Ce1-xTbxO2-δ复合氧化物氧缺位的拉曼光谱研究

高等学校化学学报 ›› 2009, Vol. 30 ›› Issue (8): 1645.

Ce_1-xTb_xO_2-δ复合氧化物氧缺位的拉曼光谱研究

郭明, 普志英, 毕庆员, 鲁继青, 罗孟飞

浙江师范大学物理化学研究所, 浙江省固体表面反应化学重点实验室, 金华 321004

收稿日期:2009-03-18 出版日期:2009-08-10 发布日期:2009-08-10
通讯作者: 罗孟飞, 男, 博士, 研究员, 主要从事催化研究. E-mail: mengfeiluo@zjnu.cn
基金资助:
国家自然科学基金(批准号: 20473075)资助.

Raman Spectroscopic Study of Oxygen Vacancies in Ce_1-xTb_xO_2-δ Mixed Oxides

GUO Ming, PU Zhi-Ying, BI Qing-Yuan, LU Ji-Qing, LUO Meng-Fei*

Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Jinhua 321004, China

Received:2009-03-18 Online:2009-08-10 Published:2009-08-10
Contact: LUO Meng-Fei. E-mail: mengfeiluo@zjnu.cn
Supported by:
国家自然科学基金(批准号: 20473075)资助.

摘要/Abstract

摘要：

采用溶胶-凝胶法制备了Ce_1-xTb_xO_2-δ复合氧化物, 利用不同Raman激发波长(514和785 nm), 结合X射线衍射(XRD)、氢气-程序升温还原(H₂-TPR)和氧气-程序升温脱附(O₂-TPD)表征, 考察了Ce_1-xTb_xO_2-δ复合氧化物在O₂, He和H₂气氛下氧缺位的原位变化情况和CeO₂的F_2g特征Raman峰位的偏移. 实验结果表明, 随着Tb掺杂量的提高, 由于晶胞收缩使得CeO₂的F_2g特征Raman振动峰发生蓝移. 514 nm Raman激发波长反映了催化剂的表面信息, 而785 nm激发波长反映了整体信息. 正是由于表面和整体变化的不一致, 造成原位Raman实验过程中氧缺位浓度变化趋势的不同. 在He和H₂气氛下, 由于温度升高时伴随着Ce_1-xTb_xO_2-δ中O₂气的脱出, 使复合氧化物的微观结构发生改变, 以致Ce_0.9Tb_0.1O_2-δ中的氧缺位浓度(A₅₈₇/A₄₆₅)在785 nm激发波长下出现先升高后下降的现象.

关键词: 原位拉曼光谱; Ce_1-xTb_xO_2-δ复合氧化物; 氧缺位

Abstract:

A series of Ce_1-xTb_xO_2-δ mixed oxides were prepared by a sol-gel method. In situ Raman spectroscopy combined with X-ray diffraction(XRD), H₂-temperature programmed reduction(H₂-TPR) and O₂-temperature programmed desorption(O₂-TPD) were used to analyze oxygen vacancies in the mixed oxides under different atmospheres(O₂, He, and H₂) with 514 and 785 nm excitation laser lines and the blue shift of the F_2g vibration mode of CeO₂. The results show that increasing Tb content in the sample result in the blue shift of F_2g vibration mode of CeO₂ because of dominant effect of the shrinking of the crystal. Furthermore, the difference in the changing trend of oxygen vacancies is due to the different Raman excitation laser lines. 514 nm excitation laser line can provide the surface information, while 785 nm excitation laser line can get the whole information of the sample. The A₅₈₇/A₄₆₅ ratio reflecting the oxygen vacancies shows an inflexion under He and H₂ atmospheres could be explained by the change in microstructure of the sample along with the release of O₂ during the heating process.

Key words: In situ Raman spectroscopy; Ce_1-xTb_xO_2-δ mixed oxide; Oxygen vacancy

TrendMD:

郭明, 普志英, 毕庆员, 鲁继青, 罗孟飞. Ce_1-xTb_xO_2-δ复合氧化物氧缺位的拉曼光谱研究. 高等学校化学学报, 2009, 30(8): 1645.

GUO Ming, PU Zhi-Ying, BI Qing-Yuan, LU Ji-Qing, LUO Meng-Fei*. Raman Spectroscopic Study of Oxygen Vacancies in Ce_1-xTb_xO_2-δ Mixed Oxides. Chem. J. Chinese Universities, 2009, 30(8): 1645.

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