Layer-by-layer synthesis of hollow spherical CeO2 templated by carbon spheres

Abstract

CeO 2 hollow spheres were successfully prepared via a layer-by-layer (LBL) method using carbon spheres as sacrificial template and hexamethylenetetramine as precipitating agent. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrum (XPS) were used for their characterization. The obtained products exhibit hollow spherical structure with a diameter of ca. 250 nm as well as the thin shell about ca. 20 nm composed of various oriented polycrystals, and the Brunauer–Emmett–Teller (BET) surface area was measured to be 126 m 2 g −1 . Calcination temperature is found to be crucial to the integrity of the hollow spheres and has to be below 973 K to achieve well defined hollow spheres. CO conversion was used as a catalytic test reaction revealing that the activity of the hollow spherical products was substantially higher than that of the non-hollow counterpart.