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Title: Spectroscopic Investigation of Surface-Dependent Acid–Base Property of Ceria Nanoshapes

Abstract

In addition to their well-known redox character, the acid-base property is another interesting aspect of ceria-based catalysts. Thus, the effect of surface structure on the acid-base property of ceria was studied in detail by utilizing ceria nanocrystals with different morphologies (cubes, octahedra and rods) that exhibit crystallographically well-defined surface facets. The nature, type, strength and amount of acid and base sites on these ceria nanoshapes were investigated via in situ IR spectroscopy combined with various probe molecules. Pyridine adsorption shows the presence of Lewis acid sites (Ce cations) on the ceria nanoshapes. These Lewis acid sites are relatively weak and similar in strength among the three nanoshapes according to the probing by both pyridine and acetonitrile. Both Br nsted (hydroxyl group) and Lewis (surface lattice oxygen) base sites are present on the ceria nanoshapes as probed by CO2 adsorption. CO2 and chloroform adsorption indicate that the strength and amount of the Lewis base sites are shape dependent: rods > cubes > octahedra. Moreover, the weak and strong surface dependence of the acid and base sites, respectively, are a result of interplay between the surface structure dependent coordination unsaturation status of the Ce cations and O anions and the amount ofmore » defect sites on the three ceria nanoshapes. Furthermore, it was found that the nature of the acid-base sites of ceria can be impacted by impurities, such as Na and P residues that result from their use as structure-directing reagent in the hydrothermal synthesis of the ceria nanocrystals. Finally, our observation calls for precaution in interpreting the catalytic behavior of nanoshaped ceria where trace impurities may be present.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
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)
OSTI Identifier:
1185894
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 119; Journal Issue: 13; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Wu, Zili, Mann, Amanda K. P., Li, Meijun, and Overbury, Steven H. Spectroscopic Investigation of Surface-Dependent Acid–Base Property of Ceria Nanoshapes. United States: N. p., 2015. Web. doi:10.1021/acs.jpcc.5b00859.
Wu, Zili, Mann, Amanda K. P., Li, Meijun, & Overbury, Steven H. Spectroscopic Investigation of Surface-Dependent Acid–Base Property of Ceria Nanoshapes. United States. doi:10.1021/acs.jpcc.5b00859.
Wu, Zili, Mann, Amanda K. P., Li, Meijun, and Overbury, Steven H. Thu . "Spectroscopic Investigation of Surface-Dependent Acid–Base Property of Ceria Nanoshapes". United States. doi:10.1021/acs.jpcc.5b00859. https://www.osti.gov/servlets/purl/1185894.
@article{osti_1185894,
title = {Spectroscopic Investigation of Surface-Dependent Acid–Base Property of Ceria Nanoshapes},
author = {Wu, Zili and Mann, Amanda K. P. and Li, Meijun and Overbury, Steven H.},
abstractNote = {In addition to their well-known redox character, the acid-base property is another interesting aspect of ceria-based catalysts. Thus, the effect of surface structure on the acid-base property of ceria was studied in detail by utilizing ceria nanocrystals with different morphologies (cubes, octahedra and rods) that exhibit crystallographically well-defined surface facets. The nature, type, strength and amount of acid and base sites on these ceria nanoshapes were investigated via in situ IR spectroscopy combined with various probe molecules. Pyridine adsorption shows the presence of Lewis acid sites (Ce cations) on the ceria nanoshapes. These Lewis acid sites are relatively weak and similar in strength among the three nanoshapes according to the probing by both pyridine and acetonitrile. Both Br nsted (hydroxyl group) and Lewis (surface lattice oxygen) base sites are present on the ceria nanoshapes as probed by CO2 adsorption. CO2 and chloroform adsorption indicate that the strength and amount of the Lewis base sites are shape dependent: rods > cubes > octahedra. Moreover, the weak and strong surface dependence of the acid and base sites, respectively, are a result of interplay between the surface structure dependent coordination unsaturation status of the Ce cations and O anions and the amount of defect sites on the three ceria nanoshapes. Furthermore, it was found that the nature of the acid-base sites of ceria can be impacted by impurities, such as Na and P residues that result from their use as structure-directing reagent in the hydrothermal synthesis of the ceria nanocrystals. Finally, our observation calls for precaution in interpreting the catalytic behavior of nanoshaped ceria where trace impurities may be present.},
doi = {10.1021/acs.jpcc.5b00859},
journal = {Journal of Physical Chemistry. C},
number = 13,
volume = 119,
place = {United States},
year = {Thu Mar 12 00:00:00 EDT 2015},
month = {Thu Mar 12 00:00:00 EDT 2015}
}

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