Shape-Dependent Activity of Ceria in Soot Combustion
Shape-Dependent Activity of Ceria in Soot Combustion
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DOI：
10.1021/cs400850r
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发表时间：
2014-01-01
期刊：
影响因子：
12.9
通讯作者：
Trovarelli, Alessandro
中科院分区：
文献类型：
--
作者：
Aneggi, Eleonora;Wiater, Dawid;Trovarelli, Alessandro
本研究采用水热法制备了一系列常规的多晶CeO_2和单晶CeO_3纳米棒、纳米立方体，并用X射线衍射仪、扫描电子显微镜、高分辨电子显微镜、比表面积、程序升温还原和储氧量等测试手段对其结构、结构和形貌进行了研究。根据HRTEM，它们的特征是暴露在不同的表面：纳米立方体的{100}表面；纳米棒的{100}、{110}和部分{111}；以及传统多晶CeO2的主要{11 1}，其形貌以{111}封闭的八面体颗粒为主。活性更强的暴露表面的存在对煤烟氧化反应产生了积极的影响，与传统的CeO2相比，纳米形状材料的活性有所增加。热老化虽然对表面积不利，但通过促进边和角的不规则截断以及在所有晶体形状中形成更多活性表面组合来影响形貌。从立方体或八面体粒子开始的热处理很可能会导致类似粒子几何形状的形成，其活性取决于暴露的平面类型和边缘和角落的延伸数量，从而将传统CeO2粉末中的八面体粒子的反应活性与纳米形状材料中的立方体粒子的反应活性联系起来。结果表明，碳烟的氧化也是一个表面相关的反应，为此设计的催化剂应考虑表面结构形态及其随温度的演变。
In this study, a series of conventional polycrystalline ceria and single-crystalline ceria nanorods and nanocubes were prepared by hydrothermal methods, and their structural, redo; and morphological properties were investigated using XRD, SEM, HRTEM, BET, temperature-programmed reduction, and oxygen storage capacity measurements. According to HRTEM, they are characterized by exposure of different surfaces: {100} surface for nanocubes; {100}, {110}, and in part {111} for nanorods; and mainly {1 1 1} for conventional polycrystalline ceria, with a morphology dominated by {111}-enclosed octahedral particles. The presence of more-reactive exposed surfaces affects the reaction of soot oxidation positively, with an increase in activity in nanoshaped materials compared with conventional ceria. Thermal aging, although detrimental for surface area, is shown to affect morphology by promoting irregular truncation of edges and corners and development of more reactive surface combinations in all crystal shapes. It is likely that thermal treatment, starting from either cubes or octahedral particles, induces the formation of a similar particle geometry whose activity is dependent on the type of plane exposed and by the number an extension of edge and corners, thus linking reactivity of octahedral particles in conventional ceria powders with that of cubes in nanoshaped materials. The results indicate that soot oxidation is also a surface-dependent reaction, and catalyst design for this purpose should allow for surface structure morphology and its evolution against temperature.