Benign synthesis of ceria hollow nanocrystals by a template-free method

Ceria hollow nanocrystals with single-crystalline-like structure were prepared facilely by solvothermal synthesis free from templates, in which CeCl3 was proposed to hydrolyze with the assistance of poly(vinylpyrrolidone) (PVP) in the water–ethanol mixed solvent. TEM and SEM analyses demonstrated the formation of CeO2 hollow nanocrystals ascribed to a dissolution–recrystallization mechanism. It was found that both the counter ions of the cerium sources (e.g.CeCl3, Ce(NO3)3 or (NH4)2Ce(NO3)6) and the composition of the solvent mixture were critical factors in determining the final morphology of CeO2. The as-prepared CeO2 hollow nanocrystals with high crystallinity exhibited a higher catalytic activity and thermal stability towards CO oxidation.