Ceria rhombic microplates: Synthesis, characterization and catalytic activity

Herein, we report the synthesis, characterization, and catalytic activity of ceria rhombic micro plates obtained from aqueous cerium nitrate in presence of urea and CTAB. The material was characterized using SEM, TEM, XRD (low and wide angle), FTIR spectra, N2 adsorption, UV–DRS, and XPS analysis. The ceria consisted of plates of edge length ∼1 μm, and thickness ∼100 nm. BET surface area, and pore volume of the microplates were 57 m2/g, and 0.03 cm3/g, respectively. The particle size of the material was calculated from TEM analysis, XRD study, and BET surface area analysis. Cubic cerianite crystallites (CeO2) were detected by powder XRD, while the presence of Ce3+ was also evident from XPS and DR UV spectroscopy study. Tetravalent cerium constituted 56% of the total composition, as revealed by XPS analysis. Both Ce2O3 as well as oxygen vacancy contributed towards the presence of Ce3+ in the sample. The direct optical band gap of ceria is blue-shifted with respect to the bulk material indicating quantum-size confinement in nano crystallites in the plate structure. Bilayer assembly of CTAB has been proposed during the formation of ceria microplates. The system exhibited extremely high CO oxidation activity than the corresponding bulk oxide.

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► Rhombic ceria microplates synthesized at low temperature.
► Lamellar micelle structure of surfactant proposed.
► High activity for CO oxidation than bulk ceria.