The influence of chelating agents on cerium oxide decorated on graphite synthesized by the hydrothermal route

Abstract Morphology features of cerium oxide nanoparticles, such as size and agglomeration, are important as a coating that improves corrosion resistance and as reinforcement in mechanical applications. In this work, the influence of two heat treatments (160° and 190 °C) in combination with three different chelating agents in the preparation of CeO2 and CeO2 decorated on graphite (CeO2_Gr) nanoparticles is studied. The novelty of this work is that CeO2_Gr was successfully prepared using the hydrothermal method. All the samples evaluated by X-ray diffraction exhibit a single fluorite-type structure in the cubic phase and Fm3m space group. The spherical harmonics method using the Fullprof Suite program was used to determine the average crystallite sizes, which were 9 nm for CeO2 and 7 nm for CeO2_Gr. Transmission electron micrographs for the prepared samples with citric acid showed non-agglomerate particles with homogeneous particle sizes and a quasi-spherical shape distribution. Raman spectra show a band centre at 600 cm-1 associated with the presence of Frenkel-type oxygen vacancies that induced the reduction of Ce4+ to Ce3+. The analysis of X-ray photoelectron spectra corroborates the coexistence of Ce3+ and Ce4+ species for CeO2 and CeO2_Gr nanoparticles. This work forms new perspectives in the development of CeO2 decorated on graphite prepared by the hydrothermal method to obtain composites not only for sensing applications and wastewater treatment but also for corrosion resistance and reinforcement materials.