Oxygen Vacancies Of Ceria And Its Effects On Photocatalytic Dye Degradation

Dye wastewater from textile,food and coloring industries has seriously damaged aquatic ecosystems and human health.To date,a wide range of dye removal techniques have been developed,among which photocatalytic degradation has been identified as the most promising one.In recent years,CeO2 semiconductor has become a research hotspot due to its unique redox properties.Researches showed that oxygen vacancy of oxygen-containing semiconductor played crucial role in photocatalytic reaction,but the main factors in affecting the degradation activity of CeO2 is yet to be determined.For this reason,CeO2 with different morphology,specific surface area,and oxygen vacancy content was prepared by different hydrothermal temperatures and high-temperature calcination.The structure,morphology,specific surface area,and optical properties of the prepared catalysts were characterized by means of X-ray powder diffraction(XRD),scanning/transmission electron microscopy(SEM/TEM),nitrogen adsorption and desorption,ultraviolet-visible diffuse reflection(UV-vis)and fluorescence spectrum(PL).The oxygen vacancy of CeO2 was analyzed qualitatively and semi-quantitatively by Raman and X-ray photoelectron spectroscopy(XPS).Photocatalytic degradation of rhodamine B(RhB)aqueous solution was selected as a probe reaction.The experimental results indicate that the oxygen vacancy on the surface of CeO2 is a leading factor in affecting the photocatalytic degradation activity.In addition,in order to address the issue of weak visible absorption of CeO2,Au with visible light absorption by surface plasmon resonance(SPR)was used to prepare Au/CeO2.It was found that excessive loading of gold would decrease the surface oxygen vacancies of the CeO2 and reduce its activity.The active sites of Au/CeO2 were systemically explored by changing the method of Au loading.The results confirm that the surface oxygen vacancy content is still a leading factor in affecting photocatalytic dye degradation of Au/CeO2.The fundamental knowledge and insight generated in this study will provide an important scientific basis for the potential application of CeO2-based catalysts for photocatalytic dye degradation.