Abstract
Nano-crystalline CeO2 was synthesized via the urea-hydrothermal method without templates or structure-directing agents. The synthesis parameters Ce3+ to Ce4+ and urea to cation molar ratios, reaction temperature and reaction time were varied to analyze their effect on morphology, texture and reducibility. The analysis of the obtained morphologies provides strong evidence of a hierarchical and sequential template-free self-assembly process that evolves from shuttles to dumbbells to spheres. In all cases, the morphology of samples remains unchanged even after calcination at 500 °C. The presence of Ce4+ in the initial solution clearly provides the full self-assembly sequence and is decisive for obtaining non-hollow spheres of CeO2 with high specific surface area and high pore volume. Besides, if only Ce3+ is present, typical CeOHCO3 shuttle-like particles with orthorhombic structure are obtained. The use of Ce3+ in combination with Ce4+ produces partial sequences of the self-assembly process that provide a strong indication of the hierarchical sequence.The urea to cation molar ratio controls the nucleation process and proves to be crucial to obtain the self-assembly sequence. On the other hand, temperature and reaction time show a moderate effect on morphology.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
