Defect Chemistry of Oxide Nanomaterials with High Surface Area: Ordered Mesoporous Thin Films of the Oxygen Storage Catalyst CeO2-ZrO2
Defect Chemistry of Oxide Nanomaterials with High Surface Area: Ordered Mesoporous Thin Films of the Oxygen Storage Catalyst CeO2-ZrO2
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DOI：
10.1021/nn400255w
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发表时间：
2013-04-01
期刊：
影响因子：
17.1
通讯作者：
Janek, Juergen
中科院分区：
文献类型：
--
作者：
Hartmann, Pascal;Brezesinski, Torsten;Janek, Juergen
本文报道了一系列有序介孔氧化铈-氧化锆（CexZr 1-xO 2，简称mp-CZO）薄膜的电输运性质，该薄膜具有直径为（17 +/- 2）nm的孔和纳米晶壁的立方结构。样品在整个范围内的组合物，包括裸CeO 2和ZrO 2，通过模板策略使用大的二嵌段共聚物KLE作为结构导向剂制造。通过扫描和透射电子显微镜、掠入射小角X射线散射、X射线光电子能谱和飞行时间二次离子质谱的组合，分析了介孔材料的纳米级结构和化学组成。使用阻抗谱测量作为膜组成、温度和氧分压的函数的总电导率。在这项工作中制备的CeO 2-ZrO 2的介孔固溶体表现出更高的稳定性，对热成熟比两个二元氧化物，使它们成为理想的模型系统，研究在高温下的电荷传输性能和储氧。我们发现，nanoaystalline mp-CZO薄膜的氧化还原性能显着不同的散装CZO材料在文献中报道，因此，提出了一个缺陷的表面区域的化学模型。
Herein we report the electrical transport properties of a series of ordered mesoporous ceria-zirconia (CexZr1-xO2, referred to as mp-CZO) thin films with both a cubic structure of (17 +/- 2) nm diameter pores and nanocrystalline walls. Samples over the whole range of composition, including bare CeO2 and ZrO2, were fabricated by templating strategies using the large diblock copolymer KLE as the structure-directing agent. Both the nanoscale structure and the chemical composition of the mesoporous materials were analyzed by a combination of scanning and transmission electron microscopy, grazing incidence small-angle X-ray scattering, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The total conductivity as a function of the film composition, temperature, and oxygen partial pressure was measured using impedance spectroscopy. The mesoporous solid solutions of CeO2-ZrO2 prepared in this work showed a higher stability against thermal ripening than both binary oxides, making them ideal model systems to study both the charge transport properties and the oxygen storage at elevated temperatures. We find that the redox properties of nanoaystalline mp-CZO thin films differ significantly from those of bulk CZO materials reported in the literature and, therefore, propose a defect chemical model of surface regions.