Preparation and characterization of highly dispersed silica-supported ceria Original Research Article

Silica-supported ceria samples of various cerium content ( 0.008 to 11 % Ce ) were prepared either through anchoring cerium acetylacetonate in organic medium or by capillary aqueous impregnation of cerium nitrate. After calcination, ceria particles as small as 2 nm were obtained by the anchoring process while impregnation leads to larger particles (5–9 nm). These samples show significant spectroscopic differences with pure ceria: (i) increase of the X-ray photoelectron spectroscopy binding energies of the Ce 3d and of the O 1s lines, (ii) blue shift of the band gap measured by diffuse reflectance, (iii) observation of narrow UV bands at low cerium content, (iv) increase of the CO stretching vibration of CO-Ce4+ terminal species. These results are ascribed to the coordinative unsaturation of surface cerium and oxygen ions.