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Title: Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–xPt x Clusters under H 2 and CO + H 2 Atmospheres

Abstract

In this study, Co 1–xPt x clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al 2O 3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged cluster samples were characterized by grazing-incidence X-ray absorption spectroscopy (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H 2 up to 225°C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the clusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the clusters. For example, a low Pt/Co ratio (x ≤ 0.5) facilitates the formation of Co(OH) 2, whereas a high Pt/Comore » ratio (x = 0.75) stabilizes the Co 3O 4 composition instead through the formation of a Co–Pt core–shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co 1–xPt x alloy clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less

Authors:
 [1];  [2];  [2];  [1];  [1];  [3];  [3];  [4];  [2];  [5]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  2. University Lyon & CNRS, Lyon (France). Institut Lumiere Matiere
  3. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
  4. Northwestern Univ., Evanston, IL (United States). Department of Mechanical Engineering
  5. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division and Nanoscience and Technology Division; Yale Univ., New Haven, CT (United States). Department of Chemical and Environmental Engineering; Univ. of Chicago, IL (United States). Institute for Molecular Engineering
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1352595
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 120; Journal Issue: 38; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, and Vajda, Stefan. Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co1–xPtx Clusters under H2 and CO + H2 Atmospheres. United States: N. p., 2016. Web. doi:10.1021/acs.jpcc.6b06483.
Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, & Vajda, Stefan. Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co1–xPtx Clusters under H2 and CO + H2 Atmospheres. United States. doi:10.1021/acs.jpcc.6b06483.
Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, and Vajda, Stefan. Thu . "Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co1–xPtx Clusters under H2 and CO + H2 Atmospheres". United States. doi:10.1021/acs.jpcc.6b06483. https://www.osti.gov/servlets/purl/1352595.
@article{osti_1352595,
title = {Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co1–xPtx Clusters under H2 and CO + H2 Atmospheres},
author = {Yang, Bing and Khadra, Ghassan and Tuaillon-Combes, Juliette and Tyo, Eric C. and Pellin, Michael J. and Reinhart, Benjamin and Seifert, Sönke and Chen, Xinqi and Dupuis, Veronique and Vajda, Stefan},
abstractNote = {In this study, Co1–xPtx clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al2O3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged cluster samples were characterized by grazing-incidence X-ray absorption spectroscopy (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H2 up to 225°C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the clusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the clusters. For example, a low Pt/Co ratio (x ≤ 0.5) facilitates the formation of Co(OH)2, whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co3O4 composition instead through the formation of a Co–Pt core–shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co1–xPtx alloy clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.},
doi = {10.1021/acs.jpcc.6b06483},
journal = {Journal of Physical Chemistry. C},
number = 38,
volume = 120,
place = {United States},
year = {Thu Aug 25 00:00:00 EDT 2016},
month = {Thu Aug 25 00:00:00 EDT 2016}
}

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