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Shape-Controlled Synthesis of CeO2 Nanoparticles: Effects of Different Precursors on the Formation of Oxygen Vacancies ; Stability and Activity in the Catalyzed Oxidation Reaction

Oxygen storage in solid catalyst is very important for industrial oxidation reactions such as HCl oxidation reaction (Deacon process). Ceria nanoparticles act as promising catalysts for HCl oxidation reaction. Ceria posseses high OSC (oxgen storage capacity) which is a measure of the oxygen quantity that material can store and release. This makes ceria suitable for redox reactions which usually follow Mars-van Krevelen mechanism (surface oxygen atoms directly involved in reactions) [1]. Because of the reversible change in oxidation state from Ce4+ to Ce3+, the neutral oxygen vacancies are formed. Giving the fact that redox reactions take place at ceria surface, it’s important to investigate the type of the surface in different nanostructured ceria-based materials. As a result, different shapes show different facets of preferential orientation ((111) for octahedrons, (110) for nanorods and (100) for nanocubes) thus also showing different stability and activity [2]. An important factor that might have an impact on properties of synthesized ceria is a type of a precursor. Type of an anion in a precursor salt might have an impact on crystallization of ceria thus also on formation of oxygen vacancies. In this research, shape-controlled CeO2 nanoparticles (nanorods and nanocubes) were synthesized by previously published hydrothermal method [3] and by two different cerium precursors (Ce(NO3)3 6H2O and CeCl3 7H2O). Synthesized materials have been characterized by powder X- ray diffraction (PXRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM). Obtained results show pronounced effect of different cerium precursors on the crystallization of ceria and formation of oxygen vacancies.

CeO2 ; nanorods ; nanocubes ; oxygen vacancy, PXRD ; Raman

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