Study On Photocatalytic Activity Of CeO2 And Its Composites

The environmental pollution and energy shortages are^becoming serious problems with the rapid development of societies in 21st century, and green or sustainable chemistry has attracted the researchers’attention, throughout the world as a solution to these problems. In 1972, Fujishima and Honda discovered the phenomenon of photocatalytic splitting of water on a TiO2 electrode under ultraviolet (UV) light. Since then, enormous efforts have been devoted to the research of photocatalysts. As the most abundant contents of elements in rare earth resource, cerium dioxide has been used in many areas.Uniform-sized and monodiperse cerium dioxide porous hollow spheres (CeO2-PH) based on the Ostwaldripening process were fabricated by a simple solvothermal method in the absence of any templates. Thestructure and morphology of CeO2-PH and CeO2-NP (cerium dioxide nanoparticles) were characterizedby X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electronmicroscopy (FESEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The average diameter offace-centered cubic (fcc) phase CeO2-PH was ca.160 nm with a high specific surface area, and it iscomposed of small crystal grain particles (ca.10 nm). Furthermore, CeO2-PH has high activity for theevaluation of acetaldehyde decomposition. Optical, defect, and chemical state properties were characterized by Raman spectra, ultraviolet-visible absorption spectroscopy (UV-vis), and X-rayphotoelectron 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 activitysites on CeO2-PH in the photocatalytic process. The formation scheme and photocatalyic mechanismwill be discussed in this paper.In order to enhance the photocatalytic activity further, g-C3N4 was mixed with CeO2 by the planetary hybrid method. The activity has been enhanced a lot, which was attributed to the visible light response of g-C3N4. Graphitic carbon nitride (g-C3N4 with a lot of advantages such as hydrothermal and chemical stability, visible light response, non-poisonous, cheap raw material and so on, which has attracted many attention. The plausible mechanisms of the high activity would be investigated in the future research.