多晶CeO <sub>2的</sub>拉曼光谱：密度泛函理论研究,The Journal of Physical Chemistry C

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多晶CeO _2的拉曼光谱：密度泛函理论研究
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-09-13 00:00:00 , DOI: 10.1021/acs.jpcc.7b06643
Christian Schilling ₁ , Alexander Hofmann ₂ , Christian Hess ₁ , M. Verónica Ganduglia-Pirovano ₃

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氧化铈是催化和燃料电池应用的重要材料。我们提供了从头算密度泛函理论（DFT）研究二氧化铈的振动特性，重点是多晶粉末样品的拉曼光谱的解释，其振动带在250至1200 cm ^–1的频率范围内。模型系统包括氧化的CeO ₂以及还原的CeO _{2– x}和Ce ₂ O ₃块状材料，以及CeO ₂（111）和缺氧的CeO _{2– x}（111）表面。实验观察到的在250 cm ^–1处的谱带被指定为纯CeO ₂的表面模式（111）面，在与我们的二氧化铈（铈的拉曼光谱协议₂）粉末具有不同晶体尺寸（Filtschew，A .;霍夫曼，K。;赫斯，C.，J.的PHY。化学式Ç 2016，120，6694 ）。简化的模型系统在480–600 cm ^–1的区域中显示出特征性的振动带，这与氧缺陷的存在和Ce ³⁺离子的减少有关。在800至900 cm ^–1之间的高频区域，特征过氧化物（O ₂^2–）获得了氧化的和有缺陷的二氧化铈表面的拉伸振动，并且对过氧化物覆盖率的系统研究为过氧化物拉伸模式的位置与其吸附几何形状和浓度之间的相关性提供了基础。本理论分析允许对多晶二氧化铈的实验拉曼光谱进行一致的描述。概述的方法可作为描述其他金属氧化物振动特性的参考。

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Raman Spectra of Polycrystalline CeO2: A Density Functional Theory Study

Cerium oxide is an important material for catalytic and fuel cell applications. We present an ab initio density functional theory (DFT) study of the vibrational properties of ceria focusing on the interpretation of Raman spectra of polycrystalline powder samples, with vibrational bands in the frequency region between 250 and 1200 cm^–1. The model systems include the oxidized CeO₂ as well as the reduced CeO_2–x and Ce₂O₃ bulk materials together with the CeO₂(111) and oxygen defective CeO_2–x(111) surfaces. The experimentally observed band at 250 cm^–1 is assigned to a surface mode of the clean CeO₂(111) surface, in agreement with our Raman spectra of ceria (CeO₂) powders with varying crystal size (Filtschew, A.; Hofmann, K.; Hess, C., J. Phys. Chem. C 2016, 120, 6694). The reduced model systems display signature vibrational bands in the 480–600 cm^–1 region associated with the presence of oxygen defects and reduced Ce³⁺ ions. In the high-frequency region between 800 and 900 cm^–1, characteristic peroxide (O₂^2–) stretching vibrations at the oxidized and defective ceria surfaces are obtained, and a systematic study with respect to the peroxide coverage provides the basis for a correlation between the position of the peroxide stretching mode and its adsorption geometry and concentration. The present theoretical analysis allows for a consistent description of the experimental Raman spectra of polycrystalline ceria. The outlined approach serves as a reference for the description of vibrational properties of other metal oxides.

更新日期：2017-09-14

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