Ceria (CeO2)-based materials are widely used in industries such as catalysis, fuel cells, gas sensors, and particularly lie at the heart of the three-way catalysts (TWCs) as the Ce ions can easily switch between Ce4+ and Ce3+ driven by oxygen chemical potential. Compared with their counterparts, one-dimensional (1D) ceria nanomaterials are more reactive. Because they are usually synthesized under unusual conditions, and some reactive crystal planes may be obtained.
Activity of ceria nanomaterials at high temperature is closely associated with the changes of morphology, structure and chemical states at the microscopic scale. Significant sintering of ceria nanoparticles at high temperature or the transition from cubic structure to hexagonal structure will degrade the chemical activity of ceria nanoparticles. Moreover, defects of cerium oxide at high temperature are of great significance for the applications.
Very recently, Professor Xuedong Bai's group in Institute of Physics, Chinese Academy of Science studied the defect dynamics in ceria nanowires under heating by in situ aberration-corrected TEM. The defects appear and grow up while elevating temperature, and then grow into regular rhombic or hexagon shapes at 1023K. Much needed atomic-level structural detail at the defect interface is also provided. Although the defects are generated due to high temperature (up to 1023K), the structure of cubic fluorite remains unchanged and more reactive sites are introduced. This work provides a useful insight into designing ceria-based catalyst and ionic conductors.
The research was supported by the Program from Chinese Academy of Sciences (ZDYZ2015-1, XDB30000000, XDB07030100, and Y8K5261B11), National Natural Science Foundation (21773303, 21872172, 51472267, 51672007, 221322304, 11290161, 51572233, 61574121, and 51421002), National Key R&D Program (2016YFA0300804, 2016YFA0300903), and the National Program for Thousand Young Talents of China.
See the article: Li X, Wang W, Liu K, Bai X. Atomic-scale imaging of the defect dynamics in ceria nanowires under heating by in situ aberration-corrected TEM. Sci. China Chem., 2019, DOI: 10.1007/s11426-019-9624-x.