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Title: Diphosphine-Protected Au 22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal

Investigation of monodispersed and atomically-precise Au nanoclusters provides a route to understand the roles of coordination, size, and ligand effects in Au catalysis. We have explored the catalytic behavior of a newly-synthesized Au 22(L 8) 6 nanocluster (L = 1,8-bis(diphenylphosphino) octane) with in situ uncoordinated Au sites supported on TiO 2, CeO 2 and Al 2O 3. Stability of the supported Au 22 nanoclusters was probed structurally by EXAFS and HAADF-STEM, and their adsorption and reactivity for CO oxidation were investigated by IR absorption spectroscopy and temperature programed flow reaction. Low temperature CO oxidation activity was observed for the supported pristine Au 22(L 8) 6 nanoclusters without ligand removal. Isotopically labeled O 2 was used to demonstrate that the reaction pathway occurs through a redox mechanism, consistent with the observed support-dependent activity trend: CeO 2 > TiO 2 > Al 2O 3. Substantiated by density functional theory (DFT) calculations, we conclude that the uncoordinated Au sites in the intact Au 22(L 8) 6 nanoclusters are capable of adsorbing CO, activating O2 and promoting CO oxidation reaction. Thanks to the presence of the in situ coordination unsaturated Au atoms, this work is the first clear demonstration of a ligand-protected Au nanoclustermore » that are active for gas phase catalysis without the need of ligand removal.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [1] ;  [3] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of California, Riverside, CA (United States)
  3. Brown Univ., Providence, RI (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 10; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
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)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1360045

Wu, Zili, Hu, Guoxiang, Jiang, De-en, Mullins, David R., Zhang, Qianfan, Allard, Jr, Lawrence Frederick, Wang, Laisheng, and Overbury, Steven H.. Diphosphine-Protected Au22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal. United States: N. p., Web. doi:10.1021/acs.nanolett.6b03221.
Wu, Zili, Hu, Guoxiang, Jiang, De-en, Mullins, David R., Zhang, Qianfan, Allard, Jr, Lawrence Frederick, Wang, Laisheng, & Overbury, Steven H.. Diphosphine-Protected Au22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal. United States. doi:10.1021/acs.nanolett.6b03221.
Wu, Zili, Hu, Guoxiang, Jiang, De-en, Mullins, David R., Zhang, Qianfan, Allard, Jr, Lawrence Frederick, Wang, Laisheng, and Overbury, Steven H.. 2016. "Diphosphine-Protected Au22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal". United States. doi:10.1021/acs.nanolett.6b03221. https://www.osti.gov/servlets/purl/1360045.
@article{osti_1360045,
title = {Diphosphine-Protected Au22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal},
author = {Wu, Zili and Hu, Guoxiang and Jiang, De-en and Mullins, David R. and Zhang, Qianfan and Allard, Jr, Lawrence Frederick and Wang, Laisheng and Overbury, Steven H.},
abstractNote = {Investigation of monodispersed and atomically-precise Au nanoclusters provides a route to understand the roles of coordination, size, and ligand effects in Au catalysis. We have explored the catalytic behavior of a newly-synthesized Au22(L8)6 nanocluster (L = 1,8-bis(diphenylphosphino) octane) with in situ uncoordinated Au sites supported on TiO2, CeO2 and Al2O3. Stability of the supported Au22 nanoclusters was probed structurally by EXAFS and HAADF-STEM, and their adsorption and reactivity for CO oxidation were investigated by IR absorption spectroscopy and temperature programed flow reaction. Low temperature CO oxidation activity was observed for the supported pristine Au22(L8)6 nanoclusters without ligand removal. Isotopically labeled O2 was used to demonstrate that the reaction pathway occurs through a redox mechanism, consistent with the observed support-dependent activity trend: CeO2 > TiO2 > Al2O3. Substantiated by density functional theory (DFT) calculations, we conclude that the uncoordinated Au sites in the intact Au22(L8)6 nanoclusters are capable of adsorbing CO, activating O2 and promoting CO oxidation reaction. Thanks to the presence of the in situ coordination unsaturated Au atoms, this work is the first clear demonstration of a ligand-protected Au nanocluster that are active for gas phase catalysis without the need of ligand removal.},
doi = {10.1021/acs.nanolett.6b03221},
journal = {Nano Letters},
number = 10,
volume = 16,
place = {United States},
year = {2016},
month = {9}
}