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首页> 外文期刊>Applied Surface Science >Electron-accepting surface properties of ceria-(praseodymia)-zirconia solids modified by Y3+ or La3+ studied by paramagnetic probe method
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Electron-accepting surface properties of ceria-(praseodymia)-zirconia solids modified by Y3+ or La3+ studied by paramagnetic probe method

机译：Y3 +或La3 +修饰的二氧化铈-（氧化锆）-氧化锆固体的电子接受表面性质的顺磁探针法研究

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EPR paramagnetic probe method with 2,2,6,6-tetramethylpiperidin-N-oxyl (TEMPO) as a probe has been applied to study of electron-accepting properties of the surface of (Y, La-0.1)CexZr1-xO2-y (x = 0.1-0.7), Y0.1Pr0.3Zr0.6O2-y and Y0.1Pr0.15Ce0.15Zr0.7O2-y mixed oxides. Two types of acceptor sites-coordinatively unsaturated (cus) cations Zr4+ and Ce4+-have been revealed on the CeO2-ZrO2 surface after thermovacuum treatment (820 K). The relative amounts and "strength" of these centers were evaluated on the basis of EPR spectra analysis. An introduction of trivalent Y3+ or La3+ cations reduces the amount of electron-acceptor sites belonging to cerium cations, stabilizing ones as Ce3+. A formation of very strong electron-accepting sites (Pr4+ cus cations) able to form charge transfer complexes with adsorbed TEMPO on the surface of praseodymia-containing samples after thermovacuum treatment was found out. At the same time electron-accepting ability of Zr4+ cationic sites on Y0.1Pr0.3Zr0.6O2-y and Y0.1Pr0.15Ce0.15Zr0.7O2-y surfaces decreases in comparison with ceria-zirconia one. The generally used IR spectroscopy technique with CO as a probe molecule appeared to be considerably less informative for such systems characterization, due to their high catalytic activity to carbon monoxide. A formation of paramagnetic Zr3+ ions in ceria-zirconia mixed oxides has been investigated by EPR spectroscopy technique. The different states of this paramagnetic ion are realized in the complex oxides depending on Ce/Zr ratio. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 44]
机译：以2,2,6,6-四甲基哌啶-N-氧基（TEMPO）为探针的EPR顺磁探针法已被用于研究（Y，La-0.1）CexZr1-xO2-y表面的电子接受特性（x ＝ 0.1-0.7），Y0.1Pr0.3Zr0.6O2-y和Y0.1Pr0.15Ce0.15Zr0.7O2-y混合氧化物。热真空处理（820 K）后，在CeO2-ZrO2表面发现了两种类型的受体位点-配位不饱和（cus）阳离子Zr4 +和Ce4 +。这些中心的相对数量和“强度”是根据EPR光谱分析进行评估的。三价Y3 +或La3 +阳离子的引入减少了属于铈阳离子的电子受体位点的数量，使Ce3 +稳定。发现在热真空处理后，形成了非常强的电子接受位点（Pr4 + cus阳离子），该位点能够与吸附的TEMPO形成吸附电荷的复合物，并与吸附的TEMPO形成电荷转移络合物。同时，与二氧化铈-氧化锆相比，Y0.1Pr0.3Zr0.6O2-y和Y0.1Pr0.15Ce0.15Zr0.7O2-y表面的Zr4 +阳离子位点的电子接受能力降低。由于其对一氧化碳的高催化活性，通常使用以CO作为探针分子的IR光谱技术对这类系统的表征缺乏足够的信息。通过EPR光谱技术研究了二氧化铈-氧化锆混合氧化物中顺磁性Zr3 +离子的形成。取决于Ce / Zr比，在复合氧化物中可以实现这种顺磁离子的不同状态。 （C）2002 Elsevier Science B.V.保留所有权利。 [参考：44]

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