Oxygen Uptake of Tb–CeO2: Analysis of Ce3+ and Oxygen Vacancies

In response to concerns about the world’s generation of greenhouse gases, there are incentives to develop lower energy alternatives to cryogenic air separation. Oxygen sorbents are one such alternative in which high oxygen uptakes are achieved through engineering materials with a high number of oxyg...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2016-07, Vol.120 (26), p.14382-14389
Main Authors: D’Angelo, Anita M, Liu, Amelia C. Y, Chaffee, Alan L
Format: Article
Language:English
Online Access:Get full text
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Summary:In response to concerns about the world’s generation of greenhouse gases, there are incentives to develop lower energy alternatives to cryogenic air separation. Oxygen sorbents are one such alternative in which high oxygen uptakes are achieved through engineering materials with a high number of oxygen vacancy defects. For a series of Tb–CeO2 mixed oxides, the oxygen uptake was determined using thermogravimetric analysis (TGA). Electron energy loss spectroscopy (EELS) was used to investigate the relative oxygen vacancy concentration and complement those findings obtained using TGA. Gas switching experiments conducted at 700 °C show that a higher oxygen uptake was obtained when 30% Tb was incorporated into the lattice (76 μmol·g–1) in comparison to when 10% Tb was introduced (21 μmol·g–1). The O I B/I C ratio, indicative of oxygen vacancies, was found to increase with increasing Tb content, and Raman spectroscopy demonstrated that these defects were introduced with the addition of Tb. The increase in oxygen uptake with increasing Tb was attributed to the introduction of Tb generating vacancies and increasing the materials reduction ability. It was also observed that for a standard CeO2 sample the Ce I M5/I M4 and O I B /I C ratios varied depending on whether spectra were obtained from a collection of smaller crystallites or a single crystallite.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.6b04063