Ceria and Its Defect Structure: New Insights from a Combined Spectroscopic Approach
Ceria and Its Defect Structure: New Insights from a Combined Spectroscopic Approach
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DOI：
10.1021/acs.jpcc.6b00959
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发表时间：
2016-03-31
影响因子：
3.7
通讯作者：
Hess, Christian
中科院分区：
文献类型：
--
作者：
Filtschew, Anastasia;Hofmann, Kathrin;Hess, Christian
二氧化铈是一种用于各种催化和燃料电池应用的令人感兴趣的组分。在本文所述的研究中，使用XRD、N-2吸附-脱附和光学光谱（拉曼、DRIFTS、UV-vis）详细研究了十种不同的商业氧化铈样品以及合成氧化铈样品的（缺陷）结构和特征性质。研究表明，表面缺陷特征（拉曼，DRIFTS）以及体缺陷（拉曼，UV-vis）的相关性。在约250 cm（-1）处的拉曼特征被证明与表面缺陷有关，而不是如文献中所述的2 TA振动。紫外-可见带隙值和拉曼体缺陷的存在之间的相关性建立的基础上观察到的带隙能量的减少，随着缺陷的数量增加。详细的拉曼分析表明，经常提到的由F-2g拉曼特征的半宽确定晶体尺寸的线性方程是错误的，因为F-2g半宽取决于二氧化铈体缺陷。除了这些普遍的意见，不同的性质取决于合成条件进行了观察。特别是，它表明，氧化铈缺陷的类型和数量的影响，不仅由晶体尺寸，但也由制备方法。
Ceria is an interesting component for a variety of catalytic and fuel cell applications. In the study described here, ten different commercial ceria samples as well as synthesized ceria samples were investigated in detail regarding their (defect) structure and characteristic properties using XRD, N-2 adsorption-desorption, and optical spectroscopy (Raman, DRIFTS, UV-vis). The investigations revealed correlations of surface defect features (Raman, DRIFTS) as well as those of bulk defects (Raman, UV-vis). The Raman feature at around 250 cm(-1) was demonstrated to be related to surface defects rather than a 2TA vibration as described in the literature. A correlation between UV-vis band gap values and the presence of Raman bulk defects was established based on the observed decrease of the band gap energy with increasing number of defects. Detailed Raman analysis revealed that the frequently mentioned linear equation for the determination of the crystal size from the half-width of the F-2g Raman feature is erroneous, since the F-2g half-width depends on ceria bulk defects. Apart from these universal observations, differences in the properties depending on synthesis conditions were observed. In particular, it is shown that the type and quantity of ceria defects are influenced not only by crystal size but also by the preparation method.