Thermal Stability and Dispersion Behavior of Nanostructured CexZr1−xO2 Mixed Oxides over Anatase-TiO2: A Combined Study of CO Oxidation and Characterization by XRD, XPS, TPR, HREM, and UV−Vis DRS
Thermal Stability and Dispersion Behavior of Nanostructured CexZr1−xO2 Mixed Oxides over Anatase-TiO2: A Combined Study of CO Oxidation and Characterization by XRD, XPS, TPR, HREM, and UV−Vis DRS
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DOI：
10.1021/ie8012677
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发表时间：
2009-01
影响因子：
4.2
通讯作者：
B. M. Reddy;P. Bharali;P. Saikia;G. Thrimurthulu;Yusuke Yamada;Tetsuhiko Kobayashi
中科院分区：
文献类型：
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作者：
B. M. Reddy;P. Bharali;P. Saikia;G. Thrimurthulu;Yusuke Yamada;Tetsuhiko Kobayashi
研究了用沉积共沉淀法制备的纳米复合氧化物CexZr1TiO2xO2在锐钛矿型−载体上的热稳定性和分散行为。为了比较，我们还用共沉淀法合成了无担载的CexZr1-−-xO2混合氧化物。采用X射线衍射仪、高分辨电子显微镜、X射线光电子能谱、UV−可见漫反射光谱和程序升温还原技术对样品的结构和形貌进行了表征。X射线衍射分析表明，773K时，Ce0.75Zr0.25O2为立方相，高温下Ce0.75Zr0.25O2晶格中掺入了更多的锆离子。高分辨电子显微镜分析表明，773K时，Ce-−-Zr纳米氧化物在锐钛矿型二氧化钛载体上的尺寸为3-−-5 nm，在较高的温度下，Ce-TiO2Zr纳米氧化物的尺寸略有增加。
A study has been undertaken on the thermal stability and dispersion behavior of nanostructured CexZr1−xO2 mixed oxides over anatase-TiO2 support, synthesized by a deposition coprecipitation method and subjected to heat treatments at different temperatures. An unsupported CexZr1−xO2 mixed oxide was also synthesized by coprecipitation method for the purpose of comparison. The structural/morphological characterization was performed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HREM), X-ray photoelectron spectroscopy (XPS), UV−visible diffuse reflectance spectroscopy (UV−vis DRS), and temperature-programmed reduction (TPR) techniques. XRD measurements revealed the presence of cubic Ce0.75Zr0.25O2 phase at 773 K and incorporation of more zirconium into the ceria lattice at higher temperatures. HREM analysis conformed highly dispersed Ce−Zr nano-oxides over anatase-TiO2 support having the sizes in the range of 3−5 nm at 773 K. At higher temperatures, a slight increase in the c...