Porous cerium dioxide hollow spheres and their photocatalytic performance

Uniform-sized and monodiperse cerium dioxide porous hollow spheres (CeO2-PH) based on the Ostwald ripening process were fabricated by a simple solvothermal method in the absence of any templates. The structure and morphology of CeO2-PH and CeO2-NP (cerium dioxide nanoparticles) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The average diameter of face-centered cubic (fcc) phase CeO2-PH was ca. 160 nm with a high specific surface area, and it is composed of small crystal grain particles (ca. 10 nm). Furthermore, CeO2-PH has high activity for the evaluation of acetaldehyde decomposition. Optical, defect, and chemical state properties were characterized by Raman spectra, ultraviolet-visible absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The presence of Ce3+ ions narrowed the band gap of CeO2-PH, resulting in the high light harvesting. The large amount of oxygen vacancy defects provided many activity sites on CeO2-PH in the photocatalytic process. The formation scheme and photocatalyic mechanism will be discussed in this paper.