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Title: Microwave-Assisted Synthesis of Classically Immiscible Ag–Ir Alloy Nanoparticle Catalysts

Abstract

In this work, we present the synthesis of Ag–Ir alloys in the form of solid-solution nanoparticles (NPs). Ag and Ir are classically immiscible in the bulk and therefore the physical properties of Ag–Ir alloys are unknown. A convenient microwave-assisted, solution-phase method that employs readily available Ag(NO 3) and IrCl 3 precursors enables the preparation of small (2.5–5.5 nm) Ag–IrNPs with alloyed structures. Ag $x$Ir (100–$x$)NPs can be obtained by this method between $x$ = 6–31. The Ag–IrNPs resist dealloying upon heating up to 300 °C. Ir-rich Ag–IrNPs dispersed on amorphous silica are significantly more active gas-phase alkene hydrogenation catalysts than pure IrNPs. Density functional theory (DFT) and theoretical modeling studies reveal that the Ag–IrNPs—which are consistently larger than monometallic IrNPs prepared under the same conditions—have comparatively fewer strong H-binding edge sites. This promotes faster H atom transfer to coadsorbed alkenes. Ag–IrNPs supported on amorphous Co 3O 4 show a linear composition dependence in the selective hydrogenation of C$=$O versus C$=$C bonds: more Ag-rich Ag–IrNPs are more selective toward C$=$O hydrogenation of the α,β-unsaturated aldehyde crotonaldehyde, yielding the industrially desirable crotyl alcohol. Furthermore, deposition of Ag–IrNPs inside Co 3O 4 mesopores results in an additional ~56% selectivity enhancement.

Authors:
 [1];  [1]; ORCiD logo [2]; ORCiD logo [3];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Univ. of Texas, Austin, TX (United States). Dept. of Chemistry
  2. Univ. of Texas, Austin, TX (United States). Texas Materials Inst.
  3. Univ. of Texas, Austin, TX (United States). Dept. of Chemistry; Nanjing Univ., Nanjing, Jiangsu (China). School of Environment
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE
OSTI Identifier:
1543703
Resource Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 8; Journal Issue: 12; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
chemistry; metallic nanoparticles; alloy nanoparticles; microwave synthesis; heterogeneous catalysis; crotonaldehyde hydrogenation; silver; iridium

Citation Formats

Guo, Hongyu, Li, Hao, Jarvis, Karalee, Wan, Haiqin, Kunal, Pranaw, Dunning, Samuel G., Liu, Yulu, Henkelman, Graeme, and Humphrey, Simon M. Microwave-Assisted Synthesis of Classically Immiscible Ag–Ir Alloy Nanoparticle Catalysts. United States: N. p., 2018. Web. doi:10.1021/acscatal.8b02103.
Guo, Hongyu, Li, Hao, Jarvis, Karalee, Wan, Haiqin, Kunal, Pranaw, Dunning, Samuel G., Liu, Yulu, Henkelman, Graeme, & Humphrey, Simon M. Microwave-Assisted Synthesis of Classically Immiscible Ag–Ir Alloy Nanoparticle Catalysts. United States. doi:10.1021/acscatal.8b02103.
Guo, Hongyu, Li, Hao, Jarvis, Karalee, Wan, Haiqin, Kunal, Pranaw, Dunning, Samuel G., Liu, Yulu, Henkelman, Graeme, and Humphrey, Simon M. Wed . "Microwave-Assisted Synthesis of Classically Immiscible Ag–Ir Alloy Nanoparticle Catalysts". United States. doi:10.1021/acscatal.8b02103. https://www.osti.gov/servlets/purl/1543703.
@article{osti_1543703,
title = {Microwave-Assisted Synthesis of Classically Immiscible Ag–Ir Alloy Nanoparticle Catalysts},
author = {Guo, Hongyu and Li, Hao and Jarvis, Karalee and Wan, Haiqin and Kunal, Pranaw and Dunning, Samuel G. and Liu, Yulu and Henkelman, Graeme and Humphrey, Simon M.},
abstractNote = {In this work, we present the synthesis of Ag–Ir alloys in the form of solid-solution nanoparticles (NPs). Ag and Ir are classically immiscible in the bulk and therefore the physical properties of Ag–Ir alloys are unknown. A convenient microwave-assisted, solution-phase method that employs readily available Ag(NO3) and IrCl3 precursors enables the preparation of small (2.5–5.5 nm) Ag–IrNPs with alloyed structures. Ag$x$Ir(100–$x$)NPs can be obtained by this method between $x$ = 6–31. The Ag–IrNPs resist dealloying upon heating up to 300 °C. Ir-rich Ag–IrNPs dispersed on amorphous silica are significantly more active gas-phase alkene hydrogenation catalysts than pure IrNPs. Density functional theory (DFT) and theoretical modeling studies reveal that the Ag–IrNPs—which are consistently larger than monometallic IrNPs prepared under the same conditions—have comparatively fewer strong H-binding edge sites. This promotes faster H atom transfer to coadsorbed alkenes. Ag–IrNPs supported on amorphous Co3O4 show a linear composition dependence in the selective hydrogenation of C$=$O versus C$=$C bonds: more Ag-rich Ag–IrNPs are more selective toward C$=$O hydrogenation of the α,β-unsaturated aldehyde crotonaldehyde, yielding the industrially desirable crotyl alcohol. Furthermore, deposition of Ag–IrNPs inside Co3O4 mesopores results in an additional ~56% selectivity enhancement.},
doi = {10.1021/acscatal.8b02103},
journal = {ACS Catalysis},
number = 12,
volume = 8,
place = {United States},
year = {2018},
month = {10}
}

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