Template-free Synthesis of Single-Crystalline-like CeO2 Hollow Nanocubes

Novel single-crystalline-like CeO 2 hollow nanocubes were synthesized through a solvothermal method using peroxyacetic acid (PAA) as the oxidant in the absence of any templates. The structure and morphology of CeO 2 hollow nanocubes were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The hollow nanocubes have an average edge length of 120 nm and shell thickness of 30 nm. TEM analyses demonstrate the formation of CeO 2 hollow nanocubes is ascribed to the combination of oriented attachment and Ostwald ripening. At the beginning, a well-defined cube-like geometrical structure is formed through oriented attachment of small nanocrystallites. Then, solid evacuation in the central part via Ostwald ripening leads to single-crystalline-like hollow nanocubes. It was found that both peroxide (CH 3 COOOH or H 2 O 2 ) and solution acidity are critical factors in determining the final morphology of the products. Compared to bulky CeO 2 powders, the prepared CeO 2 hollow nanocubes exhibited a higher catalytic activity toward CO oxidation.