engleski

Thermal stability study of hydrothermally-derived copper-doped cerium (IV) oxide nanoparticles

Cerium (IV) oxide (CeO2) is known for its high oxygen storage capacity, low cost, good mechanical properties and poisoning resistance. On that account, ceria-based nanocatalysts are widely applied in various fields such as industry, environmental protection and energy generation. Most of the chemical processes in question require elevated temperatures, where the problem of grain growth of nanoparticles occurs. The increase in the particle size causes the reduction of specific surface area and, consequently, the decrease of catalytic activity. Doping of ceria with different transition metals is one way of slowing down the growth process. [1, 2] Our previous research showed that the addition of 10 mol. % of copper increases the thermal stability [2], as well as the catalytic activity [3] of CeO2, which is why Cu was chosen as a dopant for further research. In this work, pure and copper doped cerium (IV) oxide nanoparticles (CuxCe1-xO2, where x = 0, 0.1, 0.2, 0.3 and 0.4) were prepared by hydrothermal synthesis and characterized using X- ray powder diffraction (XRD) and transmission electron microscopy (TEM). The crystallite sizes determined from XRD patterns by using the Scherrer’s equation were between 3.7 and 3.1 nm, while TEM analysis showed spherical particles with sizes matching the calculated crystallite sizes. As-prepared samples were thermally treated at different temperatures and processing times, after which an isothermal model was applied in the study of grain growth kinetics. It was established that the grain growth process can be divided into two regions, low-temperature (300- 450 °C) and high-temperature (500-700°C) region, each with its own growth regime. While the grain growth is sluggish at lower temperatures, it accelerates at higher temperatures in all of the samples. However, the results show that the addition of copper has a positive effect on the thermal stability of cerium (IV) oxide, and the grain growth decreases with the increasing copper amount.

thermal stability ; ceria ; copper ; nanoparticles ; grain growth

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