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

Abstract

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 duster 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 degrees 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 dusters 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 dusters. 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 Co3O4more » 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 dusters. The obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division
OSTI Identifier:
1392497
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 120; Journal Issue: 38
Country of Publication:
United States
Language:
English

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 Co 1–x Pt x Clusters under H 2 and CO + H 2 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 Co 1–x Pt x Clusters under H 2 and CO + H 2 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 Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres". United States. doi:10.1021/acs.jpcc.6b06483.
@article{osti_1392497,
title = {Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 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 = {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 duster 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 degrees 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 dusters 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 dusters. 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 dusters. 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 Sep 29 00:00:00 EDT 2016},
month = {Thu Sep 29 00:00:00 EDT 2016}
}