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

详细信息    查看全文

• 作者：Anita M. D’Angelo ; Amelia C. Y. Liu ; Alan L. Chaffee
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：July 7, 2016
• 年：2016
• 卷：120
• 期：26
• 页码：14382-14389
• 全文大小：423K
• 年卷期：0
• ISSN：1932-7455

文摘

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.