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Title: Synthesis of Supported Pd 0 Nanoparticles from a Single-Site Pd 2+ Surface Complex by Alkene Reduction

Here, a surface metal–organic complex, (-AlO x)Pd(acac) (acac = acetylacetonate), is prepared by chemically grafting the precursor Pd(acac) 2 onto γ-Al 2O 3 in toluene at 25 °C. The resulting surface complex is characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and dynamic nuclear polarization surface-enhanced solid-state nuclear magnetic resonance spectroscopy (DNP SENS). This surface complex is a precursor in the direct synthesis of size-controlled Pd nanoparticles under mild reductive conditions and in the absence of additional stabilizers or pretreatments. Indeed, upon exposure to gaseous ethylene or liquid 1-octene at 25 °C, the Pd 2+ species is reduced to form Pd 0 nanoparticles with a mean diameter of 4.3 ± 0.6 nm, as determined by scanning transmission electron microscopy (STEM). These nanoparticles are catalytically relevant using the aerobic 1-phenylethanol oxidation as a probe reaction, with rates comparable to a conventional Pd/Al 2O 3 catalyst but without an induction period. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed reaction mass spectrometry (TPR-MS) reveal that the surface complex reduction with ethylene coproduces H 2, acetylene, and 1,3-butadiene. This process reasonably proceeds via an olefin activation/coordination/insertion pathway, followed by β-hydride elimination to generatemore » free Pd 0. Lastly, the well-defined nature of the single-site supported Pd 2+ precursor provides direct mechanistic insights into this unusual and likely general reductive process.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [1] ;  [4] ; ORCiD logo [4] ; ORCiD logo [3] ; ORCiD logo [1] ;  [5] ; ORCiD logo [6]
  1. Northwestern Univ., Evanston, IL (United States). Department of Chemistry
  2. Northwestern Univ., Evanston, IL (United States). Department of Chemical & Biological Engineering
  3. Northwestern Univ., Evanston, IL (United States). Department of Materials Science & Engineering
  4. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  5. Northwestern Univ., Evanston, IL (United States). Department of Chemistry; Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences & Engineering Division
  6. Northwestern Univ., Evanston, IL (United States). Department of Chemistry and Department of Chemical & Biological Engineering
Publication Date:
Report Number(s):
IS-J-9596
Journal ID: ISSN 0897-4756
Grant/Contract Number:
AC02-07CH11358; FG02-03ER154757; AC02-06CH11357; FG02-03ER15457
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 30; Journal Issue: 3; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE
OSTI Identifier:
1427728