晶态骨架介孔CeO2和CeO2-ZrO2的合成与结构表征

Synthesis and Characterization of Mesostructured Crystalline-Framework CeO_2 and CeO_2-ZrO_2 Composite

以乙酸铈、乙酸锫为无机源,嵌段共聚物P123为模版剂,采用溶胶-凝胶法合成了介孔CeO_2及CeO_2-ZrO_2复合体,用XRD、氮气吸附脱附、TEM、HRTEM、SAED等对材料进行了表征.结果表明,所得介孔CeO_2具有规则的晶态孔道结构,孔径约在10nm左右,特别是其孔壁晶粒高度定向排列且平行于孔道方向.原位高温TEM观测表明,该介孔CeO_2在800℃仍具有很高的孔道完整性.掺杂ZrO_2后发现,在ZrO_2摩尔含量低于30%时仍具备高度定向排列结构,高于30%时骨架晶粒取向逐渐趋向无序化.

Mesostuctured CeO2 and CeO2-ZrO2 composite were synthesized via sol-gel method using cerium acetate and zirconium acetate as inorganic species, block copolymer P123 as surfactant, respectively. The obtained samples were characterized by XRD, N2 adsorption-desorption, TEM, HRTEM, and SAED. Results show that the mesostrutured CeO2 possesses crystalline framework with the average pore size of ca. 10nm. In particular, it＇s revealed that the inorganic framework consists of highly oriented nanocrystals with the preferential orientation parallel to the channel arrays. In situ TEM observation equipped with the heating holder demonstrates that the mesostructured CeO2 maintains perfect pore integrity up to 800℃ due to the confined growth tendency of oriented grains. Mesostructured CeO2-ZrO2 composite remains the similar framework structure when ZrO2 molar ratio is less than 30%, however, it appears to transform to random oriented polycrystalline mesostructure when ZrO2 molar ratio is higher than 30%.