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Title: Size- and Support-Dependent Evolution of the Oxidation State and Structure by Oxidation of Subnanometer Cobalt Clusters

Abstract

Size-selected subnanometer cobalt clusters with 4, 7 and 27 cobalt atoms supported on amorphous alumina and ultrananocrystalline diamond (UNCD) surfaces were oxidized after exposure to ambient air. Grazing incidence X-ray absorption near edge spectroscopy (GIXANES) and near edge X-ray absorption fine structure (NEXAFS) used to characterize the clusters revealed a strong dependency of the oxidation state and structure of the clusters on the surface. A dominant Co2+ phase was identified in all samples. However, form XANES analysis, on UNCD about 10% fraction of Co0 phase was identified for all three cluster sizes and about 30% and 12% fraction of Co3+ phase in 4, 7 and 27 atoms, respectively. In the alumina-supported clusters, the dominating Co2+ component was attributed to cobalt aluminate, indicative of a very strong binding to the support. NEXAFS showed that in addition to strong binding of the clusters to alumina, their structure in great extent follows the tetrahedral morphology of the support. The supported clusters of all three sizes were found resistant to agglomeration when exposed to reactive gases at elevated temperatures and atmospheric pressure.

Authors:
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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:
1357058
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 118; Journal Issue: 37; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

Yin, Chunrong, Zheng, Fan, Lee, Sungsik, Guo, Jinghua, Wang, Wei-Cheng, Kwon, Gihan, Vajda, Viktor, Wang, Hsien-Hau, Lee, Byeongdu, DeBartolo, Janae, Seifert, Sönke, Winans, Randall E., and Vajda, Stefan. Size- and Support-Dependent Evolution of the Oxidation State and Structure by Oxidation of Subnanometer Cobalt Clusters. United States: N. p., 2014. Web. doi:10.1021/jp501817u.
Yin, Chunrong, Zheng, Fan, Lee, Sungsik, Guo, Jinghua, Wang, Wei-Cheng, Kwon, Gihan, Vajda, Viktor, Wang, Hsien-Hau, Lee, Byeongdu, DeBartolo, Janae, Seifert, Sönke, Winans, Randall E., & Vajda, Stefan. Size- and Support-Dependent Evolution of the Oxidation State and Structure by Oxidation of Subnanometer Cobalt Clusters. United States. doi:10.1021/jp501817u.
Yin, Chunrong, Zheng, Fan, Lee, Sungsik, Guo, Jinghua, Wang, Wei-Cheng, Kwon, Gihan, Vajda, Viktor, Wang, Hsien-Hau, Lee, Byeongdu, DeBartolo, Janae, Seifert, Sönke, Winans, Randall E., and Vajda, Stefan. Thu . "Size- and Support-Dependent Evolution of the Oxidation State and Structure by Oxidation of Subnanometer Cobalt Clusters". United States. doi:10.1021/jp501817u.
@article{osti_1357058,
title = {Size- and Support-Dependent Evolution of the Oxidation State and Structure by Oxidation of Subnanometer Cobalt Clusters},
author = {Yin, Chunrong and Zheng, Fan and Lee, Sungsik and Guo, Jinghua and Wang, Wei-Cheng and Kwon, Gihan and Vajda, Viktor and Wang, Hsien-Hau and Lee, Byeongdu and DeBartolo, Janae and Seifert, Sönke and Winans, Randall E. and Vajda, Stefan},
abstractNote = {Size-selected subnanometer cobalt clusters with 4, 7 and 27 cobalt atoms supported on amorphous alumina and ultrananocrystalline diamond (UNCD) surfaces were oxidized after exposure to ambient air. Grazing incidence X-ray absorption near edge spectroscopy (GIXANES) and near edge X-ray absorption fine structure (NEXAFS) used to characterize the clusters revealed a strong dependency of the oxidation state and structure of the clusters on the surface. A dominant Co2+ phase was identified in all samples. However, form XANES analysis, on UNCD about 10% fraction of Co0 phase was identified for all three cluster sizes and about 30% and 12% fraction of Co3+ phase in 4, 7 and 27 atoms, respectively. In the alumina-supported clusters, the dominating Co2+ component was attributed to cobalt aluminate, indicative of a very strong binding to the support. NEXAFS showed that in addition to strong binding of the clusters to alumina, their structure in great extent follows the tetrahedral morphology of the support. The supported clusters of all three sizes were found resistant to agglomeration when exposed to reactive gases at elevated temperatures and atmospheric pressure.},
doi = {10.1021/jp501817u},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
issn = {1089-5639},
number = 37,
volume = 118,
place = {United States},
year = {2014},
month = {9}
}