engleski

The effect of nanomaterial shape on formation of oxygen vacancies: non-doped and doped ceria

Oxygen storage in solid catalyst is very important for heteregeneous oxidation reactions of environmentally harmful gases such as CO, CHx and HCl. Ceria nanoparticles act as promising catalysts these kind of reactions because it possesses high OSC (oxgen storage capacity). When reducing size of a material, surface becomes more important than a bulk. Also, surface defects are induced which favor high OSC. This is why in these kinds of reactions the interaction of a gas phase with solid surface is studied in detail. Redox reactions which occur on ceria surface usually follow Mars-van Krevelen mechanism (surface oxygen atoms directly involved in reactions). Neutral oxygen vacancies are formed because of the reversible change in oxidation state from Ce4+ to Ce3+. These vacancies are formed in different quantities depending on a shape of synthesized nanomaterial. Different shapes show different facets of preferential orientation ((110) for nanorods and (100) for nanocubes) thus also showing different stability and activity. In this research, shape-controlled CeO2 nanoparticles (nanorods and nanocubes) and Zr-doped ceria nanorods were synthesized by hydrothermal method. Synthesized materials have been characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The value of surface area has been measured by BET method. Obtained results show pronounced effect of different nanoshape of ceria on formation of oxygen vacancies. The authors acknowledge Croatian Science Foundation-Unity through knowledge fund project PZS-2019-02-2467 for full financial support.

ceria ; ceria-zirconia ; Mars-van Krevelen mechanism ; catalysis

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