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

Novel single-crystalline-like CeO2 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 CeO2 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 CeO2 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 (CH3COOOH or H2O2) and solution acidity are critical factors in determining the final morphology of the products. Compared to bulky CeO2 powders, the prepared CeO2 hollow nanocubes exhibited a higher catalytic activity toward CO oxidation.