydisperse samples. Here, monodisperse PdCu nanoparticles with the ordered B2 phase were synthesized by seed-mediated co-reduction using PdCu nanoparticle seeds with a random alloy distribution (A1 phase). A time-evolution study suggests that the particles must overcome a size-dependent activation barrier for the ordering process to occur. Characterization of the as-prepared PdCu B2 nanoparticles by electron microscopy techniques revealed surface segregation of Pd as a thin shell over the PdCu core. The ordered nanoparticles exhibit superior activity and durability for the oxygen reduction reaction in comparison with PdCu A1 nanoparticles. This seed-mediated co-reduction strategy produced monodisperse nanoparticles ideally suited for structure–activity studies. Furthermore, the study of their growth mechanism provides insights into the size dependence of disorder–order transformations of bimetallic alloys at the nanoscale, which should enable the design of synthetic strategies toward other intermetallic systems.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [2]
  1. Indiana Univ., Bloomington, IN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1254068
Grant/Contract Number:
AC05-00OR22725; SC0010489
Type:
Published Article
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 10; Journal Issue: 6; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE; 30 DIRECT ENERGY CONVERSION; seed-mediated co-reduction; nanocrystals; electrocatalysis; disorder-order transformation