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

In this work, we bring the first large-scale study of grain growth kinetics of copper-doped ceria nanoparticles. Since most of the notable applications of ceria nanoparticles, such as catalysis or solid oxide fuel cells, require its use at elevated temperatures, particle agglomeration and aggregation occur, which diminish the favorable properties of ceria. Doping with copper was chosen as a strategy for the increase of ceria thermal stability. Pure ceria and ceria doped with 10, 20, 30 and 40 mol.% of copper were prepared by hydrothermal synthesis, thermally treated at temperatures in the range between 300 and 700 degrees C at various annealing times and analyzed using X-ray diffraction analysis and transmission electron microscopy. An isothermal grain growth kinetics analysis was conducted based on the crystallite sizes calculated through the Scherrer equation in order to determine the influence of copper doping on ceria thermal stability. Three temperature ranges with different grain growth regimes and kinetic parameters were defined. The activation energies increase, while the grain growth exponents decrease from low to high temperature range, which is in concordance with the change in the growth mechanism from diffusion to Ostwald-Ripening. It was established that the thermal stability of ceria does not solely depend on the lattice defects introduced by copper, but also on microstructure, porosity and sample preparation. Still, the addition of copper has a positive influence on thermal stability of ceria up to 650 degrees C, and the sample with 40 mol.% of added copper has the slowest grain growth in the full studied temperature range.

Automated summary

In this study, the grain growth kinetics of copper-doped ceria nanoparticles were investigated. It was found that doping with copper improves the thermal stability of ceria, and the sample with 40 mol.% of added copper has the slowest grain growth below 650 degrees C.