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Title: Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2O 4 spinel in oxidizing atmosphere

With the capability of MgAl 2O 4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated in this paper, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2 nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H 2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. Finally, a dynamic stabilization mechanism involving wetting/nucleation seems to be responsible for the evolution of surface compositions upon cyclic oxidizing and reducing thermal treatments.
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Washington State Univ., Pullman, WA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1566-7367; PII: S1566736717300201
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Catalysis Communications
Additional Journal Information:
Journal Volume: 93; Journal ID: ISSN 1566-7367
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
36 MATERIALS SCIENCE; spinel; platinum; iridium; nano-alloy stabilization
OSTI Identifier: